SURGICAL ANATOMY OF THE HEAD AND NECK D E A V E R BY THE SAME AUTHOR SURGICAL ANATOMY.— A Treatise on Human Anatomy in its Application to the Practice of Medicine and Sargery. In Three Royal Octavo Volumes, including 499 Full-page Plates. Sold by Subscription Only. Full Sheep or Half Morocco, $30.00 ; Half Russia, $33.00 net. GENERAL ARRANGEMENT OP CONTENTS Volume I. — Upper Extremitj' — Back of Neck — Shoukler — Tniiik — Cranium — Soalp — Face. Volume II. — Xeck — ]\Iouth — Plianiix — Larynx — Nose— Orliit — Eyel)aU — Organ of Hearing — Brain — JIale Perineum — Female Perineum. Volume III. — Abdominal Wall — Abdominal Cavitj' — Pelvic Cavity — Che-str — Lower Extremity. APPENDICITIS. — Its History, Anatomy, Etiology, Pathology, Symptoms, Diagnosis, Prognosis, Treatment, Complications and Sequelse, with five Colored and many other Full-page Plates. Third Edition. Cloth, $5.00. ENLARGEMENT OF THE PROSTATE.— Its History, Anatomy, Pathology, Causes, Symptoms Diagnosis, Treatment, and Technique of Operations. Illustrated. Oc- tavo. In Press. SURGICAL ANATOMY OF THE HEAD AND NECK JOHX B. DEAVER, M.D SURGEOS-IS-CIIIEF TO THE GKUMAN IMSIMTAI., PHILADELPHIA jLH.STRATED by 177 PLATES NEARLY ALL DRAWN FllOM ORIGINAL DISSECTIONS NECK; MOUTH; PHARYNX; LARYNX; NOSE; ORBIT; EYEBALL; ORGAN OF HEARING; BRAIN; BACK OF NECK; CRANIUM; SCALP; FACE. PHILADELPHIA P. BLAKISTON'S SON & CO. 1 1 J WALNUT STREET 1 904 Copyright, 1904, by P. Blakiston's Son k Co. WM. F. FELL CO. ELECTROTyPenS AND PRINTERS 1320-34 SAN^OM STREET PHILADELPHIA 700 PUBLISHERS' NOTE. This volume has been made up from those sections of Dr. Deaver's complete work on "Surgical Anatomy" which treat specially of the regions which arc of greatest interest to tiiose practitioners who confine their work to Diseases of tlie Eye, Ear, Nose, Mouth, Throat, and Nervous System, and [irovides this class of specialists with an absolutely unique book, useful, practical, new. The illustrations which were prepared to exemplify the text have l)een drawn directly from dissections made for the purpose. They are accurate, artistic, real- istic, and are reproduced in accordance with the liighest standards of tyiiography. The text is clear, succinct and systematically arranged. It sets forth the prin- ciples of anatomy as applied to medicine and surgery and describes with thorough- ness the anatomic conditions fundamental to the various surgical operations. G350;:.l CONTENTS PACK THE NECK 17 SuRFACE Anatomy of the Neck, 17 Dissection of the Neck, 2G Triangles of Neck, 54 Cervical Plexus of Nei-ves, G5 Extrinsic JIuseles of Toiijiue, 108 Tiiyroid Gland, 1212 Axillary or Brachial Plcxn.s, 148 Bursse of Neck, 156 Lyiiiiihalic Glands of Neck, 159 LiG.ATiON OF Arteries of Head and Neck, IGO Operations Upon Nerves of Head a.vd Neck, 196 THE MOUTH . 209 The Tongue : 216 Muscles of the Tongue, 219 The Tonsils 224 THE PHARYNX, 227 Kel.\tio\s of the Pharynx, 237 Veins of the Pharynx 238 Lymphatic Vessels of the Pharynx, 238 THE SOFT PALATE, 238 THE LARYNX, 247 Veins of the Larynx 205 Lymph.\tic A'e.ssels of the Larynx 265 The Vocal Cords, 266 The Cartilages of the Larynx, 270 THE NOSE 284 The Nasal Bones 286 Cartilages of the Nose 286 THE FRONTAL SLXUSES, 308 THE ANTRUM OF HIGHMORE, 312 THE ETHMOID SINUSES, 315 THE SPHENOID SINUSES, 315 THE ORBIT 316 Dissection of the Orbit, 317 MrscLES OF THE Orbit, 328 THE LACRYMAL APPARATUS 351 vii viii CONTENTS. PAGE THE EYEBALL, . - 357 THE ORGAN OF HEAEING, 399 The External Ear, 399 The Middle Ear, 407 The Internal Ear, 431 MEMBRANES AND VESSELS OF THE BRAIN 438 THE ARTERIES OF THE BRAIN. 445 THE VEINS OF THE BRAIN, 4.')4 THE BRAIN, 455 Surface Markings op the Brain, 455 The Origins of the Cranial Nerves, 4til The Cerebrum, 4(17 Surfiice Jlai-kings, 467 Cranio-Cerebral Topograpliy, 499 Motor Centers, 500 Interior of Cerebrum, 512 The Lateral Veiitrieles, 518 THE PONS VAROLII, 549 THE MEDULLA OBLONGATA, 553 THE CEREBELLUM, 558 SECTIONS OF THE BRAIN, 507 JOINTS OF THE HEAD AND NECK, 573 DISLOCATIONS OF THE BONES OF THE VAULT AND BASE OP SKULL, .... 579 DISLOCATION OF THE LOWER JAW, 579 EXCISION OF THE UPPER JAW 579 EXCISION OF THE LOWER JAW 583 FRACTURES OF THE SKULL, 584 SURFACE ANATOMY OF THE CRANIUM, 587 SURFACE ANATOMY OF THE FACE, 592 SCALP 601 FACE, 625 PrEiiVGO-jiAxii.i.AKv Hkgion 676 TIIK MEMBRANES AND VESSELS OF THE BRAIN 704 Intra cranial Course and BIode of Exit op the Cranial Nerves 727 INDEX, . . 737 LIST OF ILLUSTRATIONS. PLATE PAGE I. Lines of Incision fur EsjMisure of Arteii(^t4 and Nerves of Neck, 20 II. Surface Anatomy of Neck, and Lines of Incision in Laryngotomy, High Tra- cheutoniy anil Low Traelieotoiuy, 21 III. lacisions for Dissection of Neck, auclLines for Vessels and Nerves of Neck, . 27 IV. Platysma Jlyoides Muscle, 30 V. Superficial Layer of Deep Fascia, Supei-ficial Veins, and Nerves of Neck, ... 34 VI. Veins of Scalp, Face, and Neck, 35 VII. Section of Neck at Sixth Cervical Vertebra, 39 VIII. Diagram of Deep Cervical Fascia, 41 IX. CeiTieal Plexus, 44 X. Superficial Structures of Neck, 50 XI. Superficial Structures of Neck 51 XII. Diagram of Triangles of Neck, 55 XIII. Incisions for Di.ssection and Lines for Arteries, Veins, and Nerves of Neck, . . 07 XIV. Vessels and Nerves of Neck 70 XV. Vessels and Nefves of Neck, 71 XVI. Deep Structures of Neck — Carotid Arteries and Piieuiuogastric Nerve, .... 78 XVII. Sympathetic Nerve and Laryngeal Nerves, 79 XVIII. Diagram of Subclavian and Carotid Arteries and Tbeir Branches, 87 XIX. Veins of Head and Neck 89 XX. Superficial Stiiictures of Neck, 100 XXI. Superficial Structures of Neck, 101 XXII. Arteries of Tongue and Tonsil, 105 XXIII. Extrin.sic Muscles of Tongue, 109 XXIV. Supei-ficial Structures Near Median Line of Neck, 117 XX^^ Thyroid Body 123 XXA'I. Thoracic Duet, 129 XX^'II. Collateral Circulation after Ligation of Subclavian Artery, 133 XX^'III. Vertebral Artery in Transverse Processes, 137 XXIX. Vessels of Neck 140 XXX. Vessels of Neck, 141 XXXI. Axillary or Brachial Plexus pf Nerves, 149 XXXII. Prevertebraniu.-icles ],52 XXXIII. Lymiihatic Glands and Lymi)hatic Vessels of Neck, 157 XXXIV. Lines of Inei.sion for Operations on Nerves and Arteries of Head and Neck, . . 161 XXXV. Expo.sure of ImKinjinate Artery, 104 XXX\'I. Expo.sure of Third Portion of Subclavian Artery, 107 XXX\'II. Diagram of Collateral Circulation after Ligation of Subclavian and Common Carotid Arteries, 171 XXXVIII. Expo.sure of Vertebral Arteiy and Inferior Thyroid at Origin — Left Side of Neck .'^ 174 XXXIX. Ligation of First and Seconil Portions of Lingual Artery; Superior Thyroid Artery; Inferior Thyroid Artery, 177 ix LIST OF ILLUSTRATIONS. PLATE XL. XLI. XLII. XLIII. XLIY. XLV. XLVI. XLVII. XLAIII. XLIX. L. LI. LII. LIIL LIV. LV. LVL LVIL LAIII. LIX. LX. LXL LXIT. LXIII. LXIV. LXV. LXVL LXV 1 1. LXVIIL LXIX. LXX. LXXI. LXXII. LXXIIL LXX TV. LXXV. lA'XVI. LXXVIL LXXVIIL LXXTX. LXXX. LXXXL lAXXH. LXXXin. LXXXIV. LXXXV. LXXX V I. Lxxxvn. LXXX VII [. LXXXLX. XC. P.IGE Exposure of Inferior Dental Nerve ; Facial Artery ; Spinal Accessory Nerve and Superficial Brauches of Cervical Plexus; anrl Cnuinion Carotiil Artery in Superior Carotid Triangle, 182 Exposure of External Carotid and Internal Carotid, and of the Superior Thyroiil, Lingual, Facial, and Occipital Arteries at Tlicir Oiigin, and Exposure i.f Common Carotid in the Inferior Carotid Triangle, ]S3 Exposure of Occipital Artery for Ligation, ]'.)2 Exposure of Auriculo-temporal Nerve and Temporal Artery, 193 Exposure of Supraorbital Artery and Nerve, 197 Exposure of Lingual Artery, 202 Exposure of Facial Nerve, 203 Exposure of Bracliial Plexus of Nerves, 208 Vertical Section of Mouth, Pharynx, Larynx, and Nose, 212 Superior Aperture of Larynx and Dorsum of Tongue, 218 Transverse Section of One-half of Tongue, 221 Constrictor Muscles of Pharynx, 229 Pharyngeal Tonsil and Bursa, 233 Interior of Pharynx, 23G Anterior View of Jloutli 239 Muscles of Soft Palate — Anterior Mew, 242 Muscles of Soft Palate, 243 Superior Aperture of Larynx, 250 Larynx and Crico-thyroid Sluscle 2.51 Anterior View of Larynx, Including the Cricothyroid Membranes, 254 Jlusoles of Larynx — Posterior View, 258 JMuscles of Larynx — Lateral ^'iew, 259 Nerves and Arteries of Larynx, 263 Lateral View of Interior of Larynx, 267 Cartilages of Larynx, 27 1 Surface IMarks of Neck and Lines of Incision f )r Laryngotomy and Tracheotomy, 278 Operation of Laryngotomy and High and Low Tracheotomy, 279 Lateral Cartilages of tlie Nose, 287 Cartilages at Base of Nose 290 Nasal Septum, 291 IMeatuses of Nose and Turbinated Bones— Lateral View, ... 296 Orifices of Accessory Air-chambers of Nose, 298 Olfactory Nerves, 303 Anterior View of Nasal Fosspb, 306 I'osterior View of Nasal Fossre, 309 Oridces of Nasal Duct and Accessory Air-chambers of Niise, 314 Orbital Fascia and Capsule of Tenon — Sagittal Section 320 Orbital Fascia and Capsule of Tenon — Transverse Section, 321 Nerves and Muscles of Orbit, 326 Muscles of Oibit, 330 Arteries and Veins of Orbit, 334 Nerves of Orbit 339 Section of Cavernous Sinus — Structures Traversing Spheuoi.l Fissure, .... 343 Tensor Tarsi and Corrugator Supei'cilii Muscles, 346 Lacrymal Ajuiaratus 350 Sagittal Section of Ui)i)er Eyelid, 353 [Meibomian (Jlands and Laerymal A])paratus, 355- Meridional Sei'tion of Eye, 360 Meridional Section of Ciliary Region of Eyeball, 365 External and Middle Coats of Eyeball 369 Ciliary Region of Eyeball (from Lion's Eye in Museum of Univ. of Pemia.), . 372 LIST OF ILLUSTRATIONS. xi PI.ATK P.4GK XCr. Ciliary Ntrves 370 X("ll. Ciliary Aiteiios, 377 XCIII. Rotiua of Posterior Oiio-lialf of Eight Eyeball, 381 XCn'. Blood-vessels of I'lyeball (after Leber) 384 XCV. Lens, Iris, ami Ciliary Hody at Rest; the Same Structures lluring Aecommo- dation. Kniniitroiiic Eye, 388 XCVL Myopic Eye ; i^lyopie Eye with Concave Lens ; Hyperoinc Eye ; Ilyperopic Eye with Convex Lens, 389 XC\'H. Annual Posterior Synechia, 304 XCVIIL Pinna of Ear, . ." 398 XCIX. Litrinsic Muscles of Piinia 401 C. External and Midille Ear 405 CL Anterior Vii'W of Right Tympanum, 409 CIL Membrana Tympani and Its Inclination, 413 cm. External View of ^Membrana Tympani ol' Lel't Ear, . . . / 418 CIV. Internal View of Right Tynjpanum, 422 CV. External View of Bony Labyrinth and Semicircular Canals, 427 CVI. Interior of Osseous Labyrinth of Left Internal Ivir, 430 CWl. Interior of Osseous Portion of Cochlea, 434 CVIII. Section of Osseous Portimi of Cochlea, 435 CIX. Diagram of Membranuus Labyrinth, 439 ex. Circle of Willis and Arteries of Brain 444 CXI. Middle Ccreljral Artery 447 CXJI. Arteries at Base of Brain, 452 CXIII. Base of Brain and Superfici.d Oiigin of Cranial Nerves, 458 CXIV. Diagram of Optic Tr.icts, 463 CXV. Island of Rcil, 471 CXA'I. Diagram of Lateral Surface of Cerebrum, 474 CXVII. External Surface of Cerelirum, 477 CXVIII. Superior Surface of Cerebrum, . 480 CXIX. Inferior Surface of Frontal Lobe, 483 CXX. Median and Ini'erior Surfaces of Cerebrum 488 CXXI. Inferior Surface of Occi])ital and Temporal Lobes, 494 CXXII. Median and Inferior Surfaces of Cerebrum, 497 CXXIII. Motor and Sensory Areas of Cerebrum (after Ferrier), 501 CXXI\^. Lines for Fissures, Lower Level of Cerebrum 506 CXXA'. Corpus Callosum and ILjrizontal Section of Cerebrum, 513 CXX^'I. Internal Surface of Cerebrum and Section of Ventricles of Brain, 516 CXXA'II. Bodies, Anterior Cornua, and Posterior Cornua of Lateral Ventricles, .... 519 CXX\'III. Fornix and Lateral ^^■ntricles. and Descending Cornu of Left Lateral Ventricle, 523 CXXrX. Diagram of the Ventiiclcs — Sujierior View, 528 CXXX. Diagram of the ^\■ntricles— Lateral View, 529 CXXXI. Velum Interpositum and Choroid Plexus, 533 CXXXII. Ventricles and Nuclei of Brain, 536 CXXXIII. Lateral View of Corpora Quadrigemina, P(]ns, and Medulla, 539 CXXXIV. Third and Fourth Ventricles and CorjxiiM Qnadi'igcmina 542 CXX XV. Transverse Section of Cerebrum, 546 CXX.WI. Pons, Medulla, and Superficial Origins of Cranial Nerves 5.52 CXXX \' II. Third and Fourth ^'eutricles and Corpora Quadrigemina, 556 CXXX\"III. Inferior and Superior Surfaces of Cerebellum 560 CXXX IX. Coronal Section of Cerebrum, 564 CXL. Coronal Section of Ccrebrnni, Anterior to Optic Chia.sm 565 CXLI. Coronal Section of Cerebrum Through Corpora Albicantia and Middle Commissure, 569 CXLII. Parietal .and Transverse Occipital Fi.ssures. Lines in which the Bone is Divided iu Excision of the Ui)per Jaw, 572 xii LIST OF ILLUSTRATIONS. PLATE PAGE CXLIII. Teruporo-masillaiy Articulation — External View, 576 UXLIV. Temporo-maxillary Articulation — Internal "^'iew, 577 CXLV. Fractures of Lower Jaw, 581 CXLVI. Cranial Landmarks and Lines of Cerebral Fissures, 589 CXLVII. Incisions for Dissection, 597 CXLVIII. Layers of Scalp, 599 Cirsoid Aneur.vsm, 599 CXLIX. Superficial Fascia of Scalp 603 CL. Arteries of Scalp and Face, 608 CLI. Nerves of Scalp and Facial Nerve, 609 CLII. Arteries, NeiTes, and Muscles of Scalp and Face, . 613 CLIII. Temporal Fascia and Nerves of Face, 620 CLIV. Temiioral JIuscle, 621 CLV. Incisions for Dissection and Lines for Vessels and Nerves of Face, 623 CL'\'I. Bluscles of Face and Scalp, 627 CLVII. Tensor Tarsi and Corrugator Supereilii Muscles, 632 CLVIII. Arteries of Scalp and Face, 640 CLIX. Arteries, Nerves, and ^Muscles of Scalp and Face, 641 CLX. Veins of Scalp, Face, and Neck 645 CLXI. Palpebral Fissure and Eyeball— Eyelids Everted, 649 CLXII. Lacrymal Apparatus and Meibomian Glands, 653 CLXIIL Pinna, 661 CLXIV. Intrinsic Muscles of Pinna 663 CLXV. Nerves of Scalp and Facial Nerve 667 CLXA'I. Operation for Exjiosure of Facial Nerve, 672 CLX^'II. Temporal Fascia and Nerves of Face 673 CLXA'III. Pterygoid J^Inscles and Internal Maxillary Artery 678 CLXIX. Internal ^Maxillary Artery and Brandies, 682 CLXX. Inferior Maxillary Nerve; 686 CLXXI. Olfactory Nerves and Internal View of the Spliono-palatine and Otic Ganglia, . . 690 CLXXII. Superior and Inferiiir 3Iaxillary Nerves, 695 CLXXIII. Diiiloic Veins 705 CLXXIV. Dura Jlater, Arachnoid, and Meningeal Vessels, 709 CLXXV. Sinuses and Processes of Dura Mater, 714 CLXXVL Sinuses and Cranial Nerves 715 CLXXVII. Lines for Sinuses, 721 SURGICAL ANATOMY OK TIIK HEAD AND NECK. Dlii;^ECTluy OF THE NECK. SURFACE ANATOMY. The surface anatomy of the region of the neck should be considered in re- gard to its superficial veins and nerves, the upper portion of the respiratory tract, the prominent muscles, the ])uInionary apices, the sterno-cluvicular joints, and the hirge vessels. The skin of the front of the neck may lie eitlier in hui-jzontal or vertical folds, the former being more common, and always seen in infants. In stout persons the deposition of fat in the subcutaneous tissues makes these folds very prominent, producing the cimdition known as " double chin." Vertical folds occur in the aged, especially in those who have lost much adipose tissue, in consequence of which the old and inela.stic skin can no longer adapt itself The anterior and most prominent ridges of the surface of the neck an' lUie to the anterior liorder of the platysma myoides muscles. Length of the neck. — The variabilit}- which exists in the length of the necks of dilferent persons is due, as Merkel points out, to three factors : First, to the position of the shoulder girdle ; second, to the contour of the border of the trape- zius muscle ; third, to the thickness of the neck. The superior thoracic aperture is oblicjue from behind forward and downward ; in some persons this nbli(juity is greater than in others, so that the supra-sternal notch may be on a level with the third thoracic vertebra ; this will consequently cause the inner end of the clavicle to lie lower, and the neck will appear longer. When the border of the trajwzius muscle slopes graduaUy toward the shoulder instead of curving I'ather abruptly out u aid, the neck will appear longer ; a thin neck presents a longer appearance tlian a thick and muscular one. The length of the cervical jiortion of the spinal column does not vary much in different persons. The sterno-cleido-mastoid muscle, because of its prominence throughout its course, is the great landmark of the neck, and extends from the sterno- S-2 17 18 SURGICAL ANATOMY. clavicular junction to behind the eai'. An_v movement of the head which draws the ear downward and forward renders the muscle prominent. It divides the side of the neck into the anterior and the posterior triangle. In subcutaneous section of the lower attachments of this muscle it must not be forgotten that the fossa supraclavicularis minor, the triangular interval between the sternal and clavicular origins, marks the position of the common carotid artery and internal jugular vein. The supra-sternal fossa, termed "fonticulus gtdturis" by the old writers, lies betM'een the sternal origins of the two sterno-mastoid muscles. In Iwautiful necks it is, of course, filled with fat, but even then the rounded contour of the sternal attachment of this muscle is evident, though graceful withal. "When the finger is deeply insinuated into the supra-sternal notch, the pulsations of the innominate artery can often be felt ; those of a dilated aortic arch may also be perceived. Retraction of the tissues in the supra-sternal notch during inspiration is often seen in marked dyspnea, as in larj'ngeal obstruction. The sterno-clavicular joint may be readily identified at the side of the supra- sternal notch — in stout persons by movement, and bj' sight alone in thin individ- uals. Its upper border marks the origin of the innominate vein upon both sides, behind which, on the left side, lies the common carotid artery, and on the right side, the bifurcation of the innominate artery ; still farther back is the apex of the lung. The innominate arterj' is relatively higher in children than in adults. The apex of the lung extends from one to two inches above the clavicle, and higher in very long necks ; it is also higher in women than in men. It is covered l)y part of the scalenus anticus, sterno-thyroid, and sterno-cleido-mastoid muscles, and to the inner side of the scalenus anticus muscle it is crossed transversely by the subclavian vessels. This portion of the lung is more commonly the site of tubercular deposits, ajid should be examined by percussion and auscultation immediately above and ])elow the inner part of the clavicle. The supra-clavicular fossa is the depression above the clavicle lietween the sterno-mastfiid and trapezius muscles. The external jugular vein terminates here. It is well defined in emaciation due to wasting diseases and in oM age. It marks the place where the vessels and nerves pass from the neck into the axilla, and a knife thrust backward, downward, and inward through this depression would injure a number of important structures. Tlie transverse processes of the cervical vertebnc may be felt by pres.sure directed inward tln-ough the uj)}icr part df the fossa. Ill Ihin jiersons Uie jiostcrior lielly of the omd-liyoid muscle can also be felt in this space, just above and i)arallel to the clavicle.. During inspiration the tension ]iroduced by the omo-liyoid muscle on the deej) cervical fascia is jdainly PLATE I, External carotid a. First portion of lingual a. Inferior dental n Facial n ainal accessory n anterior to sterno-mastoid m Spinal accessory n. posterior to sterno- mastoid m. and superficial branches of cervical plexus Facial a. Second portion of lingual a. Superior thyroid a. Common carotid a. in superior carotid triangle Common carotid a. in inferior carotid triangle X \ 3d portion of subclavian a nnommate a. LINES OF INCISION FOR EXPOSURE OF ARTERIES AND NERVES, 20 PLATE II. f^ Prominence produced by sterno- mastoid m. Common line of incision for laryngotomy.high traciieotomy and low tracheotomy Ridge over clavicle Supraclavicular fossa -Segment of line locating incision in laryngotomy -Segment of line locating incision in high tracheotomy Segment of line locating incision in low tracheotomy Suprasternal fossa Fossa supraclavicularis minor SURFACE ANATOMY OF NECK, AND LINES OF INJISION IN LARYNGOTOMY, HIGH TRACHEOTOMY, AND LOW TRACHEOTOMY. 21 SURFACE AXATOMY OF THE MCCK. 23 discernible. Holdon likens its central tendon to a ruiliuK'nlary cervical rih, its posterior belly to a digitation of the serratus niaj;uus muscle, and its anti-rior belly to a sterno-hye)id ninsele. The subclavian artery extends from one-half of an inch to an inch above the clavicle, in the supra-clavicular fossa, close to tlie external border of the stt'rno- mastoid nniscle, where, by moderate pressure directed downward, backward, and inward, it can readily be compressed against the first rib ; pressure directed other- wise would meet no bony resistance, and bleeding could not be controlled. The carotid arteries are readily found in the neck along the anterior or inner margin of the sterno-niastoid muscle, being covered by its anterior border, particu- larly in the lower part of the neck. The common carotid artery divides opposite the up}ier border of the thyroid cartilage. From this point at the anterior border of the sterno-mastoid muscle, a line drawn to the lobe of the ear indicates the course of the external carotid artery. The position of tlu^ connnon carotid artery is represented by a line drawn from the sterno-clavicular articulation to a point midway between the angle of the lower jaw and the mastoid process. The external jugular vein passes down the neck in a line drawn from the angle of the inferior maxilla to the middle of the clavicU'. By compression of its lower end the vein may be made to stand out j)ronnncntly. Occasionally ajit(/iilo- cephalic branch passes over the clavicle from the cephalic to the external jugular vein. The anterior jugular vein is usually found near the anterior margin of the sterno-mastoid nmscle. The hyoid bone, directly behind the lower border of the chin in the ordinary attitude of the head, may be felt in its entirety through the skin. Tn its upper border are attached the base of the tongue and the geniodiyoid and inylo-hyoid muscles, which form the fiooi- of the mouth. Below the body of the bone are the thyro-hyoid space and membrane, the center of which corresponds to the position of the epiglottis. The greater cornu of the bone is the landmark which locates the origin of the superior thyroid, lingual, and facial arteries. The origin of the superior thyroid artery is just below the level of the greater cornu of the hyoid bone, that of the lingual artery is opposite to the greater cornu, and that of the facial artery is just above. The thjrroid cartilage forms the anterior projection in the neck called " Adam's apple " ; it is larger in men than in women, so that there is increased length of the vocal cords, which have, therefore, in accoi'dance with a well-estab- lished law of phy.sic.s, a lower pitch, thus accounting for the deeper tones of the male. The entire cartilage is subcutaneous, its borders' and cornua being easily traced by the finger. The lateral lobes of the thyroid gland can be indistinctly felt upon each side of the cartilage, and it is said the i)ulsations of the superior thyroid artery may readily be felt at the tip and front of the lateral lobe; this, 24 SURGICAL ANATOMY. however, is exceptional. Below this cartilage is the crico-thyroid space, which is occupied by the crico-thyroid membrane. It is through this membrane that laryn- gotomy is performed, care being taken to hug the upper Ijorder of the cricoid cartilage, so that the incision may be as far as possible from the vocal cords and the crico-thyroid arteries. The vocal cords are situated slightly below a point midway between the deep- est part of the incisura tl\yroidese and the lower border of the thyroid cartilage. The cricoid cartilage is always prominent, and can readily be discerned. It lies opposite the sixth cervical vertebra. Its lower border is on a level with the commencement and narrowest part of the esophagus ; for this reason all l)odies which have entered the pharynx but are too large to pass through the gullet will lodge behind the cricoid cartilage. The cricoid cartilage is just above the level at which the omo-hyoid muscle and the inferior thyroid artery cross the carotid sheath, the muscle being in front of the sheath and the artery liehind. Slightly below the level of this cartilage and beneath the anterior border of the sterno- mastoid muscle is the carotid tubercle, against which the common carotid artery may be compressed. This is the anterior tubercle of the transverse process of the sixth cervical vertebra. The movements of the larynx are frequently overlooked. The larynx rises during deglutition, in singing a high note, and in expiration ; it descends in singing low notes, in inspiration, after deglutition, and during retching and vomiting. AA'hen tlie larynx is moved from side to side, a grating sensation, due to the friction of the superior cornua of the thyroid cartilage against the spinal column, is perceived. The larynx is pu.shed forward in the passage of masses through the lower pliarynx. The sudden upward ru.*h of vomited matter jn-oduces suction upon tlie larynx, drawing out obstinately adherent false membrane and collections of glairy mucus ; this is one reason for giving children emetics in croup. The trachea is situated immediately below the cricoid cartilage. Ordinarily, not more than one and one-half inches of it appear above the sternum ; an inch more, however, may be revealed if the neck be in extreme exten,sion. This usually leaves alwut eight rings in the neck, of whic-li the second, third, and inurtli are covered by the thyroid istlunus. The front of the trachea may lie ime and one-half inches deep at the top of the sternum, owing to the recession of the lower cervical and upper thoracic vertebrpe. Opening of the tracliea to relieve dyspnea is beset witli many difficulties not all demonstrable in llie i-adaver — the .strong and ra])id alternate muscular C(intracti(ins. the heaving larynx, the distended ;ui1eri(ir jugular veins, the flexed neck, the swollen thyrdid isllnnns, llie ilistended thyroid plexus of veins, and, fre(|uently, a middle thyroid artery. .\ll imasious into the trachea should be in the me(lian line, where fewer iniporlanl slrneUires need be severed, ll is often advisable in cases t)f dysjmea, to incise the erii-o-thyroid SURFACE ANATOMY OF THE NECK. 25 membrane, and, if necessary, the cricoid cartilago may l)e divided. If a lnwcr operation be required, it siioidd be done whi'n the jiatient has Ix'coine (|uieleil after rehef of the dyspnea. The back of the neck jjresents, above, the external occipital protuberance and the superior curved ridges of the occipital bone ; below, the spinous i)rocess of the seventh cervical vertebra (vertebra jirominens) and the ligamentum nucha'-, extend- ing lietween the protuberance and tlie spine of the seventh cervical ^•e^teb^a. For an inch below the superior curved ridges of the occipital lione tiic Ibiii cere- bellar fossie of the occiput are not more than one-half of an inch fnun llic surface ; tlieir walls are so thin at times that they may easily be penetrated witli a sharp knife. About an inch below the external occipital protuberance a sharp, narrow instrument could be pushed forward, either above or below the posterior areli of the atlas, thus severing tlie upper end of the spinal cord and destroying life. About one or one and one-half inches on each side of the external occipital protuberance the occipital artery pierces the trapezius muscle, below the superior curved ridge, and passes over the occiput to the vertex ; it is accompanied by the great occipital nerve. The outer margin of the trapezius muscle merges with the shoulder as it passes to it, and forms the graceful outline of the neck so well exhibited in some of the lectures of noted beauties. Deep pressure in llie median line near the occijiut reveals the l:)ifid spine of the second cervical vertebra. The spines of the tliird, fourth, and fifth cervical vertebi'je, because of their shortness and recession, are not readily felt. The spine of the sixth, and more especiall}' of the seventh, cervical vertebra may easily be detected. The fifth cervical spine is opposite the cricoid cartilage and the upper end of tin^^ esophagus ; that of the seventh is behind the apex of the lung, which is higher in women. Congenital cervical fistulee. — A lirief resume of the develojiment of the neck is here introduced in order to explain the mode of occurrence of certain interesting and important congenital defects. The antero-lateral portion of the neck is formed largely from tlie hrtnicJiidl or lisceral arches, four in number on each side, connected po.steriorly witii tlic spinal column, l)ut not at first uniting anteriorly with one ant)tber. These arches are separated from one another by the branchial clefts, also f()ur in nnnd)er on each side, the fourth one being below the last arch. The first or mandibular arch is concerned in the formation of the maxiihe ; it is separated from the second arch by tlie first branchial cleft, Avhich is the only cleft remaining in the adidt. Tlie first branchial cleft persists as the external auditory meatus, middle ear, and Eustachian tul)e. Irregularities in development may lead to the formation of fistulous openings, wliieh are usually found in the vicinity of the" tragus of the ear. 26 SURGICAL ANATOMY. The lower three arches are concerned in the formation of the tissues of tlie neck. The visceral clefts open internally into the pharynx ; no coninuinication of the pharynx with the exterior ever occurs, for a delicate membrane divides the cleft into an inner (pharyngeal pouch) and an outer portion (branchial furrow). The lower three clefts normally disappear, certain traces found in the pharynx and larynx alone remaining. The third and fourth arches are small, are gradually overlapped by the second arch, and lie in a depression known as the sinus cervicalis. It is through imperfect closure of this sinus that most of the congenital cervical fistula occur. These are narrow, epithelium lined tracts, opening externally near the anterior border of the sterno-mastoid muscle. When complete, they open internally into the pharj'ux. If the internal portion of a branchial cleft fail to become obliter- ated, while the outer portion is closed as normally, a pharyngeal or esophageal diverticulum may form. Furthermore, if the cleft become closed externally and internally and an intermediate, unobliterated portion persist, the epithelium lining this cavity may proliferate and undergo various changes, and thus a so-called branchial cyst result. These branchial cysts occur in the submaxillary and supra- clavicular regions and at the borders of the sterno-mastoid muscle. Dissection. — The neck should be extended and made prominent by placing a block beneath the shoulders. An incision should be carried from the symphysis of the lower jaw down the middle line of the neck, to the middle of the top of the sternum ; a second and a third incision should be made, the former along the clavicle to the acromion process, the latter along the lower border of the lower jaw to the angle of the jaw, thence to the lobe of the ear, and behind the ear to the transverse incision made in dissecting the scalp. The face should then be turned away from the side on which the dissection is being made, and retained in position with hooks, the skin being raised and reflected from before backward to beyond the anterior border of the trapezius muscle. The skin covering the side of the neck is thin, quite elastic, and can readily be raised into folds, which always contain the platysma myoides muscle ; these conditions favor the performance of plastic operations. In these respects it differs from the skin over the nape of the neck, which is very dense and adherent and more freely supplied with nerves, but not nearly so well supplied with blood vessels. Carbuncle is usually seen at the lower part of the back of the neck near the median line. The nape of the neck was formerly a common site for the intro- duction of setons and the application of issues. The superficial fascia now exposed is a very thin lamina of areolar and adi- pose tissue, divisible, as elsewlicrc, into two layers, the tleep one being a very deli- PLATE INCISIONS FOR DISSECTION AND LINES FOR VESSELS AND NERVES, 27 PLATE \ External jugular v. Small occipital n.- Mascoid br. of small occipital nr Great auricular n. Posterior jugular v ■ Superficial layer of deep fascia— / .\ ■* , ^ Platysma myoides m. PLATYSMA MYOIDES MUSCLE. 30' DISSFCTIOX OF rilE NECK. 31 cate layer of laminated tissue. Between these twn layers an- Uic ]ilatysma luyoides muscle, the external, anterior, and posterior jugular veins, the sujiertieial branches of the cervical plexus of nerves, and the infra-maxillary branch of the cervico-facial division of the facial nerve. The fat in the superficial fascia above the hyoid bone may be extensively develojieil and produce the eouilitinn known as "ihiuble chin." Dissection. — The superlieial layer of (be superficial fascia should be removed in the manner |)ractised in retlectiiit;- the skin. This disst'ction expo.ses the platysma myoides muscle. The platysma myoides muscle (the superficial cervical), a Ijroad, thin muscle, lies immediately beneath the skin and the superficial layer of the superficial fascia ; it covers the front and side of the neck, extending from tiie summit of the shoulder and front of the chest to the face. Tliis muscle is a member of the pan- niculus carnosus group. It arises from the deep fascia covering the pectoralis major, deltoid, and trapezius muscles, and ascends obliquely forward along the side of the neck, for insertion into the lower border of the lower jaw, the superficial fascia of the cheek, the muscles at the angle of the mouth, and the integument of the chin. The anterior fibers cross those of the opposite side just below the symphysis of the lower jaw, and are inserted into the integument of tiie chin ; the middle fibers are attached to the lower border of the lower jaw ; the posterior fibers are prolonged over the masseter muscle, and are inserted into the super- ficial fascia of the cheek and the muscles at the angle of the mouth. Those fibers passing transversely to the angle of the mouth constitute the risorius muscle. Nerve Supply. — From the infra-maxillary branch of the cervico-facial divi- sion of the facial and the superficial cervical nerves. Blood Supply. — From the vessels I'amifying in the superficial fascia of the neck. Action. — It dra^vs the lower lip downward and outward by contraction of its upper fibers ; when all the fibers are contracted, however, the skin and superficial fascia of the neck lietween the clavicle and lower jaw are raised, being made taut between these two bones ; it also helps to depress the lower jaw, or, if the jaw be fixed, assists the opposite sterno-mastoid muscle in flexion and rotation of the head toward its own side. The anterior edge of the muscle is distinctly visible in emaciated and aged persons, forming, with the platysma of the opposite side, two divergent folds descending from a little l)elow the chin. As the mu.scle dips into a depression above the clavicle, by elevation of skin and fasciae at tlie loot of the neck, it relieves press.ure upon the veins and favors the return circulation. Injuries of the neck, with destruction of considerable portions of the integu- ment and platysma, as in burn.s, areu.sually followed by deformity from cicatricial contraction. Pus in the loose tissues under the platysma may burrow extensively. 32 SURGICAL AXATOMV. descending from the submaxillary region to the upper part of the chest-wall, Avhere pointing may occur. Dissection. — The platysma should now be removed, cutting it across near the clavicle and reflecting it upward to its insertion into the jaw, thus exposing the subcutaneous portions of the superficial branches of the cervical plexus of nerves, tlie infra-inaxillary branch of the cervico-facial division of the facial nerve, and the anterior, external, and posterior jugular veins. The external jugular vein arises in the substance of the parotid gland, and is formed by the union of the jiosterior auricular vein and the posterior division of the temporo-maxillary vein. It runs down the neck in a line drawn from the angle of the lower jaw to the middle of the clavicle, first passing over the sterno- mastoid muscle, and then along its posterior border to tlie root of the neck, there piercing the sujjerficial layer of the deep cervical fascia to enter the subclavian vein in the subclavian triangle. This fascia is so closely attached to the A'ein that at the root of the neck, if the vein be divided, it will remain open. The auricu- laris magnus nerve, a branch of the cervical plexus, accompanies the vein in its upper part, and the superficial cervical branch of the same plexus passes beneath it at about the middle of the course of the vein. The posterior external jugular, transversalis colli, and supra-scapular veins empty into the external jugular vein. Near the angle of the lower jaw the external jugular communicates with the internal jugular vein bj' a large branch, farther down with the anterior jugular, and, at times, with the cephalic vein by a branch (jugulo-cephalic) which passes over the clavicle. The anterior jugular vein occasionallj' empties into the external jugular instead of into the subclavian vein. The external jugular vein contains a pair of valves at its point of entrance into the subclavian, and another pair about one inch or one and one-half inches above this point ; these valves can not prevent the reflux of blood into the external jugular vein, and in certain cardiac and aortic diseases, especially in tricuspid insufficiencj% a pulsation in the external Jugular vein synchronous with the cardiac systole may be observed. The portion of the vein between the valves is dilated ; tins jiortion is called the sinus. The external jugular vein varies in size — when the anterior and posterior jugular veins are large, the external jugular vein is small, and vice versa. In some instances two external jugular veins may be observed ujion each side of the neck. The superficial cervical nerve may, at times, be seen to pierce tlie wall of the vein. Venesection. — Tlie operation of phlebotomy, or venesection, may be per- formed upon the external jugular vein, \\"lien the lower portion of the vein is selected lor the operation, the direction the fibers of the platysma myoides muscle sliould Vie borne in mind, and the incision be made across tbem. They will then retract and pull the wound open, thus allowing the blood to flow freely and 11-:^ PLATE V, \ Small occipital n. br. of small occipital n. .Inframaxillary br. of facial n. Supraacromial br. of cervical plexus Suprasternal br. of cervical plexus Supraclavicular branches of cervical plexus SUPERFICIAL LAYER OF DEEP FASCIA, SUPERFICIAL VEINS AND NERVES, 34 PLATE Supraorbital v Frontal veins Transverse facial Orbital Middle temporal v, Superficial temporal v. (Communication with mastoid \ Occipital V. Angular v. VEINS OF SCALP, FACE, AND NECK. 35 DISSECTWX or THE SFJ'K. 37 avuiilin^- its oxtrava.satioii liciicatli the ijlatvsnia. The vein is incise^l i-iiiUquely, not transviTst'iy, and should nut lie cDiiiiiletely severed, as lieinonhagc from a partially divided vessel is mure copious. The hemorrhage may be cliecked by relieving the pressure applied to the vein at the root of the neck, and by application of a sterile compress over the wound. When the upper portion of the external jugular is selected, the incision should be carried in the line of the fibers of the stcnio- mastoid muscle. The external jugular vein may be selected as one of llie chan- nels for the intra-venous injection of saline solution. A chain of small lyni]ihatie glands (superficial cervical), varying in munber fxiim four to six, lies along the course of the external jugular vein. The posterior external jugular vein commences in the upper and back part of the neck, between the sjjlenius and trapezius muscles, draining this territory and entering the lower jiortion of the external jugular vein. It occasionally receives the occipital vein. In the fetus it drains the intra-cranial region through a vein transmitted by the post-glenoid foramen, the remnant of which vein is the mastoid vein. The tran-sversalis colli and supra-scapular veins frcriuently emjity into the posterior external jugular vein. The anterior jugular vein arises beneath the chin. It is formed by the mental, submental, inferior labial, and inferior hyoid veins, and passes downward, almost to the sternum, in advance of the anterior border of the sterno-mastoid muscle. Here it pierces the superficial layer of the deep cervical fascia, and occupies the interval (supra-sternal intra-aponeurotic space of Griiber) above the sternum, made by the division of the superficial layer of the deep cervical fascia into two layers ; it then turns outward beneath the sterno-mastoid muscle, and enters the external jugular or the subclavian vein. It drains the skin and muscles of the anterior or median region of the neck. In making a subcutaneous section of the sterno-mastoid muscle for the correction of wryneck (torticollis), the teno- tome must hug the under surface of the origins of the muscle closely, otherwise the anterior, external, and internal jugular veins may be injured. There are usually two anterior jugular veins, one upon each side of the median line of the neck, connected just above the sternum by a transverse branch. This branch also occupies the interval between the two layers of the superficial layer of the deep cervical fascia, and being quite large at times, should be borne in mind when performing the low operation of tracheotomy. In labored breathing, due either to laryngeal or tracheal obstruction, these veins will be much dilated, and care will be required in incising the median line of the neck, to prevent opening one or the other. Shoulper part of the pectoralis major muscle and the mammaiy glaml, and communicate with the small cutaneous branches of the upper interco.stal nerves ; the external or supra-acromial branches cross the upper surface of the trapezius muscle and the acromion process, and supply the integument of the upper, outer, and back part of the shouldei'. Herpetic erujitions in the area of distribution of the superficial branches of the cervical plexus (herpes cervico- occipitalis) are occasionally seen. In caries of the cervical vertebrje pain may be referred to the areas of skin supplied by these nerves. It is through the descend- ing branches of the cervical plexus that pain is referred to the neck in carcinoma of the mammary gland. The infra-maxillary branch of the cervico-facial division of the facial nerve emerges from the lower border of the parotid gland, and passes downward and forward under the platysma myoides muscle, which it supplies, and commu- nicates with the sujierticial cervical nerve. The deep cervical fascia, like the deep fascia in other portions of the body, consists of a superficial layer which surrounds the underlying muscles, vessels, and nerves, and of processes prolonged inward to form separate sheaths for the mus- cles and vessels, thus i.?olating and helping to retain them in their ]iro])er positions. It varies in strength, being strongest below tlie angle of the lower jaw, above the clavicle, and in front of the trachea. In studying this fascia it will be found more satisfactory to trace it from behind, where it is attached to the ligamentum nuehse 46 SURGICAL ANATOMY. and the spinous process of the seventh cervical vertebra (vertebra prominens). At the ligamentum nuchse the superficial layer immediately begins as two layers, whicli inclose the trapezius muscle. From the anterior border of the trapezius it passes as a single laj'er across the posterior triangle of the neck to the posterior border of the sterno-mastoid muscle. This portion of the superficial laj'er is attached above to the mastoid process of the temporal and superior curved line of the occipital bone, and below to the clavicle. It is pierced by the external jugular vein directly above the clavicle, behind the clavicular origin of the sterno-mastoid muscle. At the posterior border of the sterno-mastoid muscle it again splits into two layers to inclose the muscle, from the anterior border of which it is continued as a single layer across the anterior triangle of the neck to the middle line, where it joins the corresponding layer of fascia of the opposite side. This portion of the superficial layer is attached above to the lower border of the lower jaw and the styloid process of the temporal bone, and in front to the hj'oid bone. Near the upper border of the sternum this layer of fascia divides into two laj'ers, an ante- rior and a posterior, which are attached respectively to the anterior and posterior margins of the upper border of the sternum. Between these two layers is an interval (the supra-sternal intra-aponeurotic space of Griiber) containing some fat, perhaps one or two small Ij'mphatic glands, the sternal head of the sterno-mastoid muscle, the anterior jugular veins, and the transverse branch connecting them. The la3'er of fascia overlying the sterno-mastoid muscle is continued upon the face over the parotid gland and the masseter muscle as the parotid and masseteric fasciae, which are attached to the lower border of the zj'gomatic arch. The portion of the superficial laj^er covering the trapezius and sterno-mastoid muscles is so thin that their fibers can be seen through the fascia. At the angle of the lower jaw this layer of fascia sends a process inward which is attached to the styloid process, and is known as the stylo-maxillary ligament. This ligament sej)arates the parotid from the submaxillary gland. From the superficial layer two processes are given off, a posterior and an anterior. The posterior process (jjrevertebral fascia) arises from the suj)erficial layer at the anterior border of the trapezius muscle, and covers the splenius, levator anguli scapulas, scaleni and prevertebral muscles, subclavian, vertebral, inferior thyroid, supra-scapular, and transversalis colli ves.sels, cervical trunks of the axillary or brachial plexus, phrenic nerve, and cervical sympathetic nerve. This process of fascia passes lirliiud the cf)iiinion carotid artery, inli'rnal jugular vein, pharynx, and esophagus. It is attached above to the base of tlic skiiU ; below, to tlie first rib, a^ far forward as the anterior margin of the scalenus anticus muscle. To the inner side of this muscle it jiasses downward into the chest over the longus colli muscle and bodies of the vertebrtc. To the outer side of the scalenus anticus muscle it splits to DISSECTIOX OF THE NECK. 47 envelop the subclavian vessels, which it accompanies into the axilla, where, with a process from the costo-coracoid membrane, it forms the sheath of the axillary vessels. As it passes behind the common carotid artery and internal juf;ular vein it reinforces the sheath of these vessels. The anterior process (pretracheal fascia) arises from the superficial layer near the anterior border of the sterno-mastoid muscle, passes beneath the sterno-hyoid and .sterno-thyroid muscles, and in lioiit of the trachea, enveloping the tliyroid gland. It is attached Id tlic first ril), to which it binds the tendon of the omo-hyoid mu.scle. This, with the posterior process just described, and the layer of deep fascia beneath the sterno-mastoid muscle, complete the formation of the sheath of the common carotid artery and internal jugular vein. The portion of the deep cervical fascia wliich envelo]is the trachea and great vessels extends downward along the great vessels into the chest, where it is continuous with the fibrous layer of the pericardium. The superficial laj'er of the deep cervical fascia, with its two dceji processes, divides the neck into three compartments : an anterior, a middle, and a posterior. The anterior compartment, between the superficial layer and the pretracheal fascia, contains the anterior belly of the omo-hyoid, the sterno-hyoid, and sterno-thyroid muscles. The middle or visceral compartment, between the pretracheal and ] ire- vertebral fasciae, contains the thyroid gland, trachea, and esophagus. The posterior or muscular compaiiment, between the prevertebral fascia and the superficial layer, contains the prevertebral muscles, scaleni, levator anguli scapulte, and the muscles of the back of the neck, excepting the trapezius. Dr. Allan Burns first called the attention of the profession to the Ijarrier at the upper opening of the chest, formed by the attachment of the deep cervical fascia to the sternum, the first rib, and the clavicle, supporting the soft parts and preventing them from yielding to the pressure of the atmosphere during ins])ira- tion. The internal jugular, subclavian, and innominate veins are so closely attached to the adjacent bones and muscles by the deep cervical fascia that they gape when divided, thus permitting air to enter. In operations on the neck, mIuii these veins are exposed and division is necessary, it is best to ligate tliem before severing them. Abscess. — In order to become familiar with the course pus jiursues in the neck, a correct knowledge of the attachments of the deep cervical fascia is neces- sary. A collection of pus situated beneath the superficial layer of the deep fascia at the side of the neck may burrow into the axilla, and, vice versa, one in the axilla may work its way into the neck ; if situated beneath the layer of deep fascia (pos- terior process or prevertebral fascia) covering the scaleni muscles, and attached to the first rib as far forward as the anterior border of the anterior scalene muscle, it mav burrow into the chest cavity, reaching the posterior mediastinum, or follow 48 SURGICAL ANATOMY. the sheath of the subclavian vessels into the arm-pit ; if situated beneath the super- ficial layer of the deep fascia in the anterior portion of the neck, it may enter the chest, being guided into the anterior mediastinum by the pretracheal fascia ; if it lie beneath the anterior process, or pretracheal fascia, it may extend into the posterior mediastinum. Abscesses of the neck have frequently burst into the esophagus or trachea, and even into the pleural sac ; the great vessels at the side of the neck have in some instances been entered. " In one remarkable case, reported by Mr. Savory, not only was a considerable portion of the common carotid arterj' destroyed by the abscess, but a still larger portion of the internal jugular vein and a large part of the vagus nerve were also destroyed " (Treves). Mr. Jacobson (Hilton, on " Rest and Pain ") states that " communication between abscesses and the deep vessels has usually taken place beneath two of the strongest fasciaj in the body — the deep cervical and the fascia lata." Prompt evacuation is indicated by the possibility that these absce.sses may take one or more of the foregoing undesirable courses. Dissection. — The superficial laj'er of the deep fascia should be removed by making incisions similar to those made for the removal of the skin and the super- ficial foscia, being careful not to destroy the superficial branches of the cervical plexus of nerves which pierce it. The removal of the superficial layer will expose its two processes and other underlying structures. Cervical plexus. — Before taking up the description of the muscles of the neck and its dissection proper, the origins of the superficial branches of the cervical plexus of nerves should be studied. This plexus is formed by the communi- cation of the anterior divisions of the upper four cervical nerves, all of Avhich communicate with the sympathetic nerve. It lies viiider the sterno-mastoid muscle, opposite the upper four cervical vertebrae, and rests upon the levator anguli scapulae and scalenus medius muscles. Its branches consist of a superficial and a deep set. The superficial branches, as previously described, are the auricu- laris magnus, the occipitalis minor, the superficial cervical, the supra-sternal, the supra-clavicular, and the supra-acromial, all running to the skin and subcutaneous structures. The deep branches are the phrenic, the communicantes hypoglossi, communicating, and muscular. The superficial branches alone concern us in this stage of the dissection. They emerge at the side of the neck from beneath the ])osterior border of the sterno-mastoid muscle, at the level of tlie upper border of the thyroid cartilage. Till' sterno-cleido-mastoid muscle, the largest muscle of the neck and its most important landmark, arises by two heads: one, round and tendinous, from the front of the uppei" portion of tlu; sternum ; the other, flattened, partly muscular and partly tendinous, from the inner one-third of the ui)pcr surface II-4 PLATE X, External carotid Internal maxillary Temporal v. Posterior auricular a Posterior auricular v. Complexus Stylo-hyoid m. Posterior belly of digastric m. Occipital a. .Lingual V. Lingual a. Facial V. Anterior bellies of digastric muscles Levator anguli scapulae m Ttansvcrsalis colli v. Serrotus magnus Postencr belly of omo-hy Scalenus modius m Suprascapular a. Suprascapular v. Subclavian a. {3d portion) Transversalis colli a. Stcrno-thyroid m. SUPERFICIAL STRUCTURES OF NECK. 50 PLATE XI, Facial n. Posterior auricular n.and v. Nerve to stylo-hyoid m.and posterior belly of digastric m, Hypoglossal n. Descendens hypoglossi n. Lingual V. SulDmaxillary gland Mylo-liyoid n. Superficial cervical n Posterior thoracic n Suprascapular n. Brachial plexus SUPERFICIAL 8 - S OF NECK. 51 DISSECTION OF THE NECK. r^S of the clavicle. These two heads unite at a variable distance from tlic clavicle. Tiie muscle is inserted into the external surface of the inastnid pi'occss (if llie temporal bone by a strong, thick tendon, and into the outer twothirds of tlie superior curved line of the occipital bone by a thin aponeurosis. Tlie muscle is narrower in the middle than at either extremity. Its anterior border is the surgeon's guide in the ligation of the common, external, and internal carotid arteries, the superior thyroid, lingual, facial, and occipital arteries at their origin, and the inferior thyroid artery as it enters the thyroid gland ; in ex])osing tlu' s]iiiia] acces- sory nerve ; upon the left side in tlu; operation of esophagotoni}^ ; and in all other operations upon the front of the side of the neck. The jiosterior border of the muscle is a guide in the ligation of the subclavian and vertebral arteries ; the inferior thyroid artery at its origin ; in stretching the spinal accessory nerve, the superficial branches of the cervical ])lexus, and the cervical trunks of the brachial or axillary jilexus ; and in all other operations upon the posterior portion of the side of the neck. Blood Supply. — From the superior, middle, and inferior sterno-mastoid arte- ries. The superior sterno-mastoid is a branch of the occipital artery, and enters the muscle with the spinal accessory nerve ; the middle sterno-mastoid is a branch of the superior thyroid artery, and enters the middle one-tliird of tlie muscle, after crossing the .sheath of the common carotid artery in the sujx'rior carotid triangle on a level with the thyroid cartilage ; the inferior sterno-mastoid is a branch of the supra-scapular arter}', and enters the lower one-third of the muscle. The muscle also receives a twig from the posterior auricular artery. Nerve Supply. — From the spinal accessory and the anterior divisions of the second and third cervical nerves. Action. — The combined action of the sterno-mastoid muscles is to draw the head forward, elevating the chin at the same time ; when one muscle alone acts, it turns the face to the opposite side, cooperating with the opposite splenius muscle ; it also draws the head toward the shoulder of the same side. If the head be fixed, these muscles will raise the sternum, as in forced respiration. Torticollis. — Permanent contraction of one of the sterno-mastoid muscles con- stitutes torticollis (wTyneck). The deep muscles of the neck — splenius capitis et colli, complexus, superior oblique, inferior oblique, and rectus capitis posticus major — may also be involved in this deformity, particularly in cases of long standing. In true congenital wryneck, due possibly to faulty position of thi' fetus in utero, the sterno-mastoid muscle has, in some instances, been found to be abnor- mally short. Some cases of wryneck are doubtless due to laceration of the muscle during birth, with subsequent cicatricial contraction. Facial asymmetry 54 SURGICAL ANATOMY. and deformities of tlie cervical portion of the spinal column may be associated with long-standing cases of torticollis. In spasmodic wryneck the sterno-cleido-mastoid muscle is at fault, through the spinal accessory nerve, though some of the muscles previously mentioned, as well as the trapezius muscle, may be involved ; resection of the spinal' accessory and branches of the posterior divisions of the cervical nerves has been performed in these cases. It should not be forgotten that irritation of some of the cervical nerves, as by inflamed lymph glands and caries of the cervical vertebrae, may cause a faulty position of the head which may be mistaken for torticollis due to other conditions. TRIANGLES OF THE NECK. The sterno-mastoid muscle, owing to its oblique position, divides each half of the neck into two triangles — the anterior and posterior common triangles. The Anterior Common Triangle is bounded above by the lower border of the body of the lower jaw and a line extending from the angle of the lower jaw to the mastoid process of the temporal bone ; in front, by a line extending from the symphysis of the lower jaw to the middle of the supra-sternal notch, or by the median line of the neck ; and behind, bj' the anterior border of the sterno- mastoid muscle ; its apex is below — at the sternum. This triangle is subdivided into three smaller ones by the posterior belly of the digastric muscle and the anterior belly of the omo-hyoid muscle. The three triangles, from above down- ward, are the submaxinary or diffastric, the superior carotid, and the inferior carotid. The Posterior Common Triangle is bounded in front by the posterior border of the sterno-mastoid muscle ; behind, by the anterior border of the trapezius muscle ; and below, by the clavicle ; its apex is above — at the occiput. This triangle is subdivided into two smaller triangles I\y the posterior belly of the omo-hyoid muscle, the upper, the larger of the two, being known as the occipital, and the lower, the smaller, as the subclavian, triangle. The author would here remind the reader that the boundaries of these tri- angles by muscular margins do not harmonize witli the enumeration of their contents, many of wliich are overlapped by the boundary muscles, particularly the sterno-mastoid, and are, therefore, really outside the spaces to which they are thus inaccurately accredited. The most accurate dividing line between the anterior and posterior triangles would be the middle line of the sterno-mastoid muscle rather than its two borders. Dissection. — Having mai)]>ed out flic triangles into wliirli (lie side of the neck is divided, tlic iii the cervical i)()rtion of the spinal cord as low as tlie sixth or seventh cervical nerve. The spinal portion passes upward througli the spinal canal between the ligamentum denticulatum and the posterior roots of the spinal nerves, and enters the cranial cavity through the foramen magnum to join the accessory portion. The two por- 58 SURGICAL ANATOMY. tions emerge from the cranial cavity together through the jugular foramen, just external to which the accessory portion joins the ganglion of the root of the pneu- mogastric nerve. The spinal portion then passes successively behind the internal jugular vein, the posterior belly of the digastric, and the stylo-hyoid muscle, to enter the upper part of the sterno-mastoid muscle, entering its under surface mid- waj' between its two borders and one inch below the tip of the mastoid process. It leaves the muscle at the middle of the posterior border. AVithin the sterno- mastoid muscle it is joined by a liranch of tlie second cervical nerve. The superior sterno-mastoid artery accompanies the nerve into the muscle, which it supplies. Having pierced the sterno-mastoid muscle, it crosses the occipital triangle oblicjuely downward and backward to enter and supply the trapezius muscle. For the relief of spasmodic torticollis, resection of a portion of the spinal accessory nerve may be performed. The sj^inal accessory nerve may be exposed at one of three points — just before it enters the sterno-mastoid muscle, in the substance of the muscle, or at the posterior border of the muscle. Of these methods, the first is the best. To expose the .nerve before it enters the muscle, the head and neck should be well extended, and an incision made along the anterior border of the upper one-third of the muscle, dividing skin, sui^erficial fascia, some fibers of the platysma myoides muscle, and the superficial layer of tlie deep fascia, avoiding, if possible, the external jugular vein. Displace the sterno-mastoid muscle out- ward, when the nerve will be found beneath the prevertebral fascia and passing from beneath the sheath of the internal jugular vein, to enter the muscle about an inch below the tip of the mastoid process. The prominent transverse process of the atlas lies above the nerve, and serves as a deep guide in locating it. To expose the nerve in the substance of the sterno-mastoid muscle an incision should be made in the middle line of the nmscle. Tlic muscle fibers are separated and the nerve exposed as it passes through the deejier portion just above the level of the thyroid cartilage. The skin, superficial fascia, fibers of the platysma myoides muscle, superficial layer of the deep fascia, the sterno-mastoid muscle, and the superior and middle .sterno-mastoid arteries M'ill lie cut. The external jugular vein should, if possible, be avoided. To expose the nerve along the posterior border of the muscle carry an incision along the middle one-third of that border. The skin, superficial fascia, fibers of the platysma myoides muscle, and the superficial layer of the deep fascia will be divided. The occipitalis minor nerve will be seen running upward along the pos- ti'rior border of the sternp-mastnid muscle. Trace this nerve downward, and locate tlic spinal acces.sory nerve as it emerges from the postci'ior l)nr(l('r of the sterno- mastoid muscle on a level wit): tlie upiier border of the thyroid cartilage. The middle sterno-mastoid artery. — The middle .sterno-mastoid artery will DISSECTION OF rilK NECK. 59 at times be of considerable size and extend well into, if not across, the occiiiital triangle, supplyinehind the scalenus anticus muscle, but it may pass in front of that muscle or between its fibers. Normally, the third part of the subclavian artery does not give off any branches ; the poste- rior scapular, however, one of the terminal branches of the transversalis colli arterj'-, often arises from this portion of the vessel ; the transversalis colli artery itself, or the supra-scapular artery, may arise from the third jwrtion of tlie subclavian artery. Tlie .subclavian vein occupies a position below and anterior to tlie artt'ry, not being visible frequently in a dissection of the subclavian triangle. It lies upon the first rib, in front of the anterior scalene muscle, and bcliind the clavicle. Passing downward over the anterior scalene muscle, beneath the posterior process of the deep fascia, is the phrenic nerve, which enters the chest through its upper opening, and Ix'twecn the sul)clayian artery and vein. Iiuiniing through the upper and outer part of the triangle, above and external to the suliclavian artery, are the three cervical trunks of the axillary or brachial plexus of nerves, which emerge at the side of the neck from between the anterior and middle scalene muscles. In the opera- DISSECTION OF THE NECK. 61 tion of ligation of tlie tiiinl jMH-tion of tlic suliciaviaii artery, tlic upper trunk of tlie plexus may be mistaken fur the artery, and the lii^^aluro passed around it. This trunk is, therefore, a \ery useful guide in locating the artery, and should ahvays be kept in mind. X few lymphatic glands, which arc continuous with the axillary lymphatics, arc found in this space. These glands should always be removed in the radical ojteration for removal of carcinoma of the mannnary gland. The triangle is also crossed by the supra-scapular and posterior thoracic nerves and the nerve to the subclavius muscle. The y?oor of the trianylc is formed by the scalenus medius and posticus muscles, the first rib, and the upper digitation of the serratus magnus muscle. The inferior carotid triangle is bounded in front by the median line of the neck; behind, l)y the anterior l)order of the stcrno-cleido-mastoid muscle; and above, by the anterior belly of the omo-hyoid muscle. The roof is formed by the skin, the superficial fascia, which contains the platysma myoides muscle, and the descending branch of the superficial cervical nerve, and by tlie superficial layer of the deep fascia. The' outer margins of the sterno-hyoid and sterno-thyroid, and the anterior margin of the sterno-mastoid muscle cover the more important con- tents of the triangle, and should be drawn aside before dissecting the deeper struc- tures. Contents of the Triangle. — The common carotid artery (not strictly in the triangle, as the vessels lie under the margin of the sterno-mastoid muscle, but so closely related to the contents of the triangle that mention of it here is proper), the internal jugular vein, and the pneumogastric nerve, all three inclosed in a common .sheath, in front of which are tilaments of nerves derived from the loop of com- munication between the descendens hypoglossi, a branch of tlie hypo-glossal, and the communicantes hypoglossi ner^^es, which are deep branches of the cervical plexus ; behind the sheath of the vessels are the sympathetic nerve and its cardiac branches. Upon the inner side of the sheath of the vessels are the lateral lobe of the thyroid gland, the trachea, the lars'^nx, the esophagus, the inferior or recurrent laryngeal nerve (motor nerve of the larynx), which occupies the groove between the trachea and the esophagus, and the terminal portion of the deep chain of cervical lymjjhatic glands. To the outer side of the .sheath of the vessels, running over the scalenus anticus muscle, is the phrenic nerve. The inferior thyroid artery, a branch of the thyroid axis, passes upward and inward through this space to the outer side of and then behind the sheath of the vessels. Situated deeply in the interval between the longus colli and the scalenus anticus muscle, and behind the sheath of the vessels, are the vertebral artery and its accompanying vein. In this triangle the relation between the internal jugular vein and the common carotid artery- differs upon the two sides of the neck ; upon the right side the vein 62 SURGICAL ANATOMY. is a little to the outer side of the artery, the tAvo vessels being in the lower part of the triangle, separated by a narrow interval, while on the left side it lies closer to the artery and somevyhat overlaps it. The floor of tJie triangle is formed by the longus colli and scalenus anticus muscles. The superior carotid triangle is bounded above by the posterior belly of the digastric muscle ; behind, by the anterior border of the sterno-mastoid muscle ; and below, by the anterior belly of the omo-hyoid muscle ; its apex is directed toward the median line of the neck. Its roof is formed by the skin, the superficial fascia, the platysma mj'oides muscle, and the superficial layer of the deep fascia. Contents of the Superior Carotid Triangle. — These are : The common carotid artery and its terminal divisions, — the external and the internal carotid, — the internal jugular vein, and the pneumogastric nerve ; these are all inclosed in a common sheath, the vein lying to the outer side of the artery and the nerve between, and on a plane posterior to both, resembling the ramrod in a double-barreled gun. The common carotid artery usually divides into the external and internal carotid arteries, on a level with the upper border of the thyroid cartilage ; division may, however, take place below or above this point. In tliis triangle the external carotid arteiy gives off the superior thyroid, lingual, facial, occipital, and the ascending pharyngeal artery, all of which, excepting the occipital, are accompanied by their corresponding veins on their way to empty into the internal jugular vein. Passing downward in front of the carotid sheath is the descendens hypoglossi nerve, and behind the sheath, the sympathetic nerve. To the outer side of the sheath, above, is the spinal accessor}' nerve, wliicli pierces the sterno-mastoid muscle ; to the inner side of the sheath is the superior laryngeal nerve, a branch of the pneumogastric, accompanied by the superior laryngeal artery, a branch of the superior thyroid arterj'. Both the superior laryngeal artery and the internal laryngeal branch of the superior laryngeal nerve enter the larynx through the thyro-hyoid mem- brane. To the inner side of the sheath of the vessels, and a little lower, the superior thyroid artery and the external laryngeal nerve, a branch of the superior laryngeal nerve, are seen passing beneath the sterno-th3'roid muscle. The hypo- glossal nerve is seen in the upper part of the triangle, curving around the occipital artery at its origin from the external carotid, and crossing over the external and internal carotid arteries. ITpon the inner side of the triangle are the upper part of the larynx and the lower jinrtiim of the idiarynx. In the deep jiart of the ti'iangle, to the inner side of the slieath of the vessels, are seen the pharynx, the esophagus, and the dee]> cliain of the cervical lymphatic glands, the terminal portion of which iias lieen observed when dissecting the inferior carotid triangle. DISSECT/OX OF THE NECK. 63 The ^miH'rior carotid is the triangle of clcdimi for the liirutiou of the eoninuui CiU'otid urtery, the artery being more superlicinl ami aeeessil)le here. Crossiii;;- tlie sheath of tlie vessels in this tritingle is the middle sterno-mast(ud, a small hraneh of the superior thyroid artery, which is severed in the ligation of the common carotid artery in this triangle. The floor of the trlungle is formed l)y the (hyro-hyoid musele, the hyo-glossus muscle, and the middle and inferior constrictor niuscles of the pharynx. The submaxillary or digastric triangle, the uppermost of the three anterior triangles, is bounded above by the lower border of the body of the lower jaw, and a line drawn from the angle of the lower jaw to the mastoid process of the temitoral bone; below, by the posterior bellj^ of the digastric and the stylo-hyoid muscle, and the line of these muscles extended to the median liui- of the neck ; and, in front, by the middle line of the neck. Its niuj is formed by the skin, the super- ficial fascia, the platysma myoides muscle, and the superficial layer of the deep fascia. The portion of the deep cervical fascia helping to form the roof of this triangle is verj'^ strong. Contents of the Subjiaxillary Triangle. — The .stylo-maxillary ligament, a process of the deep cervical fascia which extends from the styloid ])rocess of the temporal bone to the angle of the lower jaw and separates the submaxillary and parotid salivary glands, divides the submaxillar}' or digastric triangle into two portions, an anterior and a posterior. The posterior jjortion contains a part of the external carotid artery, embedded in the substance of the parotid gland, the internal carotid artery, the internal jugular vein, the i)neumogastric, glosso-pharyngeal, hypo-glossal, and sympathetic nerves, the origins of the stylo-glossus and stylo- pharj'ngeus muscles, and the stylo-hyoid ligament. The last three of these struc- tures, with the glosso-pharyngeal nerve, pass into the anterior part of the triangle between the internal and external carotid arteries. In addition to the terminal portion of the stylo-pharyngeus and stylo-glossus muscles the anterior portion contains the stylo-hyoid ligament and the glosso-pharyngeal nerve, which pass from the posterior portion, the submaxillary gland, tlie facial artery and vein, the ascending palatine, tonsillar, submaxillary, and submental branches of the facial artery, all of which arise within the triangle, the hypo-glossal neiwe, the mylo- hyoid nerve, the raylo-hyoid arter\', and lymphatic glands. A chain of lymphatic glands, ten to fifteen in number, is found below the body of the lower jaw. These glands belong to the superficial cervical lymphatics, and are known as the sub- maxillary lymphatic glands. In malignant growths of tlie li]), lower jaw, tongue, or oral and pharj'ngeal mucous membrane, this chain of glands will soon become infected and should always be removed, whether enlarged or not. In the opera- tion for the removal of a malignant growth involving the areas whicli these glands 64 SURGICAL ANATOMY. di-ain, the first step should consist in the removal of the submaxillary lymphatic glands of both sides of the neck, and, in some instances, of the submaxillary salivary gland ; the final step consists of the removal of the growth. Tuberculosis of these glands is a not uncommon condition, because of the large area from which they receive lymph ; infection from inflammatory affections of the pharyngeal, nasal, and oral mucous membranes, as well as from carious teeth, is very frequently the cause of disease of these glands. An extensive cervical cellulitis, known as Ludwig's angina, may originate from septic processes in the submaxillary lym- phatic glands. The floor of the submaxillary triangle is formed by the mylo-hyoid muscle, the anterior belly of the digastric, the hyo-glossus, the superior constrictor, and a small portion of the middle constrictor muscle of the pharj-nx. Dissection. — The roof of the triangle having been reflected in removing the superficial layer of the deep cervical fascia, the submaxillary salivary gland, with the exception of its upper j^ortion, which is hidden by the body of the lower jaw, will now be seen. The gland is surrounded by a fibrous capsule, which is derived from the superficial layer of the deep fascia. Displace the submaxillary gland up- ward upon the face, holding it tliere Avith hooks while further dissection of the triangle is made. In displacing the gland avoid severing the facial vein, which passes over it, and the facial artery, which passes through the groove on its deep surfaces. The lingual triangle. — The portion of the submaxillary or digastric triangle, through which the lingual artery runs, is frequently spoken of as the lingual triangle. In relation with the triangle are the submaxillary gland, the posterior belly and the tendon of the digastric muscle, the hypo-glossal nerve, the hyo- glossus muscle, and the middle constrictor muscle of the pharynx. This sub- division of the submaxillary triangle is bounded above by the hypo-glossal nerve, posteriorly by the posterior belly of the digastric muscle, and anteriorly by the mylo-hyoid muscle ; its rooj is formed by the submaxillary gland, and its floor by the hyo-glossus and middle constrictor muscle of the pharynx. In ligating the lingual artery an incision is carried above and parallel with the greater cornu of the hyoid hoxiQ ; the skin, the superfic'ial fascia, the platysma myoides muscle, and the superficial layer of the deep fascia are divided, and the submaxillary gland is expo.sed. The gland is lifted upward, when the artery will be found beneath the hyo-glossus muscle and beneath the interval between the hypo-glossal nerve and the tendon of the digastric muscle. In making the incision through the hyo-glossus muscle care must be observed to avoid wounding the middle constrictor muscle, division of which would open the pharynx. It is not necessary to cut the hyo-glossus, as the artery is readily secured before it passes beneath that muscle without endangering the pharj'nx. DISSECrtOX OF THE NECK. 65 Dissection. — Divide the .stenio-inastoid muscle at about its mitldle, and reflect the two portions. This exposes the descendens hypoglossi nerve, wliidi lies niKin the sheath of tlie vessels, the comnninicnntes hypoglossi nerves, the ansa hypoglossi, the tendon of the oino-hyoid muscle, the sheath of the vessels, the spinal accessory nerve, the phrenic nerve, the cervical plexus, the anterior scalene muscle, and a portion of the subclavian vessels and some of their branches. The sj)inal acces- sory and phrenic nerves, the cervical plexus, the anterior scalene muscle, and the subclavian vessels are covered by the posterior portion of the two ])r<>cesses of the deep cervical fascia (prevertebral), overlaid by some areolar and fatty tissue. Re- move the fat and areolar tissue with the layer of fascia (prevertebral) covering the structures just named, inferior thyroid, and the vertebral .supra-.scapular, transversalis colli, and vertebral arteries. THE CERVICAL PLEXUS OF NERVES. The cer\acal plexus is formed by the anterior branches of tlie upper four cer- vical nerves. It is situated in the upper part of the neck, beneath the stcrno- mastoid muscle, and rests upon the scalenus medivis and levator anguli scapulse muscles. It differs from the axillary or brachial plexus in resembling a network rather than a bumlle of cords. Each nerve, excepting tlie first, divides into an ascending and a descending branch ; these unite with similar parts of the contigu- ous nerves, thus forming a plexus. The branches of the plexus are divided into a superficial and a deep set ; the superficial set of branches has been described with the superficial fascia of the neck. The deep set of branches is, for conveni- ence, divided into an internal and an external series. The internal series includes the phrenic, communicantes hypoglossi, muscular, and communicating branches; the external series includes muscular and communicating branches. The phrenic nerve, the internal respiratory nerv-e of Bell, sujjplies the diaphragm. It arises from the third and fourth cervical ner^^es, and receives a communicating branch from the fifth. It passes downward and inward over the anterior surface of the anterior scalene muscle, beneath the omo-hyoid muscle, the transversalis colli and supra-scapular arteries, and the thoracic duct (left side), and enters the upper opening of the chest behind the subclavian vein, and in front of the subclavian arterA-. It then crosses in front of the internal mammary artery, irom without inward, and the root of the lung, and pa.sses through the middle mediastinum between the mediastinal layer of the pleura and the pericardium, to reach the diaphragm, which it pierces for final di.stribution upon its lower surface. At the lower part of the neck it is joined by a filament of the sympathetic nerve, and at times by a branch from the nerve to the subclavius muscle. In the chest it S— II -T 66 SURGICAL ANATOMY. is accompanied by the arteria comes nervi plirenici, a branch of the internal mam- mary artery. The origin of the phrenic nerve is mainly from the fourtli cervical segment of the spinal cord, which is situated behind the upper part of the body of the fourth cervical vertebra, and the fact that this nerve is the one which innervates the diaphragm, explains the fatality due to injury of the spinal cord through fractures and dislocations of the upper cervical vertebrae. The communicantes hypoglossi (communicantes noni) arise from the second and third cervical nerves, pass downward to the outer side of the internal jugular vein, then cross in front of the vein, and join the descendens hypoglossi, a branch of the hypo-glossal nerve, in front of the sheath of the blood vessels, forming the loop known as the ansa hypoglossi. Tlie descendens and communicantes hypoglossi supply the depressor muscles of the hyoid bone and larynx — namely, the sterno- hyoid, sterno-thyroid, and omo-hyoid muscles. This loop (ansa) may be behind the internal jugular vein, and within or outside the sheath of the vessels. The muscular branches of the internal series arise from the first, second, third, and fourth cervical nerves ; they supply the rectus capitis anticus major and minor, rectus lateralis, and longus colli muscles. The communicating branches of the internal series connect the cervical plexus with the sympathetic, jmeumogastric, and hj'po-glossal nerves. The muscular branches of the external series supply the sterno-mastoid, the trapezius, the levator anguli scapula?, and the scalenus medius muscle ; the branch to the sterno-mastoid muscle arises from the second cervical nerve ; the branches to the levator anguli scapulte, trapezius, and scalenus medius muscles from the third and fourth cervical nerves. The communicating branches of the external series connect the cervical plexus with the spinal accessory nerve in the sterno-mastoid muscle, in the occipital triangle, and lastly beneath the trapezius muscle, forming the subtrapezial plexus. Pain in one or more of the areas supplied by the various sensory branches'of the cervical nerves may be caused by caries of the cerAdcal vertebroe. Irritation of these nerves produces pain or spasm of the muscles in the regions supplied by the posterior branches of the nerves, as well as in those supplied by the cervical and brachial plexuses. ' Next examine the carotid sheath and the .structures in relation with it. Tlie Carotid Sheath is formed by the division of the superficial layer of the deep cervical fascia whicli jiasses beneath the sterno-mastoid muscle, by the jire- vertebral and ]>r( •tracheal fascia\ It is diviiled by sei)ta into three compartments: PLATE XII External carotid a. First portion of lingual a. Inferior dental n Facial n. Spinal accessory n anterior to sterno-mastoid in Internal carotid a Spinal accessory n. posterior to sterno mastoid m. and superficial branches of ^ cervical plexus- - Inferior thyroid a. at origin and vertebral a. Brachial plexus -/- 3d portion of subclavian a Facial a. Second portion of lingual a. Superior thyroid a. Common carotid a, in superior carotid triangle Common carotid a. in inferior carotid triangle Innominate a. LINES OF INCISION FOR EXPOSURE OF ARTERIES AND NERVES. 67 PLATE XIV, Temporal v, Posterior auricular artery and nerve Posterior auricular v. Internal maxillary v, External carotid a. Superior sterno-mastold a. Occipital a. Ascending pharyngeal a. Facial a. Facial V. Suporficlat cervical a/ Posterior scapular Superficial cervical v Posterior scapular Transversalls coll Transversalis colli a Subclavi::n a (3d portion) Suprascapular Communicating v. Anterior jugular v. Bifurcation of innominate a. Subclavian a. (1st portion) Vtriebral a. Inferior sterno-mast'iJ a. Subclavian v. Suprascapular ^ VESSELS AND NERVES OE NECK, 70 PLATE XV. Posterio auricular artery end nerve Sterno-mastoid m. Splenius ccpitis m Complex.us m. Facial n, Norve to stylo-liyoid m.and posttirior bolly of digastric m. Posterior belly of digastric rr., Stylo-hyoid m. Superior constrictor m.of pharynx Middle constrictor m.of pharynx Whartor's duct Hyoglossus m. Posterior thoracic n. Posterior belly of omo-hyoid mf Serralus magnus m' Scalenus medlus m. Suprascapular n.' Brachial plexus of nerves' Lower trunk of brachial plexus Upper trunk of brachial plexus Middle trurlt of brachial plexus Ant-div.7th cervical n. no-mastoid m. Recurrent iaryngoal n. Sterno-mastoid m. Scalenus anticus m. Anl.div.6th cervical n. MUSCLES AND NERVES OF NECK. 71 DISSECTIOX OF Tin-: XECK. 73 the inner contains the common carotid artery, the outer the inteiiial jugular vein, and tlie posterior tlie piicuniogastrie nerve. Tlie descendens hypoglossi nerve (descendens noni) is usually seen lying in front of the carotid sheath, Init occasionally it lies within the anterior wall of the sheath. It is given off from the liypo-glossal nerve as the latter Avinds around the occipital artery. It is not a truu hranch of the hypo-glossal nerve, its fibers origi- nally arising from the cervical plexus and running with the trunk of the hyj)o- glossal nerve for a shoi't distance. It eonnnunicates with the communicantes hypoglossi, deep branches of the cervical plexus, thus forming a loop known as the ansa hyjioglossi, which supplies the sterno-hyoid, sterno-thyroid, and both bellies of the omo-hyoid muscle. Lymphatic glands. — In relation with tlie outer wall of the sheath of the vessels, observe the deep chain of lymphatic glands; these glands arc in commu- nication with the superficial chain, and therefore in enlargement of the latter the deep chain is more or less involved. Every surgeon who has had experience in the removal of- glandular tumors of the neck appreciates this fact when forced to carry the dissection to the extent of exposing the carotid sheath for some distance if he Avould remove all enlarged glands. In cases where it is not possible to make a good exposure and dissect Avith safety around the vessels by simply displacing the sterno-mastoid muscle, it will be necessary to divide the muscle. In making a difficult dissection in a region rich in important structures success is obtained only by having a good exposure, which necessitates a large wound. Dissection. — Remove the deep chain of lymphatic glands together with the fat and connective tissue around them, and lay ojjen the sheath, when the carotid artery, the internal jugular vein, and the pneumogastric nerve will l)e brought into view. The internal jugular vein lies to the outer side of the common carotid artery, while the pneumogastric nerve lies between the vein and artery in a jdane posterior to both. The internal jugular vein is the continuation of the lateral sinus, and begins at the jugular foramen, where that .sinus is joined by the inferior petrosal sinus. The vein is somewhat dilated at it origin, this enlargement constituting the so-called bulb or sinus, which lies in the jugular fos.sa. At the jugular foramen the vein lies behind and external to the glosso-pharyngeal, pneumogastric, and spinal accessor^' nen^es. It jiasses down the side of the neck, at fir.st beneath and external to tlie internal carotid artery, then on the outer side of the internal carotid, and, finally, on the outer side of the common carotid artery. It terminates by joining tlie subclavian vein just external to the upper margin of the sterno- clavicular articulation to form the innominate vein. It occupies the outer com- partment of the carotid sheath, and is separated from the common carotid artery 74 SURGICAL ANATOMY. and pneumogastric nerve by septa. At the lower part of the iieek the internal jugular veins observe a slightly different course. At its termination the right internal jugular vein leaves the right common carotid artery to join the subclavian vein, forming a triangular interval between the artery and vein, while the left internal jugular vein turns forward to join the subclavian vein, and overlaps the left common carotid artery at the root of the neck. The internal jugular vein has a pair of valves about three-fourths of an inch from its termination. Opposite the angle of the lower jaw a communicating branch from the external jugular vein and some pharyngeal veins empty into it. Near the level of the greater cornu of the hyoid bone it receives the facial and lingual veins ; lower, the superior thyroid vein ; and opposite the cricoid cartilage, the middle thyroid vein. The common carotid artery. — The right and left common carotid arteries are dissimilar in origin, but occupy similar positions in the neck (for this reason but one artery will be descriljed). The right common carotid arises from the innominate artery behind the ujjper margin of the right sterno-clavicular articula- tion ; the left common carotid arises from the highest part of the transverse portion of the arch of the aorta. As the left common carotid artery arises within the chest, it is the longer of the two vessels ; it may be divided into a thoracic and a cervical portion. The thoracic portion of the left common carotid artery will be described with the chest. The course of the common carotid, external carotid, and internal carotid arteries when the face is turned slightly to the opposite side, is represented by a line drawn from the sterno-clavicular articulation to a point midwaj' between the angle of the lower jaw and the mastoid process of the temporal bone. That por- tion of the line below the level of the greater cornu of the hyoid boire indicates the course of the common carotid artery, and that part above the hyoid bone indi- cates the position of the internal carotid and external carotid arteries. The external carotid deviates slightly from this line toward the angle of the lower jaw. At the lower part of the neck the common carotid artery is situated deeply beneath the sternal origin of the sterno-cleido-mastoid, the stcrno-hyoid, and the sterno-thyroid muscle, being separated from its fellow by the trachea, which is about an inch in width. Thence it ascends in the inner compartment of the sheath of the vessels, beneath the anterior border of the sterno-cleido-mastoid muscle, to terminate opposite the upper border of the thyroid cartilage by bifurcat- ing into tiie external and internal carotid arteries. As the artery ascends it diverges from the median line, on account of the interposition of the lateral lobe of the thyroid gland between it and the trachea, and as a result of the width of the larynx. It is covered by the skin, superficial fascia, platysma myoides muscle, superficial layer of the deep fascia, the anterior border of the sterno-mastoid mus- DISSECTION OF TIIK NECK. 75 cle, and the anterior wall of the carotid sheath ; in addition to these, at the lower part of the neck are the sterno-hyoid and sterno-thyroid muscles, the thyroid gland, which slightly overlaps it, the omo-hyoid muscle and the anterior jugular vein, which cross it. The descendens hypoglossi nerve and ansa hypoglossi also lie in front of it, and the middle sterno-mastoid artery and the superior and middle thyroid veins cross it. Behind it are the rectus capitis anticus major and tlie longus colli muscle, the pneumogastric, sympathetic, and cardiac nerves, the recurrent laryngeal nerve, at the lower part of the neck, and the inferior thyroid artery crossing behind it at the level of the cricoid cartilage. To the inner side of the artery are the trachea and esophagus, the recurrent laryngeal nerve lying between them, the lateral lobe of the thyroid gland, the terminal portion of the infei'ior thyroid arterj', the larynx, the pharynx, and the superior thyroid artery. To the outer side of the artery are the internal jugular vein and the pneumogastric nerve. The common carotid artery seldom gives off branches, but may, when the bifurcation is higher than usual, give off the .superior tln'roid artery. The bifur- cation of the artery may occur higher or lower than the upper border of the thyroid cartilage, and is not infrequently situated opposite the greater cornu of the hyoid bone. Aneurysm of the common carotid artery most frequently develojis near its bifurcation. Pressure upon the internal jugular vein by an aneurysm of the common carotid artery produces cyanosis or duskiness of the face and scalp, head- ache, and puffiness or edema of the face ; pressure upon the sympathetic cord causes dilatation of the pupil, and, later, contraction of the pu])il ; ])r(•^^sure upon the superior laryngeal nerve causes cough, and spasm or paralysis of one crico-thyroid muscle ; and pressure upon the recurrent laryngeal nerve, spasm or paralysis of the muscles of one side of the larynx, hoarseness, and difficulty in phonation. These aneurysms at the side of the neck produce a pulsating swelling which resembles that seen in enlargement of one lateral lobe of the thyroid gland. As the thyroid gland adheres to the trachea, enlargements or tumors of that organ move upward and downward with the larynx and trachea during deglutition, whereas an aneurysm of the common carotid artery remains stationary. Ligation of the common carotid artery. — In wounds or aneurysm of this artery or one of its branches, it may require a ligature. It is tied, preferably, in the superior carotid triangle, opposite the cricoid cartilage and innnediately above the point where the omo-hyoid muscle crosses its sheath. The incision is made along the anterior border of the sterno-mastoid muscle, cutting through the skin, superficial fascia, platysma myoides muscle, and superficial layer of the deep fascia ; the sterno-mastoid muscle is then displaced outward, and the sheath with the descen- dens hypoglossi nerv^e upon it exposed. As the internal jugular vein slightly 76 SURGICAL ANATOMY. overlaps the outer side of the artery, a small incision should be made in the inner side of the sheath, and the needle passed from without inward, avoiding the inter- nal jugular vein and the pneumogastric nerve. The opening in the sheath should lie small, so that the vasa vasorum and the nutrition of the vessel will not be unnecessarily disturbed. In exposing the carotid sheath, the superior or middle thyroid vein and the middle sterno-mastoid artery may be severed. In the inferior carotid triangle the artery is ligatured with more difhculty and danger, because it is deeper and covered by three layers of muscles : the sterno-thyroid, sterno-hyoid, and sterno-mastoid ; and, on the left side, the internal jugular vein turns forward in front of the artery at the root of the neck to join the subclavian vein. Intercarotid body or ganglion. — This small, oval, reddish-brown body is situated in the interval between the external and internal carotid- arteries, beliind the bifurcation of the common carotid artery. It receives filaments from the sympathetic nerve, and resembles the coccygeal body or Luschka's gland. The Pneumogastric or Vagus Nerve. — The pneumogastric nerve, the tenth and longest of the cranial nerves, has an extensive area of distribution. It supplies branches to the dura mater, external ear, pharynx, larynx, esophagus, trachea, Ijronchi, lungs, stomach, spleen, liver, and to the sympathetic system of nerves in the cervical, thoracic, and abdominal regions. It leaves the cranial cavity at the jugular foramen, inclosed within the same sheath of the dura mater as the spinal accessory nerve. It runs downward between the internal jugular vein and the internal carotid artery, passing next between the internal jugular A^ein and the common carotid artery, lying behind and between them in the posterior com- partment of their sheath. It enters the chest at its superior opening. On the right side it passes between the first portion of the subclavian artery and the subclavian vein, while on the left side it runs between the first portion of the subclavian artery and the common carotid artery, beneath the left innominate vein. Its course in the chest will be included in the description of that part of the body. The pneumogastric nerve, owing to its position between the internal jugular vein and the internal carotid artery, is closely associated with the glosso- pharyngeal, spinal accessory, and hyjio-glossal nerves. These nerves accompany the internal carotid artery but a sliort distance, the glosso-pharj'ngeal nerve curving forward between the external and internal carotid arteries, the spinal accessory nerve turning backward beneath the internal jugular vein, and the hypo-glossal nerve curving forward over the internal and external carotid arteries and the root of the occipital arterj-. There are two ganglia on the pneumogastric nerve : the ganglion of the root, and the ganglion of the trunk. The ganglion of the root is a small, rounded swelling seen upon the nerve as it lies in the jugular foramen. The ganglion of the trunk PLATE XVI. Posterior auricular n. Facial n. Transverse process of atlas External carotid a. Ascending pharyngeal a. Lingual n, Submaxillary ganglion Hyo-glossus m. Facial a. Genio-hyo-glossus m. Sublingual a. Genio-hyoid m. Left d'gastric m. Mylo-hyoid nn.(cut) Occipital a.--' Superior sterno-mastoiu a Descendens hypoglossi n Internal catotid a, Ant.div.4th cervical n Rectus capitis anticus major Middle sterno-mastoid a, Subclavian a, Subclavian v. Suprascapular a Inferior stvrno-mastoid a. InterneJ nnammary a. {under phrenic n.) Vertebral v Bifurcation of innominate a. Left sterno-mastoid m. Left sterno-hyoid and sterno-thyroid m. Inferior thyroid veins Sterno-thyroid m. Sterno-hyuid m. Sterno-rtlastoid m. DEEP STRUCTURES OF NECK-CAROTID ARTERIES 78 ■ ^0 PNEUMOGASTRIC NERVE. PLATE XVI i OSterno-mastoid in Posterior auricular n Posterior auricula' a. Princeps cervicis a Occipital a Great occipital n Occipitalis m Fcitcrlor belly digastric m.(cut) Facial n. Stylo-hyoid nn.(cut) tntornal carotid a. Ascending pharyngeal a. Stylo-pharyngous m. Glcsco-phaiyngeal n. Asconcling palatine a. Superior constrictor m. Tonsillar a. Stylo-glossus m. Facial a. Senio-hyo-glossus m. Genio-hyoid rn. Left digastric m. (anterior belly) Splenius m Trapezius nn.' Tracheio mastoid m Spinal accessory n Superior cervical synnp.gang Pneunfiogastric nr Superior laryngeal n Middle constrictor m. Stylo-hyoid ligament Internal laryngeal n. External laryngeal n. Rectus capitis anticus major m Cardiac n. Sympathetic n.- Scalenus anticus m. Ascending cervical. a 'liJdIe cervical symp, gang Aitt.div. 8th. cervical n Superior intercostal a, Subclavian a.' Suprascapular a Subclavian Sublingual a. Hyo-glossus m.(cut) Mylo-hyoid m. Dorsalis linguae a. Hypoglossal n. Lingual a. Thyro-hyoid membrane nferlor constrictor m. Thyroid cartilage Crico-thyroid m. Cricoid cartilage Recurrent laryngeal n. Thyroid axis (a.) Vertebral a. Pneumogastric n. Ant. div. I St. thoracic n Phrenic n Vertebral v. triferior thyroid vein* Internal mammary a. (under phrenic n.) SYMPATHETIC NERVE AND LARYNGEAL NERVES. 79 DISSECTION OF THE NECK. 81 is a long, fusiform enlargement, situated upon tlie nerve ahout one-half of an ineh bi'low the jugular foramen. It is closely associated witli tlie hypo-glossal nerve, Avhich winds around its outer side ; below this ganglion the vagus receives some fibers from the accessory portion of the spinal accessory nerve. Branches of the Pneumogastkic Nerve. — These may be clas.silicd as commimicating branches and branches of distribution. The communicating branches connect it with the facial, glosso-pharyngeal, spinal accessory, hypo-glossal, sympathetic, and first two eervical nerves. The branches of distribulion ■aw : in the jugular foramen, the meningeal and the auricular nerve ; in the neck, the pharyngeal, superior laryngeal, recurrent laryngeal, and cervical cardiac nerves ; in the chest, the thoracic cardiac, anterior and posterior pulmonary, and esopha- geal nerves ; in the abdomen, gastric branches. The meningeal or recurrent branch is a small twig which runs upward from the ganglion of the root, through the jugular foramen, to the dura mater near the lateral sinus. The auricular (Arnold's) nerve has its origin from the ganglion of the root of the vagus, receives a branch from the petrous ganglion of the glosso-pharyngeal nerve, and passes over the bulb of the internal jugular vein to reach an ajxiture in the outer wall of the jugular fossa. It next passes through the temporal bone near the facial canal, conmumicating with the facial nei-ve, and emerging from the bone between the mastoid process and the external auditory meatus. Turning outward, it supplies the back of the pinna and part of the external auditory canal, one of its branches communicating with the posterior auricular branch of the facial ner\'e. Irritation of this nerve by a foreign body in the external auditory meatus may induce cough, which is not relieved until the foreign body is removed. This ear cough is explained by reference of the irritation to the mucous membrane of the larynx through the auricular and superior larj'ngeal branches of the pncu- mogastric nerve. The pharyngeal branch, the chief motor nerve of the pharynx, arises from the ganglion of the trunk and receives part of the accessory portion of the spinal accessory nerve. It runs behind or in iront of the internal carotid artery to the back of the pharynx, to the upper border of the middle constrictor muscle, where it assists in forming the pharyngeal plexus. This plexus is formed by branches of the glosso-pharyngeal nerve, pneumogastric nerve, and superior cervical sympa- thetic ganglion. The pharyngeal muscles and mucous membrane and the azygos uvulffi and levator palati muscles are supplied by filaments from this plexus. Tlic superior laryngeal nerve is the sensory nerve of the larynx. It arises from the ganglion of the trunk of the pneumogastric ner\'e, curving down- ward and forward behind the internal and external carotid arteries, and dividing 82 SURGICAL ANATOMY. into the external and internal laryngeal branches. The internal branch, together with the superior laryngeal artery, enters the larynx througli the thyro-hyoid membrane, supplying the laryngeal mucous membrane and the arytenoid muscle, and communicating with the recurrent laryngeal nerve. Irritation of this branch, as by a crumb of bread or a drop of water entering the larynx, causes a momentary cessation of respiration, cough, and expulsion of the intruding sub- stance. The external branch, which is smaller than the internal, descends along the side of the pharjaix under the sterno-thyroid muscle ; it supplies the crico- thyroid muscle and crico-thyroid membrane, the inferior constrictor muscle of the pharynx, and the thyroid gland ; it also sends filaments to the pharyngeal plexus, and gives oS, behind the common carotid artery, a branch to the superior cardiac nerve of the sympathetic. Paralysis of the superior laryngeal nerve may be due to pressure of an aneurysm of the external or the internal carotid artery, or to enlarged lymphatic glands or tumors. The external laryngeal division may also be compressed by aneurysm of the upper part of the common carotid artery. Anesthesia of the laryngeal mucous membrane would permit foreign bodies to enter the larynx, and cause inflammation or obstruction. The vocal cords can not be stretched, owing to paralysis of the crico-thyroid muscle, ahd the voice is, in consequence, hoarse and of low pitch. Irritation of the superior laryngeal nerve, as by aneurysm of the internal or external carotid artery, or by an enlarged thyroid gland or lymphatic glands, causes peculiar, ringing cough, without expectoration. The recurrent or inferior laryngeal nerves are the motor nerves of the larynx, supplying all of the intrinsic muscles of that organ except the crico-thyroid muscles, these being supplied by the external laryngeal branches of the superior laryngeal nerves. The right recurrent laryngeal nerve is shorter than the left, arising from the pneumogastric nerve as it crosses the first portion of the right subclavian artery. It then winds behind the first portion of the right subclavian artery, ascending obliquely inward in front of the apex of the right pleural sac, and l)ehind the root of the right common carotid artery and the terminal portion of the inferior thyroid artery to reach the groove between the trachea and esophagus. While in this groove it jjasses behind and internal to the right lateral lobe of the thyroid body, and leaves the groove to reach the intrinsic muscles of the larynx by passing behind the inferior cornu of the thyroid cartilage. Pressure upon this nerve may be caused by aneurysm of the first portion of the riglit .suliclavi;iii ai'tcry or lowcniiost portion of tlie right common carotid artery, by enhu'gement of the thyroid body, cicatrices of the apex of the right pleura, as in phthisis, or by malignant disease of the esophagus. DISSECTION OF THE NECK. 83 The left recurrent laryngeal nerve arises from the pneumogastric nerve in front of the transverse portimi nf the arch of the aorta, ami winds behind that portion of the arch helow and to the left side of the obliterated ductus arteriosus. It next ascends behind the root of the left common carotid artery to the groove between the trachea and esophagus, continuing upward to the larynx, and passing behind and internal to the left lateral lobe of the thyroid body, in a course similar to that of the right recurrent laryngeal nerve. Both nerves communicate with the superior laryngeal nerve of the same side, and with the sympathetic nerve. Pressure upon the left recurrent laryngeal nerve may be produced by aneurysm of the arch of the aorta or of the lowermost portion of the left common carotid artery, by tumors of the posterior mediastinum, by enlargement of the thyroid body, or ]>y malignant disease of the esophagus. Moderate pressure causes spasm of the muscles of the same side of the larynx, dyspnea, and change of voice. Greater pressure causes paralysis and alteration of the voice. Both nerves may be involved in labio-glosso-pharyngeal paralysis or disseminated sclerosis of the pons, medulla oblongata, and spinal cord, or by pressure from an enlarged thyroid body, or carcinoma of the esophagus. When both nerves are paralyzed the vocal cords are immovable, phonation is imperfect, and the rima glottidis is in the relaxed attitude assumed in quiet breathing. The cervical cardiac branches of the pneumogastric nerve are given off in the upper and lower part of the neck. The superior cervical cardiac branches join the cardiac branches of the .sympathetic and terminate in the deep cardiac plexus. The left inferior cervical cardiac branch passes between the pleura and the left side of the transverse portion of the aortic arch, entering the superficial cardiac plexus ■with the left superior cervical cardiac branch of the sympathetic nerve. The right inferior cervical cardiac branch passes on the trachea to the deep cardiac plexus. The thoracic and abdominal branches of the pneumogastric nerve are described with the thorax and abdomen. The Sympathetic. — The sympathetic nervous system consists of a series of ganglia, one ganglion being joined to another by connecting nerve cords ; it is also composed of gangliated plexuses, visceral ganglia, and many nerve fibers. Some of the ganglia — as, for instance, the cardiac ganglia — possess automatic action. The nerve fibers of the sympathetic system are chiefly non-medullated. The cervical portion of the sympathetic nerve is situated behind the carotid sheath or in its posterior wall, and lies beneath the prevertebral fascia, where it rests upon the rectus capitis anticus major and the longus colli mu.sclc. Three cervical ganglia — the superior, middle, and inferior — lie in each side of the neck. 84 SURGICAL ANATOMY. The superior cervical ganglion, the largest of the three, is a long, fusiform body situated opposite the transverse processes of the second and third cervical vertebrae, behind the sheath of the great vessels. It is formed probably by the fusion of four ganglia, as it communicates with four spinal nerves. It gives off an ascending and a descending branch, branches to cranial and cervical nerves, branches which follow the external carotid artery and its branches, pharyngeal branches, laryngeal branches, and the superior cardiac nerve. The ascending branch passes upward through the carotid canal, with the inter- nal carotid artery. It divides into an external and an internal branch. Its exter- nal branch forms the carotid plexus, while its internal branch forms the cavernous plexus. The descending branch passes downward to the middle cervical ganglion. The branches to the cranial nerves communicate with the ganglia of the root and trunk of the pneumogastric nerve, the petrous ganglion of the glosso-pharyn- geal nerve, and the hypo-glossal nerve. No branches pass to the spinal accessory nerve. The branches to the spinal nerves pass outward over the rectus capitis anticus major muscle to join the upper four cervical nerves. The branches which ramify upon the external carotid artery and its branches (nervi mollcs) proceed from the upper part of the ganglion. The nervi molles upon the external carotid artery supply branches to the intercarotid body ; the nervi molles of the facial artery, branches to the submaxillary ganglion (the sym- pathetic root) ; those upon the middle meningeal artery, the sympathetic root to the otic ganglion, and the external superficial petrosal nerve, which is the sj'm- pathetic root of the geniculate ganglion of the facial nerve. The pharyngeal branches pass inward behind the internal and external carotid arteries, and assists in forming the pharyngeal plexus. The laryngeal branches join the superior laryngeal nerve. The superior cervical sympathetic cardiac nerve arises from the lower part of the superior cervical sympathetic ganglion, or from the cord which runs to the middle cervical ganglion. It runs downward behind the carotid sheath, communicating with the superior cardiac branch of the pneumogastric, the external laryngeal, and the recurrent laryngeal nerve. In the chest the two nerves take different courses. The right superior cervical sympathetic cardiac nerve passes in front of or behind the first portion of the subclavian artery, following the innominate artery, and terminating in the deep cardiac plexus. On the left side the nerve passes between the left common carotid and the left subclavian artery, and over the left side of the arch of the aorta, to the left of the left pneumogastric nerve, terminat- ing in the superficial cardiac plexus. The middle cervical or thyroid ganglion, the smallest of the three ganglia. DISSECTION OF THE NECK. 85 appears as a swelling upon the sympathetic cord. It may, however, be absent. It rests upon or beneath the inferior thyroid artery, opposite the transverse process of the sixth cervical vertebra, and is formed probably by tlie fu.sion of two ganglia, as it couununicates with two spinal nerves. It gives off conmiunicating branches to the superior and inferior cervical ganglia, and to the fifth and sixth cervical nerves, thyroid branches, and tlie middle cardiac nerve. The communicating branch to the superior ganglion is the cord of the sympa- thetic nerve. The commnnicaiing branches to the inferior ganglion arc the main sympathetic cord, which passes behind the first portion of the subclavian arterj', and one or two nerves which form a loop (ansa Vieussenii) in front of and below the artery. The thyroid branches accompany the inferior thyroid artery to the thyroid body. The middle cardiac nerve, the largest of the three cervical sympathetic cardiac nerves, arises from the middle ganglion or the sympathetic cord just below it. It communicates with the .superior cardiac and the recurrent laryngeal nerve, and passes in front of or behind the first portion of the subclavian artery, entering the 'deep cardiac plexus. The inferior cervical ganglion is intermediate in size between the middle and superior ganglia. It is deeply situated between the transverse process of the seventh cervical vertebra and the neck of the first rib, and lies to the inner side of the superior intercostal artery, behind the vertebral artery. It is formed prob- ably by the fusion of two ganglia, as it communicates witli two spinal nerves, the seventh and eighth cervical. It is joined to the first thoracic ganglion by two large nerves, and may be fused with that ganglion. The sympathetic cord and the ansa Vieussenii connect it with the middle cervical ganglion. It gives off the inferior cardiac nerve and branches which form a plexus on the vertebral artery. The inferior cervical sympathetic cardiac nerve arises from the inferior cervical ganglion, or occasionally from the first thoracic ganglion. It passes behind the .subclavian arterj-, communicating with tlie recurrent laryngeal and the middle cardiac nerve, and descending upon the trachea to enter the deep cardiac plexus. The branches forming a plexus {vertebral plexvf:) upon the vertebral artery accompany that vessel into the cranial cavity, after which they follow the basilar and cerebral arteries. It is through this plexus of nerves that contraction of the pupil of the same side results after ligation of the vertebral artery. The External Carotid Artery, so called because it sujiplies the tissues on the outside of the cranium, is the smaller of the two terminal divisions of the common carotid artery. It arises opposite the upper border of the thyroid cartilage, 86 SURGICAL ANATOMY. ascends, and enters the parotid gland, where it lies beneath the temporo-maxillary vein and facial nerve. Opposite the neck of the lower jaw it divides into its two terminal branches, the temporal and internal maxillary arteries. At first it lies to the inner side of the internal carotid artery, but later becomes superficial to that vessel. Relations. — It is covered by the skin, superficial fascia, platysma myoides muscle, superficial layer of the deep cervical fascia, anterior border of the sterno- mastoid muscle, and a portion of the parotid gland, the temporo-maxillary vein, and the facial nerve. It is crossed by the hypo-glossal nerve, the facial and lingual veins, the posterior belly of the digastric muscle and the stylo-hyoid muscle, and enters the parotid gland. Along the inner side of the vessel, from below upward, are the wall of the pharynx, the hyoid bone, the ramus of the lower jaw, and the stylo-maxillary ligament, from which it is separated by a portion of the parotid gland. Beneath it, near its origin, is the superior laryngeal nerve ; higher in the neck the stylo-glossus and stylo-pharyngeus muscles, the stylo-hyoid ligament, the glosso-pharyngeal nerve, the pharyngeal branch of the pneumogastric nerve, and part of the parotid gland separate it from the internal carotid artery. On its outer side, at its origin, is the internal carotid artery. The external carotid artery differs from most of the arteries in not having a companion vein, but a vein formed by the union of the temporal and internal maxillary veins does occasionally accom- pany it. A line line drawn from the junction of the sternum with the clavicle, to a point midway between the angle of the lower jaw and the mastoid process repre- sents the course of the common and external carotid arteries. Branches of the External Carotid Artery. — These are the superior thyroid, lingual, facial, occipital, posterior auricular, ascending pharjmgeal, superficial temporal, and internal maxillary arteries. They may be divided into four sets : an anterior, a posterior, an ascending, and a terminal. The anterior set comprises the superior thyroid, lingual, and facial ; the posterior, the occipital, and posterior auricular ; the ascending, the ascending pharyngeal ; and the terminal, the superficial temporal, and internal maxillary. The superior thyroid artery, the first branch given off" from the external carotid, arises just below the greater cornu of the hyoid bone. Throughout the greater part of its course it occupies the superior carotid triangle. It passes forward and then downward and inward behind the omo-hyoid, stern o-thyroid, and sterno-hyoid muscles to the upper and front part of the thyroid body, in which it terminates. Its branches are the hyoid, middle sterno-mastoid, superior laryngeal, and crico-thyroid arteries. The hyoid (infra-hyoid) artery is very small. It runs inward along the lower PLATE Anterior Cerebral Middle Cerebra L , Posterior Cerebral — ., Anterior Cerebellar - - Internal Carotid ■ Anterior communicating J\)slCommimicallmf'- ^^ Sup Cerebellar Occipital- - Prin.Cervicis Tliyroidea ima Left Common Carotid -Left Subclavian Transversa I IS colli 'Suprascapular 'Aorlu^ DIAGRAM OF SUBCLAVIAN AND CAROTID ARTERIES AND THEIR BRANCHES 87 PLATE XIX, Supraorbital Frontal veins Transverse facial v Orbitnl V Middle temporal v, / Superficial temporal v. ^Communication v/ith mastoid \ Occipital V. Angular v VEINS OF SCALP, FACE, AND NECK. 89 DISSECTION OF THE KECK. !)1 border of the hyoid bone, beneath tlie tliyro-hyoid muscle, supplyinj^ tlic infni- liYoid bursa and the thyro-hyoid muscle, and communicates witli tlir iulVa-liyoHl artery of the opposite side and with the supra-hyoid branch of the lingual artery. The middle stcrno-madnid artery j)asses downward and outward over the sheath of the common carotid artery in the superior carotid triangle, the triangle of election ; it is chiefly distributed to the middle itortion of the sterno-mastoid muscle, supplying also tlie thyro-hyoid, Kterno-thyroid, stcrno-hyoid, cuiin-liydid, and platysma myoides muscles, and tlie overlying skin. The autlior has observed cases in which this vessel was unusually large, running into the occipital triangle, and giving rise to fatal hemorrhage following the opening of an abscess. The superior laryngeal arterij, larger than either of the two preceding branches, is accompanied by the internal branch of the superior laryngeal nerve ; it passes beneath the thyro-hyoid muscle and pierces the thyro-hyoid meml)rane, supj)lying the muscles and mucous membrane of the larynx, and anastomosing with tiie superior laryngeal artery of the opposite side and the inferior laryngeal branch of the inferior thyroid artery. At times it enters the larynx through a foramen in the thyroid cartilage. The crico-thyroid artery runs across the crico-thyroid membrane, just below the lower border of the tiiyroid cartilage, and is continuous with the crico-thyi'oid artery of the opposite side. A small branch usually passes through the crico- thyroid membrane to the interior of the larynx. The operation of laryngotomy is performed by carrying a transverse incision through the crico-thyroid mcnd)ranc, close to the cricoid cartilage, and it is therefore important to keep in miml the relation which the crico-thyroid artery bears to the membrane, and the necessity, when time is at command, for exposing the membrane by careful dissection. The superior thyroid vein, the accompanying vessel of the superior thyroid artery, crosses the terminal part of the common carotid artery, and empties into the internal jugular vein ; it may, at times, enter the facial or lingual vein. It emerges from the upper part of the lateral lobe of the thyroid Itody, accompany- ing the superior thyroid artery for a .short distance, and then crossing the coinnioii carotid artery to empty into the internal jugular vein. A branch of the vein, or one which arises separately in the thyroid body, usually passes upward and anterior to the common carotid and the external carotid artery, and empties into the lin- gual vein. The lingual artery, the second branch of the external carotid, arises opposite the greater cornu of the hyoid bone between the superior thyroid and facial arte- ries, occasionally arising as a common trunk with the latter. It consists of three portions : the first or oblique, which lies between its origin and the outer border of the hyo-glossus muscle ; the second or horizontal jiortion, beneath the hyo-glossus 92 SURGICAL ANATOMY. muscle and parallel with the greater cornu of the hyoid bone; and the tJiird or ascending portion, between the hyo-glossus and the genio-hyo-glossus muscle. The first or oblique portion lies in the superior carotid triangle, and runs upward and inward to the upper border of the greater cornu of the hyoid bone, resting upon the middle constrictor muscle of the pharynx and the internal laryngeal branch of the superior laryngeal nerve. Thence it passes beneath the hj'o-glossus, the pos- terior belly of the digastric, and the stylo-hyoid muscle, emerging from the superior carotid triangle and entering the submaxillary triangle. This portion of the vessel is crossed by the hypo-glossal nerve and lingual vein, and gives off the supra-hyoid branch. The second or horizontal portion runs beneath the hyo- glossus muscle. (See description of submaxillary triangle.) The third or ascend- ing portion runs beneath the anterior border of the hyo-glossus on the outer aspect of the genio-hyo-glossus muscle, and runs forward to the tip of the tongue, terminating as the ranine artery; the terminal portion of the lingual artery is separated from the cavity of the mouth by the mucous membrane which lines it. (See description of 'submaxillary triangle.) The lingual vein is seen crossing the first portion of the lingual artery with the hypo-glossal nerve. It runs over the external carotid arterj^ and opposite the greater cornu of the hyoid bone empties into the internal jugular vein sejmrately, or by a common trunk with the facial vein and a brancli of the siiperior thyroid vein. These veins and their common trunk may cau.se some difficulty in ligation of the common carotid or first portion of the lingual artery. The facial artery (external maxillarj') arises from the external carotid above the lingual artery, passes upward beneath the posterior belly of the digastric and the stylo-hyoid muscle and the submaxillary gland, being embedded in a groove on the under surface of the latter ; it then cur\'es upward over the body of the lower jaw, reaching the face at the anterior inferior angle of the masseter muscle, where the artery can be compressed and its pulsations readily felt. It consists of two portions, a cervical and a facial. Tlie Branches given off from the ceiTical portion of the facial artery are the ascending or inferior palatine, the tonsillar, the submaxillary, the submental, and the muscular. The ascending or inferior palatine artery occasionally arises separatel}^ from the external carotid artery. It ascends between the internal and external carotid arteries, then runs between the stylo-glossus and stylo-pharyngeus muscles, and finally between the internal pterygoid muscle and the superior constrictor muscle of the pharynx. Reaching the levator palati muscle, it divides into two branches : one, the palatine, follows the course of the levator palati mu.scle to supply the soft palate, and anastomoses with the ascending palatine artery of the opposite side, the ! DISSECTION OF THE NECK. 93 descending palatine brancli of Uie internal niaxiilaiy artery, and the aseendiug pharvn^val artery; the dther hranch, the tonsillar, perforates the supfrior eon- strietormuscle of the pharynx, and snpplies the tonsil and the Eustaehiaii tube, anastomoses with the tonsillar branehes of the ascending pharyngeal and facial arteries, and with the descending or posterior palatine branch of the internal max- illary artery. The (oiisilliir artcrii, smaller than the ascending palatine artery, passes up- ward between the internal pterygoid and the stylo-glossus muscle. It perforates the superior constrictor muscle of the ])harynx ojiposite thr tonsil, ami supplies branches to the tonsil and root of the tongue. It anastomo.scs with the tonsillar branch of the ascending palatine and the other tonsillar arteries. The glandular (submaxillary) branches, three or four in number, supjtly the submaxillary gland, and are derived from the portion of the artery in contact with the gland ; some twigs usually run to Whai'ton's duct. The submental artery is the largest of the branches given off from the cervical portion of the facial artery. It arises from this vessel, beneath the sub- maxillary gland. It next runs forward upon the mylo-hyoid muscle, under the lower border of the lower jaw, and beneath the anterior belly of the digastric muscle, to the symphysis of the lower jaw, where it ilivides into a superficial and a deep branch. The superficial branch winds over the lower jaw and runs in the superficial fascia of the chin, anastomosing with the inferior labial artery. The deep branch runs beneath the depres.sor labii inferioris muscle, and anasto- moses with the inferior labial and mental arteries. Its branches. are muscular, which supply the adjacent muscles ; perforating, which pierce the mylo-hj'oid muscle to anastomose with the sublingual artery ; and cutaneous, to the overlying skin. The muscular branches supply the posterior belly of the digastric, the stylo- hyoid, the stylo-glossus, the mylo-hyoid, and the internal pterygoid muscle. The facial vein leaves the face at the anterior inferior angle of the masseter muscle. It passes over the submaxillary gland, the stylo-hyoid and posterior belly of the digastric muscle, which separate it from the Axcial artery. It receives the anterior division of the temporo-maxillary vein, crosses the external carotid artery, and empties into the internal jugular vein opposite the greater cornu of the hyoid bone. It may be injured in opening abscesses situated where it passes over the svibmaxillary gland. The occipital artery, quite a large vessel, is one of the posterior branches of the external carotid artery. It arises opposite the facial artery, near the lower border of the posterior belly of the digastric muscle, along which it runs to the interval between the mastoid process of the temporal bono and the transverse 94 SURGICAL ANATOMY. process of the atlas, to reach the groove on the under surface of the mastoid portion of the temporal bone. At its origin it is crossed by the hypo-glossal nerve. On its way to the mastoid process it crosses the internal carotid artery, the internal jugu- lar vein, the i^neumogastric, hypo-glossal, and spinal accessory nerves, and passes beneath the lower portion of the parotid gland. It runs horizontally backward through the occipital groove of the temporal bone, covered by all the muscles attached to the mastoid process, — the sterno-mastoid, splenius capitis, trachelo- mastoid, and posterior belly of the digastric muscle, — and lies upon the superior oblique and complexus muscles. Reaching the back of the head, the artery pierces the trapezius muscle close to the superior curved line of the occipital bone, ascends, and divides into branches, as described under the Dissection of the Scalp. As it pierces the trapezius muscle and ramifies in the superficial fascia of the scalp, it is accompanied by the great occipital nerve. This vessel is conveniently divided by the sterno-mastoid muscle into three parts, — a first, a second, and a third portion, — situated respectively internal to, beneath, and external to that muscle. The first portion is covered only by skin and fasciae, except where it is overlapi^ed by the posterior belly of the digastric muscle, the parotid gland, and the temporo-maxillary vein. It is crossed by the hypo-glossal nerve. Behind it successively lie the internal carotid artery, the hypo-glossal and the pneumo- gastric nerve, the internal jugular vein, and the spinal accessory nerve. The first portion of the artery is the 2}t(t<^c of election for ligation. An incision is car- ried along the anterior border of the upper part of the sterno-mastoid muscle while the neck is well extended. The skin, superficial fascia, platysma mj'oides muscle, and the superficial layer of the deep fascia are divided, and the artery is seen run- ning parallel with or beneath the lower border of the digastric muscle. The hypo- glossal nerve will be seen curving around the artery at its origin. The second por- tion dips deeply under the digastric muscle between the mastoid process of the temporal bone and the transverse process of the atlas, being covered, as previously stated, by the muscles attached to the mastoid process, and Ijang successively against the rectus capitis lateralis, which separates it from the vertebral artery, the mastoid portion of the temporal bone while piassing through the occipital groove, and finally against the insertion of the superior oblique muscle. The third portion emerges from beneath the posterior border of the sterno-mastoid and splenius muscles, lying upon the complexus in the triangular interval between the sterno-mastoid and the trapezius, and piercing the trapezius muscle about midway between the mastoid process and the external occipital protulierancc, to become subcutaneous and pass ujiwnrd in the superficial fascia of the scalp. It is accompanied by the great occipital nerve. The Branchks given off from the occipital artery are flic nniscular, superior DISSECTION OF THE NECK. 95 sterno-mastoid, auricular, posterior meningeal, mastoid, princeps cervicis, coiunumi- cating, and terminal. The muscular branches supply the digastric, stylo-hyoid, splenius, trachclo- mastoid, trapezius, recti, superior and inferior oblique, and the occipitalis muscles. The superior sterno-mastoid artery enters the sterno-mastoid muscle %vith the spinal accessory nerve. It arises from the first portion of the occipital artery, and passes downward and backward over the hypo-glossal nerve to enter the sterno- mastoid muscle. The auricular branch supplies the back of the pinna. At times it is large and takes the place of the posterior auricular arterj'' ; it may send a branch to the dura mater through the mastoid foramen. The posterior meningeal branches ascend along the internal jugular vein, and enter the cranial cavity through the jugular foramen to supply the dura mater of the posterior cranial fossa. The mastoid branch is a small vessel which traverses the mastoid foramen to supply the diploe, the walls of the lateral sinus, the dura mater, and the mas- toid air cells. The princeps cervicis artery is the largest branch of the occipital artery. It nnis down the back of the neck between the splenius and the complexus muscle, and divides into a superficial and a deep branch. The superficial branch pierces the splenius and runs between it and the trapezius, supplying these muscles and anastomosing with the superficial cer\'ical artery, one of the terminal branches of the transversalis colli ; the deep branch descends between the complexus and semi- spinalis colli, supplies these muscles, and anastomoses with branches of the verte- bral and with the deep cervical branch of the superior intercostal artery. The anastomoses between the occipital, vertebral, and superior intercostal arteries play an important part in the formation of the collateral circulation after ligation of the common carotid or the subclavian artery. Communicating branches ran between the recti and the superior and inferior oblique muscles to anastomose with branches of the vertebral artery. The terminal branches pass laterally and mesially upward in the superficial fascia of the occipital region of the scalp to supply the scalp and pericranium, and are known as external and internal. They anastomose M-ith the occipital artery of the opposite side, the posterior auricular and the superficial temporal artery. The occipital vein accompanies the third portion of the occipital artery ; it communicates with the lateral sinus tln-ough the mastoid foramen, and with the diploic veins, piercing the trapezius muscle with the occipital arterj'. It enters the occipital triangle and terminates in the deep cervical vein, or it may bifiircate, one subdivision emptying into the posterior jugular vein, and the other 96 SURGICAL ANATOMY. into the deep cervical vein. The deep cervical vein accompanies the deep branch of the princeps cervicis artery, then the profunda cervicis, passes between the trans- verse process of the seventh cervical vertebra and the neck of the first rib, and empties into the innominate or vertebral vein. The posterior auricular artery, the remaining posterior branch of the external carotid, is smaller than the occipital artery, and arises just above the pos- terior belly of the digastric muscle. It ascends obliquely upward and backward in the parotid gland, to the furrow between the pinna of the ear and the mastoid process of the temporal bone, passing below the facial nerve and over the spinal accessory nerve. Immediately above the mastoid process it divides into two branches — an anterior, which passes forward and anastomoses with the posterior division of the temporal arterj^ and a posterior, which anastomoses with the occi- pital artery. The Branches of the posterior auricular artery are the parotid, muscular, stylo-mastoid, auricular, and mastoid. The parotid branches supply the lower end of the parotid gland, anastomos- ing with other arteries distributed to the gland. ' The muscular branches supply the digastric, stylo-hyoid, sterno-mastoid, and retrahens aurem muscles. The stijlo-rnastoid branch enters the stylo-mastoid foramen of the temporal bone, and supplies the tympanum, the mastoid cells, and the semicircular canals. In the fetus a branch of the stylo-mastoid artery forms, with the tympanic branch from the internal maxillary artery, a vascular circle around the circumference of the tympanic membrane ; from this circle smaller vessels are given off, which ramify upon the membrane. From the acjueduct of Fallopius it sends branches to the external auditory meatus {meatal) ; to the mastoid cells and mastoid antrum (mastoid) ; to the staj^edius muscle (stapedic) ; to the tympanum, forming the anas- tomotic circle in the fetus {tympanic) ; to the vestibule and semicircular canals (vestibular); and a final twig (fermiTirr/), which accompanies the great superficial petrosal nerve through the hiatus Fallopii and anastomoses with the petrosal branch of the middle meningeal arteiy. The auricular branch (anterior terminal) supplies the back part of the auricle, and anastomoses with the posterior temporal and auricular branch of the superficial temporal artery ; some of its branches perforate the cartilage of the pinna to supply its anterior surface. Tlie mastoid branch, (occipital branch) crosses the insertion of the sterno- mastoid muscle, supplies the structures over the mastoid process, and anastomoses with the occipital artery. The posterior auricular vein, wliich is of considerable size, accompanies the DISSECTIOX OF Till': .\KVk'. 97 terminal pDrtioii of tlic posteiior auricular artery and juius the posterior liivisinn oi" the temporo-niaxillaiy vein to form the external jugular vein. The posterior auricular nerve. — liunniiii;- close to the posterior aurieular artery is tiie posterior aurieular nervi', the first branch given off from the facial after its exit from the stylo-mastoid foramen. It ascends in front of the mastoid process, where it communicates with the great auricular nerve and the aurieular branch of the pneumogastric nerve. Between tlie mastoid process and tlic external auditory meatus it divides into two branches : an anterior, which supplit's tlie retrahens aurena and the small muscles on the back of the pinna,, and a. posterior occipital, the larger, which passes along the superior curvdl line of the occijutal bone, supplying the occipitalis muscle and communicating with the small oceijiital nerve. The ascending pharyngeal artery, a long, slender brandi, the smallest given otf from the external carotid arterj', arises from the back part of tliat artery, about one-half of an inch above the bifurcation of the common carotid artery. At times, liowever, it arises from the common carotid artery. It is situated deep in the neck, in relation with tlie internal carotid artery, and lies upon the rectus capitis anticus major muscle. It ascends between the internal carotid artery and the side of the pharynx, and beneath the stylo-pharyngeus muscle and the glosso-pharyngeal nerve, to the base of the skull : here it enters the pharynx al)ove the superior constrictor muscle, to end in the soft palate. It gives off prevertebral, pharyngeal, meningeal, palatine, and tympanic branches. The prevertebral branches are small vessels which pass outward to supply the rectus capitis anticus major and minor muscles, the sympathetic, pneumogastric, and hypo-glossal nerves, and the deep cervical chain of lymphatic glands. They anastomose with the ascending cervical artery. The pharyngeal branches, three or four in number, supply the upper and middle constrictor muscles, the mucous membrane of the pharynx, and the stylo- pharyngeus muscle. The largest of these branches, the palatine, enters the pharynx above the superior constrictor muscle, and terminates in the soft palate, the Eustachian tube, and the ton.sil ; it takes the place of the ascendijig palatine branch of the facial artery when this vessel is small. The meningeal branches, three in immber, enter the cranial cavity through the jugular foramen, in company with the internal jugular vein, through tiie anterior condyloid and middle lacerated foramina, to supply the dura mater. The tympanic branch traverses the tympanic canaliculus, together with the tympanic branch of the glosso-pharyngeal nerve, enters the tympanum, anasto- moses with the other tympanic arteries, and supplies the adjacent structures. The descending pharyngeal vein arises in a minute plexus at the back part S— II-7 98 SURGICAL ANATOMY. and side of the pharynx. After receiving meningeal l>ranches, the veins from the soft palate and Eustachian tube, and the Vidian vein, it terminates in the in- ternal jugular vein. It occasionally em[)ties into the facial vein. Internal maxillary and temporal arteries. — The description of the internal maxillary arter}- is given under the Dissection of the Pterygo-maxillary Region. The temporal artery is described under the Dissection of the Face. The Submaxillary Triangle (continued). — The digastric muscle consists of two muscular bellies, an anterior and a posterior, united by an intervening tendon. The posterior belly, the larger of the two, arises from the digastric groove, which lies to the inner side of the base of the mastoid process of the temporal bone ; the anterior belly, the shorter of the two, arises from the depression on the deep surface of the lower jaw at the side of the symphysis. The fibers of the posterior belly are directed downward, forward, and inward ; those of the anterior, downward and backward to the intervening tendon, which pierces the stylo-hyoid muscle, and is connected to the side of the bodj^ of the hyoid bone by a jirocess of the deep cervical fascia lined with a synovial mem- brane. A broad aponeurotic expansion — the supra-hyoid aponeurosis — is given off on each side from the tendon of the digastric muscle, and is attached to the body and greater cornu of the hj'oid bone and to aponeurotic expansion of the opposite side, so that the interval between the anterior bellies of the digastric muscles is occupied by this expansion. The posterior belly passes over the sheath of the carotid vessels, the hypo-glossal and spinal accessory nerves, and beneath the sterno-mastoid and trachelo-mastoid muscles. The occipital artery passes upward and backward along the lower border of the posterior belly. The anterior belly may be absent and the posterior belly may be double. At times accessory slips join the posterior belly from the styloid pi'ocess or pharynx. Nerve Supply. — The posterior bell}' of the digastric muscle is supplied by a branch from the facial nerve ; the anterior belly, by the mylo-hyoid, a branch of the inferior dental nerve. Br,ooD Supi'LY. — From muscular branches of the facial, occipital, and poste- rior auricular arteries. Action. — It depresses the lower jaw and assists in opening tin- nmutli. If tlic ](i\ver jaw b(^ fixed, the (wo bellies acting together wnuld raise (he liyurfai'c df the styloid process of the temporal bone, whence it passes downwanl and forw^ird to be inserted into the outer surface of the hyoid bone where the greater eornu joins the body. It lies above the posterior belly of the digastric muscle, and is pierced near its insertion hy tlie tt'udon of the digasti-ic. In some cadavers the stylo-hyoid muscle is absent. Nerve Supply. — From the facial nerve. Blood Supply. — From the nuiscular twigs of the facial, occipital, and ]io.ste- rior auricular arteries. Action. — It raises and draws tiic hyoid bone backward, thus preventing the rrturn of ludd into the pliarynx during deglutition. The submaxillary gland, one of the three salivary glands, is situated in the submaxillary triangle and extends upward under the body of the lower jaw as far as the attachment of the mylo-hyoid muscle. It weighs about two (h-ams. It consists of a larger superficial portion and a smaller deep portion. The superficial portion of the gland is covered by the skin, superficial fascia, platysma myoides muscle, infra-maxillary branches of the facial nerve, superficial layer of the deep fascia, facial vein, some lymphatic glands, and the boon the hyo-glo.s.sus muscle, and beneath the submaxillary gland. Here it forms the base of the lingual triangle, and lies above the lingual vein. It supplies all of the extrinsic muscles of the tongue, the thyro-hyoid, and through the descendens hypoglossi nerve assists in supplying tlie onio-hyoid, sterno-hyoid, and sterno-thyroid muscles. The branch to tlie thyro-hyoid muscle is given off near the tip of the greater cornu of the hyoid bone, and passes obli(jUcly down- ward and forward to reach the superficial surface of that muscle. Paralysis of one Jiypo-fjlossal nerve causes wasting and flabbiness of the corre- sponding half of the tongue ; when the tongue is protruded, the tip of the organ is carried townnl the paralyzed side. Dissection. — In <'(iin|ili'liiig llie ilisscctidu i)f llie submaxillai'v triangle, the anterior belly of tlie digastric uuiscle slmulil be detached from llie knwr jaw and dis]ilaccd downward, wluii the inylii-liyoiil, the muscle forming the greater jiart PLATE XXII Posterior hr. of descend incj palatine A Pal aline hr. of ascending pharyngeal A Ascending pharyngeal A. Ascending palalinc hr •^ 'of facial A Tonsillar br. — of facial A. Stylo- pharyngeus M- Facial A. Middle conslriclorM .- Dors alls linguae A. Lingual A. External carol id A. ^ Superior Ihyroid >.. v.^,^ I r- — Infra - by aid br. of sup. tfiyroLclA^j)L(jc,f[jcM. ^nnrn -h\rni ri hr ca..t^ L,,^,"j \A -Descending palatine A. "Anterior br. of descending palatine A . ,St}-lo-gluss//.vAl. ^Palato -glossusM. ^Tonsillar br dorsalis linguae A . Ranine A Supra- hyoid br of ' Ungual A. Stylo-hyoid M. Sublingual A Artery of fraenum -Submental A. (Jcrnn-hyoid ?!. Cenio fi\-o -glossus M. ARTERIES OF TONGUE AND TONSIL 105 DISSECTION OF THE NECK. 107 of tlio floor of the triangle, as well as the greater part of the floor of the niuuth, will 1)0 completely exposed. Tile mylo-hyoid is a triangularly sliaped muscle, with its base at the lower jaw anil its apex at the hyoitl bone ; it unites along the middle line with tlie mylo- hyoid muscle of the opposite side. It is sometimes termed the diaphragm of the muuth, or the vijuier diaphi'agni. It arises from the mylo-hyoiil ridge (inti'rnal oblicjue line) of the lower jaw, its origin extending fnun the symphysis as far backward as the last molar tooth. The posterior fibers are inserted into the body of the hyoid bone ; the middle and anterior fibers into the median fibrous raphe, where they join the fibers of the opposite muscle. Its lower or cutaneous surface has the anterior belly of the digastric muscle, the supra-hyoid aponeurosis, the mvlo-hyoid nerve and artery, the submental vessels, and the .submaxillary glands in relation with it. The duct of the submaxillary gland winds around its free posterior border. In relation with its deep or buccal surface are the genio-hyoid muscle, part of the hyo-glossus and stylo-glossus muscles, the deep pai't of the submaxillary gland, Wharton's duct, the hypo-glossal and gustatory nerves, the submaxillary ganglion, the sublingual gland, the ranine and sublingual arteries, and the mucous membrane of the mouth. Nerve Supply. — From the mylo-hyoid branch of the inferior dental nerve. Blood Supply. From the submental branch of the facial artery. Action. — When both muscles act conjointly from their point of origin they elevate the hyoid bone, the larynx, and the floor of the mouth, preparatory to swallowing ; when acting from their hyoid attachment they assist in depressing the jaw and in opening the mouth. Dissection. — Divide the facial vessels immediately below the lower jaw, and displace them upward with the superficial jrart of the submaxillary gland, leaving in situ the deep part of the gland which turns beneath the mylo-hyoid muscle and has the submaxillary ganglion in contact with it. Divide the small vessels and nerves on the cutaneous surface of the mylo-hyoid mnscle, detaching it from the lower jaw and the niylo-liy(iio-glossal nerve. Blood Supply. — From the lingual artery. 108 SURGICAL ANATOMY. Action. — It raises ami advances tlie. liyoid bone ; when the mouth is closed, acting in the reverse direction, it assists in depressing the lower jaw and in opening the mouth. It may be inseparable from the genio-hj'oid muscle of the other side. Dissection. — The lower jaw should be sawed through at two points — viz., immediately in advance of the angle and at the symphysis ; the intervening por- tion, carrying with it the mucous membrane of the mouth, should be displaced upward, and fastened with hooks or with a stitch. The tongue should next V)e drawn out of the mouth, with its tip ftistened to the nose, and the liyoid bone drawn downward and also fixed by means of hooks, thus putting the muscular fibers of the tongue on the stretch. All the fat and connective tissue having been removed, the following stractures should be carefully examined : The hyo-glossus, stylo-glossus, and genio-hyo-glossus muscles, the lingual vein, the hypo-glossal nerve, the gustatory or lingual nerve, the .submaxillary ganglion, Wharton's duct, the deep portion of the submaxillary gland, the sublingual gland, the ranine and sublingual artcrit'.s. The hyo-glossus is a thin, flat, sciuare-shaped muscle, arising from the side of the body of the hyoid bone and from its greater and lesser cornua. It is inserted into the iiosterior half of the side of the tongue between the stylo-glossus and lingualis muscles. Its fibers ascend almost perpendicularly from their origin to their insertion, and mingle with the fibers of the palato-glossus and stylo-glossus muscles. The fibers arising from the body of the hyoid bone, termed the basio- glossus, pass upward and backward, and overlap those which arise from the greater cornu, termed the kerato-glosms, which are directed obliquely forward. Those fibers which arise from the lesser cornu are termed the chovdro-glossus, and are separated from the remainder of the muscle by a few filjers of the genio-hyo-glossus muscle ; they are covered by the fibers arising from the body of the hyoid bone. Nerve Supply. — From the hypo-glossal nerve. Blood Supply. — From the lingual artery. Action. — It draws the side of the tongue downward, and when the tongue is protruded it draws it back into the mouth. Relations of the Hyo-glossus Muscle. — Upon the outer surface of the muscle are the hypo-glossal nerve and the small branch which ascends to the stylo- glossus muscle, the gustatory or lingual nerve, the loop of communication between the gustatory and hyo-glossal nerves, the .submaxillary ganglion, the submaxillary gland, Wharton's duct, the hyoid brand i df the lingual artery, the lingual vein, the sublingual gland, the posterior belly of the digastric, the .stylo-hyoid, stylo-glossus, and niyo-hyoid naiscles. Its deep surface is in contact with the genio-hyo-glossus, lingualis, middle constrictor muscle of the pharynx, ])art of the origin of the superior constrictor muscle, the lingual artery, the glosso-pharyngeal nerve, and the PLATE XXIII. Stylo-glossus m. Palatoglossus m. Lymphoid tissue at base of tongue Ciicumvallate papillae Dorsum of tongue Hyoid bone Mylo-hyoid m. Genio-hyoid m. Genlo-hyo-glossus m. EXTRINSIC MUSCLES OF TONGUE. 109 DISSECTION OF THE NECK. Ill stylo-hyoid ligament. At the jiosterior lidnkT of tlir liyo-glossus niusclt' niay be seen the lingnal artery, the .uln^^so-pliaryn^eal nerve, .■md tlic stylo-hyoid ligament pas-sing beneath the muscle. At the anterior border may be seen the loop ol' com- munication between the gustatory and hypo-glossal nerves, tlie brandies of which can be traced to the under surface of the tongue ; and the ranine artery, emcig- ing from l)eneath the anterior liorder of the hyo-glossus muscle. The stylo-glossus muscle — the smallest of tlie three muscles which arise from the styloid process — has its origin from the front and outer side of that process near its apex and from the stylo-maxillary ligament. Its fibers puss downward and forward, and then run almost horizontally to be inserted along the side of the tongue, superficial to the hyo-glossus muscle and as far forward as the tip of that organ ; they blend with the fibers of the lingualis muscle. Beneath the lower jaw the stylo-glossus muscle is crossed by tlie gustatory or lingual nerve. Nerve Supply. — From the hypo-glossal nerve. Blood Supply.— From the nmscular branches of the facial artery. Action. — When both nmscles act together they raise the back of the tongue toward the roof of the mouth. When the tongue is protruded, they draw it back into tlu' moutli. They also draw the sides of the tongue uiiward, thus helping to make it transversel}' concave. The genio-hyo-glossus muscle, the largest of the muscles of the tongue, is triangular in slia[)e, with its a[)ex attached to the lower jaw, and its l)ase to the tongue and the hyoid bone. It arises from the upper genial tubercle on the inner aspect of the symphysis of the lower jaw, immediatelj'^ above the genio-hyoid muscle. The fibers diverge from their origin, the inferior fibers passing dow nward to be inserted into the l)ody of the hyoid lione, the nnddle fibers into the side of the pharynx, and the superior fibers into the tongue from the root to the tip. In relation with the external surface of the muscle are the stylo-glossus, h3'o-glossus, and lingualis muscles, the lingual artery, the hypo-glossal and gustatory nerves, the sublingual gland, and the submaxillary or Wharton's duct. It is separated from the genio-hyo-glossus muscle of the opposite side by the filirous septum, — the srp- (>iin lingua:', — wliich extends through tlie middle of the tongue. Below it is the genio-hyoid muscle. Nerve Supply. — From the hypo-glossal nerve. Blood Supply. — From the lingual artery. Action. — By the simultaneous action of all tlie fibers of the muscle attached to the tongue that organ is depressed and its upper surface grooved. The fibers inserted near the base of the tongue protrude it, while these attached near the tip retract it after if has been jirotruded. The inferior fibers aid the genio-hyoid and anterior belly of the digastric muscle in pulling the hyoid bone upward and 112 SURGICAL ANATOMY. forward ; acting from below, they tend to depress the chin. Contraction of tijis muscle in epileptic convulsions causes the tongue to proti'ude from the mouth, and it may thus be bitten. In certain fractures of the lower jaw, as well as in some operations about the tongue and floor of the mouth in which the origin of this muscle is detached, the tongue has a tendency to fall backward over the superior aperture of the larynx, and respiration may be embarrassed. During anesthetiza- tion the base of the tongue at times falls Ijackward, and breathing becomes labored ; by carrying the angles of the lower jaw forward, the genio-liyo-glossus muscles are made to pull the tongue forward, and thus to relieve the difficulty. If the genio-hyo-glossus muscle of one side is paralyzed and the patient is asked to protrude the tongue, the sound muscle pulls its own side of the base of the tongue forward, whereas the other side is not acted upon ; the tip of the organ will con- sequently protrude toward the paralyzed side. The lingual vein arises near the tip of the tongue, where it is also known as the ranine vein. It receives a branch of the superior thyroid vein and the vense comites of the lingual artery, the tributaries of which correspond to the branches of the lingual artery. It accompanies the hypo-glossal nerve over the outer surface of the hyo-glossus muscle, which separates it from the lingual artery. It passes beneath the stylo-hyoid and posterior belly of the digastric muscle, and empties into the internal jugular or facial vein. When the lingual vein empties into the internal jugular vein, it crosses the external carotid artery at about the level of the greater cornu of the hyoid bone. The hypo-glossal nerve. — Its course as far as the point where it passes beneath the posterior border of the mylo-hyoid muscle has been described. In the submaxillary triangle it lies on the hyo-glossus muscle, accompanied by the lingual vein, and communicates witli the gustatory or lingual nerve at the anterior border of that muscle, from which point it continues forward to the tip of the tongue in the substance of the genio-hyo-glossus muscle. The gustatory or lingual nerve is a branch of the inferior maxillary division of the fifth nerve, and for some little distance from its origin it lies in the pterygo- maxillary region. This portion of the nerve has been described under the Dissec- tion of the Pterygo-maxillary Region. Passing between the ramus of the lower jaw and the internal pterygoid muscle it leaves the pterygo-maxillary region, inclines forward along the side of the tongue, and runs upon the superior constrictor muscle of the pharynx and between the stylo-glossus muscle and the deep portion of the submaxillary gland. It next crosses the upper part of the hyo-glossus muscle ami ^\'harton's duct, whence it jiasses between the mylo-hyoid nniscle and the mucous mend)rane of the floor of the mouth along the side of the tongue to its ti}). Two or more branches connect the gustatory nerve with the submaxillary DISSECTION OF THE NECK. 113 ganglion near the root of the tongiu\ wliilo near the anterior horder of the hyo- glossus muscle it forms a loop with the hypo-glossal nerve. It suiiplies the mucous menihrane of the mouth, the lower gums, and the sub- lingual and submaxillary glands, and gives off branches which ascend through the muscular substance of the tongue to the tiliform and fungiform papilltc. The branches to the sublingual and submaxillary glands contain secreto-motor fibers, which, when stimulated, increase the secretion of these glands. The lingual is the common sensorj' nerve of the tongue, and contains taste fibers foi' the anterior two-thirds of that organ. The submaxillary ganglion is small, and is situated upon the hyo-glossus muscle, between the gustatory nerve and the deep portion of the submaxillary gland and beneath the posterior border of tiie mylo-hyoid muscle. Like the other ganglia of the head, it is connected with the branches of the trifacial nerve and receives filaments of communication of three kinds — viz., motor, sensorj^ and sym- pathetic. Its motor root arises froni the facial nerve through the chorda tj'mpani ; the sensory branches are derived from the gustator}' or lingual nerve ; its connec- tion with the sympathetic nerve is through a branch which comes from the nervi molles around the facial arter}'. Its branches of distribution, five or six in number, supply the mucous membrane of the floor of the mouth, and the sub- maxillary gland and its duct. Wharton's duct, the duct of the submaxillary gland, is about two inches long, and has its origin in the deep portion of the gland. It winds around the posterior or free border of the mylo-hyoid muscle, then lies on the hyo-glossus muscle, between the hypo-glossal and gustatory nerves, under cover of the mylo- hyoid muscle ; thence it passes forward over the genio-hyo-glossus muscle, and beneath the gustatory nerve and sublingual gland, terminating in a constricted opening, situated on a small papilla in the floor of the mouth at the side of the lingual frenum. Near its termination it is joined by one of the ducts of the sub- lingual gland — the duct of Bartholin. The submaxillary gland. — The deep portion of the submaxillary gland turns forward around the posterior or free border of the mylo-hyoid muscle, lying between it and the hyo-glossus muscle. The sublingual gland, the smallest of the three salivary glands, lies upon the mylo-hyoid muscle beneath the mucous membrane of the floor of the mouth at the side of the lingual frenum, where it produces an oblong prominence. It is in contact, on its inner side, with the hyo-glossus, genio-hyo-glossus, and stylo-glossus muscles, the gustatory nerve, and the duct of the submaxillary gland. On its outer side it is in relation with the sublingual fossa in the body of the lower jaw and with the mylo-hyoid muscle ; behind, with the deep portion of the submaxil- S_ii-8 114 SURGICAL ANATOMY. laiy gland, touching the other sublingual gland in the mesial plane. It measures about one and one-half inches in its long diameter, and weighs about one dram. Its ducts — dudi Rivini — are from ten to twenty in number, and open separately on the ridge at each side of the lingual frenum, with the exception of two or more which join to form the dud of Bartholin, \ih\ch. opens either near or into Wharton's duct. Blood Supply. — From the lingual and suljmental arteries. Nerve Supply. — From the gustatory, chorda tympani, and sympathetic nerves. Obstruction of the salivary ducts. — The duet of the submaxillary gland may become obstructed by a calculus, and give rise to a hard and painful swelling over the site of the duct, perceptible through the submaxillary triangle and through the floor of the mouth. Obstruction and dilatation of one of the several ducts opening at the side of the lingual frenum will occasion a cystic swelling known as ranula ; this condition may also be due to an obstructed mucous follicle. Dissection. — Detach the hyo-glossus muscle from the hj^oid bone and lift it up, Avhen the structures in relation with the deep surface may be seen ; these are the horizontal portion, and the commencement of the ascending portion, of the lingual artery, part of the genio-hyo-glossus muscle, the lingualis muscle, the origin of the middle constrictor muscle of the pharynx, the glosso-pharyngeal nerve, and the stylo-hyoid ligament. The horizontal or second portion of the lingual artery rests upon the middle constrictor of the pharynx and the genio-hyo-glossus muscle, below the level of the glosso-pharyngeal nerve, and is covered by the tendon of the digastric, the stylo- hyoid, and the hyo-glossus muscle. From this portion the dorsalis linguse artery is given off, which ascends to the base of the tongue to supply the mucous membrane back of the circumvallate papillae, the tonsil, and the soft palate. It anastomoses with the dorsalis linguae of the opposite side, but this anastomosis is so fine that but slight bleeding follows severance of the tongue accurately in the median line. The ascending or third portion of the lingual artery commences beneath the hyo-glossus muscle. It rests u]>on the genio-hyo-glossus, and passes tortuously between the genio-hyo-glossus and the lingualis muscle to the tip of the tongue, being covered only by the mucous membrane of the under surface of this organ. This portion gives off the sublingual artery and continues as the ranine. The ranine artery, the continuation of tiie lingual artery, passes to the tip of the tongue along the outer side of the genio-hyo-glossus muscle, running between it and the lingualis muscle, and is accompanied by the ranine vein and the ter- minal portion of the gustatory nerve. Near the tip of the tongue it anastomo.ses DISSECTION OF THE NECK. 115 witli tlic ranine artery ol" Hk' opposite side, and on its way supplies the adjacrnt musi-k'S and nmeous nicnilirane. Tlie sublingual artery, smaller than the ranine, arises near the aulerinr hor- der of the hyo-glossus muscle, and runs outward and forward over the oral surfac-e of the mylo-hyoid muscle to reach the sublingual gland. It supplies the sublin- gual gland, the mylo-hyoid muscle, the mucous membrane of the floor of the mouth, and the gums. It anastomoses with the opposite sublingual artery, and with the submental branch of the facial artery, after having perforated the mylo- hyoid muscle. The artery of the frenum is usually a branch of the sublingual artery. It is sometimes wounded in operating for " tongue tie." The best way to divide the lingual frenum so as to avoid wounding the vessel is to place the child upon its back in the mother's lap, and, with the head held tightly between the knees of the operator, to engage the frenum in the slot of a grooved director, by means of which the point of the tongue can be held up. The frenum is thus made tense, and at its attachment to the lower jaw is then simply nicked with a pair of blunt scissors, after which any additional separation which may be required can be done with the finger nail. The stylo-pharyngeus muscle, long and slender, arises from the inner side of the base of the styloid process, and is the longest of the three muscles arising therefrom. It passes downward and forward, and disappears between the middle and superior constrictor muscles of the pharynx. Some of its fibers join the palato- pharyngeus muscle, to be inserted into the posterior border of the thyroid cartilage. The remaining fibers become connected with the fibers of the constrictor muscles of the pharynx. Running along its outer side is the glosso-pharyngoal nerve. In order to reach the tongue, to wdiich it is partly distributed, the nerve passes over the muscle, supplying it with twigs. The stylo-hyoid ligament is a fibrous cord which passes from the tip of the styloid process to the lesser cornu of the hyoid bone. It maj^ be seen lying near the anterior border of the stylo-pharyngeus muscle, and passing beneath the hyo- glossus muscle to the lesser cornu of the hyoid bone. It is the continuation of the styloid process ; it maj' contain nodules of cartilage, and may be largely ossified, forming an unusually long styloid process. Dissection. — Cut off the styloid process at its base, and reflect it downward with the attached muscles and the stylo-hyoid ligament. The glosso-pharyngeal nerve. — Running along the posterior border of the stylo-pharyngeus muscle, and crossing in front of it, is the glosso-pharyngeal nerve. It cur\'es upon the side of the neck, the convexity being directed downward and backward ; it resembles in this respect the hypo-glos.sal and superior laryngeal 116 SURGICAL ANATOMY. nerves. The principal landniarlv for findinp; tliis nerve is the stylo-pharyngeus muscle, around M'hieh it curves, licyund the stylo-pharyngeus muscle the glosso- pharyngeal nerve lies on the middle constrictor muscle of the pharynx. The ter- minal portion of the nerve lies beneath the hyo-glossus muscle, where it divides into two terminal lingual branches, one supplying the mucous membrane covering the posterior third of the dorsum of the tongue, and the other the mucous mem- brane of the side of the tongue, inosculating with the lingual nerve. The glosso- pharyngeal is a nerve of motion, sensation, and special sense (taste) : of motion, to the muscles of the j^harynx ; of sensation, to the mucous membrane of the fauces, tonsil, and pharynx ; and of taste, to the base of the tongue and the fauces. It leaves the cranial cavity by way of the middle compartment of the jugular foramen, clothed by a separate sheath of the dura mater, and lying in advance of, and a little internal to, the pneumogastric and spinal accessorj' nerves. Having made its exit from the foramen, it descends between the internal jugular vein and the internal carotid artery, crosses over the latter vessel obliquelj', and passes beneath the styloid process and the muscles arising therefrom, to reach the posterior border of the stylo-pharyngeus muscle, as previously described. Upon the trunk of the nerve in the jugular foramen are two ganglia : an upper, the jugular, and a lower, the petrous. The former is inconstant, and lioth are considered analogous to the ganglia on the posterior roots of the spinal nerves. At the petrous ganglion (ganglion of Andersch), the glosso-pharyngeal nerve is con- nected with the pneumogastric and sympathetic nerves by communicating branches. The branches of the glosso-pharyngeal nerve, other than the terminal lingual and the communicating, are the meningeal, tympanic, carotid, pharyngeal, muscular, and tonsillar. The meningeal branches arise within the cranial cavity, and are distributed to the pia mater and arachnoid. The tympanic branch {Jacobson^s nerve) arises from the petrous ganglion, and passes to the inner wall of the tympanum through a bony canal (the tympanic canaliculus) the orifice of which is situated upon the ridge of bone between the carotid canal and the jugular fossa. It ramifies ujion the promontory of the tym- panum, forming the tympanic plexus, which supjdies branches to the round and oval windows, and to the Eustachian tube, and communicates with the carotid plexus and with the great and small superficial petrosal nerves. The carotid branches surround the cervical portion of the internal carotid artery, and communicate with the pneumogastric and sympathetic nerves. Tiie pharyngeal branches, three or four in nuinlicr, join l>rnnehos from the pneumogastric, superior laryngeal, and sympathetic nerves, and from the pharyn- geal plcms, which supplies the pharynx. PLATE XXIV. Anterior belly of digastric m. Inferior labial v Mylo-hyoid m Sterno-hyoid m. Omo-hyoid m Sterno-thyroid m L Sterno-mastoid m Sterno-thyroid m.' // Infrahyoid v. Communicating vein from submental or facial vem Anterior jugular v. Communicating br. between anterior jugular veins SUPERFICIAL STRUCTURES NEAR MEDIAN LINE OF NECK. 117 DISSECTION OF THE NECK. 110 The muscular branch .supiilie.s the stylo-pharyngevis muscle. The tonsillar branches arise under tlie hyo-glossus muscle, and are distributed to and around the tonsils, forniin<^ a plexus from whieh 1)rauehes to the fauces and soft palate are derived. The communicating branches ai'ise from the petrous ganglion, as stated, and run to the superior cervical ganglion ; to the auricular branch of the pneumogas- trie, forming a loop; an inconstant l)raneli to the ganglion of (lie root of the pncu- mogastric nerve ; and ont^ fruni the nerve just below the ganglion, to join the lingual branch of the facial nerve. Tlie lingual branches proceed from the end of the glosso-pharyngeal nerve, and are, therefore, its terminal tilaments. They are distrilmted mainly to the circum- vallate papillte, while some filaments supply the follicular glands of the tongue and the front of the epiglottis. Others inosculate around the foramen ctecum with those of the same nerve of the opposite side. The Internal Carotid Artery, tlie larger of the two terminal divisions of the common carotid, ascends perpendicularly b}' the side of the pharynx to the base of the skull, where it enters the carotid canal, in the petrous portion of the temporal bone. It lies at first on the outer side of the external carotid artery, and then lieluml it. At its origin it is more superficial than elsewhere, and lies in tlie superior carotid triangle ; but as it ascends it lies more deeply, passing beneatli the parotid gland, the posterior belly of the digastric muscle, styloid process, stylo- pharyngeus and stylo-hyoid muscles. It is crossed by the hypo-glossal and glos.so- pharyngeal nerves, and the occipital and posterior auricular arteries. Externally it is in close relation with the inti'rnal jugular vein and the pneumogastric nci-ve, and near the ba.se of the skull with the glosso-pharyngeal, hypo-glossal, and spinal accessory nerves ; behind, with the rectus capitis anticus major muscle, the superior ganglion of the sympathetic nerve, and the superior laryngeal nerve ; internally, with the pharynx, the tonsil, and the ascending pharyngeal artery ; in front it is covered by the skin, fasciae, parotid gland, and .the structures which pass between it and tlie external carotid artery — tlie stylo-glo.s.sus and stylo-pharyngeus niuselcs, the glosso-pharyngeal nerve, and the stylo-hyoid ligament. Dissection. — The deep fascia upon each .side of the median line of the neck having been removed, the anterior belly of the orao-hyoid, the sterno-hyoid, sterno-thyroiil, and thyro-hyoid muscles will be exposed. The omo-hyoid muscle consists of two bellies, an anterior and a posterior, connected by an intervening tendon. The anterior belly, which is exposed in this dissection, commences at the tendon intervening between the two bellies of the muscle beneath the sterno-mastoid muscle and in front of the carotid sheath, on a level with the cricoid cartilage. It passes upward along the outer border of 120 SURGICAL ANATOMY. the sterno-hyoid and over the sterno-thyroid and thyro-hyoid muscles, to be inserted into the lower border of the body of the hyoid bone external to the sterno-hyoid muscle. It lies beneath the superficial layer of the deep fascia and sterno-mastoid muscle, and in front of the thyro-hyoid and sterno-thyroid muscles and the carotid sheath. It may be absent or double, or may blend with the adja- cent sterno-hyoid muscle ; occasionally it receives an accessory slip from the manu- brium sterni, or sends one to the lower jaw. The posterior belly of the muscle has already been seen crossing the posterior triangle just above the clavicle, and dividing it into the occipital and subclavian triangles. It arises from the upper border of the scapula, behind the supra-scapular notch, and from the transverse ligament, and may have an additional origin from the upper surface of the middle third of the clavicle. It terminates in the tendon of the omo-hyoid muscle which crosses the carotid sheath. It is covered by the superficial layer of the deep fascia, trapezius muscle, clavicle, subclavius muscle, sterno-mastoid muscle, external jugular vein, and the descending superficial branches of the cervical plexus of nerves. It pas.ses over the first digitation of the serratus magnus muscle and third part of the subclavian artery, the transversalis colli and supra-scapular arteries, the supra-scapular nerve, the cervical trunks of the brachial plexus, the scaleni muscles, the prevertebral fascia, and the carotid sheath. The intervening tendon is bound down by a process of the deep fascia, attached to the clavicle and first rib. Action. — It draws the hyoid bone downward and assists in making tense the lower portion of the deep cervical fascia, thus diminishing the atmo.spheric pressure upon the large veins at the root of the neck and favoring the return cir- culation. Nkrve Supply. — It is supplied by the descendens hypoglossi and the com- municantcs hypoglossi nerves. The sterno-hyoid muscle arises from the posterior surface of the upper part of the manul)rium sterni, the posterior sterno-clavicular ligament, and the posterior surface of the inner extremity of the clavicle. Its fibers pass upward and inward to be inserted into the lower border of the body of the hyoid bone. It has, at times, a tendinous intersection in its lower part. It lies beneath the skin and fascia), anterior jugular vein, sterno-mastoid muscle, sterno-clavicular joint, and the manubrium sterni ; in front of the sterno-thyroid, thyro-hyoid, and crico-thyroid muscles, the thyroid and cricoid cartilages, the thyro-hyoid and crico-thyroid mem- bi'aiies, the pretracheal fascia, trachea, isthmus of the thyroid body, and inferior thyroid veins. Nerve Supply. — From the loop between the descendens and communicantes hypoglossi nerves. DISSECTION OF THE NECK. 121 Blood Supply. — Fnun ln-aiKluvs i)f' the superior thyroid artery. Action. — It draws the iiyuid l)oiie downward, as al'ter swallowinp,-. In laliored respiration it will aet as an elevator of the stermini, heing an accessory nuisele of respiration. The sterno-thyroid muscle is wider and shorter than the sternodiyoid muscle, beneath which it lies. It arises from the posterior sui'face of the ui)per part of the manubrium sterni and the cartilage of the first rib, below, and internal to the sterno-hyoid muscle. Its fibers pass upward and outwaid, and are inserted into the obli(iue line on the side of the thyroid cartilage, where it is continuous with the thyro-hyoid muscle. In the inferior carotid triangle the outer border of the muscle partly overlaps the sheath of the common carotid artery. It lies beneath the skin and fascia3, the nianubiium sterni, anterior jugular vein, sterno-mastoid, sterno-hyoid, and anterior l)elly of the omo-hyoid muscle, and in front of the thyroid and cricoid cartilages, the crico-thyroid muscle, the inferior constrictor muscle of the pharynx, thyroid gland, inferior thyroid veins, pretracheal fascia, trachea, common carotid artery, and left innominate vein. This muscle may be absent or double. Nerve Supply. — From the ansa hvpoglossi. Action. — It draws the thyroid cartilage downward, as after swallowing, and assists the crico-thyi'oid muscle in making tense the vocal cords, by drawing the thyroid cartilage downward and forward. It is an accessory muscle of respiration. The interspace between the internal borders of the sterno-hyoid muscles is wider at the sternum than at the hyoid bone, while the interspace between the inner margins of the sterno-thyroid muscles is wider above than at the sternum ; a lozenge-shaped intermuscular space is thus formed. The thyro-hyoid muscle, apparently an extension of the sterno-thyroid mus- cle, arises from the obIi(iue line on the side of the thyroid cartilage. Its fibers ascend and are inserted into tlie lower border of the body and the inner half of the greater cornu of the hj'oid bone. The sterno-mastoid, sterno-hyoid, and the an- terior 1 jelly of the omo-hyoid muscle pass over the outer surface of the thyro-hyoid muscle ; the superior laryngeal vessels and nerve, the thyro-hyoid membrane, bursa, and the thyroid cartilage lie beneath it. Nerve Supply. — From the hypo-glossal nerve. Blood Supply. — From the hyoid, the sterno-mastoid, and the crico-thyroid branches of the superior thyroid artery, and the liyoid branch of the lingual artery. Action. — It raises the thyroid cartilage toward the hyoid bone preparatory to swallowing, and in conjunction with the sterno-thyroid muscle it dei)resses the hyoid bone and larynx. Dissection. — Divide the sterno-hyoid and sterno-thvroid muscles at their 122 SURGICAL ANATOMY. middle, and reflect them upward and downward. This exposes, from above down- ward, the thyro-hyoid membrane, pierced upon each side by the internal branch of the superior laryngeal nerve and the superior laryngeal artery ; the thyroid cartilage ; the crico-thyroid membrane, upon which are the crico-thyroid arteries ; the cricoid cartilage, partly concealed by the crico-thyroid muscles ; the first, and at times the second, ring of the trachea ; the thyroid gland, its middle portion, or isthmus connecting the two lateral lobes ; the trachea, covered by a plexus of veins formed by the anastomoses of the inferior thyroid veins ; the middle thyroid artery, when present, and the pretracheal fascia. The Thyroid Gland or Body, a ductle.ss and very vascular structure, is situated on the front and sides of the upper part of the trachea, and the sides of the lower part of the larynx. It con,sists of two lateral lobes and a middle lobe, or isthmus, and weighs from one to two ounces. Each lateral lobe is about two inches in length, one and one-fourth inches in breadth, and three-fourths of an inch in thickness. Each lateral lobe is pyriform or cone-shaped, the apex directed upward ; it extends from the fifth or sixth ring of the trachea to the laiddle of the side of the thyroid cartilage. It is convex anteriorly, and is situated between the trachea and the sheath of the common carotid artery, and is covered anteriorly by the sterno-hyoid, the sterno-thyroid, and the anterior belly of tlie omo-hyoid muscle. Its deej"! sur- faces is concave, and in contact with the trachea, larynx, pharynx, esophagus, infe- rior thyroid artery, and recurrent laryngeal nerve. From its upper part, and most commonly from the left lobe, a conic piece, called the pyramid, at times ascends toward the hyoid bone, to which it is attached by a fibrous band in front of the thyro-hyoid membrane ; this part is at times attached to the hyoid bone by a sli}) of muscle, the levator glandulse thyroideas of Soemmering. The middle lobe, or isthmus, is about one-half of an inch in depth, and rests upon the second and third rings of the trachea. The isthmus varies much in its dimensions, and is sometimes absent. There is a space between the upper border of the middle lobe, or isthmus, and the cricoid cartilage, where the trachea is not covered b)^ the gland ; this portion of the trachea is opened in the high operation of tracheotomy. To perform this operation when the space is covered by the middle lobe, it is nec- essary either to displace the lobe downward or pass two ligatures around it and divide it between them. In some instances, however, the width of the middle lobe, or isthnms, is so great that it covers the trachea almost to the sternum. The low operation of tracheotomy is performed below the isthmus of the gland. That this operation is tlic more difficult of the two will be seen at a glance in the dissected neck ; this is due to tin; increasing depth of tlie trnciu^a as it approaches the ster- num, and the presence of the tliyroid plexus of veins in front of this part of the trachea. An abnormally high position of the large vessels at the root of the neck PLATE XXV. Greater cornu of hyoid bone Lesser cornu of hyoid bone Lateral portion of thyro-hyoid membrane Internal laryngeal n Superior laryngeal a Epiglottis ^r*^—* — Hyoid bone Thyroid cartilage Crico-thyroid membrane Crico-thyroid m I \< \^ l.atoral lobe of thyroid gland ^ ^J Trachea ffil {■ Isthmus of thyroid gland Central portion of thyro-hyoid membrane nferior constrictor m. of pharynx uperior thyroid a. ico-thyroid a. ator glandulae thyroideae cold cartilage nferior thyroid veins THYROID BODY. 123 DISSECriOX OF THE NECK. 125 woulil ailil to the difficulty ami ihingcr of the low operation. The tliyroid .silaiid is closely atlaclicd l>y ari'olar tissue to the sides of the ti'achea ami tiie ericoiil :nid thyroid curtilages. During deglutition it rises and falls witii the larynx — a fact of the utmost value in the ditt'erential diagnosis between cervical tumors and enlargement of this gland. It varies in size in different individuals and at differ- ent periods of life, being relatively larger in children ami in females. It often enlarges during menstruation, owing to increased distention of the hlood vessels. The right lobe is larger than the left. In old age the gland decreases in size, becomes firmer, and at times contains calcareous substances. AV'hen enlarged, it may displace and compress the trachea, especially if the enlargement take place rapidly, the body of the gland being held down by the sterno-thyroid and omo- hyoid muscles ; or it may displace the great vessels of the neck laterally, so that the connnon carotid artery may be felt pulsating at the outer border of the sterno- mastoid muscle. Venous engorgement may also ensue, and the recurrent laryngeal nerve may suffer from the pressure of an enlarged thyroid gland. Bonnett has practised subcutaneous section of the muscles in some cases of dyspnea caused by a rapidly growing bronchocele (enlarged thyroid gland). Sir Duncan Gibb, on the other hand, because of the fact that the isthmus, or middle lobe, binds together the enlarging lateral lobes of a bronchocele, proposed to divide the isthmus in cases where dyspnea resulted. He performed this operation several times, great relief to the patient ensuing. As the lateral borders of the thyroid gland are in contact with the sheath of the common carotid artery, it follows that the gland, when enlarged, may readily receive transmitted pulsations from that vessel. An error is occasion- ally made by mistaking a pulsating goiter for aneurysm of the common carotid artery. The median lobe of the thyroid gland is developed as a downgrowth of the epithelium from the posterior part of the tongue ; the site from which this starts is indicated in the adult by the foramen caecum of the tongue. The canal thus formed is known as the thyro-glossal duct, or canal of His. Its walls normally disappear, but remains of them are frequently found in the j)yraniidal jtrocess of the thyroid gland. Accessory thyroid glands, occurring near the median line of the neck, in the vicinity of the hyoid bone, and elsewhere in the neck, are regarded as being formed by division of the pyramidal process. Furthermore, certain cystic tumors at the base of the tongue and in the median line of the neck, as well as the rare cases of median cervical fistula, result from incomplete obliteration of the thyro-glossal duct. The deep surface of the thyroid gland being in relation with the lower part of the pharynx and the upper part of the esophagus, the difficulty in swallowing often observed in bronchocele is explained by the direct pressure, and the interference 126 SURGICAL ANATOMY. witli the movements of tlie larynx. luilargenient of the left lohe of the gland is more likely to occasion difficulty in swallowing than a similar condition on the right side, owing to the inclination of the esoj)hagus toward the left. In a case mentioned by Allan Burns, the isthmus was located between the trachea and the esophagus. It is very evident that enlargement of this portion of the gland hold- ing such abnormal relation would occasion great difficulty in swallowing. The author has seen a case of goiter in which the esophagus was so nearly occluded that the patient, an old woman, was no longer able to swallow liquids. Atrophy of the thyroid gland, or its destruction by disease, is apt to be followed by the condi- tion known as myxedema. Absence of the thyroid gland in children causes cretinism and idiocy. The arteries of the thyroid gland — two on each side — are the superior and inferior thyroid. The superior thyroid, a branch of the external carotid artery, ramifies chiefly upon the anterior aspect of the gland, while the inferior thyroid, a branch of the thyroid axis, enters the under and inner surface of the lateral lobe of the gland. A very free anastomosis is established between these vessels, which form a complete network around the acini in the substance of the gland. Occasionally there is a middle thyroid artery (thyroidea3 ima), a branch of the innominate artery or arch of the aorta, which ascends in front of the trachea and enters the isthmus of the gland. The thyroid gland is surrounded by a thin, dense, fibrous capsule, which is derived from the pretracheal fascia and sends processes into the interior which separate the substance into lobules of varying form and size. The vesicles com- posing these lobules are lined by a single layer of columnar epithelium and contain a colloid substance. Increase of this colloid substance constitutes a form of goiter. The nerves of the thyroid gland are derived from the middle and lower cervical sympathetic ganglia, and accompany the inferior thyroid artery. The thyroid veins, three on each side, are the superior, the middle, and the inferior thyroid. The superior and middle thyroid veins cross in front of the common carotid artery, emptying into the internal jugular vein. The inferior thyroid veins descend on the trachea, form a plexus in front of the pretracheal fa.scia, and behind the sterno-thyroid muscles, and empty into the left innominate vein. The numerous and large lymphatics pass to the lymph trunks at the root of the neck. In some cases these lymphatics have been found to contain colloid substance, giving rise to the supposition that they act as ducts of the gland. Thyroidectomy. — In the operation of removal of half of the thyroid gland in eitlicr l)ilatcra! nr unila1ci-al goiter (l)ronch<:>ccle) the incision may be made parallel with tlic anterior l)order of tlie sterno-mastoid muscle, or a transverse curved incision, concave upward, may be carried over the most ])roniinent portion DISSECTIOX OF THE NECK. 127 of tho tumor. The gland being exposed, the superior and inferior thyroid arteries shoidd be carefully freed, and then secured and divided between ligatures. In ex- posing the inferior thyroid artery preparatory to severing it, and in freeing the lower end of the lateral lobe of the gland behind, care must be exercised to avoid injuring the recurrent laryngeal nerve. After attempts to cure a unilateral goiter by the injection of tincture of iodin or by electro-puncture have ffiiled, the inflammation consequeM upon either form of treatment may result in binding the gland tightly to the carotid sheath, or perhaps to the wall of the internal jugular vein. Under these circumstances dis.secting it loose, in attempted removal of the goiter, will be attended by risk of tearing the vein. Where much pei'iglandular inflammation has occurred, the recurrent laryngeal nerve may be involved in the deposit of exudate, this condition giving rise to aj^honia, which is likely to be permanent whether the goiter be removed or not. The recurrent laryngeal nerve, which has been described with the pneumo- gastric nerve, should now be observed passing upward in the groove between the trachea and esophagus and behind and internal to the lateral lobe of the thyroid gland to enter the larynx. The Subclavian Artery. — The origin, course, and relations of the sub- clavian arteries differ uj)on the two sides. The right subclavian is a branch of the innominate artery, and the left of the arch of the aorta. The anterior scalene muscle passes in front of the subclavian artery and divides it into three portions. The first portion is situated between its origin and the inner border of the anterior scalene muscle, the second portion behind the muscle, and the third portion between the outer border of the muscle and the lower border of the first rib. The first por- tion of the artery is the one which differs in course and relations on the two sides ; it will, therefore, be described separately. The right subclavian artery is the shorter of the two. It arises as one of the two terminal divisions of the innominate artery behind the upper border of the right sterno-clavicular articulation. The first portion of the artery lies deep in the neck, and ascends upward and outward to the inner border of the anterior scalene muscle. It is covered in front by the skin, the superficial fascia, the platysma myoides muscle, the superficial layer of the deep fascia, the sternal end of the clavicle, the sterno-mastoid muscle, the anterior jugular vein, the sterno-hyoid and sterno-thyroid muscles, and the posterior process of the deep fascia (prever- tebral fascia) continued forward from in front of the scaleni muscles. It is crossed by the internal jugular and vertebral veins, the pneumogastric nerve, the superior cardiac nerves and a loop of the .sympathetic nerve (ansa "\''ieussenii), and the phrenic nerve. Below the artery are the pleura, the recurrent laryngeal nerve, 128 SURGICAL ANATOMY. and the subclavian vein ; behind it are the recurrent laryngeal nerve, the cord of the sympathetic nerve with its middle and inferior cardiac branches, the longus colli muscle, the transverse process of the seventh cervical or first thoracic vertebra, from which it is separated by a small quantity of cellular tissue and fat, and the apex of the lung, covered with pleura. The left subclavian, the longer of the two arteries, arises from the transverse portion of the arch of the aorta opposite the third thoracic verteljra. Its first portion ascends almost vertically to the inner margin of the first ril) and the inner border of the insertion of the anterior scalene muscle. Only the relations of the cervical part of this portion of the artery will be described here. The cervical part of the first portion is covered by the skin, the superficial fascia, the platysma myoides muscle, the superficial layer of tlie deep fascia, the sterno-mastoid muscle, the anterior jugular vein, the sternodiyoid and sterno-tliyroid muscles, the po.sterior process of the deep fascia, continued forward from in front of the scaleni nmscles, the sternal end of the clavicle, the left internal jugular vein, the vertebral and sub- clavian veins, the apex of the left king and its pleura, the phrenic nerve, and the cardiac branches of the sympathetic nerve, which lie parallel with the artery, the left common carotid artery, and the thoracic duet. On its outer side are the apex of the lung and pleura ; on its iinier side are the trachea, the recurrent laryngeal nerve, the esophagus, and the thoracic duct ; behind it are the pleura and the apex of the left lung, while behind and internal to it are the thoracic duct, the esophagus, the inferior cervical ganglion of the symj^athetic nerve, the sympathetic cord, the longus colli muscle, and the spinal column. Differences Betweai the Right and Left Subclavian Arteries in Their First Por- tion. — The first portion of the left subclavian artery differs from the first portion of the right in the following respects : The left subclavian arises directly from the arch of the aorta, while the right arises from the innominate artery ; it lies deeper, is longer and more vertical ; it is in relation with the esophagus and the thoracic duct, while the right is not ; it is crossed liy the left innominate or brachio-ceplialic vein, the phrenic and ])neumogastric nerves, and the cardiac branches of the sym- pathetic nerve running almost paralk4 with it ; on the right side the phrenic and pneumogastric nerves and some of the cardiac branches of the sympathetic nerve pass in front of the right subclavian artery, at nearly a right angle. The left subclavian artery is not in so close a relation with the recurrent laryngeal nerve as is the right subclavian, the nerve winding around below the latter. In the follow- ing description of the cour.se of the thoracic duet it will l)o seen to be in relation with llic lir.st portion of the loft s;d)clavian artery at two points; it holds, of course, no relation to the I'ight subclavian artery. The thoracic duct passes upward and out of the chest to the left of the PLATE XXVI, Esophagus Trachea (lower portion removed) Thyroid body Scalenus medius m Scalenus posticus m Thoracic duct Vertebral a. Common carotid a. Inferior thyroid a. Internal jugular v. Scalenus anticus m. Internal mammary a. Right innominate v Superior vena cava Innominate a'. Aorta (a) Transversalis colli a. Suprascapular a. Subclavian v. Internal jugular v. (cut) Subclavian a. (1st portion) Vertebral v. Left innominate v. Left bronchus ri— 9 THORACIC DUCT. 129 DISSECTION OF THE NECK. 131 eso[)hagus and beliiml the lirst |)orti()ii of the suhclavian artery ami tlie apex of the left lung. llehind llie left internal jugular vein and eonnuon carotid artery, and opposite the seventh eervieal vertebra, the duet forms an arrli aliove the subclavian artery and anterior to tiie vertebral arteiy and vein, and descends in front of the anterior scalene muscle to empty into tlie left subclavian vein at its junction with the internal jugular vein. The Second Portion of the Subclanan Artery. — The relations of the subclavian artery in its second and tliinl poi'tions are alike on its two sides. In its second portion the artery lies behind the scalenus anticus and in front of the scalenus medius muscle ; at this point it rises highest above the clavicle, usually about three- fourths of an inch. It is covered by the skin, the superficial fascia, the platysma myoides muscle, the superficial layer of the deejj fascia, the clavicular origin of the sterno-mastoid muscle, the jaosterior process of the deep fascia, the phrenic nerve, and the anterior scalene muscle, the latter separating it from the subclavian vein. Above it lies the lower of the three cervical trunks of the axillarj' or brachial plexus of nerves. Behind it are the middle scalene muscle and the apex of the lung and pleura. Below it lies the pleura, while below and in front of it is the subclavian vein. This portion gives off but one branch, the superior inter- costal artery. Tlie Third Portion of the Subclavian Artery. — In the third part of its course the artery passes downward and outward from the external margin of the anterior scalene muscle to the lower border of the first rib, occupying the subclavian tri- angle, where it is nearer the surftice than in either the first or second portion of its course. It is covered by the skin, the superficial fascia, the platysma myoides muscle, the superficial layer and the posterior of the two processes of the deep fascia, and near its termination by the clavicle and subclavius muscle. Running in front of this portion are the supra-scapular artery and vein, while crossing it are the clavicular branches of the cervical plexus, the nerve to the subclavius muscle, and the external jugular vein. The tran.sversalis colli, supra-scapular, pos- terior jugular, and jugulo-cephalic veins, which frequently form a plexus in front of the artery, and should be borne in inind in ligating the third portion of the sub- clavian artery, empty into the external jugular vein. The relation between the supra-scapular artery and the third portion of the subclavian artery at its point of election can be compared, surgically, to the relation held between the middle sterno-mastoid and the connnon carotid artery at its point of election. The ana- tomic difference is, however, that the middle sterno-mastoid arterj^ passes across the sheath of the common carotid, and is frequently severed in the ligation of the latter, wjiile the su]>ra-seapular passes in front of, and almost parallel with, the subclavian artery, and can be displaced when the main vessel is ligatured. The subclavian 132 SURGICAL AXATOMY. vein lies below the artery, and on a jilane anterior to it. Above and to the outer side of this portion of the artery are the tliree ecrvical trunks of the axillary or brachial plexus of nerves and the omo-hyoid muscle. The upper trunk runs so close to and so nearly parallel with the arter}' that it may be mistaken for it and tied, the surgeon being misled by the pulsation communicated to the nerve. Behind the artery are the middle scalene muscle and the lower cervical trunk of the brachial plexus. Below this portion of the artery is the first rib. The third portion of the subclavian artery, as a rule, gives off no branches, but occasionally gives origin to the posterior scapular artery. Variations of the subclavian artery. — Tlie right subclavian artery may arise as a separate trunk from the arch of the aorta. It may pass in front of or through the fibers of the anterior scalene muscle, and ascend as high as one and one-half inches above the clavicle. In some cases the subclavian vein passes with the artery behind the anterior scalene muscle. Ligation of the third portion of the subclavian artery. — The third portion is the jjoint of election for ligation of the subclavian artery ; in this portion it is most superficial, is covered by fewer important structures, and, as a rule, gives off no branches ; the posterior scapular artery occasionally arises from it. When performing this ligation the patient should Ije placed in the supine position, with a pillow beneath the upper part of the back, and the shoulder depressed. The in- cision is made parallel with the upper border of the clavicle, should be three or four inches in length, and commence at the outer border of the clavicular origin of the sterno-mastoid muscle. The vessel is brought nearer the surface by carrj'- ing the arm to the side and depressing the shoulder, thus diminishing the depth of the triangle through which the artery passes. The relation of the supra-scapu- lar vessels to the third portion of the subclavian artery is so changed when the arm is well drawn down that it is not endangered in the ligation. The following structures are divided : the skin, the superficial fascia, the platysma myoides muscle, some of the clavicular branches of the cervical plexus of nei'\'es, the super- ficial layer of the deep fascia, and the posterior of its two processes (prevertebral fascia). The external jugular vein, with tlio veins emptying into it, which frequently form a plexus above and in front of the subclavian artery Viet ween the two layers of the deep fascia (superficial and prevertebral), should be pushed aside ; if this is not feasible, they may be tied and severed between ligatures. The posterior belly of the omo-hyoid muscle should next be exposed by dividing the connective tissue at the bottom of the wound ; tlie operator then searches for the upper cervical trunk lA' the axillary or brachial plexus of nerves and the outer border of the anterior scalene muscle, along wliich the finger is jtassed until the tuliercle on the first rib is reached, provieliinil the intei-iial jugular x'eiii, and runs up the neck close to tlie ti|is of the transverse processes of the cervical vertebra; in the groove between the anterior scalene and the rectus capitis anticus major muscle, and to tin' inner side of the phrenic nerve. DISSECTION OF THE NECK. 1 i:, Its braiH'hos to tlic nmsclrs of tlic neck coniimmiciitc w ilh tin- muscular liranclics of the verteliral artery, wliile ntlK'r;* enter tlie intcrverteliral riFraniiiia, to n'acli tiio bodies of tlie vertebra- ami the spinal cord and its menini;es. It anastomoses with tlie verctehral, ascending i)haryngeal, and branches of the occiiiital artery. It sends a branch to the phrenic nerve. The iiifcriiir luri/iif/cal artcri/ accompanies the retairrent laryngeal nerve, sup- plies the nniscles and uuu-ous inembrane of the lai'ynx, and anastoiiuises with the superior laryngeal artery. The fnifliral bi-diichcs ramity upon the trachea, the lower ones anastomosing with the bronchial arteries. The esophageal hnuiches sujiply the esophagus. One of these is often large, runs parallel with the continuation of tlie inferior thyroid artery, and may be mis- taken for it. The iHuacular bra)iclies supply tlie muscles of the lower anterior part of the neck. The infericir thyroid artery is not accompanied by the corresponding vein, which lies at the side of tlie median line of tlie neck. (See Dissection of Front of Neck.) Ligation of the inferior thyroid artery. — This is performed either where the artery lies between the internal jugular vein and the inner border of the anterior scalene mu.scle, or to the inner side of the carotid sheath as it passes to the deep surface of the lateral lobe of the thyroid gland just below the level of the cricoid cartilage. To secure the inferior thyroid artery along the inner border of the anterior scalene muscle make an incision similar to that made in ligation of the vertebral artery, carrying the aneurysm needle from within outward away from the vertebral vein. To secure the inferior thyroid artery on the inner side of tlie carotid sheath make an incision along the anterior border of the sterno-mastoid muscle. • Tlie supra-scapular artery (transversalis humeri), smaller than the transver- salis colli artery, coarses outward across the lower part of the neck. It first passes beneath the sterno-mastoid muscle and over the phrenic nerve and lower part of the anterior scalene muscle; then it runs behind the clavicle and subclavius muscle, crosses the third part of the subclavian artery, and pa,sses beneath the posterior belly of the omo-hyoid and the anterior border of the trapezius muscle, to the superior liorder of the scapula, where it passes over the transverse ligament of that lioiie to reacli the supra-spiiious fossa. The .supra-scapular nerve, which joins the artery just before it dips under the onio-h\-oid muscle, passes beneath the transverse ligament, and through the supra-scapular notch. In the supra-spinous fo.ssa the artery lies close to the bone, and supplies the supra-spinatus muscle ; at S— 11-10 146 SURGICAL ANATOMY. the neck of the scapula it turns around the base of the spine to the infra-spinous fossa, where it anastomoses with the dorsahs scapulae, a branch of the subscapular artery, and with the posterior scapular artery. The chief Branches of the sujira- scapular artery are the inferior sterno-mastoid, supra-acromial, and articular. Other branches supjjly the subclavius muscle, the skin over the manubrium sterni (suiara-sternal), and the clavicle. The inferior sterno-mastoid artery supplies the clavicular jiortion of the sterno- mastoid muscle, behind which it is given off. The supra-acromial branch pierces the trapezius muscle, passes over the acromion process, and anastomoses with the acromio-thoracic and posterior circum- flex arteries. The articular branches sujaply the acromio-clavicular joint and the shoulder- joint. The transversalis colli artery, or transverse cervical, usually larger than the supra-scapular artery, passes outward across the side of the neck, higher than the supra-scapular, over the scalene muscles and phrenic nerve, and over or between the cervical trunks of the axillary or brachial plexus to the anterior border of the trapezius, beneath which, and at the outer border of the levator anguli scapulae muscle, it divides into its two terminal Ijranches, the superficial cervical and the posterior scapular. The superficial cervical artery passes upward beneath the anterior border of the trapezius and over the levator anguli scapula; and splenius muscles. It supplies these muscles and the posterior chain of lymphatic glands in the neck, and anas- tomoses with the suj^erficial branch of the arteria princepS cervicis, which descends from the occipital artery between the .splenius and complexus muscles. The posterior scapular artery, the larger of the two terminal branches, passes beneath the trapezius and the levator anguli scapulas muscle to the superior angle of the scapula, whence it descends along the vertebral border or base of the scapula to the inferior angle. It runs between the insertions of the serratus magnus muscle in front and the rhomboidri and levator anguli scapuUe muscles bi'liind, which, with the latissimus dorsi and trapezius, it supplies. It anastomoses \\itli the supra-scapular and subscapular arterit's, and with the posterior branches of the intercostal arteries. It frequently arises from the third portion of the sub- clavian artery, and in sv;ch cases the superficial cervical artery usually arises from the thyroid axis. Tlie veins corresponding to the Itranelies of tlie thyroid axis empty into the external jugular vein, exci'iit the inferior tliyroid vein, which goes to the innomi- nate vein. The Internal Mammary Artery arisis from the lower margin of the first DISSECTION OF THE NECK. 147 part of the subclavian arteiy opposite tlie thyroid axis. It passes downward beneatli the elavicle, tlie suliclavius nuiscle, and the subclavian vein, and enters the eliest between tlie cartilage of the first rib and the pleura. At its origin it is cro.ssed from without inward by the jihrenic nerve. Its further course is descril)ed under the Dissection of the Thorax. The accompanying veins of the internal mannnary artery, two in number, unite to form a common trunk which empties into tlie innominate vein. Tiie Superior Intercostal Artery arises from the upper margin of the second portion of the subclavian artery, and occasionally arises from the first portion upon the left side. It arches backward and a little upward over the pleura, and then descends behind it, giving off the profunda cervicis artery ; it tlien passes in front of the neck of the first, and sometimes of the second, rib, giving off the arte- ries of the first, and at times of the second, intercostal space, and a ]>o.sterior branch, which is distributed to the muscles of the back and to the spinal cord and its membranes. In front of the neck of the first rib it lies between the first thoracic sympathetic ganglion on the inner side, and the anterior branch of the first thor- acic nerve on the outer side. Its Branches are the deep cervical, the first inter- costal, and the arteria aberrans. The deep cervical artery (profunda cervicis) passes backward between the seventh and eighth cervical nerves, and then between the transverse process of the last cervical vertebra and the neck of the first rib, internal to the middle and pos- terior scalene muscles ; thence it passes up the back of the neck between the com- plexus and .semi-spinalis colli muscles, which it supplies, and anastomoses with the arteria princeps cervicis and branches of the ascending cervical and vertebral arteries. The deep cervical vein liegins in the suboccipital triangle, usually receives the occipital vein, accomj^anies the arteria princeps cervicis, and then the profunda cervicis artery, and em])ties into the vertebral or innominate vein. The first intercostal artery has a distribution in the first intercostal space corresponding with that of the arteries in the other intercostal spaces. The arteria aberrans, inconstant, arises from the inner side of the right superior intercostal artery, and passes downward behind the esophagus, supplying adjacent structures and sometimes joining a small ascending branch of the aorta. oi)posite the third thoracic vertebra. The anastomosis between the superior intercostal and the occipital artery performs an important part in the development of the collateral circulation after ligation of the common carotid artery. The veins wliieh correspond to the superior intercostal arteries are the right 148 SURGICAL ANATOMY. and left superior intercostal veins. The left superior intercostal vein empties into the left innominate vein, and the right into the vena azygos major or the right innominate vein. The Axillary or Brachial Plexus. — Tlie axillary or brachial plexus of nerves will be seen at the side of the neck, emerging from between the anterior and middle scalene muscles ; it is formed by tlie union of the anterior branches of the lower four cervical nerves and by the greater j^ortion of the anterior branch of the first thoracic nerve. A small branch from the anterior division of the fourth cervical and another from the second thoracic nerve usually enter the plexus. These branches form tlie cords of the plexus, from wlucli are given off the branches that supply the upper extremity. The nerves in the neck are arranged as follows : the anterior branches of the fifth and sixth cervical nerves unite bej'ond the outer border of the anterior scalene muscle to form an upper trunk ; the anterior branch of the seventh cervical nerve remains distinct as the middle trunk ; the anterior branches of the eighth cervical and first thoracic nerves unite between the scalenus anticus and scalenus medius muscles to form the lower trunk. The upper and middle trunks run above and parallel with the subclavian artery, but on a posterior plane, while tlie lower trunk passes behind the artery. The three trunks accompany the artery between the clavicle and first rib on their way to the axilla. These three trunks separate into anterior and poste- rior divisions, the anterior divisions of the upper and middle trunks forming the outer cord, that of the lower trunk continuing as the inner cord, and all the posterior divisions uniting to form the posterior cord. (For a desci'iption of the plexus within the axilla see Dissection of Axilla.) The branches of the axillary or brachial plexus are divided into two sets : tliose given off above the clavicle and those arising below tliat bone. The branches arising above the clavicle are the nerves to the subclavius, rhomboidei, scaleni, and longus colli muscles, the posterior or long tlioraeic nerve (the external respiratory nerve of Bell), conuuunicating, and supra-scapular nerves. The nerve to the subclavius muscle arises from tlie trunk formed by the liftli and sixth cervical nerves, and jiasses downward over tlie tliird portion of the subclavian artery to tlie under .surface of the subclavius muscle. It is frequently connected with the ]ihronic nerve at the lower part of the neck by a filament which passes in fronl nf the subclavian vrin. The nerve to the rhomboidei muscles arises from the fifth cervical nerve, PLATE XXXI Rhomboid n. N, to Levator anguR Scapulae^ Suprascapular n. Upper subscapular Eighth cervical nerve Seventh cervical nerves Nerves to scaleni and Longus colli Sixth cervical n. Nerves to scaleni and Longus colli^ Fifth cervical n. From fourth cervical n. Roots of phrenic n. N. to subclavius \\ \ External anterior thoracic n Internal anterfor thoracic n Musculo-cutanej}) Circumflex n * {Nerves to Scaleni and Longus colli First thoracic n First intercostal n. Posterior thoracic n. Lesser internal cutaneous n. Middle subscapular n. Internal cutaneous n. Lower subscapular n. Utnar n , Musculo-spiral n Median n AXILLARY OF BRACHIAL PLEXUS OF NERVES. 149 PLATE XXXII, Rectus capitis lateralis m. Rectus capitis anticus minor m Posterior belly digastric m.(cut) Trachelo-mastoid m. Carotid tubercle Longus colli m Rectus capitis lateralis m. Obliquus capitis superioris m. Obliquus capitis inferioris m. Splenius capitis m. Rectus capitis anticus major m. Levator anguli scapulae m. PREVERTEBRAL MUSCLES, 152 DISSECTIoy OF THE NECK. 153 pierces the middle scalene muscle, and passes backward beneath the levator anguli scapuLT muscle to the uiuler surface of the rhomboidei muscles, which, with the levator anguli scapuke muscle, it supplies. It accompanies the posterior scapu- lar artery. The nerves to the scaleni and longus colli muscles arist- from the lower three cervical nrrves near the intervertebral ibnunina. The posterior or long thoracic nerve (external respiratory nerve of Bell) arises within the substance of the scalenus medius muscle from the fifth, sixth, and seventh cer\-ical ni'rves. The first two roots pierce the scalenus medius muscle below the nerve to the rhomboidei muscles, and the last root passes in front of the scalenus medius muscle. The long tlioracic nerve passes downward behind the trunks of the axillary plexus and tlie subclavian vessels, and enters tlie axilla Ity way of the apex. Here it lies upon the serratus magnus muscle, which it supplies. Communicating. — Usually a branch from the fifth cervical nerve joins the phrenic nerve on the anterior scalene muscle. Tiie supra-scapular nerve, tlie largest of the branches given off above the clavicle, arises from the upper cervical trunk near the nerve to the sulxdavius mus- cle. It passes downward and outward beneath the traiaezius and the posterior belly of the omo-hyoid muscle to the upper border of the scapula, where it is in relation with the supra-scapular artery. It passes through the supra-scapular notch, being separated from the artery by the transverse ligament, and enters the supra-spinous fossa. It supplies the supra-spinatus muscle, winds around the base of the spine of the scapula, and sends articular liranches to the shoulder-joint, after which it terminates in the infra-spinatus muscle. The scalene muscles. — The scalene muscles are three in number : the anterior, the middle, and the posterior. Tlie anterior scalene muscle arises from the anterior tul)ercles of the trans- verse processes of the third, fourth, fifth, any liie nerve to the subclavius muscle. Tlie supra-scapular artery and vein cross this portion of the artery from within i)ut\vard, and usually lie near the level of the upper border of the clavicle. In this respect the supra-scapular artery bears the same relation to the subclavian artery at the i)oint of election as the middle sterno-mastoid artery does to the common carotid artery at its point of election. Behind this part of th(> artery are the middle scalene muscle, the first rib, and tlu^ lower cervical trunk of the brachial plexus, which is formed by the eighth cervical and the first thoracic nerve. Above it are the upper and middle trunks of the brachial plexus and the posterior belly of the omo-hyoid muscle. The upper cer\'ical trunk uf the l.)rachial jilexus, which lies just above the artery and in an anterior l>lane, may be mistaken for the subclavian artery. Below, it rests against the upper surface of the first rib. The subclavian vein lies below the subclavian artery, but on an anterior plane, and is usually behind the clavicle. In ligating the tliird portion of the subclavian artery the upper part of the thorax should be elevated bj' placing a pillow beneath the shoulders ; the neck should be extended, and the head turned toward the opposite side. The shoulder is next depressed, to make the subclavian triangle shalloAV, and to bring the artery nearer to the surface. The skin should be drawn downward over the clavicle, and a transver.se incision, three inches long, should be carried along that bone, so that when the skin is allowed to retract, the incision will be about one-half of an inch above the clavicle. This method of dividing the skin obviates the danger of injuring the external jugular vein, which crosses the artery close to or under the posterior border of the sterno-mastciid nniscle. The incision should extend from the trapezius to the sterno-mastoid nmscle. It divides the skin, superticial fascia, platysma myoides muscle, supra-clavicular branches of the cervical plexus, some small arteries, and the jugulo-cephalic vein, if present. The superficial layer of the deep fascia is next divided. If a plexus of veins be present, the veins should lie divided Itetween ligatures, and the posterior process of the deep fascia (prevertebral fascia) carefully incised. The posterior belly of the omo-hyoid muscle is located, and the posterior border of the anterior scalene muscle is found, and traced downward to the scalene tubercle of the first rib. The artery may be felt pulsating just external to the tubercle, and is exposed, together with the cer\'ical trunks of the brachial plexus, by a slight dissection. The sheath of the artery being opened, the aneurysm needle is passed around the artery fVoin before backward and belnw ujnvard, to avoid the subclavian vein, which lies below, but in an anterior plane. The needle should be held clo.se to the artery, to avoid inclusion of the lowest trunk of the brachial plexus, which lies behind the artery. 170 SURGICAL ANATOMY. The transversalis colli artery is rarely seen, owing to its high position, while the supra-scapular artery crosses the subclavian artery just behind the clavicle. If either artery is seen, it should be displaced, and not divided; if the external jugular vein causes much difficulty, it should be divided between ligatures. In very muscular subjects it may be necessary to cut through the posterior part of the clavicular origin of the sterno-mastoid muscle. The variations in the position of this portion of the artery should be borne in mind. It usually emerges from beneath the anterior scalene muscle, about one-half of an inch above the clavicle, and descends abruptly ; it may, however, lie almost entirely under the clavicle, or it maj^ ascend as high as one and one-half inches above the clavicle. It occa- sionally gives origin to the posterior scapular artery. That the ligature has been applied to the subclavian artery instead of to a trunk of the brachial plexus is proved by the absence of the pulse beyond the ligature. The Collateral Circulation is established by the anastomoses of tlie — Above. Below. Supra-scapular and . , Acromio-thoracic, posterior circum- Posterior scapular arteries flex, and subscapular arteries. Internal manimarv artery o • ^i • i ^i ^, . . ■ 1 • , buperior thoracic, long thoracic, bupenor intercostal artery with , , , , . , . . , and subscapular arteries. Aortic intercostal artery Irregular Forms. — The right subclavian artery arises at times higher or lower than normally, or may spring directly from the transverse portion of the arch of the aorta as the first, second, third, or fourth branch. "When it is the first branch, the first portion takes the course of the innominate artery and is more deeply situated than normally ; when it is the second or third branch, it usually passes under the common carotid artery ; and when it is the fourth branch, it may pass under the trachea and esophagus, or between the trachea and esophagus, and has been seen arising from the descending portion of the aorta as low as the fourth thoracic vertebra. The left subclavian artery may arise from a short trunk common to it and the left common carotid artery. On each side the subclavian artery may pass in front of or pierce the scalenus anticus muscle ; the subclavian vein may accomjjany the second portion of tlie subclavian artery through or under the scalenus anticus muscle. The second portion may lie under the clavicle, or may rise one and one-half inches above the clavicle. The third portion of the sub- clavian artery frequently gives origin to the po.sterior scapular artery, and occasion- ally to the supra-scapular artery, and in nuiscular persons may be covered by IJie sterno-mastoid and trapezius muscles. A clavicular origin of the posterior belly of the omo-hyoid muscle may lie in front of this ]iortion, and this belly of the PLATE XXXVII Circle of Willis Superficial temporal a. Intern.-J maxillary a. Occipital a External carotid a Princeps cervicis a Internal carotid a. Ligature on common carotid a. Ascending cervical a Superior thyroid a. Vertebral a Common carotid a. Acromio-thoracic a Axilllary a. Subclavian a. -Thyroidea ima (a.) nnominate a. Superior thoracic a. Vas aberrans (a.) Intercostal arteries Aorta (a.) Long thoracic a. Dorsalis scapulae a. bscapular a. nternal mammary a. Posterior circumflex a. COLLATERAL CIRCULATION AFTER LIGATION OF i)UDuLh/iAN AN[ 171 CAROTID ARTERIES, PLATE XXXVIII, Common carotid a iSterno-mastoid m. ^Internal jugular v. . (Vertebral v. /Vertebral a. (Inferior thyroid a. , Scalenus anticus m. /Thyroid axis (a.) /Transversalis colli a. Posterior belly of omo-hyoid m, .External jugular v. Superficial descending branches of cervical plexus of nerves % Platysma myoides m. Superficial layer of deep fascia Prevertebral fascia Suprascapular a. Phrenic n. Subclavian a. (1st portion) Thoracic duct Sterno-mastoid m.(cut) Subclavian v. EXPOSURE OF VERTEBRAL ARTERY AND INFERIOR THYROID ARTERY AT ORIGIN-LEFT SIDE OF NECK, 174 LIGATION OF ARTERIES OF HEAD AND NECK. 175 omo-hyoid may lie close to the elavii'ie in front ol' (he suhelavian arleiy. The exti'inal jugular vein may cross the artery at some distance external to tlie posterior horder of the sterno-mastoid muscle. Guides. — The guides to the third portion of the subclavian artery (the place of election) are the most prominent part of the clavicle behind which il lies, the posterior border of the sterno-mastoid muscle, the outer border ol' the inser- tion of the scalenus anticus muscle into the scalene tubercle of the hrst rib, and the pulsations of the artery. The vertebral artery may be ligatured for wounds, traumatic aneurysm, and aneurysm of the innominate artery and arch of the aorta. Its only accessible portion is deeply situated in the lower part of the neck, where it lies in the groove between the scalenus anticus and longus colli mu.scles. This portion of the artery is in relation, in front, with the vertebral and internal jugular veins, and is crossed on both sides by the inferior thyroid artery and by the thoracic duet on the left side. The vertebral vein crosses in front of the artery just below the transverse process of the sixth cervical vertebra ; it tlien lies in front and to the outer side of the artery as it passes downward to the innominate vein. The relation of this vein to the artery is variable, as the vein may be found on either side of the artery. Behind the artery are the sympathetic nerve cord, the inferior cervical sympathetic ganglion, and the transverse process of the seventh cervical vertebra. To its iimer side is the longus colli muscle, and to its outer side the anterior scalene muscle. It is surrounded by the vertebral sympathetic plexus. In the operation for ligation of the vertebral artery the patient lies in the same position as in ligature of the third j)ortion of the subclavian artery — /. c, with the shoulder elevated, the neck extended, and the face turned to the oj^posite side. The incision should commence at the clavicle, and be carried for three inches upward along the posterior border of the sterno-mastoid muscle. Care is required here to avoid injuring the external jugular vein, which runs under tlie platysma myoides muscle obliquely across the sterno-mastoid muscle to its posterior border, then along that border, piercing the superficial layer of the deep fascia one-half of an inch above the clavicle. The incision divides the skin, superficial fascia, platysma myoides muscle, and descending branches of the cervical plexus. The external jugular vein is exposed and drawn outward, and the superficial layer of the deep fascia divided. It may be necessary to .sever part of the clavicular head of the sterno-mastoid muscle at its origin. The anterior scalene mu.scle is located, and the surgeon carries his finger inward through the interval between the prevertebral fascia and the superficial layer of the deep fascia. The positions of the internal jugular vein, common carotid artery, and transverse process of the sixth cervical vertebra are ascertained. The anterior 176 SURGICAL ANATOMY. tubercle of the transverse process of the sixth cervical vertelji'a (carotid hihcrclc) is the guide to the vertebral artery, fur the reason that it is usually the first transverse process which is entered by the artery. Just below this tul)ercle the groove between the scalenus anticus and longus colli muscles can be felt, and the prevertebral fascia is divided along the inner l)orderof the scalenus anticus muscle. Along tlie inner border of the scaletuis anticus nmscle the inferior thyroid artery can be recognized b}' its jiulsations ; the vertebral artery is detected in tlie same manner, deep in the groove previously mentioned. The vertebral vein and inferior thyroid artery should then be drawn outward, and the needle be passed from without inward. Care is necessary to avoid injuring the internal jugular vein, inferior thyroid artery, vertebral A\'in, pleura, the right lymphatic duct, and, on the left side, the thoracic duct. Tlie phrenic nerve is not endangered, because it lies beneath the prevertebral fascia on the scalenus anticus muscle. Immediately after the artery is tied contraction of the pupil of the same side occurs, due to dis- turbance of the vertebral plexus of the sympathetic nerve. This condition is evidence that the inferior th^'roid artery or its ascending cervical branch has not been ligatured instead of the vertebral arteiy. Irregular Forms. — The left vertebral artery may arise from the subclavian artery at a point unusually near either to tiie origin or the termination of the first portion of the left subclavian artery. It may arise from the arch of the aorta or the left common carotid artery. The right vertebral artery occasionally arises nearer to the bifurcation of the innominate artery or to the inner margin of the scalenus anticus musck'. A\'hen the right subclavian artery arises from tlie aortic arcli, the right vertebral arter}' may arise from the right common canitid artery or from the arch of the aorta. When it arises from the left side of the aortic arch, it may pass behind the esophagus. Either vertebral artery may arise from the subclavian as two branches, which later unite, or the vertebral artery may divide while passing upward in the trans- verse processes, one branch entering the spinal canal with the second cervical nerve, and the otlier pursuing the normal course of the vertebral artery. On each side the vertebral artery frequently enters tlie passageway in the cervical trans- verse processes, at some other than at tlie sixth cervical transverse process. It may first enter any of the cervical transvei'se processes from the second to the seventli inclusive. When the artery first enters the seventh cervical transverse process its ligation is difficult, and wlien it enters above the sixth, the artery lies nearer to the esophagus than nnrinally. The vcrtt'bral artery rarely gives origin to the inferior thyroid, superior intercostal, jjrofunda cervicis, or occipital artery. One vertebral artery may be larger than the artery of the ojjposite side. Guides. — The guides to the vertebral artery are the posterior border of the PLATE XXXIX, Submaxillary gland Hypoglossal Lingual ; Digastric tendO' Stylo-hyoid r Hyoglossus m. old m. stric tendon perficial layer of deep fascia Platysma myoides m. Internal laryngeal n Extornil laryngeal n. External carotid a. Superior thyrord a. Superior thyroid veins Middle sterno-mastoid a. Superficial layer ■ ' ■'="'' f->^^.. Platysma myc; Superficial layer of deep fascia Anterior belly omo-hyord m Thyroid body Inferior thyroid a Sterno-mastoid m Prevertebral fascia Anterior jugular v. Branch of ansa hypoglossi (n.) Common Carotid a. LIGATION OF {]) FIRST AND SECOND PORTIONS OF LINGUAL ARTERY; (2) SUPERIOR THYROID ARTERY; (3) INFERIOR THYROID ARTERY, 177 s— Jl— 12 LIGATION OF ARTERIES OF HEAD AXD NECK. 179 sterno-niastoid muscle and tlie canitiil tubrrclo or aiitcrinr tulKTcle of the sixth cervical transverse process, which lies at tlic n})per extremity of tiic groove l)et\veen the scalenus anticus and longus colli muscles. The inferior thyroid artery may be ligatured to arrest the growth of the tlivroid body in goiter, and for wounds of this body. It is more commonly liga- tured in the removal of one-half of the thyroid body (thyroidectomy). It nray lie tied near its origin, where it lies alimg thi' inner border of tiie anterior scalene muscle, — i.e., between that musele and the internal jugular vein, or to the inner side of the carotid sheath as it enters the thyroid gland. It is seldom ligatured near its origin, where it may be secured through an incision similar to that made in ligature of the vertebral artery. To reach it just before it enters the thyroid body, where it lies on or slightly below the level of the cricoid cartilage of the larynx, the shoulders should be elevated and the neck extended, and an incision three inches long be made along the lower portion of the anterior border of the sterno-mastoid muscle. The skin, superficial fascia, and platysma myoides muscle are divided, avoiding the anterior external jugular vein ; the superficial layer of the deep fascia is also divided. The sterno-mastoid mu.scle and carotid sheath with its contents should be drawn outward, and the sterno-hyoid and sterno-thyroid muscles and tlivroid ])ody drawn inward. Locate tlie carotid tubercle behind the carotid sheath, and the artery will be felt pulsating just below and internal to it. Next divide the preverteljral fascia. The artery should then be tied near the carotid sheath, thus avoiding injury of the recurrent laryngeal nerve ; this nerve, however, is not in much danger, as in this location it lies behind and internal to the lateral lobe of tlie thyroid body. The inferior thyroid artery frequently divides behind the carotid sheath into two terminal branches of about equal size, which are separated by an interval of about one-fourth of an inch. Irregularities. — The inferior thyroid artery occasionally arises directly from the first portion of the subclavian artery ; it may, however, arise from the third portion near the outer border of the scalenus anticus muscle, or from the vertebral or common carotid artery. It may subdivide before it reaches tlie thyroid body, or it may arise as two separate arteries, one branch of it passing in front of and the other beliiml the carotid sheath. The artery maj^ be small or absent. The common carotid artery is tied for aneurysm or wounds of the internal or external carotid artery or their branches, to check malignant growths, and pre- paratory to the removal of tumors. It may be tied in any part of its course in the neck, which is indicated liy a line drawn from the sterno-clavicular articulation to a point midway between the angle of the lower jaw and the mastoid process of the temporal bone, the portion of this line below the level of the upper border of the thvroid cartilage indicating the course of the common carotid arterv. On the 180 SURGICAL ANATOMY. right side the common carotid artery arises as one of tlie two terminal branches of the innominate artery, which divides behind the upper border of the right sterno-clavicular articuUition ; on the left side, however, it arises within the chest from the arch of the aorta. On both sides the common carotid artery terminates opposite the upper border of the thyroid cartilage, where it divides into the external and internal carotid arteries. In front of tlie artery are the skin, superficial fascia, platysma myoides muscle, superficial layer of the deep fascia, inner border of the sterno-mastoid muscle, ante- rior jugular vein, sterno-hyoid muscle, sterno-thyroid muscle, lateral lobe of the thyroid gland, superior and middle thyroid veins, middle sterno-mastoid artery, omo-hyoid muscle, descendens hypoglossi nerve, ansa liypoglossi, and anterior wall of the sheath. To its outer side are the internal jugular vein and the pneumo- gastric nerve. On the right side the internal jugular vein at the root of tlie neck passes outward away from the artery, while on the left side it overlaps the artery and curves forward to empty into the left innominate vein. Behind and to its outer side is the pneumogastric nerve, and behind it are the posterior wall of its sheath, the sympathetic nerve, inferior tliyroid artery, recurrent laryngeal nerve, and the longus colli and rectus capitis anticus major muscles. To its inner side are the inner wall of its sheath, the trachea, esophagus, recurrent laryngeal nerve, lateral lobe of the thyroid gland, cricoid cartilage, thyroid cartilage, pharynx, superior thyroid artery, and external laryngeal branch of the superior laryngeal nerve. It is usually tied in the superior carotid triangle, — above the anterior belly of the omo-hyoid muscle, — where it is more superficial. In the inferior carotid tri- angle — below the anterior belly of the omo-hyoid muscle — the artery is deeper, being in this location covered by additional structures, the sterno-hyoid and sterno- thyi-oid muscles, and overlapped by the lateral lobe of the thyroid gland. The omo-hyoid muscle crosses the artery at the level of the cricoid cartilage, the middle thyroid vein crosses just above that muscle, and the superior thyroid vein and middle sterno-mastoid artery cross the artery higher in the .superior carotid triangle. In the operation through the superior ccmitiil triangle the patient should rest upon the back, with the shoulders elevated, the neck extended, and the face turned slightly to the opposite side. The superficial veins should be located, especially the vein which connects the submental veins with the anterior jugular vein and runs beneath the platysma myoides muscle parallel to and along the inner side of tlie anterior boi-dcr of the sterno-mastoid muscle. An incision three inches long sliould l)e made in the line of the artery, so that the center of the incision will be on a level with the cricoid cartilage. Skin, superficial fascia, platysma myoides muscle, superficial vessels and nerves, and the superficial layer of the dee]) fascia are divided, the communicating branch between the anterior jugular and sub- PLATE XL Superficial fascU Superficial layer of deep fascia Buccal br.of facia Supramaxillary br.of facial n, Inferior dental n. , Inferior dental a. ,Masseter m. Deep fascia Platysma myoides m. Superficial fascia Deep fascia Facial v. Facial a. Lower jaw .Platysma myoides m. r -Superficial layer of deep fascia Descendens hypoglosi^i n. rr,o-n-,astoid a. Superficial cervical nj Superficial descending br.of cervical plexus (n,) Anterior belly of omo-hyoid m. Sterno-mastoid nn. ' Incisions into carotid sheath and true arterial sheath Ansa hypoglossi (n.) Middle sterno-mastoirl a. I tXPOSURE OF (1) INFERIOR DENTAL NERVE; (2) FACIAL ARTERY; (3, 4) SPINAL ACCESSORY NERVt AND SUPERFICIAL BRANCHES OF CERVICAL PLEXUS; AND (5) COMMON CAROTID ARTERY IN SUPERIOR CAROTID TRIANGLE. 182 PLATt XLI, Hypoglossal n Occlp Superficial layer of deep fascia External jugular v Internal jugular v Sterno mastoid m Bifurcatior), of common carotid A External carotid a. Lingual a. Facial a. rnal carotid a. Facial Lingual V. f superior thyroid v. Superior thyroid a. Superior thyroid v. Superficial fascia Superficial layer of deep fascia Omo-hyoid m Platysma myoides m Sterno-mastoid m Br. of ans2 hypoglossi n Middle sterno-mastoid a Anterior jugular v. Sheath of sterno-thyroid m. Carotid sheath Thyroid body Common carotid a. and opening in true sheath (1) EXPOSURE OF EXTERNAL CAROTID AND INTERNAL CAROTID, AND OF THE SUPERIOR THYROID, LINGUAL, FACIAL, AND OCCIPITAL AT THEIR ORIGIN; AND v?) EXPOSURE OF COMMON CAROTID IN INFERIOR CAROTID IRIANCLE. 183 LK! AT/OX OF AIITERIES OF UFA I) AND NECK. 185 mental veins WAwix avdiilcil. Tlio sterno-mastoid must'lc .slioulil he ilisplaced out- wanl anil the omo-hyoid lunsele ilDunward, ami tlie })ulsations of the arterv are felt. Tlie middle sterno-mastoid arteiy and the superior and middle thyroid veins sliould he avoided, if possible, and the internal jugular vein and descendens hypo- glossi nerve should be avoided l)y opening the inner wall of the carotid sheafli. \\\ holding up tirst one edge of the opening in the slieath and then the other, the siieath can he gently separated from the artery with an aneurysm needle. The needle should he passed from without inward, threaded, and witlidrawn. To tie the connnon carotid artery in the inferior carotid Iriangle, the patient should be placed in the same position as for the higher ligation. The incision, which is about three inches in length, should be made along the anterior border of the sterno-mastoid muscle, beginning at the level of the cricoid caVtilage, and extending almost to the sterno-clavicular articulation. Skin, superficial fascia, platysma myoides muscle, and superficial vessels and nerves are divided. The anterior jugular vein and the vein which connects it with the facial or submental vein should be avoided. The superficial layer of the deep fascia is divided, and the sterno-mastoid muscle drawn outward, the sterno-hyoid and sterno-thyroid muscles inward. The sheath is opened on tlie inner side, and the needle passed from with- out inward. The structures which are to be avoided in the operation are the ante- rior jugular vein ; its tributary, which runs beneath the platysma myoides muscle parallel with the anterior border of the sterno-mastoid muscle ; the nerves from the ansa hypoglossi to the sterno-hyoid and sterno-thyroid muscles, the internal jugular vein, the inferior thyroid veins, the inferior thyroid artery, and the recurrent larj'ngeal nerve. On the left side the internal jugular vein overlaps the artery at the lower part of the neck and renders the operation more difficult. Collateral Circulation. — The collateral circulation, after ligation of the common carotid artery, is established by the anastomoses of the following arteries : with Proximal Side. Branches of the external carotid artery of the opposite side Vertebral artery of same side and opposite internal carotid artery with and vertebral arterv Inferior thyroid arterv, thyroidea ima artery (if present) Ascending cervical artery Superficial cervical artery with Princeps cervicis artery. Deep cervical artery Ascending cervical artery with Ascending pharyngeal artery. Vertebral artery with Occipital artery. Distal Side. Branches of the external carotid artery of the same side. Internal carotid arterv of the same side through circle of Willis. with Superior thyroid artery. 186 SURGICAL ANATOMY. The tissues supplied by the external carotid arterj' are chiefly nourislied through the anastomoses between the opposite branches of the two external carotid arteries, and the portion of the brain previously nourished by the internal carotid artery receives its blood supply through the two vertebral arteries and the opposite internal carotid artery. Irregularities. — The right common carotid artery, when the innominate artery is absent, may arise from the arch of the aorta separately or from a tnmk common to tlie two common carotid arteries. When it arises from a trunk com- mon to it and the left common carotid artery, it may cross in front of the trachea above the sternum. Owing to the variability in the level at whicli the innominate artery bifurcates, the right common carotid artery may arise higlier or lower than the upi)er margin of tlie right sterno-clavicular joint ; its origin is more frequently below that level than above it. The left common carotid artery varies chiefly in its origin fi'om the arch of the aorta. Its place of origin may extend into that of the innominate artery. When the right common carotid artery arises from the arch of the aorta, the two carotid arteries may arise from a common trunk. The left common carotid artery occa- sionally arises from a left innominate artery. Either of the common carotid arteries maj' bifurcate higher or lower than the upper border of the thyroid cartilage. The artery may bifurcate above the level of the hyoid bone, giving off some of the branches which should arise from the external carotid artery. It may not bifurcate, the external carotid or internal carotid artery being absent. The point of bifurcation may be as low as tlie root of the neck. The common carotid artery may be absent, the external carotid and internal carotid arteries arising from the innominate artery or the arch of the aorta. The conmion carotid artery niay give origin to the thyroidea ima, vertebral, inferior thyroid, or some of the branches of the external carotid artery. The pneumogastric nerve may lie in front of tlie common carotid artery. Tlie external carotid artery is ligatured after injury to tliis vessel or its liranclies, to check malignant growths, in cirsoid aneurysm of its branche.s, before removal of tlie parotid gland, and in various other conditions. The artery is usually tied lietween the points of origin of the lingual and superior thyroid arteries and in the superior carotid triangle, as it is more superficial here, and the distaiu'e from the bifurcation of the common carotid artery is sufficient to favor tiic formation of a clot. Its course is represented by that portion of tlie line of tlie common carotid artery whicli is above the level of tlii' u))pi'r border of the thyroid cartilage. In the superior carotid triangle below the posterior bell}' of the digastric muscle the external carotid artery is covered by skin, super- LIGATION OF ARTERIES OF HEAD AND NECK. 187 ficial fascia, platysma niyoides imisclc, superlk'ial layer of tlie deep fa^ieia, anterior lionler of tiie stenio-niastoid muscle, and the sheath of the vessels; it is crossed by the hypo-glossal nerve and lingual and laeial veins. Jligher in its course it is crossed by the stylo-hyoid and jiosterior belly of the digastric muscle, and enters the parotid gland. To its inner side are the hyoid bone, the pharynx, the superior laryngeal and glusso-pharyngeal nerves, part of the parotid gland, and the ranuis nf the Imver jaw. To its outer side, at its origin, is the internal carotid artery. IJehind it are the internal carotid arteiy, from which it is separated above by the stylo-glossus and stylo-pharyngeus muscles, the glosso-pharyngeal nerve, the pharyngeal branch of the pneumogastric nerve, the stylo-liyoid ligament, and p;irt of the parotid gland. The superior laryngeal nerve is also behind the arti'ry. The position of the patient should be the same as in ligature of the connnon carotid artery, the shoulders being elevated, the neck extemled, and the face turned slightly to the opposite side. The incision should exti'ud from the angle of the lower jaw downward along the anterior l)order of the sterno-niastoid nuiscle for about two and one-half inches, so that the greater cornu of the hyoid bone will be just above the center of the incision. The skin, su])erficial fascia, platysma myoides muscle, some cutaneous vessels and nerves, and the superficial layer of the deep fascia are divided. The sterno-mastnid muscle is drawn outward, and the greater cornu of tlie hyoid bone, the liypo-glossal nerve, and lingual and facial veins located. The sheath is opened, and the needle is passed from without inward. The needle should be kept close to the artery, tlius avoiding the superior laiyngeal nerve, which passes beneath the artery. Collateral Circulation. — The collateral circulation, after ligature of the external carotid artery, is established by the anastomoses between the branches of this artery and the corresponding branches of the opposite external cai-otid artery. Irregularities. — The external carotid artery may be absent, the branches of that artery arising from the common carotid artery, which continues upward as the internal carotid artery. It may be a short trunk or arise at a higher or lower level than noi'mally. Two or more of its branches— as the suijcrior thyroid, lingual and facial arterie.s — may arise from it by a connnon trunk. Some of its lower branches may arise from the common carotid artery. Occasionally it gives origin to additional branches — viz., the superior laryngeal and middle .sterno- mastoid branches of the superior thyroid artery, the ascending palatine and tonsillar branches of the facial artery, the superior sterno-mastoid branch of the occipital artery, and the transverse facial branch oi the su]ierficial temporal artery. The superior thyroid artery is tied prej)aratory to removal of one-half of the thyroid body, and may be ligatured to arrest the growth of a goiter. It arises from the external carotid artery just below the greater cornu of the hyoid hone, and runs 188 SURGICAL ANATOMY. forward and then downward and forward along the inner side of the carotid sheath. Its upper portion is superficial, its lower jjortion l)eing more deeply situated between the larynx and the carotid sheath. The superior laryngeal nerve lies beneath the upper portion of the artery, and its external laryngeal branch runs parallel with the lower part of the vessel. The artery may be tied near its origin and above its hyoid branch, but is preferably ligatured between the origins of the superior laryngeal and middle sterno-mastoid branches. The patient is placed in the same position as for ligature of the external carotid artery, and an incision two inches long should be made along the anterior border of the sterno-mastoid muscle. The center of the incision should be on a level with the upper border of the thyroid cartilage. Skin, superficial fascia, pla- tysma myoides muscle, and superficial layer of the deep fascia are divided. The sterno-ma.stoid muscle is drawn outward, and the superior thyroid arter}' seen run- ning downward along the inner side of the carotid sheath. The artery should be traced from its origin and tied above the origin of the middle sterno-mastoid artery, avoiding the superior thyroid vein. The vein which connects the facial or sub- mental vein with the anterior jugular vein and runs beneath the platysma myoides muscle parallel with the anterior margin of the sterno-mastoid muscle should also be avoided. The needle is preferably passed away from the superior thyroid vein, which usually runs on the lower side of the artery and may form a plexus. Irregularities of the superior thyroid artery and of the other branches of the external carotid artery are not of much surgical importance. The superior thyroid artery may be double, or it may be unusually small, the other thyroid arteries being larger than normal. It may arise from the common carotid artery or a trunk common to it and the lingual artery, or a trunk common to the supe- rior thyroid, lingual, and facial arteries. The hyoid, superior laryngeal, and middle sterno-mastoid branches may arise from the external carotid artery. The superior laryngeal artery may be unusually large, occasionally passing through a foramen in the thyroid cartilage, or it may pass along the thyroid cartilage and turn inward under the lower margin of that cartilage. The crico-thyroid artery may be unusually large, and may send a branch downward over the crico-thyroid membrane to the isthmus of the thyroid body. Such an abnormal branch would be divided in laryngotomy and perhaps in high tracheotomy. For this reason it is advisable to thoroughly expose the crico-thyroid membrane before incising it, as the entrance of blood into the larynx might cause broncho-pneumonia. Tlu' lingual artery is mo.st frequently ligatured preparatory to removal of the tongue. It is also tied to control licmorrhage from it or its liranches in injuries and advanced carcinoma of the tongue, to check the growth of advanced carci- noma of tile tongue, and in macroglossia. It arises from the external carotid LIGATIOX OF ARTERIES OF HEAD ASD NECK. . ISO artery, opposite the greater coriiu of tlu' hyoid hone, and its course, as elsewhere described, is divided into three portions : The first portion extends from the origin of the artery to the outer border of the hyo-glossus muscle. It ascends to reach the upper border of the greater cornu of the hyoid bune, and then runs just above and parallel with that cornu. Tiiis is the most superficial portion of the artery. It is covered by skin, superficial fascia, platysma myoides muscle, and superficial layer of the deep fascia, and is crossed by tlie liypo-glossal nerve, lingual vein, and digastric and stylo-hyoid mu.scles. This jiortion of the vessel rests upon the middle constrictor muscle of the pharynx and the superior larj'ngeal nerve. The second portion runs along the upper l)order of the hyoid bone beneath the hyo-glossus nuiscle, lingual vein, hypo-glossal nerve, diga.stric and stylo-hyoid muscles, submaxillary gland, superficial layer of the deep fa.scia, platysma myoides muscle, and superficial fascia and skin. It rests here upon the middle constrictor muscles of the pharynx and the genio-hyo-glossus muscle. This portion is the point of election in ligation of the artery. The third portion ascends between tlie hyo-glossus and genio-hyo-glossus muscles, pierces the latter muscle, and runs between it and the lingualis muscle in the under surface of the tongue as far as the tip of that organ. To ligature the lingual artery in its second jiortion, or point of election, the patient should be placed in the same position as for ligature of the common and external carotid arteries, and the lower jaw drawn upward. The incision extends from the anterior border of the sterno-mastoid muscle forward along the upper border of the greater cornu of the hyoid bone. The skin, superficial fascia, platysma myoides muscle, branches of the facial and anterior jugular veins, and the superficial layer of the deep fascia are divided. The submaxillary gland is displaced and held well upward on the lower jaw, and the process of deep fa.scia beneath the gland divided. The tendon and bellies of the diga.stric muscle, the stylo-hyoid muscle, the hypo-glo.s.sal nerve, the lingual vein (which is just below the nerve), the injdo-hyoid and the hyo-glossus muscle, will be exposed. The stylo-hyoid muscle and the tendon of the digastric muscle are drawn down- ward, the lingual vein and hj-po-glossal nerve upward, and an incLsion one-half of an inch long should be carefully made through the hyo-glo.ssus muscle just al)ove the hyoid Ixme. If the incision through the hyo-glos.sus mu.scle is accurately made, the artery will project into the wound. The aneurvsm needle is passed around the artery, and may include the vena; comites. The submaxillar}' gland should not be injured, as this accident would probably give rise to a salivary fistula. To avoid the danger of opening the pharynx when incising the hj'o- 190 . SURGICAL ANATOMY. glossus muscle care is required. Instead of dividing tlie hyo-glossus muscle, the artery may be ligatured immediately before it passes under the outer border of tliat muscle. The first jwrtion of the lingual artery is reached through an incision one inch long, carried from the sterno-mastoid muscle forward along tlie upper border of the greater cornu of the hyoid bone. The position of the patient should be the same as that for the foregoing operation. Skin, superficial fascia, platysma myoides nuiscle, and sui^erficial layer of the deep fascia are divided. The .submaxillary gland is displaced upward, and the process of deep fascia beneath the gland divided. The lingual vein and hypo-glo.ssal nerve are exposed and drawn upward, and the artery secured as it passes under the posterior margin of the hyo-glo.ssus muscle. This operation is more difficult than ligature of the .second portion of the vessel ; tliis is due to the fiiet that the lingual vein, hypo-glossal nerve, .stylo-hyoid muscle, and posterior belly of the diga.stric mu.scle lie in front of the artery. This portion of the artery may be secured at its origin through an incision two inches long, made along the anterior border of the sterno-mastoid muscle. The center of the incision .should be opposite the greater cornu of the hyoid bone. The location of the external carotid ai'tery is ascertained, as described under ligatui-e of that vessel, and the origin of the lingual artery located opposite the greater cornu of the hyoid bone. The hypo-glossal nerve and lingual and facial veins must be avoided. Irregularities. — The most common irregularities of the lingual artery are the following : It may arise from a trunk common to it and the facial artery, or from a trunk common to the superior tliyroid, Hngual, and facial arteries. It may pierce the hyo-glossus muscle. Occasionally it is given off as a branch of tlie fVicial or internal maxillary artery. Its sublingual branch may arise from the facial artery, and the hyoid branch may be absent. The facial artery may be secured at its origin or as it passes over the lower border of the lower jaw at the anterior inferior angle of the masseter muscle. To ligature the facial artery at its origin, wliich is just above tliat of the lingual artery, an incision should be made similar to that for ligation of the external carotid artery, except that the center of the incision should be just above the gi'eater cornu of the hyoid bone. The facial and lingual veins, anterior division of the temporo- maxillary vein, and hypo-glossal nerve should be avoided. To tie the artery as it turns over the lower border of the lower jaw, an incision one incli long should be made below and parallel with tiiis l>order of the jaw, so that the resulting scar will not bo ]ironiiii(iit. The skin, superficial fascia, platysma myoides muscle, and superlicial layer of the deep fascia arc diviili-d. As tlie facial vein is behind the artery, the needle should be passed from l)eliind forward. Irregularity. — The irregularity of the facial artery wliich is of importance PLATE XLII. Occipital a. SternoiTiastoid m. Superficial fascia Deep fascia' Splenius capitis m Venae comites Splenius capitis m. Princeps cervicis a. Sterno-mastoid m EXPOSURE OF OCCIPITAL ARTERY FOR LIGATION. 1U2 PLATE Temporal a. Temporal v. Auriculo-temporal n. Superficial fascia EXPOSURE OF AURICULO-TEMPORAL NERVE AND TEMPORAL ARTERY. S- n-13 193 4 LIGATION OF ARTERIES OF HEAD AND NECK. !<):> is tlio following : It may teniiinate as the sul)niental artvrv, its area of distri- Itution in the face being siipiiliiMl hy the nasal hraneh of the ophthalmic, the transverse facial, or the internal maxillary artt-ry. The occipital artery is ligatured for cirsoid aneurysm. It may be tied at its origin, or as it passes through the occipital region. To tie it at its origin the shoulders should be elevated, the neck well extended, and an incision made along the upper part of the anterior border of the sterno-mastoid muscle. The origin of the arter}' will be found by tracing backward over the external carotid arteiy the hypo-glossal nerve, which winds I'nim bt'hind forward over that jiortioii of the vessel. In the occipital region the artery may be secured through an incision carried oblicjuely backward and slightly upward from the tip of the mastoid process. The structures divided in the occipital region are the skin, superficial fascia, superficial nerves and vessels, superficial layer of the deep fascia, a portion of the sterno-mastoid muscle, posterior process of the deep fascia (prevertebral fascia), and the splenius capitis muscle. The artery may be readily found in this region, at a point midway between the mastoid process and the external occipital protuberance. Irregularities. — The irregularities of the occipital artery which are of im- portance are the following : It may arise from the internal carotid artery or the ascending cervical branch of the inferior thyroid artery ; it may cross over, instead of under, tlie upper portion of the sterno-mastoid muscle ; it may give origin to the posterior auricular or ascending pharyngeal artery. Irregularities of the ascending pharj-ngeal, posterior auricular, superficial temporal, and internal maxillary arteries are not of much surgical imj^ortance. The superficial temporal artery, like the occipital, is ligatured in injuries and cirsoid aneurysm. The artery usually Ijifurcates into the anterior and posterior temporal one and one-half to two inches above the zygoma, but it frequently divides at a lower level. The artery may be felt pulsating just in front of the ]iinna of the ear, where it crosses the posterior root of the zvgoma ; this is the point at which it should be tied. The incision should be vertical, about one inch in k'ngth, and be made over the vessel in front of the pinna. The .structures ilivided are the skin, superficial fascia, and deep fascia. The superficial temporal vein lies behind the artery and overlaps it, and the auriculo-temporal nen'e emerges from beneath the artery and vein, and then runs behind the vein. The temporal branches of the facial nerve cross the artery and vein in the jjarotid gland. The needle should be passed from behind forward. The internal carotid artery is rarely ligatured, Init may be tied after injury of the vessel and for traumatic aneurysm. The line for this vessel is the same as that for the common carotid artery. Its only accessible and superficial portion 196 . SURGICAL ANATOMY. is at its origin, and is about one inch in length. The internal carotid artery begins at the bifurcation of the common carotid artery, which is opposite the upper bor- der of the tiiyroid cartilage. At first it lies external to and on the same plane as tlie external carotid artery, but it gradually passes beneath the latter vessel. In front of it in this location are the skin, superficial fascia, platysraa myoides mus- cle, superficial layer of the deep fascia, anterior border of the sterno-mastoid muscle, and the wall of the carotid sheath ; behind it are the pneumogastric nerve, prevertebral fascia, superior sympathetic ganglion, and rectus capitis anticus major muscle ; to the outer side are the pneumogastric nerve and internal jugular vein ; and to the inner side are the external carotid artery, ascending pharj-ngeal artery, and pharynx. The patient should be placed in the same position as for liga- ture of the common carotid artery. An incision three inches long is made over the anterior border of the sterno-mastoid muscle, the center of the incision being slightly above the level of the upper border of the thyroid cartilage. Skin, sui^erficial fascia, platysma myoides mu.scle, and superficial layer of the deep fascia are divided. The sterno-mastoid muscle is drawn outward, the posterior belly of the digastric muscle upward, the external carotid artery inward, and the internal carotid artery outward. The anterior wall of the sheath of the artery should be carefully opened, and the needle passed from witliout inward, away from the internal jugular vein and pneumogastric nerve. In many cases the facial and lingual veins cross the internal carotid artery to empty into the internal jugular vein. Collateral Circulation. — The i'ollateral circulation is established by the anastomosis of the vertebral arteries and opposite internal carotid with the liga- tured artery through the circle of Willis. Irregularities. — The irregularities of the internal caroti EXPOSURE OF SUPRAORBITAL ARTERY AND NERVE. 197 OPERATIONS UPON NERVES OF HEAD AND NECK. V.)'.) exposed, the supra-tn-hital vessels beiiij;- on its outer side. Tiir palpebral faseia is divided, the orhilal fal dcpri'sscd, ami the nerve traced into tln^ orhii as far us possible, so that the i'ronhd nerve may be reached and divided just bei'orc it bil'ur- eates into the supra-orbital and supra-trochlcar nerves. About an inch of the .-:u{ira -orbital nerve is resected. The supra-orbital vessels may be injured. The supra-iirliital arlciy may be liii-ated through the same incision. • The infra-orbital nerve may be resected thriiui;h an incisitm three-fourths of an inch long, made about one-fourth to three-eighths of an inch below, and paralkd with, the infra-orbital margin, so that its center will lie over the infra-orbital foramen, which is situated in a line drawn from the supra-orbital notch to the second bicuspid tooth of the upper jaw, and between one-fourth and three-eighths of an ini'h below the infra-orbital margin. The skin, superficial fascia, orbicularis jialpebrarum muscle, and levator labii superioris mu.scle are divided, the nerve is drawn out of the foramen, and as much as possible resected. The superior maxillary nerve is resected in the si)heno-maxillary fossa by way of the antrum of Highmore, or through an incision at the side of the face. These operations are described in volume i, page 503. The Gasserian ganglion is removed through an o.steo-plastic resection of the temporal region, or by way of the ptery go-maxillary region. (See Vol. i, page 595.) The inferior maxillary nerve is exposed at its exit from the foramen ovale. The retlected flap is scjuare, its attached margin being below. Two vertical incisions are made, parallel with the margins of the ramus of the lower jaw, and extend from the level of the upper margin of the zygoma to half way down the ramus ; the upper extremities of the incisions are connected by a transverse incision. The skin and superficial fascia are divided, the zygoma is sawed at each end, the temporal fascia and the masseteric fascia are divided, the zygoma and the mas- . seter muscle are displaced downward, and the masseteric vessels and nerve are severed. Care is rec^uired to avoid injuring Stenson's duct and some of the large branches of the facial nerve which are at the attached margin of the flap. The coronoid process of the lower jaw is divided and reflected n|iward with the temporal muscle ; and the upper head of the external pterygoid nnisdc is sepa- rated from the pteiygoid ridge of the sphenoid bone and displaced downward. The nerve can then be exposed at the foramen ovale and divided with scissors. The small meningeal artery is nece.ssarily divided with the nerve. The foramen ovale is situated about one-fourth of an inch in front of the spine of the .sphenoid bone, just l)ehind the base of the external pterygoid i)late, and in a transverse line passing tln-ough the emincntia articularis of the temporal bone. This operation is hardly justifiable on account of the number of important tissues injured, the resulting paralysis of the muscles of mastication and of the mylo-hyoid muscle 200 SURGICAL ANATOMY. and anterior belly of the digastric mnsclc, tlie partial loss of power in movinji; the lower jaw, and the dangers of infection and sni)pnration in so inaccessible a region as the ptervgo-niaxillary space. The inferior dental nerve may be resected at the mental foramen, in the inferior dental canal, or before it enters that canal. It is preferably resected before it enters the inferior dental canal, in (H'der that all the dental and gingival fibers of the nerve can be included. This portion of the nerve can be reached by an incision through the cheek or through tlie mucous membrane of the mouth. The external incision is preferable because a.sepsis is an impossibility in wounds of the mouth, the external method is more easily performed, and the incision can be so located that the .scar will not be prominent. The incision in the external method is angular and made along the posterior hurder of the ramus to the angle of the lower jaw, and thence forward along the lower border of the lower jaw, each limb of the incision being about one inch in length. Only the skin and super- ficial fascia are divided in the first stage of the operation. Next divide the mas- .seteric fascia and the platysma myoides muscle, exercising care to avoid injuring the buccal and supra-maxillary branches of the facial nerve and the parotid gland. The lower limb of the incision should not extend far enough forward to divide the facial artery or vein. The lower portion of the masseter muscle is separated from the ramus of the lower jaw with the periosteal elevator and the knife, and displaced upward. A small trephine is applied to the ramus midway between its anterior and posterior borders, and just above the level of the alveolar margin of the lower jaw. The trephine first divides the upper and thinner portion of the circle of bone ; the remainder of the incision thrDugli tiie bone must be completed witli the chisel and elevator, so that the inferior dental vessels will not lie injured. The inferior dental vessels and nerve are detected lying upon the internal lateral ligament of the lower jaw. The nerve is separated from the vessels, drawn out with a blunt hook, and as much of it as possible resected. In neurectomy of the inferior dental nerve thrLiugli the mouth, the upper teeth are widely separated from tlie lower with a gag, and a vertical incision about an incli long is maile through the mucous membrane along the inner margin of the anterior border of the ramus of the lower jaw. Tlie anterior margin of the ramus is exposed, and the mucous membrane is separated from the ramus with a small periosteal elevator. The lingual nerve is seen, the separation is extended a short distance rurthcr liackward, and the s])ine of lione (spine of Spix) just below tlie iiil'cri(ir dental foramen is located with tlie finger. Tliis spine gives attachment to tlie internal lateral ligament of tlie lower jaw; this ligament hides from view the inferior dental vessels and nerve which lie between it and the ramus of the lower jaw. The internal lateral ligament is cautiously divided with long, slender scis- PLATE XLV, Mucous membrane Lingual n. EXPOSURE OF LINGUAL NERVE, 202 PLATE XLVI. Posterior auricular n. Posterior auricular a. Facial n. Deep fascia Superficial fascia * V ^ Mastoid process Sterno-mastoid m Posterior belly of digastric m. EXPOSURE OF FACIAL NERVE. 203 OPERATIONS UPON NERVES OF HEAD AND NECK. 205 sors, ami tlic iiil'riior ilcntal vessels ami iutvo are exposcMl at tlicir entrance into the interii)r ilrnlal canal. The ncrvo and vessels are gently drawn lorwanl witli u small blunt hook and traced upward for about a half inch above their point of entrance into the inferior dental canal. Here the nerve and vessels are not in so close contact and can be separated. The nerve is i.solated from the vessels, and about one-l'ourth or one-half of an inch removed, the upper end of the segment being divided tirst because of the fact that the upper part of the nerve retracts after being divided. If the nerve and vessels are traced too high, the internal maxillary artery is endangered. The wound in the mucous membrane is not closed. The lingual (gustatory) nerve is divided or a portion of it excised for pain- ful conditions of the tongue, as advanced cancer of that organ. The nerve may be expo.sed by merely cutting through the mucous membrane of the floor of the mouth near the side of the tongue, and opposite the second molar tooth. The nerve may also be exposed by dividing the mucous membrane about one-half of an inch below and behind the last molar tooth, where the nerve can readily be felt. The auriculo-temporal nerve is exposed where it first lies in relation with the superficial temporal vessels over the posterior root of the zygoma and in front of the pinna of the ear. The incision is the same as that made for ligation of the superficial temporal artery. The nerve is found just to the outer side of the super- ficial temporal vessels. The facial nerve is stretched for twitching of the muscles of expression, asso- ciated with more or less pain (tic convulsif). The nerve is secured near the stylo- mastoid foramen, as it lies superficial to the styloid process and above the posterior belly of the digastric muscle. In this location tlie trunk of the nerve is found before it gives off the stylo- hyoid and digastric branches, and before it bifurcates into its two divisions. The posterior auricular nerve arises from it close to the stylo-mastoid foramen. The incision begins behind the pinna of the ear, opposite the external auditory meatus, and is carried Ijcliind the lobule of the ear downward and forward to the angle of the lower jaw. A transverse incision may also be made behind the lobule. The skin, superficial fascia, superficial layer of the deep fi^scia, and branches of the auricularis magnus nerve are divided. The flaps which have been made are now dissected from the j^arotid gland, sterno-mastoid muscle, and mastoid process, the posterior auricular nerve, vein, and artery being avoided. The parotid gland is separated from the mastoid process, and the trunk of the nerve is found above the posterior belly of the digastric muscle, lying upon the styloid process. The nerve is stretched by lifting it with a blunt hook. The spinal accessory nerve is stretched or divided for spasmodic wryneck. Division or excision of a j)ortion of the nerve offers better results. The nerve is 206 SURGICAL ANATOMY. secured at the anterior or at the posterior border of the sterno-mastoid muscle. When it is exposed behind tlie sterno-mastoid muscle, it should he traced upward and divided above its sterno-mastoid branches. In its course downward from the jugular foramen the nerve runs beneath the internal jugular vein, the occipital artery and posterior belly of the digastric muscle, and enters the under surface of the sterno-mastoid muscle abnut midway between its two borders and about two inches from the tip of the mastoid process. It emerges from the muscle at about the middle of its posterior liorder. Between the posterior belly of the digastric muscle and the point where it enters the sterno-mastoid muscle it is accompanied by the superior sterno-mastoid artery. Before exposing the nerve at the anterior border of the sterno-mastoid muscle the patient is placed on his back, with the shoulders raised and the neck extended. Tlie incision begins at the anterior border of the mastoid process, and is carried downward for two and one-half or three inches along the anterior margin of the sterno-mastoid muscle. The skin, suj^erficial fascia, platysma myoides muscle, a branch of the auricularis magnus nerve, and the deep ftiscia are divided, the external jugular vein being avoided. The sterno-mastoid muscle is drawn outM'ard, and the nerve, with its accompanying sterno-mastoid artery, can be felt just below the prominent transverse process of the atlas, lying upon the levator anguli scapulae muscle. Before exposing the spinal accessory nerve at the posterior border of the sterno-mastoid muscle the shoulders are elevated, the face is turned to the opposite side, and the neck is flexed laterally toward the opposite shoulder. The incision is made along the posterior border of the sterno-mastoid muscle, is two inches in length, and its center is at the middle of that border of the muscle. The skin, superficial fascia, platysma myoides muscle, and the superficial layer of the deep fascia are divided. The small occipital nerve is easily found as it runs along the upper one-half of the posterior border of the sterno-mastoid muscle. This nerve is traced downward to the spinal accessory nerve, with which it forms a loop. The spinal acces.sory nerve is then traced beneath or through the deeper jiortion of the sterno-mastoid muscle and divided. The superficial branches of the cervical plexus may be exposed through the same incision as that made at the posterior border of the sterno-mastoid muscle for the spinal accessory nerve. The auricularis magnus nerve runs from the middle of the posterior border of the sterno-mastoid muscle toward the j^iima. Tlie occipitalis minor nerve lies between the superficial layer of the deep fascia and its posterior process (prevertebral fascia), and just behind tlic u|iper one-half of the posterior margin of the sterno-mastoid muscle. The superficial cervical nerve emerges from under the sterno-mastoid muscle at the middle of its posterior PLATE XLVIl Stemo-mastoid m. Superficial layer of deep fascia Platysma myoides m. Superficial fascia Descending branches of cervical plexus (n.) Prevertebral fascia Scalenus anticus m. Transversalis colli a. Platysma myoides External jugular v Scalenus medius m.- ;? Posterior jugular v Posterior belly omohyoid m Upper trunk of brachial plexus Middle trunk of brachial plexus Lower trunk of brachial plexus Subclavian a EXPOSURE OF BRACHIAL PLEXUS OF NERVES. 208 I THE MOUTH. 209 honlcr, turns dowiiwnnl alis, which divides into the supra-sternal, supra-tdavicular, and supra-acroniial nerves, is found running along the posterior border of the sterno-mastoid muscle just below the middle of that margin, and usually passes between the sterno-mastoid muscle and the external jugular vein. TIk' brachial plexus may be stretched in the neck external to the scalenus anticus muscle. It onerges from between the scalenus anticus and scalenus medius muscles, and converges toward the apex of the axilla. The patient is placed on the back, with the shoulders elevated, the neck extended, and the fiico turned to the opposite side. The incision begins al)out one-half of an inch above the middle of the clavicle. It is carried directly upward ibr about three inches, and parallel with the posterior margin of the sterno- mastoid muscle. The skin, superficial fascia, and platy.sma myoides muscle are divided. The external jugular vein, which lies to the inner side of the incision, should be located, and it may be nccessaiy to divide the posterior external jugular or transverse cervical and supra-scapular veins between ligatures. The superficial layer of the deep fascia is next divided. The posterior belly of the omo-hyoid muscle is drawn upward, the transversalis colli artery and the cords of the jilexus and the position of the outer border of the scalenus anticus muscle are located with the finger. The posterior process of the deep fascia (pre- vertebral fascia) is divided a short distance external to the scalenus anticus muscle, avoiding the nerve to the subclavius muscle, which runs along the outer border of the scalenus anticus muscle, and the transversalis colli arterj', which runs across the upper part of the jilexus. The prevertebral fascia is reflected outward. The upper and miildle cervical trunks of the plexus are found above the subclavian artery, whereas the lower trunk is overlapped by the upper margin of that artery. THE MOUTH. The student should now examine the mouth, the pharynx, the larynx, and the nose. These are attached to the anterior portion of the skull which has been divided previous to the dissection of the prevertebral muscles. The mouth is situated at the commencement of the alimentarv canal. It contains the organs of mastication, those of the sense of taste, some of the organs of speech, and it acts as a resonating cavity. The buccal cavity (cavity of the S— 11-14 210 SURGICAL ANATOMY. mouth) is divided into two parts liy the teeth and alveolar processes — viz., the ves- tibule and the mouth jaroper. The Vestibule is situated between the lips and cheeks externally, and the teeth and gums internally. The walls of the vestibule, except when it is dis- tended, are in contact. In front it opens upon tlie face at the l>uccal orifice, and beiiind the last molar teeth it conununicatesi with the mouth jtroper, even when the teeth are in contact, so that in tetanus or during treatment of fractures of the lower jaw a patient may be fed liquids througli a tube passed from the back part of the vestibule into the mouth proj^er. Under these circumstances a preferable method of feeding may be through a catheter introduced through the nose. The Lips are composed of the skin, superficial fascia, orbicularis oris muscle and the muscles inserted around it, areolar tissue, and mucous membrane. The first three laj^ers of the lips — skin, superficial fascia, and muscular tissue — have been described -with the face. The margins of the lips are covered with dry, red mucous membrane, which is continuous with the skin, and contains numerous vascular i^ajjill* and touch corpuscles. Internalh'', the mucous membrane is retlected from the upper and lower lips upon the gums, and in the median line forms two filds — the frtcnum labii superioris and frtenum laljii inferioris. Along the line of junction of the skin and mucous membrane "fever blister," or herpes labialis, is very common. Through cicatricial contraction after burns of the lips and cheeks the buccal orifice may be much distorted. The deformity can be lessened, if not corrected, by plastic operation. The areolar tissue, or submucous layer, contains the coronary vessels, branches of the infra-orbital and mental nerves, and the labial glands. The coronary vessels completelj' encircle the buccal orifice near the free margin of the li}>s, lying immediatelj' sujjerficial to the mucous membrane in the submucous layer. The labial glands are situated around the orifice of the mouth, in the sub- nnicous layer of the lips. The_y are small lobulated bodies, about the size of a small pea, and their ducts open into the mouth. They secrete a mucous fluid. When the ducts of these glands become occluded, mucous retention cysts develop. Between the lips is the buccal orifice, which extends between the angles of the mouth. In harelip operations and after excision of a large segment of the lip in removing an epithelioma, the mobility and elasticity of the lips, particularly of the lower liji, allow approximation of the edges of the wound. The lymphatics fi-om the median imrtinn of (be lower lip pass to a lymphatic gland situated just above the body of the hyoid bone ; those from the lateral ]wr- tions pass to the submaxillary lyni|i]iatic glands, into which the lymjihatics of the U]i]>er lip also empty. PLATE Superior m Superior tu Mio'JIe tur Hyoid bone Mylo-hyoid Thyro- edge Ventricle of Thyroid cart aphra^ma sellae vum sellae Spenoidal cell Middle meatus Naso-pharynx Orifice of Eustachian tube Hard palate Soft palate Uvula Anterior pillar of fauces -Tonsil in recess of fauces Oro-pharynx Epiglottis (cut edge) Aryteno-epiglottidean fold '. t Latyngo-pharynx uprarimal portion of larynx False vocal cord True vocal cord nfrarimal portion of larynx Cricoid cartilar^e (cut) Ring of trachea i VERTICAL SEGTIOK OF MOUTH, PHARYNX, LARYNX, 212 ^D NOSE. THE MOUTH. 213 The operation which is frequently perfonnehalic glands near the angle of the lower jaw, and into the superior deep cervical lym- phatic glands. Kelatioxs. — Externally, the tonsil is in relation with the superior con- strictor muscle of the pharynx and the pharyngeal aponeurosis, which separate it from the internal carotid and the ascending pharj'ngeal artery ; internally, with the mueons membrane of the mouth and pharynx. Tonsillitis. — The tonsils are frequently affected by inflammation. In follic- ular tonsillitis the crypts especially are involved, and their secretion is inspissated, forming yellowish-white pilugs which resemble diphtheric false membrane, and give the throat the appearance of "ulcerated sore throat." In phlegnionuus or jiurulent tonsillitis (cjuinsy), when the affection is bilateral, the tonsils may almost meet in the median line. These tonsillar abscesses should be incised with a bis- toury, guarded to avoid injuring the tongue. The knife should be directed back- ward and inward, and the incision be made toward the median line to avoid injuring tlie internal carotid artery, which lies just external to the gland. Hypertrophied tonsils can not be felt externally below the angles of the lower jaw, for the reason that the pharyngeal aponeurosis and the superior constrictor muscles of the pharynx prevent the tonsils from projecting outward. The masses present in these locations are enlarged lymphatic glands which receive lymphatic vessels from the tonsils. Hypertrophied tonsils project beyond the pillars of the fliuces, and cause considerable annoyance through their inter- ference with respiration and with the resonance of the voice. Hypertrophied tonsils should be amputated with a tonsillotome, or removed by dissection. Exaggerated prominence of the anterior pillars of the fauces may render these operations quite difficult. The relation which the tonsil bears to the internal carotid and ascending pharyngeal arteries should be borne in mind in either of these operations. The ascending pharyngeal artery runs upon the external surface of the supe- rior constrictor muscle of the pharynx, opposite the tonsil, and in operations upon the tonsil or in wounds of that organ is in more danger of being injured than is the internal carotid artery, which is placed further back. S— 11—15 22G SURGICAL ANATOMY. Malignant growths of the tonsil are not infrequent, and are best renioveitaI bone. The constrictor muscles are arranged so that the inferior overlaps the middle, and the middle overlaps the superior. The wferior constrictor muscle of the pharynx arises from the posterior part of the side of the cricoid cartilage behind the crico-thyroid muscle, from the inferior cornu, the oblique line, and the superior l)onler of the ala of the thyroid cartilage. Its fibers diverge as they pass backward around the pharynx, to be inserted into the median raphe. The lower fillers are almost horizontal, and are continuous with the muscular coat of the esophagus. The upper fibers ascend obliquely over the lower portion of the middle constrictor muscle, to be inserted into the raphe higher up. Passing beneath or through the lower border of the inferior constrictor muscle at its origin are the recurrent laryngeal nerve and the inferior laryngeal brancli of the inferior tliyroid artery on their way to the larynx. The middle constrictor muscle of the jihariphr has a narrow origin from the stylo- hyoid ligament, the lesser cornu of the liynid Ijone, and the entire length of the upper surface of the greater cornu of the hyoid bone. Its fibers diverge as they pass to the back of the pharynx, to reach tlie median raphe. The lower fibers are almost horizontal, and pasg beneath the upper part of the inferior constrictor muscle. The upper fibers pass oblicjucly upward over the lower part of the superior constrictor muscle, to reach the raphe near the base of the skull. Some of its tendinous fibers continue upward to the pharyngeal spine on the basilar process of the occipital bone. In the interval between the origins of the middle and inferior constrictor muscles, the infernal laryngeal branch of the superior laryngeal nerve and the sujierior laryngeal artery pierce the thyro-hyoid membrane. Near the upper margin of tlie middle constrictor muscle runs tlie glosso-pliaryngeal nerve, and passing beneath that margin is the stylo-pharyngeus muscle. Its origin is covered by the hyo- glossus muscle and the lingual artery, wiiicli lies between the hyo-glossus and the middle constrictor muscle. Dissection. — To expose the origin of tlie superior constrictor muscle it is necessary to remove the internal pterygoid muscle. In removing tiie origin of that muscle from the pterygoid fos.sa preserve the tensor palati muscle, wliicli lies between the internal pterygoid muscle and llic internal pterygoid plate. Tlie superior constrictor muscle is a thin, pale, ([uadrilateral muscle. It arises PLATE LI. Ophthalmic a iternal carotid a Sympathetic n Internal carotid a Superior cervica sympathetic ganglion Ascending pharyngeal a External carotid a Common carotid a Lateral lobe of thyroid body Inferior thyroid a Recurrent laryngeal n. Trachea Middle constrictor m. Pharyngeal aponeurosis and sinus of Morgagni Buccinator m. -Pterygo-maxillary ligament Superior constrictor m. Raphe Stylo-pharyngeus m. Tip of greater cornu of hyoid bone Inferior constrictor m. Circular muscular fibres of esophagus Longitudinal muscular fibres of esophagus CONSTRICTOR MUSCLES OF PHARYNX. 229 THE I'lIAUYNX. 231 from till' lowiT uiu'-tliinl nf the [HLsterior ImnK'r of the iutrrnal ])ltTy,t;x)iil iilate, froiu the lianiuhir pnicess uf tliat phiti', the iiterv.s^cvuiaxiHary liganu'ut, tlio postoriiii' part of the iiiylo-hyoid riilnv of the lower jaw, ami the side of the base of the toiii;-ue. its lihers pass haekwai'il to he inserted into the median raphe. The lower fibers are overlapped hy the middle constrictor muscle. The upper fibers curve uiiward, and have a tendinous attachment to the pliaryuii'eal s[>ine on the basilar ]iroeess of the oeeipiilal bone. The upper margin is erescentii', and situated some distance from the base of the .skull, k'aving a semilunar interval — the sinus of Morgagni. Tlie floor of the sinun (if Margarinl is formed by the pharj'ugeal aponeurosis. The upper border of the superior constrictor muscle of the pharynx is in relation with the levator l>alati nmsele and the Eustachian tube. Tlie superior constrictor muscle with the pharyngeal ajioueurosis separate the ascending pharyngeal and internal carotid artei'ies from the tonsil. Nerve Suri'i.v. — The constrictor muscles of the pharynx derive their nerve supply from the jiharyngeal plexus. The interior constrictor muscle receives additional branches from the external and recurrent larjmgeal nerves. Tetanus often presents its first symptom as spasm of those muscles of masti- cation which elevate the lower jaw, — viz., the masseter, temporal and internal pterygoid muscles, — and of the eonstrii'tor muscles of tlie pharynx. Consequently, the patient can not open the mouth, and deglutition, or swallowing, is difficult or causes choking sensations. Spasm of the constrictor muscles of the pharynx and difficult deglutition are also in'ominent symptoms of hydrophobia. The Pharyngeal Plexus of Nerves is found chiefly upon the middle con- strictor muscle. It is formed by the pharyngeal branchi's of the pneumogastric, external laryngeal, and glosso-pharyngeal nerves, anil of the superior cervical sympathetic ganglion. It supplies the muscular and other coats of the pharynx. The Pterygo-maxillary Ligament is a fibrous raphe between the buccinator and superior constrictor nuiscles, and extends from the lower extremity of the internal jiterygoid plate to the jDOsterior end of the mylo-hyoid ridge or internal oblique line of the lower jaw. The Pharyngeal Aponeurosis, the fibrous coat of the i>harynx, is dense and strong where the muscular coat is absent, — viz., at the sinuses of Morgagni and in the triangular intervals between the origins of the constrictor muscles, — and be- comes delicate and fades away below. It holds tlie pharynx open by means of its attachment to the I)asilar process of the occipital bone, the cartilages in the middle lacerated foramina, tlie a])ices of the j>cti'ous portions of the temjioral bones, the posterior l)orders of the internal pterygoid plates, the greater cornua of the hyoid bone, and the ])osterior Ijorders of the alte of the thyroid cartilage. 23-2 SURGICAL ANATOMY. The Mucous Coat, or mucous monibrane, lining the jiharynx is continuous with that of the Eustaeliian tubes, nasal cavities, mouth, larynx, and esophagus. It contains racemose mucous glands and scattered lymphoid follicles. Because of its A'ascularity, inflammation of this membrane, which is known as pharyngitis or sore throat, frequently occurs. Through the continuity of the mucous mem- brane of the nose and larynx the catarrhal process may extend to the mucous membrane of those cavities. Dissection. — Divide the posterior wall of the jiharynx in the median line, and detach it from the base of the skull as far as the lateral wall. Tlion turn the two flaps outward, to study the interior of the pharynx. Beneath the petrous portion of the temporal bone the cavity of the pharj'nx extends outward, forming a pouch — the pharyngeal recess. The Pharyngeal Tonsil of Luschka is a collection of lymphoid tissue in the posterior wall of the pharynx, near its junction with the roof The Pharyngeal Bursa is a small diverticulum in the posterior wall of the pharynx, below the occipital bone ; it is most conspicuous in the fetus and in infants. Hypertrophy of the Pharyngeal Tonsil is the source of adenoid growths in the naso-pharynx. Obstruction of the i:)Osterior narcs, loss of nasal resonance in the voice, and mouth breathing result. Extension of the hypertrophic process into the Eustachian tubes causes obstruction of those tubes, tinnitus aurium, or peculiar sounds in the ears, and deafnes.s. Post-pharyngeal Abscess, usually resulting from caries of the upper cervical vertebrfe or suppuration of the post-pharyngeal lymphatic gland, may bulge into the pharynx and cause difficulty in deglutition or respiration. Post-phaiyngeal abscesses, and those arising in the ptervgo-maxillary region and temporal fossa, may rupture into the pharynx. There are seven Openings into the pharynx : The two posterior nares, two Eustachian tubes, mouth, larynx, and esophagus. The two posterior nares (choana?) are at the highest point of the anterior wall of the pharynx. They are separated from each other by the posterior margin of the septum of the nose. Through them can be seen the middle and inferior tur- binated bones. When a mirror is placed innnediatcly behind the soft palate, tlie superior turbinated bones can also be seen. The trumpet-shaped orifices of the Eustachian tubes iir(> in the lateral walls of the |)harynx, at about the level of the ini'crior liirliinateil bones. It .should l)e noticed that a Eustachian catheter carried through the inferior meatus to the posterior wall of the piiarynx. rotated outwai'd, and di'awn forward along the lateral wall of the jdiarynx until it ])asses over the elevation at the posterior mar- PLATE Pharyngeal tonsil Pharyngeal bursa Orifice of Eustachian tube W'^'\' Posterior wall of pharynx Lymphoid nodules PHARYNGEAL TONSIL AND BURSA. 233 PLATE Nasal septum Posterior naris Uvula Circumvallate papillae Foramen caecum Lymphoid tissue at base of tongus Cuneiform cartilage Corniculum laryngis Interarytenoid fold ^m^^s^m^ Middle tuibinated bene Inferior turbinated bone Inferior constrictor m Soft palate Posterior pillar of fauces Tonsil Epiglottis Aryteno-epiglottidean fold ^ Sinus pyriformis Mucous membrane of pharynx reflected around larynx Esophagus Trachea INTERIOR OF PHARYNX. 236 THE rilARYSX. 237 o-in of tlio Eustachian orifice, will readily slip into the Eustachian tube when puslied backward again. Frdin their (iriliee.s the Eustachian tubes are directed backward, outward, and slightly ujiwanl, opening into the tympanic cavity at its anteri(_ir wall. The inner portion of the Eu.-^taehiau tube is cartilaginous on the up[)er and inner sides, and llbrous below. The outer jxirtion of the Eustachian tulu' has bony walls, and begins in the receding angle between the s(iuamous and jietrous portions of the temporal bone. The isthmus of the fauces, or posterior opening of the mouth, is situated im- mediately below the posterior nares and soft palate. Through the isthmus some of the sli'uctures of the mouth can be examined li'om behind. The pillars of the fauces, the tonsils, situated in the recesses of the fauces, and the base of the tongue are more satisfactorily seen through the isthmus of the fauces than through the buccal orifice. The base of the tongue holds a vertical position, and overhangs the epiglottis. Between the tongue and the epiglottis are the three glosso-epiglottidcan folds and the two glosso-epiglottidean pouches. The superior aperture of the larynx is situated l)elow the base of the tongue. It is a large, triangular-shaped opening, its wider portion being directed forward. It slopes oblicjuely downward and backward from the upper extremity of the epiglottis. It is bounded in front by the epiglottis, behind by the interarytenoid fold of mucous membrane, and on each side by the aryteno-epiglottidean fold and the tips of the arytenoid cartilages. On each siundant in its upper surface, although there is some adenoid tissue in its under surface. Blood Supply. — From the dorsalis lingure and the ascending pharyngeal artery, the ascending palatine branch of the facial arterj', and the jjosterior pala- tine branch of the internal maxillary artery. The veins correspond to the arteries. The lymphatics empty into the glands at the angle of the jaw. Nerve Supply. — From Meckel's ganglion, the glosso-pharyngeal nerve, the pharyngeal plexus of nerves, and the otic ganglion. The tensor palati muscle is supplied by a branch from the otic ganglion. The levator palati, palato-glossus, palato-pharyngeus, and azygos uvuhc muscles are i)robab]y supplied by branches from the pharyngeal plexus, which are derived from the spinal accessory nerve. Clefts of the Soft Palate may exist independently of clefts of the hard palate. They are widened by the tensor palati, levator palati, palato-glossus, and palato-pharyngeus muscles. These clefts give rise to difficulty in deglutition, because they allow food to pass into the naso-pliarynx and nose. Before closing the cleft, the aponeuroses of these muscles are divided to ])revent them from caus- ing tension \x\)(m the sutures. The aponeuroses of the tensor palati and levator palati muscles may be divided by one incision. A slender bistoury, with its cutting edge directed forward and upward, is inserted into the soft palate slightly in front of and close' to tlie inner side of the liannilar ]irocess of the internal Ijterygoid jilate of the sphenoid bone, until it projects through the superior surface TUK LAUYSX. 247 of tlie soft palate. As the knife is pushed iiiiwanl it cuts the tensor palati aponeu- rosis. The bistoury is thru carried upward, ibrwanl, and inward, cutting the superior surface of tiie sott palate for a distance sufficient to allow severance of the levator pahiti aponeurosis. The palato-glossus and |iahito-pharvngeus muscles can he divided 1)V a shallow incision across each of the pillars of the fauces. Tiie attachment of the palatine aponeurosis to the posterior margin of the hard palate may also cause dilficulty in aiiproximating the freshened margins of tlie cleft, and should be divided as far as neees,sary. The success of the operation depends chiefly upon the relief of tension upon the sutures. Paralysis of the Muscles of the Soft Palate and Pharynx may occur during convalescence from diphtheria. As a result, tiiere is dilHculty in swallowing and regurgitation of food through the nose. THE LARYNX. The larynx is a membrano-cartilaginous, box-like organ. It is the organ of voice, assists in protecting the respiratory tract from the entrance of foreign bodies during deglutition, and closes the respiratory tract, so that the chest can be made firm tluring gi'eat muscular effort. It is situated at the upper portion of tlie respiratory tract, above the trachea and in front of the lower jiortion of the pharynx. Anteriorly, it is covered 1)}' skin, superficial and deep fascia;, two thin layers of muscular tissue, and, occasionally, a jsrocess of the middle lobe of the thyroid gland. The superficial stratum of muscular tissue is composed of the sterno- Iryoid and omo-hyoid muscles ; the deep stratum, of the sterno-thyroid and tlij-ro- hyoid muscles. The great vessels lie on each side of the larynx in the groove between the larynx and the sterno-mastoid muscle. It is suspended from the skull by the stylo-hyoid ligament, the muscles attached to the superior surface of the hyoid bone, and the stylo-pharvngeus and palato-pharyngeus nniscles, which are inserted into the posterior borders of the alse of the thyroid cartilage. It is lined internally by mucous membrane which is continuous above with that lining the pharynx, and below with that of the trachea. It consists of three single cartilages and three i)airs of cartilages united by membranes, ligaments, and muscles. The three single cartilages are the thyroid, cricoid, and epiglottis ; the paired ones are the arytenoid, cornicula laryngis, and cuneiform. The larynx is larger in all its dimensions in the male than in tlie female. The Superior Aperture of the Larynx inclines obli(|uely downward and backward. It is bounded in front by the epiglottis; fiehind, by the interarj'tenoid 248 SURGICAL ANATOMY. fold of mucous membrane ; and at the sides, by the aryteno-epiglottidean folds and the tips of the arytenoid cartilages. The aryteno-epiglottidean folds extend from the sides of the epiglottis to the summits of the arytenoid cartilages. They are composed of two layers of mucous membrane, between which are a snpi)()rting layer of connective tissue ; the cor- nicula laryngis, which rest upon the summits of the arytenoid cartilages ; the cunei- form cartilages, which lie in front of the arytenoid cartilages ; and the aryteno- epiglottidean mu.scles. In viewing the larynx from above, the corniculum laryngis and cuneiform cartilage appear as two small swellings in the ar^yteno-epiglottidean fold. In these folds there is much loose sul>nuieous tissue, which is the chief site of the swelling in edema of the larynx. Tliis swelling may be so extensive as to interfere seriously with the entrance of air into tlie larynx, and laryngotomy, tracheotomy, or intuliation may become neces.sar3'. The sinus pyriformis, which is between the aryteno-c]iiglottidean fold and tlie ala of the thyroid cartilage, the three glosso-epiglottidean folds, and the valleculee, between the epiglottis and the base of tlie tongue, have been previously described. Two pairs of folds may be seen stretching across the cavity of the larynx. The upper pair is formed by the false vocal cords, and the lower pair by the true cords, which are more closely approximated. A depression — the ventricle of the larynx — exists between the true and false cords. The interval between the true vocal cords is the chink of the glottis, or rima glottidis. The true vocal cords divide the larynx into a supra-i'imal and an infra-rinial jiortion. The Supra-rimal Portion of the larynx extends from the superior aperture to the true vocal cords. It is wide and triangular aliove, and becomes narrow below. The Infra-rimal Portion is compre.s.sed laterally above, and becomes circular below, where it is surrounded by the cricoid cartilage and leads into the trachea. In laryngotomy the knife enters this portion of the larynx and is directed down- ward and backward to avoid the vocal cords. Dissection. — Clean the anterior portion of the external surface of the larynx, entirely removing the attachments of the sterno-hyoid, omo-hyoid, and th}-ro- hyoid muscles from the hyoid bone, those of the thyro-hyoid and sterno-thyroid muscles from the thyroid cartilage, and the attachments of the inferior constrictor muscles of tlic jiharynx froni the thyroid and cricoid cartilages. ■ Avuid injuring the su|icri(ir laryngeal artery and tlie internal liranch of the superinr laryngeal nerve, which pierce the thyro-hyoid membrane ; the externa! laryngeal nerve, whicli sup]ilies the inferior constrictor and the crico-thyroid muscle ; the crico- thyroid artery, which crosses the crico-thyroid membrane ; and tlie recurrent laryngeal nerve and inferior laryngeal artery, which i)ass to the larynx behind PLATE LVI! Vocal process of arytenoid cartilage True vocal cord Sinus pyriformis Interarytenoid fold Posterior wall of pharynx Corniculum laryngis Cuneiforna cartilage Aryteno-eplglottidean fold False vocal cord Ventricle of larynx Posterior pillar of fauces Tonsil Anterior pillar of fauces Lateral glosso-epio-lottidean fold '^^ Median glosso-epiglottidean fold Adenoid tissue at base of tongue Foramen caecum Circumvallate papillae Fungiform papillae SUPERIOR APERIURE OF LARYNX. 250 PLATE LVIIl Greater cornu of hyoid bo Lesser cornu of hyoid bo Lateral portion of tliyro-hyoid membran Internal laryngeal Superior laryngeal a Thyroid cartilage Crico-thyroid membran Crico-thyroid m. Lateral lobe of thyroid gland Trachea Isthmus of thyroid gland Epiglottis Hyoid bone ntral portion of thyro-hyoid embrane Inferior constrictor m. of pharynx Superior thyroid a. rico-thyroid a. evatop glandulae thyroidcae 1. ricoid cartilage thyroid veins LARYNX AND CRICO-THYROID MUSCLE. 251 PLATE LIX, Epiglottis Cartilage tri+icea Internal laryngeal branch of superior laryngeal n Superior laryngeal a Superior cornu of thyroid cartil. Ala of thyroid cartilage Oblique line of thyroid cartilage Inferior border of thyroid cartilage Inferior cornu of ihyroid cartilage Cricoid cartilage Recurrent laryngeal n Greater cornu of hyoid bone Thyro hyoid ligament Lesser cornu of hyoid bone Body of hyoid bone Lateral portion of thyro hyo'd mcnr.brane Central portion of thyro-hyoid membrane Superior border of thyroid cariilage tncisura thyroideae Angle of thyroid cartilage . Lateral portion of crico-thyro.d membrane Central portion of crico-thyroid membrane Capsular ligament of crico-thyroid articulation ANTERIOR VIEW OF LARYNX, INCLUDING CRICO-THYROID MEMBRANES. 254 THE LAh'VXX. 255 the cric'O-thyrditl articulation. This disHectioii more thorouglily exposes tlie tliyro- liyoid iiu'iiihraiu', thyroid c-artihigv, crieo-tliyroid muscles, crico-thyroid momliranc, and cricoid cartilajic The Thyro-hyoid Membrane, which is lart>cly coniposcd of clastic lihcrs, extends tVnni the u|i|i(.t Imnli r oi' the thyiciid carlila^c to (lie posterior sujicrior border of the hyoid ixiiic. Its central purtion is thick and strong, and its lateral portions are thin and pierced by the supt'rior laryngeal arteries and internal laryngeal nerves on their way to the interior of the larynx. The thyro-hyoid bursa intervenes between the thyro-hyoid membrane and the posterior surftice of the liyoid bone, and may be enlarged aners ]iass around the apex of tlie arytenoid cartilage, and join the aryteno- epiglottideus muscle to form a sphincter for the superior aperture of the larynx. The transverse portion is thicker, and connects the posterior concave surfaces of the arytenoid cartilages. Nerve Supply. — From the recurrent and sujierior laryngeal nerves. 11—17 PLATE LX, Laryngeal surface of epiglottis Muscular process of arytenoid cartilage Cricoid cartilage Arytenoepiglottidean fold Aryteno-epiglottideus m. Arytenoideus m. ■Thyroid cartilage Crico-arytenoideus posticus m. 1 Recurrent laryngeal n. I MUSCLES OF LARYNX-POSTERIOR VIEW. 23S PLATE LXl. Epiglottis- Aryteno-epiglottidean fold- Aryteno-epiglottideus m. — Thyro-epiglottideus m.- Thyroid cartilage Thyro-arytenoideus m: Crico-thyrold membrane- Cf'coid cartilage Superior cornu of thyroid cartilage Arytenoideous m. Muscular process of arytenoid cartilag Crico-arytenoideus lateralis m. Crico-atyleno'deus posticus m. Facet for articulation with inferior cornu of thyroid cartilage MUSCLES OF LARYNX-LATERAL VIEW. 259 THE LARYXX. 2(11 Action. — The arvtenoideus muscle draws the arytenoid cartilages together and approximates the vocal cords. The Crico-arytenoideus Lateralis Muscle arises from the upper border of the cricoid cartihige, in liunl of the crieo-urytenoid articulation. It is inserted into the anterior and inferior aspects of the external angle of the arytenoid cartilage. It is covered by tlie tiiyroid cartilage and the crico-thyroid muscle, and rests upctn the lateral portidu of the crico-thyroid nienil)rane. Its upper border, near its termination, blends with the thyro-arytenoid muscle. Nerve Supply. — From the recurrent laryngeal nerve. Action. — It pulls the arytenoid cartilage forward, relaxing the vocal cords, and rotates that cartilage inward, approximating the cords and closing the rima glottidis. The Thyro-arylenoideus Muscle is a quadrilateral band of muscular fillers which is divided into a superior and an inferior portion. The superior portion is broad and thin, and is situated above the level of the A'ocal cords, external to the ventricle of the larynx and the laryngeal pouch. It arises from the lower two- thirds of the inner surface of the ala, near the angle of the thyroid cartilage, and is inserted into the anterior surface and external angle of the arytenoid cartilage. The inferior portion is closely attached to the true vocal cord. It arises from the ala, near the angle of the thyroid cartilage, external to the attachment of the true vocal cord, and is inserted into the anterior angle (\'ocal process) and the adjacent portion of the anterior surface of the arytenoid cartilage. Some of its deeper fibers {ary^^ocalis of Ludwig) are attached to the vocal cord at several points. Nerve Supply. — From the recurrent laryngeal nerve. Action. — The thyro-arytenoid muscles relax the true vocal cords by drawing the arytenoid cartilages forward, and approximate them by drawing the vocal processes downward and inward. The ary-vocalis can make a portion of the true cord tense while the remainder is relaxed. The Thyro-epiglottideus Muscle is composed of a few of the uppermost fibers of the thyro-arytenoideus muscle, which turn upward, external to the laryngeal pouch, to be attached to the side of the epiglottis. Nerve Supply. — From the recurrent laryngeal nerve. Action. — It depresses the epiglottis. The Aryteno-epiglottideus Muscle is situated in the aryteno-epiglottidean fold. It arises from the apex and anterior border of the arytenoid cartilage, above the false vocal cord. Its upper fibers are inserted into the mucous membrane at the margin of the aryteno-epiglottidean fold, and its lower fibers are inserted into the side of the epiglottis. It is joined by .some of the fibers of the oblique portion of the arj-tenoideus muscle, which pass around the apex of the arytenoid cartilage. 262 SURGICAL ANATOiMY. Nerve Supply. — From the recurrent laryngeal nerve. Action. — It pulls the epiglottis backward and compresses the laryngeal pouch, and with the assistance of the arytenoideus muscle acts as a sphincter of the .superior apei'ture of the larynx. The muscles just described — viz., the two crico-thyroidei, two crico-arytenoidei postici, one arytenoideus, two crico-arytenoidei laterales, two thyro-arytenoidei, two thyro-epiglottidei, and two aryteno-epiglottidei — are the intrinsic muscles of the larynx. The extrinsic muscles of the larynx — viz., the sterno-thyroid, thyro-hyoid, stylo-pharyngei, and palato-pliar^'ngei — have been described with the neck and pharynx. These muscles are assisted by all the muscles which elevate or depress the hyoid bone and larynx or hold the hyoid bone firm. In' Laryngismus Stridulus, or laryngeal asthma, there occurs spasm of the muscles of the larynx. This condition occurs most frecj[uently in children, is usually due to reflected irritation, as after eating indigestible food, and ma}"- be caused by irritation of the nerve centers in the medulla oblongata. In adults it may be caused by pressure upon the recurrent laryngeal nerve by aneurysms, malignant growths of the esophagus or posterior mediastinal glands, or enlarge- ment of the thyroid body. It may also l)e produced liy irritation from foreign bodies in the larynx or lower part of the pharynx. Nerve Supply of the Larynx. — From the superior laryngeal and recurrent laryngeal branches of the pneumogastric nerve. The Superior Laryngeal Nerve divides into the external and internal laryn- geal nerves. The external laryngeal nerve passes downward with the superior thyroid artery, and sup[)lies the crico-thyroid muscle. The internal laryngeal nerve pierces the thyro-hyoid membrane with the superior laryngeal artery, passes downward and backward, ramifies upon the intrinsic muscles in the lateral wall of the larynx, and supplies the mucous membrane, sending a branch to the ary- tenoideus muscle. The internal laryngeal nerve is the sensory nerve of the larynx. The Recurrent Laryngeal Nerve is the motor nerve of the larynx, and reaches it behind the crico-thyroid articulation, where it divides into an anterior and a posterior branch. The posterioi- branch supplies the arytenoideus muscle and the crico-arytenoideus posticus muscle, and communicates with the internal laryngeal bi'ancli of the superior laryngeal nerve ; the anterior branch sui)})lies all the other intrinsic mu.scles except the crico-thyroid muscle. Paralysis of the Right Side of the Larynx may be caused by pressure upon the right recurrent laryngeal nerve, i)roduced by aneury.sm of the first portion of the right subclavian artery or lower portion of the right common carotid artery. PLATE LXII. IGreater cornu of hyoid bone. Thyro-hyold ligament IThyro-hyoid membrane. ^Superior cornu of thyroid cartilage I Aryteno-epiglottideus m. Arytenoideus m. Posterior border of thyroid cartilage Posterior crico-arytenoid m. Crico-thyroid articulation- Cartilago trlticea Internal laryngeal n. Superior laryngeal a. Cricoid cartilage Recurrent laryngeal n. Inferior laryngeal a. NERVES AND ARTERIES OF LARYNX. 263 II 4* •* THE LARYNX. '2G5 enlargement of tlie tliyinid Ixxly, malignant disease of the esophagus, and cicatrices at the api'X '■'( tlie rii;iit iilcura, as in phllii.sis. Paralysis of the Left Side of the Larynx may be caused by pressure upon till' left recurrent laryngeal nerve, produced by aneurysm of the arch of the aorta and lower portied, the stem of the Y being attached to the cricoid cartilage and the two limbs to the summits of the cornicula laryngis. The cornicula laryngis and tanu'iform cartilages, on larj'ngoscopic examina- tion, appear as two whitish swellings in the i)Osterior extremity of each aryteno- epiglottidean fold. The arytenoid cartilages are two irregularly pyramidal bodies, which rest upon the upper border of the posterior portion of the cricoid cartilage. Their greater portion is composed of hyaline cartilage ; the remainder, their apices, being yellow elastic cartilage. Each has an apex, a base, three sides, three bor- ders, ami three angles. The apex is directed ujiward, backward, and inwai'd, and supports the cornieulum laryngis. The base is concave, and presents on its inner side a facet for articulation with the cricoid cartilage. The three sides are an internal, a posterior, and an antero-external or anterior surface. The internal surface is directed toward the corresponding surface of the 02)po- site arytenoid cartilage, and is covered by mucous membrane. The posterior surface is concave, and gives attachment to the arytenoideus muscle. The antero-external or anterior surface is rough and irregular. It gives attach- ment to the thyro-arytenoideus muscle and tlie superior thyro-arytenoid ligament, which supports the mucous memlirane of the false vocal cord. The three borders are the internal, external, and anterior. The internal hunJer is directed inward and backward ; the external border slopes downward and outward ti.i the external angle; the anterior border slopes downward and forward to the anterior angle. The three angles are the internal, external, and anterior. The internal angle is situated at the postero-internal angle of the base. It gives attachment to the transverse or crico-arytenoid ligament. The external angle or muscular process is located at the external angle of tlie base. It gives attachment anteriorly to the lateral crico-arytenoid muscle, and posteriorly to the posterior crico-arytenoid muscle. The anterior angle or vocal process, situ- ated at the anterior angle of the l)ase. is long and pointed, and gives attachment to the true vocal cord or inferior thyro-arytenoid ligament. 27G SURGICAL ANATOMY. The hyaline cartilages of the larynx — namely, tlie thyroid, cricoid, aryte- noid, and cartilage triticea — frequently undergo ossification. When any of the cartilages of the larynx are fractured, the patient should be placed on his back, prohibited from talking, and fed through the rectum ; it may be necessary to practise intubation, laryngotomy, or tracheotomy. The Joints of the Larynx are the crico-thyroid and crico-arytenoid. The crico-thyroid joints arc formed by the articulation of the inferior cornua of the thyroid cartilage with the cricoid cartilage. They are lined by synovial membrane, and have capsular ligaments wliich are stronger posteriorly. Their movements are gliding of the cricoid cartilage ujiward and backward, and rotatory around a transverse axis. The crico-arytenoid joints are formed l>y the articulation of the cricoid carti- lage with the bases of the arytenoid cartilages. They have a capsular, a posterior crico-arytenoid, and a transverse or crico-arytenoid ligament ; and each has a syno- vial membrane. The capsular ligament is loose and allows free movement. The posterior crico-arytenoid ligament arrests the forward movement of the arytenoid cartilage. The transverse or crico-arytenoid ligament connects the upper border of the cricoid cartilage with the internal angles of the arytenoid cartilages. The crico-arytenoid joints permit of the arytenoid cartilages gliding inward or outward or rotating around a vertical axis. These movements permit the vocal processes to rotate inward and the arytenoid cartilages to be drawn together, closing the rima glottidis, as in phonation ; or they allow the vocal processes to rotate outward and the arytenoid cartilages to be separated, thus opening the rima glottidis as in res- piration. The Ligaments of the Larynx not associated with the joints are the thyro- hyoid and crico-th3a'oid membranes ; the thyro-hyoid ligaments, which have been described ; the superior thyro-arytenoid ligaments, described with the false vocal cords ; and the inferior thj^ro-arytenoid ligaments, described as the true vocal cords. In Laryngoscopic Examination the patient should sit at a higher level than the physician ; his tongue should be drawn foi'ward so that the base of that organ will not hang backward over the epiglottis and superior aperture of the larj'nx ; his head should be thrown backward so that the reflection of the interior of the larynx, instead of the image of the base of the tongue, will be seen. When the mirror has been introduced into the oro-pharynx, its handle must usually be depressed. The epiglottis will be seen in its u])per ]iart; the arytenoid cartilages, cartilages of Santorini and Wrisberg, in its lower part ; the fiilse vocal cords, ven- tricles, and true vocal cords, on their corresponding sides ; and the anterior wall of the trachea and, occasionallv, its bifurcation mav be seen. The true vocal cords PLATE LXV. / Prominence produced by sterno mastoid m. Common line of incision for laryngotomy, high tracheotomy and low tracheotomy Ridge over clavicle Supraclavicular fossa Segment of line locating incision in laryngotomy Segment of line locating incision in high tracheotomy _Segment of line locating incision in low tracheotomy Suprasternal fossa Fossa supraclavicularis minor SURFACE MARKS OF NECK AND LINES UP INCISIONS FOR LARYNCOTOMY 278 ^D TRACHEOTOMY. PLATE LXVI, Superficial layer of deep fascia Superficial f. Ski Cricoid cartilage Pre'.racheal fascia Sterno-hyoid m. Thyroid cartilage geal lymphatic gland •thyroid a. co-thyroid membrane ision into crico-thyroid membrane Sterno-hyoid m. Pretracheal fascia Incision into trachearl Isthmus of thyroid body 1 Cricoid cartilage \ Two divisions of superficial layer of deep fascia I fasci Supe Pretracheal fascia Trachea Incision into trachea Isthmus of thyroid body Two-division of superficial l.-^yer of deep fascia ' HIGH TRACHEOTOMY. LARYNGOTOMY. 279 LOW TRAGHEOTOMY, THE LAliyyX. 281 appear us wliitc hamls more nearly approximated than the false cords. In acute laryngitis tiie inu- vixal conls are of a pinkish color, and the remainder of the larynx is rrd and swollen. This swelling, or edema, of the glottis is produced by a serous inHltratimi intn the suhimicous areolar tissue ; and if present to a marked degree, is best treated by .scarification ; it may, however, necessitate intubation, laryngotomy, or tracheotomy. The Hyoid Bone is an important adjunct to the larynx. It prevents collapse of the pharynx over the sujierior aperture of the larynx, and from it the larynx is suspendeken Ijy muscular action. The Ijod}' of the bone is rarely frac- tured, one of the greater cornua usually being fractured. The Movements of the Larynx oi masse are in but two direction.? — upward and downward. The most marked movements are performed during deglutition, prior to which the larynx, as well as the pharynx, is drawn upward. By this means closure of the superior aperture of the larynx is facilitated, and elevation of the pharynx aids the constrictor muscles of the pharynx to grasp the morsel of food. The larynx is elevated by the following muscles : The digastric, the stylo- hyoid, the mylo-hyoid, the genio-hj'oid, the lower portion of the geniodiyo-glossus, the stylo-pharyngeus, and the palato-pharyngeus. It is depressed by the sterno- hyoid, the sterno-thyroid, and the omo-hyoid muscles. Laryngotomy is performed through the crico-th3'roid membrane. The shoulders are elevated by a jjillow, the head and neck are extended, a firm support is placed under the neck, and the face is made to look directly forward so that the relations of the structures in the median line of the neck may not be distorted. The thyroid and cricoid cartilages and the crico-thyroid space are outlined, the larynx is gently steadied with the thumb and fingers of one hand, and an inci- sion one and one-half inches long is made in the median line over the lower jiart of the thyroid cartilage, the crico-thyroid membrane, and the cricoid cartilage. The skin, the superficial fascia, and the superficial layer of the deep fascia are divided ; the sterno-hyoid and sterno-thyroid muscles are separated from the corresponding muscles of the opposite side ; the pretracheal fascia is divided ; and the central jwr- tion of the crico-thyroid membrane is divided transverselj' along the upper border of the cricoid cartilage. By dividing the lowest portion of the membrane the 282 SURGICAL AS ATOMY. crico-thj'roid arteries and the true vocal cords are avoided, and if the knife is directed downward and backward, the vocal cords are in less danger. Excision of the Larynx is sometimes performed for removal of malignant disease of tliat organ ; but tlie results of the operation are so discouraging that a palliative tracheotomy is usually preferred. The Trachea is directly continuous with the lower jiortion of the larynx, so that the larynx appears to be the upper extremity of the trachea modified for the performance of certain special functions. The trachea varies between four and one-half and five inclies in length and three-fourths of an inch and one inch in width. On transverse section it is shaped like a l)ar horseshoe, the indentation being posteriorly for tlie acconnnodation of the esophagus. The trachea is com- posed of cartilaginous rings, which are connected by fibrous membrane. The rings are horseshoe-shaped, with the open end posteriorly ; this interval is filled by the fibro-elastic membrane, which yields to pressure of bodies passing through the esophagus, thus providing additional space during deglutition. The trachea con- tains from sixteen to twenty of these rings, seven or eight of which are above the upper margin of the sternum. Wlien tlie head and neck are in the long axis of the body, about two inches of tlie trachea are above the sternum, and by full extension of the head and neck this distance may be increased to three inches. The trachea is cjuite superficial at its upper exti'emity, but rapidh' becomes deeply situated as it descends ; this is one of the reasons for preferring high tracheotomy. Relations of the Cervical Portion of the Trachea. — In front are the skin ; the superficial fascia; the superficial layer of tlie deep fascia, which is here composed of two layers ; a communicating branch between the anterior jugular veins, situated just above the sternum ; the sterno-hyoid and sterno-thyroid mus- cles ; the isthmus of the thyroid bodj' ; the inferior thyroid veins or thyroid plexus of veins ; occasionally, the thymus gland or the remains of that gland ; the pre- tracheal fascia, and the thyroidea ima artery when present. Occasionally, a high innominate artery or left innominate vein may l)e in front of the trachea at the root of the neck. Behind the cervical portion of the trachea is the esophagus. On each side of it are the lateral lobes of the th3'roid bod}', the recurrent larjm- geal nerves, the terminal portions of tlie inferior thyroid arteries, and the carotid sheaths inclosing the CDiiiiiioii carotid arteries, interiuil jugular veins, and pneumo- gastric nerves. The trachea will be more completely described under the section on the Chest. Tracheotomy. — The windpipe may be opened either aboA'e or below the isthmus of the thyroid gland ; the former procedure being known as high, the latter as low, tracheotomy. High tracheotomy is the easier of the two operations, because the first part of the trachea is less deeply jilaced and is somewhat larger THE LARYXX. 283 ami less mobilo, boinji, thcrcfoix', more accesssible than the part just abovt- the stiTiiuiii. Furthermore, the inferior thyroid veins, lying upon the trachea below the isthnuis, the oeeasional presence of" a thyroidea inia artery, and in infants the upper part of the thynnis gland, add to the ditticulties of the low operation. It is also to be remembered thai the iiniDmiuate artery or the left iumiminate vein may cross the trachea hiyher than usual and might he eiicuuiitercd in the low opera- tion. For the performance of the operation the head is well extended and so held by an assistant that the median line of the face will be in line with the median line of the neck. A firm cjdindric cushion or a large bottle is so placed under the back of the neck as to render its anterior region prominent. Tlic parts are steadied with the lingers and thuml) of one hand. The various landmarks, such as the pomum Adami and the cricoid cartilage, are recognized by palpation. The incision extends from about the lower border of the thyroid cartilage downward for two and a half inches in the median line. It is made from below upward, and divides skin and superficial fascia. The anterior jugular veins, which lie alongside of the median line, may now appear, and should be avoided by cutting between them and drawing them aside. The two layers of the superficial layer of the deep cervical fascia are then divided either upon a director or with the free hand. The interval between the flat pretracheal muscles is recognized, and the wound deep- ened by " blunt dissection " ; the director or the handle of the knife being used to slit down the soft parts in the median line until the pretracheal f;iscia is reached. The pretracheal fascia is incised and the tracheal rings ai'e fully exposed, the director or handle of the knee being again used in order to avoid hemorrhage. The isthmus of the thyroid gland is depressed, if need be, to gain additional space. Hemorrhage having been checked and the tracheal rings fully exposed, the trachea is held steady with a tenaculum and a sharp narrow-bladed knife, with its cutting edge directed upward, is thrust into the windpipe and two or three rings divided from below upwanl. The edges of the tracheal wound are tlu^n held apart with a dilator, hooks, or a loop of silk jiassed through each side. False membrane, if present, is withdraAvn, and the tracheal tube is inserted. xVfter opening the windpipe it will usually l_)e noticed that respiration is much slower, owing to the fiict that plenty of air is admitted ; whereas prior to the operation the breathing was Imrried, on account of the obstruction. It is important during the operation that the trachea be kept exactlj- in the median line, otherwise it may be opened on one side, or, from being careles.sly drawn to one side by the assistant, it may be missed altogether, and the operator, as has occurred, may expose the vertebral column before the error is recognized. 284 SURGICAL ANATOMY. It is also essential to thoroughly expose the rings of the trachea by clearing away the pretracheal fascia ; such exposure prevents the mistake of introducing the tracheal tube under that fascia, instead of into the windjjipe, thereby increasing the respiratory difficult}'. In children the cricoid cartilage is sometimes divided in addition to the tracheal rings, thus converting the operation into a larj^ngo-tracheotomy. In the low operation the same general rules are observed as in the high operation ; the incision extends from the top of the sternum to the cricoid carti- lage. After division of the skin and fascia^ the wound is deepened by blunt dissection, for there is here, of course, more danger of hemorrhage than in the previously described operation. The inferior thyroid veins, or thyroid plexus of veins, which lie upon the j^i'etracheal fascia, should be displaced, and the trachea thoroughly exposed, the forefinger being passed into the wound from time to time as the wound is deepened, in order to ascertain the relations of the tissues, recognize abnormal vessels, and feel the tracheal rings. THE NOSE. The Nose is the uppermost portion of the respiratory tract. It contains the special organs of the sense of smell, and removes particles of dust from and warms and moistens the inhaled air ; therefore, M^hen the nasal passages are occluded, disease of the lower i^ortion of the respiratory tract is more likely to occur. It may be divided into the nose proper and the nasal cavities or fossae. The Nose proper resembles a jiyramid with three sides, the i^osterior of which is wanting and directed toward the nasal cavities. The two lateral surfaces are triangular, covered by skin, and form a part of the face. The apex of the pyramid — the root of the nose — joins the forehead. Below its root it broadens into the bridge or dorsum of tlie nose. Sinking of the bridge of the nose occurs in children who are affected by congenital syphilis, and who suffer from syphilitic coryza or " snuffles." The severe nasal catarrh modifies the nutrition of the surrounding structures, and causes imperfect development of the adjacent bones. The two lateral borders of the nose are coiitinuons with the face. The anterior border is free, and terminates below in the lobule or tip of the nose. The lateral surfaces, below, slope outward into the alse or wings of the nose, which form the lower borders of those surfaces. The base of the nose presents two apertures, the anterior nares, or nostrils, which are separated by a median pillar or columna. The anterior nares are THE NOSE. 285 guarded internally by short stiff hairs, or vihrissa?, which sift small bodies out of the inhaled air. The anterior naros open into the vestibule of the nose, which is the portion of the nasal cavities within the cartilaginous portion of the nose proper. As the base of the nose is in a slightly lower plane than the floor of the nasal fosste, the base of the nose should be elevated with the speculum in making an examination of the nasal cavities. The walls uf the nose proper ai-e formed above by the nasal bones, the nasal spine of the frontal bone, and the nasal processes of the superior maxillary bones ; and, below, by the lateral cartilages of the nose. The skin is loosely adherent to the upper part of the nose, but is closely attached over the alae and lobule. It contains sebaceous glands, which are espe- cially numerous at the lower part of the nose. Therefore, acne and comedones are common in this location. Acne, or pimples, and other inflammatory affections upon the alas and lobule of the nose are painful on account of the density of the tissues, which prevents swelling and causes increased pressure on the nerves. The skin of the nose is also commonly affected by acne rosacea and lupus, especially lupus erythematosus, which develops upon the nose, ears, and face more frecjuently than on other portions of the body. Rodent ulcer, another affection which has a predilection for the nose, frequently commences in the crease between the cheek and the ala of the nose. This is a not uncommon site for epitJielioma. Blood Supply. — The nose proper is supplied by the nasal, angular, infra- orbital, lateral nasal, and superior coronary arteries. The numerous and freely anastomosing vessels of the exterior of the nose communicate M'itli those in the mucous membrane ; hence it happens that in many cases of inflammatory disease of the nasal mucosa there is congestion of the cutaneous vessels. On account of its free blood supply, the skin of the nose offers a good field for plastic operations. Restoration of the nose by a plastic operation is known as rhinoplasty. The flap may be derived from the forehead, as in the Indian method, or from the inside of the arm, as in the Tagliacotian method. The flaps may also be taken from the cheeks, or the flaps from the cheeks may be placed with their cutaneous surface inward and covered with a flap from the forehead. In the nose, as in the scalp, the free blood supply prevents sloughing of portions of the organ almost cut away and then reposited, and small scars are formed in the repair of wounds. Nerve Supply. — The nose proper is supplied by the nasal, infra-trochlear, and infra-orbital nerves. The muscles of tlie nose proper, which have been considered with the description of the face, are supplied by the facial nerve. The veins of the nose proper empty into the ophthalmic and facial veins. There is a network of rather large anastomosing veins in the tip of the nose. 286 SURGICAL AXATOAIV. The lymphatics of the nose i)roiier pass to the submaxillary lymphatic glands. Because of their exposed position and the absence of subcutaneous fat whicli protects underlying vessels, the lobule and alse of the nose, like the pinna of the ear, are frequently fi'ozen and may be the site of gangrene resulting therefrom. Dissection. — Remove the tissues covering the nasal bones and lateral car- tilages of the nose. The nasal bones are tliick and narrow at their upper extremities, and tliin, broad, and much exposed to injury at their lower portion ; consequently these bones are more frequently fractured near their lower margins. A blow at the root of the nose is far more likely to break the cribriform plate of the ethmoid bone and the anterior walls of the frontal sinuses tlian the nasal bones. Fractures of the nasal bones may be reduced by manijmlation of the fragments between the fingers externally and a grooved director introduced into the nasal fossse. Owing to their vascularitj^, the nasal bones unite quickly. In congenital syphilis destruc- tion of the bones, especially of those of the septum, causes the bridge of the nose to sink. Congenital protrusions of the membranes of the brain or the brain itself may occur at the root of the nose. They are known as sincijiital meningo- celes and encephaloceles, ami appear because of incomplete union of tlie frontal bone with the cribriform plate of the ethmoid bone and with the nasal bones. The skin over these tumors may bo highly vascular and present some resemblance to that over a nevus. The cartilages in the framework of the nose consist of a superior and an inferior lateral cartilage and sesamoid cartilages on each side, and the cartilage of the septum. The superior lateral cartilages are triangular. Their anterior margins are partly continuous with the anterior border of the cartilage of the septum, to which they are closely applied. Their posterior margins are closelj^ united to the superior maxilla) and the lower border of the nasal bones. Their inferior borders are attached to the inferior lateral cartilages. Their outer surfaces ai'e covered by tlie skin and the nmscular and iil irons tissue of the nose; and their inner surfaces by the nasal mucous membrane. When the superior lateral cartilage is detached iVdiii tlio nasal bone liy traumatism, considerable pain in the no.se is produced by injury of the nasal nerve, which emerges between this cartilage and the nasal bone. The i)ifcrior hitcral rarfilnr/i's are sharply bent around in front of tlie anterior nares, so that tluy are composed of an inner and an outer portion. The inner portion lies in contact with the corresponding portion of the opposite inferior lateral cartilage on the inner side of tiie anterior naris, forming part of the col- umna. The outer jiortiun is oval and curves backward in the ala of the nose. It PLATE LXVII V' \ Superior lateral cartilage Accessory quadrate cartilages Cartilage of nasal septum . 1 ^ Nasal bone *T^„ Inferior lateral cartilage J Sesamoid cartilages Fibrous tissue of ala of nose LATERAL CARTILAGES OF NOSE. 287 11—19 PLATE LXVIII Cartilage of septum of nose Inferior lateral cartilage Anterior nans if\ Fibrous tissue of ala of nose Anterior nasal spine uf superior nnaxilla CARTILAGES AT BASE OF NOSE. 290 PLATE LXIX, Vertical plate of ethmoid Sphenoid sinus Septal cartilage Inferior lateral cartilage of nose Vomer Groove for naso-palatine n. NASAL SEPTUM. 291 THE NOSE. 293 is attached to the superior hitenxl cartilage and the superior maxilla by dense tibrous tissue, in which the sesamoid cartilages are found. The margin of the alae of the nose is not formed by the inferior lateral cartilage, but by the dense fibrous tissue which forms the framework of the nose projier where the bones and cartilages are absent. The sesamoid or accessory cartilages are usually four in number in each lateral ■wall of the nose proper. Two of these cartilages are situated in the fibrous tissue which connects the inferior lateral cartilage with the nasal process of the superior maxilla. Just above these are the other two, which are called the accessory quadrate cartilages. Additional sesamoid cartilages may be found in the fibrous tissue which completes the framework of the nose proper, but the four previously mentioned are the only constant sesamoid cartilages. The septal cartilage is placed in the antero-inferior portion of the septum, fill- ing the angular interval between the vertical plate of the ethmoid bone and the vomer. It is quadrilateral in form. Its posterior superior border is in contact with the vertical plate of the ethmoid bone, which is sometimes grooved to receive it. Its posterior inferior border joins the anterior nasal spine of the superior maxilla, and the vomer, which may be grooved for its reception. The upper portion of its anterior superior border is attached to the crest on the under surface of the junction of the nasal bones, and below the nasal bones the sides of this border are continuous with the superior lateral cartilages ; it termi- nates just above the tip of the nose between the inner plates of the two inferior lateral cartilages. The anterior inferior border is short, and extends backward and downward, above the columna, to the anterior nasal spine, which it embraces. The cartilages and other soft tissues of the cartilaginous portion of the nose may be destroyed by lupus vulgaris, the bones not being involved. The nose maj'' be repaired by one of the methods of jtlastic operation (rhinoplasty) previously mentioned. Dilating specula introduced into the anterior nares should not be inserted beyond the cartilaginous portion of the nose, on account of the pain produced by pressure upon resisting bony structures. Dissection. — Hold the anterior segment of the skull so that the light enters the nasal cavities through the anterior nares, or pass a probe or a grooved director into the nasal cavities to determine to which side the nasal septum is deflected. Then cut through the tissues of the upper lip and through the lateral cartilages, close to that side of the septum which does not bulge, ^^lth the hard palate facing upward saw through the skull, close to the flat or concave side of the septum. The superior turbinated bone on one side may be broken, in which case it may be studied on the other side after removing the septum. 294 SURGICAL ANATOMY. Tlie Nasal Cavities, or Fossae, two in number, are located between the base of the skull and the hard palate. They are -wide below- and become quite narrow above, where the middle and sui^erior turbinated bones lie near the septum, and at times in contact with it. The vertical diameter of each nasal fossa is greater than the transverse diameter; and, therefore, forceps inserted into the fossae should be opened vertically. The nasal cavities open upon tiie face by means of the vestibule and anterior nares, and into the naso-pharynx by means of the posterior nares. They are separated by the nasal sei)tum. The nasal septum is formed l)y the crest at the junction of the nasal bones, the nasal spine of the frontal bone, the vertical plate of the etlimoid Ijone, the cartilage of the septum, the vomer, the crest of the sphenoid bone, and by the crest situated at the line of junction of the two palatal processes of the two superior maxillse and of the two horizontal plates of the palate bones. In children up to the seventh year and in primitive races the septum is straight in eighty per cent, of cases ; but in the adult in seventy-six per cent, of persons it is deflected to one side, and more frequently to the left. This deflection should not be mis- taken for a bony growth of the septum. The frequency of deviation of the nasal septum is supposed to be due to the practice of alw^ays blowing the nose with the same hand. This condition, by obstructing one nasal fossa, retards breathing and impairs the resonance of the voice, which should be perfect in those who sing. Perforation of the nasal septum may occur in persons exposed to the vapor of chromic acid in the manufacture of potassium l)ichromate, in syphilitic indi- viduals, and in scrofulous persons, or may be a congenital condition. ■ The roof of the nasal cavities is formed Ijy the nasal bones, nasal spine of the frontal bone, cribriform plate of the ethmoid bone, sj^henoid turbinated bones, body of the sphenoid Ijone, alaj of the vomer, and sphenoid processes of the palate bones. Tlie middle portion of the roof, formed by the cribriform plate of the etlnnoid Ijone, is horizontal, its anterior portion slopes downward and forward, and its posterior portion downward and backward. A meningocele projecting through the roof of the nasal fossa into the nasal cavity has been mistaken for a polypus and removed, with a fatal result. In fracture of this ]iortion of the base of tlie skull blood or cerebro-spinal fluid may escape through the nose. The middle portion of the roof of the nose is so thin tliat it may easily be punctured and the cranial cavity entered by slender instruments or foreign bodies introduced in the nose, either intentionally or accidentally. Tlie floor of the nose is wider tlian the ro5f, being slightly more or less than one-half of an inch wide. It is lornuHl liy the ]ialatal processes of the superior PLATE LXX. Superior meatus Superior turbinal Middle turbinal Inferior turbinal Inferior meatus Vestibule Tongue Posterior pillar of fauces Genio-hyo glossus nn Genio hyoid m Hyoid bone Mylo-hyoid m(cut edge) Thyro-hyoid membrane (cut edge) Ventricle of larynx Thyroid cartilage (cut) Diaphragma sellae Cavum sellae Spenoidal cell Middle meatus i Naso-pharynx Orifice of Eustachian tube hlard palate Soft palate Uvula Anterior pillar of fauces Tonsil in recess of fauces Oro-pharynx Epiglottis (cut edge) Aryteno-epiglottidean fold Laryngo-pharynx uprarimal portion of larynx False vocal cord True vocal cord nfrarimal portion of larynx Cricoid cartilage (cut) Ring of trachea MEATUSES OF NOSE AND TURBINATED BONES-LATERAL VIEW. 2m PLATE LXXI, Frontal sinus Straw in infund'-bulum ' Orifices of anterior ethmoidal cells Bulla ethmoidalis Drifices of posterior ethmoidal cells in superior meatus Superior turbinal (cut) Straw in orifice of sphenoidal cell Sphenoidal cell Diaphragma sellae ae Middl. achian tube Hiatus semilunaris Middle turbinal (cut) Straw in orifice of Antrum of Highmore Additional orifice of Antrum of Highmore Straw In nasal duct ORIFICES OF ACCESSORY AIR-CHAMBERS OF NOSE. 298 "'^SE. 209 maxill;i> ami the liorizontal plates of u., >(• bones. It is somewhat concave from side to side, and slojies slightly dowinvani and hackward. The outer wall of the nasal fossa is formed hy the nasal iirocess and internal surfai'c of the snperior niaxilhi. the inferior turhinalcd hone, tin; latM'vnial hone, the lateral mass of the ethmoid inuie, the vertical platt' of the |i;ilate hone, and the internal pterygoid plate of the sphenoid bone. The outer wall is made irregular by projection of the sujierior, middle, and inferior turl)inatcd bones into the nasal cavity. The superior turbinated bone is situated on the upjier part of the outer wall in the posterior one-third of the cavity, its anterior and highest portion l.ieing about opposite the tendo oculi. The middle turbinated bone extends along the posterior two-thirds and the inferior turbinated bone along nearly the whole length of the outer wall of the nasal fossa. The recesses beneath the turbinated bones are called meatuses. Of these there are three — viz., tlie superior, middle, and inferior meatuses, each situated beneath the corresponding turbinated ))one. The superior meatus is closed in front and ojiens downward and backward. It contains the oritices of the sphenoid cells or sinuses and of the posterior ethmoid cells. The orifice of the sphenoid cells is really in the roof of the nasal fossa at the level of the superior turbinated bone, and when that bone is divided into two plates, the orifice is oppo.site the space between them, known as the fourth meatus or spheno-ethmoid recess of Meyer. The middle meatus is open in front, behind, and below. In front it opens into a broad portion of the nasal cavity, called the afriinn of the middle meatus. The atrium opens widely anteriorly into the vestibule, allowing most of the inhaled air to jiass through the middle meatus. On the lateral or external wall of the middle meatus is a groove known as the hiatus semilunaris, which begins at the lower extremity of the infundibulum and curves from above backward and downwai'd. The orifices leading to the antrum of Highmore and to the anterior ethmoid air cells are in this groove. Till' bulla ethmoidalis is the rounded upper boundary of the hiatus semilu- naris. The orifice rif the antrum of Highmore is about an incli above the floor of the nose. The inferior meatus opens chiefly downward and backward, so that more exhaled than inhaled air passes through it. It presents the inferior orifice of the lacrymo-nasal (nasal or lacrymal) duct, which carries the tears from the lacrymal sac to the nose. The opening of the nasal duct is at the under surface of the attached margin of the inferior turbinated bone, about an incli behind the ante- rior hares, and three-fourths of an inch above the floor of the no.?e. Instruments to be introduced into the inferior meatus must be directed toward the floor of the nose, or the anterior end of the inferior turbinated bone will guide them into the middle meatus, wliicli is more widely open. Foreign bodies are most frequently 300 SURGICAL ANATOMY. found in the inferior meatus. If these bodies are retained for a long time, concretions of calcareous matter adhere to them and thus rliinolUhs are formed. The turbinated bones or other portions of the walls of the nasal cavities may be the site of necrosis, which causes a purulent discharge usually from one nostril. The carious bone should be removed, and wlien the disease is situated high uj), Rouge's operation offers a good exposure of the nasal cavities. In this operation the upper lip is everted, and the tissues of the lip and nose are detached from the external surface of the superior maxilke. A chronic purulent discharge from one nostril is usually caused by the presence of a foreign body or carious bone in the nasal fossa or one of its accessory |i cavities ; and from Iioth nostrils by constitutional disease, as syjihilis. The nasal cavities are divided, according to function, into the olfactory portion, Avhicli includes the superior meatus, middle turbinated bone, and upper two-thirds of the septum of the nose, and the respiratory portion, which includes the middle meatus, inferior turbinated bone, inferior meatus, and lower one-third of the septum. The nasal cavities are lined by a mucous membrane (Sehneiderian or pitui- tary membrane) which is continuous with that of the pharynx, sphenoid and ethmoid cells, frontal sinuses, antra of Highmore or maxillary sinuses, lacrymo- nasal ducts, and lacrymal sacs. This continuity with the adjacent mucous membrane and with the lining of the acce.ssory cavities of the nose, as the various air sinuses are called, is very im}iortant to remember, for there is a marked inter- relation existing between the diseases of these various parts. Empyema of the frontal and ethmoid air sinuses, for instance, and of the antrum of Highmore is usually dependent upon disease of the nasal mucosa. In the olfactory jjortion the mucosa is of a yellowish color, which gradually fades below, making no marked line between the mucous menilirane of the two portions. Over the nasal septum it is rather firmly adherent to the underlying periosteum ; at times submucous hematomata of the septum are seen after injury of the nose. On the anterior inferior portion of the septum the mucous memln-ane presents a little diverticulum, which is the remains of Jacobson's organ. This organ is more highly developed in the lower animals. At the upper two-thirds of the septum nnd outer Avail (in tlic olfiictory portion) the mucous membrane is delicate and thin, ;iiid contains the ])r,inc]u's of the olfactory nerve. In the lower or respiratory portion of tlie nasal fo.ssa (he mucous meml)r;in(:'is tiiickei', more vascular, and jiale red in color. This is especially noticeable over the lower Ijorders and posterior extremities of the middle and inferior turbinated liones, where it is soft and boggy and projects beyond tlie 1)ones. This condition is due to the presence of a large number of V(.'ins in tlie sul)nnicous layer of the nmcous membrane of tlie middle and inferior riTE XOSE. ;',01 turl)inatoil bones, and to the prestnu'o ut' fini'inous spaces of erectile ti88ue in tiiat of tlie inferior tnrlnnatetl bout'. In chronic nasal catarrh these cavernous spaces arc distended with blood, the nasal cavity is occluded, and the individual is unable to breathe through the nose. The mucous membrane of the anterior extremity of the inft'rior turl)inated bone, when distended, resembles a polypoid growth. Instruments, such as specula or tubes of atomizers, introduced through the anterior nares should be directed slightly outward to avoid striking the septum, which causes pain, and to prevent injury to the mucous membrane, which often bleeds after slight traumatisms. Mucous polypi are frequently developed in the nose, and usually from the nuicous membrane of the superior or middle turbinated bone or near the hiatus semilunaris. They occlude the nasal cavity, may broaden the nose, compressing the nasal ducts, and may project through the anterior or posterior nares. They should be removed, and if the}' continue to recur, a portion of the adjacent bone should be removed, exercising sufficient care to avoid fracturing the cribri- form plate of the ethmoid bone. Fibrous or sarcomatous polypi arise from the periosteum and more frequently from the roof of the nose. Bleeding from the nose (epistaxis) is one of tlie prodromal symptoms of typhoid fever, but it is more commonly due to other causes, such as engorged vessels, as in plethoric individuals, or ulceration into an artery, and may be a symptom of fracture of the base of the skull, purpura hemorrhagica, hemo- philia, scurvy, or ptomain poisoning, as from large abscesses. Hemorrhage from the nose is checked by the laity liy pressure on the upper lip, which occludes the artery of the septum ; by plugging the anterior nares ; by raising the arm and increasing the expansion of the chest, which lessens the pressure in the veins ; and by drop- ping a cold key down the back, or applying cold water to the back of the neck, and thus stimulating the vasomotor nerves. If the source of a serious hemorrhage can not be found, the bleeding can be checked by plugging both the anterior and posterior nares, which is done by introducing a strong thread, stilfened by soaking in gum and drying, into the nose and pharynx, ami bringing it out through the mouth and attaching a i)lug of cotton to it ; or a soft catheter may be threaded and carried through the nose into the pharynx. One end of the thread is brought out through the month with forceps, and the other through the nose in with- drawing the catheter. A plug of cotton the size of a walnut is then attached to the string, the two ends of which are tied together so that the plug can be pulk'd against the posterior nares, or withdrawn and reapplied if necessary. The instru- ment specially designed for plugging the posterior nares is Bellocq's cannula. Ozena is the name given to any affection of the nasal fossae giving rise to a foul discharge from the nose. A fetid purulent discharge from both nostrils may 302 SURGICAL ANATOMY. be a symptom of atrophic rhinitis, syphilis, carcinoma, glandersj or occasionally necrosis ; and from one nostril a symptom of rhinoliths (incrusted foreign bodies), necrosis, or emj^voma of one of the accessory cavities of the nose. The vestibule of the nose is that portion of the nasal fossa -u-ithin the carti- laginous portion of the nose, and is lined with skin which blends with the mucous membrane of the nose. Tlie mucous glands are most numerous over the jiostcrior portion of the outer wall and septum of the nose. The position of these glands and the backward and downward slope of the nasal floor accounts for the gravitation of the mucus to the pharynx. Occlusion of the duct of a mucous gland causes the formation of a retention cyst. Some lymphoid tissue is also found in the nasal mucous membrane. Nerve Supply. — The nerve supply of the nasal mucous membrane is derived from the olfactory, nasal, and naso-palatine nerves, branches from Meckel's ganglion and the ^^idian nerve, branches from the anterior superior dental nerve, and branches from the anterior palatine nerve. The olfactory nerves, which arise from the olfactory bulb, enter the nasal fossa by piercing the cribriform plate of the ethmoid Iwne as numerous branches. The internal or mesial l)ranches ramify u]>on the upper one-third of the septum, and the external branches upon the sujierior turbinated bones and the surface of the ethmoid above and in front of these bones. They form plexuses in and beneath the mucous membrane. Anosmia, or loss of the sense of smell, after a severe blow upon the head is supposed to Ije due to rupture of the olfactory nerves where thej^ pass through the criliriform plate. The nasal nerve is a branch of the ophthalmic division of the fifth cranial nerve. It reaches the nasal fossa by passing through the slit at the side of the crista galli, runs downward in the groove on the internal surface of the nasal bone, and passes forward between the nasal bone and the upper lateral cartilage to sup- ply the tip of the nose. It supplies branches to the anterior portion of both the outer wall and the septum of the nose. The naso-palatine nerve is a branch of IMeckel's ganglion, and enters the nasal fossa with the naso-palatine artery at the spheno-palatine foramen. It crosses on the body of the sphenoid bone to the septum, upon which it runs downward and forward, supplying its middle portion. The branches from the Vidian nerve and the anterior l)ranclies of Meckel's ganglion ai'e small. They supply the ujtper and back part of the septum and the superior tuvliinntcd bone. They can seldom be traced. The branches of the anterior superior dental branch of the superior maxil- lary nerve supply the inferior turbinated bone and the inferior meatus. The PLATE LXXII Nasal n. Olfactory n. Olfactory tract Superior nasal nerves Spheno-palatine n. Naso-palatine n Great palatine n External palatine n Posterior palatine n Tensor palati m Internal pterygoid m Otic ganglion Sympathetic root of otic gang Middle nneningeal aJ Auriculo-temporal n OLFACTORY NERVES. 303 11—20 PLATE LXXIIl, Nasal septum Anterior nasai spine Middle turbinal -Inferior turbinal ANTERIOR VIEW OF NASAL F08S/E. 30G THE NOSE. 307 branches from the anterior palatine nerve (inferior nasal nerves) run forward upon tlie middle and inferior turbinated bones. Bi.ooD Suri'LY. — The blood supply of the nasal cavities is derived from the spheno-palatine, descending palatine, anterior and posterior ethmoid arteries, and tlu' artery of the septum. Tlie spheno-palatine artery, a branch of the internal maxillary, is the prin- cipal artery of the nasal fossa. It enters it at the spheno-])alatine foramen with the naso-palatine nerve. Its internal branch, the naso-palatine, accompanies the naso- palatine nerve downward and forward upon the septum toward the anterior pala- tine foramen. Its external Ijranches supply the outer wall of the cavity, the ethmoid cells, frontal sinus, and antrum of Highmore. The descending palatine artery is also a branch of the internal maxillary artery. It gives otf a few small In'anchcs to the posterior portion of the outer wall of the nasal fossa. The anterior and posterior ethmoid arteries are branches of the ophthal- mic artery. They supply the roof, upper portion of the septum, and outer wall of the nasal fossa, ethmoid cells, and frontal sinuses. The artery of the septum is derived fi-om the superior coronary branch of the facial artery. It supplies the eolumna and the lower portion of the septum. The veins of the nasal cavities form a plexus under the mucous membrane. The plexus is drained l)y the veins which accompany the spheno-palatine artery and empty into the pterygoiil plexus ; those which follow the ethmoid arteries and empty into the ophthalmic vein ; some which pass througli tlie foramina in the nasal bone and nasal process of the superior maxilla to empty into the facial vein ; and others which pass through the foramen caecum to join the superior longitudinal sinus and through the cribriform plate of the ethmoid bone to join the intra-cranial veins. The lymphatic vessels of the muco-periosteal lining and walls of the nasal fossaj terminate in the post-pharyngeal lymphatic gland, the internal maxillary lymphatic glands, the parotid lymphatic glands, and the superior deep cervical lymphatic glands. Through the cribriform plate of the ethmoid bone these vessels communicate with the intra-cranial lymphatics and the subdural space, affording a channel through which meningitis may be produced by caries of the upper portion of the wall of the nose. Involvement of the posf-]iharyngeal, internal maxillary, parotid, and superior deep cervical lymphatic glands may also result from disease of the nasal fossfe. In anterior rhinoscopy, or examination of the nasal fossa through the ante- rior naris, tlie following structures can be observed : The septum, which should occupy a vertical position, and, if it deviates toward the fossa under examination, it 308 SURGICAL ANATOMY. should not be mistaken for a tumor ; the floor of the nose ; the inferior turbinated bone, which extends backward along the outer wall of the fossa ; the middle meatus ; the middle turbinated bone ; and high up the superior meatus and the anterior extremity of the superior turbinated bone. Posterior rhinoscopy, or examination of the nasal fossse through the posterior nares is quite difficult, and can be performed only after some practice. A small mirror, similar to a laryngoscopic mirror, is inserted behind the soft palate, while the patient breathes through the nose and the tongue is depressed by the examiner. By means of light reflected through the mouth the following structures can be seen : The jjosterior nares, separated bj^ the posterior margin of the nasal septum ; the upper or attached portion of tlie inferior turbinated l)one ; the middle meatus ; the middle turbinated bone ; the superior meatus ; the superior turbinated bone ; the roof of the naso-pharynx ; the upper part of the j^osterior wall of the naso-pharynx ; the pharyngeal tonsil ; the upper part of the lateral wall of the naso-pharynx ; the pharyngeal recess ; and the profile of the trumpet- shaped orifice of the Eustachian tube. Nasal douche. — In nasal catarrh the nasal fossae are frequently cleansed by spraying or douching with an alkaline solution. In using the nasal douche the solution flows in one anterior naris and out through the other, elevation of the soft palate against the posterior wall of the pharynx preventing the solution from passing into the ovo-pharynx. The bottom of the vessel containing the solution should not be placed above the level of the eyebrows, and the head should be inclined slightly forward so that the solution will not enter the Eustachian tubes, the orifices of which are on a level with the posterior extremities of the inferior turbinated bones. If the solution should enter the middle ear through the Eustachian tube, otitis media and deafness might resvilt. Dissection. — The student should now turn the superior turbinated bone upward, and with a probe search for the orifices of the sphenoid sinus and poste- rior ethmoid cells ; remove the anterior portion of the middle turbinated bone, to find the orifices of the antrum of Highmore, anterior ethmoid cells, and the in- fundibulum, and cut away the anterior portion of the inferior turbinated bone to see the inferior opening of the lacrymo-nasal duct. The frontal and sphenoid sinuses have been opened in sawing through the skull, so they can be satisfactorily studied. The frontal sinuses are situated between the inner and outer tables of the frontal bones, at the position of the superciliary eminences and glabella. They are aljsent before the seventh year, when they originate as extensions of the anterior ethmoid cells, and reach their full development at about the twentieth year. The anterior or external bony wall of the sinuses is the thicker of the two, and, upon careful examination, it can usually l)o seen to consist of two lamiiiir, between PLATE LXXIV. Sphenoid cells Apex of orbit Midd dum POSTERIOR VIEW OF NASAL FOSS/E. 309 THK ^•OSI':. ;] 1 1 which there is ;i lliiii ili|ihiic layer. Tlie weakest and thinnest i)()rtiy the malar bone and the body of the superior maxilla. The supra-orbital margin contains the supra-orbital notch — a landmark in operations upon the supra-orbital and infra-orbital nerves. This notch is situated at the junction of the inner one-third ^\•ith the outer two-thirds of that margin, and transmits the supra-orbital vessels and nerves. The roof of the orbit is formed by the orbital plate of the frontal bone and the lesser wing of the sphenoid bone. The frontal sinuses frequently project backward into that part of the orbital roof formed by the frontal bone ; conse- quently tumors or an empyema of the frontal sinus may encroach upon the orbit and cause displacement of the eyeball and double vision — diplopia. At the outer side, near the base of the orbit, the roof presents a large depression — the lacrymal fossa — for the lacrymal gland ; and at the inner side, near the base of the orbit, the small depression to which the pulley of the superior oblique muscle is attached. On account of the relation between the orbit and the cranial cavity and the tenuity of the intervening bony wall, a foreign body with a sharp point, such as a foil or .stick, may enter the orbit, pierce the roof of that cavity, and penetrate the brain without producing an apparently' grave external injury. The floor of the orbit is formed by the superior maxilla, the malar bone, and the orbital plate of the palate bone. Beneath the greater portion of the floor is the antrum of Highmore, tumors of which may encroach upon the orbit, displace the eyeball, niid cause diplopia. Tlif outer wall of the orbit inclines obliquely forward and outward, and is formed by the malar bone, the external angular process of the frontal bone, and the greater Ming of the sphenoid bone. When dividing the optic nerve in excision of the eyeball, the scissors is more readily introduced on the outer side, THE ORBIT. 317 because of the greater space between the eyeball and the outer wall and the out- ward slope of that wall, which makes a larger angle with the optic nerve than does the inner wall. The inner wall of the orbit is tbrnud liy the nasal process of the sujierior maxilla, tiu' intcnial angular process of the frontal bone, the lacrymal bone, the os planum of the ethmoid bone, and the body of the Sfihenoid bone. Near the base of the orbit the inner wall presents a large depression — the lacrymal groove — which lodges the lacrymal sac and below leads into the lacrymal canal, which is lined by the muco-periosteal wall of the lacrymo-nasal duct. In the inner wall of the orbit, and sei)arated from that cavity by a tliin bony jiartition, are the ethmoid cells and the sphenoid cell or sinus. Tumors, empyema, or mucocele of these cells may encroach upon the orbit, displace the ej'eball, and cause diplopia. Measurements. — The antero-jjosterior diameter of the orbit is about one and three-fourth inches. At the base the vertical diameter is about one and one- fourth inches, and the transverse diameter about one and one-half inches. The orbit is widely open anteriorly, and posteriorly it is in comnnuiication with the cranial cavity through the optic foramen and the sphenoid fissure, and with the pterygo-maxillary region and spheno-maxillary fossa through the spheno- maxillary fissure. Blood may be extravasated into the orbit after fracture of one of the -^^-alls of that cavity, more commonly the roof. Tumors, blood, or pus may enter the orbit from the pterygo-maxillary region through the spheno-maxillary fissure, and from the cranial cavity through the sphenoid fissure. Blood extravasated into the orbit produces subconjunctival ecchymosis. Dissection. — According to the level at which the calvaria has been removed, there will be found remaining more or less of the vertical plate of the frontal bone, covered in front by the soft parts. Tlie soft tissues should be turned down after making two incisions down to the bone, one running vertically upward from the nasion and the other running parallel to the vertical incision, and start- ing from the external angular process of the frontal bone. Should there be much of the vertical plate of the frontal bone remaining, it should be removed with hammer and chisel almo.st as far down as the supra-orbital arch. The roof of the orbit should now be removed, either entirely or all of it except the sui)ra-orbital margin, as suggested by Cunningham. In the former method two cuts, converg- ing at the optic foramen, are made with a saw, leaving the bone around the optic foramen undisturbed, and then, by a firm tap with a mallet, breaking away the orbital roof, and turning it forward. In Cunningham's method the thin ])late of bone covering the orbit is removed with a chisel and mallet, leaving intact the 318 SURGICAL AXATOMY. ring of bone around the optic foramen and tliat constituting the supra-orbital margin. Care should be taken to avoid injuring two structures — tlie pulley of the superior oblique muscle and the orbital periosteum. If at the time the dissection of this portion of the bodj- is begun the eyeball has collapsed, it .should be inflated. After the periosteum has been opened, carry a ligature loosely around the ojjtic nerve 1)y means of an aneurysm needle ; then insert a blowpipe between the optic nerve and its sheath, thrusting it almost, if not quite, into the eyeball. Inflate until the ball is tense ; then, wliile an assistant is slowly withdrawing the blowpipe, draw the ligature tight. The eyeball is preferably inflated from the front, this procedure being less difficult, more successful, and allowing rcinflation when necessary. In this method a sharp needle is introduced obli(iuely at the sclei'o-corneal junction. The blow- pipe is then inserted through the puncture, and, after the eyeball is distended, withdrawn. The valvular character of the incision is sufficient to prevent rapid escape of the air. Orbital Periosteum or Periorbita. — Tlie orbital roof having been removed, the perio.steum comes into view. It incloses the structures which fill the orbit, and is but loosely attached to the bony walls. It is continuous posteriorly with the endosteal layer of the dura mater through the optic foramen and the sphenoid fissure. Anteriorly the periorbita divides at the orbital margins into two lamellse — one is continuous with the periosteum on the facial surface of the bones which form those margins, and the other blends with the palpebral fascia of the eyelids. Dissection. — Two incisions are now made through the periosteum. One is transverse, and runs parallel to the supra-orbital ridge ; the other is longitudinal, and runs antero-posteriorlj' from the optic foramen to the middle of the first inci- sion. Either a very sliai'p knife must be used, or else a nick should be made in the periosteum and the rest of the cutting done with scissors or with a knife in the trough of a small grooved director. The two flaps thus formed should be carefully turned aside, gently separating them from the underlying structures. Further dissection is much facilitated liy drawing forward the eyeball and retaining it in position witli a suture or hooks, taking care not to puncture the eyeball, and allow tlie escape of its contained air. Structures Exposed by Removal of the Periosteum. — The orbital fat, orbital fascia, and IVontal nerve are exposed as soon as the flaps of periosteum are reflected. Careful removal of .some of the orliital fat will demonstrate a number of structures. In tlie median line the frontal nerve is I'cadily demonstrable without dissec- tion. It lies upon the levator ])ali)el)r[e su]ierioris muscle, and its anterior portion is accomjianied by tlu' supra-nrbilal artery. PLATE LXXVl, Orbital fascia Capsula of Tenon Fat Superior rectus m, Levator palpebrae superioris m. Connection between superior rectus m. and levator palpebrae superioris m. Capsule of Tenon Fornix conjunctivae Septum orbitale or orhito-tarsal lig. Check lig' of inferior rectus m. blique m Optic n, Capsule of Tenon Orbital fascia ORBITAL FASCIA AND CAPSULE OF TENON-SACITTAL SECTION. 320 PLATE LXXVII Orbicularis palpebrarum m. Ethmoid cells Orbital fascia envel internal Supravaginal lymph space Temporal m. of cranial cavity. J Tenon's space 11-31 ORBITAL FASCIA AND CAPSULE OF TENON-TRANSVERSE SECTION. 321 rilE on BIT. 323 Running along the outer wall of tlie orbit, anI)er and inner margins of the optic foramen. It extends as a fleshy belly along the upi)er and inner part of the orljital wall above the internal rectus muscle. It then narrows into a shining, slender tendon, which enters the ring-like pulley attached to the frontal bone. Leaving the pulley, the tendon changes its course to an outward and a backward direction. It then passes under the superior rectus muscle, any the union of the superior and Infei'ior ophthalmic veins, is short and thick. It passes between the heads of the external rectus muscle, through the sphenoid fissure, and enters the cavernous sinus. The superior ophthalmic vein is considerably larger than the inferior oph- thalmic vein. It commences at the inner portion of the upper eyelid by a free anastomosis with the frontal, supra-orbital, and angular A-eins, and, following a straighter course than the ophthalmic artery, crosses over the optic nerve to reach the inner end of the sphenoid fissure, where it joins the inferior ophthalmic vein to form the common ophthalmic vein. The inferior ophthalmic vein is formed by the union of the inferior muscular and posterior ciliary veins in the lower external portion of the orbit. It lies below the plane of the optic nerve, and communicates with the pterygoid plexus of veins by a twig which passes throngli the spheno-maxillary fissure. It then runs backward to the rear of the orbit, and joins the superior ophthalmic vein, as previously described. The inferior ophthalmic vein, as well as the sui^erior, empties at times directly into the cavernous sinus. Phlebitis of the ophthalmic veins may extend to the cavernous sinus and cause fatal thrombosis. Pulsation of the ophthalmic vein and of the orbit may be produced by an arterio-venous aneurysm between the internal carotid artery and the cavernous sinus. Pulsation of the orbit may also be caused by traumatic aneurysm of one of the arteries of the orbit, or pulsation transmitted to the tenninal portion of the ophthalmic vein from an aneurysm of the internal carotid artery. The Lenticular, Ophthalmic, or Ciliary Ganglion is a small, reddish body, slightly larger than the head of an ordinary pin. It is of quadrilateral outline, and both its surfaces are slightly convex. It lies about one-fourth of an inch in front of the sphenoid fissure, and between the optic nerve on the inner side and the external rectus muscle on the outer side. It is usually situated at the outer side of the ophthalmic artery, to which it is, at times, closely adherent. Like all the sporadic ganglia connected witli the fifth nerve, it has afferent and efferent filaments. The afferent filaments are three in number, and are termed its roots ; the efferent filaments are the branches of distribution. The roots are motor, .sensory, and .?ym]iathetic. Tlie motor, or short root, is derived from tliat braneli of |1r> oculn-motor Ufrvc whirh runs to the inferior oblique nuiscle. It enters the posteriur iufeiior angle of the ganglion. The PLATE LXXXi. Frontal sinu Ofifice of infundlbulu Pulley of superior oblique Tendgn of superior oblique m.- Lachrymal gland Tarsal cartilage of upper eyelid Loop between orbital and lachrymal nerves — Inferior oblique m Bristle in orifice of antrum Antrum of Hlghmore .Supraorbital n. Supratrochlear n. Levator palpebrae m. Lachrymal n. Superior rectus m. Frontal n. Internal rectus m. Optic n. Short ciliary nerves ,Nasal n. Lenticular ganglion External rectus m. Inferior rectus m. Lachrymal n. Jhird n. Sixth n. Ophthalmic division of fifth n. Gasserian ganglion Trifacial or fifth n. ferior maxillary n. maxillary n. ^^^'*>4l!4.i>t§:^^-*>^" NERVES OF ORBIT. 339 THE OnniT. 341 sensory or long root springs from {\w nasal In-ancli of the ophthalmic division of the fifth nerve. It passes along the outer side of the o[)tic nerve, and enters the IKisterior superior angle of the ganglion. The sympathetic root has its origin in the cavernous plexus, and is somewhat difficult to dissect satisfactorily. It enters the hack jiortion of the ganglion in one of three ways: most commonly in com- pany with the sensory root, more rarely alone, in the form of a Ininch of fhie tilanients, and least frequently in company with the motor root. Branches. — From the anterior horder of the ganglion ahout six delicate filaments are given off, whicli run forward to the eyehall and, by subdividing, number twenty when they reach the globe. The}' are termed the short ciliary nerves. They surround the optic nerve and pierce the sclerotic coat in a circle arounout one-tenth of an inch, or 2.5 millimeters, internal to the posterior pole of that organ. It is invested by a sheath of dura mater and arachnoid, and is surrounded by an extension of the capsule of Tenon, the orbital fat and vessels, and the rectus muscles. It is pierced and traversed l)v the vena centralis retinte and arteria centralis retina;. The External Rectus Muscle is seen along the outer wall of the orbit. It has two heads of origin : tlie upper head arises from the outer margin of the optic foramen, beneath the superior rectus muscle, and the lower head, partly from the ligament or tendon of Zinn and partly from a small spine of bone situated on the lower margin of the sphenoid fissure. Between these two heads pass the third nerve, the nasal nerve, the sixth nerve, and the ophthalmic vein. The external rectus muscle is inserted by an expanded tendon into the sclerotic coat of the eye- ball about one-fourtli to one-tliird of an inch behind tlio outm- margin of tlie cornea. Action. — It abducts the cornea. Nerve Supply. — From the abducent or sixth cranial nerve. The Internal Rectus Muscle lies along the inner wall of the orbit, below the superior iilili(|ni' umsclc, oi)litlialiiiic artery, ami nas:il nerve. It arises tliniugh (he ligament or tendon of Zinn from the inner margin of the optic foramen, and is inserted into tlie sclerotic eoat of the eyeball about one-fourth to one-third of an inch lu'liiiid the inner margin of the cornea. .V<'ri(:)N. — It abducts the cornea. Xkkve Supply. — From the inferior division of the third cranial nerve. PLATE LXXXII Pituitary body. \..avernous sinus. 3rd cranial n. cranial n. Internal carotid a. .Ophthalmic n, SECTION OF CAVERNOUS SINUS. Superior division of era Inferior division of '• » '.liUvv.-'- ■■■ Lacrymal n. Frontal n. 4th cranial n. Ophthalmic v. STRUCTURES TRAVERSING SPHENOID FISSURE. 34;^, PLATE LXXXIIL Superior rectus m Tendon of superior oblique m Pulley Corrugatorsupercilii m. Puncta lachrymalia Meibomian gland Conjunctiva Orbital fat Inferior rectus m Inferior oblique m Tensor tarsi m. TENSOR TARSI AND CORRUGATOR SUPERCILII MUSCLES. 346 TIIK UlilUT. 347 Tlic Inferior Rectus Muscle mises from tin- lower margin of tlic optic fiiraiiu'U tlu-uUi;li tlu' iii;aiiH'iil cir trudon of Zimi. It passes forward along the lloor of the orhit and licluw the dptic nerve, and is insei'tcd into the sclei'otic coat of the eyehall alniut iine-t'onrtli to one-third of an inch from the lower margin of tlu' cornea. Action. — It depresses the cornea, adducts it, and rotates it ontward. Nerve Srrri.v. — From the inferior division of the motor oculi or third cranial nerve. The inferior rectus muscle can he hetter studied after the dissection of the vessels, the nerves, and the other nmscles has been completed, and those structures have been removed. Ligament of Zinn. — By observation of the ocular surfaces of the origin of the J'lxir rectus riuisclcs, it will be seen that these muscles arise from a common tendinous ring which is attached around tire optic foramen. This common tendon may be divided into a superior and an inferior common tendon. The stqicrior common teniJoti- is attached to the upper mai'gin and tlio upjier outer part of the margin of the optic ioramen, and gives origin to the superior rectus nmscle, part of the internal rectus muscle, and the upper head of the external rectus muscle. The inferior connnon tendon, or ligament of Zinn, is attached to the lower pai't of the inner margin, the lower margin and the lower part of the outer margin of the optic foramen, and gives origin to the inferior rectus muscle and part of the internal rectus muscle, and the lower head of the external rectus nmscle. Dissection. — The inferior oblique muscle is next exposed. Its position and relations differ nnich from those of the other orbital muscles, and it can best be seen after the following dissection : Release the eyeball from any position in which it may be held. Evert the lower eyelid, and I'emove the conjunctiva from it at the inferior forni.x. Remove the fat lying in the floor of the anterior portion of, the orbit, and clean the expo-sed muscle. In doing this be careful not to cut the nerve which enters the posterior border of the inferior oblique muscle. The Inferior Oblique Muscle arises by a fiat tendon from the orbital plate of the superior maxilla to the outer side of the orbital orifice of the lacrymal duct. It passes outward and Ijackward under the inferior rectus muscle, and then upward between the globe and the external i-ectus muscle. It ends in a membranous temlon which is inserted into the sclera on the uppiT and ()uti_r side of the globe, beloAV and external to the insertion of the superior oblique nuiscle. Action. — It rotates the eyeball outward, and elevates and abducts the cornea. In abducting the cornea it counteracts the tendency of the su])erior rectus muscle anil inferior rectus muscle to ai.lduct the cornea. 348 SURGICAL ANATOMY. Nerve Supply. — From the longest brancli of the inferior division of the oculo-motor nerve, which enters the muscle at its posterior margin. Dissection. — The ocular conjunctiva should now be removed from the scler- otic coat of the eyeball as far forward as the margin of the cornea, so that the positions of the attachments of the four rectus muscles can be observed. The rectus muscles are inserted by thin, flat, slightly expanded tendons into the sclerotic coat of the eyeball, one-fourth to one-third of an inch from the margin of the cornea. Action. — The actions of the rectus and oblicjue muscles of the orbit are some- what complex, as almost every movement of the eyeball is performed by two or more muscles. In considering the movements of the eyeball it must be remem- bered that the globe can not be moved away from its position, in which it is closely retained by the cajjsule of Tenon and the attachments of the orbital fascia, forward movement being prevented by the rectus muscles. The only movements of the eyeball are rotation around any axis of the globe, limited by the attach- ments of the orbital fascia existing between the muscles and the adjacent structures, as the orbital periosteum and the palpebral fascia. These movements are more easily understood if only the motion of the cornea is considered. Adduction of the cornea is performed by the internal rectus muscle, and abduction of the cornea by the external rectus muscle and the two oblicjue muscles. Elevation of the cornea, as in looking directly up\\-ard, is performed by the superior rectus muscle, the inferior obli<]ue muscle preventing adduction of the cornea and rotation of the cornea inward. Rotation of the cornea inward is movement of the uppermost portion of the cornea inward and downward. Depression of the cornea is performed by the inferior rectus muscle, the superior oblique muscle preventing adduction of the cornea and rotation of the cornea outward. Rotation of the cornea inward is performed by the superior rectus muscle and the superior oblique muscle, and rotation of the cornea outward b}' the inferior rectus muscle and the inferior oblique muscle. Rotation of the cornea is not a common movement, and it occurs when the head is inclined to one side. Movement of the cornea in an oblique direction is performed chiefly by two of the rectus muscles, as upward and outward by the superior rectus and external rectus muscles. Excessive action of the various muscles is prevented by the attachments of the anterior lamella of the orbital fascia. Strabismus, or deviation of the sagittal axis of one eyeball from its normal position, occurs when one or more muscles are excessivelj^ active or the opposing PLATE LXXXIV. Tendo ocul Lacryinal sac Lacrymal canaliculus Middle turbinatis bone nferior turbinatis bone Middle meatus of nose Inferior rneatus of nose Lacryino-nasa! duct Antrum of Highmore LACRYMAL APPARATUS, 350 THE LACHYMAL AI'/'ANATUS. ?.5l muscles are insufficiently active. This cnnilition is more commonly caused by defective refraction in the affected eye or unc(iiuil refraction in the two eyes. The first requisite is to correct the defect in refraction, and as a last resort the tendon or tendons of the liy|ieractive niust'le or nnisclcs may l)e divided. A fter division of the tendon, e.\treuic retraction of the nuisele is prevented by tlie anterior lamella ot' the urhital fasi'ia. I)issEcTioN. — The temporo-malar nerve is the last structure to be dissected. The orbital contents must be removed completely, and the nerve will be found in a pad of fat in the retiring angle between the inferior and external orbital walls. The Temporo-malar ur Orbital Nerve arises from the superior maxillaiy nerve in the spheno-maxillary fossa, and reaches the orbit by passing through the spheno-maxillary fis.sure. It then divides into two branches — temporal and malar. The temporal branch forms a loop of communication with the lacrymal nerve, and then runs beneath the orbital periosteum to reach the spheno-malar foramen. Having traversed this foramen and entered the temporal fossa, it pierces the dee]) layer of the temporal fliscia. It runs upward between the two layers of the temporal tascia for a short distance, and pierces the superficial layer of that fascia. It communicates with the temporal branch of the facial nerve, ami is disti'iliuted to the skin of the anterior temporal region. The malar branch runs forward iii the orbital fat, and leaves tlie orbit b}' passing through the malar foramen. It communicates with the malar branch of the facial nerve and supplies the skin of the cheek. The Lymphatics of the Orbit jiass thiough the spheno-maxillary fissure to the internal maxillary and deep parotiil lymphatic glands. THE LACRYMAL APPARATUS. Dissection. — Insert slender probes into the puncta lachrymalia and lacrymal canaliculi, and open the latter as far as the lacrymal sac. The Lacrymal Canaliculi are two narrow canals, one in each eyelid, extend- ing from the lacrymal jmnetum to the lai'rymal sac. For a short distance from the lacrymal punctum the course of each canaliculus is vertically away from the margin of the lid, then, turning abruptly, it forms a right angle, passes inward, and pierces the inner division of the ten<1o oculi to reach the lacrymal sac. Before entering the lacrymal sac the lacrymal canaliculi of the ujipcr and lower lids 352 SURGICAL ANATOMY. frequently join and open into the sac by a common orifice. In passing a probe into the lacrymal canaliculi their angular course should be remembered. Dissection. — Next make a vertical section through the upper and the lower ej^elid, to demonstrate their several layers of tissue. The Eyelids are composed of skin, superficial fascia, orbicularis palpebrarum muscle, areolar tissue, i:)alpebral ligaments, orbito-tarsal ligaments, tarsal carti- lages, Meibomian glands, conjunctiva, vessels, nerves, and lymphatic vessels. The upper eyelid also contains the aponeurosis of the levator palpebrse superioris muscle. The most superficial layer is the skin ; the second layer is the superficial fascia, which contains no fat in this location ; the third layer is composed of deli- cate areolar tissue ; in the fourth layer are the tarsal cartilage, the orbito-tarsal ligament, the palpebral ligaments, the Meibomian glands, and in the upjjer lid the aponeurosis of the levator palpebrte superioris muscle ; the fifth layer is com- posed of conjunctiva and subconjunctival tissue. The eyelids are described in volume I, pages 512-520. Dissection. — Open the lacrymal sac, and, after j^assing a probe through the lacrymo-nasal duct, saw away the anterior wall of that duct. The Lacrymal Sac is the upper, dilated end of the lacrymo-nasal duct, and rests in the lacrymal groove, which is a depression in the lower anterior portion of the inner wall of the orbit. The lacrymal sac is invested by a fibrous capsule, which is attached to the margins of the lacrymal groove, and is continuous with the orbital periosteum. It is lined with mucous membrane, which is continuous with that of the lacrymal canaliculi and lacrymo-nasal duct. Loose submucous tissue attaches mucous membrane to the fibrous capsule. The Lacrymo-nasal, Nasal, or Lacrymal Duct extends from the lacrjmial sac to the uppermost part of the anterior portion of the inferior meatus of the nose. It is directed downward and slightly backward and outward. Its walls are formed by the superior maxillary, lacrymal, and inferior turbinated bones, and are lined l)y mucovis membrane continuous with that of the nose and lacrymal sac, the sac and tlie duct forming the Lacrymal Canal. The nasal orifice of the duct is guarded by a valvular flap of mucous membrane. Tlic Course of the Tears is from the lacrymal gland at the outer part of the ujipcr fiiruix of the conjunctiva and the accessory lacrymal glands in the eyelids, inward over the conjunctiva to the lacrymal puncta, and thence successively tlir(iu,i;li the Iiici-yiiial canaliculi, lacrymal sac, lacrymal duct, and inferior meatus of the nose. IF the lower eyelid is everted or inverted so tiiat the tears do not enter the lacrymal punctum, or thei'e is an obstruction in the lacrymal canaliculi or nasal duct, or the tears are secreted too- rapidly for the capacity of the puncta, as in weeping, the tears flow over the cheek. PLATE LXXXV. Orbicularis palpebrarum Skin Superficial fascia Median'connective tissue Waldeycr's glands ■^^ ■- J^yCorijunctival papillae Conjunctiva Orbicularis palpebrarum Sebaceous gland of Levator palpebrae superioris m. Superior palpebral m.of Mu'ller I? Meibomian glands in tarsal cartilage Duct of Meibomian gland weat gland of Moll II— -23 SAGITTAL SECTION OF UPPER EYELID. 353 PLATE LXXXVl. Superior portion of lacrymal gland Inferior portion of lacrymal gland Levator palpebrae superioris m Frontal sinus Meibomian glands 'Conjunctiva Orifices of ducts of meibomian glands Orifices of lacrymal ducts Tensor tarsi m. Lacrymal sac Lacrymal canaliculi MEIBOMIAN GLANDS AND LACRYMAL APPARATUS. Tin: FATMALL. 357 THE EYEBALL. The eyeball is a globular body, so situated in the orbital fossa as to be pro- tected by the orbital margins from injury by large objects. It is freely movable around its axes, in order that objects may be seen without appreciable muscular effort. Till' mobility of the eyeball is permitted by the relation existing between the globe and the capsule of Tenon, which has been described with the orbit. The eyeball and capsule of Tenon form a ball-and-socket joint. Backward, lateral, vertical, and oblique movements of the eyeball en masse are prevented by the attachments of the orbital fascia to the orbital margins and palpebral fascia, and forward movement of the organ is checked by the rectus muscles ; therefore the only movements of the eyeball are those of rotation around its axes. Exces- sive rotation is prevented by the attachments of the anterior lamella of the orbital fascia and its thickened portions, designated check ligaments. Exophthalmos, or protrusion of the eyeball from the orbit, may be caused l)y tumors or foreign bodies in the orbit, myopia, and enlargement of the eyeball by disease. It sometimes exists slightly after tenotomy of one of the rectus muscles, and may be a sign of exophthalmic goiter. Sinking of the eyeball occurs after partial absorption of the orbital fat in wasting diseases, and is associated with general emaciation. Being a gloliular liody, the eyeball has an anterior pole, located at the center of the cornea ; and a posterior pole, at the center of the posterior segment of the eye, which is the portion covered by the sclera. It also has an equator, midway between the two poles ; an axis, or sagittal diameter, connecting the two poles ; a vertical and a transverse diameter at the equator. It is not quite spheric, because the cornea is a segment of a smaller sphere, and projects forward like a watch-glass, increasing the .sagittal diameter or axis; the transverse is slightly greater than the vertical diameter. The axis, or sagittal diameter, measures about 24.5 millimeters; the transverse equatorial diameter, aliout 23.9 milli- meters ; and the vertical equatorial diameter, about 23.5 millimeters. From these measurements it will be seen that the eyeball is slightly elongated from behind forward, and compressed from above downward. The axes of the two eyeballs are parallel with each other, although the axes of the two orbits are divergent anteriorly. Dissection. — By the time the orbit has been dissected, the liunian eyeball will be so far decomposed that it can not be easily nor profitably dissected. Fortunately, an adequate substitute is found in the eye of a pig, a sheep, or a bullock. Of these, the pig's eye corresponds more nearly in size to the human 358 SURGICAL ANATOMY. eve ; but the bullock's eye, y a layer of sclerotic ti.ssue, called the lamina crihrom. It is white, opaque, and tough, and maintains the normal conformation of the glolje. It consists of interlacing bundles of white, fiT)rous connective tissue. It is thickest posteriorly, and thinnest just behind the insertions of the rectus muscles, about one-fourth to (jne-third of an inch or six to eight millimeters from the cornea, where it is sometimes ruptured in cases of injury to the eyeball. 362 SURGICAL AXATOMY. Between the cornea and the insertions of the tendons of the rectus muscles it again becomes thicker, on account of its reinforcement by hbers from those tendons. In disease of the eye, such as gUiueoma, in which there is increased intra-ocular tension, compression of tlie ciliary nerves against the unyielding sclerotic coat causes intense pain. At its anterior margin the sclerotic coat is directly continuous with the cornea, and the slight groove at this point is called the scleral sulcus. About one-fourth of an inch, or six millimeters, behind the sclero-corneal junction the sclerotic coat receives the insertions of the rectus muscles. At this point also it receives and transmits the anterior ciliary vessels, which form a, ring around the cornea; con- gestion of these vessels is evident in iritis. In the sclera, just Ix-hind the sclero- corneal junction, is a circular l)lood channel surrdundiiig tlie margin of the cornea ; it is called the canal of Sclilemm. This canal transmits venous blood, and is in close relation with certain lymph spaces in the pectinate ligament of the iris, called the spaces of Fontana. In conjunction with the spaces of Fontana the canal of Schlemm, by absorbing the excess of aqueous humor, is .supposed to maintain the normal intra-ocular tension, exaggeration of which results in the grave disease, glaucoma. The lamina cribrosa is in the posterior portion of the sclera, and is the place of entrance of the ojitic nerve, whose dural and pial investments blend with the sclera. Mim;te openings which form a circle around the the lamina cribrosa transmit the jKisterior ciliary vessels and nerves. The point of entrance of the optic nerve is not at the posterior pole or in the visual axis of the eye, but lies about one-tenth of an incli, or 2.5 nun., to the nasal side of, and slightly below, it. As this nerve passes through the sclera it is constricted, and instead of passing as a compact bundle, it is broken up into fasciculi which separatel}^ pierce the fibrous lamina mentioned — the lamina cribrosa. The lamina has an opening in the center larger than tlie perforations produced by the individual nerve bundles; this is called the porus opticus, and transmits the arteria centralis retinae. Except at the entrance of tlie optic nerve and the sclero-corneal junction, the sclerotic is but feebly attached to the subjacent vascular coat. Its innermost layer — whicli, on account of its deep color, is called the lamina fusca — is in relation with the vascular coat, to which it is attached by a layer of loose connec- tive tissue called llic htniiiid stipraclinroiden. The cornea is tlie circular anti'rior window of the eyeball, and comprises about one-sixth of tlic eircumfereiuv of tlie glol)e. It is perfectly transparent, and is somewliat tliinut-r at its center than at its periphery. Its ti-ans|iarcncv is lost in interstitial keratitis (inflammation of the corneal ti.ssue), which is frequently caused by syphilis. It is more highly convex than the remainder of the eyeball, THE EYEBALL. 363 and conseqiu'utly forms part uf a smaller splu're than does the sclera, and hence projects further than dues the latter. The stvideiit can reailily prove this fact hy closing his tiw ii eye and moving the loose skin of the up[)er lid over the globe witli his tinger. The cornea is })art of the fibrous coat of the eye, and at its peri- phery is eontinuous with the sclera. Owing to the fact that the transition of the sclera into the cornea occurs lirst on the inner aspect of the former, the sclera seems to overlap the cornea ; thus the margin of the cornea becomes beveled on its external asjiect and the sclera on its internal aspect. This apparent overlapping being greater above and below than at the sides, the transverse diameter of the cornea slightly exceeds the vertical. It is in front of the aqueous humor, which is interjiosed between it and the iris and lens. The cornea being convex, assists in bringing rays of light to a focus upon the retina. If the convexity of the cornea is excessive, the rays are brought to a focus before reaching the retina, and the person suffers from near-sightedness or myopia. If the cornea is insufhciently convex, the rays reach the retina before being collected to a focus, and the person suffers from far-sightedness or hypermetropia. When the curvature of the cornea is irregular, the raj's of light are not regularly brought to a focus. The error of refraction resulting is known as astigmatism, which may also be produced b}' irregular refraction in the lens. The cornea consists of five layers : the anterior epithelium, the anterior limit- ing membrane (membrane of Bowman), the substance proper, the posterior limiting membrane (the membrane of Descemet), and the posterior endothelium. The anterior epithelium nnd jmsterior endotliclinmof the cornea serve to prevent absorption of li([uid from the tears and from the anterior chamber of the eye. The opacity of the corneal tissue after death is due to imbibition of fluid into the lymph channels of the cornea. If the anterior epithelial layer, composed of the conjunctiva, is broken, and lead lotions are used, lead salts may be deposited and impair the transparency of the cornea. The substance proper (substantia propria) is composed of numerous laminse of modified connective tissue, between which are freely anastomosing lymph channels, through which it is nourished. Like the other layers of the cornea, it contains no lilood-vessels. These vessels end in loops at its periphery. In interstitial kera- titis these laminte are affected, and effusion into the lymph channels causes haziness and loss of ti'ansparency of the cornea. Ulcers and wounds of the cornea, as a rule, heal readily, notwithstanding the absence of l)lood-vessels. Ulcers may, however, perforate the cornea. Perforating ulcers or wounds of the cornea allow the aqueous humor to escape. With the stream of the escaping aqueous humor the pupillary margin of the iris may be prolapsed through the opening in the cornea. Scars resulting from ulcers or 3G4 SURGICAL ANATOMY. wounds of the cornea may produce an opacity resembling a small puff of smoke (nebula), or a pearly white ojiacity, which is designated leukoma. These opacities, if situated at the center of the cornea, interfere with the passage of light to the most sensitive ])ortion of the retina, making it necessary to form an artificial pupil. Abscesses of the cornea gravitate between the laminte to the lower jiart of the cornea, producing a crescentic collection called onyx — because of its resemblance to the crescents at the roots of the finger-nails. These abscesses should be evacu- ated early to avoid perforation, escape of the aqueous humor, and protrusion of the iris. In elderly persons there is frequently seen an opacity of the corneal tissue near the margin of the cornea; this opacity usually begins at the upper part of the cornea, and then at the lower ; subsequently, the extremities of the two hazy crescents meet, and a complete arcus senilis results. This condition is due to fatty or hyaline degeneration of the corneal tissue, probably the result of defec- tive vascular supplj". In pannus the cornea appears to contain blood-vessels. Through irritation from granular lids or inverted eyelashes blood-vessels grow into the corneal con- junctiva, and later may enter the corneal tissue. Staphyloma of the cornea is a bulging forward of a corneal scar and ad- herent iris. It is ])roduced by increased intra-ocular tension pushing forward the iris and even the lens against a weakened cornea, and causing repulsive disfigure- ment. A conic cornea is thin, protnides further forward than normally, and retains its transparency. As a result, vi.sion is imperfect. Blood Supply. — The blood supply of the cornea is indirectly derived from the anterior ciliary and long posterior ciliary arteries. No blood-vessels are found in the cornea, nutrition being supjilied liy imbibition of lymph into the lymph channuls of the cornea. The lack of a direct l)lood supply accounts for the ten- dency of the cornea to become inflamed in poorly nourished persons. Nerve Supply. — The cornea receives a rich nerve supply from the ciliary nerves. Its nerves are merely axis cylinders, and, therefore, r cyclon, the intermediate portion of the middle tunic or uveal tract, is composed of two portions — the ciliary muscle and the choroid portion or ciliary processes. It extends from the posterior, or ciliary, margin of the iris to a point opposite the ora serrata of the retina. In meridional sections of the eyeball it is triangular. The outer side of the triangle is formed by the ciliary muscle, and is in contact with the sclera ; the postero-internal side is directed toward the vitreous chamlier of the eyeball, and contains tlie ciliary i)rocesses ; the anterior side is directed toward the aqueous chamber, and gives attachment to the margin of the iris at about its middle. The ciliary body is well supplied with branches from the ciliary vessels and nerves. Inflammation spreads rapidly from it to the iris, choroid, retina, and cornea. It is called the dangerous area of the eye, because traumatic inflammation of the ciliary l)ody in one eye may be followed by sympathetic oj)htiialniia beginning in the ciliary body of the other eye. This is supposed by some to be due to the rich nerve sn]iply of that region. The ciliary muscle foi'ms a conspicuous white band between the choroid and the iris, and lieijiiid the sclero-corneal junction. It bears on its inner surf^ice the cdiary pi'ocesses. In cross section of tiic ciliary liody or longitudinal section of the eyeball it appears as a triangular band of muscle libers. The shorter anterior PLATE LXXXIX. Vena vorticos Meridional fibers of ciliary in. Circular fibers of ciliary m. Conjunctiva Anterior chamber Lamina supracHoroidea Pupil S— 11-24 EXTERNAL AND MIDDLE COATS OF THE EYEBALL, 369 PLATE XC. Ciliary processes. Suspensory ligament of lens Posterior surface of lens CILIARY REGION (FROM LION'S EYE IN MUSEUM OF UNIVERSIT/ OF PENNSYLVANIA). ?,72 THE EYEBALL. 373 silk' of tlic trian^-le exteiuls IVuin the sclcro-eonu'al jviiu'tion toward the ciliary processes; ami at the angle of juiietiuii of the other two sides it joins the anterior margin of the choroid. It consists of fasciculi oi' nuisealar tissue, the interstices of wliich are tilled with similar strands of connective tissue. The muscular tissue, like all similar structure in the eyeball, is composed of involuntary muscle fibers arranged in two sets — meridional and circular. The meridional or longi- tudinal muscle fibers arise from the sclera and the sclero-corneal junction, ])ass backward, and are inserted into the choroid opposite the ciliary processes. The circular muscle fibers, or ring muscle of Jliiller, are placed internal to the meri- dional fibers in the ciliary body, and encircle the attached margin of the iris. Blood Supply. — The ciliary muscle and ciliary body are supplied with blood from the long jiosterior ciliary and anterior ciliary arteries. Nerve Supply. — The ciliary body and ciliary muscle depend upon the long and short ciliary nerves for their nerve supply, the ciliary muscle being supplied by fibers of these nerves derived from the third cranial nerve. Action. — The ciliary muscle jiossesses the function of accommodation, and permits variation in the degree of convexity of the lens to enable the rays of light to reach a focus on the retina. The ciliary muscle pulls upon the ciliary i)rocesses and relaxes the suspensory ligament of the lens ; lessened tension upon this liga- ment relaxes the capsule of the lens, and allows the anterior surface of the lens to bulge forward. In the hyperopic or long-sighted eye, in wliieh the antero-i)osterior axis of the eyeball is too long, the ciliary muscle is overworked in endeavoring to bring the rays of light from near objects to a focus upon the retina ; consequently, in hj'peropia the ciliary muscle, and especially the ring muscle of Miiller, is hj'per- trophied. After a severe illness, or frequent and long-continued periods of read- ing, this muscle is unable to pei'form the recjuired amount of work, and the hyper- metropic state ensues, which should be relieved by a convex lens. As the third cranial nerve supplies the internal rectus muscle as well as the the ciliary muscle, and does not supply the external rectus muscle, convergent squint is frequently associated with hypermetrojiia. A properly selected convex lens removes the cause of the spasm of the internal rectus muscle, and the strabismus disappears. Dissection. — Secure a fresh eye, and with a sharp, thin-bladed knife or a pair of scissors cut the globe in half slightly anterior to the equator. Scoop out the jelly-like vitreous, leaving intact the lens and its attachments. Place the bowl- like preparation, thus produced, in a shallow tray containing dilute alcohol, and wash out the pigment with a small camel's-hair pencil. A clear posterior view of the ciliary processes will then l)e secured. To see them from in front another dissection should be made. Tiie cornea may be removed by making a circular incision just anterior to the sclero-corneal junction. Four meridional incisions 374 SURGICAL ANATOMY. should be made through the sclera and carried backward to about one-quarter of an inch from the posterior pole of the eye. The flaps thus formed should be pinned back, and the whole preparation placed in dilute alcohol held in a wax- or cork-lined tray. With delicate forceps and scissors the iris is then removed, when an anterior view of the ciliary processes may be had. The ciliary processes are some seventy or eighty irregular projections from the internal surface of the ciliary body. They are longitudinal folds of the forward continuation of the choroid. Their broader extremities are directed forward and form a circle, — corona ciliaris, — which gives attachment to the suspen- sory ligament of the lens. Toward the posterior part of the ciliary body they become less prominent and subdivide, the inner surface of the ciliary body here being almost smooth and forming the orbiculus ciliaris. The ciliary processes are the most vascular portion of the eyeball ; like the choroid, they are composed of a connective-tissue stroma, pigment, and numerous blood-vessels. By osmosis from the blood-vessels of the eyeball the acjueous humor is supposed to be replenished. As the iris and the anterior portion of the ciliary body are continuous and their blood-vessels are in free communication, iritis seldom exists witliout cyclitis ; hence the resultant disease is called irido-cyclitis. The choroid proper extends from the posterior termination of the ciliary body to the optic nerve, bj' which it is pierced. It is found in the posterior portion of the globe, like the sclera, and consists mainly of blood-vessels, areolar tissue, and pigment. Externally, it is in relation with the sclerotic coat, to which it is connected by its outermost layer — the lamina suprachoroidea ; internally, it is in contact with the pigment layer of the retina. It is composed of four layers — viz., the lamina suprachoroidea, the layer containing large vessels, the chorio-capillaris, and the lamina vitrea. Its outer layer, the lamina suprachoroidea, is in immediate contact with the sclera, and is composed of loose areolar, nonvascular tissue containing pigment. This layer is so loosely connected with the lamina fusca of the sclera that extensive hemor- rhages may occur between the sclera and choroid after traumatism of the eye. The third and fourth laj^ers are vascular in character. The third is the layer of choroid stroma, and contains large blood-vessels. The most conspicuous of these vessels are the four venx vorUcosie, each of which is formed liy numliers of veins converging at one point and forming a whorl. They are located at eciuidistant points along the equator of the eyeball, and to them the small veins converge, returning the blood from the whole uveal tract. The chorio-capillaris is the inner vascular layer, and is composed of capillary Idood-vessels. The lamina vitrea, vitreous or glassy lamina, is the fourth or internal layer. It supports the retinal pigment, whicli usually adlieres to it when tlie retina is removed. PLATE XCI. Scle Choroid Vena vorticosa CILIARY NERVES, 376 PLATE XCII. Long posterior ciliary a Long posterior ciliary n Vena vorticosa Chorio-capillaris Circulum iridis rtiajor Conjunctiva Short posterior ciliary a Short posterior ciliary n. Cornea Circulunn iridis minor Anterior ciliary v. Anterior ciliary a. CILIARY ARTERIES. 377 THE EYEBALL. 379 The choroid contains so much jiignient that it is one of the few structures affected hy primary melanotic sarcoma. Tlie ciliary nerves have two sources of origin — the long ciliary nerves arise from the nasal lirancli of the ophthalmic nerve, and the short ciliary nerves spring from the lenticular ganglion. They pierce the sclera around the optic nerve, and pass forward between the sclera and the choroid ; at the posterior jiart of the globe thej' groove the inner surface of the sclera and are intimately attached to it. They pass forward to the ciliary body, where they break up to form a plexus, from whicli fil>ers are distributed to the ciliarj' muscle, the iris, and the cornea. Compression of these nerves against the resisting sclera in increased intra-ocular tension, as in glaucoma, causes intense pain in the eyeball and anesthesia of the cornea. The ciliary arteries consist of the short posterior, long posterior, and anterior. The short posterior ciliary arteries are from twelve to twenty in number ; they pierce the sclera around the optic nerve, and are distributed to the choroid. The long posterior cilia nj arteries pierce the sclera just external to the circle formed by the perforations for the short ciliary arteries, and run forward in the choroid. In the ciliary body around the attached margin of the iris they anastomose with the anterior ciliary arteries. These inosculations form the circulum iridis major; branches from this circle enter the iris, and at the outer margin of the sphincter muscle of the iris anastomose and form the circulum iridis minor. The anterior ciliary arteries are eight in number, two arising from each of the arteries which supply the rectus mu.scles. They pierce the sclera near the sclero- corneal junction, and enter into the circulum iridis major. The ciliary arteries and nerves are ahso described with the orbit. The veins which have their origin in the middle coat of the eyeball are the venae vorticosse and the anterior ciliary veins. The venae vorticosee have been previously described with the choroid and the orbit. The anterior ciliary reins arise from small veins in the ciliary muscle, and pierce the sclera near the margin of the cornea, receiving A'eins connected with the canal of Schlemm. They also receive conjunctival and episcleral veins, and empty into the veins which accom- pany the arteries to the rectus muscle. DisSECTiox. — The choroid, ciliary body, and iris should be carefully stripped from that eyeball in which they were exposed. This should be done under diluted alcohol, and when completed, the retina will be seen. If a portion of the detached choroid is inspected, on its inner surface irregular black patches -will be observed. These are fragments of the pigment layer of the retina which have become detached on account of their firm adhesion to the lamina vitrea of the choroid. 380 SURGICAL ANATOMY. The Retina, the third and innermost coat of tlie eye, is the nervous tunic. It is the end organ of the optic nerve speciahzed for the function of vision. Mor- phologically, it extends from the point of entrance of the optic nerve at the foramen sclerse to the free margin of tlie iris. It consists of three parts : The posterior portion is situated between the choroid and the vitreous body, and extends from the optic nerve entrance to the ciliary body, where the retina suddenly becomes thin along an irregular line, thus forming the ora serrata. This posterior jKirtion is called the optic part, or pars optica retinae, and tci-min- ates at the ora serrata. The next portion, the ciliary part, or the pars ciliaris retinae, lines the inner surface of the ciliary body, extending as far forward as the insertion of the iris. The anterior portion lines tlie internal surface of the iris, and is called the pars iridica retinae. The pars optica retinse is the only part which has much visual function ; because the pars ciliaris and pars iridica retinae are mainly continuations of the pigment layer beyond tlie ora serrata, at which the highly specialized layers of tlie retina suddenlj- diminish in thickness. When viewed from the interior, a circle is seen at the point of entrance of the optic nerve. This is called the 02:)tic disc. It is sometimes called the j^orus opticus, but this name should be applied only to the foramen in the lamina crib- rosa traversed by the central artery of the retina. This disc lies one-tenth of an inch or two and one-half millimeters to the inner side of the posterior pole of the eye. As this is the blind spot of the retina, it is placed outside of tlie direct line of vision. Exactl}' in the center of the retina, at the posterior pole, and in the direct line of vision, a small j-ellow spot, called the macula lutea, is seen in a fresh eye ; the depression in the center of the macula lutea is termed the fovea centralis. The macula lutea is the point at which vision is most acute. For that reason it is situated in a line with the centers of the lens, pupil, and cornea, so that it receives the rays of light brought to a focus by. the lens. Eays from other points, passing through the lens, strike other portions of the pars optica retina^ and produce collateral vi.sion, which is less distinct. The retina is derived from the two layers of the optic cup, which is an extension of the anterior cerebral vesicle and is, therefore, ectodermic in origin. The outer layer of the cup remains as the pigment layer of the retina, while the inner layer gives rise to the remaining and more specialized portion of it. During life the inner layer is ]iink and transparent ; but after deatli it becomes hazy and opaciue. Blood Supply. — The blood suii])ly of the retina is derived partly from the arteria centralis retime, which can be seen entering the ej'e at the optic disc. It gives off an asct'iiding and a descending branch, each of which has a small nasal PLATE XCII Retinal artery Retinal vein Macula lutea Optic disc RETINA OF POSTERIOR ONE-HALF OF RIGHT EYEBALL (ENLARGED). 381 PLATE XGIV. Canal of Schle Conjunctival v Anterior ciliary Central vein of retina_ Conjunctival a. Anterior ciliary a. Long posterior ciliary a. Short posterior ciliary arteries artery of retina BLOOD-VESSELS OF EVEBALl (AFTER LEBER). 384 THE KY KHALI.. 385 branch. Like the vessels oi' the brain, lungs, etc., its branches are end arteries, not anastoniosint;- in the substance of the retina with each otberor witli the ciliary arteries. Pi'dliably the greater portion of tlie nourishment of the retina is derived from the iiostcrinr ciliary vessels, through the chorio-capillaris of tlu' choroid. The retinal veins converge to form two ves.sels which enter the optic nerve at the optic disc, aiul soon join to form one vena centralis retina;, which pursues a course in the nerve corresponding to that of the artery. Dissection. — The metliod of Anderson Stuart will be found the most satis- factory for studying the vitreous body and lens. A perfectly fresh eyeball should not be used : it should be kept from one to three daj's before being utilized, according to the season of the year. The three tunics are divided at the ecpiator and turned back. This is done carefully and over a vessel of diluted alcohol, into which the so-called " eye kernel," composed of the vitreous body and lens, is allowed to fall. The " eye kernel " is then placed in a strong picrocarmin solution for a few minutes, and when removed, it should be well washed. By this method the hyaloid membrane, the lens capsiile, and the zone of Zinn are stained red. If tlie solution is shaken gently, the coloring matter may enter the hyaloid canal, which may thus be recognized. The Vitreous Body is a soft, gelatinous, perfectly transparent substance, composed of semi-solid connective tissue. It occupies the posterior cavity or vitreous chamber of the glol>e. The vitreous chamber is bounded behind and laterally by the retina, and in front by the lens and the zone of Zinn. The vitreous body consists of the vitreous substance, inclosed b}^ the hyaloid membrane, except anteriorly, where the vitreous substance comes into dii'i'ct contact with the lens capsule, receiving the lens into a depression, the patellar fossa of the vit- reous body. It has an indistinctly reticulated structure, and may contain small corpuscular bodies which occasionally produce shadow's upon the retina, the so- called musCcB volitantes. Running from the optic disc to the center of the posterior surface of the lens is a narrow canal, lined by a prolongation of the hyaloid membrane, and called the hyaloid canal, canal of Stilling, or canal of Cloquet. During fetal life this canal transmits an artery to the lens, the hyaloid artery, and in the adult contains the remains of the supporting connective tissue or rarely an atroidiied vessel. The Zone of Zinn, Zonula of Zinn, or Suspensory Ligament of the Lens, is the thickened portion of the hyaloid membrane extending from the ciliary body to the lens. At the ora serrata tlie hyaloid membrane becomes attached to the ciliary body and remains so attached as far as the peripheral or anterior ends of tlie ciliary processes. From the apices of the ciliary processes thick bamls of tlie hyaloid menibrane pass over to the lens, going to its ])eriphery and 386 SURGICAL ANATOMY. anterior surface. The hyaloid membrane, in this region, is thrown into numerous folds, caused by the plications of the choroid portion of the ciliary body, to which it is so closely apposed. At the ciliary margin of the ligament these folds become converted into stiff fibers, which form two series. One series consists of those fibers which spring from the apices of the ciliary processes ; the other, of those which spring from the depressions between the processes. The former are inserted into the periphery and adjacent jiarts of the posterior portion of the capsule of the lens, arid the latter go to the anterior surface of the lens, blending with the super- ficial layers of the anterior portion of the lens capsule. The lens is, in this manner, maintained in its position. The tension of the zone of Zinn is varied by contraction of the ciliary muscle ; when this muscle contracts, the suspensory ligament is relaxed ; tlms, the lens is less firmly com- pressed, and by its own elasticity becomes more convex, and its focal distance is decreased. This function is known as accommodation. The Canal of Petit is a narrow lympliatic channel which encircles the margin of tlie lens, is triangular on section, and is bounded in front by the anterior lamina of the suspensory ligament of the lens, behind by the hyaloid membrane, and internally by the capsule of the lens. It is subdivided into two portions by the fibers of the posterior lamina of the suspensory ligament of the lens. The lymph in the canal of Petit is derived from the ciliary vessels, and is supposed to supply nutrition to the lens. Dissection. — By carefully inserting a fine lilowpipe into the canal of Petit it may be distended 1)v air or a colored fluid. When so dilated, it presents a series of sacculations, due to the undulations in the zone of Zinn produced by the ciliary processes. Remove the lens by cutting through the zone of Zinn Avith a pair of scissors. The Crystalline Lens is a biconvex, circular- body, lying behind the iris and aqueous humor, and in front of the vitreous body. Its rounded margin is a sliort distance from, and parallel with, the corona ciliaris of the ciliary body, to which it is firmly attached bj^ the suspensory ligament of the lens. The center of the anterior surface of the lens is the anterior pole, and the center of the posterior surfiice is the posterior pole. The convexity of the anterior surface of the lens is not so great as that of the po.sterior surface. The central jiortion of the anterior surface is opposite the pupil, and in contact with the acpieous liumor of tlie anterior chamber. At the margin of this central portion the lens is in contact with the posterior surface of the puinllary margin of the iris ; external to this margin the curvature of the lens carries it away from the iris ; this interval between the lens and iris is the posterior chamber of the eye, and is filled with part of the aqueous humor. Posteriorly, tlie lens is received into tiie i)atel!ar fossa of PLATE XCV. THE DARK AREAS REPRESENT THE LENS, IRIS, AND CILIARY BODY AT REST; AND THE BROAD OUTLINES INDICATE THE CHANGED POSITION OF THOSE STRUCTURES DURING ACCOMMODATION (AFTER FUDHS). EMMETROPIC EYE. 388 MYOPIC EYE, PLATE XCVI. MYOPIC EYE WITH CONCAVE LENS. HYPEROPIC EYE. HYPEROPIC EYE WITH CONVEX LENS. 389- TUI-: EYF.BM.L. 391 tlio vitrt'iius lioily. rcri|ilRTally, it is in rclatinn with the /.one of Ziiiu inul tlie eaiial ol' I'elit. The lens is composed of the lens capsule and the lens substance. The capsule of the lens is the stront;-, elastic, transparent membrane which surrounds the lens sul)stance. Tlie lens substance is a transparent, gelatinous material, translucent in the cadaver, and composed of transparent fibers joined liy a trans- parent cement. The cortex, nr peripheral pDrtinn, is soft, anv tlie cornea and behind by the iris and that portion of the li-ns whii'li presents at the pupil. It rommunicates with tlie posterior chamber tiirough the pu])i!. At its external angle it is bounded by the pectinate ligament of the iris. Tiiis angle, which is formed by the peripheral portions of the cornea and iris, is called the muile or s//)((.s of the anterior chamber, or the filtration angle. Knowledge of the anatomy of 392 SURGICAL ANATOMY. the structures at this angle is most important, for it is here that the excess of the aqueous humor escaj)es into tlie spaces of Fontana, and thence In* way nf {\w canal of Schlemn into the anterior ciliary veins, thus reducing intra-ocuhir tension. Hypopyon is a collection of pus in the anterior chamber of the eye, and arises from suppurative inflammation of the cornea, iris, ciliary body, and choroid. Pus passes from the ciliary body through the pectinate ligament of the iris or the attached margin of the iris to reach the anterior chamber, causing cloudiness of the aqueous humor, and its solid portion gravitates to the most dejsendent jiart of the anterior chamber, varying its position with movements of the head. Hy- popyon is crescentic in form, like onyx, but the latter is stationary. The posterior chamber of the eye is a circular space, triangular on cross- section, and situated behind the iris. It is bounded in front l)y the iris; behind, by the lens and zone of Zinn ; and externally, by the anterior portion of the ciliary body. It is limited internally l)y the jjupillary margin of the iris. The Lymphatic System of the Eyeball contains no lymphatic vessels except tho.se of the conjunctiva, the lymph being in spaces. These sjjaces are divided into an anterior and a posterior set. The anterior lymph passages of the eye include the lymph spaces of the cornea and iris, and the anterior and [)osterior chand)ers of the eyeball. The Ujmph tspaces of the cornea are situated between the lamellae of the corneal substance. At the periphery of the cornea the lymph flows into the conjunctival lymphatic vessels. The lymph spaces of the iris open into the a(|ueous humor of the anterior chamber of the eye at small indentations called the crypts of tJie iris, and at the periphery of the iris communicate witli tlie spaces of Fontana. Tlie aqueous humor is composed of lymph situated in the anterior and pos- terior chambers of the eye. It is secreted in the posterior chamber from the plexus of vessels in the ciliary body, and partly from the vessels in the posterior surface of the iris. The aqueous humor passes from the posterior cliamber through the i)uitil into the anterior c'liambfr of tlie eye, and escapes by way of the spaces of Fontana, the canal (.if Scldennri, and the anterior ciliary veins. The posterior lymph passages of tlie vyc include the hyaloid canal, the peri- cJioroid space, Tenon's sjiace, the intervagiual space of tlie oj)tic nerve, and the supra-vaginal space. 'I'be Injitloid raviil, ov ccnlral (■.•uial ol' Die vitreous body, extends from tlie optic disc forward In (he postci'ior jiole of Ibe lens. In the embryo it contains tlie hj'aloid artery, wbirli disappears later, altbuugji (ln' caiiMl remains as a lymph cliainiel wJiich is drained by the intervagiual si)ace of the optic nerve. The perichoroid Jijmph s^wce, situated between the choroid and the sclera, is PLATE XCVII, Lens Suspensory I Cornea Anterior chamber terior chamber JULAR POSTERIOR SYNECHIA. 394 THE EYE BALL. 395 continued along the vessels of the choroid and especially along the veno3 vorticosae. Its lymph escapes into Tenon's space hy [lerf'o rations in the sclera around the veufe vortieosie. Tenon's space, situated between the sclera and Tenon's capsule, drains the \k'vi- choroid spat'c, and opens into the supra-vaginal space. The iidcvcagimd lijtnph space is situated between the dural and pial sheaths of the optic nerve, and is subdivided into a subdural and subaracinioid space by the extension of the arachnoid membrane of the brain along the optic nerve. It opens into the subdural and subarachnoid spaces of the brain. The suprar-vaginal lymph space is situated between the dural sheath of the optic nerve and the posterior extension of Tenon's capsule. The greater portion of the lymph of the eyeball escapes by way of the chambers of the aqueous humor, spaces of Fontana, canal of Schlemm, and ante- rior ciliary veins ; consequently, any obstruction in the anterior lymph channels causes increased intra-ocular tension. Such obstruction occurs in annular posterior synechia, in which tlie whole pupillary margin of the iris is adherent to the ante- rior surface of the capsule of the lens, and prevents the lymph of the posterior chamber, which is derived from the ciliary vessels, from entering the anterior chamber. The pressure thus produced in the posterior chamber causes the peri- pheral portion of the iris to project forward against the cornea, obliterating the tiltration angle, or sinus of the anterior chamber, and preventing escape of Ij'mph from the anterior chanrber of the ej'eball. In this manner the serious disease of the eye, glaucoma, which is characterized by increased intra-ocular tension, is produced. Glaucoma also develops from conditions not so readily demonstrable, as hypersecretion of lymph, and other causes of retention of lymph, in the eye- ball. In emmetropia, or normal vision, parallel rays of light or those from distant objects are l)rought to a focus on the retina when the eye is at rest, and divergent rays or those from near objects do not reach a focus on the retina without some exercise of the function of accommodation. Normal vision occurs in an eye whose axis, or sagittal diameter, is of the normal length, and whose media pos.sess the proper refractive index. In hyperopia, hypermetropia, or far-sightedness, the axis, or sagittal diameter of the eye, is usually too short, although liyi)eropia may be due to absence of the lens, decreased convexity of the refracting .surfaces of the eye, or diminished jiower of refraction in tlu- refractive media of the eye. The result is that when the ciliary muscle is at rest, parallel rays of light or those from distant objects, and divergent rays or those from near objects, come in contact with the retina before being brought to a focus, forming circular ditiusion of the light 396 SURGICAL ANATOMY. and a blurred image. The ciliarj- muscle compensates for the defect by contract- ing and allowing increased convexity of the lens ; but the severe strain causes local and remote disorders, and, on account of failure of the muscle to jserform the work required, reading becomes difficult. The defect is corrected by converg- ing the rays with convex glasses. In myopia, w near-sightedness, the antero-posterior, or sagittal, diameter is too long, and parallel rays of liglit are brought to a focus in front of the retina, so that distant objects are indistinct because the image is blurred. Divergent rays or those from near objects at a certain distance are brought to a focus upon the retina. Myopia occasionally results from increased refractive power of the lens; when this occurs in an old i)erson, second sight is {produced and convex glasses may be discarded. As there is no mechanism in the eye which can com- pensate for the defect, and the patient can see near oljjects, continued ej'e strain may cause more serious disease of the myopic eye. The defect is corrected b}' concave glasses whieli cause the I'aysto diverge. Exenteration of the orbital contents is performed for malignant disease. The external canthus is split, and the orbital contents, including the periosteum, are all removed except at the apex of the orbit. Evisceration of the eyeball is performed in staphyloma of the cornea and dis- figuring leukoma. Tlie cornea is circumcised at the .sclero-corneal margin, and all the contents of the globe and the middle and internal coats of the eyeball are care- fully removed, leaving the sclera intact. The opening is enlarged vertically and a glass ball is inserted into the cavity of the eye. The sclera is stitched vertically over the glass ball and the conjunctiva transversely. After the wound heals, an artificial shell may he inserted over the stump. Enucleation or excision of the eyeball. — The eyelids are separated with a speculum, and tlie ocular conjunctiva is divided close to and entirely around the cornea. The conjunctiva and capsule of Tenon are pushed backward over the eye. The rectus muscles are grasped witli forceps at their insertions and divided l)ack of the forceps. The globe is drawn forward and inward, and the optic nerve and adjoining structures are divided with scissors along the outer side of the eyeball. The eye is then drawn out of its socket, and the remaining adherent tendons and other structures are severed. The cavity is irrigated with cold sterile water, anI!(;AX of IIEAUING. The organ of iK'ariiiu- consists of tln\"c jiovtions — tlio external, middle, ai)d internal ear. Tlie External Ear ("niiu'isi's thr nuride or ]iiinia and tlie meatus auilitorius externns ; the former is of hul sh^lit im|)()rtance physiologieallv ; the latter is the eanal whieh leads inward to the tympanic memhrane. The Middle Ear is eomjiosed of tlie tympamim. the mastoid antrum, and the mastoid cells. The tymjianum, an air chandler, eon]munii'ate.s with the naso-pharynx hy means of the Eustachian tuhe, and contains a chain of movable bones — the auditory ossicles. The mastoid antrum and mastoid cells are air chambers accessory to the tympanum. The Internal Ear, or Labyrinth, is made uji of a complex arranj^ement of cavities ; it contains a fluid, — the perilymph, — together with a membranous cast of the bony structures known as the membranous labyrinth ; the latter contains the endolymph, and within it are the specialized neuro-epithe- lial cells and the terminations of the auditorv nerve. THE EXTEItNAL EAR. The Pinna consists of a pliable framework of yellowy elastic cartilage covered with integument. The external surface is concave, and conducts the .sound waves to tiie external auditory meatu.s, yet accidental ov intt'utional amputation of the piinia causes but sliglit diminution in acuteness of hearing. The outer concave surface presents a number of elevations and dejiressions. The helix is the in- curved border of the pinna. At the free border of the helix there is often to be seen a more or less prominent, rather triangular projection, known as the Dar- winian tubercle ; it is analogous to the pointed tip of the ear of quadrupeds. The fossa of the helix is the groove formed liy the inward curvature of the helix. In front of the helix, and i-unning parallel with it, is a rounded prominence, the antihelix, which divides anteriorly and above into two jxirtions inclosing the fossa of the antihelix (fossa scaplioidca). The antihelix curves around a large con- cavity, — the concha, — which leads to the external auditory meatus. Anterior to the concha is a Munt projection, the tragus. This is i-cally a jtortion of the wall Sri'i'LY. — The arteries, wilh wliich the pinna is avcU su]i]ilied, are ili-rivcd friiiii llii' posterior auricular, occipital, and .superficial tem])oral arteries. They are accompanied by c'orresponding veins. PLATE XCIX. Helix Darwin's tubercle Helicis major m. Tragicus m. Fibrous band is minor m. Obliquus auris m Tpansversus auris m. Fissure of Santorini Antitragicus m. Processus caudatus S— 11—26 INTRINSIC MUSCLES OF PINNA. 401 THE ORGAN OF HEARING. 403 Nerve Supply. — The scnsofv iutvcs of tlio j)inna ;uv devivud i-l:ii'tly iVoni tlie auriculo-temporal and auiiculaiis magiius, altliough filaments are coiitriliutrd by the occipitalis niiiu>r ami tlie auricular branch of the vagus nerve; the motor nerves to the muscles of tiie auricle arc derived from the facial nerve. As the back of the pinna is suiiplied by the auricularis magnus and small occipital nerves and the lobule by the auricularis magnus nerve, pain in the pinna may be caused by irritation of the cervical nerves in caries of the cervical vertebne or by enlarged cervical lymphatic glands. The lymphatics of the pinna are numerous, and pass to the preauricular or superficial parotid lymphatic glands and to the posterior auricular lymphatic glands. The External Auditory Canal is a slightly curved passage, convex upward, which leads inward and a little forward for a distance of about twenty-four milli- meters, or one inch, to the membrana tympani. The highest portion of the canal is about at its middle. Drawing the pinna upward and backwai'd has a tendency to straighten the canal ; this is done prior to inspection of the canal or to introduction of instruments. Owing to the obliquity of the tympanic mem- brane, the anterior and inferior walls of the external auditory meatus are the longer, and the internal extremity of the canal is wedge-shaped, terminating in a narrow recess — the sinus of the external auditor}' meatus. Small foreign bodies which have lodged in the sinus of the canal must be removed carefully, as the instruments must approach the membrana tympani closeh'. The meatus is elliptic at the external orifice, the vertical diameter of the canal being the greater ; near the mefnbrana tympani the transverse diameter is the greater. Although the orifice of the external meatus is elliptic, ear specula which are round are more desirable than the elliptic instruments, for they can be rotated while being introduced. The outer one-third of the wall of the external auditory meatus is cartilaginous and continuous with the cartilage of the pinna ; this portion is about eight millimeters, or three-eighths of an inch, in length, and the cartilage presents one or two fissures, known as the incisure Santorini, wliich are filled with fibrous tissue. The inner or osseous portion is somewhat longer, and measures less in diameter than the cartilaginous portion, its average length being about sixteen millimeters, or five-eighths of an inch. At birth the osseous portion is represented merely by an incomplete bony ring, — the annulus tympanicus, — and a mass of epithelial cells and cerumen fills the canal. The Integument lining the meatus is thin, and firmlj' attached to the under- lying parts ; consequently inflammatory processes, such as furuncles, are accom- panied by considerable pain ; the cutaneous lining is continued OA-er the tympanic membrane as a delicate covering, forming the outer layer of that structure. 404 SURGICAL ANATOMY. Hairs and sebaceous glands are found in the cartilaginous portion of the meatus, as M'ell as slightly modified sweat glands whiclr secrete the cerumen, or ear wax. When the cerumen, or wax, is secreted too rapidlj^ the meatus becomes occluded, and deafness and tinnitus aurium result. No hairs or glands are found in the osseous portion of the external auditory meatus. In otitis externa the skin of the external auditory meatus is inflamed, and there may be a purulent discharge from that canal. Occlusion of the external auditory meatus may occur as a congenital defect or from the presence of polypoid growtlis arising from granulations projecting through a perforation in the membrana tympani in chronic otitis media, from exostoses from the bony wall, from foreign bodies, or from an excessive quantity of cerumen. Foreign bodies may remain in the external auditory meatus for many years without causing injury or inconvenience, and they may not be discovered until otoscopic examination for some condition in no way connected with the presence of the foreign body. Unskilful attempts at removal have inflicted nearly all the injury following the presence of these foreign bodies. No attempt should be made to remove a foreign body until it is seen in the meatus. Insects or other foreign bodies may be removed by syringing gently with a slender stream of warm water. If this fail, a small hook, which can be made of a hair-pin, should be inserted and kept in view, the canal being well illuminated. If the walls of the canal are swollen, removal of the foreign body should be deferred until the swelling has subsided. Relations. — A portion of the parotid gland is in relation with the lower and anterior wall of the •external auditory meatus ; this explains how parotid tumors can cause narrowing of that canal, and how abscesses of the parotid gland might open into it, the fissures in the cartilage affording a favorable situation for perforation. The anterior wall of tlie meatus is also in relation with the condyle of the lower jaw, so that firm closure of the mouth has a tendency to narrow the lumen of the meatus. "When the condyle is driven forcibly back- ward, as by a blow or a fall on the chin, tlie bony wall of the meatus may be fractured. The posterior and upper walls of the canal are formed by parts of the mastoid and of the scpiamous portion of the temporal bone, and often only a thin, osseous partition separates it from the mastoid cells, so that caries of the osseous wall of the external auditory meatus may be followed by mastoid disease. Blood Sui'it.v. — Tin- blood supply of the external auditory meatus is derived from liranches of the internal maxillary, posterior auricular, and super- ficial temp(ii-al arteries. PLATE C, Attic Tensor tympani m. Pinna Internal carotid a, Eustachian tube External auditory meatus Internal carotid a. Membrana tympani Stapes EXTERNAL AND MIDDLE EAR. 405 THE ORGAN OF HEARING. 407 The niiis arnnniiany the etinvspomUiig arteries ami eiiipt}' into tlie teiuiiural, internal maxillary, and posterior auricnlar veins. Nkkvk Srri'i.v. — The nerve .'^ujijily of the external auditory meatus is derived tVom hranehes of the aurieulo-temporal, the avirieularis niagnus, and the auricular branch of the vagus nerve. Interesting reflex disturbances are at times caused by the presence of foreign bodies, wax, or specvila through irritation retleeted along the auricuhir branch of the imeumogastric nerve and referred to the ]iarts supplied by the parent trunk ; coughing, faintness, and nausea and vomiting may be induced in tliis manner. Sneezing is also produced by the pres- ence of foreign bodies or specula in the external auditory meatus. The irritation is reflected probably along the aurieulo-temporal nerve to the Gasserian ganglion or other centers of the , fifth nerve, and tlience referred to the nose through branches of the superior maxillary nerve. Cough produced by irritation reflected from the ear is termed ear cough. Earache associated with toothache in the upper teeth may be explained in tlie same manner. Earache frequently is associated with toothache in the lower teeth and disease of the tongue ; the pain in the ear is due probably to irritation reflected along the inferior dental nerve and lingual nerve, and referred to the ear through the auriculo-temjioral, the other sensory branch of the inferior maxillary nerve. The lymphatics of the external auditory meatus follow the veins, and terminate in the parotid and posterior auricular lymphatic glands. DissECTiox. — The tympanum is to be opened with a chisel l)y the removal of its bony roof (tegmen tymj)ani) ; the opening is made to the outer side of the elevation produced by the superior semicircular canal, and is enlarged carefully, uncovering also the mastoid antrum and the internal auditory meatus. THE MIDDLE EAR. The Middle Ear, or Tympanum, is a small, irregular air chamber, situated in the petrous portion of the temporal bone, and lined with mucous membrane ; it is interposed between the external auditory meatus and the internal ear. Its antero-posterior lengtli measures about twelve millimeters, or onedialf of an inch ; its widtli is from two millimeters to four millimeters, or from one-twelfth to one- sixth of an inch, and it is narrowest opposite the center or umbilicus of the tympani.c membrane which is opposite the promontory ; vertically it is about thirteen millimeters, or somewhat more th^n half an inch, in dei^th ; this last measurement includes the recessus epitympanicus, or attic. The attic, or recessus epitympanicus, is the highest portion of the tympanic cavity. It is situated above the level of the membrana tympani. 408 SURGICAL ANATOMY. and contains the head of the malleus and part of the incus, and leads into the mastoid antrum. The roof of the tympanum consists of a thin j^late of bone — tegmen tympani — which separates the tympanum from the cranial cavity ; it forms part of the antero-superior surface of the jjetrous portion of the temporal bone. Destruction of this osseous lamina or extension through it of the inflammatory process in chronic otitis media may lead to meningeal or cerebral complications, such as extradural abscess, meningitis, abscess of the temporo-sphenoid lobe of the cerebrum, and cereliellar abscess. In children under one year of age the presence of the petro-squamosal suture in the tegmen tympani favors this complication. The floor is formed by a thin, bony plate situated between the tympanum and the jugular fossa. Destruction of tliis plate of bone by caries in otitis media may cause fatal hemorrhage or septic thrombosis of the internal jugular vein, embolism, and metastatic abscess. The anterior wall is cjuite narrow, and is deficient superiorly, inasmuch as the Eustachian tube opens into the tympanum in this situation about four milli- meters, or ftne-sixth of an inch, above the floor. Just above the entrance of the tube is the opening of the canal which lodges the tensor tympani muscle. Owing to the position of the tympanic orifice of the Eustachian tube above the level of the floor of tlie tympanum, fluid which has entered the tympanum by way of the Eustachian tube, through snuffling water in surf-bathing or in using the nasal douche, can not all escape through the tube, and otitis media is likely to result. Below the orifice of the Eustachian tube the anterior wall is composed of a thin, bony lamina, situated between the tympanum and the carotid canal. Caries of this thin plate of bone may occur in otitis media, and ulceration into the internal carotid artery with fatal hemorrhage may follow. The Eustachian tube is fthe anterior extension of the tympanic cavity Avhich connects the middle ear with the naso-pharynx ; it passes inward, downward, and forward from the tympanum, is about thirty-five millimeters, or an inch and a half, in length, and in its several portions varies from two to five millimeters, or from one-twelfth to one-fifth of an inch, in diameter. It consists of an osseous and a cartilaginous portion, the former being about twelve millimeters, or one-half of ail inch, long, and the latter about twenty-five millimeters, or one inch, long. Tlie cartilaginous portion is somewhat trumpet-shaped, being widest at the pharyvf/eal orifice. It is formed by a cartilaginous plate which is triangular in shajje and folded ujion itself, thus leaving on the inferior and external aspect of the tube an interval which is filled with fibrous tissue (fascia salpingo-pharyngea), ami by a |iiirt nf the tensor jialati muscle called the dilator tubie. (See also description nf jihaiynx.) The bony portion, which is smaller than the carti- PLATE CI. Suspensory ligament of malleus Prussak Membra External ligament of malleus gracilis tympani tendon External a g process of incus meatus Processus brevis Manubrium of malleus Cutaneous layer' Mucous layer Fibrous layer' Eustachian tube Canal for tensor tympani m, Stapes Membrana tympani ANTERIOR VIEW OF RIGHT TYMPANUM. 409 \ THE OnOAy OF UFA RING. -411 laginous portimi of tlie tube, is situated at the junction of the squamous and petrous portions of tlie temporal bone ; the isthmus iubfc, its narrowest portion, is situah'd at the junrtiuu of the bony and i'artilai;in(ais parts. Tlie Eustachian tube is lined with mucous nicndirane which is continuous with that of the naso-pharynx and tliat lininj;- tlie middle ear. Conseqviently inflammatory l)roccsscs of the naso-i)haryn.\, by direct continuity of the tissues, may lead to involvement of the middle ear. The tympanic orifice of the Eustachian tube is situated in the anterior wall of the tympanum, about four millimeters above the floor of that cavity, and the pharyngeal orifice is in the lateral wall of the naso- pharynx, beliind the posterior naris, at the level of the posterior extremity of the inferior turbinated bone. Normally the canal is closed, except during swallowing, when it is opened by the tensor palati muscle, levator palati muscle, and the salpingo-pharyngeus, which is the portion of the palato-pharyngeus muscle attached to the Eustachian tube. The action of these muscles during swallowing affords an opportunity to inflate the middle ear by way of the nose, naso-pharynx, and Eustachian tube. In Politzer's method of inflation of the middle ear the patient takes some water in his mouth ; the nozle of a caoutchouc bag which contains air is inserted into one nostril ; the nostrils are closed with the fingers of one hand ; and as the patient swallows the water the bag is suddenly and forcibly compressed with the other hand. In the method of Valsalva the patient closes the mouth and nose firmly and pufls out the cheeks liy a forcible effort at expiration. Air is driven through the Eustachian tube, and a sense of pressure and fullness is felt in the middle ear. This method is not altogether safe, on account of the increased ten- sion produced in the blood-vessels and the danger of hemorrhages and apoplexy. The middle ear may also be inflated by the caoutchouc bag and Eustachian catheter; tlie metlioil for introducing the catheter is described with the pharynx. The Eustachian tube may be closed by the extension of hypertrophic nasal and naso-pharyngeal catarrh into the tube, or the pharyngeal orifice of the tube may be obstructed mechanically by growths of the nose or naso-pharynx. Occlusion of this tube causes autophony, or loud but muffled sound of the individual's voice, tinnitus aurium, or false sounds in the ears, a sensation of ten- sion or distention in the ears, and more or less deafness. In the mucous membrane of the Eustachian tube and near the pharyngeal end of the tube there are a few mucous glands and a quantity of lymphoid tissue ; this latter is sometimes referred to as the tubal tonsil. Relations. — On the outer side of the Eustachian tube are the tensor palati and levator palati nniscles, the otic ganglion, the inferior maxillary nerve, and the middle meningeal artery ; on the inner side is the wall of the phar^^nx. 412 SURGICAL ANATOMY. Blood Supply. — The blood supjjly of the Eustachian tube is derived from the ascending pharyngeal, middle meningeal, and Vidian arteries. Nerve Supply. — The nerve sujiply of the Eustachian tube is derived from the Vidian nerve and the tympanic plexus. The posterior wall of the middle ear presents at its upper portion a large opening which leads into the mastoid antrum ; through this opening the mucous membrane is continuous from one cavity to the other, so that inflammation in the middle ear may lead to involvement of the mastoid air cells. Below the ojiening into the antrum, near the inner wall of the tympanum and posterior to the fenestra ovalis, is a hollow, cone-shaped projection known as the pyramid, at the summit of which there is a perforation for the passage of the tendon of the stapedius muscle. External to the pyramid is the iter ckordas posterius, through which the chorda tympani nerve passes. As the Mastoid Antrum and Mastoid Cells communicate with the middle ear, they are cavities accessory to the tympanic cavity. The mastoid portion of the temporal bone contains numerous spaces, some of which are filled with air ; these communicate with the middle ear, and are called mastoid cells ; other spaces which occupy the tip of the process are filled with marrow. Of the air cavities, the mastoid antrum is the largest and most important. Leidy described the mastoid antrum as a part of the tympanum. The Mastoid Antrum is an air cavity of variable size, usually about that of a large pea, or from four to six millimeters in diameter, and is situated posterior to the tympanum, about on a level with the highest part of that cavit^^ It is lined with mucous membrane or muco-periosteum, which is directlj' continuous with that of the attic of the tympanum and mastoid cells. The mastoid antrum is present at birth. The roof of the mastoid antrum (tegmcn antri) is a thin plate of bone about one millimeter in thickness, situated external to the eminence produced by the superior semicircular canal ; it separates the mastoid antrum from the cranial cavity, and is perforated by minute veins which empty into the superior petrosal sinus ; at times the tegmen is distinctly cribriform, and it may be partly or wholly absorbed in old age. The floor of the antrum, which is not infrequently on a lower level than the communication between the tympanum any a tliiiinor ami Inoscr j^irtion of tiic niciiiliraiif, known as the mciithnina Jlaccidn, or Shrapncll's nwiiibranc. Tiic UK'nilirana tynqiani consists of three layers: an outer cuticular covering-: a niiildlc, iitirons h\yer ; and an inner, mucous lining. Inspection. — When vicwnl through a speculum during; lite, the mcndirana tympani is of a jn'arly ,t;i'ay color, and a]i}iears smooth and jiolishech I'Lvtendiui;- downward and backward with its ai)ex at the umbo is a co)ie of lii/hl, which is of value in the diagnosis of disea.se of the tympanum and memhrana tympani. The handle of the malleus and its short process, and, posterior to the handle of the malleus, the long process of the incus, can frequently be seen through the membrane. From the short jirocess of the malleus two folds extend to the margins of the notch of Ilivini ; these are known as the (niterior and t\ie jDostcrior fold of the membrane, and between them is the membrana flaccida, so named on account of its laxity. Owing to this laxity perforations of the membrana flaccida give rise to but slight loss of hearing. The remainder and major portion of the drum is known as the mevibmna tensa. Perforation or rupture of the membrana tympani is frecjuently produced by traumatism, as by slender foreign bodies accidentally pushed far into tlie external auditory canal, or by the escape of jnis in otitis media. Perforation of the mem- brana flaccida occurs more commonly when the disease is confined to the attic ; perforation of the posterior portion, when the disease is confined to the mastoid antrum ; and perforation of the lower portion of the membrana tensa is most frequent on account of its low position. Owing to the inela,sticity of the mem- brane, perforations do not gape much. Traumatic perforations heal readily, whereas tho.se associated with suppurative otitis media seldom close. Granulation tissue from the inflamed mucous membrane of the tympanum projecting through the perforation forms polypoid growths which conceal the opening, and sometimes hide the tympanic membrane. These growths are associated with copious sup- jiuration. Paracentesis of the tympanum, or puncture of the tympanic membrane, is frequently practised by the surgeon to relieve tension and allow of the discharge of inis. The point selected is in the lower or subundiilical portion of the mend)rane, or wherever the bulging is greatest. Paracentesis of the upper portion of the mem- brane is attended by danger of injuring the malleus, incus, or chorda tympani nerve, and jiaracentesis of the lower portion of the membrane must be cautiously performed, for the inner wall of the tympanum is situated only from two milli- meters to four millimeters, or from one-twelfth to one-sixth of an inch, internal to the tympanic membrane. 420 SURGICAL ANATOMY. After the membrana tympani has been destroyed by ulceration and the malleus and incus have escaped with the pus, a plug of cotton inserted into the tympanum against the stapes will serve as an artificial membrana tympani. Blood Supply. — The blood supply of the membrana tympani is derived mainly from the tymjaanic branches of the internal maxillary ami internal carotid arteries. Nerve Supply. — The chief nerve supplying the external surface of the membrana tympani is the auriculo-temporal. According to Sappey, Arnold's nerve (the auricular laranch of the vagus) supplies the lower portion of this surface of the membrane, and branches from the tympanic plexus supply the inner surface. The membrane is quite sensitive. The inner wall of the tympanum presents several points for examination. A conspicuous rounded elevation, the promontory produced by part of the first turn of the cochlea, is seen ; on it are faintly marked grooves for the tympanic plexus of nerves. Above the posterior portion of the promontory is a transverse oval foramen, — the fenestra oralis, or oval window, — which leads into the vestibule, and when the ear ossicles are in situ, is closed by the base of the stapes. Behind, it is the pyramid, at the summit of which is an opening for the tendon of the stapedius muscle. Below the promontory is ihe fenestra rotunda, or round window, an opening which leads into the scala tympani of the cochlea, and in the recent state is closed by the membrana tympani secundaria. At the junction of the inner wall and roof of the tympanum, above the oval window, is a rounded ridge of bone passing antero-posteriorly ; this is produced by the fecial canal or aque- ductus Fallopii, which lodges the facial nerve. The bony lamina separating this nerve from the cavity of the middle ear is quite thin, especially in children, and in otitis media tlae facial nerve may become affected by neuritis, leading to paralysis of the muscles of expression upon the corresponding side of the face. The mucous membrane of the tympanum lines the tympanic cavity, and is continuous with the mucous membrane of the Eustachian tube and with that of the mastoid antrum. It forms the inner layer of the tympanic membrane, and is reflected over the ossicles, the tendons which enter the tympanic cavity, and the nerves of tlie middle ear. Middle ear disease m;iy lie folldwed liy various complications, tlie most com- mon of whicli is inflanunation of the mastoid .-inlrum and mastoid air cells, result- ing in mastoid abscess. As tlu' mucous membrane of the middle ear is directly continuous with that of the mastoid antrum, it will readily be seen how the inflammatory process maj' extend from the nose to the naso-i)harynx. Eustachian tulie, tym])annm, mastoid antrum, and inastoid cells. Througli carious destruction of the tegnien antri or tegmen tympani or PLATE CIV. Head of malleus Tecmen tym Suspensory ligament cf inalleus ,Chorda tympani n. nous Posterior ligament of incus Orifice of Eustachian tube Tensor tympani m Internal surface of membrana tympani Handle of malleus INTERNAL VIEW OE RIGHT TYMPANUM, 42-2 THE nil(!A.\ OF UKAUIXi}. 423 tlinniii'li tlu' ]n'ri\':isciil:ii- 1\ nipliatics ami the vi'in.>< wliicli pierce tlie tegmen, extradural abscess, meningitis, thrombosis of the superior petrosal sinus, and cerebral and cerebellar abscess nuiy loult from otitic; media and inastoid disease. Thrombosis of the sigmoid sinus and i(iuse(|iiiid septie embolism may occur by extcnsicm ut' the inliaiunuitinii alniio- the veins IVdni the mastoid antrum, mastoid cells, and tympannni whieh cuiiily intu the sii;iiHiid sinus. Ill otitis media the pus usually escapes by perforation of the niembrana tympani, and may pass out through the Eustachian tube into the pharynx, or through the canal for the tensor tymjiani muscle. In mastoid disease the pus usually escapes through the tympanum and membrana tympani, and may, after destruction of the comjiact bone on tlie intracranial surface of the mastoid process, enter the I'ranial cavity and form an extradural abscess ; or it may enter the neck over or under the prevertebral fascia, point on the extei'ual surface of the mastoid process, or est-ijie directly into the external auditory meatus. The Auditory Ossicles consist of the malleus, the incus, and the stapes, whii-h form a chain of three small bones that transmit the impulses of sound waves from the membrana tympani ti> the perilymph and endolymph of the internal vay. The ossicles and the ligaments and teutlons attached to them are covered by the mucous mend>rane of the tympanum. ~ The malleus, or hammer, consists of a head, a neck, a handle, or manu- brium, the iirocessus lirevis, and the processus gracilis. The rounded Itead is situated in the attic, the highest portion of the tympanic cavity, and above the level of tlie membrana tympani ; it is connected with the roof of the cavity by fibrous ti.ssuo which forms the so-called svprrior ligament uf the malleus. On the posterior aspect of the head of the malleus is a cartilage-covered surface which articulates with the body of the incus. Below the head of the malleus is the neck. The manubrium, or handle, is connected with the fibrous layer of the tymjianic membrane, and is situated between this layer and the mucous lining. The processus hreris is a small prominence below the neck, and gives attachment to the tensor tyiii])ani muscle. The processus gracilis is a long and slender process which passes forward to the Glaserian fi.ssure. In the adult it is often largely represented by fibrous tissue. The incus, or anvil, resembles in shape a bicuspid tooth witli diverging fangs ; it consists of a body and two pi'ocesses. The body presents a concavo- convex articular surface for the head of the malleus ; the joint between these bones is surrounded by a capsular ligament and lined by a synovial mendirane. Tlie sJwrf process pas.ses backward, and is connected to the posterior wall of the tym])anum by fibrous tissue. Tlie loitg process descends almost jxarallel witli the manubrium of the malleus, but posterior and internal to it. It terminates in a 424 SURGICAL ANATOMY. small, knobbed projection, the so-called o.s orbiculare, which articulates wiUi the head of the stapes. The stapes, or stirrup, consists of a head, a neck, two crura ur branches, and a foot-piece or base. The head articulates with the os orbiculare of the incus. This joint has a capsular ligament, and is lined by a synovial membrane. The two crura diverge as they leave the neck, are grooved on their concave sides, and are attached to the foot-jnece or base, M'hich fits into the oval window. The base of the stapes is united to the margin of that opening by fibrous tissue. In otitis media the ligaments associated with the ossicles become indurated and stiffened ; through loss of mobility the chain of bones can not transmit imjiulses to the internal ear, and deafness supervenes. In such cases hearing may be improved liy removal of the jierforated membrana tympani, the malleus and incus, or by massage administered by means of sound. Caries of the malleus and incus not infrequently occurs in otitis media, and they are occasionally dis- cliarged with the pus in that disease. The Ligaments situated in the tympanum are associated with the ossicles. They consist of the .superior, the anterior, the external, and the internal ligaments of the malleus, the ligament of the incus, and the capsular ligaments. The superior or suspensory ligament of the malleus is a slender, fibrous band which is attached to the outer part of the roof of the tympanum and to the highest part of the head of the malleus. It limits downward and outward movement of the head of the malleus and inward rotation of the manubrium of that bone. The anterior ligament of the malleus is a strong, fibrous band wliich sur- rounds the processus gracilis of the malleus. It is attached to the anterior wall of the tympanum around the Glaserian fissure, and to the anterior aspect of the head and neck of the malleus. It limits movement of anj' amplitude except in a for- ward direction. It occasionally contains muscular fibers, and has been described as the 1(1. rotor tijmpani muscle. The external ligament of the malleus is fan-shaped. Its apex is attached to the neck of the malleus, ami its base to the margins of the notch of Rivini. It limits outward rotation of the handle fif tlie malleus. The internal ligament of the malleus is the sheath of the tendon of the tensor tympani muscle, and extends from the ti]) of the processus cochleariformis to the margins (if tiie insertion of the tmisor tymjiani tendon, whieh is near the root (if tile liaiidle of the malleus on its inner surface. It limits outward move- ment of the iiandle of the malleu.s. Tile ligament of the incus is a sliort. thick l>aiid wliieli attaches the ex- tremity of Die short process of the incus to the posterior wall of the tympanum near the orifice of the mastoid antrum. THE OHdAX OF HEARING. 425 The capsular ligaments ^urinmul \\w articulations bctwwn tin- luallcus ami incus, and tlie incus and stai^es. The Muscles of the Tympanum are the stapedius and the tensor tympani. The stapedius muscle takes its origin from the interior of the pyramid ; its tendon passes through an aperture in the apex of the pyramid, and is inserted into the neck of the stapes. Nerve Supply. — The nerve su])i)ly of the stapedius muscle is derived from a branch of tlie facial nerve. Action. — It draws the head fif the stapes backward, tlius pressing tlie posterior part of the base of that bone against the border of tlie oval wIikIow, and regulating the pressure in the vestibular contents or perilymph and cndo- lymph. The tensor tympani muscle is larger than the stapedius muscle, and is situ- ated in a bony canal which lies parallel with the Eustachian tube. It arises from the cartilage of the Eustachian tulie, tlie adjacent surface of the great wing of the sphenoid bone, and the walls of the canal in which it lies. The tendon of the muscle winds around the end of the processus cochleariformis, passes outward in the tympanum, and is inserted into the handle of the malleus near its root. Nerve Supply. — The nerve sujtiily of the tensor tympani muscle is derived through a branch from the otic ganglion, from the motor root of the ti'ifaeial or fifth cranial nerve. Action. — It draws the malleus inward, thus tightening and steadying the mcrabrana tympani and compressing the perilymph of the internal ear. Ab- normal action of tliis muscle is one of the causes of snapping, buzzing, or ringing sounds in the ears. Blood Supply of the Middle Ear. — The blood supply of the middle ear is derived from the tympanic branches of the internal maxillary and internal carotid arteries, stylo-mastoid branch of the posterior auricular artery, the petrosal branch of the middle meningeal artery, and a branch of the ascending pharyngeal artery whirh passes up the Eustachian tube. The veins of the middle car empty into the temporo-maxillary vein, the supe- rior petrosal sinus, the lateral sinus, the internal jugular vein, and the pharyngeal veins ; numerous small venous channels pass through the tegmen tymj^ani, eom- municatins with the veins of the dura mater. These veins afford paths by which inflammatory processes may extend from the tymjianum to the venous sinuses, internal jugular vein, meninges, and In-ain. The Lymphatics of the Middle Ear terminate in the posterior auricular and parotid lymphatic glands. Nerve Supply of the Ty.mpanum. — The nerve supply of the tymjianum is 426 SURGICAL ANATOMY. derived from numerous sources, for there are several nerves which enter tlie tym- panic plexus of nerves. The relation of the facial nerve to the tympanum has already been con- sidered. The chorda tympani nerve, a branch of the facial nerve, enters the tym- % panum through an opening in the posterior wall (iter chordffi posterius), passes >Q- -^through the outer portion of the middle ear near the upper part of the tympanic ^v% o membrane, crosses the handle of the malleus, and then enters a small, bony canal tf ^^ (iter chordas anterius) near the Glaserian fissure. In the middle ear it is covered by the tympanic mucous membrane. Involvement of this nerve in otitis media may lead to abnormalities of the sense of taste on one side of the anterior portion of the tongue. The tympanic plexus of nerves ramifies in the grooves on the promontory and inner wall of the tymitanuni, and supplies the mucous membrane of the tympanum. It is formed l)y the tympanic branch of the glosso-pharyngeal nerve, a branch of the great superficial petrosal nerve, a branch of the small superficial petrosal nerve, and the small deep petrosal nerve. Tlie tympanic branch of ilie glosso-pharyngeal nerve arises from the petrous ganglion of the glosso-pharyngeal nerve, and passes into the tympanum througli a foramen in the floor near the inner wall of the tympanum. The branch of the great superficial petrosal nerve; which is derived from the facial nerve, passes into the tympanum through a foramen in the inner wall of that cavity just anterior to the oval window. The bnnirh of tlie small superficial petrosal nerve, which is also derived from the facial nerve, enters the tympanum near the canal for the tensor tymiiani muscle. The small deep petrosal nerve, or tympanic branch of the carotid plexus of the sympathetic nerve, enters the tympanum through the carotico-tympanic canal. Tiie motor nerves to the tensor tympani and stapedius muscles have already been described. Otitis media and dentition. — Acute otitis media is frequently associated with eruption of the teeth, and is also believed to result from reflected irritation pro- duced by carious or by artificial teeth. This complication of dentition may be explaiiu'd l)y tlie connection existing between the nerves which su2:)ply the tynipiinuiii ;ind tliose supplying the teeth. The great superficial petrosal nerve communicates with the tympanic plexus of nerves and, through the Vidian nerve, joins Meckel's ganglion, which is associated with the superior maxillary nerve. The nerves to the upper teeth are derived from the superior maxillary nerve. The small superficial petrosal nerve communicates with the tympanic plexus PLATE CV. Superior semicircular canal Ampullae First turri of cochlea Cupola of cochlea' Vestibule Fenestra ovalis Fenestra rotunda Posterior semic'rcular canal External semicircular canal EXTERNAL VIEW OF BONY LABYRINTH, OR COCHLEA AND SEMICIRCULAR CANALS. 4-27 PLATE CVI, Lamina Posterior semicircular canal External semicircular canal Superior semicircular cana or and nals tibuli Orifice of aqueductus cochleae "^XJ^ '%^j?»> INTERIOR OF OSSEOUS LABYRINTH OF LEFT INTERNAL EAR, :!() THE ORG AX OF IIEMUNG. |:U of nerves, and joins the otic ganglinn, wliirh is associated witli the inferior maxillary nerve. The inferior dental nerve, which snpplies the lower teeth, is a branch of the inferior niaxillarv nerve. THE INTERNAL EAR. The Internal Ear or Labyrinth. — The most important portion of the organ of hearing consists of a series of complex cavities — the l)ony labyrinth, within which is the menibranons labyrinth. The Bony Labyrinth is made up of tliree intercommunicating cavities, — the vestibule, the cochlea, and the semicircular canals, — which are lined by a delicate periosteum. The membranous labyrinth is a cast of tlie bony labyrinth, but is considerably smaller than the latter ; between the two there is a .sjiace lined witii endothelium and containing a tiuid called the perilymph. The parts of the membranous labyrinth are the utricle, the saccule, the membranous semicircuhxr canals, and the duct or canal of the cochlea, all of which are lined witii epithelium and contain the endolymph. The vestibule, situated between tire cochlea and semicircular canals, is an ovoid bony cavity, the antero-postei'ior diameter of which is about five millimeters, or one-fifth of an inch. On the outer or lateral wall is the oval uindow in com- munication with the tympanum ; as previously stated, this is closed in the natural state by the base of the stapes and the periosteal lining of the vestibule. At the anterior portion of the inner or median wall is a round depression, the fovea ]i/inispherica, the bottom of M'hicli is pierced by numerous small openings for the transmission of the vestibular branch of the auditory nerve. Posterior to the fovea hemispherica is a vertical crest, the crista vcstihull. In the posterior portion of the inner wall is the small opening of the aqueductus vestibuli, a canal which extends to the posterior surface of the petrous portion of the temi^oral bone, and lodges the ductus endolymjDhaticus and a minute vein. At the lower and anterior portion of the vestibule is the comparatively large opening leading to the scala vestibuli of the cochlea. In the posterior portion of the vestibule are the five round openings of the semicircular canals. On the roof of the vestibule is an oval fossa, the fovea hemiellipfica. The semicircular canals, tln-ee bony tidies about one-twentieth of an incli, or one and one-fourth millimeters, in diameter, are situated behind the vestibule. The superior semicircular canal lies nearly in the sagittal plane of the body, the posterior, in the coronal plane, and the external, in a transverse plane ; conse- Cjuently they occupy positions about at right angles to one another. Each forms // 432 SURGICAL ANATOMY. more than a semicircle, and upon one extremity of each canal is an enlargement, the ampulla. They open by five orifices into the vestibule, as the non-ampulkited extremities of the superior and posterior canals join, and have a common orifice. From the positions of these canals in the sagittal, coronal, and transverse planes, it may be inferred that the\' are in some way associated with the maintenance of ecjuilibrium. The occurrence of vertigo from increased pressure in the perilymph and endolymph increases the probability of this theory. The cochlea is situated anterior to the vestibule. When isolated from the in- vesting bony substance it appears as a cone, the apex of -which looks outward and somewhat downward and ibrward. The hase is perforated by numerous foramina for branches of tiie auditory nerve, and is directed toward the meatus auditorius internus. The base is nearly two-fifths of an inch, or ten millimeters, in diameter, and the height of the cone is about one-fourth of an inch, or six millimeters. The cochlea consists of a nearly horizontal central axis, the modiolus or columnella, around which is wound a spiral tube, in a manner similar to the spirals in certain snail shells. The modiolus has numerous canals in its interior for branches of the auditory nerve ; the largest is the canalis caitralis modioli. The spiral canal diminishes in diameter as it approaches the apex of the cochlea, makes two and one-half turns around the axis, and terminates in a closed extremity, the cupola. Projecting into the spiral canal from the modiolus is the bony lamina spiralis, which does not reach the outer wall of the cochlea. From the free border of the lamina sjjiralis or near it two membranes extend, in the natural state, the membrana basilaris and the membrane of Beissner. These two membranes are connected with the outer wall of the cochlea and inclose between them the cochlear duct, or scala media ; they are, in fact, two parts of the membranous cochlea. By the bony lamina spiralis and the two membranes just alluded to the spiral canal is divided into three parts : the scala tympani and the scala vestibuli, between which is the scala media. The scala tympani is on the basal side of the lamina spiralis, and opens into the tympaiu;m at the fenestra rotunda, though in the natural state this opening is closed by the membrana tympani secundaria. The scala vestibuli is on the opposite side of the lamina spiralis, and opens into the vestibule. These two scahe com- municate witli eacii other by an opening at the summit of the cochlea, known as the helicotrema ; thej^ contain the perilympli. The perili/inpJi is in comnumication with the subaraclinoid space of the brain along the sheatli of the auditory nerve. The Membranous Labyrinth, the earliest formed and therefore the oldest part of the organ of liearing, lies within the osseous labyrinth, from which it is separated in most places by the perilymph. It contains the endolymph and the terminations of the auditory nerve, and it is lined by epithelium. s— II— -38 PLATE CVII. Cupola Lamina spiralis Modiolus Aqueductus cochlea INTERIOR OF OSSEOUS PORTION OF COCHLEA. 484 PLATE CVIII. Lamina spiralis a vcstibuli Aqueductus cochleae Scala tympani I trmination of internal auditory meatus Modiolus Central canal of the modiolus SECTION OF OSSEOUS PORTION OF COCHLEA. 435 THE ORGAX OF HEARING. 437 In the vestibule are I'ouml two vesicles, the utricle ainl tlie saccule, the former lying partly in the fovea hemielliptica, and the latter in the fovea liemi spherica. The membranous semicircular canals open into the utricle by orifices. Filaments of the vestibular branch of the auditory nerve ai'e distributed to a thickened portion of the walls of the utricle which contains calcareous masses, the otoliths. The saccule, which is smaller than the utricle, receives branches of the auditory nerve through the perforations in the fovea hemispheriea ; as in the utricle, these nerves are distributed to a thickened portion of the wall of the cavity, which is covered with otoliths. Passing from tlie saccule along the aqueductus vestibuli is a slender tube, the ductus endolymphaticus, which expands into the saccus endolymphaticus, a blind pouch which lies on the posterior surface of the petrous portion of the temiwral bone beneath the dura mater ; this canal is joined by a small tube from the utricle, and thus the two portions of the mem- branous vestibule are brought into direct communication. The saccule communi- cates with the scala media ol" membranous labyrinth of the cochlea by means of a short tube, the canalis reuniens. The membranous semicircular canals are about one-fourth the diameter of the osseous canals in which they lie ; their extremities are ampullated. The membranous cochlea, cochlear duct, or scala media, lies between the scala tympani and scala vestibuli, as already stated. It follows the windings of the spiral tube of the cochlea, and ends blindly at both extremities, though near its basal end it communicates with the saccule by the canalis reuniens. Within the scala media is found the organ of Corti, a complex arrangement of modified epithelial cells to which the final ramifications of the cochlear branch of the audi- tory nerve are distributed. The description of the more minute structure of the internal ear is not within the province of this book, and for these details the reader is referred to works on sj^stematic anatomy and histology. Aural vertigo is indicated by ringmg in the ears or head, dizziness, reeling, and nausea and vomiting in succession. It is produced by abnormal increase of pressure in the membranous labyrinth. Cerumen or instillation of cold licpiids into the external auditory meatus may produce this symptom, and it may result from abnormal conditions in the middle ear and reflected irritation in gastric catarrh. Aural vertigo has been termed Meniere's disease. Blood Supply. — The blood supply of the internal ear is derived from the auditory artery, a branch of the basilar, which enters the internal auditory meatus with the auditory nerve, and divides into branches for the cochlea and vestibule. The veins which drain tlie internal ear are the vena aqueductus cochlea and vena aqueductus vestibuli. The vena aqueductus cochlea receives the veins of the 438 SURGICAL ANATOMY. cochlea, passes through the aqueductus cochlete, and empties into tlie internal jugular vein. The vena aqueductus vestibuli receives the veins from the vesti- ' bule and semicircular canals, and empties into the superior petrosal sinus. The Lymphatics of the Internal Ear terminate in the tympanic and intra- cranial lymphatic vessels. The Auditory Nerve is the nerve of the special sense of hearing. In the internal auditory meatus it divides into two branches, the cochlear and the vestibular ; the former is distributed to the cochlea, and the latter to the walls of the membranous vestibule and ampullse of the semicircular canals. THE MEMBRANES AND VESSELS OF THE BRAIN. The dura matei", the meningeal vessels, the sinuses of the dura mater, and the mode of exit of the cranial nerves from the cranial cavity are described in volume I, pages 568 to 599. We now resume the study of the brain, the dissec- tion of which has been facilitated by one of the processes for preserving and hardening that organ. THE ARACHNOID. The Arachnoid, the second of the three membranes of the brain, is interme- diate in position between the dura mater and the pia mater. It envelops the brain, and, like the dura mater, sends processes into the longitudinal and trans- verse fissures, between the hemispheres of the cerebellum, and, to a slight extent, into the fissure of Sylvius. It also surrounds the nerves, forming tubular sheaths for them as far as their points of exit from the skull. Unlike the pia mater, it does not dip into the sulci or fissures between the convolutions, but passes directlj- from one convolution to the other, bridging over the sulci. It forms a loose investment for the brain, and is continued downward over the sjnnal cord. Being a serous membrane, it jn-esents to the naked eye a smooth, polished surface. It is connected liy delicate coimective tissue with botli the dura mater and pia mater, but much more intimately with the lattei'. The connection between the arachnoid and the pia mater makes the inde- pendent removal of the arachnoid very difficult. The arachnoid and pia mater PLATE CIX. Posterior semicircular canal Scala media of cochlea Superior semicircular canal Ampullae Saccule Canalis reuniens Utricle Ductus endolymphaticus Ampulla F>ternal semicircular canal DIAGRAM OF MEMBRANOUS LABYRINTH, 439 THE }fF.MnRAM':s AM> VESSELS OF THE BRA IX. 441 can be separated, luiwrvrr, Ky intlatiii^- tlu> suUaracliiuiid simcc with air liy means of a lilowiiipe. The Subdural Space. — The araelnuiid was I'ormerly deseril)ed as eonsisting of two hiyers — a parietal layer, lining the inner .■'nrface of the dura mater, and a visceral layer, reflected over the Inain : in tiiis respect it was said to resemble serous membranes elsewhere. It is now regarded as consisting of but one layer. The space between the dura mater and the arachnoid is known as the subdural apace, and contains a small amount of fluid ; this space was formerly styled the cavity of the arachnoid ; it does not communicate with the subarachnoid sjmce or with the ventricles. The Subarachnoid Space. — Tiie space between the arachnoid and the jtia mater is known as the subarachnoid space ; it is most jironounced at the base of the brain. Here the arachnoid membrane is thicker than elsewhere, and bridges over the interval between the temporo-sphenoid lobes and the space between the hemispheres of the cerebellum, partially occupied by the medulla oblongata. By the intervention of tlie pons this general subarachnoid space is subdivided into the anterior and the 2^osterior space. The posterior space connnunieates with the subarachnoid space of the spinal cord and with the fourth ventricle of the brain through a small oi)ening in the r6of of the latter called the foramen of Magendie, and tln'ough two other apertures — the foramina of Kcij and Retzius — which are located at each lateral recess of the fourth ventricle. This space contains the cerebro-spinal tliiid ; l>ecause of this fact the lirain may be said to lie on a water-bed. Projecting into this space are seen the larger blood- vessels on their way toward tlie l)raiu ; the lymphatics of the Ijrain and spinal cord empty into this space, which is in connnunication with the perilymph of the internal ear and witli the lymphatics of the nose. Subarachnoid Cisterns is the name given to the more capacious i)ortions of the subarachnoid space, the largest being the cisterna magna, situated between the adjacent surfaces of the medulla oblongata and cerebellum. The cisterna magna is the upward continuation of the posterior portion of the spinal subarachnoid space. The anterior portion of the spinal subarachnoid space is continued upon the anterior surface of the medulla oblongata and pons as the cisterna pontis, and communicates freely around the medullo-pontine furrow, or sulcus, witli the cisterna magna, which is situated above and behind the medulla oblongata. The cisterna basalis is that part of the subarachnoid space situated between the ti])s of the temporo-sphenoid lobes and the crura cerebri, and in front of the pons ; into it project the circle of Willis and the vessels connected with this circle. Laterally, the cisterna basalis extends into the Sylvian fissures ; while anteriorly it extends into a minor space in front of the optic chiasm, and tiience further 442 SURGICAL ANATOMY. forward into the great longitudinal fissure. Another large space is found above the corpus callosum ; in the pia mater at the bottom of this space are the anterior cerebral arteries. Between the superior vermiform process of the cerebellum and the corpora quadrigemina is an additional space, which contains the veins of Galen. These spaces communicate very freely with one anotlier, and witli the fourth ventricle, as stated. The Cerebro-spinal Fluid is a serous fluid, Ijut, unlike ordinary serum, it is not coagulable. This fluid assists in jDrotecting the brain and spinal cord from violent shocks and vibrations. It is secreted b}' the cells of the ependyma over the fringe-like, vascular processes of the choroid plexus, and slightly hy the cells of the arachnoid. However, it is chiefly derived from the choroid plexuses of the lateral ventricles, and to a less extent from the choroid plexuses of the third and fourth ventricles. The fluid passes from the lateral ventricles to the third ventricle through the foramina of Monro, from the third to the fourth ventricle through the arpieduct of Sylvius, and from the fourth ventricle through the fora- mina of Magendie, Key, and Retzius, to the subarachnoid space of the brain and spinal cord ; some of the cerebro-spinal fluid passes directly from the fourth ven- tricle to the central canal of the spinal cord. This constitutes the course through which the cerebro-spinal fluid circulates, and equalizes the intra-cranio-spinal pressure. By exudation of plastic lymph at the base of the brain, meningitis, especially the tuljercular variety, may cause obstruction of the foramina of Magen- die, Key, and Retzius, and produce dropsy or hydrocele of the ventricles {internal hydrocephalus) ; hence, tapping of the lateral ventricles, which is sometimes prac- tised in these cases, can give but temporarj' relief Asi^iration of the subarachnoid space through the anterior fontanel or of the spinal subarachnoid space, for hydrocephalus, is followed by a similar result. The sudden removal of a large quantity of the cerebro-spinal fluid, either by tapping the lateral ventricles or by aspirating through the anterior fontanel, is not without its dangers, and has been followed by severe convulsions. The normal quantity of infra-cranial lymph varies in amount from two drams to two ounces (H. Allen). The cerebro-spinal fluid is supposed to escape from the subarachnoid space of the brain and spinal cord by way of the prolongations of the arachnoid along the cranial and spinal nerves; these extensions of the subarachnoid sjiace are in communication with the lymphatic vessels in the sheaths of those nerves, and in this manner the fluid reaches the general lymphatic system of the body. It is also supposed tliat some of the cerebro-spinal fluid escapes by way of the Pac- chionian bodies directly into the sinuses of the dura mater. Choked Disc. — In tuliercnhir or other foi'ms of inflammation of the mem- branes at the base of tlie lirain willi deposit of lymph, or in case of tumor at the PLATE ex. Anterior communicating a Antero-median ganglionic arteries Ophthalmic a Internal carotid a Anterior cerebral a. Postero-median ganglionic arteries Antero-lateral ganglionic arteries Middle cerebral a. Superior cerebellar a. rior inferior cerebellar a. Vertebral a Posterior spinal a. Anterior-spinal a Posterior inferior cerebellar a, Posterior meningeal a. J CIRCLE OF WILLIS AND ARTERIES OF BRAIN. 444 THE MEMB RAXES AXP VESSELS OF THE BRAIN. 445 base making pressure, the .sheath of the ujitic lu'ive becomes distendwl, cau-^iiig a congestion of the veins of the optic disc (choked disc), an important diagnostic sign. Pressure, liowever, does not suffice to expkiin all cases of " choked disc " ; in many cases there is distinct inflammation of the optic papilla, .so that the term papillitis would be preferable. The Lymphatics of the brain open into the subarachnoid space. The Pacchionian Bodies are enlargements of the normal villi of the arach- noid ; they project from the sui'face of tliat membrane-, and may perforate the overl3'ing dura mater and cause absorption of the bone in their vicinity. Dissection. — The next step in the dissection consists in removing the arach- noid from the base of the brain. The arteries entering the cranial cavity to supply the brain and the formation of the arterial circle of Willis are then to be carefulh' examined. THE .\RTERIES OF THE BRAIN. The Circle of Willis, which lies in the pia mater and 2:)rojects into the sub- arachnoid space, is formed liy branches of the internal carotid and basilar arteries. It forms a heptagonal figure, although it is usually not exactly symmetric. This arrangement serves to equalize the flow of blood derived from the two internal carotid arteries and the basilar artery. AVitliout this or some similar arrange- ment ligation of the common carotid, internal carotid, or vertebral artery would probably alwaj's result in softening of the brain. This circle is formed by the two posterioi- cerebral arteries, which are the terminal divisions of the basilar, the two internal carotid arteries, the two posterior communicatinfj hranrhes of the jnternal carotid arteries, which connect the latter with the posterior cerebral arteries, the two anterior cerebral arteries (branches of the internal carotid arteries), and the anterior communicating artery, a transA'erse branch which connects the ante- rior cerebral arteries. This circle is in relation with the several structures which are situated in the interpeduncular space, and form the floor of the third ventricle. The arteries which enter the cranial cavity for the supply of the brain are the two internal carotid and the two vertebral. The Internal Carotid Artery, one of the two terminal branches of the common carotid, enters the cranial cavity by Avay of the carotid canal, pierces the cartilage which fills the middle lacerated foramen, and ascends by the side of the body of tlie sphenoid bone along tiie inner wall of the cavernous sinus. Upon the inner aspect of tlie anterior clinoid process it pierces the dura mater, gives off the ophthalmic artery, and passes between the optic and oculo-motor nerves. Having reached the anterior perforated space at the inner extremity of the 446 SURGICAL ANAT03IY. fissure of Sylvius, it gives off the postei-ior communicating and the anterior choroid arteries, and divides into the anterior and middle cerebral arteries. The Anterior Cerebral Artery runs forward and inward across the anterior perforated space and the lamina cinerea, and between the optic and olfactory nerves, to reach the longitudinal fissure. Here it is joined to the anterior cerebral artery of the opposite side by a transverse branch, the anterior communicating artery. It now curves around the genu of the corpus callosum, and runs back- ward along the upper surface of the corpus 'callosum and at the bottom of the longitudinal fissure of the cerebrum as fiir as the splenium of the corpus callosum, where it anastomoses with the jiosterior cerebral artery. At its commencement the anterior cerebral artery gives off a few antero- median branches to the anterior extremity of the caudate nucleus. At the bottom of the longitudinal fissure it gives off branches to the corpus callosum, the frontal lobe, marginal gyrus, quadrate lobule, and gyrus fornicatus. The Anterior Communicating Artery, the shortest artery in the body, lies on the lamina cinerea in front of the optic commissure, and connects the two ante- rior cereliral arteries across the longitudinal fissure. It also gives off antero- median ganglionic branches which pierce the lamina cinerea, and a small branch to the anterior extremity of the corpus callosum. Sometimes this vessel is absent, when the two anterior cerebral arteries have no connection, or form a common trunk, and then divide. The Middle Cerebral Artery (Sylvian), the largest branch of the internal carotiil, runs outward deeply within the fissure of Sylvius, and supplies the motor area of the brain. It gives off branches which supply the caudate and lenticular nuclei, the internal capsule, the optic thalamus, and the surface of the brain, a^ follows : Small branches which pass through the bottom of the fissure of Sylvius to the head of the caudate nucleus ; antero-lateral branches, which pass through the anterior perforated space and supply the body and tail of the caudate nucleus, the internal capsule, and the optic thalamus ; a branch, the lenticulo- striate, wliieli passes through an aperture in the anterior perforated space and supplies the lenticular and caudate nuclei. The lenticulo-striate artery is called by Charcot the artery of cerebral hemorrhage, as it has so frequently been found ruptured in this condition. Finally, opposite the island of Reil, the middle cerebral artery gives off cortical branches which supplj^ the operculum and the teni|)()i-:il iiiid parietal lobes, especially the supra-marginal and angular gyri. The Posterior Communicating Artery arises from the posterior surface of the inti-rnal rarotid, and runs directly backward, parallel to and on the inner side of the oculo-motor nerve, to join the posterior cerebral ai'terj'. It varies in size, being sometimes so large as to give the impression that the posterior cerebral artery is its PLATE CXI, Ascending frontal a Ascending parietal a. Inferior frontal a Middle cerebral a. Parieto-temporal a. MIDDLE CEREBRAL ARTERY. 447 '/•///•; .i//;.i/y.'y,'.i.v/;.s' axd vessels of the brain. 449 contimiation. A givat (lill'orcuct' in tlie size of the vessels of the two sides is not inl'ivosterior inferior cerebellar artery. The Superior Cerebellar Arteries, one on each side, arise from the basilar so near its liifurcation as to lie .sometimes mistaken for the posterior cerebral arteries. The superior cei-ebellar artery is separated from the posterior cerebral artery by the oculo-motor nerve. The sujwrior cerebellar arteries pass outward around llu' cnirM (MTcbri, lying ni'arly parallrl with Ihi- ]iathetic nerves, antl reach the PLATE GXII, Anterior communicating a Posterior communicating a Posterior cerebral a Posterior choroid a. Anterior cerebral a. .nternal carotid a. ' Anterior choroid a. Middle cerebral a. or. of superior / cerebellar a.' External b ' lar a Superior cerebellar a Cortical branches of posterior^ cerebral a Internal br.of superior cerebellar a Basilar a Anterior spina Transverse a. Anterior inferior cerebellar a, Vertebral a. Posterior inferior cerebellar a. ARTERIES AT BASE OF 452 THE MEM HI!. WES AM) VESSELS OE THE J!J:AL\. 453 upper surface of (he cerebellum. Here they diviile iiilu branches which auaslo- U108C with the ciirresjioiiiliiig artery ol' the iip[)Osite side aiul with tlie iufci'idr cerebellar artery. The Posterior Cerebral Arteries, the two tenuiiKil l)ranches uf the basilar, wind around the erura eiTebri, and, nuining parallel with the superior cerebellar, from which they are se]>arated by the oculu-niotor nerves, reach the inner surface of the posterior part of the cerebrum. As noted, tluy aie joined to the internal carotid arteries by (he posterior comnmnicating branches of the latter vessels. The}- supply the occipital and (emporo-s})henoid lobes, and anastomose with the anterior and middle cerebral arteries. Like the anterior and middle cerebral arteries, the posterior cerebral gives off central and cortical branches. The central branches are as follows: 8niall branches which pass through the posterior perforated space to .supply (lie o^jfic thalamus and the walls of the third ventricle; tlie posterior choroid, which passes through the tran.sverse fi.ssure to reach the velum interpositum and the choroid plexus ; while odiers run to the optic (halamus, cms cerebri, and corpora quadri- gemina. The cortical branches are distributed to the adjacent parts of the tem- poral and occipital lobes. Anastomoses of Cerebral Arteries. — Between (he cortical and the central branches of (he arteries which supply the brain (here is no anastomosis ; conse- quently, these two sets of branches form two independent systems. The cortical branches, however, may and do anastomo.se with each o(her, but seldom sufficiently to nourish a p(.irtion of (he brain from which (he Ijlood current (hri:iugh (he main artery supplying it has been cut off. In odier words, (lie cen(ral vessels differ from the vessels of (he upper or lower extremity in not being able (o es(ablish a collateral circulaiion which will perform the office of the principal vessel in the event of its being .seriously disabled. In (his respect they resemble (he vessels of the lungs, kidneys, and re(ina. The central branches do not anastomose wi(h each o(her ; (herefore, obs(ruc(ion of one of the t-hief vessels- of the brain will result in softening of the region supplied by i(s cen(ral branelu-s. wliile softening of the region supplied In' its cortical branches does not necessarily follow. Peculiarities of the Arteries to the Brain. — In studying (he course of the four large ar(eries — (he two internal carotids and the two vertebrals — which enter (he cranial cavi(y (o supply (he Ijrain, (he dissecinr will v way of the transverse fissure. Both the velum interpositum and tlie chonijd ]ilexus will bo descril)ed witii the ventri- cles of the brain. Tlu; })oi-ti()iis of tlu' pia mater which cover the crura cerebri THE BRAIN. 455 and tlio pons have a (litU'rcut aiiiuaranfo from tlie rest of the menihrane, and present a dense tibrons strneture wliich contains but few vessels. Nkrve 8ri'i>Lv. — The pia mater is supplied with nerves by branehesfrom the sympatlietie, trifacial, and glosso-pharyngeal nerves. THE BRAIN. DissECTicix. — If the arachnoid and the [lia mater have been allowed to remain in place thus far, they should now be removed, witli the exception of that portion of the p*ia mater which is prolonged inward between the splenium of the corpus collosum above and the pineal gland and the corpora quadrigemina below, to form the velum interpositum which is placed between the corpus callosum and fornix above and the optic thalami, pineal gland, and corpora quadrigemina below. The removal of these membranes exposes the surface of the brain ; and in dissecting them from the base of the brain care should be taken not to detach any of the cranial nerves. Definition and Weight. — The In-ain, or encephalon, is the intracranial mass of nervous matter, or that portion of the cerebro-spinal axis which is contained within the cavity of the cranium. Its average weight in the adult male is forty- nine ami onedialf ounces, and in the female forty-four ounces. Divisions. — The brain is composed of four main jiortions : The cerebrum (large brain) ; the cerebellum (small brain), which is second in size ; the pons Varolii, which is third in size ; and the medulla oblongata, the smallest, yet physi- ologically the most important. Position of the Pons. — Of these four portions the pons Varolii is the center around which the three remaining portions are not only grouped, but to which they are connected in the following manner : To the cerebrum by the crura cerebri, the cerebellum by the crura cerel)elli (middle peduncles of the cerebel- lum), and the medulla oblongata by the anterior pyramids and part of the lateral tracts. The pons rests upon the posterior surfoce of the body of the sphenoid bone and the upper part of the basilar process of the occipital bone. Position of the Cerebrum. — The cerebrum occupies all the upper part of the cranial cavity, concealing from view the other portions of the brain when one looks from above, and rests upon the floor of the anterior and middle fossae of the skull, and the tentorium cerebelli. The tentorium cerebelli, in addition to su[)pi)rting tlie cerel)rnm, separates it from the cerebellum and jn'utects the latter fnim ]>ressure liy the cerebrum. Position of the Cerebellum. — The cerebellum occupies the space between the tentorium cerebelli and the floor of the posterior cranial fossa. 456 SURGICAL ANATOMY. Position of the Medulla Oblongata. — The medulla oblongata is continuous below with the spinal cord, and rests upon the posterior part of the basilar process of the occipital bone. Contour. — The brain is convex upon its uj^per and lateral surfaces, and irreg- ular upon the lower or liasilar surface, where it conforms to the base of the skull. The form of the surface of the brain is largely that of the interior of the cranium, but not sufficiently so as to make phrenology an exact science. Structures at the Base of the Brain. — In dissecting the brain the most suit- able article upon which to place it is an ordinary dinner plate covered with a thick layer of absorbent cotton wet with alcohol. This soft bed will jn-event the convo- lutions from being flattened when the brain is laid on its ujiper surface to study the structures forming the base. These are the inferior surfaces of the frontal and temporo-sphenoid lobes of the cerebrum, which are irregular and conform to the inequalities of the base of the .skull, this relation explaining why contusion of the cerebrum is more common at the basilar surface of these lobes than elsewhere ; the fissure of Sylvius, which separates the frontal from the temporo-sphenoid lobe ; the olfactory tracts and bulbs ; the longitudinal fissure ; the corpus callosum and its peduncles ; the anterior perforated spaces ; the optic commissure and the terminal parts of the optic tracts ; the lamina cinerea, the tuber cinereum and a part of the infundibulum — the remaining part, with the pituitarj' body, liaving lieen de- scribed ; the corpora alliicantia, or manunillary eminences ; the posterior perforated space ; the crura cerebri ; the pons Varolii ; the middle crura of the cerebellum ; the lateral hemispheres of the cerebellum ; the medulla oblongata ; the jwsterior extremity of the inferior vermiform process of the cerebellum ; and, finally, the roots of the cranial nerves. Frontal Lobes. — The inferior or orbital surfaces of the frontal lobes are trian- gular in .shape, and separated in front by the longitudinal fissure. Their bases are directed backward, and formed by the fissure of Sylvius. They pi'esent two well-pronounced sulci or fissures — the triradiate, or orbital, and the olfactory. The.se, as will be seen later, divide them into their convolutions. The Olfactory Tract and Bulb are seen occupying the olfactory sulcus. Temporal Lobes. — The inferior surface of the temporal or temporo-sphenoid lobe, is slightly convex anteriorly and concave posteriorly, and thus accommodates itself in front to tlie jiortions of the middle cranial fossa formed liy the greater wing of the sphenoid anil the anterior surface of the petrous portion of the tem- poral bone, and behind to the convex tentorium. It presents the termination of two well-])ronounced sulci — the third tem))oral and the inferior occipito-temporal. Fissure of Sylvius. — Between the iid'erior surfaces of the adjaci^nt tVontal and tcniporo-splieudid lubes is seen the fi.ssure of Sylvius, the largest of tlii.' prim- PLATE CXlll. Olfactory tract Optic n Optic tract Triradiate fissure Anterior perforated space Cfus cerebri Temporo-sphenoid lobe of cerebrum Olfactory bulb Pituitary body Optic commissure ,Tuber cinereum Corpora albicantia 3rd cranial n, 4th cranial n. , Anterior pyramid of - dulla oblongata Middle peduncle of cerebellum Posterior perforated space Pons Varolii Olivary body 6th cranial n. Decussation of pyramid Occipital lobe of cerebrum sensory root of 5th cranial n. Motor root ot 5th cranial n. . 7th cranial n. 3th cranial n. 9th cranial n. I 0th cranial n, th cranial n. 2th cranial n. BASE OF BRAIN AND SUPERFICIAL ORIGIN OF CRANIAL NERVES. 458 THE IIRAIN. 459 ary fissures of tlic ccrelnimi, tlmnigh wliidi nui.s the middle cerebral artery ; into this fissure extends the lesser wini;' ot the sphenoid hone, and from the fi(X)r of its anterior portion projeets the island of Ueil, or central lobe of the cerebrum. The Longitudinal Fissure separates the two frontal lobes, and if the cerebel- lum is lifteil, the fissure will be seen to separate completely the two occipital lobes. Corpus Callosum. — l'>y carefulh' separating the frontal lobes, the beak or rostrum of the corpus callosum will be seen in addition to two white bands, — the peduncles of the corpus callosum, — which are continued backward and outward on each side of the rostrum across the anterior perforated space to the commence- ment of the fissure of Sylvius. The Anterior Perforated Spaces, one on each side, are situated at the inner extremity of the fissure of Sylvius. Each space is triangular in shape, bounded in front by the frontal lobes and tlie roots of the olfiictory tracts, externally by the apices of the temporo-sphenoid lobes and the fissure of Sylvius, and posteriorly by the optic tract. They are crossed by the peduncles of the corpus callosum and the external olfactory root ; they transmit small vessels, chiefly branches of the middle cerebral artery, to the corpora striata, which lie immediately above the spaces. The Optic Commissure or Chiasm, from which arise the optic nerves, lies between the anterior perforated spaces and behind the anterior inferior jinrlion of tiie longitudinal fissure. It is formed by the union of the optic tracts — two white cords seen running on the outer side of the crura cerebri. The Interpeduncular or Intercrural Space is a lozenge-shaped or quadrilateral area, bounded l)y the optic commissure in front, the pons Varolii behind, and the optic tracts and the crura cerebri at the sides. It contains the tulter cinereum, the intra-dural portion of the infundibulum, the corpora albicantia, the posterior per- forated space, and the oculo-motor nerves. These structures, except the last men- tioned, form the floor of the third ventricle with the exception of its anterior part, which is formed by the structure next to be described — the lamina cinerea. Lamina Cinerea. — To expose the lamina cinerea to the best advantage, dis- place baclcward the optic commissure, above which it lies. It will then be seen to extend from the beak or rostrum of the corpus callosum, to which it is attached in front, to the tuber cinereum, to which it is attached behind. It is composed of gray matter continuous with the anterior perforated spaces. The Tuber Cinereum is a gray eminence, situated behind tlic optic commis- ,sure and in front of the corpora albicantia. It is a hollow conic process continu- ous with the infundibulum, Avhich connects the third ventricle with the pituitary body. Tlie infundibulum pierces tlie diaphragma sella?, a process of the dura mater which bridges the jiituitary fossa. The Pituitary Body (Hypophysis Cerebri) is the small body which occupies the pituitary fossa or sella turcica and is covered superiorly by the diaphragma 460 SURGICAL ANATOMY. sellffi. It is composed of an anterior and a posterior lobe whicli ditfer in size, structure, and origin. The anterior lobe is mucli the larger, is of reddish-gra^^ color, and is an isolated process of the wall of the buccal cavitj- of the embryo. The posterior lobe is tlie smaller, is lodged in a depression in the anterior lobe, is of yellowish-gray color, and is a process of the brain. It is the only j)art of the pituitary body structurally continuous with the inl'undiliulum, whieh, in passing from the floor of the third ventricle to the pituitary bod}', pierces the diaphragma sell*. The Corpora Albicantia (l)ulbs of the fornix), two knobs situated behind tlie tuber cinereum, are formed by the anterior crura of the fornix, and the bundles of Vicq d'Azyr from the oj)tic thalamus, wliicli reach the base of the brain. The Posterior Perforated Space is tiiangular in sliape, its base corresponding to the corpora albicantia ; its apex, to the pons ^"arolii ; and its sides, to the crura cerebri. It gives j^assage to postero-median ganglionic branches of the posterior cerebral and posterior communicating arteries, which run to the optic thalami. The Crura Cerebri, or cerebral peduncles, are two large cylindric masses of white and gray matter. They are about tlu'ee-fourths of an incli, or eighteen mil- limeters, long, broader in front than liehind, and composed of the longitudinal fibei's of the pons \"arolii, together with some filters from tire cerebellum. They commence at the anterior border of the jions, from which they emerge, and then pass forward and outward. They traverse the superior occipital foramen in the tentorium cerebelli in comjtany with the superior peduncles of the cerebellum, the oculo-motor and pathetic nerves, and the basilar artery, and each enters the anterior and inner aspect of the corresponding temporo-sphenoid lobe. The optic tract and the pathetic nerve pass around the outer border of the corresponding crus cerebri, while the oculo-motor nerve winds around the iimer border. Later, when making sections of the brain to study the arrangement of its interior, the crura cerebri will be cut across, wlien the locus niger, a gray nucleus in the interior of each crus, will be exposed. The nucleus separates the fibers of the crus cerebi'i into two sets: a lower and smaller — tlie cnisfn — and an upper and larger — the terpnentuvi. The Pons Varolii, or Tuber Annulare, the central figure in the group of the four divisions of the Itrain, is composed cliiefly of white matter, and is situated behind the crura cerebri, in front of the medulla oldongata, and between the hemi- spheres of the cerebellum. It is about an inch, or twenty-five millimeters, long, and n;lhcr more IIkih tliis in width ; from lis dursal to its ventral surface it measures alxiul Ihnv-ruurliis of an inch, or eighteen millimeters. It is markedly convex from side to side and slightly so from liefore liackward. and presents an antero-posterior median groove which accommodates the basilar artery. It consists princi])ally of two sets of tiber.s — a transverse, or superficial, and a longi- tudinal, or deep, set. Tlie former set extend laterally into each hemii^phere of the cerebellum, forming the middle jieduncU's, or great ti'ansverse commissure, of Till-: ('h'.WIAI. .XERVES. 461 the ceivlK'Huin ; ami the latter set cxteinl turwavd and outward and help to form the erura of the cerebrum. INIaking their exit through the sides of tiie j)ons, are the trifacial nerves. The upper surface of the pons forms a jiart of the floor of the fourth ventricle. The Medulla Oblongata, the suiallc'st of the four divisions of the brain, is the enlarged upper end of the spinal cord. It extends from the lower border of the pons, from which it is separated by a transverse groove, to the lower brain, and are more highly developed in certain of the lower animals. The olfactory 462 SURGICAL ANATOMY. nerves proper, about twenty in number, wbicb arise from the olfactory bulbs, have been divided in removing the brain from the skull. The olfactory tract arises by two so-called roots, an external and an internal. Tlie external or long root, com- posed of white matter, cro.sses the anterior perforated space to the anterior end of the hippocampal gyrus of the tem})oro-sphenoid lobe ; and the inner or mesial root, also composed of white matter, passes backward and inward to the anterior extremity of the gyrus fornicatus. Between these two diverging roots is a small triangular area of gray matter (trigonum olfactorium), which receives a few fibers from the olfactory tract ; when these fibers are conspicuous, they form what is sometimes called the middle or gray root. The tract thus formed is lodged in the olfactory sulcus of the cerebrum, and is suriviunded at the anterior extremity by a small rounded mass of gray matter, the oll'actory bulb. Tlie Second Cranial or Optic Nerve, which also represents a portion of the brain, is the nerve of vision, and arises from the optic commissure, which is formed by the union of the optic tracts. The o])tic tracts arise from the corpora geniculata, the nates of the corpora Cjuadrigemina, and tlie optic thalami. Each tract is composed of three sets of fibei's, — an outer, a middle, and an inner, — which have the following arrangement : the outer set passes directly to the optic nerve of the same side, the middle set to the optic nerve of the opposite side, and the inner set to the optic tract of the opposite side. On account of the course of the nerve-fibers from the otitic tracts to the nerves a lesion of one optic tract causes hemianopsia, or obliteration of vision in the corresponding halves of both eyes : as, for example, a lesion of the left optic tract causes loss of vision in the left half of Ijoth eyes. The Third Cranial or Oculo-motor Nerve arises superficially from a groove on the inner side of the crus cerebri, just anterior to the pons, and deeply from a nucleus in the floor of the aqueduct of Sylvius. It is a motor nerve, and supplies all the muscles of the eyeball except the superior oblique, the external rectus, and radiating fibers of the iris. The Fourth Cranial, Pathetic, or Trochlear Nerve is the smallest of the cranial nerves, and apparently arises at the outer side of the crus cerebri. Its real superficial origin is from the valve of Vieussens, or superior medullary velum, immediately behind t;he testes or posterior pair of corpora quadrigemina. The deeji origin is from a niicU'Us in the floor of the a<|ueduet of Sylvius in close rela- tion with the nucleus of the oculo-motor nerve. In the substance of the valve of Vieu.ssens it decussates with the ojiposite fourth cranial nerve. It then winds around the outer side of the crus cerebri, and appears at the base of the brain at the anterior border of the pons. It is a motor nerve, and supplies the superior obli(|ue or ti-uchlc'iris muscle. PLATE CXIV. External geniculate body Internal geniculate ^—7 Affected portion of Y retinae of both eyes Affected optic tract DIAGRAM OF OPTIC TRACTS. 463 THE VR AXIAL MiliVES. 465 The Fifth Cranial, Trigeminus, m- Trifacial Nerve, the largest of the eraiiial nerves, arises lioiu the siiles of tlie jioiis liy two roots — a larger, posterior or sen- sory root, and a smaller, anterior or motor mot. These roots can he traeed to the floor of the fourtli ventricle and to the gray matter in the lower part of the meihilla ohlongata and in tlie upper part of the spinal cord. It is the only cranial nerve which rescmhles a spinal nerve in arising by two roots, — a [losterior, or sen.sory, and an anterior, or motor, — and in having a ganglion on the poste- rior root. The trifacial is a mixed nerve. It distrilnites sensory filaments to the dura mater, \na mater, orbit, eyelids, nose, gums, teeth, tonsils, palate, sphenoid cells, etlimoid cells, frontal sinus, maxillary sinus, nasal fossae, pharynx, articulation of the lower jaw, ear, parotid gland, scalp, forehead, and face ; gustatory filaments to the anterior two-thirds of the tongue ; and motor filaments to four of the muscles of mastication — the temporal, masseter, and the external and internal pterygoids. The Sixth Cranial or Abducent Nerve arises superficially from the anterior pyramid of the medulla oblongata and the interval between the anterior pyramid and the olive, close to the lower margin of the pons. Its deep origin is from the floor of the fourth ventricle. It is a motor nerve, and supplies the external rectus muscle of the eyeball. The Seventh Cranial or Facial Nerve arises as two portions. The j^ars inter- media of Wrisliciy arises deeplj' from the forepart of the nucleus of tlie ninth cranial nerve, in the floor of the fourth ventricle. Its superficial origin is at the lower boi'der of the pons, external to the facial nerve proper and between the olivary and restiform bodies. The pars intermedia of "Wrisberg is considered a portion of the glosso-pharyngeal or ninth cranial nerve, its nucleus being continuous with that f the ninth cranial nerve. Its fibers are believed to enter the chorda tympani nerve. Thus, all of the special sensory fibers to the tongue are derived from the glosso-pharyngeal nerve. The facial nerve proper has its deep origin in the floor of the fourth ventricle, its fibers winding around the nucleus of the sixth cranial nerve. It arises superficially from the medulla oblongata in the groove between the olivary and restiform bodies. The facial is a motor nerve, its range of distri- bution is large, and its connections with other nerves are numerous. It supplies the stapedius muscle, gives oft' the chorda tympani nerve, the posterior auricular nerve, the nerve to the posterior belly of the digastric, and a branch to the stylo- hyoid muscle. In addition it supplies the muscles of expression and the bucci- nator muscle. The Eighth Cranial or Auditory Nerve, situated immediately beneath or external to the facial, is really two nerves, and ari.ses deeply from three nuclei, — Deiters', the accessory, and the chief nucleus. — which are all situated in the medulla oljlongata. From these nuclei two roots arise which embrace the restiform S— 11—30 o 466 SURGICAL ANATOMY. body, the lateral root arising principally from the; accessory nucleus, and the mesial root from the chief nucleus and Deiters' nucleus. Its superficial origin is external to that of the facial nerve — from the groove between the olivary and restiform bodies of the medulla oblongata. From the close relation between the facial and auditory nerves at their exit from the side of the medulla oblongata, they have been described as two separate portions of the seventh cranial nerve, and on account of their difference in consistency, (he facial portion was called the jiortio dura and the auditory portion the portio mollis. The auditory nerve is the nerve of the special sense of hearing, and supplies the internal ear. The lateral root is continued into the cochlear nerve, supplies the cochlea, and is the nerve of the sense of hearing. The mesial root is known as the vestibular nerve and sup- plies the vestibule and semicircular canals; it is a.?sociated with maintenance of equilibrium of the body. The Ninth Cranial or Glosso-pharyngeal Nerve arises from the floor of the fourth ventricle in common with the j)neumogastric nerve and the accessory por- tion of the spinal accessory nerve. It emerges from the same groove in tlie medulla oblongata as the facial and auditory nerves, but below them. It is distributed to the tympanum, the stylo-pharyngeus muscle, the mucous mem- brane of the pharynx, tlie tonsil, and the back of tlie tongue. The glosso-pharyn- geal is a .sensory and motor nerve, as well as the nerve of the special sense of taste, as it supplies the circumvallatc papilla; at the l.)ack of the tongue. The Tenth Cranial or Pneumogastric Nerve (nervus vagus or par vagum), the longe.st of the cranial nerves, commences within the cranium, extends through the neck and chest, and terminates in the up])cr jiart of the alidomen. It arises deeply from the floor of the fourth ventricle, and 8ni)erficially from the side of the medulla oblongata by ten or fifteen filaments, Avhich emerge from the medulla oblongata through the groove between the lateral column and the restiform body « and below the glo.sso-pharyngeal nerve. The pneumogastric nerve contains both motor and sensory fibers. It supjilics the dura mater, the external ear, the jiliarynx, tlie larynx, the esophagus, the trachea, the lung.s, the heart, and some abdominal viscera — viz., the liver and stomach. The Eleventh Cranial or Spinal Accessory Nerve consists of two portions — an upper or accessory, and a lower or spinal. Tlie accessory portion, the smaller, arises dee|)ly from the floor of the fourth ventricle in coiiimim with the niiilli and truth cranial nerves. tSupri'licially, it arises l»y fine filaments from the side of llie medulla nbldiigata bclciw tlic origin of the ])neumogastric nerve, and emerges M'itli it through the same groove. The spinal portion, the larger, arises by several filaments frnm the side of the spinal cord, between the liga- mentum denticulatum and the jiostcrior roots of the sjiinal nerves as low down as THE <'i:i;i:iinuM. 467 tlio sixth tvrvii-;il iui'\-e. It <;aiiis t'litranro t(i tlic cranial cavity liy way (if tiie I'oranu'U iiKigmini dl' tlir occipital Imiic, ami jiasscs (ivit tliiMniuii the iniilillc ciun- partnient nt' tiic jugular or posteriur lacerated Ibramen. Tii the latter situation the accessory portion leaves it to join the ganglion of the trunk of the vagus. The sjnnal accessory is a scnsori-niotor nerve, and supplies the sterno-niastoid and trapezius muscles. The Twelfth Cranial or Hypoglossal Nerve arises superficially i'roni the side of the medulla oblongata by several lilanients Avhieh emerge through tlu! groove between the anterior pyramid and the olivary body ; its deep origin is from the posterior portion of the floor of the Iburth ventricle. The filaments of this nerve are collected into two bundles which perforate the dura mater separatelv before passing through the anterior condyloid foramen, in whicli they unite to form the trunk of the nerve. The hypoglossal is a motor nerve. It supplies the extrinsic muscles of the tongue — viz., the genio-hyo-glossu.s, hyo-glossus, and the stylo- glossus. Tlrrough fibers derived from the pneumogastric and sympathetic nerves it suppHes a meningeal branch to the dura mater, and through fibers derived from the second and third cervical nerves it supplies motor branches to the geniodiyoid, sterno-hyoid, sterno-thyroid, omo-hyoid, and thyrodiyoid muscles. THE CEREBRUM. The brain is now laid on its base and the upper .surface examined. This surface is formed entirely by the cerebrum, and is seen to consist of two halves, called hemispheres, which are separated from each other in the median line liy the longitudinal fissure. This is one of the two largest fissures of the brain, the other being the horizontal fissure. The Longitudinal Fissure. — By gently separating the hemispheres the longi- tudinal fissure will be seen to reach the base of the brain both in front and behind, while the intervening portion is rendered more shallow by a transverse band of white matter, the corpus cnllomm, which may therefore be said to foi'ui its fioor. Running through the bottom of the fissure from before backward, and over the superior surface of the corpus callosum, are the anterior cerebral arteries ; this fis.sure also lodges the falx cerebri and its contained sinuses, the superior and the inferior longitudinal. The Horizontal Fissure. — The ]iosterior ends of the hemispheres of the cere- brum are separated from the cerel)ellum l)y the horizontal fissure, the dee]) central or purely intra-cerebral i)ortion of which is known as the fransverse fissvre or the fissure of Bichaf. The horizontal fissure accommodates the tentorium cerebelli and its contained simises, — the .straight, the lateral, and the superior petrosal, — while 468 SURGICAL ANATOMY. the deep portion, or the transverse fissure, transmits the pia mater into tlie interior of tlie cerebrum, Avhere that membrane forms the vekim interpositum. Convolutions and Fissures. — Tiie surfaces of the hemisplieres of tlie cerebrum are composed of convoUitions or gyri — elevations of gray matter wliich are sepa- rated by fissures or sulci. The greater the development of the hemisphere, the more numerous are tlie fissures and convolutions, as the increased depth and number of the fissures afford additional area to be covered with gray matter. In studying the fissures and convolutions from the fresh brain for the first time, that of a new-born child answers best, as the arrangement of these structures is some- what simpler and agrees better with the description of the brain given in text-books. Dissection. — Before studying the component parts of the brain by making sections, it is better carefully to study the surface anatomy of the hemispheres of the cerebrum. This entails separating the cerebrum from the remaining divisions of the brain and carrying an incision from the bottom of the longitudinal fissure through the median line of the corpus callosum and the structures in the median line of the cerebrum under the corpus callosum ; this renders it possible to ex- amine the three surfaces of each hemisphere of the cerebrum to the best advantage. To separate the cerebrum from the remainder of the brain, it is necessary to divide the crura cerebri and superior peduncles of the cerebellum, the latter being exjDOsed by lifting up the posterior lobes of the cerebrum. In order to do this, and also to obtain the best idea of the topograjjhic relations of the different parts of the brain, the dissector should have at least two good brains at his disposal. ^"ariations. — The two hemispheres of the cerebrum are not always the same in size, tlie left being usually the larger. This is supposed to be due to the fact that the blood supply of this side of the brain is more direct, as the left common carotid, and also the left subclavian artery, which gives origin to the vertebral, arise directly from the arch of the aorta. Surfaces. — Each hemisphere of the cerebrum presents three surfaces ; an ouuT, — convex or lateral, — an inner or nu-dian, and an inferior or basilar. The basilar surface rests in the anterior and middle cranial fossaj and upon the tento- rium i-crcbcUi. Arrangement of the Convolutions. — As has been noted, the surfaces of the hemispheres of the cerebrum are composed of gray matter arranged in folds, elevations, convolutions, or gyri ; these, in turn, are separated b}' furrows, fissures, valleys, or sulci varying in length, depth, and importance. As Ecker well states, the cluef nr primary coiivdhitions are like great mountain eliains whose direction lends to a region its characteristic features. The secondary folds originate by the splitting of a primary convolution into smaller ones by the forma- tion of longitudinal furrows, as secondary mountain ridges arise from the forma- THE cKHKURUM. 469 tion of longitudinal valleys. The deepest fissures, wliitii si'|i;n:ite tlie principal convolutions from oacli other, may be named the i)riniary ; those which separate the secondary ci involutions from each other, the secondary ; and, finally, the ter- tiary convnhitiniis are those little gyri which jut out into the primary fissures from the sides of the principal convolutions, and, therefore, give to tlie bottom uf the fissure a zigzag route. While the features of the principal convolutions are always arranged with considerable uniformity, numerous variations exist in the arrange- ment of the secondary and tertiary' convolutions. There are several reasons for this : one is that there are sometimes only a few secondary fissures, while in other cases there are quite a number ; again, in some cases tertiary convolutions which are ordinarily invisible come to the surface ; while in others, convolutions which are usually superficial sink deej^er ; in the former case the fissures are bridged over, and in the latter new convolutions exist in places where there usually is none. The general arrangement of the fissures and convolutions of the two hemi- s^iheres is moderately symmetric, yet slight differences always occur. The Cerebral Fissures, besides being classified as pi'imary and secondary fissures, are subdivided into complete and incomplete fissures. Complete fssures extend through almost the entire thickness of the cerebrum, thus producing eleva- tions in the lateral ventricles ; examples of such fissures are the hippocampal and portions of the collateral and calcarine fissures. Incomplete fissures are furrows of variable depth which do not cause protrusions in the ventricles. It is by means of the convolutions and fissures of the brain that tlie amount of the gray matter is greatly increased, without unduly augmenting the size of the brain ; furthermore, the pia mater is thus enormously increased in extent, because it follows the windings of the gyri and fissures, and its vessels, which supply the cortex, are enabled to break up into fine branches before penetrating the ])rain tissue. Lobes. — Tvich hemisphere of the cerebrum is incompletely divided by the deeper, and therefore the more important, of the fissures into the following parts, or lol)es : the frontal, the parietal, the temporal or temporo-sphenoid, and the occipital. In addition to these four lobes there is a fifth lobe — the central lobe, or island of Reil ; but as this projects into the bottom of the fissure of Sylvius, and can not be seen without drawing apart the sides of the latter, it will be described with the fiissures. The individual lobes are di.stinct from each other on certain surfaces only, while on other surfaces they ran into each other, and are without definite boundaries. The fissures are the landmarks which guide us in mapping out the hemispheres into districts, or lol)ei5, and also in locating the individual convolutions. Hence our fir.st task in the .study of the surfaces of the hemisplieres of the cerebrum is to locate the principal fissures. 470 SURGICAL AXATOMY. The Primary Fissures of the Cerebrum are, in the order of their impor- tance, the fissure of Rolando or the sulcus centralis, the fissure of Sylvius, and the parieto-occipit'al fissure. The fissure of Sylvius is found partly on the inferior, or basilar, and chiefly on the outer, convex, or lateral surface of the cerebrum ; the fissure of Rolando, or sulcus centralis, only on the lateral surftvce of the cerebrum ; and the parieto-occipital fissure, chiefly on the median or inner surface, and slightly on the outer surface of the cerebrum. The fissure of Sylvius, within which is lodged the lesser wing of the sphenoid bone, and through which passes the middle cerebral artery, commences on the basilar surface of the hemisphere of the cerebrum, at the anterior perforated space, in a depression called the vallecula Sylvii. Thence it extends outward to the external convex surface of the cei'ebrum, where it divides into two limbs : an ascending or vertical and a posterior or horizontal, which runs backward and upward to end in the parietal lobe. The main portion of the fissure is that which occupies the base of the brain. The ascending limb passes upward for about one inch, or twenty-five millimeters, into the frontal lobe in front of the precentral fissure, and is separated from the latter by the posterior part of the inferior or third frontal convolution, which arches around the end of the ascending limb. Immediately in advance of the ascending limb there runs forward and upward from the main portion of the fissure a third limb, the anterior limb. This limb, which is nearly of the same length as the ascending limb, runs directly forward into the substance of the inferior frontal convolution. The island of Reil, or the central lobe, is seen in the bottom of the fissure of Sylvius at the angle of separation of the ascending and horizontal limbs by draw- ing widely apart the sides of the horizontal limb of the fissure of Sylvius and lift- ing the operculum. It comprises a series of from five to seven small convolutions, surrounded by a limiting sulcus (sulcus circularis Reilii). The convolutions of this lolie are arranged so that they radiate from the apex, which looks downward and forward. A fi.ssure, the sulcus ceufralis insula:, running in about the same direction as the fissure of Rolando, divides it into an anterior and a posterior portion. Additional smaller fissures are seen between the convolutions of the island of Reil. The operculum is that portion of the hemisphere of the cerebrum formed by the basse of tlie inferior frontal convolution, the lower end of the ascending frontal and lower part of the ascending parietal convolution, and therefore immediately overhangs the island of Reil. The latter is external to the corjms striatum, and its fissures accommodate some of the branches of the middle cerebral artery. Calloso-marginal Fissure. — Before attempting to trace the course of the fissure of IJolando, examine the inner surface of the hemisphere of the cerebrum and locate a secondary fissure running above the corpus callosum. it lies midway PLATE CXV. Ascending limb of fissure of Sylvius Sinus circularis Reil Anterior limb of fissure of Sylvius Operculum (elevated) Sulcus centralis insulse Sinus circularis Reilii Frontal lobe K V ■M ! !/ Gyri operti of islancf of Reil 1 Temporal lobe (depressed) ISLAND OF REIL 471 PLATE CXVI, 'alloso Jj ffa/yinal fis Parle to- occipital flSS. Preoccipital notcf?. DIAGRAM OF LATERAL SURFACE OF CEREBRUM, 474 THE CEHEIIRUM. Alb between tlie upper surface of the latter nml ilic ujipor liordcr of the hemisphere, and terminates upon the external surfaeu of tla- hfnii.siilu re near this border and almost opposite the posterior end of the corpus callosum. This is the calloso- marginal fissure. The fissure of Rolando, or central fissure, is tln' most important of the three primary fissures of the brain, both from the surgical and descriptive standpoints. It runs through the motor area of the cortex of the cerebrum, upon which so many- operations have been performed in recent j'ears. It commences at the upper border of the hemisphere of the cerebrum just external to the longitudinal fissure and innnediately in front of the terminal part of the calloso-marginal fissure. From here it runs ol)li(]ue!y downward and forward Over the outer surface of the hemisphere at an angle with the anterior part of the longitudinal fissure of about 71.5 degrees, terminating a slight distance above the horizontal limb and about one inch, or twenty-five millimeters, behind the ascending limb of the fissure of Sylvius. The calloso-marginal fissure is very rarely bridged over by a secondary convolution, and, therefore, there should be no difficulty in locating it. The fissure of Rolando presents two more or less distinct bends, called its genua ; the superior genu, located at the junction of its middle third and upper third, has its convexity projecting backward ; the inferior genu is somewhat nearer the lower extremity of the fissure, and its convexity points forward. In proportion as the frontal lobes increase in size and the brain in general attains higher development the fissure runs more obliquely backward (Ecker). The parieto-occipital fissure, the smallest of the three primary fissures of the cerebrum, commences on the median surface of the hemisphere of the cerebrum about one and one-half inches, or thirty-seven millimeters, behind the corpus callosum. It begins on the inferior occipito-temporal surface at the junction of the apex of the lingual lobule with the isthmus of the gyrus fornicatus, and runs backward and vijiward to reach the upper border of the hemisphere; thence it runs outward and forward on the external or convex surface for about one inch, or twenty-five millimeters, and midway between the fissui'e of Rolando and the pos- terior extremitj' of the cerebrum. It is joined by a secondar}^ fissure, the calcarine, the direction of which is nearly horizontal. Tlie fissure ma}- be said to consist of two portions, a median and a lateral, found respectively on the median and external surfaces of the cerebrum. The first occipital convolution arches around the end of tlie lateral portion of the fissure. The lateral portion of the parieto- occipital fissure is not always well marked, often appearing merely as a slight indentation upon the outer or convex surface of the hemisphere, while the median portion of the fissure is uniformly well developed. The Frontal Lobe, the largest of the cerebral lobes, includes that portion of 476 SURGICAL ANATOMY. the hemisphere of the cerehruni in front of and aljove the main jiortion of llie fissure of Sylvius, and tliat portion in front of tlie fissure of Rolando; upon the inner surface it includes the corresponding portion of the liemis})here ahove the calloso-marginal fissure. There is generally no line of demai'cation between the frontal and parietal lobes upon the mesial surface of the hemisphere, but exten- sion of the fissure of Rolando into the longitudinal fissure (a condition sometimes existing) designates the posterior limit of the frontal lobe on this surface. The Parietal Lobe includes that portion of the lateral surface of the hemi- sphere of the cerebrum above the horizontal limb of the fissure of Sylvius, and a line representing the extension of the same limb backward to meet the posterior boundary of the lobe ; also behind the fissure of Rolando and in front of the lateral portion of the parieto-occipital fissure. Upon the inner surface it includes that part of the hemisphere in front of the mesial portion of the parieto-occipital fissure; it is unlimited in front on this surface for want of a line of demarcation between it and the frontal lobe, but, as previously stated, by extending the fissure of Rolando into the longitudinal fissure, its anterior superior limit would be repre- sented. The parietal lobe is only partly separated behind from the occipital lobe, by the lateral portion of the parieto-occipital fissure and the transverse occijsital fissure ; the latter is a secondary fissure which is not always present. P\om the temporo-sphenoid lobe, below, tliere is no attempt at complete separation. At tlie lower margin of the lateral .surface of the hemisphere of the cerebrum, between the occipital and temporo-sphenoid lobes, is the preoccipital notch produced by the impression of the veins which enter the lateral sinus. If a line be drawn to this notch from the extremity of the lateral portion of the parieto-occipital fissure, the upper part of this line, with the lateral portion of the fissure, will about represent the junction of the parietal and occipital lobes. The lower part of the line will represent the line of junction of the occipital and temporo- sphenoid lobes. This notch must not be confounded with another impression, sometimes described as the preoccipital notch, produced by the superior border of the petrous portion of the temporal bone (Brooks). The Occipital Lobe includes that portion of the convex surface of the hemi- sphere of the cerebrum behind the lateral portion of the jiarieto-occipital fi.ssure, and a line connecting the extremity of this fissure with the preoccipital notch. Upon the inner surface of the hemisphere it includes that part behind the mesial portion of the parieto-occipital fissure. Upon the liasilar surfoce there is no line of demarcation between it and the temporo-sphenoid lobe. The inferior surface of this lobe will l)e described with the same surface of the temporo-sphenoid, as two of the most imjinrtant secondary fissures here seen occupy both of these lobes, and extend witiiuut brcacli of (■(nitinuity from one to the other. PLATE CXVII Intraparietal fissure Superior vertical portion of intraparietal fissure Ascending parietal convolution Fissure of Rolando Ascending frontal convolution Superior occipital convolution Superior occipital fissure Transverse occipital fissure Parieto-occipllal fissure Angular gyrus Superior parietal convolution Calloso-marginal fissure Suprannarginal gyrus Su Sui Inferior frontal convolution Ascending limb of fissure'o'5 Sylvit. Fissure of Sylvius Horizontal limb of fissure of Sylvius '■ Superior temporal convolution Parallel fissure Middle temporal convolution Middle temporal fissure Inferior temporal convolutiori Cerebellum Middle occipital fissure Inferior occipital convolution Middle occipital convolution EXTERNAL SURFACE OF CEREBRUM. 477 PLATE CXVIII. Superior frontal convolution Superior frontal sulcus Middle front Inferior frontal sulcus Inferior frontal convoluti Longitudinal fissure Fissure of Rolando Ascending frontal convolution Precentral sulcus Intraparietal sulcu Inferior parietal convolutio Middle occipital sulcus Ascending parietal convolutio"rT Transverse occipital su Superior parietal convolution Superior occipital sulcus Parieto occipital fissure Inferior occipital convolution Middle occipital convolution Superior occipital convolution Calloso marginal fissure SUPERIOR SURFACE OF CEREBRUM, 480 THE CEREBRUM. 481 The Temporal (n- Temporo-sphenoid Lobe conipiisi':? tluit iioiticm of tlie lateral suffaee ol' the hemisphere of tiie eerehruiu helow the Imri/oiilal liuili v^ the fissure of Sylvius, aud a Hue represeutiuj;- its coutiuuatiou haekwanl, and in frout of tlie lower part of the Hue eouueetiug the preoceipital uoteh with the extremity of the lateral portiou of the parieto-occipital fissure. Upon the inferior surface of the cerebral hemisphere it lies immediately iK'hind the main portion of the fissure of Sylvius; it is not separated on this surface fi-om llic oecipiial lobe. A line drawn from the preoccipital notch to the isthmus of the jiyrus fornicatus marks the line of union of the tcmjioro-splienoid and occipital l(jbes (Brooks). The Island of Reil, or the hfth lobe of the cerebrum, is described with the fissure of Sylvius. The arrangement of the jirimary fissures and the boundaries of the lobes of the cerebral hemispheres having been given, the description of the secondary- fissures and convolutions naturally follows. Secondary convolutions fi('(|Uent!y bridge these secondary fissures, making it difficult to trace them. The Frontal Lobe is situated in the angle between the vertical and the horizontal j)lates of the frontal bone, and extends backward bey(.>nd the coronal suture. It is that jiortion of the hemisphere in front of the fissure of Rolando, anil above the anterior part of the horizontal liinl.) of the fissure of Sylvius. Like the cerebral hemisphei'e, it has three surfaces : a lateral or convex, an inferior or basilar, and an inner or mesial. Upon the lateral surface are three secondary fissures : the superior and the inferior frontal, the direction of which is horizontal, and the precentral or transverse, whose direction is vertical. The ascending and the anterior limbs of the fissure of Sylvius are also in relation A\itli it. The superior and inferior frontal fis-sures run parallel with the longitudinal, and the })recentral follows a course nearly parallel with that of the lower half of the fissure of Rolando. The superior frontal fissure commences a short distance in front of the fissure of Rolando, and runs forward and downward parallel with the longitudinal fissure, the gyrus included between the longitudinal fissure and superior frontal fissure being the first or .superior frontal convolution. The inferior frontal fissure usually commences in the precentral fissure, but sometimes in front of it, and runs forward and downward about midway between the superior frontal fissure and the lower liorder of the frontal lobe. Between the superior and the inferior frontal fissure lies the middle or second frontal convolu- tion, and between the inferior frontal lissure and the lower margin of the lobe the inferior frontal convolution is situated. The precentral fissure lies in front of and parallel with the fissure of S— ii-:;i 482 SURGICAL ANATOMY. Rolando ; its lower end is between the latter fissure and the ascending limb of the fissure of Sylvius. This fissure usually consists of two parts, a superior and an inferior precentral fissure, the former of M-hich is, as a rule, continuous with the superior frontal fissure, and the inferior at times with the inferior frontal fissure. The ascending frontal convolution is situated between the precentral fissure and the fissure of Rolando, and extends along the entire anterior border of the latter fissure. This convolution is continuous with the ascending parietal convolu- tion around both ends of the fissure of Rolando, immediately behind which the latter convolution is situated. The superior or first frontal convolution is continuous posteriorly with the ascending frontal, internally with the marginal, and anteriorly upon the basilar surface with the gyrus rectus and the internal and anterior orbital convolutions. The middle or second frontal convolution is continuous in front with the an- terior orbital convolution and the anterior extremities of the superior and inferior frontal convolutions. Posteriorly, it frequently bridges the precentral fissure, and joins the ascending frontal convolution. The inferior or third frontal convolution is continuous behind with the as- cending frontal convolution, and in front, upon the inferior or basilar surface, with the anterior and posterior orbital convolutions. Through the medium of the an- terior and ascending limbs of the fissure of Sylvius, both of which extend into this convolution, it is divided into three parts : namelj', that in front of the ante- rior limb, the pars orbitalis ; that between the anterior and the ascending limb, the pars triangularis (base of triangle looks upwanl) ; and that behind the ascending limb, the pars basilaris (Brooks). This convolution, as before mentioned, assists in the formation of the operculum. The inferior or orbital surface of the frontal lobe is triangular in shape ; the base, directed backward, is formed by the anterior perforated space and the main portion of the fissure of Sylvius. The apex is directed forward, and is formed by the curving of the convolutions in passing from the convex to the orbital surface. The sides are formed by the longitudinal fissure and the lower border of the hemi- sphere. On this surface are two secondary fissures, the olfactory and the orbital. The olfactory fissure runs parallel with the longitudinal fissure and a short distance external to it. It lodges the olfactory tract and bulb. The orbital or triradiate fissure is situated about the middle of the portion of this surface, which lies external to the olfactory fissure. It consists of a main portion, which is directed forward and runs nearly parallel with the olfactory fis- sure, and of two branches, one directed backward and inward, and the other outward. The gyrus rectus is situated between the olfactory and longitudinal fissures. PLATE CX!X. Posterior orbital gyrus Internal orbital gyrus Olfactory bulb Gyrus rectus \ Anterior orbital gyrus ,Triradiate fissure Island Reil Formatio reticularis at superior portion of pons Aqueduct of Sylvius Optic commissure Uncus Crus cerebri INFERIOR SURFACE OF FRONTAL LOBE. 483 THE CEREBRUM. 485 It is continuous in front with the supiTior or tirst tVdiilal convdlutidu, ami iutcr- nally witli thr inarj;inal ciinvolutidu. The internal, anterior, and posterior orbital gyri are located between the branches (tf the trinuliate fissure, and are named from their relation to the brandies of the fissure. Tliey are continuous respectively with the first, second, and third fruntal eunvnlutions. Inner surface of the frontal lobe. — Upon this surface are tertiary fissures, the chief of which runs for some distance jiarallel with the calloso-marginal fissure, and i)artly divides the convolution of this surface into two portions. The marginal gyrus lies between the calloso-marginal fi.s.sure and the upper and anterior margin of tlie liemisphere of the cerebrum. This convolution com- mences l)elow the rostrum of the corpus callosum at the anterior j)eribrated space, and extends ujiwanl and backward between the calloso-marginal fissure and tlie margin of the hemisphere, as far as a line which represents the continuation of the precentral fissure into the longitudinal fissure. It is continuous along the margin of the liemisphere with the superior or first frontal convolution. Tlie Parietal Lobe is that portion of the hemisphere situated luhiiid the fissure of Rolando, above the horizontal liml) of the fissure of Sylvius, and in front of the lateral limb of the parieto-occipital fissure. The portion of the lobe below the lateral limb of the parieto-occipital fissure and beyond the termination of the hori- zontal limb of the fissure of Sylvius is continuous with the occipital lobe l)y means of annedant gyri. The limit of the parietal lobe behind is represented by the lateral liml) of the parieto-occipital fissure, and a line previously described, which extends from the end of that fi.ssure to the preoccipital notch. It presents two surfaces, a lateral or convex, and an inner or mesial. Upon the lateral surface one and sometimes two chief secondary fissures are to be seen. When but one fissure is present, it is the intra-parietal, and wlien two fissures are present, tliey are tlie intra-parietal and the post-central. The intra-parietal fissure commences above the horizontal limb of the fissure of Sylvius, a short distance Ixdiind the fii5.sure of Rolando, and runs upward, parallel to the lower portion of the latter fissure ; it then turns backward, runs nearly parallel with the longitudinal fissure, and terminates in the occipital lobe, most commonly in the transverse occipital fissure. The posterior portion of the horizontal part of the intra-pai'ietal fissure is often separated from the main fissure by a bridging convolution. The post-central fissure, when [iresent, exists either as a continuation of the ascending liml> of the intra-parietal fissure beyond the junction of the ascending with the horizontal limb, thus making the intra-parietal fi.ssure T sha))ed, or it is entirely .separated from the ascending limb of the intraparietal fissure. The 486 SURGICAL AXATOMY. former is the arrangement more coiuinonly seen. The post-central fissure runs parallel to the upper portion of the hssure of Rolando almost to the longitudinal fissure. Convolutions. — Through the medii'im of the intra-parietal fissure or of the intra-parietal and po.st-central fissures the lateral surface of the parietal lobe is divided into three principal convolutions : the ascending parietal or po.st-central, the superior parietal, and the inferior parietal. The inferior parietal convolution is further subdivided into the supra-marginal and angular convolutions. The ascending parietal or post-central convolution lies immediately behind the fissure of Rolando, in front of the ascending limb of the intra-parietal fissure, and the po.st-central fissure when present, and above the horizontal lind> of the fissure of Sylvius. It is continuous -with tlie ascending frontal convolution around the ends of the fissure of Rolando, and with the superior parietal convolution. It runs parallel with the ascending frontal convolution ; its lower extremity extends to the horizontal limb of the fissure of Sylvius, forming the posterior part of the operculum ; its upper extremity is limited by the longitudinal fissure, and, with the corresponding end of the ascending frontal convolution, forms the para- central lobule. The superior parietal convolution lies behind the ascending parietal con- volution, with which it is continuous. It is situated between the longitudinal fissure and the horizontal limb of the intra-parietal fissure, and extends i^steriorly as far as the lateral portion of the parieto-occipital fissure. Around the extremity of this fissure it is continuous with the first occipital convolution through the medium of the first annectant gyrus. On the mesial aspect of the hemisphere it is continuous with the quadrate lobule or precuneus. The inferior parietal convolution lies behind the ascending limb and below the horizontal limb of the intra-parietal fissure, and above the horizontal limb of the fissure of Sylvius. Posteriorly it is connected with the second occipital convo- lutiiin by means of the second and tliird annectant gyri, and also witli the supe- rior temporal and the middle temporal convolution. It is sub(,'twrrii tlio Idii.nitudinal ami su|ii_rinr occipital fissures, and (■oiiiiiu'iu-cs at IIk,' postcriur end of llie siiperiur jiaiiital convolution, to wliicli it is eonuectcd hy the lirst unnectant gyrus. It then winds around the extremity of tlie lateral liniK of the parieto-oceipitul and tlie mesial end of the transverse occipital fissure, wluu present, and becomes continuous with the euneus, a wcdg-e-shaped lobule seen upon the inner surface of the lobe. The middle occipital convolution lies between the superior and middle occipital fissures, and eonnnt'uees at the outer side of the intra-parictal fissure, and behind the angular gyrus, ti> which it is et)nnected l)y the second and tliinl annectant gyri. The inferior occipital convolution lies between the middle and inferior occipi- tal fissures, and is connected to the inferior or third temporo-sphenoid convolution by the fourth annectant gyrus. Upon the inner surface of the occipital lobe there is but one secondary fissure, the calcarine, and one lobule, the euneus. The calcarine fissure commences, usually, by two branches close to the lower border of the posterior extremity of tlie hemisphere of the cerebrum, runs almost horizontally forward along the margin formed by the median and basilar surfaces of the hemisphere, and joins the parieto-occipital fissure at an acute angle behind and below the posterior extremity of the corpus callosum. Tliis fissure gives rise to a prominence, the calcar avis or hippocampus minor, seen in the posterior horn of tlie lateral ventricle. The euneus is a triangular lobule situated between the median limb or main portion of the parieto-occipital fissure and the calcarine fissure. Its base is directed upward and Itackward, and is formed by the inner border of the superior occipital convolution ; its apex is directed downward and forward, and corresponds to the angle of union of the calcarine and parieto-occipital fissures. The fissures and convolutions of the basilar surface of the occipital lobe are uninterruptedly continuous with those of the corresponding surface of the temporo- sphenoid lobe, and therefore the inferior surface of these two lobes will }><• studied as the lower occipito-temiroral surface. The Temporal or Temporo-sphenoid Lobe is that part of the hemisphere of the cerebrum which extends into the middle cranial fossa, its po.sterior portion resting upon the tentorium cerebelli. It lies liehind the commencement of the basilar or main portion of the fissure of Sylvius, in front of a line drawn over the lateral surface of the hemisphere of the cerebrum from the extremity of the lateral limb of the parieto-occipital fissure to the preoccipital notch, and below the horizontal limb of the fissure of Sylvius and a line representing its continuation 492 SURGICAL ANATOMY. backward. The posterior portion of this lobe is continuous with the parietal and occipital lobes, as mentioned under the description of those lobes. Surfaces. — The teniporo-sphenoid lobe presents an external, lateral or convex and an inferior or basilar surface. In addition some anatomists describe an upper or Sylvian surlace in relation with the horizontal lindi of the fissure of Sylvius. Upon the lateral surface are three secondary fissures which run horizon- tally : the superior temporo-sphenoid or parallel fissure, the middle tem])oro- sphenoid, and the inferior temporo-sphenoid fissure. Of these fissures, the supe- rior temporo-sphenoid or parallel is the most constant, and lies entirely on the lateral surface, while the middle and the inferior are mucli more varial)le. They are seldom developed with equal clearness, and are frequently interrupted and bridged by convolutions. The middle temporo-sphenoid fissure lies almost entirely on the lateral surface, while the greater part of the inferior temjioso-sphcnoid fissure is on the liasilar surface. The superior temporo-sphenoid or parallel fissure commences near the ante- rior extremity or apex of the lobe. It then runs backward and upward, parallel with the horizontal limb of the fissure of Sylvius, — hence the name of parallel fissure, — and terminates in the inferior parietal convolution, its posterior extremity being surrottnded by the angular convolution. The middle temporo-sphenoid fissure commences on the basilar surface of the lobe, and runs upward and backward, parallel with the superior temporo-sphenoid fissure. It terminates in the inferior parietal conlution, its posterior extremity being surrounded l)y the post-parietal convolution. The inferior temporo-sphenoid fissure lies in great part on the basilar sur- face, near the margin of the hemisphere, and terminates posteriorly on the lateral surface ; it separates the inferior temporo-sphenoid convolution from the lateral occipito-temporal convolution or fusiform lobule. Convolutions. — Through the medium of the superior, middle, and inferior temporo-sphenoid fissures the lateral surface of the temporo-sphenoid lobe is div- ided into three convolutions : the superior temporo-sphenoid, the middle temporo- sphenoid, and the inferior temporo-sphenoid convolution. The superior temporo-sphenoid or infra-marginal convolution lies between the horizontal limb of the fissure of Sylvius and the parallel fissure ; it is continu- ous at its posterior part with the supra-marginal and angular convolutions. The middle temporo-sphenoid convolution lies between the jiarallel fissure and the middle temporo-.sphenoid fissure, being clearly marked otf above bj' the parallel fissure. Its lower boundary is by no means so coniBtantly well marked, and it is frequently continuous with tlie inferior temporo-sphenoid convolution. It is continuous posteridrly with the angular convolution. PLATE CXXI, Collateral fissure Fusiform lobule Uncus inferior temporosphenoid fissure Superior temporo-sphenoid fissure Hippocampal fissure Hiopocampal convolution Optic commissure Crus cerebri Isthmus Parieto-occipital fissure Lingual lobule Cuneus — - Calcarine fissure- Superior temporo-sphenoid gyrus ddle temporo-sphenoid gyrus Middle temporo-sphenoid fissure Inferior temporo-sphenoid gyrus INFERIOR SURFACE OF OCCIPITAL AND TEMPORAL LOBES. 4S)4 THE CEREliinM. 495 Tlu> inferior temporo-sphenoid convolution lies along llir lnt(i:il luaruin df tlie Iii'inisiilK'n', lu'twi'i'ii the miilillc tcinporo-i^plienoid fissure and the iiiferidr U'liqioro- sphenoitl lissure ; it passes above tlie preoceipital notcli, and is continuous beliind witli the third occipital convolution. Upon the basilar surface of the lobe it is continuous with the external occipito-temporal convolvition, or fusiform lobule. The upper or Sylvian surface of the temporo-sphenoid lobe is in contact with the operculum, and intimately related to the island of Reil ; it ])res('nts two oi- tlu'ee transverse convolutions. The fissures and convolutions presenting on the basilar surface being continu- ous with those of the occipital lobe, they will be described as part of the lower occipito-temporal surface. Collateral fissure. — The basilar surface of the temporo-sphenoid lol)e contains the greater portion of the inferior temporo-sphenoid fissure, as previously described. That portion of this sui'face which is coi'itinuous with the occipital lobe, and designated as the lower occipito-temporal surface, presents a constant and impor- tant secondary fissure, the inferior occipito-temporal or collateral fissure. This commences at the posterior extremity of the oecijiital lobe ; thence it runs forward j>arallel to and boluw the calcarine fissure, nearly to the apex of the temporo- sphenoid lobe, extending almost as far as the commencement of the Sylvian fissure. It is sometimes bridged over by a secondary convolution. It produces the eminentia collateralis, a prominence in the floor of the descending cornu of the lateral ventricle, seen at the point of divergence of the middle and posterior cornua of the A^entricle. Through the medium of the collateral and hiiiiiocampal fissures the lower occipito-temporal .surface is divided into three convolutions : the fusiform lo))ule, the lingual lolmle, and tlu' hippocampal or uncinate convolution. The hippocampal convolution and the lingual kiljule are Imt portions of the internal or mesial occipito-temporal convolution. The lingual lobule lies between the collateral fissure on the outer side, and the calcarine fissure on the inner side. It occupies chiefly the occipital part of the lower oceii>ito-temporal surface. It is wide behiml and narrow in front. Till' hippocampal or uncinate convolution lies between the collateral fissure on the outer side and the hippocampal on the inner side. It is formed by the union of the isthmus or posterior continuation of the gyrus fornicatus with the lingual lobule at the anterior extremity of the mesial limb of the parieto-occipital fissure. It continues forwanl, ))ordering the hippocampal fissure and embracing the crura cerebri, to terminate innnediately behind the anterior perforated space by turning upward and backward upon itself in the uncvs. The external or lateral occipito-temporal convolution, or fusiform lobule, lies between the collateral fissure on the inner side, and the inferior temporo- 496 SURGICAL ANATOMY. sphenoid fissure, when present, on the outer side. When the inferior temporo- sphenoid fissure is wanting or is incomplete, the lateral boundary of this convolu- tion is indistinct. It extends from the apex of the temporo-sphenoid lobe to the posterior extremity of the occipital lobe. The hippocampal or dentate fissure, i)rcviously mentioned as being bordered by the hippocampal convolution, correspontls to the lateral portion of the tran.s- verse fissure of Bichat. It is situated in front of the calcarine fissure, between the crura cerebri and the hippocampal convolution, and extends outward, downward, and forward from the splenium of the corpus callosum to the uncus. It produces the cornu Ammonis or hippocampus major, a }ironnnence forming part of the inner wall of the middle cornu of the lateral ventricle. By drawing the hippo- campal convolution away from the crus cereljri, thus widening the hippocampal fissure, there will be seen a band of gray matter which reaches from the splenium of the corpus callosum to tlie uncus. This is the free edge of the hippocampal convolution, and its notched appearance is produced by the clioroid arteries, which pass through the fissure with the pia mater into the descending horn of the lateral ventricle ; this gray matter is known as the fascia dcntata, or the dentate convolution. The remaining fissures seen on the inner surface of the hemisphere of the cerebrum are the calloso-marginal and the callosal fissure, and the remaining convolution is the gyrus fornicatus. The calloso-marginal fissure, the terminal portion of which was mentioned when describing the location, of the fissure of Rolando, connnences below the rostrum of the corpus callosum, curves forward around the genu, and backward above the body of the corpus callosum. It runs about midwav between tlie corpus callosum and the u]iper border of the hemisphere to a point opposite the splenium of the corpus callosum, where it turns ui)\vard and slightly backward to terminate on the upper border of the hemisphere of the cerebrum, immediately behind the connnencement of the fissure of Rolando. From the point where the fissure turns u})ward to reach the margin of the hemisphere thei'e is fret|uently found, following the original direction of the calloso-marginal, a small fissure which separates the quadrate lobule from the gyrus fornicatus. This, under the name of the subparietal fissure, is a liranch of the calloso-marginal, as is also the paracentral fissure. The calloso-marginal fissure is not infre(|ueiitly bridged over in places by secondary convolutions which connect the marginal gyrus with the gyrus fornicatus. The callosal fissure, or ventricle of the corpus cailostnn, connnences below the rostrum, follow.s the superior surface of the corpus callosum, and terminates l)chind the sjilcnium of the corpus callosum in the hippocampal fissure. PLATE CXXll. Paracentral lobule. Tegmentum of crus cerebri Paracentral fissure Fornix Calloso-marginal fissure Fifth ventricle Gyrus fornicatus Genu of corpus callosum Marginal convolution Locus niger ,Crusta of crus cerebri Velum intetpositum allosal fissure Splenium of corpus callosum Sub-parietal fissure Quadrate lobule CuneuS' Internal orbital gyrus Anterior orbital gyrus Triradiate fissure' Posterior orbital gyrus Calcarine fissure Lingual lobule Parieto-occipital fissure Collateral fissure Isthmus Fusiform lobule inferior temporo-sphenoid ficsure Hippocampal fissure Hippocampal convolution Gyrus rectu Olfactory sulcus' Rostrum of corpus callosum Uncus Optic thalamus Lateral ventricle 11—3-2 MEDIAN AND INFERIOR SURFACES OF CEREBRUM. 497 CRAMO-VKREBHAL TOPOGRAPHY. 499 The gyrus fornicatus lies between the calloso-raarginal fissure ami the eallo- sal fissure. It commences in trout of the anterior perforated space, between tlie rostrum of the corpus callosuni and the marginal convolution, follows the super- ficial surface of the corpus callosuni, and terminates below the splenium of the corpus callosum in a narrow extremity, the isthmus, which joins the hippocampal convdlution. The Limbic Lobe includes a munber of convolutions arranged in a ring-like manner ; some of the parts are quite rudimentary in the human brain, and are the lepresentatives of more highly developed structures in some of the lower animals. The limbic lobe is made up of the gyrus fornicatus, hippocampal gyrus, the rudi- mentary gyrus supra-callosus of Zuckerkandl (formed by the peduncles of the corpus callosum, fascia dentata, and the longitudinal strice on the upper surface of the corpus callosum), together with half of the fornix and the corresponding lamina of the septum lucidum. This lobe is bounded bv the calloso-marginal and collateral fissures, and each extremity of it is continuous with one of the roots of the olfoctory tract. CRANIO-CEREBRAL TOPOGRAPHY. Sensory and Motor Areas. — Having completed the study of the fissures, the lobes, and the convolutions of the hemisphere of the cerebrum, consider the func- tions of the convolutions in certain areas of the surfaces of the cerebrum before commencing the dissection of that part of the l)rain. The two principal regions of the hemisphere are the motor area and the sensory area. The motor area com- prises the posterior ends of the superior, middle, and inferior frontal convolutions, the ascending frontal convolution, the ascending parietal convolution, and the adjoining part of the superior parietal convolution. The sensory area of the surfiice of the cerebrum has been imperfectly outlined on account of the greater difficulty attending its localization. The Silent Region. — The anterior two-thirds of the superior, middle, and inferior frontal convolutions, or that portion of the frontal lobe which practically lies in advance of the coronal suture with the brain in its natural position, is the prefrontal or silent region of the brain, where, if a lesion be present, it does not give rise to any localizing symptoms. The author has frequently seen the prefrontal region severely injured in gunshot wounds with entire absence of any paralytic symptoms. He has also seen cases of abscess of this region with similar absence of any localizing symptoms. One case in particular in his experience was that of a large abscess of the left prefrontal region, which followed a punctured fracture of the cril)riform plate of the ethmoid bone. The patient was a boy, M'ho, while playing with a hoisted umbrella, threw it up in the air. In its descent it turned, 500 SURGICAL ANATOMY. and a portion of one of the ribs passed into his left nostril and penetrated the cranial cavity, fracturing the cribriform plate of the ethmoid bone, tearing through the dura mater, and finally entering the frontal lobe. A brain abscess developed — so considered at the time and afterward proved Ity autopsy. The collection occupied the left prefrontal lobe, and at no time in the course of the disease were there any localizing symptoms. The function over which this region of the Vjrain is believed to preside is that of the higher mental faculties, and in di.sease or injury of this region, particularly upon the left side, there is very apt to be more or less hebetude, dullness of intellect, and lack of self-control. Motor Centers. — The motor area embraces the centers which preside over the movements of the opposite side of the body, and is conveniently divided into thirds — an upper, a middle, and a lower. The upper third includes the centers which control the movements of the muscles of the lower extremity ; the middle third, the centers which control the movements of the muscles of the upper extremity ; and the lower third, the centers which control the movements of the muscles of the face, the mouth, and the tongue. It would seem from recent investigation tliat the centers for tactile sensation are located in the same area as that occupied by the motor centers, for some loss of tactile sense may accompany motor paralysis ; hence the centers about to be described are at times referred to as the sensori-motor areas. There is some evidence in favor of locating the centers for muscular sense in the region just posterior to the motor area, in the neighbor- hood of the great longitudinal fissure. The following is a detailed description of the location of the individual centers of the motor and sensory areas (Ferrier) : The centers which control the movements of the opposite leg and foot, such as are concerned, for example, in walking, are situated in the anterior part of the supe- rior parietal convolution, at its junction with the ascending parietal, in the paracentral lobule and part of the quadrate lobule. The upper part of the ascending frontal convolution with the neighboring part of the base of the superior frontal convolution include the centers which control the various complex move- ments of the arms and legs, such as climbing, swimming, etc. The posterior third of the superior frontal convolution anterior to the junction of its base with the ascending frontal includes the centers for the forward extension of the arm and hand, as in reaching forth the hand to touch something in front. The upper part of the middle third of the ascending frontal convolution includes the centers for those movements of the hand and forearm which call into action the biceps, as supination of the hand and flexion of the forearm. The ascending frontal convolution, at aliout the junction of its middle and lower thirds, includes the centers wiiich control the action of the elevators and depressors of the angle of the mouth. PLATE CXXlll, Centers for (i) Opposite leg and foot, as m walking (2) Arms and legs, as in clinnbing or swimming. (3) Forward extension of arm and hand. (4) Supination of hand and flexion of forearm. {5) Elevators and depressors of angle of mouth. (6) Lips and tongue In talking {7) Platysma myoides muscle. (8) Lateral movement of head and eyes, elevation of eyelids, and dilatation of pupil. (9) Movement of fingers and wrist. (10) Vision. (11) Hearing. MOTOR ANO SENSORY AREAS OF CEREBRUM (AFTER FERRIER). 501 ii CRAMo-cEiiKiii:. I /, 'mp()<;i;. inn: 503 The base of the third frontal convohition ami, to a slight (Icgrw, tlir Iciwii- 011(1 of tlie ascending frontal and asa'nding parii'lal convolutions include the centers for the movements of the lips and tongue in talking. This region is known as Bwca's region, disease of which on the left side causes aphasia, or loss of the power of speech. The speech center, however, is not always in the left side of the brain. In leftdianded persons it is located, as has been demonstrated clini- cally, in the base of the right third frontal convolution. Aphasia is of two varieties, the motor or ataxic, and the sensory or amnesic. In the motor variety there is inability to pro|)erly coordinate the muscles presiding over articulation, while in the sensory variety there is loss of memory for words. The .speech center is connected with the centers of hearing and vision through llu; medium of the associating fibers of the cerebrum, and also, through the medium of the speech tract, with the centers in the medulla oblongata which give origin to the nerves which are employed in speech. Oidy through this connection between the speech center, the centers of hearing, and the centers of vision can the two forms of sensory aphasia — namely, word-deafness and word-blindness — be understood. The ability to write is, as a rule, lost in cases of destruction of the motor area for speech. The lower third of the ascending parietal convolution, at its junction with the inferior parietal, includes the center which controls the movements of the platysma myoides muscle in bringing about retraction of the angle of the mouth. The base of the middle frontal convolution includes the center for lateral movements of the head and eyes, with elevation of the ej-elids and dilatation of the pupil. The middle third of the ascending parietal convolution includes the centers for the movements of the fingers and wrist. The cortical centers for the different muscles and limbs overlap to a certain extent, so that while there is a more or less distinct focus of representation for a given set of muscles, adjacent parts of the cortex are also concerned in governing the muscles presided over by the focus ; hence total paralysis does not necessarily follow removal of a limited area of the cortex of the cerebrum. The supra-marginal and angular convolutions, in addition to the occipital lobe, include the centers of vision ; these, taken together, have been termed by Ferrier the occipito-angular region. The posterior part of the superior temporo- sphenoid convolution includes the centers of hearing. The anterior extremitj' of tlie hippocampal convolution or uncus includes the center of smell, while in close proximity to the center of smell is the center of taste. The convolution of tht? corpus callosum and the posterior part of the hippocampal convolution include the center of touch. Each occipital lobe receives visual impulses from one-half of both retinae, so 504 SURGICAL ANATOMY. that a unilateral cerebral lesion may produce what is known as licmianopnia, a symmetric defect in the field of vision of the two eyes. Disease of the Cortex of the Cerebrum. — Irritation of the motor area, as by a small meningeal hemorrhage, meningitis, or the application of a weak Faradic current, causes twitching or convulsive movements of the muscles of the oj)posite side. When the motor area is destroyed by disease or injury, there is complete paralysis of motion of the opposite side. If both the motor and the sensory areas are involved in the jiathologic process, both sensation and motion of the ojjposite side will be affected. In trephining for focal, or Jacksonian, epilepsj^ it is customary when the brain cortex lias been exposed to appl}' a weak Faradic current to that portion believed to include the centers wliich are concerned in the initial convulsive seizure ; in other words, the convulsive movements which the patient exhibited during the attacks are reproduced by the application of the current. In this manner the different centers presiding over the various movements of the opposite side can be located. "\Mien the affected centers have been definitely located, the entire thickness of the gray matter in the affected area is excised. This naturally results in })aralysis of the parts over whose motion they have heretofore presided. The arrest of any bleeding and closing and dressing the wound complete the operation. It is hardly necessary to say that if a lesion such as an enlarged Pacchionian bod)-, a cyst, a cicatrix, or a neoplasm is found, it should be excised. This operation demonstrates, therefore, the effect of both irritation and destruction of the motor area. In following up the cases of Jacksonian epilepsy treated by operation, it is interesting to note that the paralysis which follows the excision of the cortex diminishes, after a time, to such an extent as to permit of a return of the convulsions. The.se operations, therefore, afford but temporary relief in the great majority of cases. The return of function occurs through the compensatory action of the neighboring cells. Abolition of the function of certain groups of centers in the motor area of the cortex cerebri results in one or other of the following varieties of paralysis : If of the arm and leg, it is called brachio-crui'al paralysis, or hemiplegia ; if of the leg alone, crural monoplegia ; if of the arm alone, brachial monoplegia ; and if of the face alone, facial monoplegia. Facial monoplegia seldom occurs alone, and is most commonly associated with aphasia, owing to the close proximity of the facial and speech centers. The centers of hearing, vision, smell, and taste may be irritated by various lesion.s, so that hallucinations of these senses may, like motor disturbances, arise from irritation of the motor cortex. Thus, the so-called sensory equivalent of a Jacksonian convulsion is produced, and from the character of this attack deduc- tions as to the location of the lesion may be drawn. PLATE CXXIV. Breg LINES FOR FISSURES, LOWER LEVEL OF CEREBRUM. 506 CRAXIO-fEREBUM. Tol'Od h'A I'lIY. 507 DissKCTiON. — Shave the scalp uiion one side of the lu-ad, and uiiuii the other, turn its entire thickness down in one Hap. Uj)on tliat side where the skull wall is exposed remove half of the calvaria with a saw or a cliisel and mallet. Next reflect the dura mater in one tiap and dissect off' tlie araclnioid and pia mater to expose the fissures and convolutions. A familiarity with certain of the cranial lamlmai-ks is essential in the study of cranio-cerebral topography. These include the glal)ella (a point between the eyebrows), the frontal eminence, the external angular process of the frontal bone, the zygomatic arch, the preauricular fossa (tlie depression in front of the tragus on a level with the upper border of the external auditory meatu.s), the external auditory meatus, the mastoid process, the parietal eminence, and the external occipital jirotuberance or iniou. The Lower Level of the Cerebrum. — A line drawn horizontally across the forehead through the upper part of the glabella approximately corresponds to the lower level of the cerebrum in front. A line drawn from the external angular process of the frontal bone through the preatiricular fossa to the external occipital protuberance approximately corresponds to the lower level of the cerebrum at the sides and behind. The cerebellum lies below that portion of the last-mentioned line included between the posterior border of the mastoid process and the inion. Longitudinal and Transverse Fissures. — A line drawn from the glabella over the vertex and along the median line to the inion corresponds to the jiosition of the longitudinal fissure. A line drawn from the inion along the superior curved line of the occipital bone to a point an inch, or 2.5 centimeters, above the external auditory meatus corresponds to the position of the transverse fissure. Fissure of Sylvius. — To indicate the position of the fissure of Sylvius, draw a line from a point one and one-fourth inches, or three centimeters, behind the external angular process of the frontal bone to a point three-fourths of an inch, or two centimeters, below the most prominent part of the parietal eminence. The first three-fourths of an inch, or two centimeters, of the line represent the main fissure ; and the remainder of the line, the horizontal lind> of the fissure. The a.scending limb of the fissure is represented by drawing a line one inch, or 2.5 centimeters, in length vertically upward from the point of termination of the main fissure — that is, three-fourths of an inch, or two centimeters, from its commence- ment, or five centimeters behind the external angular process of the frontal bone. Reid's base line is drawn from the lower border of the orliit thi-ough the center of the external auditory meatus. This line is of assistance in locating the fissure of Rolando. Fissure of Rolando. — To represent the position of the fi.ssure of Rolando, first draw two perpendicular lines from the base line to the line representing the 508 SURGICAL ANATOMY. position of the great longitudinal fissure. The anterior of these passes througli the preauricular fossa, and the posterior passes along the posterior border of the mastoid process. From the point of intersection of the posterior perpendicular line with that of tlie great longitudinal fissure to the point of intersection of tlie ante- rior jjerpendicular line witli that of the liorizontal linil) of the fissure of Sylvius, draw a third line, which represents the position of the fissure of Rolando. The fissure of Rolando maj' also be located by drawing a line downward, outward, and forward from a point one-lialf of an inch, or one centimeter, behind a point mid- way between the glabella and inion and at an angle of 71.5 degrees with the anterior portion of the line for the longitudinal fis.sure. The angle formed by the fissure of Rolando and tlie anterior portion of the longitudinal fissure varies, but. in any instance, the line for the fis.sure is merely an approximate guide. The fissure measures about three and three-eighth inches, or eight and one-half centi- meters, in length. Upon each side of and running parallel with the fissure of Rolando are the ascending frontal and ascending parietal convolutions, each of which occupies a space about three-fourths of an incli, or two centimeters, in width. Parieto-occipital fissure. — Extend the line indicating the horizontal limb of the fissure of iSylvius backward to that of the longitudinal fis.sure, and the lateral limb of the parieto-occipital fissure will be represented hy about the posterior inch, or 2.5 centimeters, of tins line. The lateral portion of the parieto-occipital fissure is also found from tlirce to three and one-half inches, or eight to nine centimeters, above the external occipital protuberance. Frontal Lobe. — Through the medium of the lines indicating the course of the primary fissures of the hemisphere the lolies are mapped out. The frontal lobe lies external to the line of the longitudinal fi.s.sure, in front of the line of the fissure of Rolando, and above the lines for tlie lower level of the cerebrum and for the main and horizontal limbs of the fissure of Sylvius. The course of the secondary fissures and the position of the convolutions of this lobe will be repre- sented by the following lines: A line drawn from the supra-orbital notch back- ward and parallel Avith the line of the longitudinal fissure to within about three- fourths of an inch, or two centimeters, of the line of the fissure of Rolando indicates the course of the superior frontal sulcus. A line drawn from the external annular process of tlie frontal lione upward and l)ackward along the temporal ridge to witliin about three-fourths of an inch, or two centimeters, of the line of the fissure of Rolando indicates the course of the inferior frontal fissure. A line drawn three-fourtii.s of an inch, or two centimeters, in front of, and parallel with, the lower two-thirds of the line of the fissure of Rolando indicates, approxi- mately, the course of tlie precentral fissure. The .sujierior frontal convolution CRAXIO-CERKBRM. TOPOGRAPHY. 509 corresponds to the intiTval between tlie lines of tlic loni^itudiiial and sniieiicir frontal tissures. The middle frontal convolution corresponds to tlie intn-val between the lines of the superior and inferior frontal fissures. 'i'iie inferior frontal convolution corresponds to the interval between the line of tin- inferior frontal fissure and the lines representing the fissure of Sylvius and the lower level of the cerebrum in front. The ascending frontal convolution corresponds to the interval between the lines of the fissure of Rolando and the preeentral lissure. The Parietal Lobe lies between the lines of the longitudinal fissure and the horizontal lindi of the lissure of Sylvius, and between the line of the fissure of Rolando and that of the lateral limb of the parieto-occipital fissure. The boundary between the parietal and occipital lobes is indicated aiiproximately by a line drawn from the lateral lindj of the parieto-occipital fissure to the posterior border of the base of the mastoid process. The course of the intra-parietal fissure and the position of the convolutions of the parietal lobe are represented as follows : To indicate the course of the intra-parietal fissure, draw from a point one-half of an inch, or one centimeter, external to the end of the lateral limb of the parieto- occipital fissure to a point three-fourths of an inch, or two centimeters, behind the lower end of the fis.sure of Rolando, a line which is convex forward ; the lower third of the line sliould run parallel with the fi.ssure of Rolando. The interval bounded by this line and the lines of the fissures of Rolando, tlie longi- tudinal fissure, and the lateral liml) of the parieto-occipital fi.ssure will correspond to the ascending and superior parietal convolutions. The ascending parietal con- volution runs parallel with the line of the fis.sure of Rolando, and corresponds to the space directly behind it to the extent of three-fourths of an inch, or two centi- meters, while the remaining portion of the space included in the above boundaries corresponds to the superior parietal convolution. The inferior parietal convolu- tion, including the supra-marginal and angular gyri, corresponds to the interval bounded by the line of the intra-parietal fissure, that of the horizontal limb of the fissure of Sylvius, and the line drawn from the lateral limb of the parieto-occipital fissure to the posterior margin of the base of the mastoid process. The supra- marginal gyrus lies under the most prominent part of the parietal eminence. The Occipital Lobe lies behind the line drawn from the lateral limb of the parieto-occipital fissure to the posterior margin of the base of the mastoid process. The Temporal or Temporo-sphenoid Lobe lies below the line of the horizontal limb of the fissure of Sylvius and above the upper border of the zygoma, and a line representing the continuation of the latter backward to a point slightly above the superior curved line of the occipital bone. The posterior boundary of this ^ lobe corresponds approximately to a line drawn from the external portion of the 510 SURGICAL ANAT03IY. parieto-occipital fissure to the posterior limit of the base or root of the mastoid process. This lobe in front reaches as far as the posterior superior border of the malar bone. A line drawn parallel with and one inch, or two and one-half centi- meters, below the line of the horizontal limb of the fissure of Sylvius indicates the course of the superior temporo-sphenoid fissure. A line drawn parallel with and three-fourths of an inch, or two centimeters, below the latter line, indicates the course of the middle temporo-sphenoid fissure. The superior temporo-sphenoid convolution corresponds to the interval between the line of the horizontal limb of the fissure of Sylvius and the line of the superior temporo-sphenoid fissure. The middle temporo-sphenoid convolution corresponds to the interval between the lines of the superior and middle temporo-sphenoid fissures. Individual Variations and How to Determine Them. — It is to be borne in mind that the brain of one individual ditt'ers from that of another, and, therefore, there is no method which will in all instances represent the jiosition of the fissures and convolutions with absolute correctness. After the brain cortex is exposed in an operation, the Faradic current can be applied to decide what portion of the motor area of the cortex has been exposed. It can be readih' api^reciated that through so small an opening as that made l)y the trephine it is scarcely possible to recognize special fissures and convolutions, especially when we recollect how difficult it is at times to locate them in the dissection of the brain. Indications for Trephining. — Excluding trejihining for fracture of the skull, the cranial cavity is opened for one of several purposes — namely, to expose the superior and inferior maxillary nerves when it is puqiosed to excise one or both for trifacial neuralgia ; for the removal of the Gasserian ganglion, as described ; to remove a blood clot ; to control hemorrhage from one or both branches of the middle meningeal artery ; to open the lateral sinus in septic thrombosis consequent upon middle ear disease ; to remove part of the brain cortex, as in Jacksonian epilepsy ; to remove a brain tumor or a foreign body ; to evacuate an abscess ; to relieve intra-cranial pressure ; to tap tlie lateral ventricles ; for the relief of other- wi.se uncontrollable headache when the point of greatest pain can be located ; and for traumatic epilepsy. To Expose the Lateral Sinus. — In septic thrombosis of the lateral sinus con- sequent upon middle ear disea.se that portion of the sinus in relation witli the mastoid process, the sigmoid jiortion, is ex])osed. To reach this portion, first draw t\v(i lines, one vertical tlirougli the middle of the mastoid process, and a second on a level witli tlic roof of tlie I'.xlrrual auditory meatus and at a right angle to the first. At the ])oint of junction of these two lines apply the center pin of a one-inch trephine. The most superficial portion of this sinv;s is not so deeply situated as the ma.stoid antrum, being, as a rule, about one-fourth of an inch, or six milli- cramo-('i:rei;ral topogkaphy. 511 nipters, iVoni llio surface nC tin' bone. Befoi'c removing the clot f'nnii tlie sigmoid sinus the internal jugular \-cin sliould ln' ligated, to control hemorrhage and prevent dissemination of emboli. As a thrombus of the sigmoid sinus seldom occurs except as a complication of disease of the masstoid antrum, the latter is usualh' opened first, and then it is desirable to expose the sinus on its anterior aspect by removing the bony tissue .between tlie antrum and the sinus, which often contains the channels through which the sinus has become infected. Localized Affections. — In oiierating for focal epilepsy, brain tumor, or l)lood clot the trephine is applied to the skull directly over the part of the brain believed to be the site of involvement, as determined by localizing symptoms. The lines which indicate the courses of the fissures are the principal guides. Foreign Bodies. — In the removal — or perhaps it would be better to say the attempt at removal — of a foreign body, as these are mo.st commonly Indlets and in the majority of cases located with difficulty, the cranial cavity is attacked at the wound of entrance. The operation of trephining in this class of cases increases the chance of finding the foreign body and e.stablishes drainage. Temporo-sphenoid Abscess. — The most common forms of intra-cranial abscess are temporo-sphenoid, cerebellar, and extradural, whicli are usually the result of middle ear disea.se. In operating for temporo-sphenoid abscess, which is usually located in the posterior half of the lobe, first draw two parallel lines at right angles to Reid's base line, the anterior passing through the center of the external auditory meatus, and the other about one and one-fourth inches, or three centimeters, behind it. Apply the center pin of the trephine over a point one and one-fourth inches, or three centimeters, above Reid's base line and between the two vertical lines (Barker). Cerebellar Abscess. — In operating for cerebellar abscess, which is usually situateil in the front and outer part of the hemisphere of the cerebellum, apply the center pin of the trephine at a point one and one-half inches, or four centimeters, behind the center of the external auditory meatus, and one inch, or two and one- half centimeters, below Reid's base line (Barker). Extradural Abscess. — Tlie point over which to trephine in extradural or subdural abscess must depend, in a great degree, upon the presence of localizing symptoms. The constitutional evidences of pus and the history of the case, togetlier with circumscribed edema and localizing .symptoms, such as spastic con- traction or paresis of certain muscles, would constitute the most reliable guides. Septic meningitis, as far as the constitutional symptoms are concerned, frequently so clo.«ely simulates cerebral abscess that a differential diagnosis, in tlie absence of localizing symptoms, is impossible. To Tap the Lateral Ventricles apply the center pin of the tiephine one and 512 SURGICAL ANATOMY. one-quarter inches, or three centimeters, behind the center of the external auditory meatus and the same distance above Reid's base hne. The ventricle is reached by carrying a grooved director obliquely forward and upward toward a point two and one-half to three inches, or six to seven and one-half centimeters, above the ojipo- site external auditory meatus. The distance to which the grooved director must be inserted to reach the ventricle is from two to two and one-quarter inches, or five to five and one-half centimetei's (Keen). Headache and Traumatic Epilepsy. — In otherwise uncontrollable headache, when the point of greatest pain can be located, the trephine is applied at that point. In traumatic epilepsy the trephine is ajiplied to the site of the original injury. Craniectomy, or removal of a .section of the calvaria to allow expansion of the brain in cases of idiocy, is, in the author's opinion, inadvisable, and might be compared to removal of a section of a nutshell to allow increased growth of a nut, the kernel of which is dead. THE INTERIOR OF THE CEREBRUM. Material. — In order to study the brain to the best advantage the dis.sector, as previously remarked, should have at least two preserved brains at his disposal. One brain may be u.sed for the study of the fissures, convolutions, and interior of the brain ; and the other f(.>r making sections of the l)rain. Dissection. — Having completed the study of the fissures and the convolu- tions, next examine the interior of the cerebrum. Place the brain on its base, and sei^arate the hemispheres of the cerebrum, to widen the longitudinal fissure, thus exposing the bottom of the fissure. This is formed in great jJart by a mass of Avhite matter, — the corpus callosum, or the great transverse commissure of the cerebrum, — while in front of and behind the corpus callosum the fissure extends without interruption to the base of the brain. Make a horizontal section of one or both hemispheres on a level with the floor of the longitudinal fissure. AVhen both hemispheres are sliced away to the level of the fioor of the longitudinal fissure, the upper surface of the corpus callosum is well exposed. The corpus callosum can now be studied from two points of view : from al)Ove in tbe present dissection, and from tlie siile l)y looking at its sagittal section, seen in the preparation previously made liy .severing the two halves of the lirain in the line of the longitudinal fissure. The Corpus Callosum, tlie great transverse commissure of the cerebrum, is a tran.sverse band of white matter which s|)ans the longitudinal fissure and connects the hemispheres of the cerebrum for ne;u-ly half their length. The ful.c cerebri PLATE CXXV. Anterior cerebral a. White matter Grey matter Median raphe' Strioe longltudinales S— II- 3;>, CORPUS CALLOSUW AND HORIZONTAL SECTION OF CEREBRUM, 513 PLATE CXXVI, Body of corpus callosum Velum interpositum Fornix Paracentral sulcus Foramen of Monro Gyrus fornicatus Lateral ventricle Callosal fissura Calloso-marginal fissure Marginal convolution Paracentral loLule Peduncle of pineal l:)ody Fissure of Rolando Pineal body Pia mater entering third ventricle Splenium of corpus callosum Subparietal sulcus Tela choroidea inferior Quadrate lobe or precuneus Calcarine fissure Parieto-occipital fissure Cuneus Genu of corpus callosum Septum lucidum (cut) Fifth ventricle Anterior commissure' Optic n'. Optic commissure Lamina cinerea Anterior pillar of fornix Pituitary body Third Ventricle Optic thalamus Tuber cmereum Cerebellum Arbor vitae Medulla oblongata Fourth ventricle Superior medullary velum Corpora quadragemina Pons Varolii Aqueduct of Sylvius Posterior commissure Crus cerebri Corpus albicans Middle commissure INTERNAL SURFACE OF CEREBRUM SECTION OF VENTRICLES OF BRAIN, 510 THE INTERIOR OF THE CEREBRUM. 617 touches the posterior portion of tiie eorpu.s caliosuni ; the greater part of the body of the corjius callosuin and its anterior extremity are separated for a considerable distance from tiie ialx cerebri. Tlie corpus callosum is sHghtly convex from before backward on the upper surface, is between three and four inciies, or seven to ten centimeters, in length, and extends nearer to the anterior tlian to tlie posterior end of the cerebrum. It is wider beliind, wiiere it measures about one inch, or two and one-half centimeters, and is thicker at each end, especiallj' at the posterior extremity, than in the middle. It forms the roof of the lateral ventricles, which are cavities located within the hemispheres of the cerebrum. On its dorsal surface, extending along its middle line, a liut-ar depression exists, the raphe. On each side of the rai)lie, and running parallel with it, are two slightly elevated longitudinal bands, tlie striae longitudinales, y the scjituni luciiluni, wiiicli separates it from the corresponding cornu of the opposite ventricle; m front, by the genu of the corpus callosum ; and externally, liy the caudate nucleus. Its _^oor is formed in great part by the caudate nucleus, which projects into it, and to a slight extent In' the I'ostrum of the corpus callosum. The posterior cornu of the lateral ventricle, tin- smallest of the three cornua, commences in the body of the ventricle ojiposite the splenium of the corpus callo sum, and at the same point as the middle cornu. It extends horizontally back- ward, outward, and then inward into the occipital lobe. Its roof is formed by tlio.se fibers of the sjjlenium of the corpus callosum (forceps major) which pass back- ward and outward and become continuous with the white matter of the occipital lobe. On its inner wall is seen the hi[)pocampus minor, or calcar avis, produced by the calcarine fissure ; above this is a smaller prominence, the bull) of the cornu, produced by the bulging of the fibers of the forceps major into the cavity, above and internal to the hippocampus minor. On the floor is seen a slight elevation, produced by the fasciculus longitudinalis inferior, which passes from the occipital to the temporal lobe. At the point where the middle and posterior cornua meet a triangular, smooth surface is seen, called by Schwalbe the trigonum ventriculi. The middle or descending cornu of the lateral ventricle, tlie longest of the three cornua, may be considered tlie continuation of the cavity of the ventricle into the temporal lobe ; it commences ojiposite the splenium of the corpus callosum, in the body of the ventricle, at the same point at which the posterior cornu begins. It extends backward and outward around the posterior extremity of the optic thala- mus, and then runs downward, forward, and inward to reach the base of the brain, terminating about an inch, or 2.5 centimeters, from the tip of the temjioro-sphenoid lobe. Its roof is formed by those fibers of the body of the corjius callosum (tape- tum) which pass outward and become continuous with the white matter of the temporo-sphenoid lobe, and by the tail of the caudate nucleus, the ta'uia semi- circularis, and the amygdaloid tubercle. T\iv floor is foiincil in great part by the eminentia collateralis. Upon the inner ivall are seen the following structures, named from without inward : the hippocampus major, and pes hippocampi, the corpus fimliriatum, the choroid plexus, and the fascia dentata or dentate convolution. 522 SURGICAL ANATOMY. Dissection. — Next make a transverse section of the remaining portion of the body of tlie corpus callosum at about its middle, and dissect one half forward and the other half backward. If carefully executed, this dissection exposes the fornix and the septum lucidum. The Fornix, the longitudinal commissure of the cerebrum, is a triangular mass of white matter situated beneath the corpus callosum, and is continuous posteriorly with the splenium of the corpus callosum. It overlies the velum interpositum, which separates it from the third ventricle and the optic thal- amus. It consists of a main portion, or body, and an anterior and a i^osterior crura. The body of the fornix is triangular in shape, the apex of the triangle being directed anteriorly. The fornix is adherent behind to the splenium of the corpus callosum, and is attached above and in front to the septum lucidum, and above and behind to the corpus callosum ; below, it rests upon the velum interpos- itum, and lies above the third ventricle. The sides of the body of the fornix pro- ject into the lateral ventricles, overlapping the inner portion of the optic thalami and choroid plexuses. The fibers of the under surface of the fornix behind are so arranged as to give rise to the designation the lyre, which has been bestowed upon them. The anterior crura, or pillars of the fornix, are two cylindric bundles of nerve-fibers which are given off from the anterior extremity or apex of the body of the fornix, whence they diverge' and descend in front of the optic thalami and the foramina of Monro and then through the gray matter in the sides of the third ven- tricle, to the base of the brain, where thej^ form the white matter of the corpora albicantia, or mammillary eminences. Fibers pass from the corpora albicantia to the optic thalami ; these fibers constitute the bundles of Vicq d'Azyr, and are probably not directly continuous with the fibers of the fornix. In their descent the anterior pillars are joined by the tsenise semicirculares and hy fibers from the septum lucidum and peduncles of the pineal gland. Between the anterior crura and the anterior extremities of the optic thalami are the oval openings of com- numication between the lateral ventricles and the third ventricle, the foramina of Monro. Tlie posterior crura, or pillars of the fornix, arise posteriorly from each side of the body of the fiiniix, whence they diverge and descend into tlic middle cornua of tlie lateral ventricles. Here each cms lies within the concavity of the curve described by the hippocampus major as fiir as tlie pes hippocampi. The lateral liordcrs of the ]iost(>rior crura of the fornix are known as the corpora fimbriata, (ir taeniae hippocampi. Tlie septum lucidum is a triangular vertical partition situated between the PLATE CXXVIII. Tenia semicircularis Optic thalamus Pia mater entering at hippocampal fissure ^^choroid plexus removed) Pes hippocamp Genu of corpus callosum Fifth ventricle Septum lucidum Corpus striatum Hippocampus major Eminentia collateralis' Hippocampus minor Bulb of posterior cornu of lateral ventricle Choroid plexus Fornix Splenium of corpus callosum Posterior pillar of fornix FORNIX AND LATERAL VENTRICLES, AND DESCENDI^ 523 U OF LEFT LATERAL VENTRICLE. THE IXTKIUOR OF THE 'RKBKUM. 525 anterior portion of the bodies of tlie two lateral ventricK's and between the anterior eornua of those ventricles. The base of the triangle is directed downward and forward, and the apex backward, into the narrow interval between the anterior part of the body of the fornix below, and the corpus callosum above. The septum lufiilum is attached above to the under surface of the body of the corpus callosum ; in front, to the concavity of the genu ol' tlie corpus callosum ; and below, to the rostrum of the corpus callosum and to the body and anterior crura of the fornix. It is composed of two lamina?, between which is the cleft-liko interval known a the fifth ventricle. The fifth or Sylvian ventricle is not provided with an outlet, but is a com- pletely inclosed space. Each of the lamin;e of the septum lucidum, which bound this ventricle laterally, consists of an inner gray layer, a middle white layer, and an outer layer of ependyma which is part of the ependyma that lines the lateral ventricles. The fifth ventricle differs from tlie other ventricles in its mode of development ; it is a portion of the great longitudinal fissure which has become inclosed by the formation of the corpus callosum and fornix. Dissection. — With a pair of scissors slice away a horizontal section from the superior portion of the septum lucidum, when, with a little care, the laminte can be pushed apart and the fifth ventricle opened. Should the ventricle contain more than the usual quantity of fluid, it can lie more readily seen tlian if it were in a normal state. Before reflecting the fornix examine the structures seen within the lateral ventricle, commencing with the corpora striata, wliicli project into the anterior eornua. Corpus Striatum. — The corpora striata (anterior cerebral ganglia) are the anterior [lair of basal ganglia. The })ortion seen within the anterior cornu of the lateral ventricle is the intra-ventricular portion, or caudate nucleus. It is so called in contradistinction to the larger extra-ventricular portion, or lenticular nucleus, which occupies the white substance of tlie hemisphere of the cerebrum. To expose both the lenticular nucleus and the caudate nucleus in one dissection it is necessary to make horizontal sections of the hemisphere ; these sections will be described further on. The Caudate Nucleus is a pear-shaped mass of gray matter having its broad extremity, or head, directed forward into the forepart of the body and the anterior cornu of the lateral ventricle, and its narrow extremity, or tail, directed outward and backward. It lies to the outer side of the optic thalamus, and is prolonged into the roof of the middle horn of the lateral ventricle as far as its anterior ex- tremity, where it terminates in the amygdaloid tubercle. Crossing the surface of the caudate nucleus are numerous small veins emptying into the vein of the 526 SURGICAL ANATOMY. corpus striatum, which Ues in the groove between the caudate nucleus and tlie optic thalamus. The Taenia Semicircularis, or Stria Terminalis, is a very narrow longitudinal band of white fibers, which lies in the groove between the caudate nucleus and the optic thalamus, and conceals from view the vein of the corpus striatum. It extends from the anterior crus of the fornix, with which it is continuous in front, back- ward through the floor of the body of the ventricle, and into and along the roof of the middle cornu as far as the amygdaloid tubercle, where it ends. Where the surface of the anterior portion of the taenia semicircularis is more transparent and less dense than elsewhere was called ])y Tarinus the "Imrny l)and." The Optic Thalami (posterior cerebral ganglia), the posterior pair of basal ganglia, can not be seen to advantage at this .stage of the dissection, without dis- arranging the parts overlying them and until the fornix and the velum interposi- tum have been removed ; their description, therefore, will be deferred. It is suffi- cient to say here that the optic thalamus is an oblong mass of white and gray matter Ij'ing to the inner side of the caudate nucleus and the taenia semicircularis, part of the upper surface of which is hidden by the choroid plexus, the corpus fimbriatum, and the lateral portion of the body of the fornix. The Choroid Plexus is a red, convoluted, vascular fringe, formed in the free margin of the velum interpositum, extending from the foramen of Monro back- ward over the optic thalamus into the descending cornu of the lateral ventricle, where it lies on the hippocampus major and extends to the end of tliis cornu of the ventricle. It is covered throughout by the ventricular epithelium, or epen- dyma, which passes from the corpus fimbriatum to the taenia semicircularis and optic thalamus ; the ependyma thus separates the plexus from the cavity of the ventricle. Behind and between the foramina of Monro the choroid plexus of one lateral ventricle becomes continuous with that of the other, and from the point of junction the choroid plexuses of the ventricle extend backward. The Corpus Fimbriatum, Taenia Hippocampi, or Fimbria, a narrow band of white matter, is the edge of the posterior crus of the fornix, which rests upon the posterior end of the optic thalamus, the choroid plexus intervening, and is con- tinued into the descending cornu of the lateral ventricle. Here it rests between the concave margin of tiie hij)pocami)Us major and the pia mater, whicli passes through the hippocampal fissure. It extends as far as the uncus of the hippo- campal gyrus. TI:u Hippocampus Major, or Cornu Ammonis, is the prominent convex, white cniincucc wliich forms p;irt choroid plexus of the descending cornu of the lateral ventricle, thus breaking through the epithelial lining of the ventricle ; displace the choroid plexus inward, and slightly depress the corpus fimbriatum and hippocampus major. Tliis {irocedure exposes the fascia dentata, and separates the margins of the hippocampal fissure. The Fascia Dentata, or Dentate Convolution, a serrated band of gray matter, is the margin of the hippocampal convolution in relation with the hippocampal fissure. The serrations or indentations of the fascia dentata are produced by the vessels of the pia mater, which projects through the hippocampal fissure into the descending cornu of the lateral ventricle. The fascia dentata extends from near the splenimu of the corpus callosum to the anterior extremity of the descending cornu of the lateral ventricle. As the epithelial lining of the ventricle must be divided in order to expose the fascia dentata, that convolution is external to the wall of the ventricular cavity. The Hippocampus Minor, Calcar Avis, or Ergot, is a small, convex, white eminence which occupies tlie floor and inner wall of tlie posterior cornu of the lateral ventricle. It is produced by the calcarine fissure, and is at times but faintly marked. The Eminentia Collateralis, or Pes Accessorius, may be recognized at its commencement as a smooth white eminence fitting into the angle of divergence of the hippocampus major and hippocampus minor, at the junction of the middle and posterior cornua of the lateral ventricle. It extends forward as the floor of the middle cornu of the lateral ventricle almost to the extremitj^ of this cornu. It is produced by the collateral fissure. Dissection. — Next divide the fornix transversely at about its middle, and reflect the one half forward and the other backward, thus exposing the greater part of that process of pia mater — the velum interpositum — which lies above the epithelial roof of the tliird ventricle. To expose thoroughly the velum inter- po.situm, especially that part of it which occupies the central portion of the trans- verse fissure, make a longitudinal incision through the jwsterior part of the fornix and corpus callosum ; then reflect (liese fla])s laterally. The Velum Interpositum, or Tela Choroidea Superior, is that process of the pia mater which reaches the interior of the brain by way of the horizontal portion of the transverse fissure, passing 1)etween the splenium of the corpus callo.sum and the corpora quadrigemina. It is a double layer of pia mater, and is triangular in 532 SURGICAL ANATOMY. shape, like the fornix ; it lies beneath tlie fornix and the corpus callosvuii. It covers the quadrigeminal bodies, the pineal body, the third ventricle, and part of the optic thalami. Its borders contain the choroid plexuses of the lateral ven- tricles, while in its under surface are situated the two choroid plexuses of the third ventricle. The latter plexuses are continuous with the choroid plexuses of the lateral ventricles just behind the foramina of Monro. Running one on each side of the median line of the velum interpo.situm, between its two layers, are the two veins of Galen, formed by the union of the veins of the corpora striata and the choroid veins, in addition to small twigs from surrounding structures. They unite posteriorly to form a single trunk, which joins the inferior longitudinal sinus to form the straight sinus at the junction of the inferior margin of the falx cerebri with the anterior margin of the tentorium cerebelli. Dissection. — Raise the velum interpositum and the choroid plexuses and turn them backward. Especial care is necessary in raising the posterior part of the velum interpositum so as not to rai.se the pineal gland with it, as the gland is closely invested by the lower layer of jjia mater entering the velum. This dissec- tion exposes the third ventricle, the three commissures of that ventricle, the anterior crura of the fornix, the optic thalami, the pineal body and its peduncles, and the quadrigeminal body. In making the dissection it frequently happens that the middle commissure of the third ventricle is broken, and the dissector, if not familiar with this fact, might conclude that it was absent in the brain under exam- ination. Fissure of Bichat. — Before describing the parts exposed by the removal of the velum interpositum, the great transver.se fissure of the brain, or fissure of Bichat, which is now opened up throughout, should be carefully observed. To do this to the best advantage it is necessary to remove the velum interpositum and the choroid plexuses of the lateral and third ventricles with the adherent epi- thelium. The central horizontal or transver.se portion of this fissure, through which the velum interpositum passes, is the continuation of the interspace between the cerebrum and the cerebellum seen in the undissected brain with the pia mater removed. This central portion is contimious with the lateral portions, or hippo- campal fissures, which are seen in the dissection of the middle cornua of the lateral ventricles, thus making the fissure, as a whole, horseshoe shaped. The Third Ventricle is a narrow, oblong cavity situated in the middle line of the cerebrum, lietwecn the optic thalami and the peduncles of the pineal liody, and reaching to the base of tlio brain. It is wider and shallower ln-liiiul tlian in front. It is Itoundcd alioir by tiic velum interpositum, iiltlidu^li its immediate roof is formed by a thin epithelial layer which is contimious with llic lining epithelium or ependyma of the ventricle; on the sides, by the optic tiialami and the peduncles PLATE CXXXI, Choroid plexus Anterior pillars of fornix(cut) Veins of Galen Descending cornu of left lateral ventricle Velum interpositum Body of fornixfreflected) Lyra VELUM INTERPOSITUM AND CHOROID PLEXUS. PLATE CXXXII. Portion of corpus callosum Anterior commissure. Middle commissure. Peduncle of pineal body Posterior commissure, \ \ \ ^S^^ I Pineal body, Choi-oid plexus ,Septum lucidum rAnterior pillar of fornix Head of caudate nucleus Third ventricle ,Optic tinalamus Tenia scmicircularis Corpora quadrigemina Superior cerbellar pedu Superior medullary velu Eminentia teres Floor of fourtli ventricle Trigonum hypogloss Ala cinerea' Tuberculum acusticum _, Restiform body Hippocampus major Posterior pillar of fornix Cerebellum Hippocampal fissure Fascia dentata Lateral column of medulla oblongata Funiculus cuneatus of medulla Funiculus gracilis of medulla VENTRICLES AND NUCLEI OF THE BRAIN. THE IMT.Uloi; OF TIIK CEREBRrM. 637 of the pineal body ; in ;'/«/(/, liy Ihi' anterior commissure and the anterior ]iillars of the fornix ; and behind, by the posterior eonnnissure, tlie orifice of the atjueduet of iSylvius, and the pia mater, passing from tlie upper surface of the pineal body to the inferior layer of the velum interpositum. Its floor is formed by the bodies wliirh till the interpeduncular space of tiie base of the brain and tiie su]ierior sur- face of the crura cereliri at their origin from the pons Varolii. The structures in the inter|n'duncular Space are named, from before backward, tlie lamina cinei'ea, tiie tuber cinereum, the infundibuium, tlie cor])ora albicantia, and the jKistcrior perforated space. Commissures. — Stretching across tiie ventricle are the anterior, middle, and posterior commissures. The anfcrior commissure is situated in front of the ante- rior crura of the fornix. It is comjiosed of white matter and connects the two temporal lobes of the cerebrum. The iniddle commissure is composed almost entirely of gray matter, is the largest, and is about one-half an inch, or twelve millimeters, in width. It connects the optic thalami, and, as has been observed, is frequentl}' torn across in the dissection of the brain. The jwsterior commissure, the smallest of the three, is situated in front of and beneath the pineal liody, and above the anterior opening of the aipieduct of Sylvius. It is composed of white matter, connects the optic thalami, and probably contains decussating fibers derived from various sources. The Foramina of Monro are the orifices of communication l)etween the lateral ventricles and the third ventricle. Each foramen is liounded in front by the corresponding anterior cms of the fornix, behind by the optic thalamus and choroid jilexus, above by the anterior eras of the fornix, and below by the epen- dyma reflected from the optic thalamus to the anterior cms of the fornix. The two foramina have a common orifice in the third ventricle, thus forming a Y-shaped passage, called the foramen commune anterius, through which cerebro-spinal fluid in one lateral ventricle may enter tlie other lateral ventricle. Aqueduct of Sylvius. — At the posterior extremity of the third ventricle, and beneath the posterior commissure, is .seen the anterior orifice of the aqueduct of Sylvius, or iter e tertio ad quartum ventriculum. This is a narrow passageway about three-fourths of an inch, or two centimeters, in length, and passes beneath the quadrigeminal body to establish a communication between the third and fourth ventricles. It is lined with ependyma which is continuous with, and similar to, that lining the ventricles which it connects. Its roof is formed by the lamina quadrigemina, a plate of gray matter whicii supports the corpora quadrigemina. Its floor is formed by the tegmental portions of the crura cerebri. The gray matter in its floor contains the nuclei which give origin to the third and fourth cranial nerves. 538 SURGICAL ANATOMY. The Optic Thalami, tlie posterior j)air of cerebral ganglia, are two oval masses of white and gray matter. They are convex from before backward, and slightly so from side to side, and have their long axis directed obliquely from before backward and from within outward. They lie one upon each side of the third ventricle, between the tails of the caudate nuclei, and rest upon the crura cerebri. Each optic thalamus forms a large portion of the floor of the body of the lateral ven- tricle, while its posterior end projects into the descending cornu of that ventricle. Each optic thalamus consists of two extremities : an anterior, called the anterior tubercle, which forms the posterior boundary of the foramen of Monro, and a posterior, called the pulvinar, nr posterior tubercle. The upper surface of each is partly free and partly covered by the choroid plexus of the lateral ventricle, the velum interpositum, and the lateral border of the body of the fornix. On its upper surface is situated an antero-posterior groove, called the sulcus choroideus, for the attachment of the velum interpositum. In the groove between the caudate nucleus and the optic thalamus lies the tasnia semicircularis. The optic thalami are connected by the middle and posterior commissures of the third ventricle. Running along the upper border of each optic thalamus from behind forward are the ]H'duncles of the pineal gland. Geniculate Bodies. — Tlie under surface of the posterior extremity of each optic thalamus, which forms part of the roof of the middle cornu of the lateral ventricle, presents two small gray eminences, the internal and external geniculate bodies. To see these bodies satisfactorily, turn the brain on its side and rai.se the po.sterior extremity of the optic thalamus. The internal geniculate bodies are connected internally with the nates of the corpora quadrigemina through the medium of the brachia, and externally are directly continuous with the optic tract. The Pineal Gland or Body, Conarium, or Epiphysis Cerebri, is a small, red- dish gray, oval body, about one-fourth of an inch, or six millimeters, in length. It is directed forward and upward, and rests upon the groove between the ante- rior pair of the corpora quadrigemina and above the posterior commissure of the third ventricle. From the base of the pineal body a white cms, or peduncle, pas.ses forward u]ion each side of the tliird ventricle and along the upper and inner surface of tiie ojitic thalami to the anterior crura of the fornix, with which the peduncles become contiimous. Posteriorly they are joined together in front of the base of the pineal body, and are connected with the posterioi' commissure of the third ventricle. Tlio Corpora Quadrigemina, or Optic Lobes, are .situated immediately behind llie tliird ventricle, and are composed of four eminences. These are arranged in two pairs: an iinteriiir or nppi'r, the larger of the two, and called the nates, and a PLATE GXXXIIl, Corpus albicans Optic tract Infundibulum Root of Olfactory tract Optic commissure Pituitary body. Superior peduncle of cerebellu Auditory n. Pars intermedia of Wrisberg(n.) Inferior peduncle of cerebellum Abducent n Glossopharyngeal n Olivary body Spinal accessory n. Anterior pyramidal tract of medulla oblongata Medulla oblongata Crus cerebri External geniculate body nternal geniculate body Pulvinar of optic thalamus Corpora quadrigemina Pathetic n. Trifacial n. Pons Varolii - Middle peduncle : cerebellum y Facial n. Restiform body Pneumogastric n. Hypoglossal n Anterior root of first cervical n Posterior root of first cervical n. LATERAL VIEW OF CORPORA QUADRIGEMINA, PONS, AND MEDULLA, 539 PLATE CXXXIV. Septum lucidum Anterior pillars of fornix ■ Peduncle of pineal body Pineal body Third ventricle Caudate nucleus / Optic thalamus \^ u ' I /Tenia semicircularis Superior peduncle of cerebellum Superior medullary velum Middle peduncle of cerebellum -^ Inferior peduncle of ^ cerebelluii gitudinal median sulcus Emmentia teres Tuberculum acusticu Trigonum hypoglossi Ala cinerea Posterior median fissure of medulla oblongata Funiculus gracilis Conductor sonorus StriiE medullares Lateral tract Funiculus cuneatus THIRD AND FOURTH VENTRICLES AND CORPORA QUAORICEMINA, 642 THE IXTERIOR OF THE CEREBRUM. 5-l."> postcrinr or lower, called tin- testes. They are situated uikui a layer of gray matter known as the lamina quadrigemina, whieh overlies tlie aqueduct of Sylvius. They give off anteriorly four liands or hraehia, which arc composed ol' white matter externally and gray matter internally. The brachia of the nates, or supe- rior brachia, pass under the internal geniculate bodies into the optic tracts. The hraehia of the testes, or inferioi- bi-achia, pass below and external to the brachia of the nates, and below tlu' internal geniculate bodies leave the surface. The posterior (luadrigcniinal bodies or testes ai'e cacli connected with the lieuusphere of the ceri;- bellum by a broad band of white matter, the superior peduncle of the ceivbcllum [l>niirxsus e cerebello ad testes). Dissection. — In order to see the superior cerebellar peduncles more clearly, the anterior extremity of the middle lobe of the cerebellum should be lifted sliglitly and |)ushed backward, or, better, a longitudinal incision should be carried through the middle of this lobe, and each half displaced laterally. This will expose these peduncles clearly and also show the fillet and the valve of Yieussens. The Superior Peduncle of the Cerebellum (processus e cerebello ad testes) con- nects the hemisjjhere of the cerebellum with the opposite hemisphere of the cere- brum. It passes upward, forward, and inward along the side of the anterior part of the fourth ventricle, and beneath the corpora cjuadrigemina, where the fibers of the two peduncles decussate ; beyond the corpora quadrigemina, along with the teg- mental fibers of the crura cerebri, the fibers of each peduncle are continued to the optic thalamus and lenticular nucleus of the opposite hemisphere of the cerebrum. The Valve of Vieussens, the anterior or .superior medullary velum, is a tri- angular layer of white matter, narrow in front and broad behind, stretched between the superior peduncles of the cerebellum, and extending from the anterior extremity or nodule of the inferior vermiform process of the cerebellum to the corpora quadri- gemina. It forms a portion of the roof of the fourth ventricle. Along the middle line of the upper surface is a longitudinal ridge, the frenulum. The lower half is overlapped by the lingula, a corrugated lobule of gray matter jirolonged from the anterior extremity of the sujierior vermiform process. The trochlear nerves decus- sate witlnn it, and emerge from its dorsal surface, just behind the inferior <}uadri- geminal bodies. The fillet is a small, flat band or bundle of nerve fibers situated below and external to tlie superior peduncle of the cerebellum. It emerges from the pons at the upper limit of its posterior region, and appears as a triangular band which is situated above the crus cerebri and disappears under the testis and brachium of the testis. Dissection'. — If the superior and inferior vermiform processes of the cere- bellum were not divided longitudinally when exposing the valve of "\"icussens, 544 SURGICAL ANATOMY. they should be divided now, and each lialf reflected laterally to expose the fourth ventricle. The Fourth Ventricle is a quadrangular, lozenge-shaped space, situated between the cerebellum and the posterior surface of the medulla oblongata and pons Varolii. The roof is formed anteriorly by the valve of Vieussens and the superior peduncles of the cerebellum, and posteriorly by the inferior medullary velum, the inferior vermiform process of the cerebellum, the choroid plexus, and the tela choroidea inferior. The floor is formed by the posterior surface of the medulla oblongata and pons Varolii. It is bounded laterally by the superior peduncles of the cerebellum above, and the inferior peduncles of the cerebellum below. The ventricle is lined by the ependyma or epithelial wall of the ventricles of the brain. The ventricle presents four angles, a superior, an inferior, and two lateral (also called the lateral recesses of the ventricle). The widest part of the ventricle corresponds to the interval between the lateral angles, which are at about its middle. The Tela Choroidea Inferior is that part of the pia mater on the posterior surface of the medulla oblongata which completes the posterior part of the roof of the fourth ventricle. It contains three perforations : the foramina of Magendie, Key, and Retzius. The foramen of Magendie is located in the median line near the inferior angle of the fourth ventricle. The foramina of Key and Retzius are located at the lateral recesses of the ventricle. By way of these openings the ventricle communi- cates with the general subarachnoid space. The two choroid plexuses of the fourth ventricle are also derived from the pia mater by the intrusion of its folded edge into the roof of that cavity. They extend forward from the posterior angle of the fourth ventricle near the median line for a short distance, and then diverge to reach the lateral recesses of the ven- trick'. The fourth ventricle communicates with the third ventricle by way of the aqueduct of Sylvius, and with the central canal of the spinal cord through an opening in the inferior angle which is dilated and is called the ventricle of Arantlus. The flof)r of tlic fourth vuntrick; is its most important part, for the reason that tlie nuclei of most f)l'tlu' cranial nerves are situated there. It is composed chiefly of gray matter continuous willi the gray matter of the spinal cord. Occupying the middle line of the fliKir of the fourth ventricle is the median longitudinal fissure. It extends from the posterior orittceof the aqueduct of Sylvius to the pos- terior or inferior angle of the ventricle, which is at the point of divergence of the II— :i5 PLATE CXXXV. Head of caudate nucleus Anterior limb of internal capsule Posterior limb of internal capsule Lenticular nucleus External capsule Claustrum Island of Reil Rostrum of corpus callosum Septum lucidunn ,Optic thalamus Anterior cornu of right lateral ventricle Anterior pillar of fornix Tenia semicircularis Tail of caudate nucleus Choroid plexus' Posterior pillar of fornix' Hippocampus major' Pia mater in hippocampal fissure Posterior cornu of right lateral ventricio Velum interpositum Body of fornix Spleniuni of corpus callosum TRANSVERSE SECTION OF CEREBRUM. 54G THE INTERIOR OF THE CEREBRUM. 547 restiibnn Ijodics (if the inedulla. This fissure is coiitinudus helow with tiie central canal of the spinal cunl. This portion of the fourth ventricle has received the name of calamus scriptorius because of the resemhlance of the longitudinal fis- sure and the diverging posterior pyramids and restiform bodies to the point of a pen. Immediately to each side of the median furrow is a longitudinal ridge, the eminentia teres. Crossing this eminence in the lower half of the ventricle are bands of white matter, the auditory strite or striae acusticae. To the outer side of the eminentia teres and anterinr to tlie auditory striie is a depressed area, the svpe- rior fovea, while behind the auditory stria^ and to the outer side of the eminentia teres, are two furrows so united as to form an invci'ted V, the iitfcrior fovea; the floor of the inferior fovea is known as the ala cinerea. The trigonum hypoglossi is the area of the floor of the fourth ventricle bounded bj^ the longitudinal fissure, stria3 acusticfe, and inferior fovea, and covers the nucleus of the hyi^glossal nerve. The tuberculum acusticum is the triangular area situated between the inferior fovea and the clava of the funiculus gracilis, and extending forward under the striise acustica;. In front of the superior fovea and external to the eminentia teres is a small eminence of dark gray matter, the locus caeruleus. Prolonged forward from the locus caeruleus, at the side of the eminentia teres and extending to the upper end of the floor of the ventricle, is a thin streak of dark gray matter, the taenia violacea. The locus cseruleus and taenia violacea are produced by the substantia ferruginea, whose dark color is seen through the overlying white matter. The substantia ferruginea is the dark, pigmented mass seen in sections of the upper part of the floor of the fourth ventricle. The ependyma lining the fourth ventricle is contin- uous through the acjueduct of Sylvius with that lining the third ventricle. Dissection. — Next complete the dissection of the cerebrum by making hori- zontal sections of the corpora striata and optic thalami, carrying the incisions through to the external or lateral surface of the hemisphere. This will expose the caudate nucleus, the internal capsule, the lenticular nucleus, the external capsule, the claustrum, and the island of Reil from within outward in the order named. The Caudate Nucleus, or intra-ventricular jjortion of the corpus striatum, is the more anterior of the gray basal ganglia, and has been described. The Internal Capsule lies external to and behind the caudate nucleus, and separates the caudate from the lenticular nucleus, and the lenticular nucleus from the optic thalamus. The internal capsule, composed of white matter and some- what crescentic or angular in shape, consists of a genu and two limbs, an anterior and a posterior. The anterior limb, named by Spitzka the caudo-lenticular portion, intervenes between the caudate and lenticular nuclei. The poaterior limb, named by the same author the thalamo-lenticular portion, intervenes between the 648 SURGICAL ANATOMY. optic thalamus and the lenticular nucleus. The g(;nu, the point where the capsule presents the greatest angularitj', is opposite the interval between the caudate nucleus and the optic thalamus. Through the internal capsule the nerve fibers pass in their course from the gray matter of the cortex of the cerebrum and caudate and lenticular nuclei to the crus cerebri, which transmits these fibers from the cerel>rum to the pons, medulla oblongata, and spinal cord. In addition to these fibers the internal cap- sule contains fibers from the cerebral cortex to the optic thalamus. The anterior third of the internal capsule contains the fibers from the cortex of the prefrontal lobe, or silent region, the middle third, the filjcrs from the motor or Rolandic area of the cortex of the cerebrum, and the posterior third, the sensory fibers from the occipital and temporal lobes. Destruction of the anterior two-thirds of the posterior segment of the internal capsule, which occurs in many cases of apoplexy, results in motor paralj'sis of the opposite side of the body. This paralj'sis is diffuse, and not confined to a group of muscles, as in lesions of the cerebral cortex, while destruction of the poste- rior ])art of the posterior limb of the internal capsule results in loss of sensation of the opposite side of the body. A small hemorrhage in the capsule will cause paralysis of that part of the opposite side of the body supplied by the fibers compressed by the clot of l„)lood. The Lenticular Nucleus, or exti'aventricular portion of the corpus striatum, is larger than the caudate nucleus, is oval in form, and lies behind and to the outer side of the caudate nucleus. It is separated from the caudate nucleus by the anterior limb and genu of the internal capsule, and from the optic thalamu-s hy the posterior limb of the internal capsule. The external capsule is a band of white matter which lies to the outer side of the lenticular nucleus, and joins the internal cap.sule below the lenticular nucleus. The claustrum is a thin la3'er of gra}' matter, laying to the outer side of the external capsule. The Island of Reil, previously described, is external to the claustrum, and separated from it l)y a layer of white matter. White Matter of Cerebrum. — In the dissection of the cerebrum, which will be completed when the crura cerebri have been traced from the upper border of the jions to each hemisphere, it should lie notod that the white matter of the cere- brum is compiiscil of three systems or sets of medullated nerve fibers, the ascending or peduncular, the transverse commissural, and the longitudinal com- missural. The ascenilliirj or peduncular fibers are those fibers of the crura cerebri M'hiili, ill diverging to reach the nerve cells of the cerebral cortex, form the corona THE rO.\S VAROLII. 549 radinta, so called on account of the crown-like radiation of its fibers. The trans- verse commissural fibers include the fibers of tlic corpus callosum and the anterior and posterior commissures of the third ventricle. The longitudinal commissural fibers include the fibers of the fornix, tlie strife longitudinales of the corpus callosum, tlie tienia >>emicircu]aris, tihers in the gyrus fornicatvis and gyrus hippo- campi, and tlie peduncles of the iiineal body. They also include the associating fibers: tliose fibers which connect the cells of neighboring and of more distant con- volutions. THE PONS VAROLII. DissECTiox. — Having completed tlie dissection of the cerebrum, excepting the tracing of the crura cerebri, turn the l)rain so as to expose the base, and .study the pons, then the medulla oblongata, and lastly the cerebellum. The Pons Varolii, or Tuber Annulare, is that division of the brain through the medium of wliicli tlie other three divisions of the brain are united. It is con- nected with the cerebrum, above, by the crura cerebri, or peduncles of the cere- brum ; with the cerebellum, behind, by the middle peduncles of the cerebellum ; and with the medulla, below, by tlie fibers of the jayramidal tract of tlie medulla oblongata. It is situated behind the crura cerebri, in front of thq medulla oblon- gata, between and below the hemispheres of the cerebellum, and between the posterior portion of the temporo-sphcnoid lobes of the cerebrum. In the cranial cavity it lies below the level of the superior occipital foramen of the tentorium cerebelli, and rests upon the basilar process of the occipital bone and the posterior surface of the body of the sphenoid bone. It is quadrangular in shape, and is composed chiefly of white matter, the fillers of which are arranged transversely and longitudinally. It presents two surfiaces, an anterior and a posterior. The anterior surface is markedly convex from side to side, and slightly so from before backward, and measures transversely altout one and one-half inches, or four centi- meters, and is about one inch, or twenty-five millimeters, in length. The anterior surface is marked along the middle line by a groove, which is broader in front than behind, and lodges the basilar artery. The anterior surface presents two borders, an upper and a lower. The upper border, the longer, is convex, and arches beneath the crura cerebri. The lower border is almost straight, and is separated from tlie medulla oblongata by a transverse groove. The posterior surface is slightly concave from side to side, and forms part of the floor of tlie fourth ventricle. From the side of the pons the trifacial or fifth cranial nerve is seen emerging. In coronal sections the pons can be divided into an anterior or ventral region, and a posterior or tegmental region. The anterior region of the iwns is composed of transverse and longitudinal fibers. The superficial transverse fibers of the ante- 550 SURGICAL ANATOMY. rior region of the pons pass obliquely outward and l^aekward to the hemispheres of tlie cerebellum, forming the middle peduncles of the cerebellum. The deep transverse fibers of the anterior region of the pons are decussating filjcrs, wiiicli are crossing in the pons in passing from the cerebellar hemisphere of one side to the cerebral hemisphei-e of the opposite side. The longitudinal fibers are more deeply situated than the superficial transverse fibers, and are separated into bundles by the deep transverse fibers. They are the fibers of the pyramidal tracts of the medulla oblongata, passing upward to enter the crustte of the crura cerebri. In the posterior or tegmental region of the pons the chief structures observed are the tract of the fillet, which is seen nearest the anterior region, the formatio retic- ularis, the posterior longitudinal bundle, and the superior olivary nucleus. This region of the pons also contains the nuclei of the sixth and seventh cranial nerves, and a part of the nucleus of the eighth cranial nerve. While the importance of these nuclei has been clearly proved by cliiucal experience in cases of paralysis caused by hemorrhage occurring within the substance of the pons, as well as by microscopic investigation, they are not macroscopically visible. Hemorrhage into the pons is u-suallj' followed by coma and sudden death, par- ticularly if the hemorrhage is extensive, or if the blood escapes into the fourth ventricle. The decussation of the trifacial and the facial nerves takes place within the pons ; if, therefore, a lesion — as, for exami)le, a small lieraorrhage — occur above the point of the crossing of the fibers of the facial nerve, paralysis of the face and body on the side. opposite the lesion will occur; while if the lesion be immediately below the point of crossing, the paralysis of the face will be upon the side of the lesion and the hemiplegia upon the side opposite to the le.sion, thus giving rise to the condition known as crossed hemiplegia. Nerve fibers from the motor cortical area for speech run through the pons, and may be involved in a lesion of the pons, thus giving rise to aphasia. The Crura Cerebri, or Peduncles of the Cerebrum, are two large round bodies of white matter, about three-fourths of an inch, or two centimeters, in length, and broader in front than behind. They emerge from the upper border of the pons, whence they pass outward and forward to enter the under part of the hemispheres of the cerebrum. They pass through the superior occipital foramen in company witli the superior peduncles of the cerebellum, the basilar artery, and the ocuio-inotor and pathetic nerves. ' Crossing the lower surface of the crura just before they enter the hemispheres of the cerebrum, and adherent to them, ai'c the ()]>tic tracts, while in rclafioii with their inner borders are the oculii-MKitor nci'vcs, and with their nuter miirgiiis, tjie ])atiietic nerves. Dissection. — Divide one of (lie crura cerebri transver.sely, and a nuekais of PLATE CXXXVI, Pituitary body Optic n Tuber cinereum Corpora albicantia 3rd cranial n. 4th cranial n. Motor root of 5th cranial n Sensory root of 5th cranial n. Middle peduncle of cerebellum Anterior median fissure Pyramidal tract of medulla Olivary body I 2th cranial n Decussation of pyramids Optic tract Crus cerebri Optic thalamus External geniculate body nternal geniculate body Pons Varolii *. -^^^^ 6th cranial n iffifr-^ 7th cranial n. ff Jjl^^^r ^^^ rTf^niril n ^ loth cranial n. ^ 1 th cranial n. Lateral tract ngata PONS, MEDULLA, AND SUPERFICIAL ORIGINS OF CRANIAL NERVES. nf)'? THE MEDULLA OB LONG ATA. 553 gray matter — the locus nigcr, or substantia nigra — will be seen in the interior of the cms. Through tlie medium of this nucleus the crus ccrel)ri is divided into an upper or posterior portion and a lower or anterior jiortion. 'I'he upper oi- jiosterior porlidu is kniiwu as the tegnientuui, and the lower or nulerior [lortion as the crusta. The tegmentum of the crus cerebri is composed largely of the longitudinal fibers of the tegmental region of the pons, which proceed from the lateral tract and posterior pyramids of the medulla oblongata ; it also receives the fibers of the superior peduncle of the cerebellum. The tegmental fibers of the crus cerebri are sensory, and enter the hemisphere of the cerebrum below and through the optic thalamus, beyond which they form jiart of the corona i-adiata. The tegmen- tum contains two nuclei, the siihlluildinir hoihj and the tegmental or red nucleus. The aihuixture of gray and white matter of the tegmentum forms the formafio reticultiri.'t. The crusta is composed chiefly of the longitudinal fibers of the anterior region of the pons, which proceed from the anterior pyramids of the medulla. The fibers of the crusta are motor, and enter the hemisphere through the internal cap- sule, beyond which they form a part of the corona radiata. Tlie inner one-fifth of the crusta contains fillers which are passing to the pons from the prefrontal lobe. THE MEDULLA OBLONGATA. The Medulla Oblongata, or Bulb, the upper continuation of the spinal cord, begins at the decussation of the pyramids or the upper border of the atlas, and extends to the lower border of the pons Varolii, being not cjuite one and one-half inches, or 3.5 centimeters, in length. It increases in -width from below upward, and just below the 2:)ons it is about three-fourths of an inch, or two centimeters, wide. Its anterior or ventral surface rests partlj' upon tlie basilar portion of the occipital bone, and its posterior or dorsal surface is directed toward the vallecula of the cerebellum, which lodges part of the medulla. The anterior surface pre- sents, in the median line, the anterior median fissure, which is the continuation upward of the anterior median fissure of the spinal cord, which fissure is, however, interrupted by white fibers crossing from one side to the other and forming the decussation of the pyramids. On its posterior aspect, for one-half the length of the medulla, is situated the jiosterior median fissure or sulcus, the continuation of the corresponding fissure of the spinal cord. The medulla oblongata, like the spinal cord, is divided into an anterior, a lateral, and a posterior area. The anterior area is occupied by tlie anterior pyra- mids. The lateral area is occupied by the olivary Imdy and the lateral culumn. 554 SURGICAL AXATOMY. The jiosterior area contains tliu funit-ulus of Rolando, funiculus cuncatus, and funiculus gracilis, and in its uj)})cr }inrtinn is the restiforni liody. The Anterior Pyramids, or Pyramids of the Medulla Oblongata, are situ- ated between the anterior median and antero-lateral fissures. They are larger above, but are somewhat constricted and roun(]ed wliere they disajjpear beneath the sui^erficial transverse fibers of the pons. On separating the anterior pyramids below, bundles of fibers will be .seen decussating across the anterior median fissure. This decussation is produced by the innermost fibers of the pyramids, which are derived from the lateral or crossed pyramidal tracts of the spinal cord, and have reached the surface of the medulla oljlongata at this jioint by cutting through the anterior horn of the gray matter of the spinal cord, and pusliing aside the anterior pyramid.. The outermost fibers, wliicli form the smaller number of fibers of the pyramid, do not decussate, and continue downward as the direct pyramidal tract of the spinal cord ; the.se fibers decussate in the anterior or white commis.sure of the spinal cord. The decussation of the pyramids of the medulla explains the fact that in disease or injury of the motor cortex of the lirain the paralysis is found on the side of the lioily opposite to tlie lesion in the brain. The continuation of the anterior ground bundle of the spinal cord is not seen in the anterior ai'ea of the medulla oT)longata, as the fibers of that tract are de- pressed from the surface by the decussating bundles of the crossed pyramidal tract. The Olivary Body is an oval prominence on the medulla oblongata, situated to the outer side of the anterior pyramid. It is separated from the anterior pyramid by a narrow longitudinal groove, the hypoglossal sulcus, or antero-lateral furrow of the medulla, which is continuous with the antero-lateral fissure of the spinal cord. The olivary bodj- is limited posteriori}^ by the post-olivary sulcus. Like the anterior pyramid, it is broader above than below. It is separated from the piiiis l)y a deep groove, and is aljout one-half an inch, or twelve to fifteen millimeters, in length. Emerging from the hypoglossal sulcus or antero-lateral furrow arc the roots of the hypoglossal nerve. .Vrching below and over the olivary body, and emerging from tlie anterior meilian and antero-lateral fissures, several white bundles are seen — the superficial arciform fibers — which enter the restiform body of the same side. If an r}blique incision be carried through the olivary body, there will !>(_■ reveaU'il in its interinr a nucleus of gray matter, the corpus dentatum "f the (jlivary liody. This nueleus is arranged in the form of a hdlliiw ea|i-ule, and presents a com-dluled outline jiartly incomplete at its inner side. Tiiniugji this 0]ien part of the (•a})sule jia.sses a bundle of white fibers, the peduncle of the olivary body. 'I'lie Lateral Tract of the Medulla Oblongata is apparently the upward exten- sion of tlu^ lateral colunin of tjie spinal vovd, Init it does not contain tlie crossed PLATE CXXXVIl, Septum lucidum Anterior pillars of fo Peduricle of pineal body Pineal body Third ventricle Caudate nucleus Optic thalamus / /Tenia semicircularis estes ngitudinal median sulcus Eminentia teres Superior peduncle of cerebellum Superior medullary velum Middle peduncle of cerebellum Inferior peduncle of cerebellum Tuberculum acusticu Trigonum hypoglossi Ala cinerea Posterior median fissure of medulla oblongata'' Funiculus gracilis Conductor sonorus Striae medullares Lateral tract Funiculus cuneatus THIRD AND FOURTH VENTRICLES AND CORPORA QUADRICEMINA. 55G THE MEDULLA OBLONGATA. 557 in-ramidal tract of tlie cord, wliicli ciitrrs (lie ]iyrauiiilal tract of the medulla uMongata, and the direct cerebellar tract of the cord leaves it to enter the resti- form hody. It is lioiuided in front by the anierodateral furrow, and behind by the posterudateral hirrow. Emerging from the antii-odateral hirrow or hypoglossal sulcus are the roots of the hypoglossal nerve, and from the postero-lateral furrow the roots of the glosso-pharyngeal, pneumogastric, and spinal accessory nerves emerge. As it ascends, the lateral tract of the medulla becomes less marked, the greater jiurtion of it passing beneath the olivary body. Dissection. — To examine satisfactorily the remaining portion of the medulla oblongata, lift it out from the interval between the hemispheres of the cerebellum, and displace it forward, thus exposing the posterior surface of the medulla, as well as that portion of the floor of the fourth ventricle formed by the medulla. The Funiculus of Rolando, which lies posterior to the lateral tract and on the outer side of the funiculu.s cuneatus, is the u])ward continuation of a mass of gray matter — the substantia gelatinosa — which caps tlie posterior cornu of the gray matter of the spinal conh This funiculus presents an enlargement on a level with the lower end of the olivary body, called the tubercle of Rolando. The Funiculus Cuneatus lies between the funiculus of Kolando and the poste- rior median column or posterior pyramid. It is the widest and thickest of the columns of the medulla. Upjiosite the clava of the funiculus gracilis it forms a prominence called the cuneate tubercle. The Posterior Pyramid, or Funiculus Gracilis, the continuation upward of the posterior median column of the spinal cord, lies immediately to the outer side of the posterior median fissure. At the lower end of the fourth ventricle it swells out and forms a prominence, called the clava. The cuneate tubercle and the clava are produced by accumulations of gra}' matter known respectively as the cuneate and gracile nuclei ; almost all the fibers of the funiculus cuneatus and funic- ulus gracilis terminate in these nuclei. The Restiform Body appears to be formed l)y the funiculus gracilis, the funic- ulus cuneatus, and the funiculus of Rolando, passes outward and upward, and then enters the cerebellum, forming the inferior peduncle of the cerebellum. Since tlie fibers of the funiculus cuneatus and funiculus gracilis terminate in the cuneate and gracile nuclei, they can not, therefore, .strictly speaking, be said to be directly continued into the restiform bodies. The following are the more important of the sources from which the fibers of the restiform body are derived : "(1) From the lateral column of the spinal cord, through the direct cerebellar tract ; (2) from the convoluted nucleus of the olivary body of the opposite side ; (3) from the gracile and cuneate nuclei of the opposite side ; (4) frcjui the gracile and cuneate nuclei of the same side " (Cuimingliam). By the divergence of the restiform bodies the lateral 558 SURGICAL AXATOMY. boundaries of the lower part of the fourth ventricle are formed, while the apex of the lower triangle of the ventricle is situated at the point of separation of the two clava\ This divergence exposes the gray matter of the interior of the meduHa, which forms tlie floor of the lower portion of the fourth ventricle and is continuous with the gray matter of the spinal cord. Recapitulation. — Review the parts seen in studying the medulla from before backward. They are ; The anterior median fissure, the anterior pyramid, the hypo- glossal or antero-lateral fissure with the roots of tlie hypoglossal nerve, the olivary body, containing the corpus dentatum, the post-olivary sulcus, the lateral tract, the postero-lateral fissure with the roots of the glosso-pharyngeal, pneumoga.stric, and spinal accessory nerves, the funiculus of Rolando and its tubercle, the funiculus cuneatus with the cuneate tubercle, the funiculus gracilis with the clava, and the posterior median fissure. Function. — The medulla is described Ijy Ranney as " the true nerve center of animal life." Several of the cranial nerves have their primary, deep, or central origin whollj' or in j^art in the medulla. Some of the centers contained within the medulla are the respiratory, the vaso-motor, the cardio-inhibitory, the diabetic, and a salivary center. THE CEREBELLUM. Position, Size, and Connections. — The cerebellum, or little brain, lies beneath the occipital lobes of the cerebrum, behind the j^ons, and above and upon both sides of the medulla oblongata. It occupies the inferior occipital fossae, and lies beneath the tentorium cerebelli, which separates it from the ccrelirum. The surface of the cerebellum, like tliat of the cerebrum, is composed of gray matter, which is darker in color in the cerebellum, and arranged in laminse instead of in convolutions. The cei'ebellum measures from three and one-half to four inches, or from nine to ten centimeters, in its transverse diameter, from two to two and one-half inches, or from five to six centimeters, in its antero-posterior diameter, and aliout two inches, or five centimeters, in its vertical diameter at the thickest part. It is attached to the cerel)rum by tlie superior peduncles, to the pons by the middle peduncles, and to the nu'dulla oljlongata by the inferior peduncles of the cerebellum. Lobes. — Tlie cerebellum consists of two liemispheres and a central lobe, — the vermiform process, or vermis, — through the medium of which the hemispheres are niiitcil. The hemispheres are separateil inferiorly liy a comparatively wide and di( p median groove, tlu' vallecula, nr valley, wliich is occujiied in great jiart by tlie nie(]7 The superior peduncles of the cxTcbeUuni cuinu'ct the cerebt'lhini witli tin; cerehruni, and j)ass forward, forming the Uiteral boundaries of tlie anterior portion of the fourtli ventricle. Under the floor of the aqueduct of Sylvius the two superior i)eduncles decussate ; each peduncle then enters the opposite subthalamic region of the cerebrum, to reach the uptit' tiialamus and lenticular nucleus. The middle pcdunck's counect tliL' cerebellum with the pons. The inferior peduncles ave formed 'by the restiform bodies, and connect the cerebellum with the medulla oblongata and spinal cord. Dissection. — Carry a vertical incisiun through the center of the hemisphere of the cerebellum, to expose the white matter and gray nucleus. Interior Arrangement. — In the interior of the white matter of the cere- helhun is a gray nucleus, the corpus dentatum. The white matter sends processes into the lamiuce of the gray matter, which forms the surface of the cerebellum, and give rise to the appearance that has been termed the arbor viUe. The corpus dentatum of the cerebellum, like the nucleus of the same name in the olivary bod_v, is arranged in the form of a capsule presenting a zigzag outline which is open at the inner side. Through this open part, or hilum, of the capsule a bundle of white fibers passes to the sujierior peduncles of the cerebellum and the A'alve of Vieusseus. SECTIONS OF THE BRAIN. Having mastered the topography of the enccjihalon, together with its intra- ventricular aspect, in the study of whi(/li some of its parts were seen in horizontal sections, it will now be well to study coronal and sagittal sections, and so obtain a more accurate knowledge of the relations of tlie various parts of the enceph- alon. A sagittal section lies in a vertical longitudinal plane, running antei'o-poste- riorly, as if through the entire length of the brain through or parallel with the sagittal suture, hence it is so named ; a section of this kind is not, however, limited to the median line. A coronal section lies in a vertical transverse plane, running from side to side, at right angles to a sagittal plane ; this is also called a frontal section. A coronal section through the brain at the tips of the temporo-sjjhenoid lobes will traverse the anterior end of the lenticular nucleus of the corpus striatum, and one a short distance beyond this will pass through the anterior end of the caudate nucleus. A section passing through the optic commissure, or just behind it, will include the front of the optic thalami. A frontal section must, therefore, be made back of the optic commissure if it is to include both .sets of basal ganglia. A coronal section about midway between the optic commissure and the tijjs of 568 SURGICAL ANATOMY. the temporo-sphenoid lobes will not include the optic thalami. It will expose, from within outward, the septum lucidum, the lateral ventricle with the corpus callosum above it, the caudate nucleus, the internal capsule, the lenticular nucleus, the external capsule, the claustrum, the white matter, the island of Reil, and the fissure of Sylvius. The wedge shape of the lateral ventricle is |ilainly shown in this section, as is also the formation of its outer wall and part of its floor Vjy the sloping caudate nucleus. The lenticular nucleus is clearly separated into three portions, defined by fine white curved lines extending between them. AVhen these sections are made further back, the anteriorly situated j^arts become smaller, and finally disappear, while the more posteriorly situated parts gradually increase in size ; the caudate nucleus grows smaller and recedes toward the upper and outer angle of the lateral ventricle, while the optic thalamus occupies an increasing amount of the lower part of the outer wall of the lateral ventricle. Notable changes in the median line also occur, the fifth ventricle and the septum lucidum vanish, and the fornix and third ventricle appear instead, while the infun- dibulum, mammillary bodies, and posterior perforated spaces successively appear at the base. The crura cerebri at first appear to be separated, gradually coming closer, until they merge. The locus niger is distinctly visible, as are also the two adjacent divisions of the crura cerebri. The upper or front end of the pons comes into view, and at its upper edge the aqueduct of Sylvius appears. The velum interpositum, containing the choroid plexuses, becomes wider as the sections pass backward. The ta^nife semicirculares, the dentate fascite, the hippregma to the lambila. The bregma is situated at the junction of the coronal and sagittal sutures, and at the ])oint ■where a line, drawn perpendicular to Reid's base line at the j^reauricular fossa, crosses the median line of the cranial vault. The lambda is situated at the junction of the sagittal and lambdoid sutures, and about two and three-fourth iuchc.Sj or seven centimeters, above the external occii>ital jirotuljcrance. The coronal suture extends from the bregma downward, and slightly forward, towai'd the juni'tion of the zygoma with the malar bone. The lambdoid suture is situated at about the upper two-thirds of a line drawn from the lambda to the apex of the mastoid process of the temporal l)one. Ailditional sutures not conniionly present may exist in the vault of the cranium and be mistaken for fractures. These are the frontal suture, which extends forward between the halves of the frontal bone in the line of the sagittal .suture, the parietal fissure, a short suture which crosses the sagittal suture one inch, or two and one-half centimeters, anterior to the lambda, and the transverse occipital fissure, which is a suture situated in the occipital bone near the level of the external occipital protuberance. The Temporo-maxillary Articulation is the joint situated between the con- dyle of the inferior maxilla below, and the anterior part of the glenoid fossa and the eminentia articularis above. It is a ginglymo-arthrodial articulation, or hinge joint, modified to allow gliding movement. The ligaments of the temporo- maxillary articulation are the capsular ligament and the intorarticvilar tibro- cartilage. The joint is strengthened by the spheno-mandibular and stylo-man- dibular ligaments. The capsular ligament is thin, especially at its anterior and inner portions. It is attached above to the margins of the articular surface formed by the eminentia articularis and anterior portion of the glenoid cavity of the temporal bone, and below to the neck of the lower jaw. Its external ]iortion is much stronger than the remainder of the cap.sule, and is termed the external lateral liga- ment. 574 SURGICAL ANATOMY. The external lateral ligament is attached above to the lower margin of the zygoma ami the tuljercle of tlie zygoma, its fibers jjassiiig downward and back- ward to be attached below to the outer surface and posterior margin of the neck of the lower jaw. The interarticular fibro-cartilage is situated between the articular surfaces of the bones entering into the formation of the joint. Through conformation to these surfaces its upper surface is concavo-convex from before backward and convex laterally', and the posterior portion of its under surface is concave, to fit the con- dyle. It is thinner at its center, and thickest posteriori}^, where it acts as a buffer and protects the thin bone of the glenoid fossa. Its margins are attached to the capsular ligament, and some of the fibers of the tendon of the external pterygoid muscle pass between the fibers of the anterior portion of the capsular ligament, to be inserted into the anterior margin of the interarticular fibro-cartilage. The synovial membranes are two in number, the superior synovial mem- brane being separated from the inferior by the interarticular fibro-cartilage. When the interarticular fibro-cartilage is perforated, the two synovial sacs com- municate. The spheno-mandibular or internal lateral ligament is attached above to the spine of the greater wing of the sphenoid bone and adjacent part of the temporal bone, and below to the spine of Spix, or mandibular spine, which is situated on the inner surface of the lower jaw, below and internal to the inferior dental for- amen. The internal lateral ligament is separated from the temporo-maxillary joint and lower jaw by the internal maxillary artery and vein, the middle meningeal artery, the external pterygoid muscle, the inferior dental vessels and the inferior dental nerve. Its lower extremity is pierced by the mylo-hyoid nerve. The stylo-mandibular or stylo-maxillary ligament is a jjart of that process of the deep cervical fascia wliich dips beneath the parotid gland. It extends from the stj'loid process of the temporal bone to the angle and postei'ior margin of the ramus of the lower jaw, separating the parotid from the submaxillary gland. Blood Supply. — From the temporal, middle meningeal, and ascending pharyngeal arteries. Nerve Supply. — From the auriculo-temporal and masseteric branches of the inferior maxillary nerve. .Movements. — Rotation of the condyle around a transverse axis occurs when the inDutli is opened or closed, and gliding forward of both the condyle and the interarticular cartilage A\hcn the mouth is widely opened. If the mouth is opened too wid( ly, as in a convulsive yawn, the condyle and interartii'ular fibro-cartilage may be completely or incompletely dislocated forward, and locked either in front of or uiion the eminentia articularis. In closing the mouth the cartilage and condvle PLATE GXllll. External lateral lig Capsular lig. ' '' Styloid process Stylo-maxillary lig. Stylo-hyoid lig. TEMPORO-MAXILLARY ARTICULATION-EXTERNAL VIEW. 576 PLATE CXLIV, Capsular lig Styloid process nternal lateral liar Stylo-hyoid lig Stylo-maxillary lis f!_ II-. ■',7 TEMPORO-MAXILLARY ARTICULATION-INTERNAL VIEW. 0( / JOIXTS OF THE HEAD AM) NECK. 579 glide backward, and the condj-le rotates on the cartilage in the reverse direction. These movements result in a combination of a hinge movement of the condyle with fore-and-aft gliding movement of the interarticular iibro-carlilagc (iliding movement of the interarticular fibro-cartilage forward occurs when the lower jaw and chin are thrust forward. Kutation of the condyle around tlic vertical axis of the neck of the lower jaw, associated with oblique gliding of the inter- articular fibro-cartilage on the glenoid fossa, occurs in tlic oljlicjuc movements of tlie lower jaw in mastication. The Joints of the Neck are those of the cervical portion of the spinal column, which have been described in volume i. Dislocations. — Dislocation of the bones of the vault and base of the skull is almost entirely limited to the young skull. Such an accident rarely occurs in the adult skull, the firm union and overlapping of the bones preventing disloca- tion of these articulations. The scjuamous suture has been separated by dis- location of the temporal bone. Fractures in the line of the coronal, sagittal, and lambdoid sutures have occurred. Dislocation of the lower jaw is of comparatively rare occurrence, and is usually forward and bilateral. Forivard dislocation occurs M'hile the mouth is wide open, as during convulsive yawning, manipulations of dentists, or from blows on the chin. Only a small amount of force is required at such a time to carry the condyle from a position just behind, to a point upon or immediately in front of, the summit of tlie eminentia articularis. The anterior portion of the capsular ligament is torn ; the interarticular fibro-cartilage is usually dislocated with the condyle. The condyle is retained in its abnormal position by the upward traction of the temporal, masseter, and internal pterygoid muscles. Backward dislocation of the lower jaw may follow a blow on the chin, and the condyle may fracture the bony portion of the external auditory meatus or be driven into the cranial cavity. Excisions. — Excision of the upper jaw is usually performed for malignant disease, as sarcoma or carcinoma of the maxillary sinus or antrum of High- more. Generally but one superior maxilla is removed, although both upper jaws have been removed in one operation. In excising the superior maxilla several anatomic facts are to be remembered. The upper jaw is in reality a shell of bone which envelops the maxillary sinus, forms a large part of the floor of the orbit, roof of the mouth, external wall of the nasal fossa, anterior wall of the spheno-maxillary fossa and pterygo-maxillary region, and bony basis of the front of the face below the infra-orbital ridge. Its strongest portions are the malar, alveolar, and palatal processes. In the operation of excision of the superior maxillary bone the inferior tur- 580 SURGICAL ANATOMY. biuated bone, jmrt of the malar bone, part of the palate bone, and the superior maxillary bone, except the ujDper part of its nasal process, are removed. In the method of excision which is most commonly practised, — that is, by a median incision, — the first incision is begun one-half of an inch, or slightly less than one and one-half centimeters, below the inner canthus of the eyelids. It is carried downward along the groove between the nose and face, around the ala of the nose, below the base of the nose to the median line, and thence through the median line of the upper lip. This incision divides skin, superficial fascia, some of the muscles of expression, the angular artery and vein, the lateral nasal arterj', the arteiy of the nasal septum, the superior coronary artery, and branches of the infra-orbital and facial nerves. The second incision is carried from the point at which the first incision was commenced outward along the infra-orbital margin to a point over the malar bone. This incision divides a few insignificant blood-vessels. The tissues of the flap out- lined are now quickly reflected outward, removing all of them down to the bone, not considering the periosteum. In elevation of this flap the infra-orbital vessels and nerve are divided. The fibro-cartilaginous lateral portion of the nose is detached from the supe- rior maxilla, and the base of the nasal process of the superior maxilla is severed with a fine saw or a chisel. The periosteum is divided along the infra-orbital ridge, and elevated from the floor of the orbit, at the same time detaching the origin of the inferior oblique muscle of the eyeball. The inner part of the floor of the orbit is then divided with a small chisel. The malar bone is next severed at its middle with a small saw or chisel, and in a line which extends obliquely down- ward and outward. The saw is carried through the floor of the orbit until it reaches the spheno-maxillary fissure. The malar bone can be divided with strong bone forceps, which are not allowed to extend into the spheno-maxillary fissure. If the forceps are inserted too deeply into the fissure, the internal maxillary artery may be severed. The central incisor on the diseased side is extracted, the muco-periosteum of the floor of the nose is divided close to the nasal septum, the muco-periosteum of the hard palate is severed in the median line, and the soft palate is thoroughly separated from the hard palate. "With a slender saw introduced through the nose the hard palate is divided close to the nasal septum. With one blade of the forceps at the infra-orbital ridge and the other at the alveolar process, the jaw is grasped with lion forceps, and loosened from the remain- ing attachments. This procedure fractures the vertical plate of the palate bone, and detaches the jaw from the pterygoid process of the sphenoid bone. The vessels ruptured or divided in removing the superior maxilla are PLATE CXLV, Externaf pterygoid m-^ atysma, digastric, mylo-hyoid, enio-hyoid, and gento-hyo-glossus muscles DOUBLE FRACTURE OF LOWER JAW AT MENTAL FOR.AMINA. FRACTURES OF LOWER JAW, 581 JOINTS OF THE JIEAD AND NECK. 583 braiii-lies of tlie tliird portion of tlie internal maxillary artery. They are the alveolar, iniVa-orbital, posterior palatine, pterygo-palatine, and naso-palatine arteries, or some of their branches. The application of the actual cautery may be required to check hemorrhage. The cavity may be packed with gauze, and the wound in the skin is closed. The gauze is subsef[uently removed through the mouth. Excision of the lower jaw is i)eri'ormed for the removal of malignant growths of that bone. Usually but half of the bone is excised. Segments of the lower jaw are removed in extirpation of benign tumors of that bone. The incision is carried from the attached margin of the lower lij) down the middle of the chin to the lower margin of the jaw, thence just below and parallel with the body of the jaw to the angle, and thence upward along the posterior margin of the ramus of the lower jaw to the level of the lobule of the ear. In making this incision the facial artery is secured between ligatures before it is divided. The skin, superticial fascia, platysma myoides muscle, and deep fascia are divided ; the parotid, submaxillary, and sublingual glands and Stenson's duct must be avoided. Beginning at the symphysis, the soft tissues are detached from the external surface of the bone with a periosteal elevator. The depressor labii inferioris, depressor anguli oris, buccinator, and masseter muscles are thus separated from the bone. After extraction of one of the incisor teeth the bone is divided with a small saw. The divided end of the bone is next drawn outward, and the mylo-hyoid muscle and mucous membrane of the mouth are divided close to the bone, being careful to avoid injuring the sublingual or submaxillary gland or the lingual nerve. The internal pterygoid muscle is detached from the bone with a periosteal elevator, and the internal lateral ligament of the lower jaw and inferior dental vessels and nerve are divided. The jaw is now depressed, to bring the coronoid process into view. This pro- cess is then divided with a chisel and a mallet, and dissected out afterward, or the tendon of the temporal muscle is severed with curved scissors. The tendon of the external pterygoid muscle is divided with scissors, or detached with a periosteal elevator. The capsular ligament is divided, and, after severing some few remaining attachments, as the stylo-maxillary ligament, the bone can be removed. After bleeding has been checked the wound is closed. The structures to be avoided in this operation are the three salivary glands, Stenson's duct, the buccal and supra-maxillary branches of the facial nerve, the lingual and auriculo-temporal nerves, the external carotid, temporal, and internal maxillary arteries, and the temporo-maxillary and internal maxillary veins. The 584 SURGICAL ANATOMY. vessels which must be divided are the facial, inferior labial, mental, mylo-hyoid, inferior dental, and masseteric arteries and veins. Excision of the condyle of tJie lower jaw is performed most commonly for disease of the temporo-maxillary articulation causing impaired movement in that jaw. A vertical incision is carried from the zygoma downward over the condyle of the lower jaw, to a point just above the position of the transverse facial artery, which is one centimeter, or less than one-half of an inch, below and parallel with the zygoma. A second incision is carried forward along the lower margin of the zygoma for one inch, or 2.5 centimeters. The flap thus outlined is reflected for- ward and downward, avoiding the temporal branches of the facial nerve. The posterior fibers of the masseter muscle are detached from the zj'goma, and the capsule of the temporo-maxillary joint is opened. The neck of the condyle is divided with a chisel or a small saw, the condyle being firmlj' held with a small hook. The condyle is twisted out of the glenoid fossa, and the external pterj^goid tendon and capsular ligament are divided. The instruments are kept close to the bone, to avoid injuring the temporal, internal maxillary, and masseteric vessels, the auriculo-temporal and masseteric nerves, and the parotid gland. Development of the Bones of the Skull. — The bones of the vault of the cranium are developed in membrane, and those of the base of the skull are formed in cartilage. Just before birth the bones of the vault are imperfectly ossified at their margins, so that they are joined by membrane instead of by sutures. This condition of the bones allows diminution in the diameters of the fetal skull at birth by overlapping of the bones of the cranial vault. At birth the bones are incompletely ossified at the angles of the parietal bone ; these meml)ranous areas are called fontanels. The posterior fontanel is triangular in shape, is situated at the lambda, and closes during the first few months after birth. The anterior fontanel is quadrilateral, is located at the bregma, and closes during the latter half of tlie second year. Tlie antero-lateral fontanels, situated at the anterior inferior angles of the l^rietal bones, and tlie postero-lateral fontanels, situated at the posterior inferior angles of the parietal bones, close .soon after birth. Imperfect or delayed ossifica- tion at the fontanels occurs in hydrocephalus. Fractures of the Skull. — Tlie bones of the skull in young children are not readily iVacturcd. AVlicn force is applied to tlie vault of the skull of a young infant, it is merely indented, ossification l)eing so incomplete that the bones are flcxihlc. FRACTURES OF THE HEAD AXD NECK. 585 The adult skull is not readily liactuivd, because its curves diffuse and diminish the breaking iorce, and, being composed of three tables of dilferent consistence, its strength and elasticity are much enhanced. Other cduditions which lessen the danger of fracture of the vault of the cranium are : The mobility of the scalp proper, the rounded shape of the cranial vault, and the mobility of the head. As age advances and the bones become less porou.s, less elastic, and, at the fortieth year, the sutures begin to be obliterated by ossification of the inter.'^utural membrane the skull is more readily fractured. JOillirr the external table or the internal table may l)e IVaetured without injury to the other table, but both tables are usually traversed by the fracture. On account of its brittleness and the diffusion of the foi'ce in pas.sing through the bone, the inner table is much more splintered than the external. In depressed fractures of the vault the inner table may not be broken, the outer table being merely driven into the diploe or one of the frontal sinus Fractures of the vault of the skull are due to direct violence. A fracture of the vault resulting from dilluse application of force, as in a fall upon the head, usually extends to the base of the skull by the shortest route, regardless of sutures or thickness of the bones traversed. This is more likely to occur if the fracture be linear. Fractures of the frontal region extend into the floor of the anterior cranial fossa, those of the parietal region into the floor of the middle cranial fossa, and those of the occipital region into the floor of the posterior craliial fos.sa. Fractures of the base of the skull are caused by extension of a fracture fi-om the vault of the skull and by direct or indirect A'iolence. Fractures of the base by direct violence have been caused b}' foreign bodies having been driven through the roof of the orbit, nose, or pharynx. Fractures of the base by indirect violence usually result from the body falling ujion the feet, knees, or buttocks, and fnim the upper part of the spinal column being driven against or through the occipital bone. In blows at the root of the nose the cribriform plate of the ethmoid bone may be fractured, and in a fall upon the chin the condyle of the lower jaw may be driven through the base of the skull at the middle cranial fossa. The cribritbrm plate of the ethmoid bone has been In'oken by counter-stroke by a Ijlow in the occipital region. In fracture of the base of the skull at the anterior cranial fossa blood may enter the orbit and produce a subconjunctival ecchymosis, or blood and cerebro- spinal fluid may escaj^e from the nose through the anterior nares or posterior nares and mouth. The blood escaping into the orbit is derived from ruptured menin- geal vessels, anterior or posterior ethmoid vessels, and ophtbalmir arteiy or vt'in ; that entering the nose escapes from the anterior or jiosterior ethmoid vessels, and the vessels of the nasal mucous memlirane. In fracture of the cribritbrm plate of 586 SURGICAL AXATOMY. the ethmoid bone rupture of the olfactory nerves niaj' cause loss of the sense of smell. In fractures at the middle cranial fossa blood and cerebro-spinal fluid may escape from the ear. To permit cerebro-spinal fluid to escape in this manner, the arachnoid, dura mater, bone and mucous membrane of the wall of the tym- panum, and membrana tympani must be ruptured. In fracture of the base at this fossa the cavernous sinus may be ruptured, and if the fracture extend across the petrous portion of the temporal bone, the superior petrosal sinus, and the facial and auditory nerves may be injured. Laceration of the facial nerve causes paralysis of the muscles of expi'ession and of the buccinator muscle ; laceration of the auditory nerve causes deafness. In fractures of the base of the skull at the posterior cranial fossa blood may be extra vasated into the tissues of the najse or posterior triangle of the neck. The symptoms of fracture of the skull are chiefly those of compression of the brain, produced b}' extravasated blood which arises from rupture of the meningeal vessels, sinuses of the dura mater, and diploic veins. Fractures of the Bones of the Face are the result of direct violence. In fracture of the nasal bones emphysema of the soft tissues may occur. In fracture of the lacrymal bone obstruction of the nasal duct may cause the tears to flow over the cheek, and laceration of the muco-periosteal wall of the duct may induce emphysema of the soft tissues. In comminuted fracture of the zygomatic arch fragments of bone driven into the temporal muscle may interfere with the move- ments of the lower jaw in mastication. Fracture of the bone of the upper jaw may cause profuse hemorrhage from a ruptured infra-orbital, superior dental, anterior palatine, or posterior palatine artery. Fracture of the lower jaw occurs more frecjuently than fracture of any other bone of the face. It is usuall)' broken b}' direct violence. In fractures of the neck of the lower jaw the condyle is drawn forward by the external pterygoid muscle. Imperfect apposition and persistent mobility of the fragments may induce excessive formation of callus, which may subsec|uently cause more or less ankylosis of the temporo-maxillary articulation. In fracture of the ramus of the bone there is slight displacement of the fragments, as the massetcr and internal pterygoid muscles act as splints. In fracture in front of tlie attachment of the masseter muscle the posterior fragment is drawn upward by the masseter, temporal, and internal pterygoid muscles ; if the plane of fracture extends obliquelj' backward and outward, the posterior fragment is also drawn inward by the internal pterygoid muscle. The anterior fragment is carried downward by the fracturing force, the platysma myoides, digastric, mylo-hyoid, genio-hyoid, and genio-hyo-glossus muscles. In donlilc fracture at the mental foraniiun the middle fragment is carried downward SURFACE AXATOMY OF THE CRANK 'M. 587 and l)ack\vanl by its wiM^lit, ami tliu digastric, inylo-hyoid, geuio-hyoid, and genio-hyo-fjlossus muscles. Tliis displacement allows the base of the tongue to fall against the epiglottis, and thus asphyxiation may be produced. SURFACE ANATOMY OF THE CRANIUM. The Cranium is that poi'tion of the head which extends from the lower margin of the forehead in front to the upper extremity of the neck behind, from ear to ear laterally, and along the base of the brain-case below. The base of the brain-case is represented by a line which extends from the eyebrows, througli the external auditory meatus, to the najie of the neck. The covering of this area, with the exception of that of the fore- head and part of tlie temporal regions, constitutes the scalp. The Scalp is covered by hair, which is more or less abundant. At the junction of the middle and posterior thirds of the sagittal suture can be seen a dividing point of the hair, from which it falls radially in all directions. It is at this jwint that baldness usually begins. The density of tiie scalp is well marked. The integument is closely connected with the cranial or occipito-frontalis aponeurosis, on account of which attachment many persons can readily move the scalp by the alternate contractions of the occipital and frontal divisions of the muscle. The scalp is lacking in elasticity, especially in the back part. In peeling the scalp back, during postmortem examinations, it sometimes tears, and in the subsequent sewing stitches pull tln'ongh if drawn very tightly. In this respect the scalp differs remarkal^ly from the skin of other regions of the bod}'. The skin else- where has more elasticitv and allows much stretching before it tears. Tumors 588 SURGICAL ANATOMY. of the scalp are movable if above the cranial aponeurosis ; when below it they are immovable. The arteries of the scalp are the frontal, which ascends near the median line ; the supra-orbital, which is found above the supra-orbital notch and for some distance up the forehead ; the anterior branch of the temporal artery (often very tortuous), found about one and one-quarter inches behind the external angular process of the frontal bone ; the posterior branch of the temporal, which runs above and in front of the ear ; the posterior auricular, above and behind the ear ; and the occipital, distinguishable about midway between the mastoid process and the external occipital protuberance. In examining the head as a whole, it will be noticed that the two sides are not symmetric — one side almost always having larger dimensions than the other. Although the general conformation of the skull cap is a fair index of its contents, it does not follow that every minute change in form of the brain has its effect upon the skull, as is claimed by many phrenologists. The cranial bones are the frontal, tAvo parietal, two temporal, the occipital, the sphenoid, and the ethmoid. In the adult they are immovably connected with one another, the lines of their junctions being termed sutures. In infancy the frontal bone consists of two portions ; these coalesce very early in life, the line of union being the frontal suture. The two parietal bones are joined by the sagittal suture. Tlie course of the two sutures, the frontal and sagittal, corresponds to a line drawn from the root of the nose, directly backward over the median line of the vault of the skull, to the external occipital protuberance. In this line, within the skull, are the .superior longitudinal sinus and the longitudinal fissure of the cerebrum. The parietal bones are joined to the frontal bone by the coronal suture, and to the occipital bone by the lambdoid suture. About one inch anterior to tlie center of a vertical line drawn directly over the skull from one exter- nal auditory meatus to the other, and at the junction of the coronal with the sagittal suture, is the bregma, which is the situation of the anterior fontanel of the infant. The coronal suture corresponds to a line drawn from the bregma to the middle of the zygomatic arch. The lambdoid suture is represented by a line drawn from tlie posterior border of the base of the mastoid process to a point midway between the bregma and the external occipital protuberance. The lambda is the point of junction of the sagittal and lambdoid sutures. This is the .site of the posterior fontanel in infants. The pterion — the junction of the anterior inferior angle of the parietal, the frontal, tlni tciniioral, and the greater wing of the sphenoid bone — is found about one and one-half inches behind the external angular process of the frontal bone, and about the same distance above the zygoma. The superciliary ridges commence on each side of the glabella, which is PLATE CXLVl. Iregma CRANIAL LANDMARKS AND LINES OF CEREBRAL FISSURES. 589 SURFACE ANATOMY OF THE CRANIUM. 591 the elevation above the root of the nose, and extend outward in a gentle curve, gradually becoming less prominent. The superciliary ridges mark the location of the sinuses of the frontal bone, but may vary greatly, generally because of the difference in size of tlie frontal sinuses. They are small in females and absent in children. Although the size of the ridge may be an indication of the size of the frontal sinus, yet this does not always hold good, as we may find a large ridge with but little development of the sinus ; and vice versa. Some of the Australian abor- igines have very small sinuses, but large ridges, due to great thickness of the bone. Above the superciliary ridges are found the frontal eminences. They are slightly convex elevations wliich mark tlie original centers of ossification in the two frontal bones. Their prominence is generally considered as an index of the amount of intellectual capacity of the individual. The increase in the develop- ment of the skull as a whole causes the frontal bones to become upright, and thus makes the frontal eminences more prominent. Immediately behind the external ear is the mastoid process of the temporal bone. It is but rudimentary in infancy, and develops later in life. It extends downward for about an inch below the external auditory meatus, and projects forward slightly under it. The digastric fossa is internal to the mastoid process. The body of the process is honeycombed witli air-cells, which are connected with the middle ear. At times these become so inflamed that trephining or incision is necessary to afford relief. The incision should be made in the hairless space behind the ear (Wilde's incision). A line connecting the tips of the two mastoid processes would pass through, or immediately under, the condyles of the occipital bone. About half an inch above and three-quarters of an inch behind the posterior border of the mastoid process is the asterion — the junction of the lambdoid and squamous sutures. The external occipital protuberance (inion) is distinctly felt in the median line at the posterior part of the head, at the junction of the skin of the neck with that of the head. It is the thickest part of the vault of the skull. From it the superior curved lines of the occipital bone extend laterally and give attachment to some of the muscles which support the head. The external occipital protuberance marks the position of the torcular Herophili, or the con- fluence of the superior longitudinal, two lateral, straight, and occipital sinuses. Above the superior curved lines the general contour of the .skull can be readilj' seen, as the covering is composed of thin structures. Below these lines, however, the skull recedes to a considerable extent, the space being filled in with the strong muscles and fascige of the neck. In the region of the occiput there is occasionally found a bulging of the membranes of the brain (meningocele), or of the brain itself (encephalocele) ; in these cases there is defective ossification of the 592 SURGICAL ANATOMY. occipital bone, and the tumor caused by the protruding cranial contents is always in the median line. The parietal eminences which mark the position of the centers of ossification in the parietal bones are readily distinguishable on the sides of the skull aljove the ears. They are much more marked in infancy, gradually becoming rounded and less prominent. Anterior to the parietal eminences, and running along the sides of the head, are the two temporal ridges which limit the temporal fossa) above and give attachment to the temporal fascia. They commence at the external angular process of the frontal bone and arch upward, backward, and then downward, to become lost on the posterior roots of the zygomatic process. The point where the coronal suture is crossed by the temporal ridge is known as the stephanion. It is about one and one-quarter inches above the pterion. The middle meningeal artery passes upward on the anterior inferior angle of the parietal bone, and is found by trephining an inch and a half behind and about an inch above the external angular process. The course of the superior longitudinal sinus is indicated by a line drawn over the median line of the top of the head, or from the root of the nose to the external occipital protuberance. The course of the horizontal portion of the lateral sinus is shown by the posterior part of a line drawn from the external occipital protuberance to a point one inch above the external auditory meatus. The sinus turns downward and becomes the sigmoid sinus at the point where a vertical line drawn through the posterior border of the base of the mastoid process crosses the line for the horizontal portion. The course of the sigmoid sinus is marked by a line dra-mi from the point of termination of the horizontal portion of the lateral sinus to the tip of the mastoid process. SUBFACE ANATOMY OF THE FACE. The appearance of the face in health and disease deserves attention from the physician. In infancy, owing to greater abundance of subcutaneous fat and the lack of development of the muscles of expression, the face is full and round ; the relatively greater development of the brain and sense organs causes the upper portion of the face to be broader than the lower ; the nasal fossae are shallow, and the maxillary bones are small. In old age the subcutaneous fat largely disappears and the integument becomes wrinkled and thinner. Not infrequently there are observed areas of SURFACE ANATOMY OF THE FACE. 593 thickeiu'd, browiiisli c']ii(lornus (keratosis senilis), particularly in persons much exposed to the weather. After middle life there is a tendency to dilatation of the superficial vessels, especially on the nose and cheeks. The absorption of the alveolar processes and loss of the teeth cause the charac- teristic aiipearance of the mouth in old age ; the lips being inverted, the red border becomes narrt)\\er, i\nd when the mouth is closed the chin is drawn toward the nose. The more or less characteristic changes produced by disease can not, of course, be described here ; allusion may be made to the waxy hue of the skin in certain renal affections, the cyanosis in grave cardiac lesions, the hectic flush associated with J lulmonary tuberculosis, and the " facies hippocratica." In the last named the sunken temples and cheeks ; the pointed nose and chin ; the dull, leaden hue ; the few drops of perspiration, and the cold, clammy skin portend the near approach of death. The supra-orbital arches are readily recognized as the dividing line between the forehead and the face. They are strong arches which form the upper boundary of the circumference of the orbit. They are covered by the eyebrows. Internally they end in the internal angular ])rocesses of the frontal bone, which articulate with the lacrymal bone and the nasal process of the superior maxilla. Between the two internal angular processes, at tlie fronto-nasal suture, a meningo- cele or an encephalocele sometimes appears. Externally, the supra-orbital arches terminate in the external angular processes, which articulate with the malar bone. Immediately below the supra-orbital arches are the eyes. They and their lids present points of interest. In size the eyes do not vary much in different indi- viduals, the apparent difference being due to the variations in the length of the palpebral fissure, which thus permits a larger or smaller portion of the ocular surface to come into view. The palpebral fissure is the aperture between the edges of the two lids, and extends from the inner to the outer canthus. The fissure is not, as a rule, exactly horizontal, the outer canthus being generally a little higher than the inner. By everting the eyelids, the tarsal cartilage may be felt as a thickened portion of the lid. The vertical arrangement of the Meibomian glands in the tarsal cartilage can also be made out. During sleep the eyeball turns upward and inward, thus sheltering the pupil behind the base of the upper lid under the supra- orbital arch, the lower lid, at the same time, moving upward and somewhat inward. In fainting sjjells, or during sleep, the white sclerotic of the eyeball shows through the jialpebral fissure. This ftict is often of value in detecting a sham sleep or a sham faint ; when, after gently lifting the upper lid by pressing upward and against the eyeball, if the pupil is in view, the patient is not asleep. S— 38 594 SURGICAL ANATOMY. The puncta lachrymalia are readilj^ discernible near the inner canthus, the lower being the larger and more external. The introduction of a probe into the lacrj'inal canaliculus should be preceded by drawing the lid outward, thus straightening the canal. The tendo oculi can be felt after drawing the eyelids outward, or forcibly clos- ing the eye. Immediately behind this is the lacrymal sac. If a knife were pushed backward just below tlie tendo oculi it would enter the sac, with the angular artery and vein on the inner side of the puncture. A probe passing through this opening into the sac, and then downward, slightly outward, and backward, would enter the nasal duct and appear in the inferior meatus of the nose. Tension upon the tendon, as in closure of the eyelids, compresses the sac, with which it is closely connected, thus emptying the sac and forcing the tears which have collected at the inner angle of the eye down the nasal duct. The nasal duct extends from the inner angle of the eye to the inferior nasal meatus, just under the inferior turbinated bone. It is about three-quarters of an inch in length, and constricted in its middle. The lower opening in the nasal mucous membrane is a slit, luit there is cjuite a large opening in the dry bone. When the lower end of the duct lies in the lateral wall of the meatus instead of in its roof, greater difficulty is experienced in passing a probe into the duct. The lower border of the orbit (infra-orbital margin) lies immediately below the eyeball and is formed by the superior maxillary and malar bones. It can be readily felt throughout its entire extent. The glabella is a flat, triangular eminence situated between the two internal extremities of the superciliary ridges. Immediately below the apex of the glabella is found the prominence of the nose formed by the nasal bones. The form of the nose and much of the general expression of the face are due to the size and form of the nasal bones. The difference in these bones accounts for the variations we find in the various races. In the Mongolian and Ethiopian the nasal bones are flat and broad at their base, and thus form the flat nose which is so characteristic of those races. In the Caucasian race, however, the nasal bones are narrow and elongated as well as prominent at the bridge. The nose is rigid at its root and base as far as its middle, beyond which it is cartilaginous and flexible. The intimate adherence of the skin to the nasal cartilages, which are attached to the lower ends of the nasal bones, makes furuncles or erysipelas in this region exceedingly painful, liecau.se of the lack of cutaneous elasticity. The lower end (if the nose is open and dividcil into the two anterior nares by tlie nasal septum and the coluwna. It .should not be forgotten that the nose is attached lower than the floor of its cavity ; so that it must be elevated when the interior is to be inspected. SURFACE ANATOMY OF THE FACE. 595 Below the nose is seen the mouth, which is the upper opening of the gastro- intestinal tract. The lips contain muscles and vessels, and play a large part in the general expression of the face. In the living suhjcct the pulsations of the superior and inferior coronary arteries can be easily felt by holding the lips between the finger and the thumb. In the operation for harelip these arteries are divided, the ensuing hemorrhage being easily controlled by pressure with the finger and thumb. Although the aperture between the lips is generally spoken of as the mouth, it must be remembered that the mouth extends backward from the lips to the pharynx. Below the lips can be found the prominence of the symphysis of the lower jaw. The lower jaw is easily felt from the symphysis to the condyle, where it articulates with the temporal bone. By slight pressure along the bone the alveolar border, in which the teeth are set, can be readily distinguished. In passing the finger backward along the lower border of the body of the jaw the angle, which is at the junction of the body with the ramus, can be distinguished. In front of the angle is a depression through which passes the facial artery, the pulsation of which can be detected in the living subject. The condyle of the lower jaw is felt in front of the tragus of the external ear and below the zj'gomatic arch. When the mouth of a living person is opened, the condyle can be felt leaving the glenoid fossa and advancing upon the eminentia articularis. This forward motion of the condyle affords a freer access to the external ear, which can be demonstrated by passing the little finger into the external auditory meatus and opening and closing the mouth. In the supra-orbital margin, at the junction of its inner with its middle third, is the supra-orbital notch, or foramen, which gives passage to the supra-orbital vessels and nerve. The mental foramen is found in the lower jaw, opposite the second bicuspid tooth ; it gives pas.sage to the mental vessels and nerve. In a line drawn between the supra-orbital notch and mental foramen, and just below the infra-orbital margin, is the infra-orbital foramen, which gives passage to the infra- orbital vessels and nerve. These nerves are derived from the fifth cranial nerve. Quite frecjuently accessor}' foramina are found external to the constant ones, and usually transmit a portion of the nerve which commonly passes through the normal foramen. These anomalies, especially on account of their frequency, are of considerable significance in the treatment of neuralgias by nerve section. The •anomalous openings occur most frequently in connection witli the supra-orbital, the infra-orbital, or the mental foramen, in the order named, and upon the right side. At times a deep groove extends for several inches upward from the accessory supra- orbital foramen and about a finger's breadth internal to the temporal ridge. Failure to obtain relief in some cases of neuralgia, after section of the nerve which 596 SURGICAL ANATOMY. passes through the normal foramen, may be due to an accessory nerve, instead of to central disease or affections of the ganglia connected with the parent stem. Continuing outward from the external angular process is the zygomatic arch, formed by the malar bone and the zj'gomatic process of the teniiporal bone. The anterior part of the arch is flat and broad, and forms the prominence of tlie cheek, or the " cheek bone." Posteriorly, the zygomatic arch terminates in front of, and just above, the external auditory meatus. On account of the attachment of the dense temporal fascia to the upper border of this arch, the lower border is more easily distinguished. The zygomatic arch forms a dividing line between two depressions. These are generally filled with fat in the healthy individual, and, therefore, are not markedly evident. As soon as a wasting disease begins to tax the organism, the fat above the zygoma is absorbed, and this bony arch becomes much more prominent ; as the wasting progresses, the masseteric depression can be plainly seen, and, at the same time, the fat in front of the anterior margin of the masseter muscle and below the anterior half of the malar bone disapfjcars, with resultant sinking of the cheeks. The arteries of the face are the temporal, between the ear and zygoma, and the facial, on the body of the lower jaw just in front of the masseter muscle, at the angle of the mouth, and passing along the naso-labial fold and side of the nose to the inner angle of the eye. The facial A^ein runs straight across the face from the inner canthus of the eye to the anterior inferior angle of the masseter muscle at the lower border of the lower jaw.. The anterior temporal and facial arteries are useful to the anesthetizor in studying the pul.se, and also to the physician when the patient is sleeping. Expression is due to muscular traction upon the facial integument. In facial hemiplegia, when the muscles of the affected side have lost their power, expres- sion is gone, and the wrinkles of the face disappear. The " expression of the eye " is due to wrinkling of the lids and the peri-ocular integument. The study of the relation between facial expression and the permanent markings of the face resulting therefrom, as an index to character and disposition, is still in its infancy. Note the proximity of the muscle centers of the face in the ascending frontal and parietal gyri to the speech center. The latter is at the tip of the operculum around the ascending arm of the Sylvian fissure, and at the lower part of the ascending gyri. Just above it is the lip center, followed by that of the face, fingers, hand, and arm, with that of the lower limb overtopping all. Is this not also the order in which these muscle groups arc involved during increasing animation accompanying a dis- cussion ? The central excitement becomes greater and extends over wider areas, sending larger and more intense impulses to those muscle bundles which traverse the facial integument and jjuU its surface hither and thither, forming wrinkles, PLATE CXLVII INCISIONS FOR DISSECTION. 597 PLATE CXLVIIL Artery in superficial fascia 1 1\ I Skin Superficial fascia ^ Occipito-frontalis aponeurosis' Areolar tissue Outer table of skull Diploe / Dura mater Inner table of skull LAYERS OF SCALP. ( I CIRSOID ANEURYSM. 599 SCALP. 601 dimples, scowls, and )iuckorinc;s, oxpivssivo of (lu' (■(iii(li(ira-orbital vessels. To divide the nerve well back in the orbit, it is necessary to sever the orbito-tarsal ligament and depress the orbital fat, when the nerve is sepa- rated from its connections and lifted on a blunt hook. The supra-trochlear ner\'e is exposed through an incision carried in a line drawn from the angle of the mouth through and beyond the inner canthus. The nerve will be found at the point of intersection of this line with the upper margin of the orbit The occasional presence of an accessory supra-orbital foramen, giving passage to a division of the supra-orbital nerve, should not be overlooked. Recurrence of pain 612 SURGICAL ANATOMY. immediately after operation is good presumptive evidence of the existence of an accessory foramen. Temporal branch of the orbital nerve. — About an inch above the zj'goma the temporal fascia is pierced by tlic temporal branch of the orbital branch of the superior maxillary nerve, which is distributed to the integument of the temjile and communicates with the temporal branch of the facial nerve. The auriculo-temporal nerve, a branch of the inferior maxillarj' nerve, accompanies the temporal vessels, lying posterior to tlicm. The auriculo-temporal nerve emerges from beneath the upper part of the parotid gland, and divides into two terminal branches — the anterior and posterior temporal. The anterior temporal nerve, the larger, accompanies the anterior temporal artery to the vertex, and communicates with the facial and temporo-malar nerves. The posterior temporal nerve, the smaller, accompanies the posterior temporal artery. Temporal branches of the facial nerve extend upward over the zygoma upon the temple to supply the attrahens and attolens aurem, the orbicularis palpe- brarum, the frontalis, and the corrugator supercilii muscle. They communicate with the temporo-malar, auriculo-temporal, lacrymal, and supra-orbital nerves. The posterior auricular nerve, a branch of the facial, accompanies the posterior auricular artery, and, like the latter, divides into two branches — a posterior and an anterior. The posterior (occipital) supplies the occipitalis muscle ; the anterior (auricular), the auricle and the retrahens and attolens aurem muscles. This nerve is joined by filaments from the auricular branch of the pneumogastric nerve and from the great auricular and small occipital nerves. The small occipital nerve (occipitalis minor), a branch of the anterior division of the second cervical nerve, supplies the scalp behnid the car and over the occiput. It communicates with the great auricular and the great occipital nerve, and with the posterior auricular branch of the facial nerve. It can be seen in the neck running along the posterior border of the sterno-mastoid muscle. The great occipital nerve (occipitalis major), the largest cutaneous nerve of the scalp, accompanies the occipital artery over the occij)ut. It is the internal branch of the posterior division of the second cervical nerve ; pierces the com- plexus and trapezius muscles near their attachment to the occipital bone ; enters the superficial fascia with the occipital artery, and breaks up into a number of large branches which spread over the back of the head, supplying the integument as fiir forward as tlie vertex. It communicates with the small occipital and the first cervical nerve, and receives a branch from the tliird cervical nerve. The Lymphatics of the Scalp follow the same course as the blood-vessels, which is the general rule. Tlie j)osterior, or occi])ital, lymphatics enter the occipital glands situated along the origin of the occipitalis muscle ; the postero- PLATE CLII. Malar br. of facial n Orbital a, Temporal br. of orbital n Supraorbital n. Supraorbital a. /M Transverse facial a. Temporal br.of facial n. Posterior temporal a. Auriculo-temporal n. Supcrfrcal temporal v. Supratrochlear n Frontal a Angular a Occipital a. Superior coronary a Inferior coronary a Inferior labial a Facial a. Facial V. Anterior auricular i Middle temporal a. Parotid gland Supramaxillary br. of facial n. Stenson's duct Buccal br of facial n. infraorbital br.of facial n. Socia parotidis ARTERIES, NERVES, AND MUSCLES OF SCALP AND FACE. 613 SCALP. G15 lateral, or posterior auricular, set enter the posterior auricular glands situated upon the mastoid attachment of the sterno-mastoid muscle ; the temi)oral h-mphatics enter the glands situated upon and within the parotid gland ; and a frontal set end in the facial lymphatics. In congestion of the scalp due to cold, and in otiur alU'ctions of tliis region -wliicli increase the activity of the lynipliatics, these glands are considerably swollen and painful. The occipito-frontalis muscle and ajioneurosis, exposed upon the side from which the superficial foscia has been removed, will now be studied. The occipito-frontalis is a broad, musculo-aponeurotic layer covering one side of the vertex of the skull from the occiput to the l)row. It consists of two flattened muscular bellies, an occipital and a frontal, with an intervening aponeu- rosis. The ornpilnl hclly (occipitalis muscle), thin and quadrangular, arises from the outer two-thirds of the superior curved ridge of the occipital bone and the adjoining mastoid process, thus leaving a triangular interval between tlie two occipitales muscles as their fibers eventually meet higher up in the median line. The fibers are about an inch and a half in length and ascend to the aponeurosis. Blood Supply. — From the occipital and posterior auricular arteries. Nerve Supply. — The occipitalis muscle derives its nerve supply from the posterior auricular branch of the facial and, exceptionally, from the occipitalis minor nerve. The frontal belly (frontalis muscle), a thin, muscular layer having intimate cutaneous connections, arises from the aponeurosis below the coronal suture. It descends over the forehead and blends with the orbicularis palpebrarum, the corru- gator supercilii, and the pj'ramidalis nasi muscle. Blood Supply. — From the frontal, supra-orbital, and anterior temporal arteries. Nerve Supply. — The frontalis muscle derives its nerve supply from the temporal branch of the temporo-facial division of the facial nerve. The aponeurosis extends over the vertex and is continuous across the middle line witli the aponeurosis of the opposite side ; laterally it is continued over the temporal fascia to the zygoma, just above which it is attached to that fascia. Connected with the lateral portion of the aponeurosis are the attolens and attrahens aurem muscles. It is intimately connected with the skin through the attachment of the superficial fascia, and but loosely connected with the pericranium by the connective tissue which intervenes, thus accounting for the movement of the integument when the occipito-frontalis muscle is in action. Action. — Contraction of the anterior belly of the muscle elevates the eye- 61f) SURGICAL ANATOMY. brow and produces wi'inkliug of the forehead ; if contraction be continued, it draws the scalp forward, and pulls up the skin of the nose, to the extent even of moving the naso-labial folds ; contraction of the occipital belly draws the scalp backward ; and alternate contraction of the two bellies moves the scalp backward and forward. Dissection. — Divide the aponeurosis in the median line, and make another incision at its junction with the frontalis muscle. Reflect the aponeurosis outward and backward, and the frontalis muscle downward. Areolar tissue layer.— The mobility of the scalp depends entirely upon the laxity of the subjacent areolar tis.sue layer ; it is this layer which permits ex- tensive flaps of the scalp to be torn loose. When the hairs become caught in moving machinery the entire scalp maj^ be torn off, laying this tissue bare. It was due to the laxity of this layer that the American Indian, with no knowl- edge of anatomy or surgery, was able to peel off the scalp with so much ease. Exposure of the skull in a postmortem examination is effected by peeling off the scalp along this layer of tissue, and it is remarkable with what ease the skull can thus be exposed. To further illustrate the laxity of this tissue, it will suffice to relate a case mentioned by the late D. Hayes Agnew : A midwife attending a woman in child-birth incised the child's scalp, thinking it the protruding bag of waters. Labor pains came on, and the head protruded through the scalp wound with the entire vault of the skull laid bare. Tumors. — By careful examination tumors situated above the occipito-frontalis aponeurosis or in it will be seen to be freely movable. All immovable growths of the scalp should be most carefully examined before extirpation, for they are probably beneath the aponeurosis ; a tumor originating within the cranium may force its way outward and form a prominence on the scalp. Wounds involving only the skin and superficial fascia of the scalp, when the occipito-frontalis muscle or its aponeurosis has not been divided, do not gape, because of the close adherence of the skin to the superficial fascia and of the superficial fascia to the aponeurosis. The areolar tissue layer permits of wide separation of the edges of a wound which divides the occipito-frontalis aponeu- rosis. Antero-posterior wounds which involve the aponeurosis gape but little, while the edges of transverse wounds are widely separated by the contraction of the occipito-fi'ontalis muscle. The great vascularity of the scalp lessens the likeli- hood of sloughing and gangrene. A large flap of the scalp attached by but a small pedicle is much less likely to perish than a flap of skin torn from another part of the body, as the vessels of the scalp run immediately beneath the skin and are included in the flap. In phlegmonous erysipelas and in deep inflam- mation of the scalp the ari'olar tissue layer becomes infiltrated with jnis and conse- quently sloughs. As the vessels are superficial to this layer the skin does not SCI LP. 617 necrose, ulcerate, and allow pointing, and for this reason it is important to incise early. The pericranium (external periosteum) is l)Ut loo.sely attached to tliu hune, except at the sutures, where the union is lirm. In lacerated wounds of the scalp the pericranium is frequently stripped from the skull to the (.'xtent of exposing large areas of bone. The pericranium differs in its iunctions from the peiiusteum covering other bones in that, if the periosteum be removed to any extent hom another bone, the part of the bone from which it is removed will most probably necrose, while the pericranium may be stripped from a considerable part of the vault of the cranium without necrosis following. This is due to the fact tha1> the bones of the skull receive their blood supply chiefly from the vessels of the exter- nal (endosteal) layer of the dura mater, while the other bones are nourished to a great extent through their periosteal covering. The pericranium at the sutures becomes continuous with the external layer of the dura mater, con.stituting the so-called intersutural membrane. It is also continuous with the dura at the for- amina ; hence it is that inflammation of the pericranium may extend by continuity and involve the dura mater, producing pachymeningitis. Collections of blood or pus in the scalp may be situated superficial to the occipito-frontalis aponeurosis, between the aponeurosis and the pericranium or beneath the pericranium. A collection superficial to the aponeurosis is of but little moment, since the density of the superficial fascia causes it to be circum- scrilied. Collections in ■ the areolar tissue layer, between the aponeurosis and the pericranium, are limited only by the attachments of the occipito-frontalis nuisi'lu and its aponeurosis ; thus they may undermine the entire scalp and prove serious if not evacuated early. Collections beneath the pericranium are limited to a single bone, on account of the sutural attachments of the membrane. Collections in the areolar tissue layer call for drainage, and should they be slow in healing, the scalp mu.st be firmly bandaged in order to arrest the movements of the occipito- frontalis muscle. Hematomata in the areolar tissue layer are uncommon, except as a result of fissured fracture of the skull with rupture of one of the branches of the middle meningeal artery, or of the superior longitudinal or lateral sinus, as the areolar tissue between the aponeurosis and the pericranium contains but very few vessels. Collections of blood beneath the pericranium, generally termed cephalhematomata, must be limited to one bone, since the membrane dips into the sutures and becomes continuous with the dura mater ; they are usually congenital and due to pressure upon the head at birth. In septic inflammation of the scalp infection may reach the superior longitudinal sinus through the parietal emi.?sary vein and the lateral sinus through the occipital and posterior auricular veins and their comnu;nications with S-40 618 SURGICAL ANATOMY. the mastoid vein which empties into the lateral sinus. Through the anastomoses between the diploic veins and the veins of the pericranium septic material in the scalp may reacli the sinus alse parvte and the cavernous sinus through the fronto- sphenoid diploic vein, the superior petrosal sinus through the anterior temporal diploic vein, and the lateral sinus through the posterior temporal and occipital diploic veins. In erysipelas, abscess, and other infectious inflammations of the scalp germs may enter the sinuses through these various routes and cause throm- bosis, embolism, and pyemia. Temporal fascia. — The temporal fascia is a white, shining membrane, which is stronger than the occipito-frontalis aponeurosis in this location, and which gives attachment by its under surface to the superficial fibers of the temporal muscle. Above, it is attached to the entire extent of the temporal ridge as a single layer ; while below, it divides into two laj^ers, the outer of which is attached to the external and the inner to the internal border of the upper margin of the zygo- matic arch and zygomatic process of the malar bone. Between these two layers are seen a small quantity of fat, the orbital branch of the middle temporal artery, and the temporal branch of the temporo-raalar or orbital branch of the superior maxillary nerve. In relation with its outer surface is the extension of the occipito- frontalis aponeurosis, the orbicularis palpebrarum, the attolens and attrahens aurem muscles, the temporal vessels, the auriculo-temporal nerve, and the temporal branches of the orbital and facial nerves. Immediately above the zygoma it is pierced by the middle temjjoral artery, a branch of the temporal. Density of the temporal fascia. — Owing to the density of this fascia abscesses beneath it very rarely point upon the surface, the pus passing in the direction of least resistance — namely, through the pterygo-maxillary region into the mouth or neck. Its unyielding nature is well illustrated by a case recorded by Denonvilliers : " A woman who had fallen in the street Avas admitted to the hospital with a deep wound in the temporal region ; a piece of bone several lines in length was found loose at the bottom of the wound and was removed. After its removal the finger could be passed through an opening with an unyielding border, and came in contact with some soft substance beyond. The case was considered one of com- pound fracture of the squamous portion of the temporal bone, with separation of a fragment and exposure of the brain. A bystander, however, noticed that the bone removed was dry and white. A more thorough examination of the wound revealed the fact that the skull was uninjured, that the suppo.sed hole in the skull was merely a laceration of the temporal fascia, that the soft matter beyond was muscle and not brain, and that the fragment removed was simply a piece of bone, which, lying on the ground, had been driven into the soft parts when the woman fell " (Treves). PLATE GLIII. Supraorbital a Supraorbital n Infraorbital br.of facial n. Temporal br. of orbital n. Malar br.of facial n. Auriculo-temporal n. Middle temporal a. Anterior auricular a. Superficial temporal v, Superficial temporal a. Facial n. Posterior auricular a. nternal maxillary a. uccal br.of facial. n. -Inframaxillary br.of facial n. y br.of facial n. I a. Labial br. of infraorbital n) Nasal br. of infraorbital n. TEMPORAL FASCIA AND NERVES OF FACE. 620 PLATE CLIV, iTemporal m. Superficial temporal a. Facial n. ^ Internal maxillary a. Temporo-maxillary v. Masseter m Platysma myoides m. TEMPORAL MUSCLE, 621 PLATE CLV, INCISIONS FOR DISSECTION AND LINES FOR VESSELS AND NERVES. 623 FACE. G2.5 Dissection. — Tlie temporal fascia slinuld now be detached from Che zygomatic arch and reflected upward, whrn (lie greater ])ortion of the temporal muscle and a quantity of fat overlying the muscle above the zygoma will be exposed. The tendon of insertion of the muscle -will be seen in dissecting tiie face. The temporal muscle, broad, flat, and triangular, is situated on the side of the head, and occupies the temporal fossa. It arises from the under surface of the temporal fascia and from the whole of tlie temporal fossa, whence its fibers descend and converge to a tendon which {)asses under the zygomatic arch to be inserted into the apex, the inner surface, and the fore part of the coronoid jirocess of the lower jaw down to tlie last molar tooth. Blood Supply. — From the middle and deep temporal arteries. Nerve Supply. — Derived from the temporal branches of the inferior maxillary nerve. Action. — The action of the temporal muscle is to elevate the lower jaw ; its posterior fibers also assist iii drawing the lower jaw backward after other nmscles have carried it forward. FACE. Dissection. — The dissection of the face should follow that of the scalp. The head should be placed in the same position as for the dissection of the scalp, but slightly lower, and turned so that the side of the face to be dissected is upward. The cheeks and nostrils should be distended with cotton or oakum and the lips sewed together. The muscles and vessels should be dissected on one side of the face and the nerves on the other. The incisions are made as follows : The first incision is made from the nasal eminence along the median line of the nose, around the aperture of the nostril, along the median line of the upper lip, around the mouth along the line where the skin joins tlie mucous membrane to the median line of the lower lij), anil thence to the point of the chin. A second incision is carried along the lower border of the jaw to the angle of the jaw, then upward to the lobe of the ear. Reflect the skin outward. The facial muscles (muscles of expression) are inserted partly into the skin, and great care must be taken that they are not removed with the skin. The skin of the face is remarkably thin, and freely supplied with vessels and nerves. On account of the free blood supply it is a common site of nevi, except over the chin, where it is peculiarly dense and adherent to the parts beneath. The skin covering the eyelids and the bridge of the nose, owing to the presence 626 SURGICAL ANATOMY. of a layer of lax cellular tissue, is loosely adherent to the parts beneath. Over the cartilages of the nose the skin is so intimately adherent to the tissues beneath that it is removed with difficulty. It is very freely supplied with sebaceous and sudor- iferous glands, and hence is commonly the site of acne and eruptions which especially involve the sebaceous follicles ; it is also the site of sebaceous tumors. Facial abscesses usually point quickly and seldom attain large size. The superficial fascia — the cellular tissue layer of the face — contains a con- siderable amount of fat, except in the eyelids and over the bridge of the nose. The laxity of the cellular tissue favors the spreading of infiltrations, so that the cheeks and other parts of the face may become greatly swollen. In general dropsy the face soon becomes puffy, the edema first appearing, as a rule, in the lax areolar tissue of the lower eyelid. The soft tissues of the cheek favor the spread of destructive processes. In cancrum oris — a form of gangrene of the mouth attack- ing the young — the whole cheek may be lost in a few days. Great contraction is apt to follow upon loss of substance, so that the jaw may be firmlj' closed in some cases, as is seen after recovery from deep ulceration (Treves). The mobility of the tissues of the face renders this region favorable for the performance of plastic operations, and their vascularity insures a j^rompt and perfect union. Notwith- standing the fact that there is a large quantity of fat in the subcutaneous tissue, fatty tumors are rarely seen in this region. The thickness of the tissues of the cheeks and lips favors the embedding of foreign substances in these parts. Thus, a tooth which has been knocked out has remained embedded in the lip. Henry Smith reported a remarkable case in which he removed a piece of tobacco-pipe three inches long from the cheek, where it had remained for several j'cars. Dissection. — The superficial fascia — underlying which are the muscles, vessels, and nerves — should be removed in the same manner as the skin, taking care not to disturb the muscles. As the superficial fascia is not easily removed in a continuous layer, it may be taken away in sections, the dissection being made in the line of the muscular fil)ers ; this is necessary, too, in order to avoid dividing the blood-vessels and nerves of the face. Tlio removal of the fascia in this manner exposes the muscles, the vessels, and the nerves. The Muscles of the Face (muscles of expression) are divided into three groups : those of the nose, those of the eyebrows and eyelids, and those of the mouth — ('. e., nasal, palpebral, and oral. The Muscles of the Nose are the pyramidalis nasi, the compressor nasi, the levator labii suporioris alajque nasi, the dilator naris, and the depressor alse nasi. The pyramidalis nasi muscle covers the nasal bone, and is continuous above with the li'ontalis muscle, where it is attached to the deep surface of the inter- superciliary integument. It arises from the aponeurosis over the cartilage of PLATE CLVI, Occipito-frontalis aporeuros.s Attrahons aurem m, AttoHens aurem m. Retrahens aurem m. Occipitalis m. / Parotid gland Deep portion of nnasseter m. Superficial portion of masseter m. Buccinator m. Platysma myoides m. Orbicularis oris m. Depressor labii inferionsm Levator menti m. Posterior dilator narium m Compressor narium m. Anterior dilator narium m. Compressor narium minor m. Zygomaticus major m. ^Zygomaticus minor m. Risorius m. Levator anguii oris m. Levator labii superioiis m. Levator labii superioris alaeque nasi Depressor anguii oris m. MUSCLES OF FACE AND SCALP. 627 FACE. 629 the nose, where it joins the lower edge of the nasal bone and the compressor nasi muscle. Nerve Sitply. — From the iiifru-orbital branch of the temporo-facial division of the facial nerve. Action. — It renders the skin over the cartilages tense, and that over the root of the nose lax, thus forming the transverse crease at the root of the nose. Tiie compressor nasi muscle is triangular in shape, arises bj' its apex from the canine fossa of the supi'rior maxillary bone, and ends in the aponeurosis covering the cartilaginous part of the nose, blending with the corresponding muscle of the opposite side. The origin of this muscle is concealed by the levator labii superioris alajque nasi muscle. Nerve Supply. — From the infra-orbital branch of the upper division of the facial nerve. Action. — It throws the skin at the side of the nose into vertical wrinkles, aids in the elevation of the upper lip, and slighth' compresses the cartilaginous ridge of the nose. When the compressor nasi muscle is reflected from the median line outward, the suiierficial branch (naso-labial) of the nasal nerve, which becomes subcutaneous between the nasal Ijune and the lateral nasal cartilage, will be seen running down- ward to the tip of the nose. The levator labii superioris alaeque nasi muscle, placed by the side of the nose and overlai>pingtlie origin of the compressor nasi muscle, arises from the upper part of the nasal process of the superior maxilla. It descends, and divides into two portions : the inner and smaller ])art is inserted into the inner side of the ala nasi, and the outer into the upper lip, blending with the orbicularis oris muscle. It is partially overlapped near its origin by the orbicularis palpebrarum muscle. Nerve Supply. — From the infra-orbital branch of the facial nerve. Action. — It raises the inner half of the upper lip, and draws outward the wing of the nose, thus dilating the anterior naris. The dilator naris muscle consists of two portions — an anterior and a posterior. The anterior portion is a thin fasciculus which passes from the lower edge of the cartilage of the wing of the nose to the integument over the ala ; the po.sterior portion arises from the margin of the nasal notch of the superior maxilla and from the outer surface of the sesamoid cartilages of the nose, and is inserted into the skin over the back and lower margin of the ala of the nose. Nerve Supply. — From the infra-orbital branch of the facial nerve. Action. — It enlarges the anterior naris by raising and everting its outer edge, thus counteracting its tendency to be closed by atmospheric pressure. In condi- tions occasioning dyspnea — e. g., laryngeal or tracheal obstruction — the action of G30 SURGICAL ANATOMY. those muscles can plainly be seen, and constitutes one of the signs which indicate tracheotomy or intubation. The depressor alae nasi is a short, flat muscle which may be exposed when the upper lip is everted and its mucous membrane removed from the side of the labial frenum. It arises from tlie incisive fossa of the superior maxilla, whence its fibers ascend to be inserted into the septum nasi and the posterior lower jiart of the wing of the nose. Nerve Supply. — From the buccal branch of the cervico-facial division of the facial nerve. Action. — It draws downward and inverts the edge of the nasal cartilages. The Muscles of the Eyelids and Eyebrows are the orbicularis palpebrarum, the corrugator supercilii, the levator palpebrae superioris, and the tensor tarsi. Tendo oculi (tendo palpebrarum). — Before examining the orbicularis palpe- brarum the tendo oculi (internal tarsal ligament) is to be noted. It is a short tendon, about one-sixth of an inch in length by one-twelfth of an inch in breadth, and can readily be felt at the inner angle of the eye after drawing the eyelids outward. It is attached to the nasal process of the sujierior maxilla in front of the lacrymal groove, passes transversely outward in front of the lacrymal sac, and divides into two portions, separated by the caruncula lachrymalis ; the upper portion is attached to the inner extremity of the upper, and the lower to the inner extrem- ity of the lower, tarsal cartilage. As the tendon crosses the lacrymal sac it gives off a strong aponeurotic lamina, which covers the sac and is attached to the margin of the lacrymal groove. This expansion will be seen on reflecting that portion of the orbicularis palpebrarum muscle which covers the lacrymal sac. To jiuncture the lacrymal sac a knife is inserted below the tendo oculi in a direction downward and a little backward, dividing the skin, the orbicularis palpebrarum muscle, and the flbrous expansion derived from the tendo oculi. The angular artery and vein are situated on the inner side of the incision. Tlie external tarsal ligament extends, undivided, transversely inward from the edge of the frontal })rocess of the malar bone to the adjacent outer extremities of the two tarsal cartilages. The orbicularis palpebrarum (orbicularis oculi, sphincter oculi) is a thin, broad muscle which surrounds the margin of the orbit and the eyelids, forming a .sphincter ; it is continuous, above, with the fibers of the frontalis muscle. It arises from the internal angular process of the frontal bone, the nasal process of the superior maxilla, the tendo oculi, and the lower margin of the orbit. From this origin the fibers are directed outward, forming a series of oval curves which cover the eyelids, surround the margin of the orbit, and spread over the forehead, temple, and cheek. The central fibers, occupying the eyelids and connected inter- PLATE CLVII, Pulley Tendon of superior oblique m Superior rectus m Corrugatorsupercilii m. Puncta lachrymalia Meibomian gland Conjunctiva Orbital fat Inferior rectus m Inferior oblique m Tensor tarsi m. TENSOR TARSI AND CORRUGATOR SUPERCILIl MUSCLES. 632 FACE. GoS nally with the tendo oculi ami externally willi tlie external tarsal ligament ami the malar bone, constitute the palpebral porfinn of tlie nniscle. Tlic lihers of this portion, which are in immediate relation witli the eyelashes, have been described as the ciliar}/ mui^cle ; but this, however, must not be confounded with the ciliary muscle proper — the muscle of visual accommodation. More peripheral fibers con- stitute the orbital portion of the muscle. The latter arise from the internal anjjular process of the frontal bone and from the nasal pi'ocess of the superior maxillary bone, and are distributed around the margin of the orl)it. They are continuous above with the frontalis and corrugator supercilii muscles, and extend outward upon the cheek to mingle with the elevators of the upper lip and nose and with the zygomaticus minor muscle. Nerve Supply. — From the temporal and malar branches of the temporo-facial division of the facial nerve ; hence in paralysis of this nerve the eyelids on the paralyzed side can not be closed. Action. — The orbicularis palpebrarum muscle closes the eyelids and protects the eye. The palpebral portion of the muscle contracts during winking. Con- traction of the orbital portion presses the eyeball backward into the orbit and draws the soft parts covering the margin of the orbit around the eyeball, thus protecting it from injury. While tliis cushion of tissue may be severely bruised, as is seen in a "black" eye, the eyeball itself is rarely injured. As the outer portion of the orbicularis is mingled with the fibers of the frontalis muscle and the elevators of the upper lip and nose, slight depression of the eyebrow and elevation of the upper lip and of the wing of the nose follow contraction of this portion. Strong contraction of the entire muscle holds the eye firmly in the orbit, thus protecting it against the severe strain in violent coughing, sneezing, and vomiting, during which acts the muscle usually contracts spasmodically. Contraction of the palpebral portion of the muscle following that of the orbicular portion tends to draw the lids slightlj' inward, thus directing the tears to the inner angle of the fissure between the eyelids, near which are situated the puncta lachry- malia. The tensor tarsi (Horner's muscle) is a small muscle, really a deep portion of the orbicularis palpebrarum, situated at the inner angle of the orbit behind the tendo oculi. To expose it it is necessary to cut perpendicularly through the middle of the upper and lower eyelids, when the nasal half of each lid should Ije reflected inward and the mucous membrane removed. The muscle will tie seen to arise from the ridge on the lacrymal bone. It passes outward behind the lacrymal sac and divides into two portions which cover the posterior aspect of the canaliculi. The two portions terminate in the inner ends of the uppjer and lower tarsal cartilages near the puncta lachrj'malia. 634 SURGICAL ANATOMY. Nerve Supply. — From the infra-orbital branch of the temporo-facial division of the facial nerve. Action. — It compresses the lacrymal sac. i, The corrugator supercilii muscle arises from the inner end of the superciliary ridge of the frontal bone. Its fillers are directed outward and a little upward to the under surface of the orljicularis palpeljrarum and frontalis muscles, to be inserted into the former over the middle of the supra-orbital arch. Nerve Supply. — From the temporal branch of the temporo-facial division of the facial nerve. Action. — It draws the ej^ebrow downward and inward, thus making the vertical wrinkle of the forehead at the inner extremity of the eyebrow. Dissection. — The nasal half of the orbicularis palpebrarum and a small jtart of the frontalis muscle having been reflected inward, the corrugator supercilii is exposed. The levator palpebrae superioris muscle. — By reflecting the outer as well as the nasal half of the orbicularis palpebrarum muscle, and detaching the orbito- tarsal ligament from the superior orbital margin and reflecting the ligament downward, tlie insertion of the levator palpebrse superioris muscle by a broad aponeurosis into the upper border of the tarsal cartilage of the upper eyelid can be seen. The Muscles of the Mouth are the orbicularis oris, the levator labii supe- rioris, the levator anguli oris, the zygomaticus major, the zygomaticus minor, the buccinator, the risorius, the depressor labii inferioris, the depressor anguli oris, and the levator laliii inferioris. The risorius muscle (Santorini's muscle), a part of the platysma myoides, consists of a thin bundle of fibers which arises from the fascia covering the masseter muscle and parotid gland, and passes horizontallj' forward to the angle of the mouth, where it joins the fibers of the orbicularis oris and depressor anguli oris muscles ; some of its fibers pass to the skin at the angle of the mouth. Nerve Supply. — From the buccal brancli of the lower division of the facial nerve, which enters it from beneath. Action. — It retracts the corner of the mouth. Its contraction during certain conditions, as in tetanus, causes the " risus sardonicus" of the old authors. The orbicularis oris muscle (sphincter oris), nearly an inch in breadth, sur- rounds the mouth, forming a sphincter; at its periphery it unites with several muscles which act upon that aperture. It consists of two parts — an inner, central, or labial part, and an outer, peripheral, or facial i)art ; the two differing in appear- ance and in the arrangement of fibers, like the orbicularis palpebrarum muscle. Tlie inner, central, or labial portion consists of pale, thin fibers, fine in texture, FACE. 635 corresponds in position witli tlic red margin of the lips, and has no bony attach- ment, but is continuous around tlie angles of the mouth from oni- lip to the other. The outer, peripheral, or facial part is thinner and wider than the labial, and has a bony attaclinient as well as connection with the adjacent muscles. In the upper lip the orbicularis oris muscle is attached at each .side of the middle line to the lower part of the septum nasi by naso-labial slips, and to the alveolar border of the upper jaw opposite the incisor teeth ; in tlir lower lij) it is attached to the alveolar border of the lower jaw opposite the canine teeth by a single fasciculus (musculi incisivi). The cutaneous surface of the nuiscle is intimately connected with the skin of the lips and surrounding parts. The intimacy of this union is so great in some instances that the mouth is surrounded bj' radiating wrinkles, especially marked in the upper lips of women. The labial integument of the male probably contains fewer \\rinkles on account of the presence of large hair-bulbs. The deep surface of the orbicularis oris is covered by mucous membrane, between which and the muscle, in the .submucous ti.ssue, are the coronary arteries and the labial glands. Nerve Supply. — From the buccal and supra-maxillary branches of the cervico-facial division of the facial nerve. Action. — "When the facial and labial portions act conjointly, they press together and project the lips. Tlie labial fibers acting alone bring the lips and the angles of the mouth together and invert the lips. The facial fibers acting alone press the lips against the alveolar borders of the jaws, and, at the same time, evert the lips. The orbicularis oris is the antagonist of all those muscles which converge to the lips from the various parts of the face. Hypertrophy of the orbicularis oris or, rather, an increase of the connective tissue, particularly of the portion in the upper lip, to the extent of producing a considerable deformity, is sometimes seen, and indicates a plastic operation involving the removal of a trans- verse, wedge-shaped section from the lip. The levator labii superioris muscle (levator labii proprius) arises from the superior maxilla above the infra-orbital foramen, and is inserted into the upper lip, its fibers blending with the orbicularis oris muscle. At its origin it is over- lapped b}' the orbicularis palpebrarum, and covers the infra-orbital vessels and nerves. It is a landmark in exposing the infra-orbital nerve. Nerve Supply. — From the infra-orbital branch of the upper division of the facial nerve. Action. — It raises the upper lip, at the same time making prominent the skin below the eye. Dissection. — The levator labii superioris muscle is to be reflected downward from its origin, when will be exposed the levator anguli oris, the infra-orbital plexus of nerves, and the infra-orbital vessels. 636 SURGICAL ANATOMY. Tlie levator anguli oris muscle (musculus caninus) arises from the canine fossa of the superior maxilla below the infra-orbital foramen, and is inserted into the angle of the mouth, superficial to the buccinator muscle, its fibers blending with the orbicularis oris, the zygomatici, and tlie depressor anguli oris muscle. Nerve Supply. — From the infra-orbital branch of the upper division of the facial nerve. Action. — It raises and draws inward the angle of the mouth. The depressor labii inferioris muscle (quadratus menti) arises from the oblique line of the lower jaw by a wide origin, extending from a point below the foramen mentale nearly to the symphysis. Its fibers are associated with those of the muscle of the opposite side, ascend, and are inserted into the integu- ment of the lower lip, blending with the orbicularis oris. Its outer border is overlapped by the depressor anguli oris muscle. Nerve Supply. — From the supra-maxillary branch of the cervico-facial divi- sion of the facial nerve. Action. — It depresses and everts the lip. The depressor anguli oris muscle, triangular in shape, hence also called triangularis oris, arises from the oblique line of the lower jaw external to the depressor labii inferioris muscles. Its fibers ascend, to be inserted into the angle of the mouth, intermingling with the zygomatici, the levator anguli oris, the risorius, and the orbicularis oris muscle. Its outer border overlaps the anterior jaart of the buccinator muscle. Nerve Supply. — From the supra-maxillary branch of the cervico-facial divi- sion of the facial nerve. Action. — It draws the angle of the mouth downward and outward, producing an expression of sorrow. The levator labii inferioris, or levator menti, is a small muscle seen by everting the lip and dissecting off the mucous membrane on each side of the laljial frenum. It arises from the fossa below the incisor teeth, near the .symj)hysis. Its fibers descend, and are inserted into tlie integument of the chin. Nerve Supply. — From the supra-maxillary branch of the cervico-facial divi- sion of the facial nerve. Action. — It assists in raising the lower lip, at the same time wrinkling the integument of the chin over the point of its insertion. Tlic zygomatic muscles jiass olili(|U(ly from the zygomatic arch to the upper liji and angle of the mouth. The zygomaticus major arises from the outer part of the malar l)one in front of the suture, between it and the zygoma ; its fibers pass (iliii(|uely downward and inward, to be inserted into the angle of the month, blending with the fibers of the orbicularis and depressor anguli oris muscles. FACE. 637 The zygomaticus minor arises from the (lutcr jiart of llic malar l)Oiic, anterior to the zygomaticus major, and Ix'hiiid the suture between the malar bone and Ihe superior maxilla ; its tihers pass downward and inward, to be inserted into the lower border of the levator labii superioris muscle. It is often absent. Nervk Supply. — From the infra-orbital branch of the temporo-facial divi- sion of the facial nerve. Action. — The zygomaticus major draws the corner of the month upward and backward ; the zygomaticus minor assists the levator laljii superioris nmscle in raising the upper lip. Bucco-pharyngeal fascia. — Before making a dissection of the buccinator muscle, the thin layer of fascia which covers and adheres closely to its surface should be studied ; it is attached to the alveolar borders of the superior and infe- rior maxillary bones, and posteriorly, where it is thickest, is continuous with the fascia over the constrictors of the pharynx. It is called by Holden the "bucco- pharyngeal fascia," since it supj^orts and strengthens the walls of the pharynx and mouth. The density of the buccal fascia offers a barrier to the escape of pus into the mouth or pharynx from an abscess in the cheek. The buccinator, quadrangular in form, is a thin, flat muscle which occupies the interval between the jaws at the side of the fiice. It arises from the outer surface of the alveolar borders opposite the middle and jjosterior molar teeth of the superior and inferior maxilla?, and Ijehind from the pterygo-maxillary ligament. The ptcrygo-maxillari/ ligament is a fibrous band extending from the apex (hamular process) of the internal pterygoid plate of the pterygoid process to the posterior extremity of the internal oblique line (inylodiyoid ridge) of the lower jaw ; it separates the buccinator muscle from the superior constrictor of the jiharynx. The fibers of the buccinator pass forward, to be inserted into the orbicularis oris muscle at the angle of the mouth. The central fibers intersect one another, M'hile the upper fibers pa.ss to the upper lip and the lower fibers to the lower lip. In relation with the superficial surface of the buccinator muscle is a large mass of fat (buccal pad), which separates it from tlie ramus of the lower jaw, the masseter muscle, a small portion of the temporal muscle, and the muscles converging to the angle of the mouth. Aljsorption of the fat overlying the muscle is followed by sinking of the cheek, as seen in per.sons who are emaciated. In compression of the brain the flapping of the cheeks in breatliing is the result of paraly.sis of the nerve supplying the buccinator, while the stertorous breathing (snoring) is the result of paralysis of the nerves of the soft palate. Tlie duct of the parotid gland (Stenson's duct), which pierces the Imccinator muscle opposite the second molar tooth of the superior maxilla, crosses the upper part of the muscle obliciuely, at about a finger's breadth below the zygoma. It is also crossed by the facial artery and vein and 638 SURGICAL ANATOMY. by branches of the facial nerve. Internally it is lined by the mucous membrane of the mouth ; between this and the muscle lie a number of racemose glands called the buccal glands. A few of these glands are found on the outer surface of the muscle and are called molar glands. Nerve Supply. — From the facial nerve. The long buccal nerve, a branch of the inferior maxillary, pierces the buccinator muscle on its way to supply the mucous membrane of the mouth. Action. — The two buccinator muscles widen the aperture of the mouth transversely and contract and compress the cheeks so that during mastication the food will not remain between the cheeks and the teeth. AVhen but one mu.scle acts, the angle of the mouth is drawn to that side, and the cheek is -wrinkled ; when Avhistling, the muscle contracts and prevents bulging of the cheeks. It is hardly ftiir to the earnest dissector to leave this subject without the consoling reminder that the most expert dissectors can not bring out these muscles in the cadaver as they are shown in the anatomic plates. It must be remembered that some of the facial muscles belong to the panniculus carnosus group, so exten- sive in animals but so limited in man. In some faces the mu.sculature is a com- plex network of subcutaneous fibers running in all directions. In a muscular subject a large number of distinct fasciculi are seen crossing one another, and more or less merged with the constant muscles of the face. This difference in the amount of facial musculature undoubtedly accounts for much of the variation in the amount of facial wrinkling observed in different persons. It is safe to my that a dissection of the muscles of the face with their boundaries as well defined as shown in pictures does more credit to the dissector's skill in imitating a diagram than to any painstaking effort to exhibit the natural state of the parts. The Facial Artery, a branch of the external carotid, enters the face over the body of the lower jaw, at the anterior inferior angle of the masseter muscle, where its pulsation may readily be felt and it maj' be compressed against the bone. Thence it ascends forward across the cheek, over the buccinator muscle, and beneath the platysma myoides muscle, to the angle of the mouth ; thence to the side of the nose, to terminate at the inner canthus of the eye as the angular artery. Where the artery passes over the lower jaw it is covered by the platy.sma myoides muscle and the deep fascia ; near the mouth it passes beneath tlie zygomatici major and minor and the risorius muscle ; and along the side of the no.se it is usually covered by the levatur ]al)ii superioris aheque nasi. It rests successively on the lower jaw, the buccinator, and the levator anguli oris muscle. The companion ves.sel of the facial arter}', {\\q facial vein, runs in an almo.st .straight line from the inner canthus of the eye to the anterior inferior angle of the masseter muscle, being in contact PLATE CLVlll, Supraorbital a Frontal a. Orbital a. Anterior temporal a. Posterior temporal a. Angular a. Facial a. Inferior labial a. nferior coronary a. Superior coronary a. Occipital a. Posterior auricular a. Superficial temporal a. Anterior auricular a. Middle temporal a. parotid gland Transverse facial a. Stenson's duct ARTERIES OF SCALP AND FACE, G40 PLATE CLIX, Malar br. of facial n. Transverse facial a Orbital a Temporal br. of orbital n. Supraorbital n. Supraorbital a. Supratrochlear n. Frontal a Angular a. Temporal br.of facial n. Anterior temporal a. Superficial temporal a. Posterior temporal a. Auriculo-temporal n. / Superfical temporal \ Occipital a. / Great occipital n. Small occipital n. Posterior auricular a. Infratrochlear n. Artery of septum Lateral nasal a. Superior coronary a, Inferior coronary a Inferior labial a, Facial a Facral Anterior auricular a. Middle temporal a. Parotid gland Supramaxillary br. of facial n. Stenson's duct Buccal br.of facial n. Infraorbital br.of facial n. Socia parolidis ARTERIES, NERVES, AND MUSCLES OF SCALP AND FACE. 641 FACE. 643 with the facial artery at tliesc points, luit eiscwlicrc above and external to it. The artery is crossed by filaments of the facial nerve, while the levator laliii superioris niiisele separates it from the infra-orbital nerve behind. Branches of the Facial Portion of the Facial Artery. — These are the mus- cular, inferior labial, inferior coronary, superior coronary, lateralis nasi, and angular. The muscular branches are directed outward to supply the buccinator, masseter, and internal ptervi^oid muscles. They anastomose with t!u! masseteric and buccal branches of the internal maxillary and with the infra-orbital and transverse tixcial arteries. The inferior labial artery passes inward beneath the depressor anguli oris to supply the nuiscles and integument of the lower lip and chin. It anastomoses with the inferior coronary, the submental branch of the facial, and the mental branch of the inferior dental artery. The inferior coronary artery arises, either independently or in common with the inferior labial, from the facial artery near the angle of the mouth. It passes forward and inward in a tortuous manner beneath the depressor anguli oris toward the angle of the mouth, then pierces the orbicularis oris, and continues between it and the mucous membrane along the free margin of the lower lip. It anas- tomoses with the inferior coronary artery of the opposite side, the inferior labial, and the mental branch of the inferior dental artery. The superior coronary artery, which is larger and takes a more tortuous course than the inferior coronary, arises from the facial artery beneath the 7.ygo- maticus major muscle. It pierces the orbicularis oris, and runs between it and the mucous membrane along the free margin of the upper lip to anastomose with the artery of the opposite side. By the anastomosis of the superior and inferior coronary arteries with their fellows an arterial circle is formed, which surrounds the mouth and can be felt pulsating on the internal surface of the lips between one-fourth and one-half of an inch from the junction of the skin and the mucous membrane. A small branch to the ala nasi and numerous branches to the labial glands are given off from this circle. The artery of the septum of the nose is a liranch of the superior coronary. The tAvigs of this arteria septum narium are a common source of epistaxis (nose- bleed). The hemorrhage from the branches of this vessel is readily controlled by compression of the artery of the septum, either by direct backward pressure against the upper lip, or 1)y pressure from within outward, as when a firm pledget of cotton, paper, or other substance is pushed well up under the lip so as to put its tissues upon the stretch and occlude the lumen of the artery. This is a common procedure practised by the laity. Another simple method is that of holding the cartilaginous end of the nose between the thumb and finger. 644 SURGICAL ANATOMY. Harelip. — In the operation for liarelip the bleeding can be controlled by grasping the lip between the thumb and forefinger. In introducing the harelip pin or suture, it must be passed deep enough to go Ijeneath the divided coronary arterj^. Harelip is a congenital deformity consisting of one or more fissures in the upper lip, the result of arrested development. It may l)e single or double, the fissure or fi.ssures being to the side of the median line of the lip, corresponding to the line of union between the intermaxillary and the superior maxillary bone. In double harelip the intermaxillary bone is often displaced forward. Double harelip is frequently associated with cleft palate. The lateralis nasi artery ari.ses from the focial artery opposite the wing of the nose, and passes forward over the lower part of tlie nose and over the ala ; it supplies the side and dorsum of tlie nose, and anastomoses witli the lateralis nasi artery of the opposite side, the nasal brancli of the ojdithalmie, the infra-orbital, and the artery of the septum. The angular artery, the terminal part of the facial, passes to the inner canthus of the eye, where it lies on the nasal side of the lacrymal .sac and tendo oculi ; it anastomoses with the nasal branch of the ophthalmic and with the infra- orbital artery, and supplies branches to the cheek. In opening an abscess of the lacrymal sac it is important to bear in mind the situation of this arterj' on the inner side of the sac. Nervi molles. — The focial artery and its liranches are surrounded l)y a minute plexus of sympathetic fibers (nervi molles) not demonstrable macroscopi- cally. These fibers are liranches of the superior cervical ganglion of the sympa- thetic, and supply the walls of the artery and its l.)ranches ; they furnish the sympathetic root to the sul)maxillary ganglion. Transverse facial artery. — I'assing transversely acro.ss the face between the zygoma and the duet of the parotid gland, and resting upon the masseter muscle, is the transverse facial artery, which arises from the temporal artery in the substance of the parotid gland. It sup]ilies the small, often detached, part of the parotid gland (the socia parotidis) in relation with the duct, the ma.s.seter and orbicularis palpebrarum muscles, and the integument. It anastomoses with the infra-orbital, facial, and masseteric arteries. It is acc()m])anied liy tAvo or three liranches of the facial nerve. It is (|uite small except wlien it supplies those parts wiiich usually recei\-(' blood from tlie facial artery. It occasionally gives ot^' the coronary and nasal arteries, the facial itself jjeing small. It arises, at times, from the external carcitid artery. 'i'lie facial vein, tlie eontinuatiim nf tlie angular vein, and formed by the union of the frontal and supra-orbital viins, eunnuenees at the inner canthus of the eye and, PLATE CLX, Supraorbital Frontal veins Transverse facial Orbital V. Middio tonnporal v. / Superficial temporal v. |Connmunication with mastoid v. Occipital V. Deep cervical v. lerior division of temporo-maxilldry v. nterior division of temporo-maxillary v. External jugular v. Posterior jugular v. VEINS OF SCALP, FACE, AND NECK, 645 FACE. 647 as already statcil, runs in an almost straialpebral muscles of Miiller. Blood Supply.— The eyelids receive their blood supj.ly from the palpebral and lacrymal branches of the ophthalmic artery and from small branches of the temporal and transverse facial arteries. The palpebral branches of the ophthalmic, two in number, arise from tliat artery near the pulley of the superior oblique muscle ; one is found in each lid and runs through the fibrous tissue layer of the lids between the orbicularis palpebrarum mu.scle and the tar.sal cartilages near their margins. The lacrymal is the first branch of the ophthalmic artery. It accompanies the lacrymal nerve and gives off palpebral twigs which anastomose with the other palpebral arteries to form the tarsal arches. The veins of the eyelids are larger than the arteries, and outnumber them. They empty into the frontal and angular A^eins at the inner canthus, and into the orbital vein at the outer canthus. Some of the veins of the lids pass between and through tlie l)undles of fibers of the orbicularis palpebrarum, and hence in many inflammatory conditions of the conjunctiva and cornea in children, in wliich prolonged spasm of this muscle occurs, the lids arc very apt to become edematous, from interference with the venous flow (Fucho). Nerve Supply.— The nerve supply is free. The nerves to the palpebral portion of tlie orbicularis palpebrarum nuiscle arise from the facia! nerve and enter the lids near the outer canthus. The cutaneous filaments of the ujijier lid are obtained from the lacrymal, supra-orbital, and supra-trochlear nerve, and the lower lid derives its supply from the infra-orbital and infra-trochlear nerves. The non-striated mu.scular tissue of the lids is sujjplied by the .sympathetic nerve. The lymphatics of the eyelids pass to the parotid and submaxillary lymph glands. The conjunctiva has been described. The levator palpebrae superioris muscle arises from the under surface of the lesser \\ing of the sphenoid bone above the optic foramen ; its fibers terminate 65G SURGICAL ANATOMY. in a broad, thin aponeurosis which is inserted into the upper border of the superior tarsal cartilage. This muscle runs above the superior rectus, and its upj^er surface is in relation with the frontal nerve and the supra-orbital artery. The parotid gland, the largest of the salivary glands, weighs from one-half to one ounce. It is situated on the side of the face, and extends as high as the zygoma and below the level of the angle of the lower jaw. It covers about one- third of the masseter muscle, and extends backward to the external auditory meatus, the mastoid process, and the sterno-mastoid muscle. It is lodged in the space between the ramus of the lower jaw and the mastoid process. This space — known also as the bed of the parotid gland — can be increased in size by extending, and diminished by flexing, the head. With tlie mouth wide open — in Avhich posi- tion the angle of the jaw is carried backward and the condyle forward — the width of the space is diminished below, but increased above. The size of the space is influenced by the age of the individual. In the infant, owing to the obliquity of the ramus and the absence of the angle of the lower jaw, it is broader, in propor- tion, below. In advanced age, when the teeth have fallen out, thus allowing the angle of the lower jaw to project forward, the space is broader below. When operating in this space these facts should be kept in mind, as it may be necessary to take advantage of them. The gland has three large processes or lobes : one, the glenoid lobe, extends upward into the posterior part of the glenoid cavity of the temporal bone which it occupies ; another, the pterygoid lobe, extends forward beneath the ramus of the lower jaw, between the external and internal pterygoid muscles ; the third process, the carotid lobe, passes behind the styloid process and beneath the mastoid process and the sterno-mastoid muscle, coming in contact with the internal jugular vein and the internal carotid artery. From the relation wliich the carotid lobe holds to the internal jugular vein, it follows that swelling of the gland, as in mumps, may cause passive congestion of the brain by compression of tliat vein. Tlie anterior margin of the parotid gland overlaps the masseter muscle, and a detached j)ortion of the gland (soda parotidis) lies over that muscle in relation with the upper border of Stenson's duct. From the position which the parotid gland holds with reference to the temporo- maxillary articulation it follows that, in inflammation of the gland, movement of the arlieulation is attended by l>ain ; tlie extent to which the lower jaw can be depressed under these circumstances is dependent upon the amount of swelling. Parotid fascia. — Tlie parotid gland is covered by a dense and strong layer of fascia — a prolongation of the sujierficial layer of the deep cervical fascia, and called the parotid fascia. It is attached above to the zygoma, and is continuous in front with the fascia (■o^•ering the masseter muscle. From the parotid fascia nunicidus processes are sent into the substance of the gland to support its lobules. FACE. 657 The deep fascia of the neck also sends beneath the gland a process continuous witli the stylo-maxillary ligament, which separates the parotid from the submaxillary gland. The fibrous envelop of the parotid gland is incomplete above and in front, where its cavity is in communication with the pterygo-maxillary region. In parotid abscess the pus may, on account of this gap in the fascial envelop, extend into the pterygo-maxillary region, and by way of the latter into the tem- poral fossa, or to the side of tlie pharynx, meeting with less resistance in taking either of these directions than in attempting to reach the surface. The ab.scess may, however, extend into the neck by ulcerating through the layer of fascia beneath the gland. ]\Iany cases of retro-pharyngeal abscess are attended by swelling in the parotid region. Retro-pharyngeal growths — as, for example, sarcomata, when they have attained any size — cause bulging of the inirotid region ; and, conversely, tumors of the parotid may bulge into the pharynx. The severe pain in a rapidly growing tumor or abscess of the gland is due to the density of the fascia covering it. This, too, makes it difficult to detect fluctuation early. It also explains why the pus in a parotid abscess is so slow to find its way to the surface, and wliy an early opening should be made. The intimate relation existing between the parotid gland, the external auditory meatus, and the temporo-maxillarjf articulation is to be borne in mind, as a parotid abscess may open into the meatus or cause involvement of the joint. Purulent meningitis and thrombosis of the cranial sinuses may be caused when pus finds its way through the foramina at the base of the skull. The sensory nerves supplying the parotid gland are the auriculo-temporal branch of the inferior maxillary nerve, the great auricular branch of the cervical plexus, the facial nerve, and branches from the carotid plexus of the sympathetic nerve. In painful affections of the gland the pain is apt to be referred to the areas of distribution of these nerves. The parotid lymphatic glands. — Lj'ing upon the surface of the parotid gland (in front of the cartilage of the ear, and close to the root of the zygoma) are one or more superficial lymphatic glands, enlargement of whicli must not be mistaken for a similar condition of tlie parotid gland itself Contents of the parotid gland. — The parotid gland is important, not only on account of its function, of the position which it occupies, and of the relation it bears to tlie surrounding parts, but also because important structures are found in it. These structures are, from without inward : The facial nerve, passing from behind forward ; the temi-oro-maxillary, superficial temporal, internal maxillary, and posterior auricular veins ; the commencement of the external jugular vein ; the external carotid artery which supplies branches to the gland and divides at the neck of the lower jaw into its two terminal branches — the temporal and internal 658 SURGICAL ANATOMY. maxillary arteries ; the terminal part of the great auricular nerve ; and one or two lymphatic glands. The posterior auricular branch of the external carotid artery and the transverse facial branch of the temporal artery arise in the substance of the gland. The parotid gland is separated from the internal carotid artery, from the internal jugular vein, and from the pneumogastric, glosso-pharyngeal, and hypo- glossal nerves by a thin layer of fascia ; therefore in stab wounds of the parotid region involving one of the two carotid arteries it may be difficult, at first, to tell which of the two vessels has been wounded. From an anatomic point of view it is difficult to see how complete removal of the parotid gland is possible, yet the operation has been done so many times by skilful surgeons that there is no question of its feasibility. Doubtless, as long ago suggested by Fiihrer, Avhen the gland becomes the site of a neoplasm it becomes more compact, its processes being rounded off, as it were, and lifted away from the surrounding structures. Complete removal of the parotid gland results in paralysis of the muscles of expression, for it is impossible to avoid dividing the facial nerve. The author has seen a growth of the overlying lymphatic gland cause facial paralysis from pressure, and thus so closely simulate a parotid neoplasm as to be pronounced a tumor of the parotid gland ; but upon the removal of the growth the parotid gland was seen to occupy the bottom of the wound, and to be in a very much atrophied condition. Socia parotidis. — Tliat portion of the parotid gland resting upon the masseter muscle above the parotid duct (Stenson's duct), and quite separate from the gland proper, is known as the socia parotidis. Its duct empties into Stenson's duct. Stenson's duct. — Running about one finger's breadth below the zygoma, or in a line drawn from the lower margin of the concha to a point midway between the free margin of the upper lip and the ala of the nose, is the duct of the parotid (Stenson's duct). It is about two inches in length by one-eighth of an inch in diameter, being narrowest at its point of communication with the mouth. It lies between the transverse facial artery above and the buccal branch of the facial nerve below. The duct runs over the masseter muscle, turning abruptly inward at its anterior border, passes through the mass of fat overlying the buccinator muscle ami l)rnoatli the facial vein, and pierces the buccinator muscle to open into llie moutli opimsito tlic crown of the second molar tooth of the upper jaw. 1'lie turn of tlie duct around tlie anterior border of the masseter muscle must be borne in mind when passing a probe into the duct from the mouth. In opening a parotid abscess the incision should be horizontal, and should be made below the line of the duct and in front of the posterior border of the ramus of the lower jaw. Failure to observe this caution may result in section of the duct, w'ith FACE. 659 resulting fii^tula (salivary fistula). It is also advisable to take every precaution against cutting througli the gland tissue in opening a parotid abscess, for these collections of pus, like those of the niammtc, generally atl'ect the connective tissue of the gland and not its substance or parenchyma. Stenson's duct may be divided into a masseteric and a buccal portion. The masseteric portion rests upon the niasseter muscle and the /jucca I part extends from the anterior border of the masseter muscle to the termination of the duct in the mucous membrane of the cheek. Fistuke of the masseteric part are closed with difficulty, whereas fistula; of the buccal portion are remedied by making an opening from the duct into the mouth on the j^roximal side of the fistula. The author has successfully treated fistula^ of the buccal portion by exposing the duct through an incision in the cheek, dividing the dvict at the proximal side of the fistula, freeing the duct from the surrounding tissues, and stitching the divided end to the margins of an opening made in the mucous memlsrane of the mouth. Dissection. — Before turning over the head to make the dissection of the oppo- site side of the face, the parotid gland should be removed entire ; this operation will convey an approximate idea of the difficulties which would attend the removal of the gland in the living subject. The masseter muscle should then be exposed and the external ear dissected. In exposing the parotid gland, its fascial covering is seen to be continuous anteriorly with the fascia covering the masseter muscle, and, therefore, the parotid and masseteric fascice are practically one. These fasciae are derived from the superficial layer of the deep cervical fascia, which is continued upward over the body of the lower jaw and attached above to the zygoma. By displacing the parotid gland forward and removing the foscia covering that portion of the masseter muscle in advance of the gland, the muscle itself is exposed. The masseter, the most superficial of the muscles of mastication, is of quad- rate form, and arises as two portion.? — a large, tendinous, superficial layer, and a small, fleshy, deep layer. The superficial sheet arises from the anterior two-thirds of the lower border of the zygomatic arch and from tlie lower border of the malar bone ; its fibers pass downward and l)ackward to be inserted into the outer surface of the angle and lower portion of the ramus of the lower jaw. The deep sheet arises from the posterior third of the lower border and all of the inner surface of the zygoma ; it passes downward and forward to be inserted into the upper half of the ramus and the outer surface of the coronoid process of the lower jaw. The posterior portion of the muscle is concealed by the parotid gland. In relation with the superficial surface of the muscle are the orbicularis palpebrarum, the zj'gomatici major and minor, and the platysma myoides muscle, the anterior margin of the parotid gland, Stenson's duct, the tran.sverse facial vessels, branches of the facial nerve, and, at its anterior inferior angle, the facial vein. In relation 660 SURGICAL ANATOMY. with its deep surface are the buccal pad of fat, the buccinator and a small part of the temporal muscle, the masseteric artery and nerve, and the ramus of the jaw. Blood Supply. — From the masseteric branch of the internal maxillary, the transverse facial, and the facial artery. Nerve Supply. — From the masseteric nerve, a branch of the inferior maxil- lary division of the trifacial nerve. Action. — It raises the lower jaw, as in mastication. The External Ear consists of the pinna, or auricle, and of the tube leading to the tympanic membrane — the external auditory canal. The pinna collects the vibrations of sound, and the canal conveys them to the tj-mpanum. The pinna, or auricle, is pyriform in shape, with its concave surface directed outward and sliglitly forward, and consists of a layer of yellow fibro-cartilage having an uneven surface covered with integument. It is attached to the com- mencement of the external auditory meatus, and consists of various elevations and depressions, each elevation having a corresponding depression on its opposite surface. The deep hollow in its center, which is wide above and narrow below, is called the concha. The concha leads to the commencement of the external audi- tory meatus, and is partly di\ided into two by the beginning of the helix. The helix passes upward, forms the rim of the pinna, and terminates behind in the lobule, which is the lowest portion of the auricle and consists of fatty and areolar tissue. Internal to the helix is the depression called the fossa of the helix, or scaphoid fossa. Internal to the fossa of the helix is the ridge bounding the concha behind and above. This ridge is called the anthelix ; it begins above the lobule, at a small prominence, the antitragus, and bifurcates at the upper part of the auricle, emijracing a small triangular dej^ression — the fossa of the anthelix. In front of the concha and projecting backward over the orifice of the external audi- tory meatus is the tragus. Between the tragus and antitragus is a notch — the incisura intertragica. Dissection. — The integument should be removed from the pinna, when the small and rudimentary muscles and the cartilage will be exposed. The integument of the pinna is thin and delicate. It contains sebaceous glands which are largest in the conclia, and here the ducts of the glands often become filled with foreign matter, giving rise to the so-called comedones. Upon the posterior aspect of the auricle the integument is less firmly attached to the underlying parts than el.scwhere, consequently inflammatory swellings, as in erysipelas, are most marked in this situation. Extravasations of blood beneath the skin are not uncommonly seen as the result of l)lows u|iun tin/ car; tliese so-called othematomata have been most often observed in in.sane persons and in prize-fighters. According to "N'irchow and PLATE CLXII Hulix Fossa of helix Darwin's tubercle Antihelix Concha Antitragus Lobule Fossa of antihelix Tragus ncisura intertragica PINNA. 661 PLATE CI,XIV. Helix Darwin's tubercle Helicis major m. Obliquus auris m. Transversus auris m. Fissure of Santorini Antitragicus m. Processus caudatus INTRINSIC MUSCLES OF PINNA. 663 FACE. 665 Luihviix Meyor, degenerative changes in the hlood-vessels and cartilage favor the occurrence of such extravasations. Cicatricial contractions may cause deftnniity of the pinna after the absorption or evacuation of such hematomata. Under the integument of the lobule gouty deposits (tophi) are sometimes found. The Muscles wliich move the cartilage of the ear as a whole, three in number, have been described under the dissection of the scalp. Tlie muscles proper of the auricle, whiih extend from one part of the cartilage to another, are six in number — namely, the nuiscle of the tragus, the muscle of the antitragus, the small muscle of the helix, the large muscle of the helix, the transverse muscle of the auricle, and tlie oblique muscle of the auricle. The tragicus, the muscle of the tragus, is situated upon the outer surface of the tragus. The antitragicus, the muscle of the antitragus, arises from the outer part of the antitragus ; its fibers pass upward and are inserted into the posterior extremity of the helix. The helicis minor, the small muscle of the helix, is attached to the commence- ment of the helix and extends into the concha. This muscle is sometimes ab.sent. The helicis major, the large muscle of the helix, is situated upon the anterior margin of the lielix ; it arises above the small muscle and is inserted into the front of the helix, where it begins to curve backward. The transversus auris, the transverse muiscle of the auricle, is situated on the back of the auricle in the depression between the helix and the convexity of the concha ; it arises from the convexity of the concha and is inserted into the back of the helix. The obliquus auris, the oblique muscle of the auricle, extends from the upper back part of the concha to the convexity immediately above it. Nerve Supply. — The pinna derives its nerve .supply from the auriculo- temporal, the posterior auricular, the auricular branch of the pneumogastric (Arnold's nerve), the occipitalis minor, and the auricularis magnus nerve. Action. — The muscles of the helix assist those of the tragus and antitragus in retarding the passage of sound to the meatus. Blood Supply. — The pinna is well supplied with freely anastomosing vessels — branches of the po.sterior auricular, temporal, and occipital arteries. The veins accompany the corresponding arteries. The numerous lymphatics empty into the pre-auricular glands and into those situated upon the insertion of the .sterno-mastoid muscle. The cartilage of the pinna is a single piece, and presents the irregularities characteristic of the external ear. It is prolonged inward in the shape of a tube S— 43 G66 - SURGICAL ANATOMY. which forms the outer part of the external auditory meatus ; it is wanting between the tragus and the commencement of the helix, the interval between them being occupied by fibrous tissue. Where the helix makes its first bend, at the front part of the pinna, is a conic projection of the cartila.ge — the process of the helix. At the highest part of the helix there is not infrequently to be seen another conic projection, to which Darwin first called attention ; he regards it as tlie represen- tative of the extreme tip of the pinna of some of the lower animals. At certain places the cartilage is incomplete ; these gaps are known as fissures, and are located as follows : at the anterior part of the pinna, behind the process of the helix (fissure of the helix) ; on the surface of the tragus ; and at the lower part of the anthelix. In the piece of cartilage which forms the outer part of the meatus are two fissures — the fissures of Santorini. The pinna is attached anteriorly to the root of the zygoma and posteriorly to the mastoid process by bands of fibrous tis.sue ; in addition, there are various intrinsic ligaments, uniting the different parts. Dissection. — Turn the head to the opposite side, fix it with hooks, and work out the facial nerve and the branches of the trifacial nerve which make their exit upon the face. Expose the facial nerve by a longitudinal incision carried into the substance of the parotid gland in front of the lobe of the ear, cutting away a little of the gland Avith each movement of the knife until the nerve is seen, when it can be traced both backward and forward. The facial nerve (the seventh cranial) is the motor nerve of the face ; it consists of three portions — the intra-cranial, the temporal, and the facial. The facial portion, that which concerns us in this dissection, supplies all the muscles of expression and the platysma, the buccinator, the occipito-fi;ontalis, the attrahens, attolens, and retrahens aurem, the posterior belly of the digastric, and the stylo- hyoid. A line drawn from the anterior border of the mastoid process opposite the base of tlie loliule of the ear downward and forward across the face for about one inch will represent the course of the facial portion of the trunk of the nerve. Course. — It leaves the cranial cavity through the internal auditory meatus in company with the auditory nerve, the pars intermedia of Wrisberg, and the auditory artery. Reaching the bottom of the internal auditory meatus it enters the facial canal, or aqueductus Fallopii of the temporal bone, from which it makes its exit by way f)f tlio stylo-mastoid foramen. Passing downward and forward from the foramen it enters tlie parotid gland, crosses the external carotid artery, gives off a posterior auricular, a digastric, and a stylo-hyoid branch, and terminates in two divisions — (lie tcniporo-facial and the cervico-facial. The posterior auricular nerve, the first extra-cranial branch, passes ujjward in the groove between the ear and the mastoid process, communicates with the PLATE CLXV. Temporal br. of orbital n Supraorbital n Supratrochlear n Malar br. of facial n. Temporal br. of facial n. Great occipital n. Small occipital n. Auriculo-temporal n. nfraorbital br. of facial n. Great auricular n. Supramaxillary br. of facial n. Buccal br. of facial n. nfraorbital br. of superior maxillary n. Mental n. Infratrochlear n. Nasal n. NERVES OF SCALP AND FACIAL NERVE. 667 FACE. 6fi9 auricular brancli of tlie imoumogastric and the great auricular branch of the cervical plexus, and divides into an auricular and an occii)ital l)rancli. The auricular Ijranch supijlics the attolens and retrahens aurem muscles. The occipital branch passes along the sujwrior curved lino of the occijiital bone, supplies the occipitalis muscle, and communicates M'ith the small occipital branch of the cervical plexus. The digastric branch supplies the posterior belly of the digastric muscle, and communicates, by a twig which usually perforates that muscle, with the glosso- pharyngeal nerve. The stylo-hyoid branch is longer than the digastric ; it enters the stylodiyoid muscle about its middle, and communicates with tilaments of the sympathetic nerve on the external carotid artery. The temporo-facial, the larger of the two terminal divisions, runs obliquely upward and forward through the substance of the jmrotid gland, crosses the external carotid artery and the temporo-maxillary vein, and breaks up into the temporal, malar, and infra-orbital branches. It communicates with the auriculo- temporal nerve. The temporal branches ascend obliquely over the zygomatic arch to supply the tensor tarsi, the orbicularis palpebrarum, the corrugator supercilii, the frontalis, and the attolens and attrahens aurem muscles, and to communicate with the supra-orbital, the lacrymal, and the auriculo-temporal nerve, and with the temporo-malar branch of the superior maxillary nerve. The malar branches run across the malar bone to the outer angle of the orbit to supply the orbicularis jialpebrarum muscle, and communicate with the lacrymal and the supra-orbital nerve and with the infra-orl)ital and temporo- malar branches of the superior maxillary nerve. The infra-orbital, the largest branch, gives off a superficial and a deep set of branches, wdiich pass transversely forward over the masseter and beneath the zygomatic muscles to supply the zygomatic muscles, the elevators of the upper lip, the muscles of the nose, and the orbicularis oris muscle. The superficial branches communicate with tlie nasal and infra-trochlear nerves which are derived from the ophthalmic division of the trifacial nerve. The deep liranches form a loo]i with the l)uccal liraneh of tlie cervico-facial division, and pa.ss beneath the levator labii .superioris muscle, where they unite with the infra-orbital branch of the superior maxillary nerve, forming the infra-orbital plexus. The cervico-facial, the smaller of the two terminal divisions of the facial nerve, is joined by a branch of the great auricular nerve while in the substance of the parotid gland. It j^asses obliquely downward toward the angle of the lower jaw, crosses the external carotid artery and the temporo-maxillary vein, and divides into buccal, supra-maxillary, and infra-maxillary branches. The buccal branches 670 SURGICAL ANATOMY. pass forward over the masscter and Imccinator muscles below Stenson's duct, to the angle of tlie mouth, to sujjply the buccinator and orbicularis oris muscles, and communicate with the infra-orbital nerve, the infra-orbital branches of the temporo-facial branch, and the long buccal branch of the inferior maxillary nerve. The buccal branch of the facial nerve and the long buccal branch of the inferior maxillary nerve form a plexus over the buccinator muscle and the facial vein. The supra-maxillary branch, passes downward and forward over the masseter muscle and the facial artery, and beneath the platysma myoides and the depressor muscles of the lower lip. It supplies the muscles of the lower lip, the risorius, and the levator menti, and communicates with the buccal branch of the facial and the mental branch of the inferior dental nerve. The infra-maxillary branch emerges from the lower border of the parotid gland in front of the external jugular vein and passes downward and forward toward the sternum beneath the platysma myoides muscle, which it supplies. It communicates with the great auricular and superficial cervical nerves — branches of the cervical plexus. The infra-maxillary branch can be traced when dissecting the superficial fascia of the neck. The pes anserinus (plexus parotideus). — The breaking up of the two terminal divisions of the facial nerve within the substance of the parotid gland gives rise to a plexus, the pes anserinus (goose's foot). Bell's palsy. — Paralysis of the facial nerve is known as Bell's palsy, and may be either central or peripheral. A central paralysis is due to involvement of the nucleus of the nerve, its center in the cortex of the brain, or the fibers connecting these, and results from pressure, as by hemorrhage, abscess, or tumor ; it may also be brought about liy degenerative processes in the brain. A peripheral paralysis is due to affection of the trunk of the nerve within the cranial cavity by tumors or meningitis ; within the facial or Fallopian canal, by middle ear disease or frac- ture of the base of the skull ; external to the stylo-mastoid foramen, by a growth at the stylo-mastoid foramen, rapidly growing tumors or abscess of the parotid gland, division during an operation, or exposure of the face to cold. "When the lesion is situated beyond the origin of tlie chorda tympani nerve the muscles of expression and the buccinator muscle on the same side of the face become paralyzed, the mouth is drawn to the opposite side, and the affected side of the face becomes flattened and free from wrinkles. Through paralysis of the orbicularis palpebrarum muscle the eye on the paralyzed side remains open, and the tears run down tlie clicck. The anterior naris of the affected side is smaller in appearance through paralysis of the nasal muscles. Paralysis of the buccinator muscle causes the food to collect l)etween the cheek and the teeth of the affected side. Through paralysis of the orbicularis oris muscle the saliva dribbles from the mouth, and the jiatient can not whistle. When the lesion is situated in the aqueductus Fallopii PLATE CLXVI. OPERAIION FOR EXPOSURE OF FACIAL NERVE. 672 PLATE CLXVII. Supraorbital a. Supraorbital n. Frontal a. Infraorbital br.of facial n. Temporal br. of orbital n. Malar br.of facial n. Temporal br.of facial n. Temporal fascia Auriculo-temporal n. oral a. iricular a. facial n. Mental n! Mental a. Labial br. of infraorbital n' ^Facial a. Infraorbital n. ^ Palpebral br. of infraorbital n. ifraorbital a. 'Nasal br. of infraorbital n. TEMPORAL FASCIA AND NERVES OF FACE, 673 FACE. 675 and altovc tlie origin of the clionla tympani nerve, there is loss of the sense of taste in the anterior two-thirds of tiie tongvie on the diseased side, and through paralysis of the sta})edius muscle loud sounds are distressing. When the lesion is central or in the brain, the brow and eyelid arc not affected — /. c, the frontalis, corrugator supercilii, and orbicularis palpebrarum muscles are not involved. This is probably due to escape of the fibers which arise from the nucleus of the opposite side. Spasms, both tonic and clonic, of Ihe muscles supplied by the facial nerve may occur. Persistent spasm of these nuiscles is relieved by stretching the facial nerve. Operative exposure of the facial nerve. — The facial nerve is exposed by carrying a vertical incision from in front of the mastoid process and behind the lobule of the ear downward toward the angle of the lower jaw, laying Itare first the posterior border of the parotid gland, which is displaced foiwanl, and then the anterior border of the sterno-mastoid muscle at its insertion. The parotid gland should be separated from the mastoid process to the depth of about one centimeter, when the nerve may be seen. The exact location of the nerve in the wound can be ascertained by the use of the fiiradic battery. The trifacial nerve. — The branches of the trifiicial or fifth nerve which make their exit upon the face are the supra-orbital and the supra-trochlear (pre- viously described), the lacrymal, the infra-orbital, the malar, the anterior branch of the nasal, and the mental nerve. The lacrymal nerve, the smallest of the ophthalmic branches, supplies the lacrymal gland, and freciuently communicates witli the temporal branch of the temporo-malar nerve in the orl)it ; it sends a small filament — the palpebral — to the skin and conjunctiva around the outer canthus of the eye. The infra-orbital nerve, the terminal branch of the superior maxillary division of the trifacial nerve, emerges from the infra-orbital foramen in company with the infra-orbital artery, under cover of the levator labii supeiioris muscle. It immediately divides into palpebral, nasal, and labial branches. The palpebral branches, the smallest, pass upward beneath the orbicularis palpebrarum muscle, supply the lower eyelid, and communicate with the facial and the malar branch of the orbital or temporo-malar nerve. The nasal branches, three or four in number, pass inward under the levator labii superioris ala-que nasi muscle to supply the side of the nose, and communicate with the external (naso-labial) branch of the nasal nerve. The labial braiiclic.i, usually four, arc larger than the palpebral or nasal Ijranches, and descend beneath the levator labii superioris muscle to supply the upper lip. Beneath the levator labii superioris the branches assist in forming the infra-orbital plexus. (See description of plexus under Facial Nerve.) 676. SURGICAL ANATOMY. The infra-orbital artery, a branch of the internal maxillary, accompanies the infra-orbital nerve through the infra-orbital foramen, and divides into l)ranches which are distributed like those of the nerve. It anastomoses with the transverse facial, facial, and ophthalmic arteries. The infra-orbital vein communicates with the facial vein in front, and empties into the pterygoid plexus of veins. The malar division of the orbital or temporo-malar branch of the superior maxillary nerve makes its exit through a foramen in the malar bone, pierces the orbicularis palpebrarum muscle, and supplies the skin of the cheek covering the malar bone. It communicates with the facial and the palpebral branches of the infra-orbital nerve. The external or terminal branch of the nasal nerve, also known as the naso-labial, emerges between the nasal bone and the lateral cartilages of the nose, supplying the tip of the nose as it descends beneath the compressor narium muscle. It communicates with the infra-orbital branches of the facial and trifacial nerves. The mental nerve, the continuation of the inferior dental, emerges from the mental foramen in company with the mental artery. It divides beneath the de- pressor anguli oris muscle into three branches, the smallest of which descends to supply the chin, while the other two ascend to supply the lower lip. It inosculates with the supra-maxillary branch of the facial nerve. The mental artery, the terminal portion of the inferior dental, supplies the chin and anastomoses with the submental, inferior labial, and inferior coronary arteries. PTERYGO-MAXILLARY REGION. The pterygo-maxillary region is the space included between the ramus of the lower jaw, externally ; the lateral wall of the pharynx and the pterygoid process of the sphenoid bone, internally ; the zygomatic surface of the- superior maxilla, anteriorly ; and the lower surface of the greater wing of the sphenoid and the adjacent temjioral bone, above. The posterior limit of the space is represented by a plane passing directly inward from the posterior border of the ramus of the inferior maxilla to the pharynx. Dissection. — The zygomatic arch should be removed by sawing through the zygomatic jirocesscs of both the malar and temporal l)nnes. In tlie latter, the point selected sliould l>e ju.st in front of the tubercle of the zygoma. Reflect the masseter muscle from the ramus of the inferior maxilla, carrying the zygoma with it ; locate the masseteric artery and nerve which pass through the sigmoid notch of the lower jaw ; trace them into the masseter muscle as far as possible, and then .sever them. A portion of the ramus of the lower jaw should be PLAIE CLXVIll. Anterior deep temporal a Superior maxillary n. Anterior temporal n. Posterior temporal n Posterior deep temporal a. Masseteric n. Temporal m. Orbital n. infraorbital a Buccinator Auriculo-temporal n. Superficial temporal a. sseteric a. sverse facial a. al maxillary a. dental a. uricular a. tal n. tid a. Posterior superi Alveolar a! Buccal a' Buccal n External pterygoid m'. Lingual n PTERYGOID MUSCLES AND INTERNAL MAXILLARY ARTERY. G78 FACE. 079 removed in the following manner : With Hcy's saw cut downward behind the last molar tooth, halt' way thnnigh the body of the jaw, then Ijackward to near the angle. Discard the saw M-hen it reaches the cancellous tissue, and use the chisel to avoid division of the inferior dental vessels and nerve. The saw should now be directed downward from the sigmoid notch, just in front of the neck of the jaw, through the ramus to the end of the incision in the body of the bone. The removal of this portion of the inferior maxilla is tedious, as the internal pterygoid muscle, internal lateral ligament, and the inferior dental vessels and nerve oppose elevation of the section of bone thus separated. Remove the posterior inferior corner of the section of the ramus with bone forceps as far as the inferior dental canal, which contains the inferior dental vessels and nerve ; then reflect the b(ine with the lower jiortion of the temporal muscle, taking care to avoid destroying the mylo-hyoid arterj' and nerve which arise from the inferior dental artery and nerve, near the inferior dental foramen, and pass downward and forward in a groove on the internal surface of the ramus. In making this dissection it is advisable to use the back of the point of the scalpel, as the vessels and nerves are small, of delicate structure, and are easily severed. The contents of the pterygo-maxillary region are the internal and external pterygoid muscles, the internal maxillary artery with some of its branches and their companion veins, the pterygoid plexus of veins, the infei'ior maxillary nerve, and the following branches of that nerve : The anterior and posterior deep temporal, long buccal, masseteric, internal and external pterj'goid, inferior dental, auriculo-temporal, ami lingual nerves, the chorda tympani nerve, a portion of the parotid gland, the internal lateral ligament of the lower jaw, and the internal maxillary lymphatic glands. The internal maxillary artery, which is closely related to the nerves of this region, passes forward either over or behind the external pterygoid muscle. The internal lateral ligament is a thin, fibrous band which lies beneath the inferior dental vessels and nerve ; it passes, with the lingual and inferior dental nerves, through the triangular interval between the two pterygoid muscles and the incised edge of the jaw. The external pterygoid muscle, the more superficial of the two pterygoids, arises by an upper head from that portion of the greater wing of the sphenoid bone situated between the pterygoid ridge and the foramina ovale and spinosum ; by a lower head from the outer surface of the external pterygoid ]ilate of the sphenoid Ijone, from the tuberosities of the palate and superior maxillary bones. Its fibers pass horizontally backward and converge for insertion into the inter- articular fibro-cartilage of the temporo-maxillary joint superiorly, and inferiorly into the anterior portion of the inner surface of the neck of the inferior maxilla. 680 SURGICAL ANATOMY. It is related, externally, with the ramus of the inferior maxilla, the temporal and masseter muscles, the superficial ])ortion of the internal pterygoid muscle, the internal maxillary artery, the anterior and posterior deep temporal arteries, and the buccal artery and nerve. Internally, it is in relation with the deep part of the internal pterygoid muscle, the middle meningeal artery, and the inferior maxillary nerve, the internal lateral ligament of the lower jaw, the lingual and inferior dental nerves, which emerge from beneath its lower border ; the long buccal nerve, which runs between its two heads ; the chorda tympani nerve, and the anterior and posterior deep temporal and masseteric nerves, which pass out from beneath the upper border of the muscle. Blood Supply. — From the external pterygoid branches of the internal maxil- lary artery. Nerve Supply. — From the inferior maxillary nerve. Action. — Tlie external laterygoid muscles acting together pull the lower jaw forward ; alternately, they move it forward and laterally ; and, singly, forward and to the opposite side. They are muscles of trituration. The internal pterygoid muscle (the internal masseter) arises by two heads, a superficial and a deep. The superficial, the smaller, arises from the lower and back part of the tuberosity of the upper jaw, and the outer side of the tuberosity of tlie palate bone. The deep lies beliind the lower head of the external pterygoid and arises from the internal surface of the external pterygoid plate, and from the grooved portion of the tuberosity of the palate bone situated in the pterygoid fossa. These two heads unite at the lower margin of the external pterygoid muscle, and thence extend downward, backward, and outward for insertion into the rough irtner surfiice of the pcsterior portion of the ramus of the lower jaw included between the angle and the inferior dental foramen. It is related, externally, with the ramus of the lower jaw, the external pterygoid muscle, the internal lateral ligament of the lower jaw, the lingual or gustatory nerve, and inferior dental and mylo-hyoid vessels and nerves ; internally, with the tensor palati, stylo-glossus, stylo-hyoid, posterior belly of the digastric, and tlie superior constrictor muscle of the pharynx. Blood Supply. — From the mylo-hyoid and internal pterygoid branches of the internal maxillary artery. Nerve Supply. — From the internal pterygoid branch of the inferior maxillary nerve. Action. — Both internal pterygoid muscles acting together draw the lower jaw upward and fovAvard ; and, singly, u])ward and to the oppo.site side. The internal maxillary artery, the larger of the two terminal branches of the external carotid, arises in the parotid gland, opposite to or slightly lower than S— 44 PLATE CLXIX, Infraorbital a. Orbital b Palpebral b Anterior dental br. Nasal br.- Labial br. Posterior dental a Gingival br.of posterior dental a Spheno-palatine a. Pterygo-palatine a. /Vidian a. Decending palatine a. Anterior deep temporal a External pterygoid a. Posterior deep temporal a. Small meningeal a. Middle meningeal a. Superficial temporal Typanic a. Deep auricular a. nternal maxillary a External carotid a Mylo-hyoid a. Submental a. Mental a. Incisive br. Masseteric a. Internal pterygoid a. nferior dental a. Buccal a. ETERNAL MAXILLAKY AKILRY AND BRANCHES. ()82 FACE. 683 the neck of tho lower jaw. The artorv is divided into tlirce portions : maxillary, pterygoid, and spheno-niaxillary. The Jirsf or maxillary porlion passes forward between the internal lateral ligament and tlu> neek of tho lower jaw, and reaches the lower margin of tho external pterygoid nuiscle. The second or pterygoid portion extends obliquely upward and forward upon the outer surface of the external pterj'goid muscle, and is hidden by tiie insertion of the temporal muscle. The third or spheno-maxillary portion lies in the spheno-maxillary fos.sa. In some instances the second or pterygoid portion runs entirely beneath the external pterygoid muscle, but, by jiassing between the two heads of that muscle, appears upon the outer surface of the muscle just before entering the spheno- maxillary fossa. The branches of the first or maxillary portion of the internal maxillary artery are : The deep auricular, tympanic, middle meningeal, small meningeal, and inferior dental arteries. The deep auricular artery pierces the wall of the external auditory canal to supply the tj'mpanic membrane. The tympanic artery passes behind the temporo-maxillary joint through the Glaserian fissure to supply the tympaimm. The middle meningeal artery runs upward between the two roots of the auriculo-temporal nerve to the foramen spinosum, through which it enters the cranial cavity to supply the cranium and dura mater. The sinall meningeal artery ascends to the foramen ovale, through which, after supplying a twig to the nasal fossa and soft palate, it enters the cranial cavity. The inferior dental artery, with its vcnaj comites, accompanies the inferior dental nerve and passes downward, upon the internal pterygoid muscle and the internal lateral ligament, entering the inferior dental foramen together with the inferior dental nerve. The artery then occupies the inferior dental canal, dis- tributing branches to the teeth ; it supplies an incisive branch, and emerges, on the face, from the mental foramen; it is then called the mental artery; the mental arterj' is accompanied l)v the mental nerve, and is distributed to the structures of the chin and lower lip. Before entering the inferior dental canal the inferior dental artery gives off the mylo-hyoid artery, which accompanies the mylo-hyoid nerve. The branches of the second or pterygoid portion are the anterior and posterior deep temporal, internal and external pterygoid, and the masseteric and buccal arteries. The anterior and posterior deep temporal arteries pass upward through the corresponding parts of the temporal fossa, between the temporal muscle and the pericranium, which they supply. 684 SURGICAL ANATOMY. The pterygoid arteries, varying in number, supply the external and internal pterygoid muscles. The masseteric artery, with the masseteric nerve, passes outward behind the temporal muscle through the sigmoid notch of the lower jaw to the masseter muscle. The buccal artery accompanies the long buccal nerve in its forward course between the ramus of the lower jaw and the external i^terygoid to the buccinator muscle. The branches of the third or splicno-maxillary j)ortion are the alveolar, infra- orbital, posterior or descending palatine, Vidian, pterygo-palatine, and naso- palatine or spheno-palatine arteries. The alveolar [posterior superior dental or posterior dental) artery gives off branches to the gums and the buccinator muscle, enters the superior maxilla at its zygomatic surface, and supplies the molar and bicuspid teeth and the mucous lining of the maxillary sinus or antrum of Highmore. The infra-orbital artery immediately enters the infra-orbital groove and canal, accompanied by the superior maxillary division of the fifth pair of cranial nerves, and eventually emerges upon the face in company with the infra-orbital nerve at the infra-orbital foramen. It supplies branches to the orbit, and gives off an anterior superior dental branch, which runs downward in the anterior wall of the maxillary sinus and supplies the incisor and bicuspid teeth and the mucous membrane of the maxillary sinus. The posterior or descending palatine artery accompanies the posterior palatine branches of Meckel's or the spheno-palatine ganglion of the fifth pair of cranial nerves, through the posterior palatine canal, then emerges from the posterior palatine foramen, and passes forward in a groove situated near the alveolar process along the under surface of the hard palate ; it next enters the foramen of Stenson, a subdivision of the anterior palatine foramen, and anastomoses with the naso- palatine artery. It is distributed to the hard and soft palate, palatine glands, and gums. The Vidian artery runs backward with the "\^idian nerve through the Vidian canal to supply the uppermost part of the pharynx, the Eustachian tube, and the tympanum. The pterygo-palatine artery, which is very small, passes Ijackward witli the pharyngeal nerve through tlie ])tery go-palatine canal to supply the upper pharynx, the sphenoid cells, and the Eustachian tube. The naso-palatine or spheno-palatine, the terminal artery, runs inward through the naso-palatine or spheno-palatine foramen into the superior meatus of the nose. It crosses the roof of this meatus between the mucous membrane and the bone to PLATE CLXX, al temporal a. riculo-temporal n. Anterior deep temporal a Anterior temporal n Orbital n. Superior maxillary n.. Meckel's ganglion- Infraorbital a.- Posterior superior dental n Posterior temporal n Long buccal n Chorda tympani n Lingual n Internal lateral ligament of lower ja Buccinator m.- Inferior dental n Inferior dental a INFERIOR MAXILLARY NERVE. 686 FACE. 687 roai'h the se[)tuiu of llio nose, runs dowiiwaril and forward in a groove on the vomer, to anastomose with tlie posterior i)aiatine artery. Two or three external l)ranelies are distributed to the mucous lining of the lateral nasal walls, the antrum of Highmore and the ethmoid and sphenoid cells. Tlie veins of the pterygo-maxilhny region accompany the branches of the internal maxillary artery, and converge toward the external pterygoid muscle, aniund wbicli they form a di'nse jilexus — the pterygoid plexus. This is drained fnmi its posterior part by a short venous trunk, called the internal maxillary vein, wliicii accompanies the first (maxillary) portion of tlie internal maxillary artery into the substance of the parotid gland. The internal maxillary vein joins the temporal vein to form the temporo-maxillary vein. The pterj-goid plexus sends a branch (anterior maxillary or deep facial vein) from its anterior part over the buccinator muscle to the facial vein. It also communicates with the cavernous sinus by means of a small emissary vein which passes through the foramen Vesalii in tlie sphenoid bone. The lymphatics of this region accompany the blood-vessels, and are derived from the regions which those vessels supply and drain. They empty into the deep cervical glands. The nerves of the pterygo-maxillary region are the inferior maxillary division of the fifth nerve and some of its branches and the chorda tympani nerve. The inferior maxillary nerve leaves the cranial cavity through the foramen ovale. It emerges fi'om the skull as a thick trunk, which lies external to the Eustachian tube aird beneath the external pter^'goid muscle. It differs from the other two divisions of the fifth nerve — the ophthalmic and the superior maxillary — in lieing composed of both motor and sensory fibers. After leaving the skull it divides into two portions, an anterior and a posterior. From the anterior portion, chiefly motor, are derived the anterior and posterior deep temporal nerves, the masseteric nerve, branches to the pterygoid muscles, and the long buccal nerve. The posterior divi- sion, chiefly sensory, divides into three large branches: the auriculo-temporal, the lingual (gustatory), and the inferior dental nerve. The deep temporal nerves, anterior and posterior, arise from the motor root of the fifth nerve, and ascend between the perici'anium and the temporal muscle, which muscle they supply. The masseteric nerve emerges from between the external pterj'goid muscle and the pterygoid ridge. It proceeds backward along the upper border of the external pterj'goid muscle ; outward in front of the temporo-maxillarj' articulation, and through the sigmoid notch of the lower jaw, together with the masseteric artery, entering the niasseter muscle, which it supplies. The branch to the internal pterygoid muscle arises from the inferior maxil- 688 SURGICAL ANATOMY. lary nerve before it divides ; it gives off a l)ranch to the otic ganglion, and enters the deep surface of the muscle. The branch to the external pterygoid muscle is, usually', a twig of the long buccal nerve, and divides into two luanchcs, which enter the deep surface of the muscle. The long buccal, a sensory nerve, is derived from the anterior portion . of the inferior maxillary division of the fifth nerve. It runs between the two heads of the external pterygoid muscle, and passes downward and forwai-d lieneath the temporal muscle and the anterior edge of the masseter to the buccinator muscle, upon the outer side of which it communicates with the facial nerve and forms a plexus from which filaments pass to the adjacent mucous membrane and skin of the cheek. It contains all of the sensory fibers of the anterior division of the inferior maxillary nerve, and a few fibers from the motor root of the fifth nerve. The motor fibers run to the external pterygoid and temporal muscles. The auriculo-temporal nerve arises by two roots, between which pas.ses the middle meningeal artery. It runs backward and outward beneath the external pterj'goid muscle, between the internal lateral ligament and the temporo-maxillarj'^ joint, curves outward around the neck of the cond3'le of the lower jaw, and pierces the upper part of tlie parotid gland. It next ascends over the root of the zygoma, in front of the external auditory meatus and beneath the temporal arterj'. In its course it receives communicating twigs from the otic ganglion, and supplies branches to the external auditory meatus, the parotid gland, and the temporo- maxillary articulation. From the parotid gland it sends a communicating branch to the temporo-facial division of the facial nerve. It divides near the level of the tragus into the anterior auricular and superficial temporal branches. The anterior auricular supplies the upper part of the pinna. The superficial temporal lies on the outer side of the superficial temporal vessels, divides, and accompanies the anterior and posterior temporal arteries. The lingual (gustatory) nerve emerges from beneath the lower edge of the external pterygoid muscle, whence it descends internal to the inferior dental nerve between the lower jaw and the internal pterygoid muscle; thence it runs licnoath the mylo-hyoid nerve and over the superior constrictor of the pharynx, the stylo- glossus, hyo-glos.sus, Wharton's duct, and gcnio-hyo-glossus muscle, to the tip of the tongue. On the hyo-glossus muscle it is connected with the submaxillary ganglion, which will be described with the submaxillary triangle of the neck. It lies above the ganglion and Wharton's duct, which it crosses at the anterior border of the hyo-glossus muscle, M'here it supplies a branch to the sublingual gland and a communicating l)ranch to the hyjio-glossal nerve. Before it emerges from behind the external pterygoid muscle it is joined by the chorda tympani nerve. The lingual nerve supplies branches to the hypo-glossal nerve, submaxillary PLATE CLXXI, Nasal n. Olfactory n. Olfactory tract Superior nasal nerves Spheno-palatine n. Meckel's ganglion Vidian n. Pharyngeal n. Nasopalatine n. tiaso-palatine n Interior nasal nerves Great palatine nl External palatine n. Posterior palatine n! Tensor palati m'. Internal pterygoid m. Otic ganglion Sympathetic root of otic gang'. Middle meningeal a. Auriculo-temporal n.' OLFACTORY NERVES AND INTERNAL VIEW OF THE SPHEf 690 -PALATINE AND OTIC GANGLIA. FAVK. 691 jj;anain ihu' to neuralj^ia or cancer of the tongue may he relieved by division of this nerve. The incision should be made through the mucous membrane of the floor of the mouth opposite the second molar tooth of the lower jaw and close to the gum, where the nerve lies innnediately heiH'ath the mucous memlirane. The inferior dental nerve, the largest branch of the inferior maxillary, emerges from beneath the lower heail of the external pterygoid muscle and de- scends between the internal lateral ligament and the ramus of the lower jaw to enter the inferior dental canal. At its origin it lies internal to the inferior dental artery, which it crosses at the inferior dental foramen ; the artery is, therefore, nearer the teeth than the nerve. It is a sensory motor nerve, Ij'ing external to the lingvial nerve and more sn]ierficial, the motor filaments being given off as the mylo-hyoid nerve just jirevious to its entrance into the inferior dental canal. The mylo-hyoid nerve is accompanied by the mylo-hyoid artery, pierces the internal lateral ligament of the lower jaw, and descends to the mylo-hyoid groove upon the inner surface of the lower jaw. It then runs over the superficial surface of the mylo-hyoid muscle, sujtplying it and the anterior belly of the digastric muscle. In tlie inferiiir dental eanal the inferior dental nerve supplies branches to tlie molar and bicuspid teeth and to the gums, and divides into an incisive and a mental branch opposite the mental foramen. The incisive branch passes forward and inward in the inferior dental canal to supply the canine and incisor teeth and the adjacent region of the gum. The mental branch emerges ujion the face at the mental foramen, and after commimicating with the supra-maxillary branch of the facial nerve divides into several branches. These supply the mucous membrane of the lower lip and the fascia and skin of the lip and chin. The chorda tympani nerve arises from the facial in the aqueductus Fallopii, almost one-fourth of an inch above the stylo-mastoid foramen. It runs in the iter chorda; posterius to the middle ear, where it passes between the hamlle of the malleus and the fibrous layer of the membrana tympani externally, and the mucous membrane internally. It next enters the iter chordre anterius, or canal of Huguier, to reach the pterygo-maxillary region, where it joins the outer side of the lingual nerve beneath the external pterygoid muscle. Some of its Hbers leave tlie lingual nerve to enter the submaxillary ganglion and sublingual gland. The otic (Arnold's) ganglion lies upon the internal surface of the trunk of the inferior maxillarv division of the fifth nerve, in front of the middle 692 SURGICAL ANATOMY. meningeal artery, and may be found by tracing any of the larger branches of the nerve until the root of the parent stem, near the foramen ovale, is reached. Its sj'Uipathetic root is derived from the j^lexus on the middle meningeal artery ; its sensory root from the inferior maxillary through the internal pterygoid nerve ; its motor root from the small superficial petrosal nerve, which communicates with the tympanic branch of the glosso-pharyngeal nerve. It communicates with the auriculo-temporal and chorda tympani nerves. ^lotor fibers of the inferior maxillary nerve pass through it to the tensor palati and tensor tympani muscles. Dissection. — To study the first portion of tlie internal maxillary arterj' and its branches, the trunk of the inferior maxillary nerA-e, tlie origins of its branches, and the otic ganglion, it is necessary to remove the external pterygoid muscle, the condyle of the jaw, and the remainder of the ramus as far as the transverse incision in the ramus. Fracture of the base of the skull may cause serious hemorrhage into the pterygo-maxillary region, because of rupture of the meningeal vessels. Lacerations of the deep temporal vessels due to cranial fracture would result in the effusion of blood into this space, its escape above the zygoma being rendered impossible because of the attachments of the temporal fascia. Under these conditions pain on jiressure made below the zygoma and behind the malar bone would be a rational symptom. Such eff'usion might give rise to secondary irritation of the nerves in this space. Thus, irritation of the chorda tympani nen'e would cause sali- vation ; of the lingual, disturbances of sensation and taste at tlie end of the tongue ; of the inferior dental, toothache ; of the motor branches, tonic or clonic spasms of the muscles of mastication ; of the niylo-hyoid and anterior bellj' of the digastric muscles, more or less complete fixation of the jaw. Tumors and abscess would have similar effects, but would vary in degree in accordance with the exact location and rapidity of growth. Owing to the presence of imjwrtant structures in this space, it is well to practise Hilton's method of opening a deep abscess in this region ; this is done as follows : Tlirough an incision in the skin push a grooved director into the abscess ; then insert a jmir of forceps along the director, and withdraw them with the blades sufl[icient]y separated to make an opening large enough to insure good drainage. It is im- possible to do serious damage by this procedure. Dissection. — The pterygo-maxillary region sliould now be thoroughly cleaned, in order to study the spheno-maxillary fissure, the pterygo-maxillary fissure, and tlie spheno-maxillary fossa. It will be remend^ered that tlie zygomatic fo.ssa was mentioned in connection with the contents of the pterygo-maxillary region ; its contents have been dissected. FACE. 693 They consist of the lower part of tlic tiiuiMiral muscle, tlie internal and exlt^rnal pterygoid nm^cles, the internal maxillary artery, the inferior maxillary nerve, branches of the artery and nerve, ami the chorda tympani nerve. The zygomatic fossa practically corresponds to the upper portion of the pterygo-maxillary region. It is hoinided above by the under surface of the great wing of the sphenoid and adjacent portion of the temporal bone ; in front, by the zygomatic surface of the superior maxilla ; behind, by the posterior border of the pterygoid process of the sphenoid bone and the erainentia articularis ; internally, by the external pterygoid plate ; and externally, by the pterygoid ridge, the zygo- matic arch, and the ramus of the inferior maxilla. At the upper and inner part of the zygomatic fossa two fissures will be ob.served, one horizontal, the other vertical. The horizontal fissure is the spheno-maxillary, which opens into the outer and back part of the orbit. It transmits the infra-orbital artery and vein, branches from Meckel's ganglion, and the superior maxillarj^ nerve and its orbital branch. Its bony walls are formed, above, by the lower border of the orbital surface of the great wing of the sphenoid ; below, by the orbital surface of the superior maxilla and a portion of the palate bone ; externally, by a small part of the malar bone. It joins the pterygo-maxillary fissure at a right angle. The vertical fissure is the pterygo- maxillary, which is formed by the angle between the superior maxillary bone and the pterygoid process of the sphenoid bone. It transmits the internal maxillary artery. The spheno-maxillary fossa lies below the great wing of the sphenoid, external to the vertical portion of the palate bone, and between the orbital process of the palate bone and the zygomatic surface of the superior maxilla, in front, anharynx and the Eustachian tube. Tlie Vidian nerve lias licen considered a posterior branch of the spheno- palatine ganglion, but it is really the nerve which is formed by the junction of its motor and sympathetic roots. It will be seen emerging from the Vidian canal at tlie root of the pterygoid process. The superior maxillary nerve and its many communications are especially important, because it is .so frequently affected by neuralgia, the operation for which follows. Trifacial neuralgia may be due to many causes ; among these are: Reflected irritation fi'nm diseased teeth, erujition of the wisdom teeth, irritable ulcers in the FACE. 699 area of distribution of the norvc, and abscess or tumors of the antrum of IIi<,diniore, of the pterysj;<)-maxillarv region, or of the spheno-maxilhiry fossa. Tiie infra-orbital foramen is on a line drawn from tlie supra-orbital notch to a point between the bicuspid teeth of the upper jaw. It corresponds to a ])oint about one-half (if an inch below the junction of the inner and the middle one-third of the infra-orbital margin. The infra-orbital nerve is best exposed through a .semilunar incision with its convexity directed downward, and carried a short distance below the foramen. A flap, including skin, cellulai: tissue, and the orbicularis palpebrarum muscle, is raised. The levator labii superioris muscle, which covers the foramen, is now aii])arent, and must lie displaced laterally or divided, when both the ini'ra -orbital plexus and nerve will readily be found, surrounded by a small quantity of fatty tissue. In some cases of obstinate neuralgia of the peripheral branches of the trifacial nerve it becomes necessary to remove a portion of the affected nerve in order to give the jiatient relief The infra-orbital nerve may be divided at its exit from the infra-orbital foramen by either a subcutaneous or a conjunctival section ; in the latter method the tenotome is introduced through the conjunctiva and carried over the infra-orbital margin ; it is best to expose the infra-orbital nerve by turning up a flap from the face, when a portion of the nerve can be removed. The nerve being exposed and freed at its point of exit, a slightly curved or hooked knife can be entered close to the external canthus just below the outer palpebral ligament, and passed backward along the floor of the orbit toward the apex, and along the anterior border of the spheno-maxillary fissure, which is crossed by the nerve at about an inch behind the orbital margin. The knife is then carefully withdrawn, and the nerve divided as it enters the infra- orbital canal. Traction is then made upon the peripheral end of the nerve to remove it from the infra-orbital canal. Should the knife be carried too far and the spheno-maxillary fossa be entered, serious hemorrhage would result. The objections to this last method are, first, the hemorrhage which results from the division of the infra-orbital vessels inaccessible for ligature ; second, the uncertainty of accomplishing the division of the nerve ; and third, in many of these cases the posterior, as well as the anterior, dental branches arc involved ; if this be the case, removal of the superior maxillary nerve behind Meckel's ganglion will be required in order to insure positive relief. The liest method for removing the superior maxillaiy nerve through the face from behind Meckel's ganglion is the following : Expose and free the infra-orbital ners'e at its exit from the infra-orbital foramen ; then, with a three-quarter-inch trephine, remove a button of bone from the anterior wall of the antrum of High- more ; this button should include the outer wall of the infra-orbital foramen, and 700 SURGICAL ANATOMY. in removing it care must he taken not to sever the infra-orbital nerve. Open the antrum by tearing through the Uning membrane, and then, with a trephine one- half of an inch in diameter or with a small chisel, perforate its posterior wall. This opens up the spheno-maxillar}' fossa, and w'ill be followed by considerable bleeding from wounded branches of the internal maxillary vessels. Before pro- ceeding with the next step in the operation pack the opening in the posterior wall with sterile gauze to check the hemorrhage ; then, with a small chisel, break away the floor of the infra-orbital canal and the back part of the floor of the orbit along the roof of the antrum ; this permits the infra-orbital nerve to be drawn down into the antrum, wheU; b}^ making slight traction upon it, a pair of long, slender scissors, sharply curved and with blunt points, can be carried along the nerve through the antrum, and the superior maxillary nerve divided behind Meckel's ganglion. In breaking away the floor of the infra-orbital canal the infra-orbital vessels will be torn, but the bleeding therefrom is of no serious consequence and can be controlled by packing a strip of sterile gauze into the broken canal. If hemorrhage persist after the removal of the superior maxillary nerve, the splieno-maxillary fossa also may be packed with gauze, which should protrude through the opening in the anterior wall of the antrum. The gauze may remain for two or three days and serves a two-fold purpose : in controlling the bleeding and in favoring drainage. The operation is facilitated by the use of an incandescent lamp attached to a head-band. Clavus (nail) is the name given to a neuralgic pain, which, from its intensity and the smallness of its area, is likened to a nail being driven tiirough the flesh and bone. It generally affects hysteric young women. It is not inappropriate for the author to say here that, having had a large experience in the operative treatment of cases of trigeminal neuralgia (tic doulou- reux), he is of the opinion that the simpler operative procedure should first be pursued, for the period of relief following any operation is, comparatively speak- ing, but temporary in the majority of cases. This is not in accord with the views of some of the leading operators, but it has, nevertheless, been the author's experi- ence. He has operated on a number of cases several times, — in one instance as many as five, — each operation having been followed by relief for from twelve to eighteen months. The peripheral operations may be repeated, a little more of the nerve being removed at each operation. This course affords the patient a more prolonged jioriod of relief tliau could l)e obtained by first performing the more radical operation. As a last resort, the most radical operation of all, intra-cranial section of the affected nerve or removal of the Gasserian ganglion, may be done. In cases where the neuralgia has returned after removal of the superior maxillary nerve back of Meckel's ganglion by opening both walls of the antrum and removing FACE. 701 the infra-orbital nerve from its canal, flie author has, bj' sinij)!}' cleaning out the track of the original wound, seen JvWvi' foiidw. In trifacial neuralgia one, two, or all three branches of the trifacial nerve may be involved. The oiihthahnic division supplies the skin above the palpebral fissure ; the superior maxillary division, the skin between the palpebral and oral fissures, including the temple ; the inferior maxillary division supplies the skin below the oral fissure as far as the liyoid bone. The superior and the inferior maxillary nerves also supply the teeth through their branches, while the latter supplies the anterior two-thirds of the tongue through its lingual branch ; the motor root of the third division also supplies the muscles of mastication, except the buccinator — i e., the temporal, masseter, and external and internal pterygoid muscles. Thus, complete paralysis of the trifacial nerve abolishes sensation upon one side of tlie face and on top of the head, from the highest point of the vertex above to the hyoid bone below ; laterally, to and including the front of the ear and external auditory canal and temple ; mesially, the anterior nares and the sensibility as to touch and taste of the anterior two-thirds of the tongue, besides completelj' paralyzing the muscles of mastication on the affected side, witli the exception of th6 buccinator. Because of the insensibility of the conjunctiva the lids do not properl^y protect this mem- brane, and it becomes congested and inflamed, a condition which often occurs spontaneously through implication of the troi)hic fibers of the trifacial nerve. At the same time anterior rhinitis may result from similar causes, or may be excited by the discharge of the conjunctival secretion into the inferior meatus of the nose. Trifacial neuralgia may be accompanied by active implication of the trophic filaments, so that there is not only conjunctivitis and rhinitis, ])ut vesicles may form upon the lips and anterior nares. This should be borne in mind, as these trophic nerve disturbances, when overlooked, may be the source of much per- plexity to the physician. Paralysis of the orbicularis palpebrarum muscle also leads to conjunctivitis, from inability to close the eyelids ; this must not be confounded with the inllani- mation of perverted function of the tro]>!iic nerves. The trophic filaments arc derived from the sympathetic nerve ; this is a general rule worth remembering. The entire width of the occiput, as high up as the vertex, and tlie l)ack of the pinna are supplied by the occipitalis major ners-e. As Hilton pointed out, tlie pinna may, therefore, often be used to differentiate between spinal and cerebral central ner\-e disease causing neuralgia ; if spinal, the back of the ])iinia is affected and the front is not ; if cerebral, the signs are reversed. Reflex or referred pains are frequent in the area of distribution of the trifacial 702 SURGICAL ANATOMY. nerve because of the abundance of its filaments and their numerous inosculations. The physician must, therefore, be careful not to be misled by the location of pain, for an earache may be due to a diseased tooth, as was the case in a patient treated by Hilton : Tlie patient had consulted several leading aurists for a persistent earache without obtaining relief except from the use of anodynes ; the ingenious Hilton sagaciously concluded it to be useless to treat where so many others had failed, and looked elsewhere than at the ear for the cause of the ti-ouble. This he found in a jagged molar tooth which was continually irritating a small nerve filament at the Ijottom of an ulcer upon the side of the tongue adjoining the tooth. He advised the removal of the tooth, which resulted in healing of the ulcer and in cure of the earache. In a similar manner affections of any filament of the trifacial nerve may produce pain in any part supjilied by other branches of the nerve. The Lymphatic Glands of the Head are divided into a superficial and a deep set. The superficial set is composed of the occipital, posterior auricular, parotid, buccal, and submaxillary lymphatic glands. The occipital or suboccipital lymphatic glands are situated in the superficial fascia along the superior curved line of the occipital bone over the attachments of the trapezius muscle and the occipital belly of the occipito-frontalis muscle. These glands receive the lymphatic vessels from the posterior portion of the scalp or that area supplied by the occipital artery, and may be involved in erysipelas or other septic conditions of the posterior portion of the scalp. The efferent vessels from these glands empty into the superficial lymphatic glands of the neck. The posterior auricular or mastoid lymphatic glands are situated behind the pinna, over the mastoid process and the insertion of the sterno-mastoid muscle. They receive the lymphatic vessels from the posterior auricular region and the portion of the scalp above it. Their efferent vessels empty into the superficial lymphatic glands of the neck. The parotid lymphatic glands lie upon the parotid salivary gland in front of the pinna, below the zygoma, and a few are found in the substance of the parotid salivary gland. They receive the lymphatic vessels from the temporal region, the portion of the scalp above it, and the outer portion of the eyelids and of the cheek. Their eift'n'nt vessels empty into the superficial lymphatic glands of the neck and into the submaxillary lymphatic glands. The buccal lymphatic glands rest upon the buccinator muscle. They receive some of the lymjiiiatics from the anterior portion of the face, inner half of the eyelids, brow, and front of the scalp. Their efferent vessels empty into the submaxillary and tiic intiimd maxillary lymphatic glands. The submaxillary lymphatic glands are the largest group. They are FACE. 703 situated below the border of the lower jaw, ninst of tlu'in lyinn; in the submaxillary triangle in relation witli the sulimaxillary salivary gland ; two or three ol' tlieni (supra-hyoid lyniiiliatics) lie above the body of the hyoid bone, between the ante- rior bellies of the two digastric muscles. The submaxillary lymi)hatic glands receive the lymphatic vessels from the fnint of the scalp, inner jiart of the eyelids, anterior portion of the face, tloor of the nmuth, anterior portion of the tongue, sul)lingual and submaxillary salivary glands, and some of the ett'erent vessels from the parotid lymphatic glands. Their efferent vessels emjity into the superficial and deep cervical lymphatic glands. The deep lymphatic glands of the head are the internal maxillary, lingual, and post-jiharyngeal lymphatic glands. The internal maxillary lymphatic glands are situated in the pterygo-maxil- lary region ; some are in relation with the internal maxillary artery, others lie upon the posterior portion of the buccinator muscle, and still other deep glands lie upon tlie side of the pharynx. They receive the lymphatic vessels from the orbi- tal, nasal, temporal, and zygomatic fo.ssa>, the roof of the mouth, and the .soft palate, and some of the efferent vessels from the buccal lymphatic glands. Their efferent vessels empty into the deep cervical lymphatic glands and partly into the deep parotid lymphatic glands. The lingual lymphatic glands lie upon the hyo-glossus and genio-hyo-glossus muscles. They receive the lymphatic vessels from the upper surface and posterior part of the tongue. Their efferent vessels unite with the upper glands of the deep cervical chain. The post-pharyngeal lymphatic gland is situated below the base of the skull, between the posterior wall of the pliarynx and the rectus capitis anticus major muscle. It receives the lymphatic vessels from the upper part of the pharynx, jRirt of the nasal fossa, and the upper part of the prevertebral muscles. The lymphatic vessels of the scalp, which drain that portion behind a ver- tical line passing through the external auditory meatus, terminate in the occipital and posterior auricular lymphatic glands ; the lymphatics of the temporal region of the scalp and that portion above it empty into the superficial and deep parotid lymphatic glands ; the lymphatic vessels of the frontal region of the scalp follow the frontal, supra-orbital, and the facial veins downward over the face to the sub- maxillary lymphatic glands. The lymphatic vessels of the face are divided into a superficial and a deep set. The superficial lymphatics of the anterior portion of the face — /. c, of the inner half of the eyelids, of the nose, lips, and anterior part of the cheek — pass downward into the submaxillary lymphatic glands, and those of the outer half of 704 SURGICAL ANATOMY. the eyelids and outer part of tlie cheek terminate in the parotid lymphatic glands. The deep lymphatics of the face — i. e., those of the orbit, part of the nasal fossa, the hard and soft palates, deeper portion of the cheek, temporal fossa, and pterygo- maxillary region — enter the internal maxillary lymphatic glands. From the course of the lymphatic vessels it follows that in septic conditions, such as infected wounds, erysipelas, and abscess of the po.sterior portions of the scalp, the occipital and posterior auricular glands may become affected, and that in the same condition of the lateral part of the scalp the parotid lymphatic glands may become enlarged or inflamed, and septic matter from the frontal region of the scalp may eventually reach the submaxillary lymphatic glands. The course of the lympliatic vessels usually corresponds to that of the veins. Metastasis from carcinomatous growths generally follows the lymphatic vessels. In septic conditions or carcinomata of the anterior portion of the face, of the lips, of the tongue, and of the sublingual and submaxillary salivary glands the submaxillary lymphatic glands become enlarged. Similar affections of the outer part of the eyelids and face involve the parotid lymphatic glands ; and in corre- sponding conditions of the orbital, nasal, temporal, and zygomatic fossa?, of the deeper tissues of the cheek and of the roof of the mouth, the internal maxillary lymphatic glands may be affected. Before dissecting the neck, the student should remove the brain and place it in a solution to prepare it for dissection ; he should study the diploic veins, the dura mater and its processes, trace the meningeal vessels and the sinuses, and follow the cranial nerves to their respective foramina of exit from the cranial cavity. These structures and their dissection are described under the Membranes and ^''essels of the Brain. THE MEMBRANES AND VESSELS OF THE BBAIN. Dissection. — Before removing the calvaria, or skull cap, entire, its outer compact table should be removed on one side, so as to expose the diploe or middle table, with its bony channels for the accommodation of the diploic veins. This is most reae removed later, for if allowed to ri>niain in this solution for some time, it is more easily separated than in the fresh condition. If alcohol alone l)e used to pi-eserve the l)rain, the pia mater must be removed before placing it therein ; this is most readily done under water ; liut if preserved in alcohol and formaldchyd, the membrane may be removed at leisure. Brains hardened in ehlorid of zinc shovdd afterward be kept in alcohol. "When the brain has been removed from a subject injected (embalmed) with ehlorid of zinc, the pia mater can at once be separated and the brain placed in alcohol. If the brain from a fresh sulvject be immediately jilaeed in ale(.)hol, suljseqvient removal of the jna mater will l.)e foiuid almost imjiossible on account of its tlrm adherence. If the pia mater is not removed, the study of the convolutions is much less .satisfactory. Brains which have been hardened in ehlorid of zinc and afterward kept in alcohol are much easier to handle than when kept in zinc alone, as the latter, by its action on the skin, makes the fingers sticky. Brains preserved in alcoliol and formaldehyd are preferable to those preserved in a solution of zinc cldorid and alcohol, because they are not shrunken so much as the latter. Brains taken from a subject embalmed with zinc ehlorid should be hardened in a solution of the same ; only fresh brains should be hardened and preserved in alcohol and a two per cent, solution of formaldehyd. Processes of the dura mater. — The dura mater, through duplication of its inner or meningeal layer, sends three larger and five smaller partitions, folds, or processes into the cavity of the skull and between certain divisions of the brain ; these afford support to the latter. The three larger processes are the Jalx ecrcJiri, the tentorium ccrcbelli, and the falx ccrebelli. The five smaller processes or folds comprise two pairs and a single one. Of the two pairs, the larger are attached to the lesser wings of the sphenoid bone and project into tlie Sylvian fissure. The smaller pair, crescentic in shape, are attached to the clinoid processes and over- hang the optic nerves. The single fold of the smaller group stretches across the pituitary fossa covering the pituitary body, and is known as the diapln-afim of the pituitary fossa , or diaphragma sellx. Its center contains an opening for the passage of the infundibulum. 718 SURGICAL ANATOMY. The falx cerebri is a sickle-shaped process, narrowed almost to a point in front, where it is attached to the crista galli ; it is broad behind, where it is attached to the middle of the upper surface of the tentorium cerebelli. It projects into the great longitudinal fissure of the brain and separates the hemispheres of the cere- brum. Its convex upper border is attached upon' the inner surface of tlie calvaria to the edges of the groove which accommodates the superior longitudinal sinus. The concave lower border is free, arches over the corpus callosuni, and contains the inferior longitudinal sinus. The tentorium cerebelli is a somewhat triangular-shaped process, having its base attached upon the inner surface of the occipital bone to the edges of the groove for the lateral sinuses ; the sides are attached to the line of junction of tlie upj^er and posterior surfaces of the petrous portion of the temporal bone, from the apex of which they are continued to the posterior and anterior clinoid processes. The apex corresponds to the free edge, which forms the lateral and posterior boun- daries of the triangular opening known as the superior occipital foramen or superior foramen magnum. This foramen gives passage to the crura cerebri, the superior peduncles of the cerebellum, the oculo-motor and pathetic neiwes, and the basilar artery. The tentorium cerebelli projects into the great transverse fissure of the brain and sej^arates the posterior lobes of the cerebrum from the cerebellum. In the convex border of the base of the tentorium cerebelli the horizontal portions of the lateral sinuses are contained ; in the sides, the superior petrosal sinuses ; and in the middle, at its union witJi the falx cerebri, the straight sinus. The base of the falx cerebri is attached along the entire median line of the upper surface of the tentorium cerebelli, and the falx cerebelli to the median line of the lower surface. The tentorium serves to supjjort the posterior lobes of the cerebrum, thus protecting the cerebellum from pressure. The falx cerebelli is a small, vertical fold attached posteriorly to tlie internal occipital crest or inferior vertical limb of the occipital cross, and above to the under surface of the tentorium cerebelli ; it is situated between the hemispheres of the cerebellum. In its posterior border is contained the occipital sinus. This border at times splits into two parts, which are attached to the sides of the back part of the foramen magnum. Sinuses of the dura mater. — The sinuses of the dura mater are venous chan- nels formed l)y the separation of its endosteal and meningeal layers, and are lined by a prolongation of the lining membrane of the veins. They are rigid tubes, wliich always remain patent (Macewen) ; their function is to return the venous blond from the brain and its coverings, the diploe (with a few exceptions'), and al.so the greater part of the blood from the orbit and eyeball. They collect this blood and c(jiivey it to the jugular or posterior lacerated foramina, where it is taken THK MEMnjiAXES AXD VESSELS OF THE III: AFX. 719 up liy the intrrnal jufjular veins. There arc sixteen in all, and tiiey consist of two jjjroups : those situated at the uj)per and baelv part of tiic eranial ravity, and those situated at the base of tlie sicuU. The former grou[) includes tiie superior longitudinal, tlie inferior longitudinal, the straigiit, the lateral, and the occipital sinuses. Tiie last-named group iucludes the cavernous, the sinuses ahe parvie, the circular, the superior petrosal, the inferior jictrosal, and the transverse. They can also be divided into a median and a latei'al grouj), the former including the single sinuses, situated in the middle line of the skull, and the latter the paired sinuses, situated on both sides of the middle line. Five are in jjairs and six are single. The five pairs are the lateral, the superior petrosal, the inferior peti'osal, the cavernous, and the sinuses akc parv;e. The six single sinuses are the superior longitudinal, the inferior longitudinal, the circidnr, the transverse, the straight, and the occi})ital. Some anatomists describe the sigmoid portions of the lateral simises as an additional pair, thus making the number eighteen. The superior longitudinal sinus, which has already been expo.sed, occupies the convex border of the falx cerebri. It passes from the foramen cecum at the root of the frontal crest through the mesial groove on the inner surface of the cal- varia ; deviating slightly to the right in the piosterior part of its course, it runs to the internal occipital protuberance, to end in the torcular Heropliili. The torcular Hcfophili is the point of confluence of the superior longitudinal, lateral, straight, and occipital sinuses, and is situated a little to the right of the internal occipital protuberance. The superior longitudinal sinus is triangular on section, the base being directed toward the calvaria ; it is narrower in front, gradually increasing in width as it passes backward. Its lumen is crossed by a number of fibrous bands, the cliordie Willisii, and Pacchionian bodies are frequentlj' found projecting into it. It receives veins from the scalp through the parietal foramina, from the diploe, the dura mater, and the hemispheres of the cerebrum. These veins, particularly those from the cerebrum, — the superior cortical,— run into the sinus from behind forward in the direction opposite to that in which the blood current passes; furthermore, they pierce the wall of the sums veiy obliquely. In the fetus the sinus com- municates with the veins of the nose by a small emis.sary vein which passes through the foramen cecum, but this seldom occurs in the adult. The superior longitudinal sinus presents a variable number of lateral outgrowths or pouches, which have been named the lacunee laterales. It is into these that the Pacchi- onian bodies project. Wounds of, and line for, the superior longitudinal sinus. — The relation of the sinus to the skull renders it likely to be wounded in compound fracture of the vertex, and in trephining operations over the median line of the vertex. Hemor- rhage from this or any of the sinuses is best controlled by plugging with sterile 720 SURGICAL ANATOMY. gauze, unless the wound be small, in which case it can be closed by sutures. The course of the sinus is represented on the scalp liy a straight line drawn from the root of the nose over the median line of the vertex to the external occipital protuberance. Septic or infective processes of the scalp may enter the superior longitudinal sinus througli the parietal emissary veins ; septic processes of the nose may reach that sinus through the vein in wliich the sinus has its origin. Tlie lateral sinuses, the largest of the cranial sinuses, extend from the internal occipital protuberance to the jugular foramina, terminating at the begin- ning of the internal jugular veins. They arise on each side of the internal occipital protuberance, across which they are connected by a small branch ; thence they pass outward and forward, grooving the squamous portion of the occipital, the posterior inferior angle of the parietal, the mastoid portion of the temporal, and the jugular process of the occipital bone. Each sinus consists of two portions, a horizontal and a sigmoid. The horizontal portion is situated in the base of the tentorium cerebelli ; it is triangular on section, the base of the triangle being directed toward the occipital bone and the posterior inferior angle of the parietal bone. The sigmoid portion is situated below the tentorium cerebelli, and grooves the mastoid jiortion of the temporal and the jugular process of the occipital bone ; it is semicylindric on section, and is considered by some anatomists a separate sinus — the sigmoid. The superior petrosal sinus empties posteriorly into the sigmoid portion of the lateral sinus at its origin. The lateral sinus varies somewhat in size and position, a foct to be remembered in trephining operations. Tributaries of the lateral sinus. — The right lateral sinus is usually larger than the left ; it begins at the torcular Herophili, and is the continuation of the superior longitudinal sinus. The left lateral .sinus is the continuation of the straight sinus. In addition to the superior petrosal sinuses, the lateral sinuses receive emissary veins from the scalp, which pass through the mastoid and pos- terior condyloid foramina ; veins from the diploe (the occipital and the external parietal) ; the lateral inferior cerebral, and some of the superior and inferior cerebellar veins. Leeching. — A suitable site for applying leeches in meningitis is behind the ear ; in this way blood is extracted directly from the lateral sinus through the mastoid emissary vein, thus depleting the intra-cranial circulation. Another, but less favorable, location for the application of leeches in meningitis is near the inner canthus of the eye, where the angular vein anastomoses with the ophthalmic vein. Thrombosis of the lateral sinus. — The sigmoid portion of the lateral sinus, or the sigmoid sinus, is the portion of the intra-cranial venous circulation most con- PLATE CLXXVIl, ' Hariiantel^par ^Lafera/ sinus LINtS FOR SINUSES. 721 THE MEMBRANES AND VESSELS OF THE BRAIN. 723 cerneil in diseases of tlic miildle oar. Thrombosis of tliis portion of tlie sinus and of the commencenunit of the internal jugular vein constitutes one of the conipiiea- tidus y way of a tsnia 11 foramen placed external to that for the small superficial petrosal nerve, on its way to join the plexus of the sympathetic upon the middle meningeal artery. This nerve is seldom found in the dissection of the interior of the huse of the cranium, for in lifting up the endosteal layer of the dura mater the petrosal nerves are very aj>t to he severed unless the utmost care is ohserved. The Meningeal Arteries — the anterior, the middle, the small, and the Dsterior meningeal — run between the skull and the duia mater, and are apt to be destroyed, or at least cut, when removing tlie dura mater; notwithstanding this they can be traced by the grooves in the bones which they occupy. The greater part of the anterior branch of the middle and the terminal part of the posterior meningeal arteries have been observed when removing the calvaria. The middle meningeal artery. — The largest and most important of the meningeal arteries is the middle. As seen when dissecting the pterygo-maxillary region, both this and the small meningeal are branches of the internal maxillary artery. The middle meningeal artery runs between the two roots of the auriculo- temporal nerve and enters the cranial cavity by way of the foramen spinosum ; it occupies a groove in the greater wing of the sphenoid bone, and almost immediately divides into two branches, the anterior and the posterior. Small branches of the middle meningeal artery pierce the cranial bones and anastomose with the vessels of the scalp. The anterior branch runs through a groove across the great wing of the sphe- noid, and continues into another groove in the anterior inferior angle of the parietal bone. The commencement of this latter groove for a distance of one-fourth to one- half of an inch is often bridged over by a thin plate of bone, and is thus converted into a canal. The vessel continues along the groove near the anterior border of the parietal bone, runs almost parallel with the coronal suture to within a short distance of the superior longitudinal sinus, and gives off branches which run upward to the vertex and backward toward the occipital bone. The sinus alffi parvEe or spheno-parietal venous sinus at times accompanies the artery for a part of its course, and may conseciuently be injured in fracture or during the manipulations of the surgeon. The posterior branch, the smaller of the two, crosses the squamous portion uf the temporal bone along the line of junction of the scpiamous with the petrous por- tion, and tiien upon the posterior inferior angle of the parietal bone, where it divides into its branches. Extra-dural hemorrhage. — From the relation which the anterior branch of the middle meningeal artery holds to the anterior inferior angle of the parietal bone, it follows that fracture of this part of the skull is apt to result 734 SURGICAL ANATOMY. in hemorrhage, which would l;ie located between the bone and the dura mater. The vessel may be injured either by sharp bony spicula or by the sudden alteration in shape to which the skull is subjected in cases of severe head injury. It has already been noted that the dura mater is loosely attached to the vault of the cranium ; this accounts for the size of the large extra-dural blood-clots occasionally seen. From the relation of this l)ranch to the motor area of the brain it can readily be understood why the symptoms consequent ujion the pressure of an extra-dural clot are largel)^ if not altogether, motor. These cases constitute an especially favorable class for trephining, which should be done as soon as the diagnosis is made, or as early as possible. If upon the removal of the clot the bleeding has not ceased, the vessel should be tied. This may necessitate enlarging the original trephine opening in order to expose the bleeding points. The author has found it necessary to tie both the anterior and the posterior branch. It occasionally happens that the injury to the middle meningeal artery occurs on the opposite side to that upon which the external lesion exists. Point for trephining. — The point of election for applying the trephine in a suspected case of extra-dural hemorrhage, meningeal in origin, is at a point one and one-half inches behind and one inch above the external angular process of the frontal bone. When a simple or a compound depressed fracture is associated with the hemorrhage, the trephine should be applied near the fracture. To reach the posterior branch the trephine should be applied immediately below the parietal eminence, and on the same horizontal level as in the preceding operation. The opening can subsequently be enlarged in a downward or backward direction and the vessel thus brought into view. Branches of the middle meningeal artery. — The middle meningeal artery gives off branches within the cranial cavity to the Gasserian ganglion : a petrosal branch, which enters the hiatus Fallopii to supply the facial nerve and anasto- moses with the stylo-mastoid branch of the posterior am-icular artery ; a lacrymal branch which enters the orljit by way of the sphenoid fissui'e, or b\' a separate canal in the greater wing of the sphenoid bone, and anastomoses with the oph- thalmic artery ; a branch to the tensor tympani muscle ; and branches which leave the cranial cavity through foramina in the great wing of the si>henoid bone to anastomose in the tem]ioral fossa with the deep temporal arteries. It is accompanied by t^vo veins which ('mj)ty into the internal maxillary vein. The anterior meningeal arteries are branches of the ethmoid arteries ; they supply the dura mater of the anterior cranial fossa in the region of the median line. One of the arteria receptaculi, derived from the cavernous portion of the internal carotid artery, suj)plies the dura mater of the middle cranial Ibssa. It THE MEMBRANES AND VESSELS OF THE BRAIN. 735 anastomoses witli tlie niiddlo meningeal artery, and it also receives the name of anterior meningeal. The dura mater of the middle cranial fossa is supplied chiefly hy the small meningeal artery, a branch of the internal maxillary, which enters the cranial cavity by waj' cf the foramen ovale, and one or two branches from the ascending pharyngeal artery, which enter the cranial cavity through the middle lacerated foramen. The posterior meningeal arteries are the cranial branches of the ascending pharyngeal, the occipital, and the vertebral arteries; those arising frcun llic ascending pharyngeal and the occipital artery enter the cranial cavity by way of the posterior lacerated or jugular foramen, and those from the vertebral artery by way of the occipital foramen (foramen magnum) ; they supply the dura mater of the occipital or posterior cranial fossa. The ascending pharyngeal artery also sends a meningeal branch through the middle lacerated foramen, and an occasional one through the anterior condy- loid foramen. The meningeal veins, with the exception of those accompanying the middle meningeal artery, empty into the sinuses. INDEX. In this Imlex the references in heavy-face type are to the pages containing plates illustrating the subject namcil. Kelerences in regular type are to the text. A. Abducent n., 4(!.=i, 728, 539. IV'/e Sixth Cranial Nerve. Abscess beueatli temporal fascia, cerebellar, ■12.'? trephining. 511 cerebral, 42:! extradural, 12:5 trephiiiiiit;, ."ill intra<'ranial, .511 nia.stoiil, 420 of antrum of Highmore, 312 of cornea, 3li4 of face, 626 of frontal .sinus, 311 of laervnial sac, 644 of neek, 31, 47 of occipital trianj;le, 59 of pter\f;o-niaxiUary region, 692 ' of scalp, (il7 orbital, :52:5 parotid, 6."i7 i[icision for, 6.58 post-pharvMgcal, 2.32 t em i>or( (-sphenoid. .511 trephining, 511 Absence of iris, :!(is Acces-sory cartilages of nose, 293 qiiajlrate «irtilages, 293 Accommodation, 386 Acne, 2X5 Acroniio-thoracic a., 133 Adam's apple, 23 Adduction of cornea, 348 Air-chambeis of nose, accessory, 314 oritices, 298 Ala cinerea, 547, 536, 542, 556 AliC of nose, 2H4 Alei>ek, canal, 599 Alveolar a.. 684, 678 Am])iilla of semicircular canals, 4:!2, 439 Ampiillie of semicircular canals, 427 Amputation of tonsil, 225 Amygdala, 562. 560 Anastomosis of angular a. 644 of anterior temjioral a., 606 of cerebellar a., posterior in- ferior, 450 of cerebral a., 453 Anastomosis of cerebral a., ante- rior, 446 posterior, 453 of cerebral a.s, 453 of cervical a., ascending, 145 dee]), 147 of coronary a., (i43 inl'i'rior, 643 sui)erior, 643 of facial a., 648 transverse, 644 of frontal a., :i37, 606 of inferior coronary a., 643 labial a., 643 of infra-orl)ital a., 676 of lateralis nasi a., 644 of lingual a., Ill of mental a., (i76 of nasitl a., 'S'.i"! of oecipitjil a., 006 of posterior auricular a., 606 temporal a., 606 of princeps cervieis a., 95 of ranine a., 114 of scapular a., posterior, 146 of sul)lingual a., 115 of superior coronary a., 643 . of supra-orbital a., 336, 60,5 of thyroid a., inferior, 144 of transverse facial a., 641 Ander.sch. ganglion, 116 Anesthesia of cornea, 379 temporal a. in, 606 Anenrvsm, cirsoid, 606, 599 Angle,' filtration, :!91, 394 of chamber of eve, anterior, :{91 Angles of mouth, 210 AngtUara., 6:!-', 611, 608, 613, 640 anastomosis, 644 convolution, 486, 489, 474, 477 gyrus. 489, J'ide Angular Convolution, vein, 35, 645 Aniridia, :!68 Anneetant gyri, 4-^5 Annular synechia, 394 posterior, :!95 Annulus tympanicus, 403 Anosmia, 302 Ansa hypoglossi nerve, 66, 73, 71 737 Ansa Vieussenii, 85 Anterior chamber of eyeball. 17r/c Chamber of llyebali. Anterior. Antero-lateral fontanel, 5''1 Antlielix. I'iil< .Xntilic lix. Antihelix, 399, (Kill. 398. 661 fo.ssii, ;!99, 6611, 398, 661 Antitragicus in,. 401, 663, 665 Antitragns, 399, 660, 398, 661 Antrum, mastoid, 412, 413 freiihining, 415 of Highmore, 312, 339, 350 absces.s. 312 cj-sts, 315 dropsy, 315 empyema. 313 Uiucnet4e, :',12 oriliee, 298 ttnnors, 312 Anvil, 423. Vidi' Incus. Aorta, 129, 133, 137 Aperture of laiyii.\, 218 superior, 2:.i7. 247, 250 Apex of lung, 18 Aphasia, .50:! Aponeurosis, palatine, 246. 242 of occipito-frfintalis m,. 615, 599, 627 jihary lineal, 2:;i, 229, 243 suiira-byoid, 98 Apoplexy, (liinger, 454 internal capsule, 548 Apparatus, laervnial, 351, 350, 355 Appendages of eye, 648 Aqueduct of Svlvius, 537, 483, 516, 528 529 Ai)ue(lmtiis c'nebli-,'1, 434, 436 oriliee, 430 vestibuli. 431 orifice, 430 A(pieoiis bunior. :!92 Aracluioid. 4:!S inembranc' of brain. 709 removal, -i'.)-* Arantius, ventricle. 54 1 Arbor vita;, 567, 516 Arch, supra-orbital. 593 zygoniatie, .596 fracture, .586 Arches, branehi.il, 25 visceral, 25 Arciform fibers, superficial, .554 Arcus senilis, 364 738 INDEX. Area, dangerous, of eye, 368 of muscular seuse in brain, 500 of tactile sensation in brain, 500 Areas of brain, motor, 499, 501 sensori-motor, 500 sensory, 499, 501 Areolar tissue of eyelids, 652 of scalp, (>16 Argyll Robertson i)ui)il, 367 Arnold's ganglion, 691 nerve, 81 Arteria aberrans, 1 47 comes nervi plirenici, 66 septum nariuni, (!4.'5 Arterioe receptaculi, 7"-'9 Arterial blood in facial vein, 047 Arteries at base of brain, 452 carotid, 23 branches, 87 diagram, 87 cerebral, anastomosis, 453 ciliary, 336, 379 of bniin, 445, 444 of ear, 665 of face, 640, 596, 608, 613 of larynx, 263 of neck, ligation, 160 of orbit, 334 of scalp, 640, 5SS, (!05, 608, 613 of septum of nose, 6 1:1. 608, 613. 640 hemorrliage from, 643 of thyroid gland, 126 of tongue, 105 of tonsil, 105 subclavian, differences be- tween, 128 to brain, jieculiarities, 453 Artery, acromio-thoraeic, 133 alveolar, O-' 1, 678 angular. ()3s, 643, 608, 613, 640 anastomosis. 6 13 anterioramicnlar. 608, 613, 620, 640 deepfi-mporal, 683,678, 682, 686 dental, 676 meningeal, 734 superior dental, li-'l. 686 temporal. 606,603,608, 613, 640 anastomosis, 606 aorta, 129, 133 ascendini; eer\ical, 78, 79 frontal. 447 ])arietal. 447 ]iharyngeal. 105 auditory, internal, 450 aiuicnlar, 95 anterior. (it)6, 608, 613, 620, 640 anastomosis. (I0(! :',t, liiui asciMiiliiifi, 447 iiilVrii)r, 447 of aiiU'iiiir ctliiiioiil. ;i:57 gaiifc' ionic. Miitcro - lateral, 444 antiTD-iMcdiaii, 444 postciK-iiu'diaii. 444 gingival, 682, 695 hyaldicl, ;i^<.") Iiyi)iil. -^li incisive, i\<'<. 682 iufeiior ciii'iiiKii V, of li|i. iH'.i, 608. 613. 640 anastomosis, (i 1:1 conrsc. (ill! dental. li-^:5, 678, 682, 686. 695 laliial. (!l:!. 608. 613, 640 ana.stoniosis. i>K> intra-bvoid. iiTcgularities. 16G ligation, ICIO, Ifi.i collateral circnlar tion. l(j.'> line for. 20 operation to e.\|)o.sp, 164 pnlsations, is relations. IG.i intercostal. 133 first, H7 superior, 147, 133, 137 internal carotid, 7^9, 715 course, 7'3!) niaxlllaiv. UTH. u-n. G20, 621. 678 682, 686. 695 liranclies, ^i<^ divisions, (W:! jiterygoid, 6^1. 682 labial, inferior, 608. 613, 640. 682 ana.stoniosis. 1!4:? lacrymal, :?2:?, :5:5(i, 334 branches, 330 laryngeal, inferior, 1 1.">. 'Ko, 263 of inferior thyroid. 1 1.") superior. 'Jl, ii'<'>. 50, 70 78, 123, 251, 263 lateral nasal, 613 lateralis nasi, 64 1 anastomosis, 04 1 lenticnlo-striate, 1 Hi lingual, !il, 11 1. 50 70, 78, 79. 105, 133, 177 anastomosis, 114 irregularities. 190 ligation. 04. l-^-*, 177 line for. 20, 67 operation to expose. 183 Artery, lingual, relations, 02 malar, of lacrymal, 330 maniniar\, inlernal, 1 10, 78, 79, 129, 133 ma.sseieric, 0-1, 621, 678, 682 mastoid, 'Xk 90 ma.\illar\'. interna]. 0"!i. (1-0, 0S3. 133. 620. 621. 678. 682. 686. 695 meningeal, anterior, 734 middle, .'>:i-.'. li-:".. 7:r,, 303 682. 686. 690. 695. 709, 714. 715 laanelies, 733, 731 uound, 734 of anterior ethmoid, 337 ofascending jiharvngeal, 97 posterior, O.'), 449, 73.5, 444, small. 0-^3, 73,"., 682, 686. 695 mental, 070, (;-3, 620. 682, 695 anastomosis, 070 middle meninL;eal. .'i9'.'. 733, 682 686. 690. 695. 709. 714. 715 j branches. 733. 734 wound. 731 superior dental. 695 temporal. 608. 613, i 620, 640 mvlo-livoiil, 1(1 1. 0-:;, 682, 686. 695 nasal. 3;!7, 682 ana.stoniosis. .337 lateral, 613 of anterior ethmoid, 337 naso- palatine, (\m occipital. 9:'.. OdO. 50. 70. 133. 603, 608, 613 640 anastomosis, 00(> branches, 94 irregularities, I9o ligation, 91, 19;') operation to exi>. 229, 334, 444, 715 branches. 33.") niuscnlar. 337 orbital, 608, 640, 682 palatine, a^eeuding, !>'-' deseenditiu, 307, 084, 105. 682 of ascending pharyngeal, 97 palpebral. 682 inferior. 337 of lacrymal, 336 of .supraorbital, .336 superior, 3:!7 pariettil, .i.scending, 447 Artery, parieto-teinporal, 447 parotid, of posterior auricu- lar, 9(i perineal, of female, trans- vi'l'se. ■Hu jieriostetd, of sniiraorbital, 3:'>0 pharyngeal, ascending, 97, 70, 78, 79, 105, 229 relations, 97 of ascending pharyngeal, 97 posterior auricular. OtUi. 603, 608, 613, 620, 640,678 ttnastomosis, ()(Ki dee]) temporal, 0^3, 678, 682 dental, 084, 682 meningeal, .599 temiioral. 000, 603, 608, 613, 640 aiuistomosis, 000 prcvcrlebiiil, of aseeuding pharyngeal, 97 princeps cervicis, 95, 133, 137 anastomosis, 95 profunda cervicis, 174, 133, 137. Vide Deep Cervical .\rterv. pterygoid, 678 'external, 0-4, 682 internal, 0-4, 682 ptervgo-palatine. 0-1, 682 rani'ne, 9-J, 114, 105, 221 anasttimosis, 114 recurrent, of lacrymal, 330 retinal. 381 scapular. ]iosterior. .59, 146, 70. 133 anastomosis. 140 small meningeal, 083, 735, 686. 695 splieiHi palatine. 307. fiS4, 682 spinal, anterior. 449. 444, 452 liitcral, of vertebra', 1 13 ])osterior, 449, 444 sterno-mtistoid, inferior. 1 10, . 70. 78 mi. idle. .-.-. 91. 50. 70. 78. 177 superior. 9.5. 70. 78 stvlo-mastoid. 90 siibdaviaii. •.':'.. 00, l-.'7. 100, 50 70, 78,79, 133, 208 branclies, l:!0, 87 coiii]iressioii. :-'!'< di.igrani, 87 first iiortion. 129, 164, 174 ligation. 13,"i, 10(i irregularities. 170 left. 12S relations. 128 ligation, collateral oircn- laliou. i:r,, 133 line for, 20, 67 740 INDEX. Artery, subclavian, right, 127 relations. 127 second portion, 131 ligation, 135, 100 relations, 131 third jjortion, 131 guide, 17.5 ligation, 132, 160, 169 ligation, colla- teral circula- tion, 170 operation to ex- pose, 167 relations, 131, 160 variations, 133 sublingual, 115, 78. 79, 105 ana.stomosis, 115 SHbiuaxillarv, 93 sulmicntal. 93, 50, 70, 105, 682 relations, 93 subscapular, 133 superficial cervical, 70 temporal, 620, 621, 640, 678. 682, 686 superior cuiciiiaiy. ot'lip. (i43, 608, 613, 640 anas to niosis, 643 supra-acromial, of s u p r a- scapular, 146 supra orliital, 336, 605, 197, 334, 603. 608, 613, 620. 640 anastomosis, 336, 605 branches, 336 operation to expose, 197 supra-scapuhir, 0(1, 145, 50, 70, 78,79,129,133, 174 branche.s 146 relations, 145 Sylvian, 446 temporal, (iOO. 193, 621 anterior, lidO, 603, 608, 613, 640 anastomosis, 006 deep, 0S3,678,682, 686 in anesthesia, 606 middle, 608, 613, 620, 640 oiieration to expose, 193 po.sterioi-. 000. 603, 613, 640, 686 anastomosis, ()(.)(J deep, Om:;, 678, 682 supeitirial, 133, 620, 621, 640. 678, 682, 686 ligation, 195 thoracic, long, 133 sii]MMior, 133 thyroid axis, 1 11, 78, 79. 174 inferior, 01, 1 11. 20,78, 119, 133, 174, 177, 229 anastomosis, 1 14 J yroid, inferior, bran- ches, 1 14 irregularities, 179 ligation, 145, 179, 177 line for, 67 operation to expose, 174 superior, HO, 20, 50, 70, 78, 105, 123, 133, 177, 251 irregularities, 1h,k ligation, 187, 177 line for, 67 operation to expose, 183 thyroidea; ima, 126, 133 tonsillar, 93 of facial, 105 of dorsalis lingua', 105 tracheal, of inferior thyroid, 145 transversalis colli, 59, 60, 146. 50.70,78, 129, 133, 174, 208 humeri, 145 transverse, facial, 644, 608, 613. 620, 640, 678 anastomosis, 644 transverse, of basilar, 450, 444. 452 trochlear, of snpra-( irl li tal . 3:!6 tympanic, 0s3. 682, 686 of ascending pliarvngeal, 97 vas aberrans, 133 vertebral, 01, 130, 449, 39, 70, 78, 79, 129, 133, 137, 152, 164, 174, 444, 452 branches, 143 cervical jiortion, 136 guide. 176 irregularities, 176 ligation, 143, 175 occipital portion, 143 operation to expose, 174 relations, 136, 175 vertebral portion, 136 Vidian, 684, 682 Articulation, crico-arytenoid, 276 ligaments, 270 crico-thyroid, 270. 263 moveinent,s, 270 of head, 573 of larnyx, 276 of neck, 573, 579 of .skull, 573 temporo-maxillary, 573, 576, 577 blood-supjily, 574 inter-articular fibro-car- tiiage, 574 ligaments, 573 internal lateral, 574 movements, 574 nerve supply, 574 .synovial membiaiie, 574 Artificial mcmlirana tymi)ani, 420 Arvtcno-c]iiglotti(lc,in folds, 24si, 212 218,236,250,258, 259 Aryteno-epiglottidean muscle, 201, 258, 259, 263 action, 202 insertion, 261 nerve supply, 262 origin, 261 Arytenoid cartilage, 275, 267, 271 Arvtenoideus m., 256, 258, 259, 263 action, 261 insertion, 956 nerve su])ply, 256 origin, 2,56 Ary-vocalis of Ludwig, 20] Ascending cervical a., 78, 79 pharyngeal a., 105 Aspiration (jf snliarachuoid spaxie, 442 Asterion, 591 , 506 Asthma, laryngeal, 262 Astigmatism, 303 Atrium of meatus of nose, 299 Atro])hy of testicle, 648 of tongue, 220 Attachments of dura mater of brain, 711 Attic, 407, 405, 409, 422 Attolens auiim m., 005, 627 action, 005 insertion, 605 ner\ e supply, 605 origin, 605 Attrahens aurem m., 605, 627 action, 605 insertion, 605 nerve supply, 605 origin, 605 Auditory a., internal, 450 canal, external, 403. Mde Auditory Meatus. meatus, external, 403, 405, 409 blood supply, 404 lymphatics, 407 nerve supply, 407 occlusion, 404 relations, 404 sinus, 403 veins, 407 nerve, 438, 405, 729, 539. ]'Ule Eighth Cranial Nerve, ossicles, 423 striae, 547 Aural vertigo, 437 Auricle, 660, 661 cartilage, 400 intcgmnent, 400 landmarks, 660 muscles, intrinsic, 400 supernumerary, 400 Auricnlar a., 95 anterior, 606, 608, 613, 620, 640 anastomosis, 600 deep, 0^^;'., 682 posterior, 90, 01)0, 50,70, 71. 78, 79, 203, 603, 608, 613, 620, 640.678 anastomosis, 606 branches, 96 relations. 96 L\ni:x. 741 Auricular Iiraiicli -!■< Sitat. 30, 609 IMisteriiir, 117. lil'-', 51. 70, 71, 78, 79, 203 region, ilisseetioii. (!UII vein, posterior, "Ki, 35, 50, 51, 70, 645 Anrieularis iiiamiii-i ii,, 32, 38, 34, 51 Iiraiu-lies. 38 relations, 20f> iVnriculoteinporal n., 20."), (!12, (W<, 193, 303, 609, 613, 620, 686, -678, 690, 695 ili\ isions, 038 operation to exiJOse, 2ir>, 193 Axillaiy a., 133 nerve jilexiis. 14^. J'ide Bra- cliial Xerve I'lexus. Axis of evelnill, 357 Az\>;os u'vuhe m., 24(i, 242, 243 aetion, 246 insertion, 246 origin, 246 Eanil, furrowed, of cerebellum, 562 liorn.v, 526 Bartholin, dnct, 1 14 Base of brain, 458 arteries, 452 structures. 456 of no.se, 2s!4 of skull, dislocation, 579 fracture, 5.s.-,, (;;)2 Basilar a., 449, 551), 137, 444, 452 branches, 450 plexus, 714 Bichat, fissure, 467. 533 Bifurcation of inuoininate a., 70 Bimanual examination of female, (i(>2 Bisentral lol)e of cerebellum, 560 Blaiidin, uland, 219 Blindness, word-, 503 Bodv, ciliarv, 368 geniculate, 538 external, 538, 463. 539, 552 intcriKil. 5:is, 463. 539. 542, 552, 556. 560 of coqjus callosum. 516 of fornix, 522, 533. 546 of lateral ventricle, 518, 519, 529, 569 olivary, 554, 458. 539. 552 corpus deiitatum, 554 pe7 libel's, conniii.S'^ural, longitu- dinal, 0-I9 transverse, 549 peduMcnlar, ,548 fissures, 4(i-<. ]'i9 ])rimary, 470 interior, dissection, .")12 lobes, 469. I'iile Lobes of Brain, lower level. 507 peduncles, 4lilt. ,">.")0 position, 4.">.5 section, horizontal. 513 transverse, 546 surface anatfiniv. lH-i inferior. 4i38. 497 internal, ,510 median, 488. 497 veins. 454 white matter, 518 Cervical a., ascendin^i, 144, 70. 78. 79. 133 anastomosis, 145 deep. 147 anastomosis, 147 .superficial, .59, 146, 70, 133 transverse, 59. I'itle Transver.s;ilis Colli .\rter.v. fascia, deep, 45 course, 46 diagram, 41 flstuliE, congenital, 25 ganglion of sym|)athetic, in- ferior, ~i5 middle, S4 superior, •^4 lymphatic glan5, 519, 523 Corrugator ,suiKTcilii in., ti:i4, 346, 632 action, liHI insiTlioii, (iiil lu-rvi' siipplv, 6:!4 orifjiii, (>:i4 Corte.K of cerebrum, disease, 504 of lens, 391 Corti, organ, 437 Cranial n., eighth, 465, 458, 542, 556. Vide .•\uilit(irv Nerve, origin. 552 eleventli. 57, lU(i, 458, 542. 556 origin. 552 fifth, 465, 326. 339, 458. 542. 556 oplitlialinic division, 326 origin. 552 first. 461. ('('(/<■ Olfactory Nerve, fourth, 327, 462, 326, 339, 343. 458, 542, 556. 560. 1 7(/<' P a t li e t i c Nerve, origin, 552 recurrent lira uc h, 326 ninth, 466, 458, 542, 556 origin, 552 second, 462, I7i/(i)ptie Nerve, seventh, 465, 458 origin, 552 sixth, :!ll, 4ti5, 326, 339, 458, Vith- Ab- ducent Nerve, tenth, 76, 466, 458, 542. 556 oriiiin. 552 third. :!ll, 462, 326, 458. Vide Oculo- motor Nerve, origin. 552 twelfth, 101, 467, 458 origin, 552 nerves, origin, 452, 715 superficial origin, 458 Craniectomy, 512 Cranio-eerebral topography, 499 Cranium, bones of, 5HS landmarks, .5^'7, 589 Crescentic lobule of cerebellum, anterior, 560 posterior, 560 Crico-arytenoid articulation, 276 S— 48 Crico-arytenoid articulation, lig- aments, 276 ligament, posterior, 276 transvei-se, 276 muscle, posterior, 263 Crico-arytenoideus lateralis m., 261, 259 action, 2(il insertion, 2(il nerve supply, 2(il origin, 2(il posticus nuiscle, 256, 258, 259 action, 256 insertion, 256 nerve sujjply, 256 origin, 2,">(! Cricoid cartilage, 24, 274, 123, 251, 254. 258. 259. 263, 271 ossification, 271 Crico-thvroid a., 91, 78, 123, 251 articulation, 267, 263 nu)venients, 276 meinbraiic, 24, 255, 123, 251, 254 muscle, 2.55. 123, 251 action, 255 insertion, 255 nerve supply, 255 origin, 25,5 space, 24 Crista (ialli, 715 vestibuli, 431 Crura cerebri, 160, 5,50 of stajies, 424 Crural monoplegia, .504 Crus cerebri. 460, 5.50, 458. 483. 494. 516. 539, 542, 552, 556 crusta, .553, 488, 497 tegmentum, 553, 488, 497 nuclei, .5.53 Crusta of crus cerebri, 460, 553, 488, 497 Crypts of iris, 392 of tonsils, 224 Crystalline lens, 386, 360, 372, 394. Vi,h' Lens, relations, 386 Culraen, 560 of monticulus cerebelli, 561 Cnneate nucleus, 557 tubercle, .557 Cuneiform cjiitilage, 274, 218, 236, 250, 271 Cuneus, 491, 488, 494, 497, 516 Cupola of cochlea, i:!.', 427, 434 Cutaneous n., internal, 149 lesser internal, 149 of perineum, male, 603 C.yclon, 368 Cyst, branchial, 26 dermoid, of pinna, 400 seb.aceous, of pinna, 400 Cystotomy, median perineal, 622 Cysts of antrum of Highmore, "315 Darwin's tubcrcde, 399, 398, 401, 527 Deafness, 424 word-, 503 Declive. .561. 560. Vide Clivus. Decussjiiiiin of iiyramids, 553, .554, 458, 552 Deiters' nucleus, 165 Density of temporal fa.si^ia, 618 Dental a., anterior, 682 su))erior, 684, 695 inl'eridi-, 6s:!, 678, 682, 686, 695 middle superior, 695 po.sterior, 6- of inferior maxilla, 5>l.v, 655 veins, 655 Face, absces.s, 626 appearance, 592 arteries, 596, 608, 613, 640 boiu-s, fracture, 586 dissection, 625 incision, 597, 623 fascia, snperfieial, 6'.'6 incision for dissecting, 597, 623 landni.'U'ks, 592 l,vm])liatics, 703 liiuscles, 626, 613, 627 nerves, 691, 609, 613, 620 skin, 625 surface markings, 592 va.scularity, 617 veins, 35! 645 vvonnds, (i 17 Facial a., 9-.'. 63-*, 50. 70. 78. 79. 105. 133. 608, 613. 620. 621, 640 anastomosis, 648 branches. 6-13 cervical jiortion. 92 l)ranches, 92 course, ().38 irregularities, 190 ligation, 190 line for, 20, 27, 67, 623 o]ieration to expose, 182, 183 relations, 638 transverse, 61 1. 608, 613. 620, 640, 678 anastomosis, 644 expression. 596 monoplegia. .504 nerve, li;5, 666, 7--'-<. 51. 71, 78. 79, 203 539, 620, 621. 1 7(/c Sev- enth f'ranial Xerve. anricularis magnus, 38 branches, 666 Facial uerve, huccnl branch, 669, 609. 613, 620 eoui'se, (!66 digastric branch, 669 divisions of. facial, (>66 intra-cranial, Ii66 teiniioral, 6<)6 iuframaxillarv branch, 34, 620 infra orbital b r a n c h , 609, 613, 620 line for, 20, 27, 67 malar braiieh, 609, 613. 620 operation to expose, 666, 203 paral,\sis, 670 stretcliing, 2(15 st,vlo-liyoill. 516, 528, 529. 560 111).)!-, 536 Fovea centralis, :!■<() infirior, .">1T liciniolliplicn. 1:M, 430 lirmispli.ii.-.i, I:>1, 430 su|it'ii(>r, .") 17 Fractuie into frontal sinns, :?11 of lioni's of fact". .)^() of liyoiil lioiie, ■J.'^l of iiilVrior maxilla. .">■<(>, 581 of lanvMial bono. ,58(> of na.sal liont's, "JSli, 586 of skull, 584 base, 58,5 vault. 585 of supciior maxilla, .586 of tliyroiil i-artilajic '274 of zy^omatif arch, .5'<6 Fractures, c-ompouud, of skull, 707 of skull, base, 692 Fnenuin epi^lottidis, 316 labii inferioris, 210 superioris, 210 Frenulum, 541! veli, 560 Frenuni of tongue, 215 artery, 115, 105 Frontal a., :«7, 60(;, 603, 608, 613, 620, 640 anastiouiosis, 31!7, 600 a.scending, 447 inferior, 447 bone, .sinuses, 591 branch of anterior ethmoid a., H:!7 convolution, ascending, 482, 474, 477, 480 inferior, 482. 474, 477, 480 middle. 482. 474, 477, 480 superior, 482, 474, 477, 480 diploic v., 707, 705 eminences, 591 fissure, inferior, 4-*!, 474, 477, 480 line, 50^, 506 superior. 4-38. Viih- Ganglion, Lenticular, branches, 341 Ga-sserian, 730, 326. 339, 695, 715 brauclies, 730 relations, 730 to cavernous sinus, 725 renuival, 731 resection, 199 intercarotid. 7(i jugular, IKi lenticular, 338, 326, 339, I 'iili- (iangi ion, Ci I iary . sensorv root. :'>35 Jleckel's, '697, 303, 686, 690 of Andersch, 116 of synipathetic cervical, in- ferior. 85 middle. 84 sn]>erior. 84 ophthalmic. :i38 otic, (i91, 303, 690 petrous. 116 s|iheno-])alatiiie, 697 submaxilhiry, 113 Ganglionica., antero-lateral, 444 antero-niedian, 444 poslero-median, 444 Gangrene of pinna. 400 Gas-serian yilu^lion. 7:')0. 326, 339. 695, 715 branches, 730 relations. 730 to cavernous sinna, 725 removal. 731 resection. 199 Geniculate liodies, 538 Geniculate bodies, external, 538 internal, ,538 body, external. 463, 539, 552 internal, 463,539,542, 552, 556. 560 Gcnio-hvo ;;lo>sii-! m., 111. 220, 78. 79, 105, 109, 212, 296 action, 1 1 1 blood snppl\ ,111 insertion, 1 1 1 nerve supply, 111 origin, 1 1 1 relations, 1 1 1 Geuio-hvoid m., 1(17. 78, 79, 105, 109, 212, 296 action, llH blood sn]i|)ly, 107 insertion. 107 nerve supjily, 107 origin, 107 Genu of corpus callosum, 517, 488, 497, 516 523, 564 Gingival a.. 682, 695 Glabella, .507, 5,S8. ,-,94, 506 Gland, lacrvmal, 653 parotid', 656, 608, 613, 627, 640 contents, 657 lobe, carotid, 6.56 glenoid. 6,56 jitcrygoid, (!56 removal, (i58 sensorv nerves, 657 woiMids, 6.58 Glands, auricular, posterior, 157 buccal, 213. 638 cervical, deep, 157 superlicial, iw. 157 infraclavicular, 157 labial, 21(» lacrvmal, 323. 328, 326, 330. 334, 339, 355 inferior-, 32*-< sui)erior, 328 sus])ensoiy ligament, 328 lymphatic, auricular, poste- rior, 7(r2 buccal, 702 lingual, 703 ma.stoid. 702 nuixillary, internal, 703 occijiital, 702 of head, 702 parotid. 657, 702 posterior pharyngeal. 703 submaxillary, 702 sub(n-cipital, 702 Meibomian, 5ii3, 652, 346, 355, 632. 653 duct, 353 ducts, (!ls orilice, 653 molar, 213 mucous, of Eustachian tube, 411 of larynx, 260 of nose, 302 occipital. 157 of Blandiu. 219 of carotid sheath. 73 of neck, 159, 157 750 IXDKX. Glands of Nuhn. 219 of tongue, 219 parotid, 63, 157 pineal, 539. Vide Body, Pineal, sebaceous, of oilium, 353 sublingual, 113 blood supply, 114 nerve supply, 11-1 relations, 113 submaxillarv, 63, 103, 113, 51, 157, 177 relations, U)3 sweat, of Moll, 353 thyroid, 23, 122, 123, 129, 251 arteries, 126 capsule, 126 in tracheotomy, 122 isthmus, 251 nerves, 126 relations, 122 structure, 122 Waldeyer's, 353 Glaucoma, 395 pa4n, 362 Glosso-epiglottidean fold, 216, 218 lateral, 216, 250 median, 216, 250 ligament, 270 pouch, 216 valleculfE, 216 Glosso-pharvngeal n., 115, 116, 466,729,79,539. Tide Ninth Cranial Nerve, relations, 116 tympanic liranch, 426 Glottis, edema of, 269 false, 266 respiratoria, 266 vooalis, 266 Goitre. ]lde Thyroid Gland. Gracile nucleus, 557 Gracilis funiculus, 557 Great horizontal tissure of cerebel- lum, 2(!1 Groove, lacrymal, 317 Guide to subclavian a., third portion, 175 to vertebral a., 176 Gum boil, 214 (Jums, the, 214 Gustatory n., 112, 688 Gyri, 468. Vide Convolutions, annectant, 4.85 operti, of island of Reil, 471 Gyrus, angular, 4h9 fornicatus, 499, 488, 497, 516 rectus, 4S2, 483, 488, 497 H. Hammer, 423. Vide Malleus. Handle of malleus, 418, 422 Harelip, 21:;, 614 operation, 210, 213, 644 hemorrhage in, 644 Head, arteries, 573 lymphatic glands, 702 nerx'cs, operations, 196 of caudati- niicU-ns, 536 Head of malleus, 422 veins, 665 Headache, trephining, 512 Hearing, center, 5(i:! organ, 399 Helicis major m., 66.-), 401. 663 minor m., 665, 401, 663 Helicotrema, 432 Helix, 399, 660, 398, 401. 661, 663 fissure, 40(1, (i66 fossil, 399, (iCO. 398, 661 Hematoma of scalji, 617 Hemianopsia, 4()2, 5U4 Hemiplegia, 504 crossed, 550 Hemispheres of cerebellum, 461 Hemorrhage, cerebral, a. of, 446 extra-M) into pterygo-maxillary re- gion, 692 subconjunctival, 358 Herpes cervico-occipitalis, 45 labial i.s, 210 Hiatus semilunari.s, 209, 298, 314 Highmore, antrum of, 312, 339. 350 abscess, 312 cysts, 315 dropsy, 315 empyema, 312 mucocele, 312 oritice, 298 tumors, 312 Hippoc,am|iaI convolution, 495, 488, 494, 497 fissure, 4!m;, 488, 494, 497, 536, 569 j)ia mater, 546 Hippocampus nuijor. 19('>. 526, 519, 523, 529, 536, 546 minor, 191. 521, 531, 519, 523, 529 His, canal, 125 Horizontal division of lateral siuns, 720 fissure of brain, 467 Horner's ni., 633. Vide Tensor Tarsi Muscle. Horny band, 526 Huguier, canal, 691 Huuu)r, ai|Ueous, ,392 Hutchinson, test teeth of, 214 Hvaloid artery, 385 canal, Ssii, 392 membrane, i!i^5 Hydrocephalus, internal, 442 Hyo-epiglottidean ligauu-nt, 270 Hvo-glossusm., lOS. 220, 78, 79, 105, 109. 177 action, 10>< blood supply, 108 insertion, lO.'^ nerve suiiply, 108 origin, 108 " relation, 108 Hyoid a., 86 bone, 23, 281, 109, 123 fracture, 2isl Hypermetroi>ia, 3(i3, 373, 395 Hy])eropia, 395 Hyiieropic eye. 389 llvpertrophy of iiliarvngial tonsil, 232 Hypo-glossal fissure, 554 membrane, 21(i, 220, 270 nerve, 104, 112, 177, 467, .554, 729, 51, 71, 78, 79,539. 1 7^6, 50, 70 vein, 117 Infra-marginal convolution, 462 Infra-maxillary branch of cer\ ico- facial n. , 45 of facial n., 670, 34,620 Infra-orbital arterv. 67(i, (;s-l,620, 678, 682, 686, 695 anastomosis, ('<',(', branch of lai-ial n., (;69. 609, 613. 620 foramen, 595, (;!)9 margin, 316, ,594 nerve, 675, 697, 609, 620, 695 liranches, 675. Cl'T labial, <::.">, 620 L\DEX. 751 Infra-orbital iiervo, hranolips, nasal, (!*."), 620 l>aliu-l)ial, 1)75, 620 openitiiiii to oxpose, (i!)!! stnii'tinv iiivolvt'il, ()!l!) resection, 19!) plexns of nerves, (jG9, 675 vein, (>~(> Infnirimal imrtionof larvnx, 296 Inlra-tr(M-liKar n., :!3.'i, 326, 609, 613. 620 Infiindihiilifonn fa.scia, (il3 Infiindlliiiliiiii. 539 Inion, .■)lll, 506 Injinies of ni'cU, '^\ Innominate a., 78, 129. 133, 164 bifuiciition, 70. 78 guide, Kill irreaularities, l(i6 lig-.vtion, KiO, 1(J5 collateral circula- tion, lG,j line, 20 operation to exix)se, 164 puls;itions. 18 relations. Icio vein, 35, 645 left, 129 ri-lit. 129 Internment of anriele, 400 Interartienlar til iro-cartilage of temporo-niaxillary articnlation, 574 Interarvtenoid fold, 218, 236, 250 ganglion, 71! Intercostal a., 133 tirst, 147 superior, 147, 133, 137 nerve, first. 149 Intercrnral space, 459 Internal e^Tpsule, 547, 565, 569 genu, 548 liemorrliage. 548 limli. .-mterior, 547, 546 posterior, 547, 546 ear, :5nii, 4:U blood supply, 437 lymphatics, 438 veins, 437 lateral ligament of temporo- maxillary articulation, 574 maxillary v., 35 Interpeduncular space, 459 Intei'stitial keratitis, 3(32, 363 Intersutural membrane, 1117 Intervaginal lymjih space, 395 Intra-cranial abscess, 511 division of facial n., 666 nerves. 727 coni-se. 727 neurectomy of inferior maxil- lary n.. 730 of superior maxillary n., 730 Intraparietal fissure, 485, 474, 477. 480 line. 509 Intrinsic ni.'s of pinna, 40O, 401, 663 Irido-cyclitis, 374 Iris, the, .iiC. 360, 365. 369, 376. 394 absence, 31)8 blood supply, 368 (•left, 368 color, 367 crypts, 392 lymi)h spaces, 392 nerve supply, 368 jiectinatc ligament, 364 rellex, 368 Irregularities of carotid a., inter- nal. 196 of occipital a., 195 IrritJition of laryngeal n., supe- rioi", >'2 of lingual n., 223 Island of Keil, 470, 481, .548, 471, 483, 546, 565, 569 gvri (iiiirti. 471 Isthmus, ino. 488. 494. 497 of ra\K-rs. -.'i:;, 221, 237 (if thvn)id gland, 251 tnb;c. 411 Iter chord:e anterius, 691 posterins, 412 e tertio ad ciuartum vcntric- ulum, 51s, .537. Vide Aque- duct of Svlvius. Jack.sonian cpilejjsy, trephining, 504 Jacobson's n., 116 organ, 300 .Taw, lower, dislocation, 579 upper, excision, 579 Joints. J'ide Aiticulatious. Jugular ganglion, IK! vein, anterior, 2!!. 37, 30, 34, 35. 39. 50, 70, 117, 174, 177. 645 external. 32. 60. 30, 34, 35, 39, 50. 70, 174. 208, 645 jugulo - c e ]) h a 1 i c liranch. 23 line. 23, 32, 27,623 pnlsiition, 32 termination, 18 internal, 61, 62, 73, 35, 39, 41, 50, 70, 78 129, 164, 174. 645 jMisition. Is relations. 73 posterior. 30, 50, 70, 208, 645 extiTual, :!7 Jngnlo-cephalic branch of exter- nal jugular v., 23 Keratitis, intei-stitial, 362, 363 Keratosis senilis, 593 Key, foramen, 441, 544 L. Labial a,, inferior. 643. 608.613. 640. 682 anastomosis, 643 branch of nifra-orbital n., 675, 697, 620, 695 Labial glands, 210 vein, inferior, 117 Labyrinth, :!99. 131. ('/(/( In- ternal Ear, bony, 431 external view. 427 internal view, 430 mendiranous, l!!l, 432 diagram, 439 vestibule, l:!l Lacrymal api)arijtus, liol, 350, 355 dissection, l'>51 artery, 323, 336, 334 branches, 33(5 bone, frac^tiu'e, 586 canal, 3,52 canal iculi, 351, 648, 355, 653 canaliculus. 350 caruncle, 649 duet, 352 ducts, orilice of, 355, 653 f(>S!-a, 316 gland, 323, 328, 326, 330, 334. 339. 355. 653 infeiior, 32-< .superior, 328 sus))en,sory ligament, 328 groove, iil7 nerve, :!23, 327, 675, 326, 339, 343 ptmctum, 649 Siic, 352, ,591, 321, 350, 355, 653 abscess. ()44 Lacrymo-nasal duct, 3,52, 350 Lacuna' lateralis, 719 Lacus lacrvnialis, 648 Lambda, .57:'., 588 Landxloid suture, .573, 588 Lamina cinerea, 459, 516, 565 cribrosii, 3(il, 362 fusca, ,362 of orbital fascia, 323 qnatlrigeniina, 537, 513 spiralis, 432, 430, 434, 436 siii)rachoroidca, 362. 374, 369 vitrea, 374 Lamina' of cerebellum, .558 Lamin.ated tubercle of cerebel- lum, 562 Lancisi n.'s, 517 Landmarks, cranio-cerebral, 499 of .luricle, 601 of cerebrum, 46S of cranium, 587, 589 of ear, 701 of eye, 593 of face, .592 of frontal lobe. 508 of limbic lobe, 499 of ne<'k, 17 of ncei|)ital lobe, 509 of ])ariet.al lolie. .509 of pinna. 701 of tem]X)ral lobe, 569 of temi)oro-siihenoid lobe, .509 Laryngeal a., inferior, 145. 265, 263 superior, 91,26,5, 50,70. 78. 123, 251, 263 r52 INDEX. Laryngeal asthma, 262 "braiK-h of inferior thyroid a., 145 nerve. 123 external, 2G2, 51, 71, 78, 79, 177 inferior, W inteinal. 262. 51, 71, 78, 79, 177, 251, 263 recurrent, 82. 127, 262, 71, 78, 263 superior, 62, 81, 262 irritation, 82 ]iaralysis, 82 pouch, 269 sac, 269 Laryngismus stridulus, 262 Laryngo-pharynx, 227, 212, 296 Laryngoscopic exiiiiii nation, 276 Laryngotoniy. 2-54, 552, 556 ventricU\ 51H, 497, 516, 523 body, 51X, 519, 528, 569 ol, l!l.'> of subclavian a., V.Vi collateral circula- tion, !:!.'>, 133 first portion, 115."), 1()(> second ])ortii)n, lli.'i, \m third portion, 16(>, l(i9 collateral circu- lation, 170 of temporal superficial a., 1!).-) of tlivroid a., inferior, 145, 179, 177 superior, l'<7,177 of vertebral a., 1415, 175 Limbic lobe, landmarks. 499 Line for bracbial n. plexus, 20, 67 for carotid a. , common, 20, 27, 67 external, f«>. 20. 67 internal, 20. 67 for dental n., inferior. 20,67 for facial a., 20. 27, 67 nerve, 20. 27. 67 for fissure of Kolanilo, 507, 506 of Sylvius, 507. 506 tor frontal fissure, inferior, 50.S, 506 superior, 5tH, 506 for innominate a., 20, 67 for iutra-parietal fissure, 509 for jugular v., external, 23, 3->, 27 for lingual a., 20. 67 for longitudinal fi.ssure, 507, 506 for occipital fissure, posterior, 506 for parieto-occipital lissure, 50.y for precentral fissure, 508 for spinal acces.sorv n., 20. 67 for .Steuson's duet, 27 for snliclavian a., 20. 67 for temporo-spbiMiokl lissure. middle, 510, 506 superior, 510, 506 for thyroid a., inferior, 20,67 superior, 20. 67 for transverse fissure, 507 Keid's ba.se, 507, 506, 589 Lines for carotid a., lonnnon, 623 for connnon carotid a., 623 for external jugnlar v.. 623 for facial a., 623 vein, 623 for li.ssures of brain, 506 for jugular v., external. 623 for lateral sinus. I'i'i. 721 Lines for longitudinal sinus, supe- rior, 7I!I for sigmoid sinus, 7'.!:>, 721 for Stenson's duct, 623 of cerebral fissures, 689 Lingual a., 91, 114, 50. 70, 78, 79, 105, 133, 177 anast<)mosis, 1 1 1 irregularities, 190 ligation, (54, LSI, 177 line for, 20, 67 operation to expose, 183 relations, 9"i branch of glosso-pliarvngeal n., 119 convolution, 495, 488, 494, 497 lymphatic glands, 7015 lierve, 11-3, (i^M, 78, 202, 678. 686, 695 branches, (iss irritation, '^'XA o])eratioii to expose, 202 relations, Wi resection, 205 tonsil, 319 triangle, 04 dissection, 64 vein, 9-.', IIJ. 35. 50, 51, 70, 177. 645 relations, 11 2 Lingualis m., 220 inferior, 220, 221 superior, 220, 221 Lingula, 513 of cerebellum, 561 Lip, lymphatics, 210 Lips, 210 lymphatic vessels, 223 Lobe of cerebellum, biveutral, 560 central, ,561 digastric, 562 posterior inferior, 562, 560 superior, 561, 560 quadrate, .5(!1, 560 slender, 560 of cerebrum, central, 470 frontal, 475, 4.-'l, 471 inner surface, 485 landmarks, 508 orbital surface, 482 lind)ic, landmarks, 499 occipital, 176, 490, 458 i n f e r i o r surface, 494 landmarks, 509 parietal, 476, 485 landmarks, 509 quadrate, 516 temporal, 4^1, 491, 471 inferior surface, 494 latid marks, 509 teniporo-sphenoid, 456. 4^1. 491, 458, 565. Vide Robe of Brain, Tem- poral, landmarks, ,509 Lobes of brain, frontal, 4,'>() temporal, I5(). ]'i(lr Lobe, Temporo-.^ijlie- noid. of cerebellum, .5,")8, 561, 562 of cerebrum, 469 of i)arotid gland, 656 optic, 5;i-< Lobule of cerehellum, erescenlic, anterior, 560 l)osterior, 560 of cerebrum. ]"nli ('^ Longitudinal lissure. 459, 480 line, 507, 506 of brain, 467 median sulcus, 542 sinus, inferior, 724, 714 superior, 719, 709.714, 715 course, 592 line, 719 wounds, 719 LongTis colli m., 155, 39, 152 action, 156 in.sertion, 1.55 nerve stipply, 156 origin, 155 relations, 155 Ludwig's angina, 64 Lung, apex, 18 Lripus vtilgaris, 293 Luscbka, ]iharyngeal tonsil, 232 Lj'inpbatie duct, KiO gland, auricular, posterior, 157 glands, auricular, 702 buccal, 702 cervical, deep, 157 superlicial, 157 infra<-Ia\ic'ular, 157 lingual, 703 uiastoid, 702 maxillary, 703 occipital! 702, 157 of carotid sheath, 73 of head, 702 of neck, 159, 157 parotid, 6.57, 702, 157 posterior i)liaryngeal, 7015 submaxillary, 63, 702, 157 sulioceipital, 702 Lymphatics, auricular, jiostcrior, 615 frontal, 615 occipital, 612 of brain, 445 of external aialitory meatus, 407 of eyeball, 392 of eyelids, 6.55 of face, 703 of internal ear, 438 of larviix, 265 54 INDEX. Lymphatics of lip, 210, 223 of inieklle ear, 425 of mouth, 223 of nasal foss;e. 307 of neck, 157 of nose, 2^t() of orbit, 351 of jiharynx, 238 of pinna, 403, 665 of ptervgo-niaxillary region, 6«7 ' of scalp, 613, 703 of tongue, 223 of tonsils, 225 posterior auricular, 615 temporal, 615 Lymph passage of eve, anterior, 392 posterior, 392 spaces, intervaginal, 385 of cornea, 392 of iris, 392 perichoroid. 393 supra- \aginal, 324, 395 Lyre, 522, 533 M. MacEven, supra-meatal triangle, 415 Macroglossia, 223 Macula lutea, 380, 381 Magendie, foramen, 441, 544 Malar branch of fncial n., 609, 613, 620 of lacrvnial a.. 336 of orldtal n., 351, 694 of tcniporo-facial n., (ifi9 of teniporo-iualar n., 676 Malleolus, ligament, suspensory, 422 Malleus, 423, 405, 409, 413 caries, 424 handle. 418, 422 head, 422 ligament, anterior, 424 external, 424, 409 internal, 424 superior, 423, 434 suspensory, 434, 409, 413 manubrium, 423 processus brevis, 433 gracilis, 423 short process, 418 Mammary a., inti-rnal, 146, 78, 79, 129, 133 gland, carcinoma, pain, 45 Manubrium of malleus, 423 jMargiual convolutions, 485, 488, 497, 516 Masseter m., 6.50. 621, 627 action, (iiio blood supply, 660 insertion, (i59 nerve suj)ply, 660 origin, 650 relations, (i.59 Masseteric a., (H4, 620, 678, 682 nerve, 687, 621. 678 portion of Stcnson's duct, 659 Mastoid abscess, 420 antrum, 412, 413 trephining, 415 artery, 95, 96 branch of auricularis maguus nerve, 38 of small occipital nerve, 51 cells, 412, 416, 413 disease, pus, 423 lymphatic glands, 702 nerve, 30. 34 process, 5;il operations, 723 vein, 37 Maxilla, inferior condyle, exci- sion. .584 excision, 583 fracture, 586, 581 superior, excision, 579 line of incision, 572 fracture, 586 Maxillary a., internal. 679, 680, 133. 620, 621, 678, 682, 686. 695 branches, 683. 682 divisions, 683 division of internal maxillarv a., 683 lymphatic glands, internal, ■ 703 nerve, inferior. 687. 730, 326, 339, 686, 695, 715 branches, 687 neurectomy of in- tracranial, 730 structures in- \olved, 730 resection, 199 superior, 693, 698, 7:;0, 326, 339, 678, 686, 715 brandies, 694 course, 693 infra iirl)ital branch, 609 neurectomy of, in- tracranial, 730 structures in- volved, 730 resection, 199 sinus, 313. Mile Antrum of Highmoie. vein, anterior, 6'^7, 35. 645 internal, 6«7, 35, 50, 70, 645 Measurements of orbit, 317 Meatus, auditorv, external, 403, 405, 409 blood suiiply, 404 lymphatics. 407 nerve sujiply, 407 occlusion, 404 relations, 404 sinus, 403 M'ins, 107 inferior, 212 of no.se, 296 Meatus of nose, fourth, 299 inferior, 299, 296, 298. 350 middle, 399, 212, 296, 298, 350 atrium, 299 superior, 299, 212,296, 298 Meckel's ganglion, 097, 303, 686, 690 branches, 697 removal, 699 structures involved, 699 space, 730 Media, refracting, of eye, 361 Median fissure, longitudinal, 544 posterior, 542 nerve, 149 sulcus, longitudinal, 542 Medulla oblongata. 461, 553, 516, 539, 552 fissure, antero- lateral, 554 anterior median, 55.3, 552 posterior median, 553 function, 558 funiculus dentatus, 536 gracilis, 536 position, 456 pyramid, anterior, 458 P3'ramids, 554 decussation, 553, ,554. 552 tract, lateral, .554, 536, 552, 556 pyramidal, 552 Medullary velum, posterior, 562 superior, 543, 516, 536, 542, 560. Vide Valve of Vieussens. Meibomian glands. 593, 6,52, 346, 355, 632, 653 ducts, 648. 353 orifice, 653 Melanotic s;n'e(ima of choroid, 379 Membrana basilaris, 432 flaccida, 419. 409 nictitans, 321 rudimentarj', 651 tensa, 419 tympani, 416, 405, 409, 413 artilicial, 420 blood supply, 420 external view, 418 folds. 419 inner vail. 420 internal view, 422 mucous membrane, 430 nerve sup])ly, 420 paracentesis, 419 perforation, 419 promontory, 430 jivraniid, 420 rupture, 4I!I .seciuidaria, 420, 4,32 Membrane, crico tinroid, 24, 255, 123, 251. 254 hyaloid, 385 b'vpo-glossal, 216, 230, 270 IX HEX. 755 Membrane, intci'sutiiial, (!17 mucmis, of larynx. 'Jdli of iiieniliiana tviiipani. of llloutll, "Jl.'i of iiasiil fo>s:v, :il)0 of luise, iieive supply, :!()-J of pharynx, 232 of liownian. 303 of luain. 704 of Deseeniet. 363 of Reissner, i'.K pituitary, 300 nerve supply, 303 pupillary, 3(i7 Sehneideriaii, 300 nerve supply. 30'> Sluapnell's, 41!)", 418 synovial, of teiuporo-nuixil- larv articulatiiiM, ."i74 thvro-livoi,!. ■,>,-..-,, 123, 212, 251. 254. 263 Meniluanes of brain, 43>^ Menihranoiis cuclili'a. 437 labyrinth. 431. 432 ' diaKrani, 439 semieireular canals, 437 M^'ni^re's disease, 437 Meningeal a., anterior, 734 middle. .^i92. (i-^:!. 733. 303. 682. 688, 690, 695, 709, 714. 715 brauehes, 733, 734 wounds, 734 posterior, 95, 449, 735, 444 small. fi'<3. 735, 682. 686. 695 branch of anterior ethmoid artery, 337 of a.sceuding pharyngeal artery, 97 of gl osso-p h a r y n g e a 1 nerve, llfi of pueuuiogastric nerve, 81 vein, 735 Meningitis, 423 Meningocele. 591 sincipital. 28() Mental a.. (17 nerve, (i7(i, 609. 620. 686 Mever, .spheno-ethnioid recess of, 299 Middle ear, 399. 407 blood supi)ly, 425 disease. 420 l(i Modiolus, 432. 434. 436 Molar glands. 213 Moll, sweat glan. foramen, ."ils, 537, 516, 519. 528. 529 Monticnlis ccrebelli, ,501 clivus, .'>()1 cnlmen, 501 Morgagni, sinus of, 2:!1. 229 Motor areas of brain, 1 19, 501 centers of brain, ."lOO oculi n., 341, 539. 715 Mouth, 209, 213, 591 angles, 210 anterior view, 239 diaphragm of, 107 dissection, 209 lymphatics, 223 mucous niemliranc, 215 muscles. 031 section, 212 vestibule. 210. 212 Movements of larynx, 24, 281 JIucocele of antrum of High- more, 312 Mucous gland of Kustachian tube, 411 of laryn.N, 209 of nose, 302 membrane of larynx, 209 of mend>rana tympani, 420 of mouth, 215 of nasd fo.ssic, 300 of nose, nerve supi)ly, 302 of pharynx, 232 of urethra, 637 Miiller, paljiebral muscle, supe- rior, 353 ring niuscli' uf, 373 Multiliilus spin;e m.. 39 Muscie volitantes, 385 Muscle, anterior dilator narium, 627 antitragicus, 005. 401, 663 arvteno - ejiiglotlidens, 261, 258. 259. 263 arvtenoideus, 256. 258, 259, '263 attolens aurem, OO.'i, 627 attrahens aurem. OO.'i. 627 azvgos uvuhc, 240. 242. 243 bu'ecinator. 037. 229, 242, 621. 627, 678. 686 bnlbo-cavLM'nosus. Oo 1 ciliary. 30-^, 360, 365. 369, " 376. 394 of orbicularis palpebra- rum, 0:!3 complexns. 39. 50. 71, 78 compre,s.sbr narium. 627 minor, 627 nasi, 629 constrictor, of pliarvnx, in- ferior. 22-*. 71. 79. 123. 177, 229. 236. 251 middii'. ■:■}■'. 50. 71.79, 105, 229 supt-rior. 22"^. 71, 79. 229 corrugator snpercilii, 634, 346. 632 Muscle, crico-arytenoideus later- alis, 201. 259 posticus, 2.">0, 258. 259 cricothyroid. 2.'i.'>. 123, 251 jiosteridr. 263 dcpre.s.sor al;e nasi. 030 angnli oris. 627 labii infrrioris. 030. 627 digastric. 9s. 71. 78, 79. 105, 117 anterior billy. 50 posterior lielly. 50 dilator naris, 029 narium. antirioi, 627 jioslerior. 627 external jiterygdid. (I"9, 678 genio-livo-gldssns, 111. 220, 78, 79, 105, 109. 212, 296 ginio-hvoid. 107, 78. 79, 105. 109, 212. 296 helicis major, 0(i."). 401. 663 minor. 005, 401, 663 Horner's, (i33. Vide Tensor Tarsi Muscle. hvo-glossns. 10-J. 220. 71,78, 79, 105, 109, 177 inferior obIi(|nr. 347, 320, 339. 632 reclns. 632 internal jili rv^Luid. Il-O. 303, 678. 686. 690 la.xator tymjiani. 424 levator angnli oris. 0,30, 627 scapnhe. 39. 50, 71, 152 glandiihe ilivroidea;, 122, 124, 251 labii inl'crioris, 030 snpeiioris, 035, 627 aUcque nasi, 029, 627 menti, 627 palati, 245. 242, 243 palpcbric sniii-iinris. 320, 32^. 0.'.."). 326. 330, 334, 353. 355. 653 paliiebial. 339 lingual is. 220 inferior, 220. 221 superior. 220. 221 longus colli. l.")5. 39. 152 niasseter. 0.")9. 621, 627 multilidus s]>iiue, 39 mvlo-hvoid, 107. 50, 71, 78. 79. 107. 109. 177, 296 oblique, infnior. :117. 326, 330. 334, 339 346. 632 superior. 331. 326.330. 334 jiulley, 331. 334 obliquus anris, 6()5, 401, 663 capitis inferioris. 152 superioris. 152 occipitalis, 015. 79. Vide Oecipi to-frontal is Muscle. oceii)ito-fron talis. 015 omohyoid, 119. 71. 117 anterior belly. 119. 50 posterior belly, 120. 50 756 INDEX. Muscle, orbicularis oris, 634, 627 palpi'l)raruMi, (i30, 321, 353, 627 palatn-gl.issus, :.':J0, 240, 105, 109, 242, 243 palatd-pharvugc'us, 245, 242, 243 palpebral, superi(.)r, of Mul- ler, 353 platvsma nivoidt-s, 31, 30, 177, 621, 627 posterior dilatornarium, 627 pterygoid, external, 679, 678 ■internal, OSO, 303, 678, 686, 690 P3-r.aniidalis nasi, 626, 627 quadratus nienti. \'i(h De- pressor Labii Inferioris Muscle, rectus capitis anticus major, 156, 78, 79, 152 minor, 156, 152 lateralis, 156, 152 external, 342, 321, 326, 330, 334, 339 inferior, 347, 339, 346, 496 internal, 342, 326, 330, 334, 339 superior, 331, 320, 326, 330, 334, 339, 346, 632 retrahens aurem, 605, 627 ring, of Miiller, 373 risorius, 31, 634, 627 salpingo - pharyngeus, 245, 243 Sautorini's. Vide Risorius Muscle, scalenus antieus, 1.^3. 39, 71, 78, 79, 129. 152 medius, 154,39, 50,71, 129, 152 posticus, 154, 39, 129, 152 semispinalis colli, 39 serratus magnus, 50, 71 sphincter oculi. IVrfe Or- bicularis Palpebrarum Muscle. oris. V'kJi' Orl>icularis Oris Muscle, splenius, 39, 78, 79 capitis, 50, 71, 152 stapedius, 425, 422 sterno-cleido-mastoid, 17, 48. Vitle Muscle, Steruo-Mas- stoid. stenio-livoid, 120, 39, 50, 71, 78, 117 sterno-niasldiil, 17, 4^^ 39, 41, 50, 71, 78, 117, 177 stenio-tlivroid, 121, 39, 50, 71, 78, 117 stvlo-glo.^sus, 111, 220, 79, 105. 109 stvlo-livoid, '.)■<. 50, 51, 71, 105, 177 stvlii-|il],'ii vngcus, 115, 79, 105, 229 siipcrlicial crrvical, 31 superior rectus, 632 Muscle, temporal, 625, 321, 621, 678, 686 tensor palati. 245, 303, 690 tarsi, 63:!, 321, 346, 355, 632, 653 tympani, 425, 405, 422 thyro-arytenoidi'us, 2(il, 259 ihyro-epiglottideus, 261 thyro-hyoid, 121, 50, 71, 87 trachelo-niastoid. 152 tragicus, 66.5, 401, 663 transversalis colli, 39 trausversus auris, 665, 401, 663 deep, 613 trapezius, 39, 41, 50, 71, 78, 79 zygomaticus major, 636, 627 minor, 637, 627 Muscles, constrictor, of pharj'ux, 228, 231, 229 intrinsic, of pinna, 400, 401, 663 of auricle, intrinsic, 400 of ear, 605, 665 of esophagus, 229 of eyebrows, 630 of eyelids, 630 of face, 626, 613, 627 of larynx, 258, 259 extrinsic, 262 intrinsic, 262 of mouth, 634 of neck, dissection, 48 of nose, 626 of orbit, 328, 326. 330 of palate, paralysis, 247 of pharynx, 227 paralysis, 247 of scalp, 613, 627 of soft palate, 242, 243 of tongue, 219 dissection, 108 extrinsic, 219, 109 intrinsic, 220 of tympanum, 425 prevertebrial, 1,55, 152 recti, common tendon, in- ferior, 347 superior, 347 Muscular branch of facial a., 643 of ophthalmic artery, 337 sense, area (jf, 500 Musculo-cutaneous n., 149 Musculo-spiral n., 149 Mylo-hvoiil a., 104, 0.83, 678, 682, 686, 695 muscle, 107, 50, 71, 78, 79, 107, 109, 117, 177, 296 action, 107 blood supjily, 107 insertion, 107 nerve supply, 107 origin, 107 relations, 107 nerve, 101, 6i>l. 51, 678, 686. 695 branches. 695 incisive branch, 691 mental branch, 691 Myopia, 363, 396 Myopic eye, 389 Myxedema, 126 N. Nares, anterior, 284, 594 posterior, 232, 236 Nasal a., 337 anastomosis, 337 lateral, 613, 682, 695 bones, 28G fracture, 2^6, 586 braudi of anterior ethmoid a.. 337 of infra-orbital n., 675, 097, 620 of Meckel's ganglion, 698 catarrh, 301 cavities, 294 blood supply, 307 divisions. 300 \eins, 307 columna, 594 douche, 308 duct, 3.52, 594, 314 orifice, 299, 298 fossse, 294 anterior view, 306 divisions, 300 lymphatics, 307 mucous membrane, 300 olfactory portion, 300 posterior view, 309 respiratory portion, 300 nerve, 302. :i:;2. 075. 697, 303, 326. 339, 343, 609, 620, 690, 695 branches, 335 external branch, 676 inferior, 303 naso-lal)ial branch, 629 of Meckel's ganglion, 698 superior, 698. 303, 690 nerves, inferior, 690 polvpi, 301 septum, 294, 236, 291, 306, 714 deviation, 294 perforation, 294 Naso-labial branch of na.sal n., 629 Naso-iialatine a., 684, 690 branch of Meckel's ganglion, 698 nerve, 309, 303 Na.so-pharvnx, 227, 212, 296 Nates, 538", 542, 556. 560 brachia. 543 Near-sightedness, 363 Nebula, 364 Neck, ab-scess of, 31, 47 arteries, ligation, 160 articulations, ,573, 579 back of, surface anatomy, 24 bursa\ 156 carbuncle. 26 develo]iment. 25 dissection. 17. 26 fascia, deep, 34 su))erlicial, 26 incision for dissection, 623 injuries, 31 length, 17 « i.\Di:.\'. 757 Neck, Ivmiiliiitic ulamls, \M), 157 vrssi'ls. 157 iiiiisfU's, (lissfftioii, 4S iieiv.s, 70, 71 operations iipun, I!h; skin, 17, 'Jli surface niai'klii;is. 21 transverse seetioii, 39 triangles, ,')-! anterior. H tlia^jrani, 55 dissection, 51 posterior, 18 veins, 35, 645 vessels, 70, 71 Necrosis of tnrliinated liones, :?00 Nerve, al)ilucent. Hi,'), 1:!^, 539. I7(/c Nerve, Si.xtli Cranial. ansii liypojilossi, 71 anterior auricnlar, IWS superior dental, (597, 695 temporal, 678, 686 Arnold's, 81 auditory, i:W, -K!."), 7il), 539. ['/(/(■ Nerve, Kiglith Cranial. aurieiUar, ><1 anterior, G*^*^ great, 30, 609 of auricularis magnus, 3S posterior, it7, 61'-J, iV<(i, 51, 70, 71, 78, 79, 203 auricularis uiagnus, 32, 38, 34, 51 branches, 3,-^ relation, 206 auriculo-teni]>oral, (il'i. (W8, 193, 303, 609, 613, 620, 678, 686, 690, 695 divisions, 688 operation to expose, 20.5, 193 buccal, ii(ilt, 609, 613, 620, 678, 695 long, IW-^, 686 cardi.ae, 78, 79 cervical, pneumogastric, 83 sympathetic, infe- rior, 85 superior, 84 middle. So carotid, of glossopharyngeal, 116 cervical, eighth, 149 anterior division, 79 fifth, 149 anterior division, 39, 71, 78 fourth, 149 anterior division, 71, 78 second, anterior division, 71, 78 seventh. 149 anterior division, 71, 78 sixth, 149 anterior divi.sion, 39, 71, 78 Nerve, cervical, snperlirial, I,"), 34, 51 relations, o{k; third, anterior division, 71, 78 eervieo-t'aeial. (ili!) hrariehes. (111!) chorda tvnipani, 126, 691, 422, 678, 686, 695 in otitis media, 426 ciliary, 376 long, 33,j, 376 posterior, 326, 377 sliort, 339, 376 posterior, 377 circnnille.x, 149 cochlear, 138, .Kji; commnniiuintes liypoglossi, (i6, 71 noni, 6(i cranial, 715,^0/ eighth. l(ir>, 458, 542, 556 origin, 552 eleventh, ,')7. 16(i. 458, 542, 556 origin. 552 fifth, 4li,'., 326, 339, 458, 542, 556 ophtlialiniedix ision, 326 origin, 552 fourth, :!.'7. -U\-2. 326, 339 343, 458, 542. 556, 560. V i d e Pat hetic Nerve, origin. 552 recurrent branch, 326 ninth, 466. 458, 542, 556 origin, 552 second, 462. (VrfeNerve, Optic, seventh, 465 origin. 552 sixth. 341. 46.">, 326, 339. 458 tc-nth. 7li. 166, 458, 542, 556 origin, 552 third, 3n, 462, 326, 458. 17* Nerve, Ocnlo-motor. origin. 552 twelftli, 104. 467, 458 origin, 552 cutaneou.s, internal, 149 lesser internal, 149 deej) temporal, 687 dental, anterior superior, 697, 695 inferior, 691, 678, 686, 695 line, 20, 67 operation to exjjose, 182 resection, 200 middle superior, 694, 695 iwsterior superior, (i94, 695, 678, 686 Nerve, desci'ndens hvpoglossi, 73, 41, 51, 71, 78 noni, 73 digastric, 669 eighth cervical, 149 anieriordivisioo, 79 cranial, K;,".. 729, 458, 542, 715 eleventlicrani.-il, 07, 466, 729, 458. 542 715 cMernal palatine, 611(1 resi)iiatory, of Hell, 153 SU|ierticial lietro,sal, 7,'!3 facial, 46,">, 666, 728, 51, 71, 78, 79, 203, 539, 620,621. („/, Nerve, J^eventh Cranial. briinches. 666 buccal l.iancli, 669,609, 613, 620 course, 66() digastric branch, 669 division of, facial, 666 intra-cranial. 666 temporal. 66(! infra-ma.\illarv Ijranch, 670. 34, 620 infia (irbilal )iiaiH4i, 669, 609, 613, 620 line, 20, 27. 67 malar branch, 669, 609, 613, 620 of auriculaiis magnus, 38 oiieration to expose, 675, 203 paralysis, (i70 stretching, 205 stylo-hyoid Ijranch, 669 supi'a-maxiniu'\' br.-tnch, 6-;0, 609, 613, 620 temiionil luanch, 612, 609, 613, 620 fifth cervical, 149 anterior division, 78 cranial, 465, 675, 728, 326, 339, 458, 542, 695, 715 branches, 67.5 ophtlialmie d i v i - sion, 326 first cervical, 539 cranial, 461, 727. Vide Nerve, Olfactory, thoracic, anterior divi- sion, 79 fourth cervical, 149 anterior d i v i- sion. 78 cranial, 327, 462. 7-J,'', 326. 339. 343, 458, 542, 715, l'i(/r Nei'\e, Pa- thetic, recmrent bra n e h, 326 frontal, 327. 326, 339, 343 glo.s.so-pharvngcal. 115. MM, 729.' 79. 539. (7ranclies, 687 neurectomy, intra- cranial, 730 structures in- volved, 730 resection, 199 superior, 693, 698, 730, 326, 339, 678, 636, 715 branches, 694 course, 693 infra-orliital branch, 609 neurectomy, intra- cranial, 730 structures in- volved, 730 resection, 199 median, 149 meningeal, of glosso-i)haryn- geal, 11 1; of pneiimogastric. si mental, 676, 609. 620, 686 middle superior dental, 694, 695 motor oculi, 341. 539, 715 musculo-cutaneous, 149 musculo-spiral, 149 mylo-hvoid, 101, 691, 51, 71, 117, 678. 686, 695 branches, 691, 695 incisive branch, 691 mental branch, 691 nasal, 302. 332, 675. 697, 303, 326, 339, 343. 609, 620, 690, 695 liranches, 33.> external liranch. 676 inferior, 303, 690 nasolal)ial liraneli, 629 of Meckel'sganglion. 698 superior, (;9s, 303, 690 na.so-labial branch of nasal, 629 nasopalatine, 302, 698, 303, 690 nintii cranial, 466, 729, 458, 542, 715 occipital, great, 609. 613 small, 612, 609. 613 occipitalis major, 61'J, 79 minor. 38, 612. 30,34.15 mastoid braneh. 34 relations, 206 oculo-motor, 3)4 1, 462, 727. l7(/c Nerve, Third Cranial, olfactory, 302, 461, 727, 303, 690,' Viilf Nerve, Finst Cranial, ophthalmic, 326, 339. 343, 695. 715 optic. 3 12. 162. 727. 320, 326. 330. 334. 360, 369 458, 516. 5r2, 565,715. \i^. 303. 690 palpebral, 675, (197, 620, 695 par.s intermedia of Wrisbera, 539 pathetic, 327, 462, 728, 539, Vide Nerve, Fourth Cra- nial, petrosal, external superficial, 84 small, 426 superficial external, 733 large, 732 small, 7:!2 pharyngeal, 698, 303, 690 of glossoiiharyngeal, 116 ofpneumogastric, 81 phrenic, 60, 65, 71, 78, 79, 149 plexus, axillary, 148. T'irfe Nerve Plexus, Bra- chial, brachial, 60, 14H, 51, 71, 149, 208 branches, 148 formation, 148 line, 20 operation to expose, 208 stretching, 209 cervical, 4S, ()5, 44 branches, 48 descend i ngbrauches, 51, 208 superficial branches, 38 pharyngeal, 8], 116, 231 subtrapezial, 66 tympanic, 426 vertebial, 85 pneumogastric, 76, 466, 729, 39, 41, 78, 79, 164, 539. Vide Nerve, Tenth Cranial. liranches, 81 cardiac branches, cer- vical, 83 ganglia, 76 relations, 76 posterior auricular, 612, 666 sujierior ileiital, 694, 678, 686, 695 temiioral. 678, 686 pterygo-]ialatine. ()98 ramus subcutaneus mala;, 694 recxirrent Inanch of fourth cranial, 326 larvngcal, 82, 127, 78, 79 rhomboid, 149 INDEX. 759 Nervi", sccoiiil ciMvical. anterior tlivision, 78 cranial, l(i.">, 7'J7. I'/i/i NiMVf, Optir. seiisoiv, of |>anitiil f;laiul, (i,">7 ■ septal, of Meckel's ;;anf;li«>ii, (i!)s seventh cervical. 149 anterior division, 78 cranial. IH'i si.Mli cervical. 149 anterior division, 78 cranial. :!n. Id.'), 326, 339 343. 458 splieno-palaliiie. 303 spinal accessory. .")T, liH!, 39. 51, 71, 78, 79, 539. IV«/< Nerve, I'.lexenth Cranial, line. 20, 67 operation to expose, 182 resi-ction. .58, 205 sterno-uiastoid, 71 subscapular, lower, 149 niiadle, 149 upjier, 149 superlieial cervical. 34 siiperlicialis colli. 4,") supraacroiiiial, 4,'i. 34 snpra-clavieular. \h, 34 supra maxillary branch of facial, 1)71). 620 supra-orbital. :!-.'7, fill, 197, 326, 339, 609, 613, 620 neurecloniv, Gil operation to expose, 196, 197 supra scapular, 1,53, 51, 71, 149 supra-sternal, 4."), 34 supra-trix'hiear, l!','7, 611, 326, 339. 609, 613 neurectomy. Sll sympathetic. 78. 79 cervical portion. 83 temporal, anterior, (il'.?, 686 branch of facial, ()12, ()(>:i. 609, 613, 620 of orbital, l!.')!, <)12, 694, 609, 613 posterior, 613. 678 superficial, 6xH temjjoro facial, 669 branches. 669 ti-ni]ic)ro-malar. 351. 694 tenth. 7-J9. 715 cranial. 466, 458, 542 third, 727 cervical, anterior divi- sion, 78 cranial. 341. 462. 458. 326. Vide Oculo- motor Nerve, thoracic, external anterior. 149 fii-st. 149 anterior division , 7 9 Xerve, thoracic, internal anterior, 149 ]iosirrior, or Ion;;. 1.53, 51, 71, 149 to levator angnli scapulae muscle, 149 to lon;;us colli muscle, 149 to rhomboidei ninsele, 148 to .scaleni nuiscle, 149 to stylo hyoid muscle, 51 to snhclavius mu.scle, 148, 149 tonsillar, of glosso-pharvn- fical, 119 trifacial, 465, 675, 728, 339, 539. Vide Nerve, Fiflli Cranial, branches. 675 trifieminiis, 465. Vide Nerve, Fifth Cranial. trcKddear. 327. 462, 543. Vide Nerve, Fourth Cranial, twelfth, 729. 715 cranial, 467. 458 tympanic, of ^losso pharvu- ' «eal. 116, 426 ulnar. 149 vafius. 71). 729. I7(/c Nerve, Pnenmofaistric. vestibular, 438, 466 Vidian, 302, 698, 303, 690, 695 Nerves, ciliary, 379 cranial, oriijins, 552 superficial, origin, 458 deep temporal. 6^7 of face, 666, 609, 613, 620 of head, oi)er/itions, 196 of Lancisi, 517 of larynx, 2(i2. 263 of neek, 70, 71 operations. 196 of orbit. 327, 326, 339 arranf;enieiit, 342 of pteryKo-maxilUiry region, 687 of scalp, 611. 609, 613 of thyroid >;land, 126 plexus of. basilar, 715 infra-orbital, 669, 675 Nervi molles, 84. 644 Nervus vagus. 466 Neuralgia, trifacial. 698, 700 Neurectomy, intra-cranial, of in- ferior maxillary n., 730 of sui)erior maxillary n., 730 of supra-orbital n.. 611 of sn])ra trochlear n.. 611 Xidus hirnndinis. 562 .Ninth n.. 729. 715 oi-anial n.. 166, 458, 542, 556 origin. 552 Nodule of cerebellum, 562, 560 Nose, 2^<4, 594 air-chambei-s, accessory, 314 orifices, 298 ala;, 2'<4 b.i.se. 2.-^ 1 bUediiig from. 301 blo(Ml su|)ply, 285 bridge, 284 298, 298 298 sup- Nose, cartilages, 2H6 accessory, 293 at ba.si-,"290 lateral, 287 inferior. 286 sesiimoid. 293 dis.section, 284 divisions, 284 epithelioma, 2>'5 hemorrh,if;e from, 301 lobule, 2^4 lymphatics, 2X6 nieirtns, 296 fourth. 299 inferior, 299, 296, 350 middli-, 2:19, 296, 350 atrium of. 299 su|)erior. 299. 296, mucous ghuwls. 302 membrane, nerve ply, 302 nerve su))ply, 285 rodent ulcer, 285 section, 212 skin, 285 veins, 2K5 vestibule, 285, 303 wings, 284 Nose-bleed, 643 Notch of Hivini, 416 preoccipital, 476 supra-orbital. 316 Nuclei of brain. 536 of jions Varolii, .5,50 of tegmentum of cms bri, 5,53 Nucleirs, caudate, 525, 517, 542, 546, 556, 569 head, 536, 564 cuneate, 557 Deiters', 465 gracile, 557 lenticular. ,525, 54-*, 564, 565, 569 of lens, 391 olivary, superior, 550 red. 553 tegmental. 553 Nuhu, gland, 219 Oblique m., inferior. 347 320. 326, 330, 334, 339, 346, 362 action, 317 / insertion, 347 / nerve sui)i)ly, 348 origin, 347 superior, 331.326,330, 334 action, 331 insertion, 331 nerve sup])ly, 331 origin, 331 pnllev, 331. 334, 632 Obliquus aurisni.. 665, 401, 636 capitis inferjoris ni., 152 superioris m., 152 529, 565, 546, 760 INDEX. Occipital a.. !i:!, 50, 70, 133, 603, 608, 613, 640 anastomosis, 606 brandies, 94 irregularities, 1 95 ligation, 94, 195 operation to expose, 183, 192 relations, 93 convohrtioii, inferior, 491, 474, 477, 480 middle, 491, 474, 477, 480 superior, 491, 474, 477. 480 diploic v., 707, 705 fissure, inferior, 49(1 middle, 490, 477, 480 posterior, line. 506 superior. 490. 477, 480 trausvcisp, 490. 477, 480, 572 foranien, superior, 718 lobe, 476, 490. 458 inferior surface, 494 landmarks. 5(t9 lymphatic gland, 157 glands,' 702 lymphatics. 612 nerve, great. 612, 79, 609, 613 small, 612. 30, 34, 51, 609 613 mastoitl branch, 34 protuberance, external, 25, ,"591 sinus, 724. 715 suture, traMs\erse, 573 triangle, 54, 55 abscess, 59 content.s. 57 dissection, 57 vein, 95, 35, 645 relations. 95 Occipitalis major n.. 612 minor u., :is, 612 rehitions, 206 muscle, 615. 79. Vide Occi- pito-fron talis Muscle. Oecipito-angular region, 503 Occipito - frontalis aponeurosis, 61.5, 599, 627 muscle. 615 action, 615 aponeurosis, 615, 599, 627 blood supjily, 615 insertion. i'A'y nerve supply, 615 origin, (il5 relations. f>15 Occipito • tem))oral convolution, external, 495 Occlusion of Eustachian tube, 411 of external auditory meatus, 404 OcHlo-motor n., 341, 462, 727. Mtlc TInrd ('raiiial Xcrve. Olfactory l)nlh, l,5(i. 458, 483 fissure. 1.56. 4S2, 488, 497 nerve. 302, 461, 727, 303. 690. Villi- First Cranial Nerve. Olfactory portion of nasal fossx, 300 sulcus, 456 tract, 4.56, 462, 303, 458, 539, 690 Olivary body, .554, 458, 539, 552 corpus dentatum, 554 peduncle, 554 nucleus, superior, 550 Omo-hyoid m., 119, 71, 117 action, 120 belly, anterior, 119, 50 insertion, 120 origin. 119 posterior, 120, 50 insertion. 120 origin. 120 nerve supply, 120 tendon, 39' Onyx, 364 Operation, enucleation of eyeball, 396 esopliagotoray, 226 evisceration of eyeball, 396 excision of condyle of inferior maxilla, .584 of eyeball, 396 of inferior maxilla, 583 of larynx, 281 of superior maxilla, 579 for abscess, cerebellar, 511 extradural, 511 temporo-sphenoid, 511 for cleft palate. 215 for harelip, 210, 213, 644 hemorrhage in, 644 for headache, 512 for removal of Ga.sserian ganglion, 731 structures in- volved, 731 of parotid gland, 658 for tongue-tie, 1 15, 215 for traumatic ejiilepsy, 512 for trifacial neuralgia. 699 laryngotomy, 281, 279 ligation of carotid artery, common, 179 internal, 195 of inferior thyroid ar- tery, 179 of innominate artery, 160. 165 of lingual artery, 64 of occipital artery, 195 of subclavian artery, 132 third portion,169 of temporal artery, su- perficial, 195 of verteliral artery, 143, 175 on mastoid process, 723 resection of dental nerve, in- ferior, 200 of Gasserian ganglion, 199 of infra-orbital nerve, 199 of lingual nerve, 205 of maxillary nerve, in- ferior, 199 superior, 199 of spinal accessory nerve, 58, 205 Operation, rhinoplasty, 285 Rouge's, 300 stretching brachial nerve plexus, 209 facial nerve, 205 thyroidectomy 126 to expose auriculo-temporal nerve. 205, 193 brachial nerve plexus, 208 carotid artery, common, 182 external, 183 internal, 183 facial artery. 182, 183 nerve. 203 inferior dental nerve, 182 innominate artery, 164 lateral sinus, 510 lingual artery. 183 nerve, 202 occijiital artery, 183, 192 spinal accessory nerve, 182 subclavian artery, third portion, 167 supra-orbital arte r y, 197 nerve, 196 temporal artery, 193 thyroid artery, inferior, 174 superior, 183 vertebral arteiy, 174 to tap lateral ventricles, 511 tracheotomy, 122, 282, 279 upon nerves of head, 196 of neck, 196 Operculum, 470, 471 Ophthalmia, purulent, 361 Ophthalmic a., 335, 229, 334, 444, 715 branches, 335 muscular branches, 337 division of fifth cranial nerve, 326. 339 ganglion, 338 nerve, 343, 695, 715 vein, 337, 343 common, 338, 334 inferior, 338, 334 phlebitis, 338 pulsation, 338 superior. 338. 334 Optic chia.sm, 459, 334 commissure, 459, 458, 483, 494, 516, 539, 565 disc, 380. 381 lobes, 538 nerve, 342, 462. 727. 320. 326, 330, 334, 360, 369, 458, 516, 552, 565, 715. Viilc Second Cranial Nerve, division, 316 entrance of, 362 thalamus. ,526, ,538. 488, 497, 519, 523, 536, 542, 546, 552, 556, 569 pulvinar, 539 INDEX. 761 Optic tlKihuiuis, tul)pivle, nnte- rior, :">:{--( |iiistcriiu'. 'ilN tract, lii-i, 458. 539, 552, 565. 569 (li:iL;iaMi. 463 Orii si'iraui, IWd Orl)ifularis liliaiis, :!7t oris in., (i:!l, 627 action, (i3."i nerve supply, (i35 ri'latidiis, (;:>.) palpel)raniin in.. (i:!ll, 321, 353. 627 actiDii, U:!.'! insertion, (>;!;{ nerve .supply, 633 orifjin, (i30 relations, (530 Orl)it, 3U! abscess, 3-23 apex, 31 li arteries, 334 l)a.se. 31(> dissection, 316 enipliysenia. 323 exenteration of contenta, 396 floor, 316 lymphatics. .3.51 measurements. 317 muscles, 32-<, 326. 330 nerves, 3-37, 326, 339 arraufiement, 34'J perio.steum, 318, 320 pulsjitiou, 338 roof, 316 veins, 334 Orbital a., 608, 613, 640, 682 branch of Meckel's ganglion, 697 of superior maxillary n., 694 convolution, anterior, 483. 488. 497 inferior. 483 internal, 4s,'). 488. posterior. 4>.'>, 488. 497 fascia, 3J3, 320. 321 lamina, ,323 fat, 323. 321, 326, 632 foreign hofly, 323 fis,sure, 4.56, 4*2. r/rfeTrira- (liate Fissure. nerve, 3.51. 339, 678, 686, 695 temporal branch, 612, 609, 613. 620 sulcus. 4.")6 vein, 35. 645 Orbito-tarsal ligament, 652, 320, 321 Organ of Corti, 437 of hearinir, 399 Orifice, buccal. 210 of antrum of Highmore. 298 of aqueply. 214 nerve .supi)lv, 215 soft, 23"<, 212,' 236, 239, 296 cleft, 246 muscles, 242. 243 Palatine aponeurosis. 2 Hi, 242 a.si^'udinn. 92 desi'ending, 30T, 105 artery, (is4, 682 branch of a.scendiug pharyn- geal artiMv. 97 nerve, anterior. IS Palpebral art»»ry, 682 inferior, 337 superior, 337 branch of infr.i-orliital n., 675, 697, 620. 695 of lacrymal artery, 336 of supraorbital artery, 336 commissures, 648 fa.scia, (!52 fis.sure, 593. 649 ligaments, 6,52 muscle of Jliiller, superior, 353 portion of conjunctiva, 651 Palsy, Bell's, 670 Pannus, 364 Papilhe. circuiinallatc, 219, 109, 218. 236. 250 conjunctival, 353 tilitorm, 219 foliata, 219 fungiform, 219, 218, 250 lachrymaliie, 648 Papillitis, 445 Panu'cntesis of meinbrana tym- pani, 419 Paracentral convolution, 489 488, 497, 516 fissure, |M!I, 488. 497. 516 Parallel fissure, 192, 477 Paralysis of facial n., (i7l» of bypo-glossal nerve, 101 of larvngeal nerve, sui)erior, 82 of larynx, 262 of muscles of i)Iiarynx, 247 of jialate, 247 of tongue, 220 varieties, .504 Parietal artery, ascending, 447 convolution, ascending, 486, 474. 477. 480. Vide Post -cent la 1 Con\'olu- tion. inferior, l-ili, 480 posterior, 474 superior. 1S6, 477, 480 eniinenee.s, 592 fissure, 573, 572 lobe, 476, 485 laiKlmarks, ,509 Parieto-occii)itid fissure, 475, 474, 477, 480. 488. 494, 497. 516 Parieto-teniporal a., 447 Parotid ab.scess, 657 incision, 6,58 branch of post-ainicular a., 96 fascia, 656 gland, 63. 6.56. 157, 608. 613. 627. 640 contents. (i57 lobe of, c;irotid, 656 glenoid, 656 pterygoid, 656 relations, 656 removal, 658 sensory nerve supply, 657 wounds, 6.58 lymphatic glands, 657, 702 Par vagum. 4(i(i Pars basilaris,' 4H2, ciliaris retina;, 380 intermedia of Wrisberg, 465, 539 iridiea retina;, 380 optical retiuic. .380 orbitalis, 4«2 triangularis, 482 Patellar fos.s,a, 385 Pathetic n., 327, 462, 728, 539. Vide Cranial Xerve. Pectinate ligament of iris, 364 Peduncle of cerebellum, inferior, 567, 539. 542 middle, 567, 539. 542, 552 762 INDEX. Peduncle of cerebellum, superior, 543, 567, 536, 539, 542 of olivary body, 554 of piueal body, 516, 529, 536, 542, 556 Peduncles of cerebellum, 562 of cerebrum, 460, 550. Vide Crura Cerebri, of corpus callosum, 517 Peduueular fillers of cerebrum, 548 Perforated space, anterior, 459, 458 posterior, 400, 458 Perforation of membrana tym- pani, 419 of na.sal septum, 294 Perichoroid lymph sjiace, 392 Pericrauium, 617, 599 Periglottis, 270 Perilymph, 431, 432 Periorbita, 318 Periosteal branch of supraorbital a., 336 Periosteum of orbit, 318, 320 Pes accessorius, 531 anserinus, 670 hippocampi, 531, 523, 529 Petit, caual, 386, 360 ^ Petrosal uerye, external super- ficial, 84 small, 426 superficial exterual, 733 large, 732 small, 732 sinus, inferior, 726, 714,715 superior, 726, 715 throiulwsis, 423 Petrous ganglion, 116 Pharyngeal apoueurosis, 231, 229. 243 artery, ascend iiin. 97, 105, 70, 78, 79, 229 relations, 97 branch of ascending pharj'U- geal a., 97 of glosso-pharyngeal n., 116 of pneumogastric n., 81 bursa, 232, 233 diverticulum, 26 nerve, 69S, 303, 690 plexus, 81, 116, 231 pouch, 2(> recess, 232, 233 tonsil, 232, 233 hypertrophy, 232 of I.uschka', 232 vein, descending, 97 Pharyngitis, 232 Pharyugo-e.sophageal junction, 227 Pharynx, 227, 242 lilood supply, 238 coats, 'J'J7 constrictor m. 's, 228, 229 inferior, 71 middle, 71 superior, 71 di.ssection, 227 divisions, 227 fiMcigu Inidies, 227 interior, 236 lympliatic-s, 238 Pharynx, mucous membrane, 232 muscles, 227 nerve supply, 238 openings, 232 relations, 237 section, 212 veins, 238 Phlebitis cf ophthalmic v., 338 Phlebotomy, 32 Phlegmonous erysipelas, 616 Phrenic n., 60, 71, 78, 79, 149 Pia mater, 454 in hippocampal fissure, 546 nerve supply, 455 Pillar of fauces, 224 anterior, 212. 218, 250 posterior, 212, 218, 236. 250 of fornix, anterior, 522. 516, 529. 533. 536. 542, 546, 556 po.sterior, 522, 523, 536, 546 Pineal body, 53^^, 516, 536. 539, '542, 556, 560 peduncle, 516, 529 536, 542, 556 gland, 538. Mde Pineal Body. Pingueculic, 652 Pinna, 399, 601, 660, 665, 398, 405, 661 action, 665 blood supply, 400, 665 cartilage, 665 dermoid cyst, 400 development, 400 frost-bite, 400 gangrene, 400 intrinsic muscles, 401, 663 ligaments, 400 lymphatics. 403, 665 nerve supply, 403, 665 sebaceous cyst, 400 skin, 660 Pituitary body, 459, 343, 458, 516, 539. 552, 565,715 fossa, diaphragm, 717 memljrane, 300 nerve .supply, 303 Platysma myoides m., 31, 30, 177, 621, 627 action, 31 blood supply, 31 insertion, 31 nerve supply, 31 origin, 31 Plexus, choroid. 454, .526, 544, 519.523, 533,536,546, 565, 569 of nerves, axillary, 148. Vide I' lex us of Nerves, Brachial, basilar, 715 brachial, 60, 148, 51, 71, 149, 208 line for, 67 operation to expose, 208 stretching, 209 oervical, 4H, 65, 44 branches, 48 Plexus of nerves, cervical, de- scending branch, 45, 51, 208 dissection, 38, 65 superficial branches, 38 s u p r a - a c r o m i a 1 branch, 34 s u p r a - c 1 a v i eular branch, 34 infra-orbital, 669, 675 pharyngeal, 81, 116, 231 subtrapezial, 66 tympanic, 426 vertebral, 85 of veins, pterygoid, 687 parotideus, 670 Plica semilunaris, 651, 649 Pneumogastric n., 7(>, 466, 729, 39, 41, 78, 79, 164, 539. r/(/f Tenth Cra- nial Nerve, branches, 81 cardiac branches, cer- vical, 83 ganglia, 76 relations, 76 Poisoning, lead, 214 Pole of eyeball, anterior, 357 posterior, 357 Politzer's method of inflating middle ear, 411 Polypi, nasal, 301 Polypus of frontal sinus, 311 Pomum Adami, 273 Pons tarini, 460 Varolii, 460, 549, 458, 516, 539, 552, 560, 565 dissection, 549 hemorrliage, 550 nuclei, 550 position, 455 relations, 549 Portio dura, 466 mollis. 466 Porus opticus. 362, 380 Post-central convolution, 486. Vide Parietal Convolution, Ascending, fissure, 4K5, 474 Postero-lateral fontanel, 584 Post-olivary fissure, 554 Post-parietal convolution, 489 Post-pharyngeal abscess, 232 Pouch, glosso epiglottidean, 216 laryngeal, 269 pharyngeal, 26 Precentral fissure, 481, 474, 477, 480 line. .508 Precuneus, 516 convolution, 489 Prefrontal region of brain, 499 Preoccipital notch, 476 Presbyopia, 391 Preservation of brain, 717 Pretracheal fa.seia, 47. 39, 41 Prevertebral liraneli of ascending pliaryui;i-al a., 97 fascia, 46, 39, 41 muscles, 155, 152 Princeps cervicisa., 95, 133, 137 anastomosis, 95 INDEX. 763 Process, ciliiirv, 374, 360, 365 mastoid, ."ii)l Dluratidii upon, T-HS of incus, 418 of niallius. 418 verniifonn, of ocivbelluni, oui, :m-> Processes of tluia inater of brain, 717, 714 Processus bievis, l-Jo, 409 caudatus, 4(K(. 401. 663 e cereliello ad testes, ■'i43. Vide I'edunele of Cerebel- lum, iSuperior. gracilis, 4-J:i, 409 Profunda cei'vicis a,., 147, 133, 137. Vide Cervical Artery, Deep. Proniontorv of nienibrana tym- pini, 4-J(l Protuberance, external occipital, 25, .ii)l Pnissak's chamber, 409 Pterion, .".-i-i, 506 Pterygoid a., iw:!. 678 external, (i-^ I, 682 internal, 6-(! muscle, external, (>7!t, 678 .action, (M) blood supply, 680 insertion, 679 nerve supply, 680 orifiin. (!7!) relations. (i-<0 internal, (i~(>, 303. 678, 686. 690 action, (iso blood supply, 680 insertion, 6.80 nerve supply, 680 origin, 680 relations. Cr^O plexus of veins. 6^7 Ptervgo-maxillarv ligament, 231, 637, 229 ' region, H7i>, 678 abscess, 692 contents, 679 dissection, 676 hemorrhage into, 692 lymiiliatics, 687 nerves. 687 veins. 687 Pterygo-palatine a., 684, 682 foramen, 693 nerve, 698 Pulley for superior oblique m., 33l". 334. 632 Pulsation in jugular vein, exter- nal, 32 of (luni mater of brain, 711 of innominate a., 18 of ophthalmic v., 338 of or) lit, 338 Pulvinar, .')3-<. 539 Puncta lacbrvmalia, 594, 648, 346. 632. 649 Pupil. 367. 369 .\rgyll Uobertson, 367 Pupillary membrane. 367 Purulent conjuctivitis, 361 Pus in mastoid disease, 423 Pus in otitis media, 423 Pyrauii() m., insertion, 156 m., nerve sup- ply. 156 m., origin, l."i6 lateralis m., 156, 152 action, 1,56 insertion, 156 nerve supply, 156 origin, 1.56 muscle, external. 342, 321, 326. 330, 334. 339 action. 342 Rectus capitis muscle, external, insertion, 342 nerve sujijily, 342 origin. 312 inferior, 316, 347, 339, 632 action, 347 insertion, 347 nerve supj)ly, 347 origin, 347 internal. :'. 12. 326, 330, 334, 339 action, 312 insertion, 312 nerve supply, 342 origin, 3 12 superior, 331. 320, 326, 330. 334, 339, 346, 632 action, 331 in,sertion, 331 nerve sujijily, 332 Recurrent branch of lacrvmal a., 336 laryngeal n., (<2, 127, 71, 78, 79 ner\e of fourth cranial, 326 Red nuelius. ,5,53 Rellected portion of conjunctiva, 651 Reflex iris, 368 Refracting media of eye, 361 Region of brain. Broca's, 503 occipito-angular, 203 liiefiontjil, 499 silent, 499 Reid's ba.se line, 507. 506. 589 Keil, island, 470, 4S1, 5-ls, 471, 483, 546, 565, 569 gyri oiierti, 471 Reissner, menibiane, 432 Removal of bi-ain, 712 of Gasseriaii ganglion, 731 structures involved, 731 Resection, Gasseiian ganglion, 199 of dental n.. inferior, 200 of infra-orbital n., 199 * of lingual n., 205 of nuixillary n., inferior, 199 superior, 199 of spinal accessory n., 58, 205 Respiratory jmrtion of nasid fossae, 300 nerve of Bell, external, 153 Iv'i'stifdiin body. 465, 554, 557, 536. 542, 556 Kctiua, 3S0. 360, 381 blind sjiot. li-d blood supph, :!-ll central a.. 3':;i;. 360, 384 vein. 360, 384 Retinal a., 381 veins, 3<.'>. 381 Retrahens aurem m., 60.5, 627 action, 605 inserti(ui. 605 nerve supply, 605 origin, 605 Ketzius, foramen, 441, 544 Kliinolitlis, 300 Rhinoplasty, 285 764 INDEX. Rliinoscopy, anterior, 307 posterior, 308 Khoiiiboiil u., 149 Ridges, superciliary, 588 temporal, 592 Rima glottidis, 248, 26fi, 267 Risorins m., 31, (534, 627 action, 634 insertion, (534 nerve supply, 634 origin, 634 Risus sardonicus, 634 Rivini, notoh, 416 Rcident ulcer of nose, 285 Rolando, Ussure, 475, 474, 477, 480, 516 line, 507, 506 funiculus, 554, 557 tubercle, 557 Rostrum of corpus callosum, 517, 488, 497, 546 Rotation of cornea, 348 Rouge's operation, 300 Rupture of membrana tympaui, 419 S. Sac, lacrvnial, 352, 594, 321, 350, 355, 653 abscess, 644 larj'ngeal, 269 Saccule, 431, 437, 439 Saccus endolympbaticus, 437 Sagittal section of brain, 567 of eyelid, 353 suture, 573, 588 Salivary duct, oljstruction, 114 fistula, 658 Salpingo-pharyngeusm., 245,243 Santorini, cirtilage of, 275 fissure, 666, 401, 663 muscle, 634. Vide Risorius Muscle. Sarcoma, melanotic, of choroid, 379 of dura mater of brain, 711 Scala media, 432, 437, 439 tympani, 432, 436 v'estibuli, 432, 436 Scalene ra., posterior, 39 tubercle, 154 Scalenus anticus m., 153, 39, 71, 78, 79,129,152 action, 154 insertion, 153 nerve snjiply, 154 origin, 1.5,3 relations, 1,53 medius m., 151, 39, 50, 71, 129, 152 action, 154 insertion, 154 nerve .supply, 154 origin, 154 relations, 154 posticus m., 154, 129, 152 action, 151 insiM'tion, 154 nerve supply, 154 origin, 154 Scalp, 587, 601 abscess, 617 Scalp, areolar tissue, 616 arteries, 588, 605, 608, 613, 640 congestion, 015 dis,section, 601 fascia, 602, 603 hematoma, 617 inflammation, 617 layers, 601, 599 lymphatics, 612, 703 mobility, 616 muscles, 613, 627 nerves, 611, 609, 613 skin, 602 tumors, 5>t7, 616 veins, ()(t6, 35, 645 wounds, 602, 616 Scalping, 616 Scaphoid fossa, 660 Scapular a., posterior, 59, 146, 70, 133 anastomosis, 146 vein, posterior, 70 Schlemm, canal of, 362, 360, 365. 384. 394 Schneiderian membrane, 300 nerve supjilv, 302 Sclera, 361, 360, 365,369, 376, 381, 394 Scleral sulcus, 362 Sclerotic coat, 361 portion of conjunctiva, 358, 651 Sebaceous cyst of pinna, 400 gland of cilium, 353 Second cervical n., anterior divi- sion, 71, 78 cranial n,, 402, 727, Vide Optic Nerve, sight, 396 Section of brain, coronal, 567 .sagittal, 567 of cerebrum, 546 ofciliarj- region of eyeball, 365 of eye, 360 of eyelid, 353 of tongue, 221 trans\'erse, of neck, 39 Sections of brain, 567 Semicircular canal, ampulla, 432 external, 430, 427, 430 posterior, 427, 430, 439 .superior, 427, 430, 439 canals, 431, 427 membranous, 437 Semispinalis colli m., 39 Sensori-motor area of brain, 500 Sensory areas of brain, 499, 501 nerves of parotid gland, 657 root of lenticular ganglion, 335 Septa orbitale, 653 Septal branch of nasal n., 335 of .Meckel'sganglion, 698 cartil.-ige of nose, 293, 291 Septum, artery of, 307 linguic. 111, 220 lucidum, 522, 516, 523, 536, 542, 546, 556, 565 Septum, nasal, 294, 236, 291, 306 deviation, 294 perforation, 294 of nose, arterv, 643, 613, 640 lieiiiorrbage from, (;43 orbitale, 320 Serralus maginis m., 50, 71 Sesamoid cartilages of nose, 293 Seventh cervical n., anterior di- vision, 71, 78 cranial n., 465, 728, 458, 715 origin, 552 Sheath, carotid, 66 contents, 73 Shrapnell's membrane, 419, 418 Sight, second, 396 Sigmoid sinus, 720, 715 course, 592 thromliosis, 423, 511 Silent region of brain, 499 Sinking of eyeball, 357 Sinus ala? i)ar\ le, 724 cavernotis, relation to Gasse- rian ganglion, 725 section. 343 cervicalis, 26 circular, 726, 714, 715 circularis rectii, 471 ethmoid, 315. ]'iile Cells, Ethmoid, frontal, 30-^, 298, 314, 339, 355, 653, 705, 709 congestion. 311 empyema, 311 fractme. 311 polypus, 311 pus, 311 inferior longitudinal, 724, 714 petrosal. 726, 714, 715 lateral, 720, 714, 715 course, 592 divisions, 720 line, 723, 721 operation to expose, 510 thrombosis, 511, 720 tributaries, 720 longitudinal, inferior, 724, 714 superior, 719, 714, 715 course, 592 line, 719 wound, 719 maxillary, 312. Vide An- trum of High more, occipital, 724, 715 of chamber of eve, anterior, 391 of external auditory meatus, 403 of larvnx, 266 of Morgagni, 231, 229 petrosiil, inferior, 726, 714, 715 superior, 726, 715 thrombosis, 723 pvriformis, 237, 248, 218, 236. 250 sigmoid, 715 INDEX. 765 Sinus, sigmoul, conrsp, r>!)2 throiuliosis. I'.>:!, 511 sphenoiil. :>15, 291 sphen()-|Kiiictal, 7"J4 strait;ht, VK. 7J4, 714 SHperiof iDii^ituilinal, 719, 714, 715 I'our.sf, .■>;):.' lino, 71!) wounil. 719 petrosiil, "rUS. 715 transverse, 726, 714. 715 Sinuses, cjiveriions, ~:l'\ 715 of dura mater of Iiraiii, ~\A, 714, 715 lie 111 orrliage from, 719 of frontal l)one, ."lUl Sixth cervical n. , 149 anterior division, 39, 71, 78 cranial n.. :ill. Ifi.i, 728, 326. 339. 343,458,715 Skin of eyelid, 353 / of face, 025 / of neck, 17, 26 of nose, 285 of pinna, 660 of scalp, 602, 599 Skull, arteries, 573 base, dislocation, 579 fracture, 5iS5 blood supply, 617 bones, development, 584 bregma, 573 fontanels, 5S4 fracture, 692, 707 fractures, 584 lambda, 573 sutures, .573 vault, fracture, 585 Slender lobe of cerebellum, 560 Slit, interpaljiebral, 648 Smegma prteputii, 628 Smell, center, 503 Snorin;;;, 637 Socia parotidis, 656, 659, 613, 627 Soft palate, 23^1 Space, crico-thyroid. 24 intercrural, 459 interpef faii:il ii,, GliG fascia. (JH. 620 abst'ess lunieatli, 618 density, (il8 relations, (il.'? fissure, middle, 474, 477 suiwrior, 474 lobe, JHl, lill, 471 inferior surfaee, 494 landmarks, oClU lobes, 4-j(> Ivniphatios, (il.^ iniiscle, (ir>, 321, 621, 678. 686 action, fii) blood supply, 625 ins",*."> nerve supply, 625 ori^tin, (>"J."> nerve, anterior, (UJ, 686 posterior, lil-J, 678 supertieial, 68S iiers'es, deep. 6i^7 region, 6'.'.">. 621 ridges. .")!1'2 vein, 50, 70, 319 middle. 35. 645 superliei:d. 35. 613, 620 645 Teniporo-faeial ii., 6i>i) bniuclies, 609 Temporo-malar n.. 3.'il. 694 Temporo-maxillarv articulation, b7:i. 576. 577 blood supply. .i74 interartieular fibro-carti- lage. ,574 ligaments, .">7:{ ciiwnlar. 576. 577 internal lateral, 574 movements, r-t'-i nerve supply, .■i74 synovial meinlirane, 574 vein, "35 621, 695 Temporo-splienoid abscess, 511 trepbining. 511 convolution, inferior, 495, 494 middle, 492. 494 superior. 4!»2. 494 fissure, inferior. I'.i2. 488, 494. 497 middle. 192. 494 line. 51(1. 506 superior. 492. 494 line. 510. 506 lobe, 4.56, if*\. 191. 458, 565. fide Temporal Lobe, landmarks. ,509 Tendo oculi. .594, 6:i(). 652, 350 l)ali>ebranini, 6I!0 Tendon, central, of perineum, 590 common, of recti miLscle. in- ferior, 347 superior, :i47 Tendon of unio-liynid m,, 39 tensor tympani, 409 Tenon, capsiile, H21. :M2, 320 eajisula. 321 space, :{2I, :!95. 321 Tenotomy in torlieollis, H7 Tensor palati m., 245, 303, 690 action, 245 insertion. 245 origin. 245 tarsim.,63:>, 321.346,355, 632, 653 action, (iol insertion, (iH."} nerve supply, 634 origin. 63:! relations. (>'■)'■'> tympani m.. 42.5, 405, 422 action, 425 in.scrtion, 425 ner\ e supply, 425 origin. 425 tendon. 409 Tenth cranial n.. 76. Iiu:. 458, 542, 556 origin, 552 nerve, 729, 715 Tentorium cerebelli, 4.55, 712, 717, 71S, 714 Terminal biancb of anterior eth- moid a.. I!37 Testes, o4:>, 542, 556, 560 brachia, 541! Tetanus, 231 Thalamus, optic, 526. 53X, 519, 523, 542, 546, 552, 569 puhinar, 539 tubercle, anterior, 538 posterior, 538 Third cervical n.. anterior divis- ion, 71, 78 cranial n., 341, 402,727,326, 458. Title Oculo- motor Nerve, origin, 552 ventricle. .5.32. 516, 528, 529, 536, 556, 569 Thoracic a., lung, 123 sui)eri(jr, 133 duct, 12f<, 100, 129 relations, 131 nerve, external anterior, 149 first, 149 anterior division, 79 internal anterior. 149 ]iosterior. or long, 153, 51, 71, 149 Thrombosis of lateral sinus, 511, 720 of petrosal sinus, superior, 423 of sigmoid sinus, 423, 511 Thyro-ar>tenoid ligaments, supe- rior, 260 Thyro-arytenoidens m., 261, 259 action, 261 insertion, 261 nerve supply, 261 origin, 201 Thyro-epiglottidean ligament, 270 Thyro-epiglottideus m., 261 action, 261 nerve supply, 261 Thyro glo.ssid duct, 125, 216 Thyro-liyoid bursii, 2.55 ligaiMiMit, 2,55, 254, 263 nicinliiane. 2.55, 123, 212, 251, 254, 263 nnisele, 121, 50, 71, 78, 177 action, 121 blood supply, 121 insertion, 121 nerve supply, 121 origin, 121 relation.s, 121 Thyroid a., inferior, (il, 144, 78, 129, 133, 174, 229 anastomosis, 144 branches, 144 irregularities, 179 ligation, 145, 179, 177 line, 20. 67 operations to expose, 174 superior. S6, 50, 70, 78, 105, 123, 133, 177, 251 irregularities, IhH ligation. 1S7, 177 line, 20, 67 axis, 144, 78, 79, 133, 174 branches. 114 body, 39, 78 cartilage, 21!. 273. 123, 251, 254, 258. 259, 271 fracture. 274 ossilieation. 274 gland, 23. 122, 123, 129, 251 arteries, 126 capsule. 126 in tiacbeotoniy, 122 isthmus, 251 nerves, 126 relations, 122 structure, 122 veins, 120 inferior. 78, 79, 123, 164. 251 middle, 35, 70, 645 superior, 91, 35, 70, 645 Thvroidea; inia a., 126, 133 Tli'vroidectomv, 126 Tie c. 35. 50. 51. 70. 645 centr.il, of retina. 360, 384 cerebral superior, 709 cervical, deep, ilU, 117, 35, 645 suiHTlieial, 70 ciliarv. anterior, 379, 369, 377. 384 communieatin^. 70 conjunctival, 384 deep cervical, !)ii. 35. 645 facial. (;s7 external juf;ular. 645 line. 623 facial, 93. 60(1, (144. 35. 50. 70. 613. 620. 621. 645 arterial blood in. 647 conimunieatious. G47 coarse. (147 deep. 7<) innominate. 35. 645 left. 129 ri-lit. 129 internal jugular. 645 tiia.\illarv. 6'^7. 645 jugular, .interior, 'i'.i. 37. 30, 34. 35. 39. 50. 70. 117. 164, 174, 177, 645 external. 3-7. (iO. 30. 34. 35 39. 50 70. 174. 208. 645 j uKulo-ce plialic branch, 23 line, 23, 32, 27. 623 pulsation in. 32 termination of. l* internal. i!l. Hi. 73. 35. 39. 41. 50. 70. 78. 129. 164, 174 645 position, 18 relations. 73 posterior. 30. 35, 50. 70. 208. 645 Vein, jufiular, jKisterior, external, 37 JH ophthalmic, 337. 343 common, 33-'. 334 inferior, 33>', 334 phlebitis, 338 pulsiition, 3,3"* superior. 33'^. 334 orbital. 35. 645 pharyn(;eal, ilescendins, 97 posterior auricular, 35 pudic, internal, 61,i retinal, 381 scapular, posterior. 70 subclavian. 60. 35, 70, 78, 79, 129, 174. 645 submental. 35. 645 superlicial temporal, 620, 645 superior thyroid. 645 supraorbital. 35. 645 su]tra-sca)Milar. 61). 35. 50, 70. 167, 645 temporal, 50, 70, 193 dijiloic, anterior, 707, 705 middle. 35. 645 superlicial. 35, 613, 620. 645 temporo-maxillary, 35, 621, 645 thvroid, inferior, 78. 79, 123 164, 251 middle, 35. 70. 645 su)>erior, 91. 35. 70. 645 transversjdis colli. 60. 35, 50. 70. 645 transverse facial. 35. 645 vertebral. 1 13. 35. 33, 78. 79. 129, 137. 174, 645 Veins, cerebellar. I.'il diploic, 704. 705 frontal, 707, 645 diploic. 7117. 705 fronto-spheuoid. 707, 705 in tracheotomy, 37 meninf;ea'. 73."> of brain, 4.54 of cerebrum, 4.54 of external auditory meatus, 407 of eyeball, 379 of evelids. (i.').") of face. 35. 645 of (ialen. 442. 532, 533, 714 of head, 645 of internal ear, 437 of larynx, 265 Veins of middle ear, 425 of nasjil cavities. 307 of neek. 35. 645 of nose, 2"'5 of orbit, 334 of pharynx, 238 of ptery;;oid plexus, 687 of i)terygoinaxillary renion, 6M7 of scalp, 606, 35, 645 of .scrotum, 644 of tonsils, 225 ptery;;oid plexus, 687 retinal, 3,-<5 thyroid, 126 Velum iuli-i po^ilum. 1.5 1. 531, 488, 497, 516, 533, 546. 569 medullary, posterior, ,562 superior, 543. 516, 536, 542.560. I Vr/, Valve of A'ieus-^ens. Vena aqneductus c