BIOLOGY LIBRARY * SURGICAL APPLIED ANATOMY SURGICAL APPLIED ANATOMY BY SIR FREDERICK TREVES, BART. G.G.V.O., G.B., LL.JK, F.R.G.S. Eng. Serjeant Surgeon to H.M. the King; Consulting Surgeon to the London Hospital ; late Lecturer on Anatomy at the London Hospital SEVENTH EDITION, REVISED BY ARTHUR KEITH, M.D., LL.D. Aber., F.R.G.S. Eng., F.R.S. Hunterian Professor and Conservator of the Museum, Royal College of Surgeons of England ; formerly Lecturer on and Senior Demonstrator of Anatomy at the London Hospital ; Examiner in the Universities of Aberdeen, Cambridge, etc. W. COLIN MACKENZIE, M.D. Melb., F.R.C.S. Edin., F.R.S.E. Member of Council of the Anatomical jsoqi^ty of Great Britain and Ire^an^ > formerly Lecturtr . on Applied Anatomy 1 , rjnJvprsfay of Melhq-irfke ILLUSTRATED WITH' i53 FIGURES INCLUDING 74 IN COLOUR LEA & FEBIGER Philadelphia and New York l^ O 1 \\\ PREFACE TO THE SEVENTH EDITION ALTHOUGH many additions have been made to and minor alterations effected in the present edition, this book still retains the spirit, form, and size given to it by its distinguished author. Every chapter has been revised in the light of recent surgical experience and progress. War has an influence even on such a manual as this, and yet, when we came to consider how far the experience of our Military Surgeons in the Field necessitated modifications of the text, we found that Sir Frederick Treves had already antici- pated most of our modern needs. We have added considerably to what may be called "orthopaedic anatomy " the kind of knowledge which is neces- sary for the successful treatment of stiffened joints and disabled limbs. Twenty-seven new illustrations have been introduced. We intended to apply, as far as was possible, the new Anatomical Nomenclature, but the further we proceeded with its application the more we felt that we should do British Anatomy and Surgery an ill service were we to abandon a tried and convenient system for one which, in many respects, is clumsy and imperfect. What we have done is to insert the new names side by side with the old (some of the new terms being advantageous), so that those who prefer the new nomenclature may still read a book which has been used so widely by a long succession of students and practitioners. A. K. W. C. M. The Museum, Royal College of Surgeons of England. December, 1917. PREFACE TO THE FIRST EDITION APPLIED ANATOMY has, I imagine, a twofold func- tion. On the one hand it serves to give a precise basis to those incidents and procedures in practice that more especially involve anatomical knowledge; on the other hand it endues the dull items of that knowledge with meaning and interest by the aid of illustrations drawn from common medical and surgical experience. In this latter aspect it bears somewhat the same relation to Systematic Anatomy that a series of experiments in Physics bears to a treatise dealing with the bare data of that science. The student of Human Anatomy has often a nebulous notion that what he is learning will some time prove of service to him ; and may be conscious also that the study is a valuable, if somewhat unexciting, mental exercise. Beyond these impressions he. must regard his efforts as concerned merely in the accumulation of a number of hard, unassimilable facts. It should be one object of Applied Anatomy to invest these facts with the interest derived from an association with the circumstances of daily life; it should make the dry bones live. It must be owned also that all details in Anatomy have not the same practical value, and that the memory of many of them may fade with- out loss to the competency of the practitioner in medicine or surgery. It should be one other object, therefore, of a book having such a purpose as the present, to assist the student in judging of the comparative value of the mia^ter he has viii PREFACE learnt; and should help him, when his recollection of anatomical facts grows dim, to encourage the survival of the fittest. In writing this manual I have endeavoured, so far as the space at my command would permit, to carry out the objects above described; and while I believe that the chief matters usually dealt with in works on Surgical Anatomy have not been neglected, I have nevertheless tried to make the principle of the book the principle that underlies Mr. Hilton's familiar lectures on "Rest and Pain." I have assumed that the reader has some know- ledge of Human Anatomy, and have not entered, except in a few instances, into any detailed anatomical descriptions. The bare accounts, for example, of the regions concerned in Hernia I have left to the systematic treatises, and have dealt only with the bearings of the anatomy of the parts upon the circumstances of practice. The limits of space have compelled me to omit all those parts of the "Surgery of the Arteries ' that deal with ligature, collateral circulation, abnormalities, and the like. This omission I do not regret, since these subjects are fully treated not only in works on operative surgery, but also in the manuals of general anatomy. The book is intended mainly for the use of students preparing for their final examination in surgery. I hope, however, that it will be of use also to practitioners whose memory of their dissecting-room work is growing a little grey, and who would wish to recall such anatomical matters as have the most direct bearing upon the details of practice. Moreover, it is possible that junior students may find some interest in the volume, and may have their studies rendered more in- telligent by learning how anatomy is concerned in actual dealings with disease. FREDERICK TREVES. September, 1883. CONTENTS PART I.-THE HEAD AND NECK CHAPTER PAGW 1. THE SCALP i 2. THE BONY VAULT OF THE CRANIUM ... 17 3. THE CRANIAL CONTENTS 34 4. THE ORBIT AND EYE 55 5. THE EAR ..... . . . . 87 6. THE NOSE AND NASAL CAVITIES .... 105 7. THE FACE . . . . . . . .121 8. THE MOUTH, TONGUE. PALATE, AND PHARYNX . 150 9. THE NECK 173 PART IL THE THORAX 10. THE CHEST AND ITS VISCERA .... 212 PART HL THE UPPER EXTREMITY 11. THE REGION OF THE SHOULDER .... 236 12. THE ARM . 275 13. THE REGION OF THE ELBOW .... 283 14. THE FOREARM . 301 15. THE WRIST AND HAND 310 16. THE NERVE SUPPLY OF THE UPPER EXTREMITY 335 x . CONTENTS PART IV.-THE ABDOMEN AND THE PELVIS OKAPTHB PAGK 17. THE ABDOMEN . 347 18. THE PERITONEUM AND ALIMENTARY TRACT . 386 19. THE OTHER ABDOMINAL VISCERA . . . 432 20. THE PELVIS AND PELVIC VISCERA . . .465 21. THE PERINEUM 475 PART V. THE LOWER EXTREMITY 22. THE REGION OF THE HIP 523 23. THE THIGH 561 24. THE REGION OF THE KNEE 569 25. THE LEG . .596 26. THE ANKLE AND THE FOOT 607 PART VL-THE SPINE AND SPINAL CORD 27. THE SPINE 647 28. THE SPINAL CORD .659 INDEX . 675 SURGICAL APPLIED ANATOMY P ART I.THE HEAD AND NECK CHAPTER I THE SCALP THE soft parts covering: the vault of the skull may be divided into five layers : (1) the skin, (2) the subcutaneous fatty tissue, (3) the occipito-frontalis or epicranial muscle and its aponeurosis, (4) the subepicranial connective tissue, and (5) the pericranium. It is convenient to consider the term " scalj) " as limited to the structure formed by the union of the first three layers above named (Fig. 1). The skin of the scalp is thicker than in any other part of the body. It is in all parts in- timately adherent, by means of the subcutaneous tissue, to the aponeurosis and muscle beneath it, and, from this adhesion, it follows that the skin moves in all movements of that muscle. The sub- cutaneous tissue is, like a similar tissue in the pahn, admirably constructed to resist pressure, being composed of a multitude of fibrous bands enclosing fat lobules in more or less isolated spaces (Fig. 1, 6). The density of the scalp is such, that in surface inflammations, such as cutaneous ery- sipelas, it is unable to offer (except in a very slight degree) two conspicuous features of such inflammations, viz. redness and swelling. The skin THE HEAD AND* NECK [CHAP. is projected wJtii ;a/ieit number of glandsj which may* develoiKinl o cystic t * sebaceous tumours or wejnrs sjU.iIgygtf & TjIwiginAre* common upon the scalp tha'rf'in* any 'other : ptf^* of the body. Being skin growths, these cysts, even when large, remain, ex- -ct -I -c -cl ~e f Fig. 1. Diagram showing the layers of the scalp and membranes of the brain in section. a, Skin ; b, subcutaneous tissue with hair roots and vessels : <, epi- cranius ; d, subepicranial layer ; e, pericranium ; /', parietal bone ; g, dura mater ; it, arachnoid ; I, pia mater ; m, cortex ; n, in subdural space near a Pacchionian body projecting within the superior longitudinal sinus, cept in rare instances, entirely outside the epi- cranius, and can therefore be removed without risk of opening up the area of loose connective tissue between the epicranial fascia and the peri- cranium. There being no fatty tissue in any of the layers that cover the bony vault save in the subcutaneous i] THE SCALP layer, it happens that in cases of obesity the scalp undergoes but little change, the fat in the subcu- taneous tissue being limited by the dense fibrous structures that enclose it. For the same reasons fatty tumours of the scalp are very rare. The attachment of the hairs collectively to the scalp is so strong that there are many cases where the entire weight of the body has been supported by the hair of the scalp. Agnew records the case of a woman whose hair became entangled in the re- volving shaft of a machine. The hair did not give way, but the entire scalp was torn off from the skull. The patient recovered Dangerous area of the scalp. Between the epicranius and the pericranium is an exten- sive layer of loose connective tissue, that may, for reasons to be presently 'given, be fairly called the dangerous area of the scalp (Fig. 1, d). The mobility of the scalp depends entirely upon the laxity of this layer of tissue. In extensive scalp wounds, when a part of the scalp is separated in the form of a large flap, a flap that may hang down and cover half the face, it is the very loose- ness of this tissue that permits such separation. The exposure of the skull in a post-mortem examination is effected by peeling off the scalp along this layer of loose tissue, and it is remark- able with what ease the skull can be exposed by this manoeuvre. Wound* of the scalp never gape, unless the wound has involved the scalp muscle or its apo- neurosis. When this structure has been divided the lax layer beyond permits of great separation of the edges of ^even the simplest wounds. In uncom- plicated incised wounds, the amount of gaping of the cut depends upon the action of the epicranius or occipito-frontalis muscle. Those wounds gape the most that are made across the muscle itself, and that are transverse to the direction of its fibres, while those show the least separation that involve the aponeurosis and are made in an antero- posterior direction. The mobility of the scalp is 4 THE HEAD AND NECK [CHAP. more marked in the young than in the old. A case recorded by Agnew serves in a strange degree to illustrate this fact in the person of an infant. A midwife attending a woman in labour mistook the scalp of the infant for the membranes, and gashed it with a pair of scissors. Labour pains came on and the head was protruded through the scalp wound, so that the whole vault of the skull was peeled like an orange. The scalp being firmly stretched over the hard cranium beneath, it follows that contused wounds often appear as cleanly cut as are those that have been made by an incision. Such wounds may be compared to the clean cut that may be made in a kid glove when it is tightly stretched over the knuckles and those parts are sharply rapped. The scalp is extremely vascular, and presents therefore a great resistance to sloughing and gan- grenous conditions. Large flaps of a lacerated scalp, even when extensively separated and almost cut off from the rest of the head, are more prone to live than to die. A like flap of skin, separated from other parts of the surface, would most prob- ably perish ; but the scalp has this advantage, that the vessels run practically in the skin itself, or are, at least, in the tissue beyond the aponeurosis (Fig. 1). Thus, when a scalp flap is torn up, it still carries with it a very copious blood supply. Bleeding from these wounds is usually very free, and often difficult to arrest. This depends not so much upon the number of vessels in the part as upon the density of the tissue through which these vessels run, the adherence of the outer arterial wall to the scalp structure, and the inability, therefore, of the artery to retract properly when divided. For the same reason it is almost im- possible to pick up an artery divided in a scalp wound. The bleeding is checked by a hare-lip pin or by pressure. In all parts of the body where a dense bone is covered by a comparatively thin layer of soft tissues, sloughing of those tissues is apt to be ij THE PERICRANIUM 5 induced by long and severe pressure. The scalp, by its yascularity, is saved to a great extent from this evil, and is much less liable to slough than are the soft parts covering such bones as the con- dyles of the humerus or the sacrum. But such an effect is sometimes produced, as in a case I (F. T.) saw, where the tissues over the frontal and occipital regions sloughed from the continued application of a tight bandage put on to arrest bleeding from a frontal wound. The pericranium is but slightly adherent to the bone, except at the sutures, where it is inti- mately united (Fig. 1, e). In lacerated wounds this membrane can be readily stripped from the skull, and often, in these injuries, extensive tracts of bone are laid bare. The pericranium differs somewhat in its functions from the periosteum that covers other bones. If the periosteum be removed to any extent from a bone, the under- lying laminae will very probably perish, and necrosis from deficient blood supply result. But the pericranium may be stripped off a con- siderable part of the skull vault without any necrosis, save perhaps a little superficial ex- foliation. This is explained by the fact that the cranial bones derive their blood supply mainly from the dura mater, and are therefore to a considerable extent independent of the pericranium. A like independence cannot be claimed for the periosteum covering other bones, since that membrane brings to the part it covers a very copious and essential contribution to its blood supply. This disposition of the pericran- ium is also well illustrated by its action in cases of necrosis of the cranial bones. In necrosis of a long bone, the separation of the sequestrum is attended with a vigorous periosteal growth of new bone, which repairs the gap left after the re- moval of such sequestra. In necrosis of the vault of the skull, however, no new bone is formed, as a rule, and the gap remains unrepaired. The general indisposition of the pericranium to form 6 THE HEAD AND NECK [CHAP new bone in other circumstances is frequently illustrated. Abscesses in the scalp region may be situated (1) above the epicranial aponeurosis, (2) between the aponeurosis and the pericranium, and (3) beneath the pericranium. Abscesses in the first situation must always be small and comparatively insignifi- cant, since the density of the scalp tissue here is such that suppuration can only extend with the greatest difficulty. Suppuration, however, in the second situation (in the loose tissue beneath the aponeurosis) may prove very serious. The laxity of this tissue offers every inducement to the ab- scess to extend when once pus has found its way between the aponeurosis and the pericranium. Suppuration in this area may undermine the en- tire scalp, which in severe and unrelieved cases may rest upon the abscess beneath as upon a kind of water-bed. As in scalp wounds, the aponeu- rosis is often divided, and as suppuration may follow the injury, it will be seen that the chief danger of those lesions depends upon the spread- ing of such suppuration to the area of lax con- nective tissue now under notice. The significance of a small amount of bare bone in a scalp wound is not so much that evils will happen to the bone as that the aponeurosis has been certainly divided and the dangerous area of the scalp opened up. Suppuration, when it occurs in this area, is only limited by the attachments ^of the occipito-frontalis muscle and its aponeurosis, and therefore the most dependent places through which pus can be evacuated are situated along a line drawn round the head, commencing in front, above the eyebrow, passing at the side a little above the zygoma, and ending behind at the superior curved line of the occipital bone. The scalp, even when extensively dissected up by such abscesses, does not perish, since it carries, as above explained, its blood supply with it. The abscess is often very slow to close, since its walls are prevented from obtaining perfect rest by the frequent movement i] H.EMATOMATA OF THE SGALP 7 of the epicranial muscle. To mitigate this evil, and to ensure closing of the sinuses in obstinate cases, Hilton advises that the whole scalp be firmly secured by strapping, so that the movement of the muscle is arrested. Abscesses beneath the pericranium must be limited to one bone, since the dipping-in of the membrane at the sutures prevents a more exten- sive spreading of the suppuration. Hrematomata, or blood tumours, of the scalp region occur in the same localities as ab- scesses. The extravasation of blood above the apo- neurosis must be of a limited character, while that beneath it may be very extensive. It fortunately happens, however, that the cellular tissue between the aponeurosis and the pericranium contains but very few vessels, and hence large extravasations in this tissue are uncommon. Extravasations of blood beneath the peri- cranium are generally termed cephalhsematomata, and are of necessity limited to one bone. They are usually due to pressure upon the head at birth, and are thus most commonly found over one parietal bone, that bone being probably the one most exposed to pressure. Their greater fre- quency in male children may depend upon the larger size of the head in the male foetus. Such extravasations in early life are encouraged by the laxity of the pericranium, and by the softness and vascularity of the subjacent bone. In the temporal region, or the region corre- sponding to the temporal muscle, the layers of soft parts between the skin and the bone are some- what different from those that have been already described as common to the chief parts of the scalp. There is a good deal of fat in the temporal fossa, and when this is absorbed it leads to more or less prominence of the zygoma and malar bone, and so produces the projecting "cheek bones" of the emaciated. The temporal muscle above the zy- goma is covered in by a very dense fascia, the temporal fascia, which is attached above to the 8 THE HEAD AND NEGK [CHAP. temporal ridge on the frontal and parietal bones, and below to the zygomatic arch. The unyielding nature of this fascia is well illustrated by a case recorded by Denonvilliers. It concerned a woman who had fallen in the street, and was ad- mitted into hospital with a deep wound in the temporal region. A piece of bone of 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 con- sidered to be one of compound fracture of the squamous bone, with separation of a fragment and exposure of the brain. A bystander, however, noticed that the bone removed was dry and white, and a more complete examination of the wound revealed the fact that the skull was uninjured, that the supposed 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. Abscesses in the temporal fossa are prevented by the fascia from opening anywhere above the zygoma, and are encouraged rather to spread into the pterygoid and maxillary regions and into the neck. The pericranium is much more adherent to the bone in the temporal region than it is over the rest of the vault, and subpericranial extrava- sations of blood are therefore practically unknown in this part of the cranial wall. Vessels and nerves of the scalp. The supraorbital artery and nerve pass vertically up- wards from the supraorbital notch, which is situ- ate at the junction of the middle with the inner third of the upper orbital margin. Nearer the middle line the frontal artery and supratrochlear nerve ascend. This artery gives life to the flap that in rhinoplasty is taken from the forehead to form a new nose. The temporal artery, with i] VESSELS OF THE SCALP 9 the auriculo-temporal nerve behind it, crosses the base of the zygoma just in front of the ear. The vessel divides into its two terminal branches (the anterior and posterior) 2 inches above the zygoma. The branches of this artery, especially the an- terior branch, are often very tortuous in the aged, and afford early evidence of arterial degeneration. Arteriotomy is sometimes practised on the an- terior branch of this vessel. The superficial tem- poral vessels are very liable to be the seat of cirsoid aneurysm, as, to a less extent, are the other scalp arteries. The posterior auricular artery and nerve run in the groove between the mastoid process and the ear, and the occipital artery and the great occipital nerve reach the scalp just internally to a point midway between the occi- pital protuberance and the mastoid process. Certain of the emissary veins are of import- ance in surgery. These veins pass through aper- tures in the cranial wall, and establish communi- cations between the venous circulation (the sinuses) within the skull and the superficial veins external to it. The principal emissary veins are the following : 1. A vein passing through the mas- toid foramen and connecting the lateral sinus with the posterior auricular vein or with an occi- pital vein. This is the largest and most constant of the series. The existence of this mastoid vein serves to answer the question, Why is it a com- mon practice to apply leeches and blisters behind the ear in certain cerebral affections 1 2. A vein connecting the superior longitudinal sinus with the veins of the scalp through the parietal foramen. 3. A vein connecting the lateral sinus with the deep veins at the back of the neck through the posterior condylic foramen (inconstant). 4. Minute veins following the twelfth nerve through the anterior condylic foramen, and connecting the occipital sinus with the deep veins of the neck. 5. Minute veins passing through the foramen ovale, foramen of Vesalius, foramen lacerum medium, and carotid canal, to connect the cavern- 10 THE HEAD AND NECK [CHAP. ous sinus with (respectively) the pterygoid venous plexus, the pharyngeal plexus, and the internal jugular vein. Then, again, many minute veins connect the veins of the scalp with those of the diploe. Of the four diploic veins, two (the frontal and anterior temporal) enter into surface veins (the supra- orbital and deep temporal), and two (the pos- terior temporal and occipital) enter into the lateral sinus. Lastly, there is the well-known communication between the extra- and intracranial venous circu- lation effected by t^e commencement of the facial vein at the inner angle of the orbit. In this com- munication the angular and supraorbital veins unite with the superior ophthalmic vein, a tribu- tary of the cavernous sinus. The veins within the cavities of the nose and middle ear also communi- cate with those of the meninges. Through these various channels, and through many probably still less conspicuous, inflammatory processes can spread from the surface to the in- terior of the skull. Thus we find such affections as erysipelas of the scalp, diffuse suppuration of the scalp, necrosis of the cranial bones, and the like, leading by extension to mischief within the diploe, to thrombosis of the sinuses, and to inflammation of the meninges of the brain. If there were no emissary veins, injuries and diseases of the scalp and skull would lose half their seriousness. Mis- chief may even spread from within outwiards along an emissary vein. Erichsen reports a case where the lateral sinus was exposed in a compound frac- ture. The aperture was plugged. Thrombosis and suppuration within the sinus followed, and some of the pus, escaping through the mastoid vein, led to an abscess in the neck. Certain venous tumours are met with on the skull. They consist of collections of venous blood under the pericranium that communicate, through holes in the skull, with the superior longitudinal sinus. They are median, are reducible on pressure, i] VENOUS TUMOURS ON THE SKULL 11 and receive a faint pulsation from the brain. The holes are sometimes the result of accident, others depend upon bone disease or atrophy over a Pac- chionian body, and a few are due to a varicose emissary vein or to a congenital defect in the Fig. 2. Nerve areas of the face and scalp. A, A, Distribution of the first division of the fifth cranial nerve: A , nasal branch ; A", supratrochlear ; A'", supraorbital. B, B, Distribution of the second division : B', infraorbital branch ; B", malar branch ; B'", temporal branch. C, C, Distribution of third division : c', mental branch ; C , buccal branch ; C'", auriculo-temporal. 1, Area of great occipital ; 2, of small occipital ; 3, of great auricular ; 4, of superficial cervical ; 5 of third occipital. cranium, especially in the neighbourhood of the parietal foramina. 12 THE HEAD AND NECK [CHAP. The scalp nerves, especially such as are branches of the fifth pair, are often the seat of neuralgia (Fig. 2). To relieve one form of this affection, the supraorbital nerve has been divided (neurotomy), or paralysed by an injection of absolute alcohol at its point of exit from the orbit. Some forms of frontal headache depend upon neuralgia of this nerve. The inner or medial branch of the nerve reaches the middle of the parietal bone ; the outer branch, the lambdoid suture. The lymphatics from the occipital and posterior parietal regions of the scalp enter the occipi- tal and mastoid glands; those from the frontal and anterior parietal regions go to the parotid glands, while some of the vessels from the frontal region join the lymphatics of the face and end in the submaxillary glands (Fig. 50, p. 207). Trephining. This operation is one of the oldest in surgery. We know that it was exten- sively practised in France more than six thousand years ago, for skulls of that period show un- mistakable signs of having been successfully trephined. At the present day this operation is frequently performed in the temporal region, one object being to reach extravasations of blood from the middle meningeal veins or artery. These vessels cross the anterior inferior or sphenoidal angle of the parietal bone at a point 1^ inches behind the malar or external angular process of the frontal bone, and li inches above the zygoma. In cutting down to expose these vessels the following structures are met with in order : (1) The skin ; (2) branches of the superficial tem- poral vessels and nerves; (3) the fascia continued down from the epicranial aponeurosis; (4) the temporal fascia ; (5) the temporal muscle ; (6) the deep temporal vessels; (7) the pericranium; (8) the sphenoidal angle of the parietal bone. Trephining: for meningeal haemorrhage and cerebral abscess. -At the sphenoidal angle of the parietal bone the anterior division of the middle meningeal artery lies with its companion veins I] TREPHINING 13 in a deep groove or even canal in the bone. A fracture of the bone, which is comparatively thin in the region of the pterion, is almost certain to rupture the veins, and may also involve the artery, leading to a subdural haemorrhage, with consequent compression of the brain. The pterion lies 1-| inches behind and ^ an inch above the notch of the fronto-malar (fronto-zygomatic) suture a BR.CCJAIA .COROA1AL5UTUR& SUP. TEM. LIME EXT AUDITOR OCCIPITAL AR.T IftT JUQULAH VEIrt EXT CAROTID ART Fig. 3. Points to trephine for middle meningeal vessels and lateral sinus. point which can be readily felt (Fig. 3). Similar measurements namely, lj inches behind and \ an inch above taken from the centre of the external auditory meatus the meatal point, give the posi- tion of the posterior inferior angle of the parietal bone (asterion), beneath which lies the highest point of the lateral sinus (Fig. 3). A trephine opening, f of an inch in diameter, made over the asterion, will expose the lateral sinus, and give access to the temporo-sphenoidal lobe above it 14 THE HEAD AND NECK [CHAP. and to the cerebellum below it. The posterior division of .the middle meningeal, in the majority of cases, will be exposed by trephining at a point 1 inch above the external auditory meatus. These measurements apply to the head of the average adult; allowance must be made for youth and for the size and shape of the head. In finding the pterion, a line is drawn backwards parallel to the upper border of the zygoma; in finding the asterion, a line is drawn backwards along the meato-inionic line (Fig. 3), which passes from the centre of the external meatus to the most promi- nent point of the external occipital protuberance the inion. It may also be necessary to trephine for an abscess of the temporal lobe, the pus being usually found in that part of the lobe which lies over the tegmen tympani a thin plate of bone which forms the roof of the tympanum and of the antrum of the mastoid. The level of the tegmen may be indicated thus (Fig. 4) : A point is taken above the meatus in line with the upper border of the zygoma; this suprameatal point is joined with the asterion, which lies, it will be remem- bered, 1^ inches behind and ^ an inch above the meatus; the anterior half of the above line corre- sponds to the tegmen tympani. A trephine open- ing made 1 inch above the level of the tegmen is the most likely to give access to an abscess situated in the temporal lobe In dealing with an abscess of the cerebellum the best spot to select is, in the adult, 1^ inches behind the centre of the meatus and J of an inch below the meato-inionic line. In some cases it is impossible to say whether the abscess is situated in the temporal lobe or the cerebellum. In such cases trephining should be performed at a point which lies 1 finches behind and \ of an inch above the centre of the meatus. The lateral sinus is thus exposed with a part of the dura mater above the tentorium_ cerebelli, through which the temporal lobe may "be explored. By extending TREPHINING 15 the trephine opening | an inch downwards the cerebellum may be examined. Trephining for cerebral tumour. The position of the opening in the skull is obviously determined by the localizing symptoms. It is remarkable that little trouble from haemorrhage has attended these operations. In any case, after trephining, the portion or portions of bone removed may if properly treated be replaced in the opening, and will FRONTAL POLE ANTERIOR noun flSSUREor SYLVIUS UPPER ROLANDO POINT FISSURE OF ROLANDO PARIETAL EMINENCE PARIETO OCCIPITALFISSURI LAMBDA FOR LATERAL VENTRICLE- POST. hoa.n DESC.MORAI FOR TEMP-SPEN. ABSCESS OCCIPITAL POLE ON CEREBELLUM ASTERIOM TYMPANIC PLATE 5llPRAMEATAL TRIANCLE 'AIE.ATUS SuPRANEATAL POINT , Fig. 4. Diagram to show the position of the lateral ven- tricles, the insula (island of Reil), and the temporal pole. serve, especially in youthful subjects, to make food the gap left by the operation. The ostep- lasts in the fragments remain alive and retain the power of bone-formation. In trephining the skull, the comparative thick- ness of the cranial wall in various parts should be borne in mind, and the large arteries of the scalp should, if possible, be avoided. In order to accommodate the instrument to the varying thickness of the skull, the pin of the trephine is not allowed to protrude more than & of an inch. In the temporal fossa the bone varies in 16 THE HEAD AND NECK thickness from 2 to 5 mm. (A to I of an inch). In the vault the bony wall is thicker, varying from 5 to 10 mm. ( to f of an inch). (See p. 30.) The zygoma may be broken by direct or in- direct violence. In the latter case the violence is such as tends to thrust the upper jaw or malar bone backwards. When due to direct violence, a fragment may be driven into the temporal muscle, and much pain caused in moving the jaw. In ordinary cases there is little or no displacement, since to both fragments the temporal fascia is attached above and the masseter below. The zy- goma serves as a most useful guide to the position of deep parts. Its upper border, in its posterior three-fourths, corresponds to the floor of the mid- dle fossa of the skull, and marks the lower border of the temporal lobe of the brain which lies in that fossa (Fig. 4) ; the articular tubercle, felt so plainly near its root, marks the point at which the middle meningeal artery perforates the base of the skull by the foramen spinosum (Fig. 3), and also the position of the semilunar or Gasserian ganglion (Fig. 32, p. 131) ; the zygomatic tubercle (postglenoid spine), which bounds the mandibular fossa posteriorly, is directly over the carotid canal (S. Scott). CHAPTER II THE BONY VAULT OF THE CRANIUM Position of the sutures. The bregma, or point of junction of the coronal and sagittal sutures, is in a line drawn vertically upwards from a point just in front of the external auditory meatus, the head being in normal position (Fig. 3). The lambda, or point of junction of the lambdoid and sagittal sutures, lies in the middle line, about 2j- inches above the occipital protuberance (Fig. 3). The lambdoid suture is fairly represented by the upper two-thirds of a line drawn from the lambda to the apex of the mastoid process on either side. The coronal suture lies along a line drawn from the bregma to the middle of the zygomatic arch. On this line, at a spot about 1^ inches behind and ^ an inch above the fronto-malar (fronto- zygomatic) junction, is the pterion, the region where four bones meet, viz. the squama of the temporal, the great wing of the sphenoid, the frontal and parietal bones (Fig. 3). The summit of the squamous suture is If inches above the zygoma. In the normal subject all traces of the fou- taiielles and other unossified parts of the skull (Fig. 6) disappear before the age of 2 years. The frontal or anterior fontanelle is the last to close, while the occipital or posterior is already filled at the time of birth. It is through or near the frontal fontanelle that the ventricles are usually aspirated in cases of hydrocephalus. The needle is either entered at the sides of the fontanelle at a sufficient distance from the middle line to avoid the longitudinal sinus, or is introduced 17 18 THE HEAD AND NECK [CHAP. through the coronal suture at some spot other than its middle point. It may be noted that in severe hydrocephalus the coronal and other sutures of the vault are widely opened. The condition known as craiiiotabes, a con- dition assigned by some to rickets and by others to inherited syphilis, is usually met with in the upper or tabular part of the occipital bone, and in the adjacent parts of the parietal bones, but especially in the posterior inferior angles of these bones. In this condition the bone is greatly thinned in spots, and its tissue so reduced that the affected district feels to the finger as if occupied by parchment, or, as some suggest, by cartridge paper. The thinning is mainly at the expense of the inner table and diploe. The pits are situated over the impressions of early-formed convolutions. It is, on the other hand, about the site of the frontal or anterior fontanelle that cer- tain osseous deposits are met with on the surface of the skull in some cases of hereditary syphilis (Parrot). These deposits appear as rounded ele- vations of porous bone situated upon the frontal and parietal bones, where they meet in the middle line. The bosses are separated by a crucial de- pression represented by the frontal and sagittal sutures on the one hand and the coronal suture on the other. They have been termed " natiform " elevations by M. Parrot from their supposed resem- blance, when viewed collectively, to the nates. To the English mind they would rather suggest the outlines of a "hot-cross bun." It is necessary to refer to the development of the skull, in order to render intelligible certain conditions (for the most part those of congenital malformation) that are not infrequently met with. Speaking generally, it may be said that the base of the skull is developed in cartilage, and the vault in membrane. The parts actually formed in mem- brane are represented in the completed skull by the frontal and parietal bones, the squamo-zygo- matic part of the temporal bone, and the greater n] MENINGOGELE 19 part of the tabular portion of the occipital bone. The distinction between these two parts of the skull is often rendered very marked by disease. Thus there are, in the museum of the Royal College of Surgeons, the skulls of some young lions that were born in a menagerie, and that, in consequence of malnutrition, developed certain changes in their bones.. A great part of each of these skulls shows considerable thickening, the bone being con- verted into a porous structure ; and it is remark- able to note that these changes are limited to such parts of the skull as are formed in membrane, the base remaining free. In hydrocephaly it is only the bones formed in membrane which are unduly expanded. On the other hand, in the condition known as achondroplasia the basal or cartilaginous parts of the skull are strangely arrested in their growth, while there is a compensatory overgrowth of the membrane-formed elements. Among the more common of the gross malforma- tions of the skull also is one that shows entire absence of all that part of the cranium that is formed in membrane, while the base, or cartila- ginous part, is more or less perfectly developed the condition of anencephaly. Meningocele is the name given to a con- genital tumour that consists of a protrusion of a part of the cerebral membranes through a gap in an imperfectly developed skull. When the protrusion contains brain, it is called an encephalocele; and when that protruded brain is distended by an accumulation of fluid within the ventricles, it is called hydrencephalocele. These protrusions are most often met with in the occipital bone, and next in frequency in the fronto-nasal suture, while in rarer cases they have been met with in the lambdoid, sagittal, and other sutures, and have projected through normal and abnormal fissures at the base of the skull into the orbit, nose, and mouth. Their frequency in the occipital bone may be in some degree explained by a refer- 20 THE HEAD AND NECK [CHAP. ence to the development of that part. This bone at birth consists of four separate parts (Fig. 5), a basilar, two condylic, and a tabular or expanded part. In the tabular part, about the seventh week of foetal life four nuclei appear, an upper and a lower pair. ^E^fiK^k^ These nuclei are to some extent separated by fissures running inwards from the four angles of the bone to meet at the occipital protuberance. The gap running up in the median line from the inferior angle at the foramen magnum to the occipital protuberance is especially distinct (the tem- porary occipital fontanelle of Sutton). It exists from the beginning of the third to the Fig. 5. The occi- end of the fourth month of pital bone at birth, intra-uterine life. Meningo- celes of the occiput are always in the middle line, and the protrusion probably occurs through this gap. The gap associ- ated with meningocele may extend through the whole vertical length, of the occipital bone, and very commonly opens up the foramen magnum. The lateral or transverse fissures divide the bone into two parts. The upper part is developed from membrane, the lower part from cartilage. The lateral fissures may persist, and may simulate frac- tures, for which they have, indeed, been mistaken ; as a rare anomaly they may be so complete as entirely to separate the highest part of the occipital bone from the remainder. Parietal fissures In the developing parie- tal bone, fibres concerned in ossification radiate towards the periphery from two nuclei about the centre of the bone. An interfibrillar space, larger than the rest, is seen about the fifth month to separate the loose osseous fibres which abut on the posterior part of the sagittal border from the II] SUTURAL BONES stronger fibres which form the rest of this border (Pozzi). This is the parietal fissure. It usually closes and leaves no trace, but it may persist in part as a suture-like fissure, and be mistaken for a fracture. If the fissure persists equally on the two sides an elongated lozenge-shaped gap is left, the sagittal fontanelle (Fig. 6). It is situate about an inch in front of the lambda, and occurs in over 4 per cent, of newly born children (Lea). The parietal foramina are remains of this interval. Suf ural or Wormian bones. These irregu- lar bones may be mistaken for fragments produced by fracture. They are most usually met with in the lambdoid suture. One sutural bone deserves special notice, as it may be met with in trephining over the middle meningeal artery. It exists be- /IETOPIC SUTURE __ FRONTAL EMINENCE ..BREQMATIC Fb/ITANELLE ..CORONAL SUTUR& ...SAQITTAL SUTURE ..PARIETAL _ 5AC I TTA L fO/1 TAM E LLE -..UMBDOIDALfO/ITArtELLE .I/ITER-PARIETAL 5UPRA-OCCIPITAL Fig. 6. Skull of newly born child, from above. tween the anterior inferior angle of the parietal bone and the great wing of the sphenoid. It is scale-like, and gives the impression that the tip of the great wing has been separated. It is known as the epipteric bone. Wecrosis is fairly common on the vault of the skull, and most often attacks the frontal and parietal bones, while, for reasons that 22 THE HEAD AND NECK [CHAP. are not very obvious, it is rare in the occi- pital bone. The external table is frequently necrosed alone, it being more exposed to injury and less amply supplied with blood than is the internal table. From the converse of these reasons it happens that necrosis of the internal table alone is but rarely met with. Necrosis in- volving the entire thickness of the bone may prove very extensive, and in a case reported by Saviard practically the whole of the cranial vault necrosed and came away. The patient was a woman, and the primary cause of the mischief was a fall upon the head when drunk. Necrosis of the skull, as well as caries of the part, is attended by certain special dangers that de- pend upon the anatomical relations of the cranial bones. Thus, when the whole thickness of the skull is involved by disease, or when the inner table is especially attacked, a collection of pus may form between the dura mater and the affected bone, and may produce compression of the brain. When the diploic tissue is implicated, the veins of that part may become thrombosed, or may be the seat of a suppurative phlebitis. The mischief thus com- menced may spread, the great intracranial sinuses may be closed by thrombus, or septic matter may be conveyed into the general circulation and lead to the development of pyaemia. Mere local extension may also cause meningitis. In cases of necrosis of the external table the growth of granulation tissue from the exposed and vascu- lar diploe p^lays a very important part in aiding the exfoliation of the lamella of dead bone. Fractures of the skull. It is not easy ac- tually to fracture the skull of a young infant. The skull as a whole at this age is imperfectly ossified, the sutures are wide, and between the bones there is much cartilage and membrane. Moreover, the bones themselves in early life are elastic, and com- paratively soft and yielding. If a blow be inflicted upon the vault in a young child the most probable effect, so far as the bone itself is concerned, is an n] FRACTURES OF THE SKULL 23 indenting or bulging-in of that bone unassociated with a fracture in the ordinary sense. In this par- ticular relation the skull of an infant is to that of an old man as a cranium of thin tin would be to a cranium of strong earthenware. The yielding char- acter of the young child's skull is well illustrated by the gross deformity of the head that certain Indian tribes produce in their offspring by apply- ing tight bandages to the part in infancy. In the Royal College of Surgeons museum are many skulls of" flat-headed JJ In.dians, that show to what an extreme this artificial deformity may be carried. Gueniot also asserts that much deformity of the head may be produced in infants by the practice of allowing them always to lie upon one side of the body. Here the deforming agent is simply the weight of the brain. Even in adults the skull is much less brittle than is commonly supposed, and notions derived from the study of dried specimens are apt to be erroneous. During life a sharp knife properly directed may be driven through the cranial vault so as to cause only a simple perforating wound with- out splintering, and without fracture of the bone beyond the puncture. Such a wound may be as cleanly cut as a wound through thick leather, and a specimen in the London Hospital museum serves well to illustrate this. A case reported in the Lancet for 1881 affords a strange instance of a knife penetrating the skull without apparently splinter- ing the bone. m A man wishing to commit suicide placed the point of a dagger against the skull in the upper frontal region, and then drove it well into the brain by a blow from a mallet. He ex- pected to fall dead, and was disappointed to find that no phenomena of interest developed. He then drove the dagger farther in by some dozen blows with the mallet, until the blade, which was four inches long, was brought to a standstill. The dagger was removed with great difficulty ; the patient never lost consciousness, and recovered without a symptom. 24 THE HEAD AND NEGK [CHAP. The following anatomical conditions tend to minimize the effects of violence as applied to tho skull : the density of the scalp and its great mobility ; the dome-like arrangement of the vault ; the number of the bones that compose the head, and the tendency of the violence to be broken up amongst the many segments ; the sutures which interrupt the continuity of any given force, and the sutural membrane, which acts as a kind of linear buffer ; the mobility of the head upon the spine ; and the elasticity of the cranial bones themselves. The skull is further strengthened by the pre- sence of six buttresses or pillars at the junction of the vault and base. Two of these are lateral, the orbito-sphenoid anteriorly and the petro-mastoid posteriorly, while the fronto-nasal and occipital strengthen the anterior and posterior ends of the skull. In children the membranous layer between the sutures is of considerable thickness, but as age advances this membrane disappears and the bones tend to fuse together (synostosis). The sutures begin to be obliterated about the age of 40, the change commencing on the inner aspect of the suture, and appearing first in the sagittal suture, then in the coronal and lambdoid, and last in the squamous. As age advances, moreover, the skull bones become thicker owing to a deposit over the inner table to replace the diminishing brain, and lose much of their elasticity. They are, there- fore, more readily fractured in the aged than in the young. As a rule, in fracture, the entire thickness of the bone is involved ; but the external table alone may be broken, and may even be alone depressed, being driven into the diploe, or, in the case of the lower frontal region, into the frontal sinus. The internal table may be broken without a corresponding frac- ture in the outer plate ; and in nearly all cases of complete fracture, especially in such as are at- tended with depression, the internal table shows more extensive splintering than does the external. n] jj -p FRACTURES OF THE SKULL 25 There are many reasons for this. The internal plate is not only thinner than the external, but is so much more brittle as to receive the name of the " vitreous table." A force applied to the external table may be extremely limited, and produce, as in a sabre cut, but a limited lesion. As the force, however, travels through the diploe it becomes broken up, and reaches the inner plate as a much more diffused form of violence. This is especially the case when parts of the outer table are driven in. Then, again, the internal plate is a part of a Fig. 8. smaller curve than is the external plate ; and, lastly, Agnew assigns a reason for the greater vul- nerability of the inner plate that has reference to the general yielding of the bone. In Fig. 7, AB represents a section of a part of the vault through both tables, and c D and E F two vertical and paral- lel lines. Now, if force be applied to the vault 26 THE HEAD AND NECK [CHAP. between these parallel lines, the ends of the arch, A B, will tend to become separated, and the whole arch, yielding, will tend to assume the curve shown in Fig. 8. In such case, the lines CD and EF will converge above and diverge below (Fig. 8), so that the violence would tend to force the bone particles together at the outer table and asunder at the inner table. Fractures of the vault are due to direct vio- lence. The construction of the skull is such that the fracturing force is resisted in many ways. (1) When a blow is received on the vertex in the parietal region, the force tends to drive the upper borders of the two parietal bones inwards. Such driving-in of these borders must be associated with a corresponding outward movement of the inferior borders. This latter movement is forcibly resisted by the squampus bone and the great wing of the sphenoid, which overlap the lower edge of the parietal bone. Moreover, the force transmitted to the squamous bone is passed on to the zygomatic arch, which takes its support from the superior maxillary and frontal bones. This arch then acts as a second resisting buttress, and this transmission of force from the vertex to the facial bones is said to be illustrated by the pain often felt in the face after blows upon the top of the head. (2) If the upper part of the frontal bone be struck, the force is at once transmitted to the parietal bones, be- cause the* upper part of the frontal bone (owing to the manner in which its border is bevelled) actu- ally rests upon the two parietal bones ; so the same resistance is again called into action. If there be any tendency for the inferior parts of the bone to move outwards, as would certainly be the case while the mid-frontal suture existed, such movement ^ would be resisted by the great wings of the sphenoid and by the anterior inferior angles of the parietal bones which embrace or overlap these parts of the frontal. Thus it will be seen that much depends upon the manner in which the corresponding edges of the frontal and parietal bones are bevelled. (3) n] FRACTURES OF BASE OF SKULL 27 Blows upon the occiput are less distinctly pro- vided for, and it must be owned that a by no means heavy fall is sufficient to break this bone. It must receive, however, much protection from its connexions with the two parietal and tem- poral bones, and from its articulation with the elastic vertebral column. Fractures of the base of the skull may be due to (1) direct or (2) indirect violence, or, most commonly of all, to (3) extension of a fracture from the vault. (1) The base has been fractured by direct violence due to foreign bodies thrust through the nasal roof, through the orbital roof, and through the base as it presents in the pharynx. The posterior fossa can also be fractured by vio- lence applied to the nape of the neck. (2) Of frac- tures by indirect violence the following examples may be given : Blows applied to the lower part of the frontal bone have been associated with no lesion other than a fracture of the cribriform plate or of the orbital part of the frontal, these parts being much disposed to fracture on account of their extreme tenuity. In 8G cases of fracture of the base of the skull, the orbital roof was involved in 79, the optic foramina in 63, and the cribriform plates in nearly all (Raw- ling). _ In falls upon the chin, the condyle of the lower jaw has been so violently driven against the glenoid cavity as to fracture the middle fossa of the skull. The force of a " knock-out " blow applied to the point of the chin produces concussion of the brain without fracture of the skull. When the body in falling has alighted upon the feet, knees, or but- tocks, the force has been transmitted along the vertebral column, and has led to fracture o.f the base in the occipital region. Such accidents are most apt to occur when the spine is kept rigid by muscular action, and the mechanism involved is precisely similar to that whereby the head of a broom is driven more firmly on to the^ brooms-handle by striking the extreme end of the stick against the ground. The theory that the base is often broken 28 THE HEAD AND NEOK [CHAP. by contre-coup is pretty generally abandoned, though there are a few cases that appear to support the suggestion. Such a case was recorded by Sir J. Hutchinson, and in it a fracture of the occipital bone was associated with a like lesion in the cribri- form plate, the intervening part of the skull being uninjured. (3) Fractures of the vault, and especi- ally linear fractures due to such diffused violence as obtains in a fall upon the head, are very apt to spread to the base. In so spreading they reach the base by the shortest possible route, and without any regard to the sutures encountered or to the density of the bones involved. Thus, fractures of the frontal region of the vault spread to the an- terior fossa of the base, those of the parietal region to the middle fossa, and those of the occipital region to the posterior fossa. To this rule there are but few exceptions. To indicate more precisely the exact bones involved in these three districts, P. Hewett has divided the skull into three zones. The anterior zone includes the frontal, the upper part of the ethmoid, and the f ronto-sphenoid ; the middle, the parietals, the squamous and anterior part of the petrous of the temporals, and the greater part of the basi-sphenoid ; and the pos- terior, the occipital, the mastoid, the posterior part of the petrous bone, with a small part of the body of the sphenoid. In all fractures of the base there is usually a discharge of blood and of cerebro-spinal fluid ex- ternally. (1) In fractures of the anterior fossa the blood usually escapes from the nose, and is derived from the meningeal and ethmoidal vessels, or in greater degree probably from the torn mucous lin- ing of the nasal roof. To allow of the escape of cerebro-spinal fluid from the nose, there must be, in^addition to the fracture in the nasal roof, a lacer- ation of the mucous membrane below that fracture, and of the sheaths of the olfactory nerves which are derived from the dura mater and arachnoid. A profuse discharge of cerebro-spinal fluid may take place through the nasal mucous membrane inde- n] SEPARATION OF SUTURES 29 pendently of inj ury. The discharge probably occurs along the sheaths of the olfactory nerves, and is caused by a lessened absorption or increased secretion of cerebro-spinal fluid. In many cases of fracture in the frontal region, blood finds its way into the orbit, and appears beneath the conjunctiva. (2) When the middle fossa is involved, the blood escapes from the external auditory meatus, through a rupture in the tympanic membrane, and is de- rived from the vessels of the tympanum and its membrane, or from an intracranial extravasation, and in some cases from a rupture of the cavernous or petrosal sinuses. The blood may follow the Eustachian tube, and may escape from the nose or mouth, or be swallowed and subsequently vomited. To allow of the escape of cerebro-spinal fluid by the ear ("the serous discharge "), (a) the fracture must have passed across the internal auditory meatus ; (6) the tubular prolongation of the membranes in that meatus must have been torn ; (c) there must be a communication between the internal ear and the tympanum ; and (d) the membrana tympani must have been lacerated. (3) In fractures of the posterior fossa an extravasation of blood may ap pear about the mastoid process or at the nape of the neck, or may even extend into the cervical region. It may be added that in compound fractures of the vault associated with tearing of the dura mater and arachnoid, an escape of cerebro-spinal fluid has in a few rare instances been noted. After simple fracture of the vault in children a swelling may form at the injured part which fluctuates, be- comes tenser when the patient cries, and may pos- sibly pulsate synchronously with the brain. Such swellings are due to a collection of cerebro-spinal fluid beneath the scalp, and indicate a coincident rupture of the brain membranes. Separation of* sutures. This condition, as the result of injury, is practically restricted to the young skull. In later life, force applied at the site of an obliterated suture may cause a frac- ture, which accurately follows the old suture line. 30 THE HEAD AND NECK [CUAP. Separation of the sutures, independent of fracture, is very rare in the adult skull. In the few instances of such a condition the temporal bone has usually been the one displaced and the separation noted at the squamous suture. When associated with fracture, the coronal and sagittal sutures are those most frequently separated, and the next in fre- quency is the lambdoid. The thickness of the skull-cap varies greatly, not only in different parts of the same skull, but also in corresponding parts in different individuals. The average thickness is 5 mm. (I of an inch). It varies with age: at birth the parietal is little more than 1 mm. ( 2 V of an inch) ; at three years diploe appear, marking off the inner from the outer table of the skull; in old people the parietal bone varies in thickness from 5-10 mm. (i-f of an inch). The thickest parts are at the occipital protuberance (where the section may measure 12 or 13 mm.), the mastoid process, and the lower part of the frontal bone. The bone over the inferior occipital f ossse and orbit is very thin, while it is thinnest over the squamous bone. Here the bone may be no thicker in parts than a visiting card, and appear as a translucent area in an X-ray photograph. The skull is also thinned over the sinuses and grooves for the meningeal vessels. It is especially thin over the anterior inferior angle of the parietal bone. It is important to remember in trephining that the inner table is not always parallel with the outer. Craniectomy. This operation is carried out in cases of microcephaly in infants and chil- dren. It consists in the removal of a strip of bone from the vertex of the skull so as to give to the brain, as an American author expresses it, " more elbow room." The operation presumes that the arrest of growth in the brain *is due to a retarded growth of the skull, but all the evidence at our dis- posal points to the arrest in the development of the brain as the primary lesion, the condition of the skull being a consequence. In hydrocephaly n] X-RAY EXAMINATION 31 the skull is seen to respond readily to the quick expansion of the brain ; if the growth of the brain is arrested, the skull remains small. X-ray exami nation of the temporal region. It is frequently necessary to examine the temporal region of the skull to discover the condi- tion of certain deep-seated intracranial structures. To find the position of such structures, certain easily-found surface-points must be marked by pellets of lead in order that they may serve as guides. The most convenient and reliable guide- points are those indicated in Fig. 9; they are A, the fronto-malar (fronto-zygomatic) notch; B, the malar angle; D, the premeatal pointy on the root of the zygoma, in front of the meatus, behind the mandibular (glenoid) fossa, and immediately above the postmandibular (postglenoid) spine; c, a point on the upper border of the zygoma, midway between B and D (midzygomatic point). These points should be marked on both sides of the skull, and the corresponding points of the two sides should be superimposed when the skull is examined in profile. When thus examined, the region covered by the two temporal muscles becomes an illuminated area owing to the thin- ness of the bones underlying the muscles. The illuminated area is subdivided into an anterior or frontal fenestra and a posterior or temporal fenestra (Fig. 9) by the fronto-temporal pillar of bone which carries the middle meningeal vessels and marks the separation of the frontal from the temporal lobes of the brain. At the point where trephining is usually performed for me- ningeal haemorrhage namely, 1-| inches behind and ^ an inch above the fronto-malar notch the shadow of the fronto-temporal pillar appears to divide into two an anterior horizontal branch which corresponds to the roof of the orbit and is situated ^ an inch above the fronto-malar notch, and a descending branch which reaches the upper b9rder of the zygoma just in front of c, the midzygomatic point. The descending 32 THE HEAD AND NECK [CHAP. branch represents the anterior wall of the middle cranial fossa, the spheno-orbital septum. It de- scends | of an inch behind the temporal border of the malar bone. It will thus be seen that between the spheno-orbital septum behind, the temporal border of the malar in front, the shadow of the TEMPORAL Ft IDG, ORBITAL FRONTO-MALAR SUTU, CORONAL. SUTURE FRONTAL. FENESTRA, FRONTO-TEMPORAL PILLAR OPTIC FORAMEN TEMPORAL FENESTRA 3OUAM . SUTURE PETROUS SHADOW MASTO - PARIETAL I ., PILLAR I LATERAL S//VJ/3 THMOIDAL SINUS INT. AUD.MEAT. STOfD PfOC. EXT. At/0. MEAT., POST. OLN. SPINE ARTIC. TUBERCLE SPHZNOIDAL SINVS SPHENO-ORBITAL WALL Fig. 9. Structures seen in the temporal region when the skull is examined in profile by means of X-rays. orbital roof above, and the upper border of the zygoma below, there is marked out a very dis- tinct retromalar area in which lie the middle and posterior ethmoidal cells. The area is crossed from behind forwards, and below the level of the fronto-malar notch, by two lines, the lower of which corresponds to the level of the cribri- form plate, and the upper to the junction between n] X-RAY EXAMINATION 33 the lateral mass of the ethmoid and the orbital plate of the frontal bone. At the lower limit of the retromalar area lie the spheno-maxillary (pterygopalatine) fossa, the spheno-maxillary fis- sure, the spheno-palatine ganglion, and the com- mencement of the infraorbital nerve. Along the lower border of the temporal fenestra appear structures of the utmost consequence. Enumerating these from before backwards, we note: the lesser wing of the sphenoid, the pituitary fossa (fossa hypophyseos), crowned anteriorly by the anterior clinoid process, and posteriorly by the dorsum sellse and posterior clinoid processes. Behind the dorsum sellse lies the black triangular shadow of the petrous bone, ending posteriorly in the masto-parietal pillar. The floor of the pituitary fossa lies \ an inch (12 mm.) above the upper border of the zygoma, its anterior limit lying directly above the midzygo- matic point. The antero-posterior diameter of the pituitary fossa is normally about 12 mm. (^ an inch) in adults. The optic foramen lies 1^ inches (37 mm.) behind the fronto-malar notch, and 1 inch (25 mm.) above the upper border of the zygoma. The premeatal point (see Fig. 9) marks the hinder aspect of the basilar process; the internal auditory meatus lies | an inch behind and above this point; the external auditory meatus is situated immediately behind and below it, while the basion, at the anterior margin of the foramen magnum, lies | an inch below and behind this point. The sphenoidal sinus lies below and in front of the pituitary fossa. CHAPTER III THE CRANIAL CONTENTS Membranes of the IM.SIII. The dura mater, from its toughness, forms an excellent protec- tion to the brain. It is very intimately adherent to the bone over the whole of the base of the skull, and consequently in this situation extrava- sations between the membrane and the bone are scarcely possible. Over the vault its attachments are comparatively loose, but it is very closely adherent along the lines of the sutures. This lax attachment allows large hsemorrhagic and puru- lent extravasations to collect between the dura mater and the bone. Such extravasations usually lead to compression of the brain, and it may be noted that in the great majority of all cases of compression the compressing force is outside the dura mater. Thus, in uncomplicated cases when symptoms of compression come on at the time of an accident, the cause is probably depressed bone; when they appear after a short interval, the cause is probably extra vasated blood between the mem- brane and the bone; and when a long interval (days or weeks) has elapsed after the accident, the cause is probably a collection of pus in the same situation. Sir C. Bell pointed out that the dura mater of the vault may be separated from the bone by the vibration produced by a blow. "Strike the skull of a subject with a heavy mallet; on dissecting you find the dura mater to be shaken from the skull at the point struck. Repeat the experiment on an- other subject, and inject the head minutely with size injection, and you will find a clot of injection 34 MIDDLE MENINGEAL ARTERY 35 lying betwixt the skull and dura mater at the part struck, and having an exact resemblance to the coagulum found after violent blows on the head." Tillaux has demonstrated that the adhesions be- tween the dura mater and the bone are particularly weak in the temporal fossae, the most .usual site of meningeal haemorrhage. When blood is poured out between the dura mater and the bone in cases of fracture, the vessels which give way are the middle me- niiigeal much more frequently the companion veins than the .artery. The veins form a sinus round the artery (Wood- Jones). The artery, having passed through the foramen spinosum, divides into two branches : the anterior, the larger, runs upwards across the anterior inferior- angle of the parietal bone and ascends the vault a short distance behind the coronal suture; the posterior runs backwards, with a horizontal sweep across the squamous bone, and takes the course of the second temporal convolution. (See Figs. 3, 4, pp. 13, 15.) The vessels are very frequently torn as they cross the anterior angle o FISSURE O Fig. 15. The convolutionary projections of the pre- central gyms, and their relationship to motor areas. (Symington and Crymblc.) ing on the surface of the brain first excites the cortex to action; hence one situated over a motor area excites the movements represented in that area, or one over a sensory area excites the sensations represented there. Stimulation of the cortex is soon followed by its destruction and loss of function; hence loss of movement or loss of sensation replaces the preliminary in] THE BRAIN 51 excitement. The symptoms produced by intra- cranial growths are apt not to be definitely localized, because even a small tumour may pro- duce widely distributed compression effects when it is situated within the rigid walls of the skull. Conjugate movements of the eyes are represented in the cortex at the posterior end of the mid- frontal convolution (Fig. 14). There are also several primary sensory areas of cortex areas connected with sight, hearing, and smell which may be affected by intracranial lesions, and give signs which assist the surgeon ^ to localize the seat of disease. The visual cortex is situated near the calcarine fissure and round the occipital pole; the "word-seeing" centre occupies the angular gyrus (Fig. 12) ; the auditory cortex lies in a deep or buried part of the superior temporal convolu- tion, while the " word-hearing " centre is ascribed to the middle third of this convolution. The ol- factory cortex is placed in the uncus, which is situated to the inner side of the temporal lobe. Tumours in the neighbourhood of the uncus, besides producing disturbance of the olfactory sensations, frequently give rise to "dreamy states." Of the brain generally little has to be said. In a surgical sense, it presents itself simply as a large mass of soft tissue that may be damaged by shaking, as gelatin may be when shaken in a case. As it is of very yielding structure, and does not entirely fill the cranial cavity, it may, as it were, be thrown about within the skull, and be damaged by collision with its walls. In contusion or bruis- ing of the brain it is noticed that the lesion is very much more frequently situate on the under surface, both as regards the cerebrum and cere- bellum, than in any other part (see p. 39). To this statement, however, there is the striking exception that those parts of the base of the cerebrum that rest upon the large basal collection of the cerebro-spinal fluid are the least often con- tused. These parts include the medulla, the pons, an-d the interpeduncular space. 52 THE HEAD AND NECK (CHAP Blood supply. The brain is very lavishly sup- plied with blood-vessels. The main arterial trunks (vertebral and internal carotid) both become tortu- ous before entering the skull, in order, probably, to diminish the effects of the heart's systole upon the brain. On entering they are almost immedi- ately blended into an anastomosing circle (circle of Willis), which has the effect of equalizing the cerebral circulation. It is only when one of the main arteries entering into the formation of the circle of Willis becomes blocked that the communicating channels are of service. If a coloured solution be injected into the left carotid of a living dog, the colouring is confined to the left hemisphere ; but if the right carotid be pre- viously tied, then the colouring matter is found in the right as well as the left half of the brain (Kramer). Embolism of the middle cere- bral artery leads to a widespread destruction of the cerebral cortex. It supplies the third frontal, the upper and middle temporal, the angular, supramarginal, and the lower two- thirds of the ascending frontal and parietal gvri. The only parts of the sensori-motor areas which escape de- struction in such a case are those for the lower limbs and trunk. The anterior cerebral artery supplies these centres, the mesial surface of the frontal and parietal lobes, and the adjacent part of the cortex on the outer aspect. The occipital lobe and temporo-sphenoidal convolutions are supplied by the posterior cerebral artery. Liga- ture of one common carotid may produce no effect upon the brain, although the mortality after this operation is mainly due to cerebral complica- tions. One carotid and the two vertebrals would appear to be able to bring enough blood to the brain, but some weeks will elapse before the communicating vessels are sufficiently enlarged to give a uniform distribution of blood to all parts of the brain. Both common carotids have been ligatured, or one carotid has been secured when its fellow of the opposite side has been in] CEREBRAL BLOOD SUPPLY 53 occluded by disease, and no marked cerebral disturbances have followed. In no case, how ever, has the patient recovered when the interval between the closing of the two vessels was less than a few weeks. The vertebral arteries can carry a sufficient amount of blood to the brain if only the strain be thrown upon them gradu- ally, and the brain be allowed to accommodate itself slowly to the change. After ligaturing all four arteries in the dog, the anastomosis between the spinal and cerebral arteries within the fora- men magnum was sufficient to maintain life (Hill). Plugging of any of the smaller cerebral arteries by emboli, as a rule, leads at once to a disastrous result. Such embolism is met with in surgery in connexion with aneurysm of the common carotid. In simply examining such aneurysms, a little piece of the clot contained in the sac has been detached, has been carried up into the brain, and has produced a plugging of one of the cerebral vessels. Thus, hemiplegia has followed upon the mere examination of a carotid aneurysm, as in a case recorded by Mr. Teale, of Leeds. Fergusson's treatment of aneurysm at the root of the neck, that of displacing the clots by manipulation, has been abandoned on this same score. In the second case treated by manipula- tion by this surgeon, one of subclavian aneurysm, paralysis of the left side of the body followed at once upon the first handling of the tumour. The pulsations of the brain may be communi- cated to any tumours or collections of fluid that reach the surface of the brain through an aper- ture in the skull. Such pulsations are synchron- ous with the arterial pulse, but the sphygmo- graphic tracings of the cerebral pulsations exhibit also the "respiratory curve," conveyed directly from the thorax by the blood within the veins. The valve at the lower end of the jugular vein prevents direct regurgitation of blood from the heart to the brain, but it does not prevent the transmission of pressure. 54 THE HEAD AND NECK Although wounds of the brain bleed freely, the bleeding is checked without difficulty, the vessels being capable of ready contraction. Large tumours have been excised from the cortex of the brain, without undue trouble from haemor- rhage. The terminal branches of the cerebral arteries anastomose freely in the pia mater, but the minute arteries which perforate and supply the cortex are terminal. Hence any pressure applied to the surface of the brain will lead to anaemia of that piece of cortex, and, if the pressure is continued, to its destruction. Ligature of a cerebral vein usually leads to an atrophy of the cortex which it drains (Horsley). There is always one sometimes more anastomos- ing vein on the surface of the cerebrum, uniting the upper with the lower cerebral veins. The lower cerebral veins are four in number : three of them leave the temporal and occipital lobes to end in the lateral sinus; the other, the superficial Sylvian vein, ends in the sinus of the small wing of the sphenoid. The temporal and occipital lobes cannot be lifted off the tentorium without rup- turing the veins joining the lateral sinus. Nearly all the veins of the cerebellum end in the lateral sinus; its arteries are derived from the vertebral and basilar. The various arteries supplying the cerebellum, pons, and medulla are terminal in their ^ distribution, each nerve-centre and area having its own vascular supply (Stop- ford). Tumours in the cerebellum give rise to muscular weakness and inco-ordination, giddi- ness, and loss of balance. The vermis, or middle part of the cerebellum, is more directly connected with bending movements of the trunk, while the lateral lobes are concerned in the co-ordination of turning movements movements made round the vertical axis of the trunk (Horsley). The evidence is steadily increasing which makes us regard the cortex of the cerebellum as demar- cated into functional and regional areas. CHAPTER IV THE ORBIT AND EYE THE ORBIT THE antero-posterior diameter of ^the orbit is about If inches (44 mm.), its vertical diameter at the base a little over 1| inches (31 mm.), and its horizontal diameter at the base about H inches (37 mm.). The diameters of the globe are : transverse, 24 mm. ; antero-posterior, 24-5 mm. ; vertical, 23 mm. (Brailey). The eye- ball is therefore nearer to the upper and lower margins of the orbit than to the sides, and the greatest interval between the globe and the orbital wall is on the outer side. The interior of the orbit is most conveniently reached by incisions made to the outer side of the globe, and, in excision of the eyeball, the scissors are usually introduced on that side when the optic nerve has to be divided. In excis- ing the left eye, however, it may be more con- venient to divide the optic nerve from the inner side. The bones forming the floor, the roof, and the inner wall of the orbital cavity are very thin, especially in the last-named situation. Thus, foreign bodies thrust into the orbit have readily penetrated into the cranial cavity, into the nose and ethmoidal cells, and, when directed from above, into the antrum (see Fig. 26, p. 107). In several instances a sharp-pointed instrument, such as the end of a stick or foil, has been thrust into the brain through the orbit, and has left but little external evidence of this serious lesion. 55 56 THE HEAD AND NECK [OWAI>. Nelatori mentions a case in which the internal carotid artery was wounded through the orbit. A reference to the relations of the orbital walls will show that a tumour may readily invade the orbit by spreading (1) from the base of the skull, (2) from the nasal fossae, (3) from the maxillary sinus, and (4) from the temporal or infratemporal (zygomatic) fossae. In any of these instances the growth may enter the orbit by destroying the intervening thin layers of bone, and in tumours of the maxillary sinus this is the usual mode of entry. It may, however, extend more readily from the cranial cavity through the optic foramen or superior orbital (sphenoidal) fissure, from the nose through the naso-lacrimal duct, and from the two fossae named through the inferior orbital (spheno-maxillary) fissure. After violent blows upon the temple, . blood has found its way into the orbit through the inferior orbital fissure, and has led to subconj unctival ecchymosis. Dis- tension of the frontal sinus by retained mucus or pus may lead to a prominent tumour at the upper and inner margin of the orbit, above the level .of the internal (medial) palpebral ligament, which may cause displacement of the globe down- wards, outwards, and forwards. The bones of the orbit are peculiarly apt to be the seat of ivory exostoses, which may in time entirely occupy the orbital cavity. The anterior third of the outer wall of the orbit is separated from the temporal fossa by the malar (os zygomaticum) (Fig. 16) ; the posterior two-thirds are separated by the great wing of the sphenoid from the middle fossa of the skull, which contains the temporal lobe. Kronlein re- moves intraorbital tumours by opening the outer wall of the orbit in the temporal fossa. In a notorious case, in which a murderer attempted to commit suicide, the bullet entered the temporal fossa, perforated the outer wall of the orbit, and destroyed the eyeball, but left the brain un- touched. The pole of the temporal lobe is situ- IVJ CAPSULE OF TENON 57 ated from 2 to 2'5 cm. behind the outer margin of the orbit (see Fig. 4, p. 15, and Fig. 9, p. 32). Fascia bulbi (capsule of Tenon). The best description of this structure has been given by Lockwood, of whose researches Prof. Cunningham provides the following resume: " The capsule is a firm loose membrane spread over the posterior five-sixths of the globe, the cornea alone being free UT.TARSAL Liq. CAPSULE TEMPORAL FOSSA EXT. CECTUS Fig. 16. Showing the arrangement of the capsule of Tenon (fascia bulbi) and check ligaments. The eyeball is turned outwards so that the external check ligament is taut and the internal relaxed. from it. In front it lies under the ocular conjunctiva, with which it is intimately connected, and it ends by blending with, that membrane close to the margin of the cornea [Fig. 16]. Behind, it fuses with the sheath of the optic nerve, where the latter pierces the sclerotic. The surface of the membrane towards the globe is smooth, and is connected to the eyeball by some soft yielding areolar tissue. It thus forms a kind of dome for the globe, a species of socket or bursa in which it 58 THE HEAD AND NECK [CHAP. moves. The posterior surface of the capsule is in contact with the orbital fat. The tendons of the ocular muscles pierce thfe capsule opposite the equator of the globe [Fig. 16]. The lips of the openings through which the four recti pass are prolonged backwards upon the muscles, in the form of sheaths, very much as the internal spermatic fascia is pro- longed upon the cord from the internal abdominal ring." Where the internal and external recti per- forate, strong expansions of the capsule spread out to the inner and outer walls of ^the orbit. Because these expansions limit the action of the two recti they are known as the check ligaments (Fig. 16). They allow a side-to-side movement of the . cornea to the extent of about 45. The external check ligament is the stronger, and is attached to the outer wall immediately behind the external palpebral raphe (tarsal ligament) ; the attachment of the internal ligament is close behind the lacrimal sac. A prolongation of the capsule passes to the trochlea round the tendon of the superior oblique. The suspensory ligament of the eyeball stretches across the orbit like a hammock, supporting the eyeball. It is really a thickening of the under part of the fascia bulbi, its attachment to the orbital walls being made by means of the internal and external check ligaments. When the upper jaw is removed the surgeon should take care to preserve the attach- ments of the suspensory ligament. If these be destroyed the eyeball will sink downwards. The intimate relation of the fascia bulbi to the eyeball, conjunctiva, orbital muscles, and orbital walls has to be kept in mind where opera- tions are undertaken to remedy squint. From Fig. 16 it will be seen that, after the tendon of a rectus muscle is cut through as it lies within the cansnle of Tenon, the mnscle still possesses, through the continuity of its sheath with the cap- sule, an attachment to the eyeball and conjunc- tiva as well as to the orbital wall by the check ligament. Hence, when the tendon of a muscle is completely cut it can still act on the eyeball ; its ivj FOREIGN BODIES IN THE ORBIT 59 complete retraction is prevented by the check ligament. The orbit behind the fascia bulbi is occupied by a large quantity of loose fat, in addition to the ocular muscles, vessels, and nerves. It is by the absorption of this fat that the sunken eye is produced in cases of emaciation and prolonged illness. This tissue affords a ready means for the spread of orbital abscess. Such an abscess may follow injuries, certain ocular inflammations, periostitis, etc., or may spread from adjacent parts. The pus may occupy the entire cavity, dis- placing the eyeball forwards, limiting its move- ments, and causing, by interference with the cir- culation, great redness of the conjunctiva and swelling of the lids. Foreign bodies, some of them of remarkable size and shape, have lodged for long periods of time in the orbital fat without causing much trouble. Thus, Lawson reports a case where a piece of an iron hat-peg, 3 inches long, was em- bedded in the orbit for several days without the patient being aware of it. A stranger case, in some ways, is that reported by Furneaux Jordan : " A man who was employed in threshing became the subject of severe ophthalmia. At the expira- tion of several weeks, the patient, whilst pressing his finger on the lower eyelid, suddenly ejected from a comfortable bed of warm pus a grain of wheat, which had shot forth a vigorous green sprout." The orbital fat affords also an excellent nidus for growing tumours. Fractures of the inner wall of the orbit involving the nasal fossae or sinuses may lead to extensive emphysema of the orbital cellular tissue. The air so introduced may cause the globe to protrude, may limit its movements, may spread to the lids, and will, in any case, be increased in amount by blowing the nose, etc. Orbital muscles. The four recti muscles end in thin, flat membranous tendons. The ten- don of the external or internal rectus muscle is 60 THE HEAD AND NECK [CHAP. frequently divided for strabismus. The width of the tendons varies from 7 mm. to 9 mm. They are inserted into the sclerotic near the cornea. The internal rectus is inserted 6'5 mm. from the corneal margin, the external 6*8 mm., the inferior 7'2 mm., and the superior 8 mm. (Merkel). While the internal and external recti are pure internal and external rotators of the eyeball, the superior and inferior recti, owing to the line in which they pull, act as internal as well as up- ward and downward rotators. Their tendency to act as internal rotators is counterbalanced by the two oblique muscles, which serve as external as well as upward and downward rotators. INF. OBLIQ. R. SUP. SUP. OBLIQ. SUP. OBLIQ. Fig. 17. Diagram to show the action of the orbital muscles. The arrows show the direction of the action of each muscle. The diagram given in Fig. 17 will help to make the actions of the orbital muscles clearer. Conjugate horizontal movements to the right or left are executed by the internal and external rectus muscles. When the cornea is turned upwards the muscles in action are the inferior oblique and superior rectus, the first-named tend- ing to turn the cornea towards the temporal as- pect, the second towards the nasal aspect. The two muscles involved in turning the cornea down- wards are the inferior rectus and superior oblique, the first deflecting the movements towards the nasal side, the second towards the malar side. The diagram also serves to show the muscles of iv] ORBITAL ARTERIES AND NERVES 61 the right and left sides, which are co-ordinated in conjugate movements. Thus, in turning the eyes downwards and to the right, the superior oblique of the right side acts with the inferior rectus of the left. If one of these muscles is paralysed, then double-vision or diplopia occurs when this movement is carried out. Further, it must be remembered that in all of these move- ments the muscle which is positively in action is controlled by its opponent, which is negatively in action. If the opponent should become para- lysed, the active muscle pulls on the eyeball until it is opposed by the check ligament. In life, all the orbital muscles are in a state of tonus and exert a pressure on the eyeball. The orbital arteries are small, and seldom give rise to trouble when divided in excising the globe, since they can be readily compressed against the bony walls of the cavity. Pulsating tumours of this part may be due to traumatic aneurysms of one of the orbital arteries, or may depend upon an arterio-venous aneurysm formed between the internal carotid artery and the cavernous sinus. Pressure upon the ophthalmic vein (as it enters the sinus) by an aneurysm of the internal carotid vessel may also produce ^ all the symptoms associated with pulsating orbital tumours. Thrombosis of the cavernous sinus causes dilatation of the ophthalmic veins and proptosis. The orbital nerves may be damaged in wounds of the orbit, or in fractures of the orbit and of the base of the skull; they may be pressed upon by tumours from various parts, by aneu- rysms, hsemorrhagic and inflammatory effusions. Thus, Lawson records a case in which the optic nerve was divided by a stab through the upper eyelid, without the globe being injured, and with- out any bone being fractured. The same nerve has also been completely torn across in fractures of the orbit, and has been pressed upon in frac- tures involving the lesser wing of the sphenoid. 62 THE HEAD AND NECK [CHAP. The third, fourth, and sixth nerves, and the tirst division of the fifth, may be affected in cases of aneurysm involving the internal carotid artery, where they lie in relation with the cavernous sinus. They may readily be pressed upon, also, by any growth involving the inferior orbital fissure, such as a periosteal node springing from the mar- gin of the fissure, while the sixth nerve, from its more intimate connexion with the base of the skull, has been directly torn across in a fracture involving that part (Prescott Hewett). In paralysis of the third nerve there is droop- ing of the upper lid (ptosis) ; the eye is almost motionless, presents a divergent squint from unopposed action of the external rectus muscle, and cannot be moved either inwards, upwards, or directly downwards. Rotation, in a direc- tion downwards and outwards, can still be effected by the superior oblique and outer rectus muscles. The pupil is dilated and fixed; the power of accommodation is much impaired, there is diplopia, and sometimes a little protrusion of the globe from relaxation of the recti muscles. These symptoms refer to complete paralysis of the nerve. In cases of partial paralysis, only one or two of the above symptoms may be present. In paralysis of the fourth nerve there is often but little change to be seen, since the func- tion of the superior oblique muscle, supplied by this nerve, may, in part, be performed vicari- ously. " There is usually only very slight defect in the mobility of the eye; what there is occurs chiefly^ in the inner and lower angle of the field of vision ; there is deviation of the eye inwards and upwards on lowering the object, and simply upwards when it is turned far towards the healthy side " (Erb). In any case there will be diplopia, especially in certain positions of the globe. In paralysis of the sixth nerve there is con- vergent strabismus, with consequent diplopia, and an inability to rotate the eye directly out- wards. Paralysis of the sixth nerve may be iv] PARALYSIS OF ORBITAL NERVES 63 accompanied by paralysis of the nerve to. the internal rectus of the opposite side, giving rise to conjugate deviation of the eyes. Such a condi- tion indicates a lesion in the nucleus of the sixth nerve, for, although the fibres for the internal rectus pass out with the third nerve, they take their origin with the sixth. Sometimes all the oculo-motor nerves of the eye are paralysed, and in such cases the lesion is probably situated either at their nuclei of origin or at the cavernous sinus, in the wall of which the nerves lie close together. In paralysis of the first division of the fifth there is a loss of sensation in all the conjunctiva, except such as covers the lower lid (supplied by the palpebral branch of the infraorbital nerve), loss of sensation in the globe, and in skin sup- plied by the supratrochlear and supraorbital nerves, and in the mucous and cutaneous surfaces supplied by the nasal (naso-ciliary) nerve. The area of anaesthesia is much less than the ana- tomical distribution of the nerve, owing to the extent to which cutaneous nerves overlap. No reflex movements (winking) follow upon irri- tation of the conjunctiva, although the patient can be made to wink on exposing the eye to a strong light, the optic nerve in this case transmitting the impression to the nucleus of the facial nerve. Neither can sneezing be ex- cited by irritating the mucous membrane in the anterior part of the nose. Destructive ulceration of the cornea may follow this paralysis, due partly ^to damage to the trophic branches con- tained in the paralysed nerve, partly to the anaes- thesia which renders the part readily injured, and partly to the loss of the reflex effect of the sensory nerves, upon the calibre of the blood-vessels, wherebv the inflammation is permitted to go un- controlled (Nettleship). In paralysis of the cervical sympathetic there is narrowing of the palpebral fissure from some drooping of the upper lid, apparent recession 64 THE HEAD AND NECK [CHAP of the globe within the orbit, and some narrow- ing of the pupil from paralysis of the dilator muscle of the iris, which muscle is supplied by the sympathetic. The drooping of the upper lid may be explained by the fact that each eyelid contains a layer of unstriated muscle fibre. That in the upper lid arises from the under surface of the levator palpebrse, and is attached to the tarsal cartilage near its upper margin (Fig. 20, p. 81). This layer of muscle, which, when in action, would keep up the lid, is under the influence of the cervical sympathetic. The recession of the globe is supposed by some to be due to paralysis of the orbitalis muscle. This muscle bridges over the inferior orbital fissure, is composed of unstriated fibres, and is innervated by the sympathetic. Contraction of the muscle (as pro- duced by stimulation of the cervical sympathetic in animals) causes protrusion of the globe, while section of the sympathetic in the neck produces retraction of the eyeball (Claude Bernard). No changes are observed in the calibre of the blood- vessels of the globe. The non-striated muscle maintains the intraorbital pressure, and thus assists in the return of blood from the ophthalmic veins. In animals such as the ox, in which the veins of the orbit become dilated when the head is carried low, as in browsing, this musculature attains a great development. THE EYEBALL The cornea. The thickness of the cornea varies from 0'9 mm. in the central parts to 1-1 mm. at the periphery. One is apt to be a little deceived as to its thickness, and on intro- ducing a knife into the cornea, the instrument, if not entered at the proper angle, may be thrust for some little distance among the laminae of the part. In front the cornea is covered by stratified epithelium. When^ this layer has been removed by abrasion, a white deposit of lead salts may take place in the exposed cornea! tissue in cases IV] THE EYEBALL 65 where lead lotions are used. The bulk of the cornea is made up of a great number of fibrous lamellae, between which are anastomosing cell spaces containing the corneal corpuscles. If the nozzle of a fine syringe be thrust into the corneal tissue, the network of lymph-spaces can be filled with injection. When suppuration takes plaice within the proper corneal tissue, it is probably INA CHOP, CANAL OF SCH ' f~OVEA CEHTRALIS OPTIC DISC FtlJ-RATION ANCLE OPTIC NERVE. HYALOID CAKAL Fig. 18. Horizontal section of the eyeball, showing the suspensory ligament of the lens, the aqueous and vitreous chambers, entrance of the optic nerve,and the fovea centralis. (After Schaffer.} along these canals, modified by inflammation, that the pus spreads, thus producing onyx. The cornea contains no trace of blood-vessels, except at its extreme periphery, where the capillaries of the sclerotic and conjunctiva end in loops. When inflamed, the tissue always becomes opaque. In the affection known as interstitial keratitis, blood-vessels from the arteries of the margin of t> 60 THE HEAD AND NECK [CHAP. the cornea penetrate into the substance of the cornea for some distance. As liiese vessels are some little way below the surface, and are covered by the hazy ccrneal tissue that is the result of the disease, their scarlet colour is much toned down, and a strand of such vessels is called a "salmon patch." In the condition known as pannus, the cornea appears to be vascularized ; but here, owing to continued irritation, vessels, derived from the neighbouring conjunctiva! arteries, pass over the cornea just beneath its epithelial covering, leaving the cornea proper as bloodless as ever. The term arcus senilis is ap- plied to two narrow white crescents that appear at the periphery of the cornea, just within its margin, in the aged, and in certain morbid con- ditions. They are due to fatty degeneration of the corneal tissue, and the change is most marked in the layers of the cornea just beneath the anterior elastic lamina, i.e. in the part most influenced, by the marginal blood-vessels. In spite of its lack of a direct blood supply, wounds of the cornea heal kindly. The cornea is very lavishly supplied with nerves, estimated to number from forty to forty-five. They are derived from the ciliary nerves, enter the cornea through the fore part of the sclerotic, and are distributed to every part of the tunic. These nerves are not sensitive to touch, heat, or cold, only to painful stimuli. In glaucoma, a disease of which the phenomena depend upon greatly increased intraocular pres- sure, the cornea becomes anaesthetic. This depends upon the pressure to which the ciliary nerves are exposed before their branches reach the cornea. (See also Nerve Supply of the Eyeball, p. 71.) Sclera, clioroicl, ami iris. The sclera or sclerotic is thickest behind, and thinnest about \ of an inch from the cornea. When the globe is ruptured by violence it is the sclerotic that most commonly yields, the rent being usually a iv] SOLERA AND CHOROID 67 little way from the cornea, i.e. in or about the thinnest part of the tunic. The sclerotic may be ruptured while the lax conjunctiva over it remains untorn. In such a case the lens may escape through the rent in the sclera, and be found under the conjunctiva. At the point of penetration of the optic nerve the sclera is thin, and pierced by numerous holes for the pas- sage of nerve bundles. This weakened portion, the lamina cribrosa, plays an important part in glaucoma (p. 78). It gives the stippled appear- ance to the optic papilla. Brailey states that the lateral parts of the sclera are thinner than the upper and lower segments, the inferior part being the thickest and the external wall the thin- nest. It happens, therefore, that under the influ- ence of intraocular pressure the eye expands more laterally than in the vertical direction. It is mainly to the denseness and unyielding character of the sclerotic that must be ascribed the severe pain (due to pressure on nerves) experienced in those eye affections associated with increased intra- ocular tension (glaucoma, etc.). The choroid is the vascular tunic of the globe, and carries its main blood-vessels. Between the choroid and sclera are two thin membranes, the lamina suprachoroidea and lamina fusca, which are separated from one another by a lymph space. In injuries to the globe, therefore, ex- tensive bleeding may take place between these two coats, and indeed a like haemorrhage may ^be the result simply of a sudden diminution in the ocular tension produced by such an operation as iridectomy or cataract extraction. The choroid alone has been ruptured (usually at its posterior part) as the result of a blow upon the front of the eye. The choroid is one of the few parts of the body that may be the seat of melanotic growths. These growths are sarcomatous tumours containing a large amount of pigment, and occur only where pigment cells are found. In the choroid coat pigment cells arc very abundant. 68 THE HEAD AND NECK [CHAP. The iris is very vascular, and liable to be the site of inflammation (iritis). From its relations to the cornea and sclera it happens that inflammation in those tunics can spread without difficulty to the iris. On the other hand, the vessels of the iris and choroid are so intimately related that inflamma- tions set up in the iris itself have every induce- ment to spread to the choroidal tunic. When the iris is inflamed its colour becomes altered, owing to the congestion of the part and to the effusion of lymph and serum that takes place in its substance. The swelling to which it becomes subject, together with the effusion, produce a blurring of its delicate reticulated structure, as seen through the cornea. Owing also to the swollen condition of the little membrane, the pupil becomes encroached on, and appears to be contracted, while the move- ments of the membrane are necessarily rendered very sluggish. If it be remembered that part of the posterior surface of the iris is in actual contact with the lens capsule, it will be understood that inflammatory adhesions may readily take place between the two parts (Fig. 18). After iritis, therefore, it is common to find the posterior sur- face of the iris (most often its pupillary margin) adherent to the lens capsule by bands of lymph, either entirely or in one or more different points. Such adhesions constitute posterior synechise, the term anterior synechise being applied to adhesions between the iris and the cornea. In iritis also the lens may become involved, and the condition of secondary or inflammatory cataract be produced. The iris is not very closely attached at its insertion (Fig. 19). Thus, .in the case of injury to the eye, it may be torn more or less from its attachments without any damage being done to the other tunics. The iris has been com- pletely torn away in a few instances, and has escaped through a wound of the globe. The ciliary processes have been thus exposed. Congenital absence of the iris has been recorded. In cases of penetrating wounds of the cornea the iris may iv] THE IRIS 69 easily become prolapsed. It is so delicate and yield- ing a membrane that in performing iridectomy the necessary piece of the iris can be seized and pulled out through the corneal incision without offering sensible resistance. The membrane also derives much support from its contact with the lens, for in cases where the lens has been displaced into the vitreous, or has been removed by operation, the iris is observed to be tremulous when the globe is moved. Although very vascular, the iris seldom bleeds much when cut, a circumstance that is prob- ably due to the contraction of the muscular fibres that exist so plentifully within it. Sometimes the iris presents in its substance a congenital gap that runs from the pupil downwards and a little in- wards. This condition is known as coloboma iridis, and is due ' to the persistence of the " choroidal cleft" formed during development of the optic cup. In other cases there can be seen, stretch- ing across the pupil, some shreds of the pupillary membrane. This membrane, which is apparent for a few days after birth in some animals, is entirely absorbed long before birth in the human species. It will now be convenient to take note of the blood and nerve supply of the globe. Blood supply of the eyeball. 1. The short ciliary arteries (from the ophthalmic) pierce the sclera close to the optic nerve, run some little way in the outer coat of the choroid, and then break up into a capillary plexus that makes up the main part of the inner choroidal coat. In front this plexus gives some vessels to the ciliary processes. The veins from these vessels are disposed in curves as they converge to four or five main trunks (vense vorticosse), which pierce the sclera midway be- tween the cornea and the optic nerve. In the choroid they lie externally to the arteries. 2. The two long ciliary arteries (from the ophthalmic) pierce the sclera to the outer side of the op^tic nerve and run forwards, one on either side, until they reach the ciliary region, where they 70 THE HEAD AND NECK [CHAP. break up into branches that, by anastomosing, form a vascular circle about the periphery of the iris (the circulus major). From this circle some branches pass to the ciliary muscle, while the rest run in the iris in a converging manner towards the pupil, and at the margin of the pupil form a second circle (the circulus minor). 3. The anterior ciliary arteries (from the mus- cular and lacrimal branches of the ophthalmic) pierce the sclerotic (perforating branches) about 2 to 3 mm. behind the cornea, join the circulus major, and give off branches to the ciliary pro- cesses, where they form copious anastomosing loops. These arteries lie in the subconjunctival tissue. Their episcleral or non-perforating branches are very small and numerous, and are invisible in the normal state of the eye. In inflammation of the iris and adjacent parts, however, these ves- sels appear as a narrow pink zone of fine vessels round the margin of the cornea, that run nearly parallel to one another, are very closely set, and do not move with the conjunctiva. This zone is known as the zone of ciliary congestion, or the circumcorneal zone. 4. The vessels of the conjunctiva are derived from the lacrimal and the two palpebral arteries. These vessels, in cases of inflammation, are readily distinguished from those last described. They are of comparatively large size, are tortuous, are of a bright brick-red colour, can be easily moved with the conjunctiva, and as easily emptied of their blood by pressure. The differences presented by these^two sets of vessels serve in one way to dis- tinguish inflammation of the conjunctiva from that involving deeper parts. The conjunctival vessels around the margin of the cornea form a closer plexus of anastomosing capillary loops, which be- come congested in severe superficial inflammation of the cornea, and may then form a zone around the margin of the cornea, which can, however, be distinguished from the "ciliary zone" by the general characters just named. iv] VESSELS OF THE EYEBALL 71 The retina has a vascular system of its own, supplied through the arteria centralis retinae, which is nowhere in direct communication with the choroidal vessels, except just at the entrance of the optic nerve. Indeed, the outer layers of the retina which are in relation with the choroid coat are entirely destitute of vessels. Thus, when the central artery of the retina becomes plugged, sudden blindness follows, and, as the meagre collateral circulation that is established by the minute anastomoses about the entrance of the nerve is quite insufficient, the retina soon becomes oedematous. A permanent plugging of the central artery means, therefore, a practical extinction of the vascular system of the retina. In some cases of embolism, only a branch of the retinal artery is plugged, the patient retaining vision except in that part of the retina supplied by the branch. The fovea centralis, the centre of acute vision, receives twigs from both the superior and inferior temporal branches of the arteria centralis retinae. In cases of haemorrhage between the choroid and retina the blood must come from the choroidal vessels ; and in haemorrhage into the vitreous, which often follows injury, the blood may be de- rived from the retinal vessels, since they run in the inner layers of that membrane, or from the vessels in the ciliary region. Nerve supply of tlie eyeball. l. The cili- ary nerves, derived from the ciliary (lenticular) ganglion and the nasal (naso-ciliary) nerve, pierce the sclerotic close to the optic nerve, and pass forwards between the sclerotic and the choroid, supplying those parts. They enter the ciliary muscle, form a plexus about the periphery of the iris, and then send fibres into the iris, which form a fine plexus as far as the pupil. They send branches through the fore part of the sclerotic to the cornea. Thus the eyeball obtains through these nerves its sensory fibres from the nasal or naso-ciliary branch of the first division of the 72 THE HEAD AND NECK [CHAP. fifth, its motor fibres for the ciliary muscle and sphincter iridis from the third nerve, and many sympathetic fibres, among which are those that supply the dilator muscle of the iris (see p. 64). 2. The conjunctiva is supplied by four nerves : above, the supratrochlear; inner side, the infra- trochlear; outer side, the lacrimal (all branches of the first division of the fifth) ; below, the palpe- bral branches of the second division of the fifth. As the ciliary nerves pass forwards between the choroid and the sclerotic, it will be seen that they are readily exposed to injurious pressure against the unyielding sclerotic in cases of increased intra- ocular tension. The sensation of the globe itself is derived solely from the first division of the fifth. In inflammatory affections of the globe, as in corneitis or iritis, be- sides the pain actually felt in the eye, there is pain referred along other branches of the first division of the fifth. The explanation of this fact has to be sought for in the common origin of the ophthalmic division from the upper sensory nucleus of the fifth nerve in the floor of the fourth ventricle. Not only are the nerve cells connected with the eyeball disturbed, but the neighbouring cells also are affected, and by a psychical error the pain is reflected along the nerves with which these neighbouring cells are connected. There is pain over the forehead along the supratrochlear, the supraorbital, and the lacrimal branches (cir- cumorbital pain), and pain down the side of the nose following the nasal nerve. Or the pain may spread to the second division of the fifth, and discomfort be felt in the temporal region (orbital branch of the second division), or be referred to the upper jaw and teeth. These affections, too, are associated with much lacrimation, the lacri- mal gland being also supplied through the first division of the fifth. Photophobia, or intoler- ance of light, is common in inflammatory affec- tions of the eye. In this condition there is spasm pf the orbicular muscle, keeping the eye closed, iv] NERVES OF THE EYEBALL 73 or closing it on the least exposure to irritation. Although the orbicular muscle is supplied by the facial nerve, its nerve fibres are derived, not from the nucleus of the seventh but from the oculo- motor nucleus, situated near the upper sensory nucleus of the fifth, and connected with it by reflex paths. Photophobia is most marked in superficial affections of the cornea, and is often much benefited by a seton in the temporal region. Inflammation of the iris and glaucoma are accom- panied by hypersesthesia and referred pains over the outer frontal and anterior temporal areas (Head). The nerve-centres for the skin of this region and the eyeball are closely connected, a relationship which may explain the application of counter-irritation to the temples in eye disease. Inflammation of the cornea gives rise to no referred pains (Head). Strain of the ciliary muscle, which occurs with errors of refraction, is one of the commonest causes of headache, leading to referred pains and areas of hypersesthesia over the midorbital region of the forehead. The relations between the nasal (naso-ciliary) nerve and the orbital contents receive many illustrations in practice. Thus, if the front of the nose be struck, or the skin over its lower part be irritated, as by squeezing a painful boil, profuse lacrimatiori will frequently be produced. Snuff, too, by stimulating the nasal branch of the ophthalmic nerve, often makes the eyes of the uninitiated to water ; and it is well known that there are many disturbances about the nose, and the anterior part of the nasal fossae, that can "make the eyes water." Herpes zoster often provides a remarkable illus- tration of the intimate relation between the nasal nerve and the eye. In this affection, when the regions of the supraorbital and supratrochlear branches of the first division are alone implicated, the eye is usually unaffected; but when the erup tion extends over the part supplied by the nasal nerve, i.e. runs down the side of the nose, then 74 THE HEAD AND NECK [CHAP. there is very commonly some inflammation of the eyeball. Dangerous area of the eye. Penetrating wounds of the cornea alone, or of the sclera alone, behind the ciliary region, are by no means serious ; but wounds involving the ciliary body, or its immediate vicinity, are apt to assume^ the gravest characters. Inflammation in the ciliary region is peculiarly dangerous, on account of the important vascular and nerve anastomoses that take place in the part. Indeed, as regards blood and nerve supply, there is no more important district in the eyeball. From the ciliary body also inflammations can spread, more or less directly, to the cornea, iris, chproid, vitreous, and retina. Plastic, or purulent, inflammation of the ciliary body, after injury, is the usual starting- point 'of sympathetic ophthalmia. ^ In this terrible affection destructive inflammation is set up in the opposite sound eye, which is, however, not usually involved until two or three months after the other eye has been injured. It is now generally believed that the sound eye is directly infected from the diseased one. The subarachnpid spaces which sur- round the optic nerves are- in continuity at the chiasma, and offer a path whereby infection may spread from one eye to the other. The lens measures of an inch from side to side, and of an inch from before backwards. All through life it slowly increases in size. It, together with its capsule, is in all parts per- fectly transparent and perfectly non-vascular. The manner in which the lens is maintained in position is shown in Figs. 18 (p. 65) and 19 (p. 77). The circumference of the lens is fixed to the ciliary processes by a system of fine, transparent, radial fibres (the suspensory liga- ment of the lens), some of which pass in front of the lens, while others pass behind it, thus forming a sac or capsule for the lens. On the ciliary processes the radial fibres of the sus- pensory ligament become continuous with the iv] LENS AND RETINA 75 transparent capsule of the vitreous humour the hyaloid membrane. The lens may easily be loosened or displaced by partial rupture of its suspensory ligament, and may find its way into the anterior chamber, or, more commonly, back into the vitreous. If disturbed, the lens may swell, and by the pressure thus exercised cause great damage to the important structures adjacent to it. The capsule is very brittle and elastic, and when torn its edges curl outwards. It is lacerated in the usual operations for cataract, and may be ruptured by many forms of violence applied to the eyeball. " In one form of cataract operation the capsule is removed with the lens, the vitreous being retained in position by the hyaloid membrane which lies behind the capsule of the lens" (Lieut. -Colonel H. Smith). When the capsule is wounded the aqueous humour enters, and is imbibed by the lens fibres, which in conse- quence swell up and become opaque, thus produc- ing a traumatic cataract. In the various forms of cataract the whole lens, or, more commonly, some portion of it, becomes the seat of opacity. This often commences in the nucleus, and for a long while remains limited to that part; or it may first involve the cortex, and in such a case the opacity takes the form of a series of streaks that point towards the axis of the lens,' and are dependent upon the arrangement of the lens fibres. Of the retina it is only necessary^ to observe that its connexion with the choroid is so slight that it may easily be detached from that mem- brane by hsemorrhagic or other effusions, and may indeed be so detached by a simple blow upon the globe. Even when extensively detached it remains, however, #s a rule, attached at both the optic disc and the or a serrata. The length of the optic nerve within the orbit is 28-30 mm. As it passes from the brain it receives its perineural sheath from the pia mater, and, in addition, two other sheaths : an 76 THE HEAD AND NECK [CHAP. outer from the dura mater, and an inner from the arachnoid. These sheaths remain distinct and separate, and the two spaces enclosed may be in- jected, the outer from the subdural, the inner from the subarachnoid space. Thus inflammatory affec- tions of the cerebral meninges can readily extend along the optic nerve to the optic disc through these spaces in the nerve sheath, while in cases of intracranial disease other than meningeal the mischief may extend from the brain to the disc along the interstitial connective tissue in the n^rve. These connexions may serve in part to explain the frequent association of optic neuritis with intra- cranial disease. As the^nerve leaves the skull in the optic foramen it is in contact with the outer wall of the sphenoidal sinus, or, if that sinus be relatively small, with the posterior ethmoidal cells. In suppuration of these spaces infection may spread to the optic nerve, and thus set up optic neuritis. When the intracranial pressure is raised by the growth of a tumour, haemor- rhage, or other condition within the skull, that pressure is exerted on the optic nerve, thus interfering with a free circulation along the nerve, and leading to a change in the appearance of the optic disc. Aqueous and vitreous humours. The aqueous fills the anterior chamber, the space between the capsule and suspensory ligament of the lens and the cornea. The iris divides this space into two parts, the anterior and posterior. Since, however, the iris is largely in actual contact with the lens, is happens that the posterior part is repre- sented by a little angular interval between the iris, the ciliary processes, and the suspensory ligament of the lens (Fig. 19). The depth of the anterior chamber is 3'6 mm. The innej stratum of the cornea, as it becomes continuous with the sclera, splits up into fibres which pass to (1) the sclera, (2) the ciliary muscle, (3) the cili- ary processes. The fibres form the ligament um pectinatum, and the intervals between its fibres IV] AQUEOUS HUMOUR 77 are known as the spaces of Fontana (iridio-corneal spaces). They are filled by the aqueous humour. The fluid in these spaces is absorbed into a circular canal in the sclera the circular venous canal, or canal of Schlemm (see Fig. 19). This canal is in communication with the veins of the anterior part of the sclerotic, ciliary processes, and iris. The aqueous humour is being con- stantly secreted by the ciliary processes behind CONJUNCTIVA CANAL OF SCHLEMM PECTINATE LIQ. CILIARY Muse. LENS Fig. 19. Ligamentum pectinatum, spaces of Fontana, ciliary muscle, and capsule of the lens. the iris, and equally constantly absorbed into the canal of Schlemm, thence passing into the venous circulation. The tension of the eyeball is maintained by an exact regulation between the rates of secretion and absorption. Thus, if pus finds its way into the anterior chamber (hypopyon) it is, as a rule, easily absorbed. The same applies to moderate extravasations of blood in the chamber, and the speedy removal of such effusions contrasts with the difficulty that is 78 THE HEAD AND NEGK [CHAP. experienced in the absorption of blood from the vitreous chamber. Prof. Arthur Thomson has shown that the inner aspect of the sclera is depressed or grooved at the anterior base of the iris. When the pupil is dilated the contracted base of the iris tends to fill this groove, thus rendering the escape of the aqueous humour into the spaces of Fontana more difficult. The vitreous takes little active share in ocular maladies. It may be secondarily affected in in- flammation of adjacent parts, may be the seat of haemorrhages, and is often occupied by opaque bodies of various kinds. Foreign bodies have lodged in the vitreous for considerable periods without causing any symptoms. The muscse volitantes that so often trouble the myopic are due to little opaque particles in the vitreous, and very often have exactly the appearance that the corpuscles of the vitreous present when seen under the microscope. The delicate transparent membrane which en capsules the vitreous humour is known as the hyaloid membrane. The vitreous is readily separ- ated from the retina, except behind, opposite the disc where the artery to the lens enters in the foetus and passes forwards, in the hyaloid canal, to supply the fcetal pupillary membrane. This vessel is a branch of the central artery of the retina, and may persist as a fibrous cord in adult life. In some rare cases it has continued to transmit blood, and in such instances its pulsation can be seen with the ophthalmoscope. Olaucoma is a disease the symptoms of which are all dependent upon an increase in the intra- ocular tension of the globe. When the pressure within the eyeball rises above the pressure of the blood in the arterioles of the retina and choroid, then the nutrition of the eye ceases. Normally the intraocular tension is equal to that of the blood in the intraocular veins. If there is a failure in absorption of the aqueous humour into the circular iv] GLAUCOMA 79 venous canal of the sclera, then pressure rises. The condition is the same as in the brain ; the aqueous humour of the eye represents the cerebro-spinal fluid of the brain. It is remarkable that in nearly every case of glaucoma the spaces of Fontana are occluded by the complete obliteration of the angle between the periphery of the iris and the cornea, which angle is normally occupied by the ligamen- tum pectinatum. The importance of the peripheral part of the anterior chamber in relation to the outflow of fluid from the eye is shown in many ways. If this part be blocked by the iris in perforation of the cornea, or by the lens in some disloca- tions of that body, increased tension of the globe is apt to follow. The relief given to glaucoma by iridectomy appears to depend upon the circum- stance that the operation practically opens up again these channels of communication from the aqueous, since the procedure, to be successful, should involve an incision so far back on the sclera as fully to pass through the angle just alluded to. It is needful also that the iris should be re- moved quite up to its attachment, and that the portion resected should be considerable. Iridec- tomy also exposes a fresh capillary surface of the iris to the aqueous humour, which thus finds a fresh exit. In the young the ligamentum pectinatum is cellular and open in structure ; it becomes fibrous and contracted in the old. Hence the aged are more liable to glaucoma (T. Henderson). The symptoms of glaucoma are all explained by the effects of the abnormal tension. Thus, the ciliary nerves are compressed against the unyield- ing sclera, and give rise to intense pain, while the disturbance in their functions shows itself in the fixed and dilated pupil and in the anaes- thetic cornea. Perhaps the first parts to suffer from compression are the retinal blood-vessels, and the effect upon them will be most obvious at the periphery of the retina, i.e. at the extreme 80 THE HEAD AND NECK [CHAP. limit of the retinal circulation. Hence follows that gradual narrowing of the visual field which is constant in glaucoma, while the pressure upon the optic nerve produces those flashes of light and other spectra which occur in the disease. The weakest part of the sclera is in the disc at the lamina cribrosa. This part rapidly yields under the pressure, and so produces the "glauco- matous cup." Pressure in the opposite direction pushes the lens forwards, and thus narrows the anterior chamber; while the general interference with the ocular circulation is shown in the dis- tended vessels that appear upon the globe. The eyelids (Fig. 20). The skin over the eye- lids is very thin and delicate, and shows readily through its substance any extravasation of blood that may form beneath it. Its laxity, moreover, renders it very well adapted for certain plastic operations that are performed upon the part. Its loose attachments cause it to be readily influenced by traction, and the shrinking of cicatrices below the lower lid is very apt to draw that fold away from the globe, and so produce the condition of eversion of the lid known as ectropion. The con- traction of the conjunctiva after inflammatory con- ditions, or after it has been subjected to destructive agencies, is prone, on the other hand, to curl either lid inwards towards the globe, and thus to produce fntropion. The lids present many transverse folds ; one of these on the upper lid, deeper and more marked than the rest, divides the lid into two parts, the part below being that which covers the globe, the part above being that in relation with the soft structures of the orbit. In emacia- tion the lid becomes much sunken in the line of this fold. Incisions should follow the direction of the fold. The lids are very freely supplied with blood, and are often the seat of nsevi and other vascular growths. The following layers are found in either lid in order: (1) the skin; (2) the subcutaneous tissue; (3) the orbicularis oculi ; (4) the tarsal plate IV] THE EYELIDS 81 (superior tarsus) and its continuation to the margin of the orbit the orbital septum (palpebral mem- brane) ; (5) the layer of tarsal (Meibomian) glands embedded in the plate; and (6) the conjunctiva. In the upper lid the levator palpebrse is found passing to the tarsal plate. The subcuta- neous tissue is very lax, and hence the lids swell greatly when cedematous, or when inflamed, and when the seat of haemor- rhage. On this ac- count it is inadvisable to apply leeches to the lids, because of the extensive "black eye" that may follow. This tissue is peculiar in containing no fat. At the 'edge of the lids are found the eye- lashes, the orifices of the tarsal glands, and of some modified sweat- and sebaceous glands. The secretion of these glands pre- vents adhesion of the edges of the lid. This edge, like other points of junction of skin and mucous mem- Fig. 20. Vertical section through upper eyelid. (After Waldeyer.) a, Skin ; &, orbicularis ; b', its ciliary part ; c, involuntary muscle of eyelid representing part of the insertion of the levator palpe- brse ; d, conjunctiva ; e, superior tarsus; /, tarsal gland; g, modi- fled sweat-gland ; h, eyelashes : i, post-tarsal glands. brane, is apt to be the seat of irritative affections. As it is a free border also the circu- lation is terminal, and stagnation in the blood 82 THE HEAD AND NECK [CHAP. current is not difficult to produce. Sycosis, an inflammation involving the hair-follicles and some of the glands at the edge of the lid, is among the most common of ophthalmic affections. The common stye also is a suppuration in the con- nective tissue or in one of the glands at the margin. On everting the lid the tarsal glands can be seen through the conjunctiva as lines of yellowish granules. The common tarsal cyst is a retention cyst developed in one of these glands. Two arteries supply either lid : a palpebral branch of the ophthalmic running along the inner part, and a branch of the lacrimal along the outer part of each lid. Four nerves supply the upper eyelid, the supraorbital, the supratrochlear and infratrochlear, and the lacrimal. One nerve supplies the lower lid, the infraorbital. Some of the lymphatics of the eyelids enter the pre- auricular glands, hence in cases of chancre of the lid the glandular enlargement has nearly always been noticed in front of the parotid gland. The conjunctiva. The ocular part of this membrane is thin, covered with stratified epithe- lium very loosely attached, and not very exten- sively supplied with blood; the palpebral portion is thicker, covered with columnar epithelium more closely adherent, and more vascular. At the edge of the cornea the conjunctiva becomes continuous with the epithelium covering that tunic. The loose- ness of the ocular conjunctiva allows it to be freely moved about, and is of great value in some opera- tions, as, for example, in Teale's operation for symblepharon, where a bridge of conjunctiva, dis- sected up from the globe above the cornea, is drawn down over the cornea to coyer a raw surface in con- tact with the lower lid. This lax tissue favours the development of oedema (chemosis), which in ex- treme cases may reach such a degree that the patient cannot close his eye. The vessels also, being feebly supported, are prone to give way under no great provocation. Thus, subconjunc- tival haemorrhages may occur from severe vomit- iv] THE CONJUNCTIVA 83 ing, or during a paroxysm of whooping-cough. Blood also may find its way beneath the membrane in fractures of the base of the skull. Haemorrhages beneath the membrane are unlike other extravasa- tions (bruises), in that they retain their scarlet colour. This is. due to the fact that the thinness of the conjunctiva allows oxygen to reach the blood and gives it an arterial character. Severe inflammation of the conjunctiva may lead to con- siderable cicatricial changes, as is the case in other mucous membranes, and especially, perhaps, in the urethra. The contraction of the conjunctiva after destructive processes is apt to lead to en- tropion. If both the ocular and the corresponding part of the palpebral conjunctiva have been de- stroyed, the two raw surfaces left will readily ad- here ; the lid will become fused to the globe, and the condition called symblepharon be produced. This condition concerns the lower lid, and is gener- ally brought about by lime or other caustics being accidentally introduced between the under lid and the globe. In one common form of inflammation of this membrane a number of little " granulations " ap- pear upon the palpebral conjunctiva. These are not real granulations, since no true ulceration of the part takes place, but they appear to be made up, some of nodules of adenoid tissue, others^ of gnlarged mucous follicles and of hypertrophied papillae, all of which structures are normally found in the membrane. The condition is known as "granular lids," and is associated with the form- ation of much new tissue in the deeper parts of the membrane. From the absorption of this new tissue and of these granulations a contracting cicatrix results, leading to much puckering of the membrane, and often to entropion and inversion of the eyelashes. liacrimal apparatus. The lacrimal gland, which is situated in the upper and outer quadrant of the orbit (Fig. 21), is separated by the lateral expansion of the tendon of the levator palpebrae 84 THE HEAD AND NECK [CHAP. into two parts a large superior, lying between the expansion and the roof of the orbit, and a small inferior, which lies between the expansion and the reflection of the conjunctiva from the eyeball to the upper eyelid. The ducts, minute in size and about twelve in number, open in the outer part of the conjunctival reflection. Excision of the gland presents no technical difficulty, as it is loosely bound to the structures in its neighbour- hood. It may inflame, and become so enlarged as to appear as a tumour, which may displace the globe downwards and inwards, and press forwards the oculo-palpebral fold of conjunctiva. If an abscess forms, it most usually breaks through the skin of the upper Hd. Cystis of the gland (dacryops) are due to obstruction and distension of some of its ducts. The normal secretion of the gland keeps the exposed surface of the eye moist, yet the gland may be excised without giving rise to any untoward effect. The lacrimal sac is situated at the side of the nose, near the inner canthus (medial palpebral commissure), and lies in a groove on the lacrimal and superior maxillary bones (Fig. 21). On its outer side, and a little anteriorly, it receives the two lacrimal canaliculi. In front of the sac is the internal palpebral ligament or tendo oculi. If the two lids be forcibly drawn out- wards this ligament can be readily felt and seen, and serves as a guide to the sac. It can also be felt as it is tightened when the lids are firmly closed. It crosses the sac at right angles, and at about the junction of its upper third with its lower two-thirds. A knife entered immediately below the ligament would about open the middle of the sac; and it may be noted that a lacrimal abscess, when about to discharge, always points below the ligament. Epiphora, or overflow of tears, is due in the main to two causes: (1) to an obstruction in any part of the lacrimal pas- sages, from the puncta to the opening of the nasal or naso-lacrimal duct in the nose; (2) to any cause IV] THE LACRIMAL SAC 85 that removes the lower punctum from its contact with the globe, as may be the case in ectropion, in entropion, in swelling of the lower lid, etc. It is the pretarsal part the fibres of the orbi- cularis oculi which span the lids near their free margin that keeps the eyelids appressed to the eyeball. These fibres end behind the lacrimal sac on the posterior lacrimal crest, and form the muscle LAC. GLAND Pl-ICA SEMILUN. CANALICULUS NASION Fig. 21. Diagram of the lacrimal apparatus. The arrow points to the first molar tooth, showing the direction of the nasal duct. at one time known as the tensor tarsi or Homer's muscle (Whitnall). Facial palsy causes epiphora, because, the orbicular muscle being relaxed, the punctum falls away from the globe, and. more- over, the passage of the tears is no longer aided by the suction action effected by the muscle in the process of winking. The canaliculi may readily be slit up with a proper knife, and a probe can without difficulty be passed down the nasal duct from the lacrimal sac. 86 THE HEAD AND NECK The nasal duct (naso-lacrimal) is a little over an inch in length, and the probe that traverses it should pass downwards, and a little backwards and outwards, in the direction of the first molar tooth (Fig. 21). The nasal duct per- forates the mucous membrane of the nose below the inferior turbinate process very obliquely, so that its inner wall acts as a valve. If this is destroyed by ulceration, as sometimes occurs in syphilis, the lacrimal sac may be inflated by blowing the nose. The bony nasal duct has a calibre which varies from 2'5 to 7'5 mm. in dia- meter ; the thick mucous membrane which lines it has a rich venous plexus in its submucous layer which readily swells and prevents the passage of tears when the duct is inflamed. The normal duct will take a probe measuring 3'5 mm. in diameter ; it must be remembered that the lumen of the duct is normally closed, and that its lining membrane possesses several transverse folds which may catch the point of a probe. Inflammatory conditions readily ascend from the nasal cavity to the lacri- mal sac through the nasal duct. As affections of the lacrimal sac are often very painful, it may be noted that the nerve supply of the sac is derived from the infratrochlear branch of the nasal nerve. CHAPTER V THE EAR The pi 1111:1. The pinna may be congenital ly absent, or there may be accessory auricles situated upon the cheek or side of the neck. In the latter situation the so-called accessory or supernumerary auricle consists of an irregular leaf of fibro- cartilage developed from the margins of one of the lower branchial clefts (see p. 209). The tag- like supernumerary auricles that are found on the cheek just in front of the pinna or meatus are due to the irregular development or want of fusion of one or more of the six tubercles from which the pinna itself is developed. The pinna may present a congenital fistula dependent on a defective closure of the first branchial cleft. The position of this cleft is represented in the normal ear by the Eustachian tube, the tympanum, and the external auditory meatus, the pinna being developed from the integument bordering the cleft. Some of the smaller and more superficial fistulse are due not to a defective closure of the branchial cleft but to want of complete fusion between certain of the tubercles from which the pinna is primarily developed. Accidental removal of the pinna is usually associated with but comparatively little diminution in the acuteness of hearing. The skin covering the auricle is thin and closely adherent. The subcutaneous tissue is scanty, and contains but very little fat. In inflammatory con- ditions of the surface, such as erysipelas, the pinna may become extremely swollen and very great pain be produced from the tenseness of the parts. The pinna and cartilaginous meatus are 87 88 THE HEAD AND NECK [CHAP. very firmly attached to the skull, so that the body, if not of great weight, may be lifted from the ground by the ears; but the experiment is cruel and dangerous. The external auditory meatiis is about 1| inches long. It is important to remember that the meatus is directed forwards as well as inwards ; to reach and expose the middle ear the surgeon takes the posterior wall of the meatus as a guide. The external meatus, the promontory, the cochlea, and the internal meatus lie nearly in the same line. The canal has a vertical curve about its middle, with the convexity upwards. To straighten the canal for the introduction of specula and other in- struments, the pinna should be drawn upwards and a little outwards and backwards. The osseous part forms a little more than one-half of the tube, and is narrower than the cartilaginous part. In the infant at 1 year, a third only of the meatus is formed of bone; the rest is car- tilaginous. In a child 5 or 6 years of age the bony and cartilaginous portions of the meatus are about of the same length (Symington). The narrowest portion of the meatus _ is about its middle. The outer orifice is elliptical, with its greatest diameter directed from above downwards ; therefore specula should be elliptical in shape rather than round. The inner end of the tube, on the other hand, is slightly wider in the transverse direction. Owing to the obliquity of the mem- brana tympani, the floor of the meatus is longer than the roof. The cartilaginous segment of the tube presents many sebaceous glands that may be the seat of minute and very painful abscesses. ^ It also presents numerous ceruminous glands, which secrete the cerumen of the ear, and which, when their secretion is excessive, may produce the plugs of wax that often block the meatus and cause deaf- ness. In the cartilage of the floor of the meatus are certain fissures, fissures of Santorini. They are filled up with fibrous tissue. They permit of easier movement of the cartilaginous meatus. It is v] EXTERNAL AUDITORY MEATUS 89 through these gaps in the cartilage that a parotid abscess may burst into the meatus. There are neither hairs nor glands in the lining of the bony part of the tube. The skin of the meatus, when inflamed, may pro- duce an extensive muco-purulent discharge, otitis externa. Polypi are apt to grow from the soft parts of the canal, and exostoses from its bony wall. Foreign bodies are frequently lodged in the meatus, and are often very difficult to extract. It would appear that in many cases more damage is done by the surgeon than by the intruding substance. Mason reports three cases where a piece of slate-pencil, a cherry-stone, and a piece of cedar-wood were lodged in the canal for respectively 40, 60, and 30 years. The upper wall of the meatus is in relation with the cranial cavity, from which it is only separated by a dense layer of bone. Thus, abscess or bone dis- ease in this part may possibly lead to meningitis. A case is reported where an inflammation of the cerebral membrane followed upon the retention of a bean within the meatus. The anterior wall of the canal is in relation with the temporo- maxillary joint and with part of the parotid gland. This may serve in one way to explain the pain often felt in moving the jaw when the meatus is inflamed, although, at the same time, it must be remembered that movement of the lower maxilla produces a movement in the cartilagin- ous meatus, and that both the canal and the joint are supplied by the same nerve (the auriculo- temporal). From its relation to the condyle of the jaw, it follows that this wall of the meatus may be fractured in falls upon the chin. Tillaux states that abscess in the parotid gland may spread into the meatus through the anterior wall of the passage. The posterior wall separates the meatus from the mastoid cells. Directly behind the posterior wall, at a distance of 12 or 15 mm., is the lateral sinus (Fig. 24). The inferior wall of the bony meatus is very dense and sub- 90 THE HEAD AND NECK [CHAT. stantial, and corresponds to the vaginal and styloid processes. Blooct supply. The pinna and external meatus are well supplied with blood by the tem- poral and posterior auricular arteries, the meatus receiving also a branch from the internal maxillary. In spite of this supply, the pinna is frequently the seat of gangrene from frost-bite. This^ is due to the fact that all the vessels are superficial and lie close beneath the surface, that the part is much exposed to cold, and that the pinna lacks the pro- tection of a covering of fat. The same conditions predispose to gangrene of the nose from external cold. Bloody tumours (hsematomata) are often met with on the pinna, and are common in boxers, football players, and lunatics. They are due to injury, and consist of an extravasation between the perichondrium and the cartilage. TVerye supply. The pinna is supplied by the auriculo-temporal, great auricular, and small occipital nerves (see Fig. 2, p. 11). The meatus is supplied mainly by the auriculo-temporal, with, in addition, a contribution from the auri- cular branch of the vagus (Arnold's nerve), which goes to the lower and back part of the canal, not far from its commencement. A sen- sory branch from the facial also ends in the meatus (Ramsay Hunt). The auricular branch of the vagus has been credited with a good deal in connexion with the nerve relations of the ear. After a heavy dinner, when the rose-water comes round, it is common to see the more experienced of the diners touch the lower part of the back of the ear with the moistened serviette. This is said to be very refreshing, and is supposed to be an unconscious stimulation of Arnold's nerve, a nerve whose main trunk goes to the stomach. Hence, this little branch has been facetiously termed "the alderman's nerve." Ear coughing:, ear sneezing, ear yawning. It is not uncommon to have a troublesome dry cough associated with some mischief in ihe v] THE EAR 91 meatus. Sometimes the mere introduction of a speculum will make the patient cough. A case is reported in which a troublesome cough persisted for eighteen months, and at once ceased on the re- moval of a plug of wax from the ear. In such cases the irritation is conveyed to the respiratory and cough centres in the floor of the fourth ventricle by the auricular branch of the vagus. Gaskell has shown that the vagus also contains the dis- associated visceral fibres of the fifth nerve. Hence, disturbances may be set up in the vagal nuclei through branches of the fifth nerve, such as the auriculo-temporal. The connexion of the nerves of the external auditory meatus with the vagal nuclei explains, too, the sneezing or vomiting which is sometimes caused by the presence of foreign bodies in the external meatus. The same nerve- connexion also explains the occurrence of repeated yawning, sometimes set up by ear ailments. Irrita- tion conveyed along the inferior dental or lingual nerves may be referred along the auriculo-tem- poral. Hence the need to examine the tongue and lower teeth in cases of earache. Head has pointed out that disease of the ear, the tonsil, ^the tongue, or the lower jaw may be associated with an area of tenderness in the skin along and below the jaw. It is a common practice to introduce ear-rings with the idea of relieving obstinate affections of the ^ eye. The lobule is supplied by the great auricular nerve which springs from the second and third cervical nerves, while the eye is supplied by the ophthalmic division of the fifth. The centres with which these nerves are connected have a defi- nite connexion, for the lower sensory nucleus of the fifth is a direct continuation upwards of the grey matter from which the posterior roots of the cervical nerves arise. Hilton reports a case of obscure pain in the ear which was found to be due to an enlarged gland in the neck that pressed upon the trunk of the great auricular nerve. M < mlr:i 11:1 ly m JKIIU. This membrane is very 92 THE HEAD AND NEGK [CHAP. placed, forming with the horizontal an angle of 45. At birth it appears to be more nearly horizontal, although it is not really so. Owing to the sloping downwards of the bony wall of the meatus at its inner end, that wall forms with the lower edge of the membrane a kind of sinus in Fig. 22. Section through the external meatus, middle ear, and Eustachian tube. (Tillaux.} a, External auditory meatus ; b, attic of tympanum ; c, Eust tube ; d, internal auditory meatus ; e, cochlea ;/, ossicles ; (/, brana tympani : h, styloid process. Eustachian mem- which small foreign bodies may readily lodge (Fig. 22). The ring of bone to which the membrane is attached is deficient at its upper and anterior part. The gap so formed is called the tympanic notch or notch of Rivini, and is occupied by loose connective tissue, covered by a continuation of the v] MEMBRANA TYMPANI 93 lining of the meatus, and through it pus may escape from the middle ear into the auditory canal without perforating the membrane. When the membrane gives way owing to a violent concussion transmitted through the air, it often gives way opposite the notch, its attachments here being ob- viously less secure than elsewhere. The membrane possesses but little elasticity, as shown by the very slight gaping of the part after it has been wounded. It is for this reason, among others, that perfora- tions made in the membrane by the surgeon heal so very rapidly. The membrane has been ruptured during fits of sneezing, coughing, vomiting, etc. The same lesion has followed a box on the ear, and even simple concussions such as that produced by a loud report. The umbo, or deepest point of the depression, is just below the centre of the entire membrane, and corresponds to the attachment of the end of the handle of the malleus. The rest of the handle can be seen through the membrane dur- ing life. The head of the malleus is in no con- nexion with the membrane, being situated in the attic of the tympanum above the level of the mem- brane (Fig. 22). The segment of the membrane above the umbo is very freely supplied by vessels and nerves ; it corresponds to the handle of the malleus, and to the chain of ossicles, and is opposite to the promontory and the two fenestrse. The chorda tympani nerve also runs across this supraumbilical portion. The segment below the umbo, on the other hand, corresponds to no very important parts, and is less vascular and less sen- sitive. Paracentesis of the tympanum through the membrana tympani should therefore always be performed in the subumbilical segment. If per- formed above the umbo the knife may strike the incus and loosen that bone from its attachments, or the chorda tympani may be cut, which would give rise to a paralytic secretion of saliva. The malleus and stapes are too firmly attached to be readily detached. 94 THE HEAD AND NECK [CHAP. The membrane is supplied by the stylo-mastoid artery and the tympanic branch of the internal maxillary, and obtains its nerve supply from the auriculo-temporal, facial, and vagus. The tympanum. The width of the tympanic cavity, as measured from its inner to its outer wall, varies from 2 to 4 mm., T V to | of an inch. The narrowest part is that between the umbo of the membrana and the promontory. A fine rod A/NTCUM ,EXT.5EMICIRC.CA/HAL ADITUS FENESTRA OVALIS TECMEM TVMPANI PROCES5U5 COCM. Fig. 23. Inner wall of tympanum and antrum. The position of the external semicircular canal and course of the facial nerve (vii.) are shown. thrust through the centre of the membrana tympani would hit the promontory of the inner wall of the cavity. Above the promontory is the fencstra pvalis (fenestra vestibuli), and below and behind it the fenestra rotunda (fenestra cochleae) (Fig. 23). Skirting the upper and posterior margin of the inner wall of the tympanum is the facial canal or aqueduct of Fallopius, containing the facial nerve. The wall of the aqueduct is so thin that inflammatory mischief can readily extend from the middle ear to the facial nerve. The upper v] TYMPANIC SINUS 95 wall or roof is very thin, and but little bone separates it from the cranial cavity. The suture between the squamous and petrous bones is found in this wall, and by means of the sutural mem- brane which separates the bones in the young, inflammatory changes may readily spread from the tympanum to the meninges. The petro-squamous suture unites at the end of the first year and usually contains the petro-squamous vein, a remnant of the primitive jugular. The floor is very narrow. Its lowest part is below the level of both the mem- brana tympani and the orifice of the Eustachian tube, and hence pus may readily collect in this locality (Fig. 23). It is separated by a thin piece of bone from the internal jugular vein behind, and from the internal carotid artery in front. Fatal haemorrhage from the latter vessel has occurred in connexion with destructive changes in this part of the ear. The posterior wall in its upper part presents the opening or aditus of the tympanic sinus (antrum of the mastoid). This air sinus opens into the attic that part of the tympanic cavity which is situated above the level of the membrana tympani (Fig. 24). The tympanic sinus (aiitrum of* the mas- toid) (Figs. 22 and 24) lies above and behind the external auditory meatus. Implication of this space and of the mastoidal cells, which open into it and surround it, forms one of the most serious complications of middle-ear disease. It is large enough to contain a small bean, and is present at birth (Fig. 25), being developed with the cavity of the tympanum. It is closely surrounded by important structures. Its roof, formed by the tegmen tympani, a plate of bone only 2 mm. thick, separates it from the third temporal convolution. Small veins perforate the roof to join the petro-squamous vein, in the rem- nant of the suture of the same name. In the infant the communication is even more free, for this suture does not close until the end of the first year. The canal for the facial nerve passes downwards 96 THE HEAD AND NECK [CHAP. on its inner wall, where the antrum opens into the attic, and behind the facial nerve, also on the inner wall, is the external semicircular canal (Fig. 23). Facial paralysis or giddiness may follow operations on the antrum if the inner wall is injured. The superior and posterior borders of the meatus indicate the position of the facial nerve (Fig. 24); on the inner wall of the sinus or antrum the nerve is situated 14 to 22 mm. deep FACIA r Fig. 24. Showing the position and relationships of the various parts of the middle ear. (See also Fig. 4. p. 15.) to the supramcatal triangle (Joyce). The sinus is separated from the lateral sinus and cerebellum behind by a plate of bone which varies in thick- ness from 3 mm. to 6 mm. It can thus be readily understood why the temporo-sphenoidal lobe, the lateral sinus, and the cerebellum should be the common seats of secondary infection in cases of middle-ear disease. At the mouth of the tympanic sinus and in the attic of the tympanum are situated the incus, the head of the malleus, and their ligaments, structures which may be diseased and require removal. v] TYMPANIC SINUS 97 At birth the outer wall of the sinus is formed by the postmeatal process of the squamosal, a plate of bone 2 mm. thick (Fig. 25). In the child the antrum is comparatively superficial, and pus may easily escape or be evacuated. The suture between the postmeatal part of the squamosal and the petro-mastoid disappears in the second year of life, and so shuts off a possible route that pus may take to reach the surface (Fig. 25). The outer wall of the sinus steadily increases in thickness until SQUAMOSAL POST. I/NF FowTAELLE x ^ ?!f lV^4 DB .AAiT. IMF FOMTANELLE 5QUANO /IASTO SUTURE ^TYMPANIC RlrtQ DRUM 'ST/LO-AIASTOID FORAMEM Fig. 25. Temporal bone at birth. The positions of the tympanic sinus or antrum and attic are indicated. The squamo-mastoid suture is open and the mastoid process undeveloped. adult life, when the depth of the cavity from the surface of the bone is found to vary in different in- dividuals from 12 to 22 mm., about 16 mm. being its average depth. A shallow triangle (see Fig. 24) above and behind the meatus lies directly over the antrum and serves as a guide to its position. It may also IDC reached by following the junction of the posterior wall and roof of the external auditory meatus. The drill is entered 5 mm. behind the meatus and on a level with its upper margin. Its roof lies 5 mm. above the level of the meatus. The E 98 THE HEAD AND NECK [CHAP. posterior auricular artery passes upwards behind the meatus, beneath the concha of the auricle, and lies within the field of any operation on the middle ear. The mastoid cells develop with the growth of the mastoid process, which appears as a definitely marked structure in the second year. Besides the sinus there are also some cells present in the outer wall at birth (Young). During infancy there are two types of mastoid : one in which the bone is dense a form that persists in 1 per cent, of adults; and one in which the mastoid is diploetic a form that is retained in 20 per cent, of adults (A. Cheatle). Three varieties of the mastoid process are recognized in adults, each of which is about equally common: (1) those in which the cells are large and communicate with each other and with the tympanic sinus; (2) those in which the central cells are large and communicate with the sinus, while the peripheral are small and closed; (3) those in which all the spaces are small and closed. The cells surround the sinus, and may pass backwards to the masto- occipital suture, forwards to the suprameatal region, upwards to the masto-parietal suture, and downwards to the apex of the mastoid. Inflamma- tory conditions may lead to a thickening of the walls of the mastoidal cells, and the bone may be- come so dense as almost to resist the chisel. Veins drain into the periosteal veins of the mastoid from the more superficial cells* and by these in- flammation may reach the surface and give rise to oedema and swelling behind the ear. In cases where the outer surface of the mastoid has been spontaneously perforated, a tumour, containing air, has appeared on the skull, and it has been observed that the tumour may be increased in size by forcing air into the ear through the Eustachian tube. Such tumours are known as pneumatoceles, and ^the process that leads originally to the perforation of the bone is of obscure nature. In some cases it seems to have vj EUSTACHIAN TUBE 99 been simply atrophic, and in other instances to have been due to " caries sicca." On the anterior wall of the tympanum is the opening of the Eii*tarlii:tii tube (Figs. 22 and 23). This tube, If inches long, by opening into the pharynx serves to keep a proper supply of air in the tympanum, and so equalize the pressure upon the two sides of the membrane. The floor of the tympanum is below the level of the outer opening of the Eustachian tube. The line of direction of the tube lies almost exactly midway between the trans- verse and antero-posterior axes of the base of the skull. In the adult it inclines downwards, so as to form an angle of 40 with the horizontal. In the child this angle is only 10 (Symington). In adults three-fourths of the tube is cartilaginous and one- fourth bony (Symington). On the outer side lie the tensor palati, the third division of the fifth nerve, and the middle meningeal artery; on the inner side, the retropharyngeal tissue and (quite pos- teriorly) the internal carotid artery. The pharyn- geal orifice of the tube is usually shut. During swallowing, however, it is opened by the action mainly of the tensor palati muscle. If the nose and mouth be closed and the cheeks blown out, a sense of pressure is produced in both ears. The hearing, at the same time, is dulled, and the change is due to the bulging out of the membrana tympani by the air thus forced into the tympanum. This method of inflating the middle ear is known as VaKsalva's method. In Politzer's method of passing air into the Eustachian tube, the patient's mouth is closed, while into one nostril the nozzle of a caoutchouc bag filled with air is introduced, and the nostrils are then held firmly closed. The patient is asked to swallow a mouthful of water, while at the same moment the bag is forcibly emptied, and the air, having no other means of escape, is thus driven into the open Eustachian tube. The surgeon listens for the little noise caused by the entrance of the air by means of a tube that passes between the 100 THE HEAD AND NEGK [CHAP. patient's meatus and his own. Prolonged closure of the Eustachian tube leads to deafness, and thus impairment of hearing may follow upon great thickening of the mucous membrane of the tube due to the extension of inflammatory mischief from the pharynx. In the deafness associated with enlarged tonsils and postnasal growths the hyper- trophic change extends to the mucous lining of the tube, and in many pharyngeaJ growths and nasal polypi the orifice of the tube is mechanically obstructed. The near relation of the pharyngeal end of the tube to the posterior nares serves to explain a case where suppuration in the mastoid cells followed upon plugging of the nares for epistaxis. Infection may be carried up to the middle ear by means of the ciliated lining of the Eustachian tube ; C. J. Bond found that indigo particles, which had been blown within the naso- pharynx, in a case of perforation of the drum, ap- peared afterwards in a discharge from the external meatus. The upper edge of the pharyngeal orifice of the tube is about ^ an inch below the basilar process, \ an inch in front of the posterior wall of the pharynx, \ an inch behind the posterior end of the inferior turbinate bone, and ^ an inch above the soft palate (Tillaux). In the foetus the orifice is below the hard palate ; at birth, on the same level. The form of the opening is that of a triangle. Just behind the elevation formed at the orifice of the Eustachian tube there is a depression in the wall of the pharynx, the pharyngeal recess or fossa of Rosenmuller (Fig. 27, p. 111). It may be mis- taken for the orifice of the tube, and may readily engage the point of a Eustachian catheter. In cases in which the pharyngeal tonsil (Luschka's tonsil) is enlarged, this fossa on either side may bo greatly deepened and made to form a narrow diyerticulum. (See p. 167.) To pass the Eusta- chian catheter, the instrument is carried along the floor of the nares with its concavity down- v] VESSELS OF THE TYMPANUM 101 wards, "until its point can be felt to drop over the posterior edge of the hard palate into the pharynx. The instrument should now be with- drawn until its point can be felt to rise again on the posterior edge of the hard palate; having arrived at this point, the catheter should be pushed onwards about 1 inch, and during its passage its point should be rotated outwards through a quarter of a circle." This mano3uvre should engage it on the orifice of the tube. Blood supply of the tympanum. The arte- ries supplying the tympanum are the tympanic of the internal maxillary and internal carotid, the petrosal of the middle meningeal, and the stylo- mastoid of the posterior auricular. The fact that some of the tympanic veins end in the superior petrosal and lateral sinuses gives another ex- planation of the frequent recurrence of thromboses of those channels in inflammatory affections of the middle ear. The petro-squamous vein, which crosses the roof of the middle ear, also receives branches from the tympanic sinus and attic, and joins the lateral sinus behind and the meningeal veins in front (Cheatle). The lymphatics of the middle ear follow two routes. The majority pass along the wall of the Eustachian tube and end in the retropharyngeal lymphatic gland. Others reach the postauricular group of glands, situated over the mastoid process, by passing out beneath the lining membrane of the meatus and by other efferent channels which accompany the veins escaping by the superficial openings that are seen on the mastoid part of the temporal. The chorda tympani nerve, from its exposed position in the tympanum, is very likely to be damaged in suppurative disease of the middle ear ; and it has been shown that, when this nerve is involved, there may be a disturbance of the sense of taste, which is easily understood when one remembers that some of the nerves of taste reach the tongue by this route. 102 TflE IIF,AB AND The osseous labyrinth is formed independ- ently of the other bony parts of the ear. Portions of this labyrinth have necrosed and have been expelled in recognizable fragments. In a case recorded by Dr. Barr the whole of the osseous labyrinth (the cochlea, vestibule, and semicircular canals) was removed entire as a necrosed frag- ment from the auditory meatus. Suppuration of the middle ear may spread to the inner ear by invading the external semicircular canal the most common route (Scott and West) and eroding the promontory; by the fenestra ovalis, in which the footplate of the stapes is fixed by the strong annular membrane; or by the fenestra rotunda, which is closed by the membrana secundaria. When inflammatory infections spread to the inner ear, two series of symptoms result: (1) disturb- ances of hearing and deafness following the spread of inflammation and suppuration to the cochlea, through the perilymph system (scala vestibuli and scala tympani) ; (2) disturbances of balancing and co-ordination vertigo and vomiting from injury and destruction of the saccule, utricle, and am- pullae of the semicircular canals. The perilymph system of the inner ear gives only too easy a means for the spread of inflammation. From the inner ear the suppurative process may extend inwards along the auditory nerve and meatus, thus reaching the large subarachnoid spaces at the base of the brain. It may also reach the cranial contents by the aqueductus vestibuli or aqueductus cochlea, or by a perforation of the superior semicircular canal. Middle-ear disease may lead to the formation of a fistulous opening in the external semicircular canal. In such cases movements of the head may give rise to nystagmus, for reflex movements of the eyes are influenced by stimuli which arise in the maculae of the semi- circular canals (Sydney Scott). CHAPTER VI THE NOSE AND NASAL CAVITIES THE NOSE THE skin over the root, and the greater part of the dorsum, of the nose is thin and lax. Over the alse, however, it is thick, very adherent to the deeper parts, and plentifully supplied \vith sebaceous and sweat-glands. Inflamma- tion of the integuments over the cartilaginous portion of the nose is apt to be very painful, and to be associated with much vascular engorge- ment. The pain depends upon the tenseness of the part, which prevents it from swelling without pro- ducing much pressure upon the nerves, while the engorgement depends upon the free blood supply of the region, and the fact that, the edge of the nostril being a free border, the circulation there is terminal, and apt therefore to favour con- gestion. The great number of sebaceous glands about the lower part of the nose renders it a favourite spot for acne. It is here that the form of acne termed acne hypertrophica is met with a con- dition that produces the appearance known as " grog blossoms/' The nose, too, is frequently attacked by lupus, and it is over the dorsum of the nose that lupus erythematosus is^ most commonly met with. Rodent ulcer also is apt to appear in this region, especially in the fold between the ala of the nose and the cheek. The integument of the nose is very well sup- plied with blood, and for this reason the part is well suited for the many plastic operations that 103 104 THE HEAD AND NECK [CHAP. are performed upon it. Wounds in this region heal kindly, and even the extensive wound made along the line between the nose and the cheek in removal of the upper jaw leaves very little de- formity. In many reported cases portions of t the nose have been entirely severed, and have united to the face on being immediately re-applied. The skin over the root of the nose is supplied by the nasal branch of the first division of the fifth; as is also the skin over the alse and in the region of the nostril (Fig. 2, p. 11). The greater part of the side of the nose is supplied by the second division of the fifth, and is the seat of pain in neuralgia of that trunk. The fact that the nasal nerve is a branch of the ophthalmic trunk, and has intimate connexions with the eye, serves to explain the lacrimation that often follows painful affections about the nostril, as, for example, when the edge of the nostril is pinched. The cartilaginous part of the nose is often destroyed by lupus, by syphilitic ulceration, and other destructive affections. The parts so lost have been replaced by the various methods in- cluded under the head of rhinoplasty. It is well to bear in mind the limits of the cartilaginous segment of the nose, and to remember that in in- troducing a dilating speculum the instrument should not be passed beyond ^hose limits. In the subjects of inherited syphilis the bridge of the nose is often found to be greatly depressed. This depends upon no actual loss of parts, but rather upon ^ imperfect development from local mal- nutrition, that malnutrition following upon a severe catarrh of the mucous membrane. The de- formity only occurs, therefore, in those who have had " snuffles " in infancy. The nasal bones are often broken by direct violence. The fracture is most common through the lower third of the bones, where they are thin- nest and least supported. It is rarest in the upper third, where the bones are thick and firmly vi] THE NOSE 105 held, and where, indeed, considerable force is required to produce a fracture. Since no muscles act upon the ossa nasi, any displacement that occurs is due solely to the direction of the force. Union takes place after these fractures with greater rapidity than perhaps obtains after frac- ture of any other bone in the body. In one case noted by Hamilton, " the fragments were quite firmly united on the seventh day." If the mucous membrane of the nose be torn, these fractures are apt to be associated with emphysema of the sub- cutaneous tissue, which is greatly increased on blowing the nose. The air in such cases is de- rived, of course, from the nasal fossae. In frac- tures of the upper third of the ossa nasi the cribriform plate may be broken, but it is ques- tionable whether this complication can occur when the fracture is limited to the lower third of the bones. The root of the nose is a favourite place for meningoceles and encephaloceles, the protrusion escaping through the suture between the nasal and frontal bones. Such protrusions, when occurring in this place, are often covered with a thin and vascular integument, and have been mistaken for nsevoid growths. THE NASAL CAVITIES The anterior narcs have somewhat the shape of the heart on a playing-card, and the aperture as a whole measures about li inches vertically, and a little less than l\ inches trans- versely, at its widest part. The plane of the nostril is a little below that of the floor of the nares. To examine the nasal cavities, there- fore, the head should be thrown back and the nose drawn upwards. The anterior nares can be well explored by the finger introduced into the nostril, and the nasal apertures are just so wide on each side of the septum as to allow the finger to be passed far enough back to reach another finger introduced into the posterior nares through the mouth. An effectual way of removing soft 106 THE HEAD AND NECK [CHAP. polypi in the adult is by tearing them away by two fingers so introduced. The operation is a little rough. By the most gentle introduction of the finger into the nostril it is often possible to feel the end of the inferior turbinated bone. ^ The anterior nares, and front of the nasal cavities, can be well explored by Rouge's operation. In this procedure the upper lip is everted, and a transverse cut made through the mucous mem- brane into the soft parts that connect the upper lip with the upper jaw. The incision extends be- tween the second bicuspid teeth of either side. The soft parts connecting the upper lip and nose to the bone are divided without damaging the skin, and the flap is dissected up until the nares are sufficiently exposed. Posterior nares. If a little mirror, some- what similar to that used in laryngoscopy, be cautiously introduced behind the soft palate through the mouth, and illumined from the mouth, the following parts may, in favourable circum- stances, be seen, viz. the posterior nares, the septum, the middle turbinated bone (middle concha), part of the superior and inferior tur- binated bones (conchse), and part of the inferior meatus. The middle meatus is well seen, and also the Eustachian tube, and the mucous mem- brane of the upper part of the pharynx. This mode of examination is very difficult to carry out, and is known as posterior rhinoscopy. The parts just named can all be felt by the finger introduced behind ^the soft palate through the mouth. The posterior nares are often plugged to arrest severe bleeding from the nose, and in order to cut a proper-sized plug it is desirable to bear in mind the dimensions of the apertures. Each aperture is of regular shape, and measures about |^an inch transversely by 1| inches in the vertical direction in a well-developed adult skull. As regards the nasal cavities generally, it is well to note that the floor is wider at the centre than at either end, that the vertical diameter is vi] NASAL CAVITIES 107 greater than the transverse, and is also greatest about the centre of the fossae. Forceps introduced into the nose, therefore, are most conveniently opened if opened vertically. The width of the fossae increases somewhat from above downwards; thus the superior turbinated bone is only 2 mm. from the septum, while a- space of from 4 to 5 mm. intervenes between the inferior turbinated bone and the septum. The nasal cavity is so very narrow above the middle turbinated bone that MlD.TURB. U^P^* WBU-J Fig. 26. Transverse vertical section of the nasal cavities and accessory sinuses. and accessory sinuses that bone really forms the surgical roof of the nasal fossae. The shape and proportions of the nasal cavity in the child are peculiar. In the adult the inferior meatus is large (Fig. 26), and con- stitutes the chief respiratory passage ; in the young child the inferior meatus is relatively very small, the middle meatus affording the main space for the respiratory tide (Lack). The nasal cavities grow rapidly from the sixth to the eighteenth year ; during this period the permanent dentition is being formed, necessarily causing an increase in 108 THE HEAD AND NEGK [CHAP. the size of the palate and of the floor of the nose ; at the same time the development of the maxillary sinus leads to an increase in the vertical height of the nose, this increase affecting the lower or maxillary much more than the ethmoidal or olfac- tory part of the cavity. Growth of the nasal cavities and of the face may be arrested or viti- ated by any obstruction to the free passage of the breath through the nose; the most common cause of obstruction is the formation of adenoids in the naso-pharynx. By referring to the relations of the nasal fossae (Figs. 26, 27) it will be understood that inflam- mation of the lining membrane (coryza) may ex- tend to the pharynx via the posterior nares ; may extend up the Eustachian tube and cause some deafness; may reach the lacrimal sac and con- junctiva through the naso-lacrimal duct; and may extend to the frontal and maxillary sinuses, producing frontal headache and cheekache. These relationships are often demonstrated in a severe " cold in the head." From the nearness of the nasal fossae to the cranial cavity it happens that meningitis has followed upon purulent inflam- mations of the nose. Micro-organisms which give rise to inflammation of the meninges of the brain apparently find their way from the mucous lining of the nose to the cranial cavity along minute blood- and lymph-vessels which traverse the cribri- form plates with the olfactory nerves. Foreign bodies of various kinds are often lodged in the nose, and may remain there for some years. Thus, Tillaux reports the case of an old woman aged 64 from whose nose he removed a cherry- stone that had been there for twenty years. In washing out the nasal cavities with the " nasal douche" the fluid is introduced by means of a siphon. The nozzle of the siphon tube is introduced into one nostril, the mouth is kept open, and the fluid runs through that nostril, passes over the soft palate, and escapes from the other nostril. The latter cavity is therefore vi] NASAL CAVITIES 109 washed out from behind forwards. The course of the fluid depends upon the fact that when the mouth is kept open there is such a disposition to breathe through it alone that the soft palate is drawn up and the nares cut off from the pharynx. The roof of each nasal fossa is very narrow, being only about ^ of an inch in width (Fig. 26). It is mainly formed by the thin cribriform plate, but its width is such that the danger of the roof being penetrated by so large an object as a pair of polyp forceps has been greatly exaggerated. The cranial cavity has, however, been opened up through the roof of the nose by penetrating bodies introduced by accident or with homicidal intent. Meningitis has followed inflammation of the nasal fossae, the inflammation extending through the cribriform plate. Through the perineural and perivascular sheaths the lymphatic system of the nose is in continuity with that of the meninges, and by these channels infections may spread from the roof of the nose to the mem- branes of the brain. Fracture of this part also has been associated with very copious escape of cerebro-spinal fluid through the nostrils. A men- ingocele may protrude through the nasal roof. Tn a case reported by Lichtenberg the mass hung from the mouth, having passed through a congeni- tal fissure in the palate. It was mistaken for a polyp, was ligatured, and death resulted from intracranial inflammation. The septum is seldom quite straight in adults; the deviation being more often towards the left. t It is, however, straight in children, and remains so up to the seventh year. In adults the septum^ deviates in 76 per cent, of all persons. The deviation may follow an injury. It has been pointed out that a deviation of the septum may seriously interfere with the singing voice. The nose also is seldom quite straight, and French authors ascribe this to some deviation of the sep- tum, often dependent upon the practice of always blowing the nose with the same hand. If the 110 THE HEAD AND NEOK [CHAP. deviation of the septum be considerable, it may more or less block one nostril, and, until the oppo- site nostril is examined, be mistaken for a septa! tumour encroaching upon the cavity. The flat- tened nose in acquired syphilis is usually due to destruction of the septum and more or less implication of the adjacent bones. Outer wall (Fig. 27). The inferior nasal concha may interfere with the introduction of a Eustachian catheter if the curve of the instru- ment be too great. The anterior end of the bone is about | of an inch behind the orifice of the nostril. The opening of the naso-lacrimal duct is about 1 inch behind the orifice of the nostril, and about f of an inch above the nasal floor. This opening is usually slit-like and narrow. The nasal duct pierces the nasal mucous mem- brane in the same oblique and valvular manner as the ureter enters the bladder; hence the nose can be blown without inflation of the lacrimal sac. The height of the inferior meatus is about I of an inch. The superior meatus is a very short and narrow fissure, and into its upper and fore part open the posterior ethmoidal cells. The middle meatus opens widely in front upon a part of the outer wall called the atrium, and, unless care be taken to keep the point of any in- strument well towards the floor of the fossa, it is easier to pass the instrument into the middle than into the inferior meatus. Upon the wall of the middle meatus is a deep gutter (the hiatus semilunaris) , which runs from above downwards and backwards (Fig. 27). Into this groove open the frontal sinus by means of the naso-f rental duct, about \ an inch long, the anterior ethmoidal cells, and, near its posterior end, the maxillary sinus. The rounded aperture of the frontal sinus is usually situated in the anterior end of the hiatus, but not infrequently it will be found in a recess above and in front of the hiatus. The anterior ethmoidal cells, usually two in number, mlay open into the hiatus, the naso-frontal duct (infundi- VI] OUTER WALL NASAL CAVITY 111 bulum), or directly into the anterior part of the middle meatus. The opening of the maxillary sinus may occur below, instead of within, the posterior part of the hiatus semilunaris (Fig. 27). The upper boundary of the hiatus is formed by the bulla ethmoidalis ; its lower sharp prominent margin contains the uncinate process of the eth- moid. The middle ethmoidal cell is seen to open PiTUITABy FOSSA Fig. 27. Outer or lateral wall of the nasal cavity. The greater part of the middle turbinate process has been cut away to expose the hiatus, bulla, and opening of the infundibulum or nasp-frontal duct and maxillary sinus. A, B, indicate the two positions at which the opening of the antrum may occur. on the bulla, above the hiatus semilunaris. The level of the hiatus within the nose may be indi- cated by the position of the internal palpebral ligament. The anterior end or beak of the middle turbinate process can be seen distinctly from the anterior nares, when the interior of the nose is illuminated by reflected light. The width of the nasal floor is about \ an inch, or a little over. Its smooth surface greatly 112 THE HEAD AND NECK [OHAP. favours the passage of instruments (Fig. 26). It presents a gentle slope from before backwards. At its anterior part is a depression of mucous membrane over the incisor foramen. This foramen is a vestige of the great communication that once existed between the cavities of nose and mouth. The mucous membrane lining the nasal cavi- ties is covered with ciliated epithelium over the lower two-thirds or respiratory part; the upper third the olfactory part is covered with colum- nar epithelium, while the vestibule is lined with stratified epithelium. It is very thick and vas- cular over the turbinate bones and over the lower two-thirds of the septum, while over the nasal floor and in the intervals between the turbinate bones it is very much thinner. The mucous membrane lining the various sinuses and the antrum is conspicuously thin and pale. The membrane is provided with many glands, which are most conspicuous over the lower and hinder parts of the outer wall and over the posterior and inferior parts of the septum. These glands may be the subject of considerable hypertrophy. They are capable of providing also a very copious watery secretion, which has in some cases of chronic coryza following injury been so free as to be mistaken for an escape of cerebro-spinal fluid. There is also much adenoid or lymphoid tissue in the nasal mucous membrane, which is the primary seat of the chief scrofulous affec- tions that invade this part. So thick and lax is the normal mucous membrane over the lower border and posterior extremity of the inferior turbinated bones, that it forms a kind of soft cushion, sometimes called the " turbinate body." This condition is mainly due to the presence of a rich submucous venous plexus, the vessels of which run, for the most part, in an antero-posterior direction. When turgid with blood it swells so as to obliterate the interval between the bone and the septum. When the seat of chronic inflam- mation, the mucous membrane over the inferior vi] POLYPI 113 bone may appear as a polypoid swelling. The inspired air is heated as it passes over the rich vascular lining membrane of the nose; it is also filtered, the dust and other floating particles being deposited on the moist surface of the conchse. Polypi are often met with in the nose. They are of two kinds, the mucous or myxoraatous polyp that springs usually from the mucous mem- brane beneath or over the middle concha, and the fibrous or sarcomatous polyp that usually takes origin from the periosteum of the nasal roof or from that of the base of the skull. Polypi of the latter kind spread in every available direc- tion. They expand the bridge of the nose, close the nasal duct and cause epiphora, depress the hard palate and encroach upon the mouth, in- vade the antrum and expand the cheek, grow down into the pharynx, pushing forwards the velum palati, and may penetrate even through the inner wall of the orbit. Such tumours may be exposed and removed by separating the posterior and inner attachments of the superior maxilla, turning it forwards, thus exposing the nasal cavity by detaching its outer wall. The bone may be replaced in situ after removal of the tumour. The foloocl supply of the nasal cavity is extensive, and is derived from the internal maxillary, ophthalmic, and facial arteries. With regard to the veins, it may be noted that the ethmoidal veins that come from the nose enter the ophthalmic vein, while it is believed by some authorities that in children a constant commu- nication exists between the nasal veins and the superior longitudinal sinus through the foramen caecum, and that this communication may be maintained in the adult. These connexions would, in part, explain the occurrence of intracranial mischief as a consequence of certain inflammatory affections of the nasal cavities. Bleeding from the nose, or epistaxis, is a common and often a serious circumstance. Its frequency is to a great extent due to the vascularity of the mucous 114 THE HEAD AND NEOK [CHAP. membrane, to its laxity, and to the fact that the veins, especially those over the lowest (maxillary) turbinate bone, form extensive plexuses, and pro- duce a kind of cavernous tissue. The epistaxis is often due, therefore, to interference with ^the venous circulation, as seen in cases of cervical tumour pressing upon the great veins, in the paroxysms of whooping-cough, and the like. The beneficial effect of raising the arms in epistaxis is supposed to depend upon the extra expansion of the thorax so produced, and the aspiratpry effect thus brought to bear upon the cervical veins. The bleeding may be copious and long continued. Thus, Spencer Watson reports a case where the epistaxis continued on and off for twenty months without obvious cause. Martineau mentions an instance in which 12 Ib. of blood was lost in sixty hours, and Fraenkel records a case where 75 Ib. of blood is said to have escaped from first to last. In several instances the haemorrhage has proved fatal. The seat of the bleeding is often not easy to detect, even when the examination is post mortem. In many cases the bleeding-point is situated on the septum, ^ an inch above and behind the nasal spine. The nerve supply of these parts is derived from the olfactory nerve, and from the first and second divisions of the fifth nerve. The lacrimation that often follows the introduction of irritants into the nares may be* explained by the fact that that part of the cavity is sup- plied freely by the nasal nerve, a branch of the ophthalmic trunk. As an example of transfer- ence of nerve force in the opposite direction may be noted cases where a strong sunlight falling upon the eyes has produced an attack of sneez- ing. Troubles involving the vagal centres, such as cough and bronchial asthma, have followed affections of the nasal cavities; relief from these troubles has been obtained by cauterization and anesthetization of the mucous membrane over the inferior concha. The olfactory nerves are vi] NASAL SINUSES 116 situated in the upper third of the cavity, and hence, in smelling intently, one sniffs deeply and dilates the nostril. The inability to dilate the nostril in facial paralysis may explain the par- tial loss of smell sometimes noted in such cases. Anosmia, or loss of the sense of smell, when fol- lowing upon an injury to the head, may be due to a rupture of the olfactory nerve fibres as they pass through the cribriform foramina. The olfactory roots cross the edge of the lesser wings of the sphenoid, and in falls on the forehead are liable to injury. The olfactory centre is situated in the hippocampal gyrus. Most of the lymphatics of the nasal fossss enter the retropharyngeal glands placed behind the pharynx, in front of the rectus capitis anti- cus major. Hence, as Fraenkel has pointed out, " retropharyngeal abscess may arise in conse- quence of diseases of the nose." Other lympha- tics go to the submaxillary, parotid, and upper deep cervical lymph-glands, and it is common to find these enlarged in nose affections, especially in the scrofulous. The lymphatics of the nose also communicate with those of the meninges through the cribriform plate. Nasal sinuses. Of late years a knowledge of the anatomy and relationships of the ac- cessory sinuses of the nose has become of the utmost importance to the surgeon. Over 15 per cent, of the subjects examined in the dissecting room of the London Hospital show disease of one or more of these sinuses; Sir StClair Thomson estimates that the sphenoidal sinus is the seat of disease in 30 per cent, of aged individuals. The collective capacity of the accessory sinuses the maxillary, frontal, sphenoidal, and ethmoidal is more than twice that of the nasal cavity (Braune). No satisfactory explanation has yet been found of their use, except to give mass without adding to the weight of the face. They may, as Dr. James Adam has supposed, aid in rendering the inspired air warm and moist. 116 THE HEAD AND NECK [CHAP. The frontal sinus is extremely variable in size and shape. The surface markings shown in Fig. 28 indicate the average development in the adult; the opening of the fronto-nasal duct or infundibulum is shown in Fig. 27. Large frontal sinuses do not necessarily imply large external prominences Fig. 28. Surface markings of the frontal and maxillary sinuses. A, Ij " above the nasion ; B, on the supraorbital margin, at the junction of the middle and outer thirds ; C, on the infraorbital margin to the outer side of the lacrimal sac ; D, on the centre of the cheek-bone in line with the outer margin of the orbit ; E, over the second bicuspid ; F, over the last molar. The points A, B, and Nasion give the surface position of the frontal sinus ; C, D, E, F, that of the maxillary sinus. over the glabella and superciliary eminences. One sinus may develop at the expense of the other, vi] FRONTAL SINUS 117 and the septum may be displaced. They are larger in men than in women. They are absent on one side in 9 per cent, of cases, and on both sides in 7 per cent. (Logan Turner). It is obvious that a depressed fracture may exist over a frontal sinus without the cranial cavity being damaged. In such cases the inspissated contents of the sinus have been mistaken for brain matter escaping. Since the sinuses are in communication with the nose, much emphysema may follow upon the fracture of the sinus wall. Insects have found their way into these cavities. " Centipedes are particularly liable to be found in the frontal sinuses, where they may remain for years, the secretions of these cavities furnishing them with sufficient nourishment " (Fraenkel). Larvae have also been found here, and maggots that have developed within the nose have managed to make their way to the frontal sinuses. The frontal sinus is merely a bud or rudiment in early childhood. About the sixth year the bud of mucous membrane grows out from the neigh- bourhood of the anterior end of the hiatus, and gradually insinuates its growing extremity into the diploe of the frontal bone, separating the inner from the outer osseous table. It reaches its full size about the twenty-fifth year ; the stalk of the outgrowth becomes the fronto-nasal duct; it leads from the posterior part of the sinus. The duct is | of an inch long, and runs downwards and slightly backwards to open at or near the anterior end of the hiatus semilunaris. Along the hiatus the secretion of the frontal sinus may be conveyed to the antrum, thus converting that cavity into a cesspool in cases of chronic suppura- tion of the frontal sinus (Fig. 27). The fronto- nasal duct is frequently tortuous, and even after the beak of the middle turbinate process is removed it is not easy to catheterize from below. Hence, in cases of obstruction, the frontal sinus is trephined over the glabella, or at the superior internal angle of the orbit (Tilley), and a probe passed down- 118 THE HEAD AND NECK [CHAP. wards and slightly backwards to drain the sinus into the nose. The anterior ethmoidal cells commonly open into the fronto-nasal duct, and hence they are usually involved in any disease affecting the frontal sinus. The frontal diploic vein, which joins the frontal vein at the supraorbital notch, receives blood from the frontal sinus. In cases of frontal suppuration, infection may spread rapidly in the frontal bone by means of the veins of the diploe, setting up a destructive form of osteitis and meningitis. The sphenoidal sinus opens on the roof of the nose, behind the superior meatus (Fig. 27) ; it is developed at the same period of life as the frontal sinus. It is deeply placed, and not very accessible for operation when the seat of disease. It is frequently the seat of chronic suppuration set up by infections from the nose. Its anterior wall, which is comparatively thin, is situated be- tween 7 and 8 cm. from the lower margin of the anterior nares. Tilley recommends the mid-point of the lower border of the middle turbinate as a guide to the opening of the sphenoidal sinus. The nasal septum also serves as a safe guide, for its vomerine part is implanted on the anterior wall of the sinuses. A probe directed to this point from the floor of the anterior nares will, if passed straight onwards, reach the opening of the sinus at the depth mentioned above 7 to 8 cm. In close contact with the thin lateral wall of this sinus there ^are certain extremely important struc- tures ; Besides the cavernous sinus and internal carotid artery, the optic nerve and second division of the fifth nerve are in the closest contact, and may be affected in sinusitis (Fig. 32, p. 131). On the roof is the pituitary body; tumours of this body may invade the sinus. Its veins join the ethmoidal. The walls of the sinuses are thin and easily perforated, as a case which occurred at the London Hospital will show. A man stumbled vi] MAXILLARY SINUS 119 forwards on his umbrella as he left a public- house in Whitechapel, the point entering his face above the bicuspid teeth. He walked to the hospital, and died three days afterwards. The ferrule of the umbrella was found embedded in the pons, the point having traversed the maxillary and sphenoidal sinuses. The maxillary sinus (antrum of Highmore) exists at birth, but attains its largest dimensions in old age. The surface markings for indicating its position on the face are given in Fig. 28. The walls of the cavity are thicker in children than in adults. Tumours of various kinds are apt to develop in this cavity, and to distend its walls in various directions. Thus the growth breaks through the thin inner wall and invades the nose, it pushes up the roof of the cavity and invades the orbit (see Fig. 26, p. 107), it encroaches upon the mouth through the floor of the sinus, and makes its way also through the somewhat slender anterior wall into the cheek. The densest part of the sinus wall is that in relation to the malar bone, and this part does not yield. There is little inducement for any growth to spread backwards, although it sometimes invades the zygomatic and pterygo-maxillary fossae. As the infraorbital nerve runs along the roof of the sinus, while the nerves of the upper teeth are connected with its walls, these structures are pressed upon in growths springing from the sinus, and thus neuralgia of the face and teeth is often produced. In individuals who have suf- fered from adenoids the growth of the sinus is arrested. In the operation of tapping the antrum a ^spot is usually selected just above the second bicus- pid^ tooth, since the bone is here thin and is con- veniently reached. In some cases it is sufficient to extract one of the molar teeth, since the fangs of these often enter the cavity of the sinus. The tooth usually selected is either the first or the third molar. Not infrequently the sinus com- 120 THE HEAD AND NECK municates at its upper anterior part with the frontal sinus. From Fig. 26 it will be seen that the antra descend below the level of the palate, and cannot be efficiently drained by an opening made above t the palatal level. The opening of the maxillary sinus is shown in Figs. 26, 27; it is on a level with the roof of the cavity : hence if pus be present it drains most freely when the head is turned so that the affected chamber is uppermost. The sphenoidal sinus empties most easily when the head is bent forwards; the frontal, when the head is thrown backwards. The cavity of the antrum is small if the inferior meatus is large or if the canine fossa of the face is well marked. The lymphatics of the sinuses drain into the retropharyngeal glands. As the result of a fall, one of the upper teeth has been entirely driven into the antrum and lost to view. In one case an upper incisor was found lying loose in the antrum three and a half years after the accident that had driven it there. CHAPTER VII THE FACE THE parts of the face, other than those already dealt with, will be considered under the fol- lowing heads : 1. The face generally. 2. The parotid region. 3. The upper and lower jaws, and parts con- nected with them. The lips will be considered with the cavity of the mouth (Chap. vin.). 1. THE FACE GENERALLY The skin of the face is thin and fine, and is more or less intimately adherent by a deli- cate subcutaneous tissue to the parts beneath. The skin generally is very freely supplied with sebaceous and sudoriparous glands, and hence the face is frequently the seat of acne, an eruption that especially involves the sebaceous follicles. From the thinness of the skin, and from the absence of dense fasciae, facial abscesses usually soon point and seldom attain large size. The cellular tissue of the face is lax, and readily lends itself to spreading infiltrations, so that in certain inflammatory affections the cheeks and other parts of the face may become greatly swollen. In general dropsy, also, the face soon becomes "puffy," the change first appearing as a rule in the lax tissue of the lower eyelid. The skin over the chin is peculiarly dense and adherent to the parts beneath, and in most respects closely resembles the integument of the scalp. When such 121 122 THE HEAD AND NECK [CHAP. parts of the integuments of the face as cover prominent bones, such as the malar bone, chin, and the supraorbital margin, are struck by a blunt instrument or in a fall, the wound pro- duced has often the appearance of a clean incised wound, just as obtains in contused wounds of the scalp. The mobility of the facial tissues renders this part very suitable for the performance of plastic operations of various kinds, and their vascularity generally ensures a ready and sound healing. Although there is a large quantity of fat in the subcutaneous tissue of this region, fatty tumours are singularly rare upon the face. They appear, indeed, to avoid this region. Thus, M. Denay reports the case of a man who had no fewer than 215 fatty tumours over different parts of his body, but not one upon his face. The face is peculiarly liable to be the seat of certain ulcers, especially rodent and lupous ulcers, and is the part most often attacked by malignant pustule (anthrax), a disease transmitted to man from cattle afflicted with a malady known in this country as splenic fever, and in France as char b on. Blood supply. The tissues of the face are very vascular, and are liberally supplied with blood-vessels in all parts. The facial arterioles have a particularly rich supply of vaso-motor nerves, which are derived from the sympathetic system, reaching the facial artery through the superior cervical ganglion. In blushing, the vaso-dilator fibres are stimulated by an emotional disturbance. The finer vessels of the skin often appear permanently injected or varicose in the drunken, or in those who are much exposed to cold, or are the subjects of certain forms of acne. Nsevi and the various forms of erectile tumour are common about the face. For a like reason also wounds of the face, while they may bleed readily when inflicted, are apt to heal with singular promptness and accuracy. All vii] BLOOD SUPPLY OF THE. FACE 123 wounds, therefore, of this part should have their edges carefully adjusted as soon after the accident as possible. Extensive flaps of skin that have been torn up in lacerated wounds often retain their vitality in almost as marked a manner as do like flaps torn from the scalp. Extensive injuries to the face associated with great loss of substance are often repaired in a remarkable manner, and such injuries may not be immediately fatal, as a case reported by Longmore shows : "An officer of Zouaves, wounded in the Crimea, had his whole face and lower jaw carried away by a ball, the eyes and tongue included, so that there remained only the cranium, supported by the neck and spine." He lived twenty hours. The pulsations of the facial artery can be best felt at the lower border of the jaw, where the vessel crosses just in front of the anterior border of the masseter muscle. It is here covered only by the integument and the platysma, and can be readily compressed against the bone or ligatured. The anastomoses of the artery upon the face are so free that, when the vessel is divided, both ends, as a rule, require to be secured. The facial vein is only in contact with the artery near the lower border of the jaw ; on the face it is separated from it by a considerable interval. The vein is not so flaccid as are most superficial veins; it remains more patent after section, it possesses no valves, and communicates at one end indirectly with the cavernous sinus, and at the other with the inter- nal jugular vein in the neck. This vein has also another, but less direct, communication with the intracranial veins. It is as follows : the facial vein receives the "deep facial vein" from the ptery- goid plexus, and this plexus communicates with the cavernous sinus by means of some small veins which pass through the foramen ovale and the fibrous tissue of the foramen lacerum medium. These dispositions of the facial vein may serve to explain the mortality of some inflammatory affections of the part. Thus, carbuncle of the face 124 THE HEAD AND NECK [CHAP. is not infrequently fatal by inducing thrombosis of the cerebral sinuses, and a like complication may occur in any other diffuse and deeply extend- ing inflammatory condition. A reference to the development of the face assists to explain the distribution of the fifth nerve and the occurrence of certain abnormalities (Fig. 29). The face is developed from five pro- cesses, a mesial, the fronto-nasal, and two lateral the maxillary and mandibular. The fronto Fig. 29. - Showing the development of the face. F.N.P., Part formed from the fronto-nasal process ; L., from its lateral, and M., from its mesi;il parts ; MAX., formed by the maxillary process ; MAN., formed by the mandibular process. nasal process forms the middle part of the upper lip and the nose. It may fail to develop : thus the condition of cyclops is produced. It springs from the frontal region and carries with it a branch of the first division of the fifth, the nasal nerve. The second division of the fifth is the nerve of the maxillary process, while the third is that of the mandibular. JVerve supply. The nerves of the face are very liberally distributed, the fifth being the vii] NERVE SUPPLY OF THE FACE 125 sensory nerve, the facial the motor (Fig. 2, p. 11). It follows, from the great number of nerve fila- ments about the part, and the extensive sensory nucleus of the fifth nerve, that severe irritants applied to the face may set up a widespread nerve disturbance (Fig. 31, p. 129). Dr. George Johnson mentions a case where a piece of flint embedded in a scar on the cheek set up facial neuralgia, facial paralysis, and trismus, and induced a return of epileptic attacks. The positions of the supra- and infraorbital foramina and of the mental foramen and of the exit of the corresponding nerves are indi- cated as follows : The supraorbital foramen is found at the junction of the inner with the middle third of the upper margin of the orbit. A straight line drawn downwards from this point so as to cross the gap between the two bicuspids in both jaws will cross both the infraorbital and mental foramina. The infraorbital foramen is a little over \ of an inch below the margin of the orbit. The mental foramen in the adult is midway be- tween the alveolus and the lower border of the jaw, and is a little over of an inch below the cul-de-sac of mucous membrane between the lower lip and jaw. At puberty the foramen is nearer fco the lower border of the maxilla, and in old age it is close to the alveolus. The infraorbital nerve has been divided for neuralgia at its point of exit, the nerve being reached either by external incision or through the mouth by lifting up the cheek. In other cases the floor of the orbit has been exposed, the infraorbital canal (the anterior half of which has a bony roof) has been opened up, and large portions of the trunk of the nerve have been in this way resected. The spheno-palatine (Meckel's ganglion) has been repeatedly excised for the relief of neuralgia involving the second division of the fifth nerve. A triangular flap of skin is turned up from the front of the cheek, and the infra- orbital foramen is exposed. The anterior wall of the antrum is opened with a trephine, and the bone 126 THE HEAD AND NECK [CHAP is cut away from the floor of the infraorbital groove so that the nerve lying in that canal is fully exposed. The nerve is followed back to the posterior wall of the antrum. This wall having been trephined, the spheno-maxillary (pterygo- palatine) fossa is opened up and Meckel's ganglion exposed (Fig. 30). Beyond the ganglion the fora- men rotundum can be made out. The infraorbital artery runs with the nerve, and that vessel, to- 3RD DlV, EXT. PTERYGOID PLATE \ SPHENO-MAX. FOSSA Fig. 30. Surface markings for the second and third divisions of the fifth nerve. gether with its anterior dental branch to the incisor and canine teeth, will probably be divided. The infraorbital vein ends in the pterygoid plexus. The ganglion is surrounded by the ter- minal branches of the internal maxillary artery. It is a triangular body, with a diameter of about i of an inch. It is a little convex on its outer side, and is of reddish colour. Operations such as that just described serve to recall the relationship of parts, but in practice vn] NERVE SUPPLY OF THE FACE 127 they are now replaced by the simpler means of hypodermic injections. Absolute alcohol, in- troduced into the trunk of a nerve, produces anaesthesia in the area of its distribution for six months or more. The successful performance of such injections requires a very accurate knowledge of the position and course of the nerves, and also of surrounding structures. The course of the second division of the fifth nerve is shown in Fig. 30. A point on the upper border of the zygoma, 6 mm. (| inch) behind the ascending margin of the malar, lies directly over the upper part of the spheno-maxillary fossa which con- tains the second division of the fifth nerve and Meckel's ganglion. To reach the nerve the needle has to be introduced 37 mm. (1^ inches). An easier and safer route is along the floor of the orbit. The needle is inserted at the mid-point of the lower border of the orbit, and pushed back- wards along the floor, parallel to the sagittal plane of the head. The needle is pushed within the spheno-maxillary fossa until it is arrested by coming in contact with the sphenoid at or near the foramen rotundum. By suitable manoeuvring the needle can be felt to enter the foramen rotundum. The depth of the foramen rotundum from the margin of the orbit is 43 mm. (If inches). The nerve may also be reached by introducing the needle at the upper border of the zygoma just behind the malar angle, and directing it inwards. The ganglion lies at a depth of 50 mm. (2 inches) from the surface (Symington). The inferior dental nerve has been divided at the mental foramen by an incision made through the buccal mucous membrane opposite to the roots of the two premolar teeth. Through this incision the nerve can be stretched and the cuta- neous portion of it excised. The nerve has been divided in the following manner before its entry into the mandibular (inferior dental) ^foramen^: The mouth being held widely open, an incision is made from the last upper molar to the last lower 128 THE HEAD AND NECK [CHAP. molar just to the inner side of the anterior bor- der of the coronoid process, which can be clearly denned by palpation. The cut passes through the mucous membrane down to the tendon of the tem- poral muscle. The finger is introduced into the incision, and passed between the ramus of the jaw and the internal pterygoid muscle until the bony point is felt that marks the orifice of the mandibular (inferior dental) canal. The nerve is here picked up with a hook, isolated, and divided. The buccal nerve supplies the mucous membrane and skin of the cheek. It passes forwards on the outer surface of the buccinator muscle. The trunk of the third division of the fifth nerve leaves the middle fossa of the skull by the foramen ovale, the position of which corresponds to the lower border of the zygoma immediately anterior to the eminentia articularis (Fig. 30). To inject the trunk of the nerve, the needle is entered at this point and guided inwards against the under surface of the sphenoid until a depth of 37 mm. (1^ inches) is reached. Sensations referred along the nerve will tell the operator if the nerve has been reached. It is well to direct the needle a little forwards as well as inwards, for it will be then arrested by the external pfcerygoid plate; at the posterior border of this plate lies the foramen ovale. It is also possible, by directing the needle in a more upward and backward direction, to enter the foramen ovale and reach the Gasserian (semilunar) ganglion itself (see Fig. 32). When a sensory nerve is divided, the area of analgesia which results does not correspond to its anatomical distribution. Thus, when the ophthalmic division of the fifth cranial nerve is cut, only a narrow strip of skin on the forehead is completely deprived of feeling, whereas from the anatomical distribution one would infer that the skin of the forehead and of the anterior half of the scalp would be involved (see Fig. 2, p. 11). If vn] DIVISION OF A SJENSORY NERVE 129 the second division is cut, the area of anaesthesia is confined to a narrow space between the orbit and the mouth; on section of the third division,, to a strip running downwards in front of the ear and along the course of the lower jaw (Head). Head has offered an explanation of the. vary- ing results which follow section of a sensory nerve. A nerve contains three kinds of sensory nerve fibres : (1) those subserving deep sensibility endowing muscles, bones, ligaments, joints, and deep structures with the power to feel pressure and B; Fig. 31. Diagnosis showing the extent of loss of sensi- bility following (A) excision of the Gasserian gang- lion, (B) section of the second cervical nerve. (After H. H. Tooth.) In the area stippled black there is a loss of protopathic sensibility ; in that stippled red, of epicritic sensibility. pain ; (2) those subserving protopathic sensibility by which the skin is rendered, sensitive to prick, and to temperature if it be above 40 or below 22; (3) those subserving epicritic sensibility by which the skin is endowed with the power of feeling light touch (tested with such a substance as cotton- wool) and finer degrees of temperature. Now, in the majority of instances, when a nerve is divided, the loss of epicritic sensibility corresponds in extent to the anatomical distribution of the nerve; when 130 THE HEAD AND NECK [CHAP. the semilunar or Gasserian ganglion is removed (see Figs. 2 and 31), the loss of epicritic sensibility corresponds to the area of distribution, but the loss of protopathic sensibility is less than the anatomi- cal area. It is evident that protopathic fibres from the second cervical nerve (Fig. 31) invade and sup- ply the area of skin furnished with epicritic sen- sibility by the fifth nerve. In the lower part of the face there is no overlapping of areas ; in the mental branch of the fifth, the epicritic and protopathic fibres are distributed to the same extent of skin. Thus th6 effects which follow section of a sensory nerve depend on the nature of the fibres in that nerve, and on the extent of skin to which each kind is exclusively distributed. Even after the semilunar ganglion is excised, the deep structures of the face are sensitive to pressure; that is due to the facial nerve containing certain afferent fibres which are sensitive to pressure (Maloney and Kennedy). Excision of the Gasserian ganglion. For cases of intolerable and intractable neuralgia Kose pro- posed the excision of the semilunar ganglion. It is the sensory ganglion of the fifth nerve, and corresponds to the ganglion on the posterior root of a spinal nerve. The nerve fibres of the fifth necessarily undergo degeneration when it is excised. The operation usually performed is the follow- ing (see Fig. 32) : An omega-shaped flap of skin is raised from the temples, having the zygoma at its base and the temporal ridge at its convexity. The tissues are reflected down to the floor of the temporal fossa. The superficial and deep temporal vessels have to be tied. A wide trephine opening is made in the squamosal and great wing of the sphenoid on a level with the upper border of the zygoma, and the dura mater exposed. This is usually followed by profuse haemorrhage from the middle meningeal vessels which cross the field of operation. The dura mater and the superimposed temporo-sphenoidal lobe are raised from the bone, vii] EXCISION OF GASSERIAN GANGLION 131 when the third and second divisions of the fifth nerve are brought into view as they escape by the foramen ovale and foramen rotundum. They are seen to spring from the ganglion situated over the apex of the petrous bone and on the outer wall of the cavernous sinus. The motor root which supplies the muscles of mastication lies under the ganglion and should not be cut. The ganglion is embedded in the dura mater and sur- rounded by a prolongation of the subarachnoid ISLAND of BEIL * FISSURED DEEP TCMP.FASCIA TEMP MUSCLE FIRST TBM UMCUS DURA MATER fliD MenmCEALAR ROOT of ZYQONA EXT, PTER/QOID MlO flE IAT. MAT.. ART MASSETER __- - CORONOID PROC . OPTIC TRACT 5UBARACH/10ID SPACE IV* 1 CAVER/IOUS 5i/ius I/IT CAROTID ART. VI th QASSERIAM qAnqtiO SPHEROIDAL SINUS 3' d DIV OF V fh LAT. RECESSopPrtAR EUSTACHIA/I TUBB- LEVATOR PAUATAE Fig. 32. Coronal section to show the depth and relation- ships of the Gasserian or semilunar ganglion. space (Meckcl's space), which is necessarily opened. Only the part of the ganglion connected with the second and third divisions is removed, the part connected with the ophthalmic division being left, as it is firmly embedded in the outer wall of the cavernous sinus and inclose proximity to the inter- nal carotid artery and the oculo-motor nerves. The hippocampal convolution containing the olfac- tory centre lies immediately over the ganglion (Fig. 32). There is always an escape of cerebro- 132 THE HEAD AND NEGK [CHAP. spinal fluid when the dural sheath is opened (Cushing). The eminentia articularis at the base of the zygoma serves as a useful guide to the position of the ganglion ; when the middle fossa is opened and^ the temporal lobe raised up, the ganglion will be found at a depth of 2^ inches and in the same Sl/PHA- ORBITAL N. FRONTAL /VASAL /V. NASAL BRMCH fSENSORy) Fig. 33. Diagram to show the proximity of the sensory nuclei of the fifth and tenth cranial and first and second cervical nerves. (After Peglcr.} coronal plane as the articular eminence, but at a higher level.* To understand the various pains which arc so frequently referred to areas supplied by the great fifth nerve neuralgias, headache, migraine, * For a full account of the anatomy of this operation see " The Surgical Treatment of Facial Neuralgia," by J. Hutchinson, jun. London, 1905. vn] THE PAROTID GLAND 133 etc. it is necessary to realize some of the central connexions of the sensory nucleus in which its afferent fibres terminate. That centre extends (see Fig. 33) to the lower part of the medulla oblongata, and is continuous with the posterior horn of the spinal grey matter, in which the sensory fibres of the occipital and other cervical nerves end. Near by is the sensory nucleus of the vagus. Dis- turbances of the vagal centres can overflow and affect the sensory nuclei of the fifth, the pain being usually referred to the distribution of that nerve to the dura mater. Each division of the fifth nerve sends a branch to the dura mater. Malar bone. Such is the firmness of this bone, and so direct is its connexion with the skull, that violent blows upon it are very apt to be asso- ciated with concussion. Resting as it does upon comparatively slender bones, it is very rare for the malar bone to be broken alone. It may, indeed, be driven into the superior maxillary bone, fracturing that structure extensively, without being itself in any way damaged. A fracture of the malar bone may lead to an orbital ecchymosis, precisely like that which often attends a fracture of the skull base. 2. THE PAROTID REGION The deep part of the parotid gland is lodged in a definite space behind the ramus of the lower jaw (Fig. 34). This space is increased in size when the head is extended, and when the inferior maxilla is moved forwards, as in protruding the chin. In the latter movement the increase in the antero-posterior direction is equal to about f of an inch. It is diminished when the head is flexed. When the mouth is widely opened the space is diminished below, while it is increased above by the gliding forwards of the condyle. These facts should be borne in mind in operating upon and in exploring the parotid space. It will be found also that in inflammation of the parotid much pain is produced by all those move- 134 THE HEAD AND NECK [CHAP. ments that tend to narrow the space occupied by the gland. The obliquity of the ramus of the jaw in infancy and old age causes the lower part of the space to be, in the former instance relatively and in the latter instance actually, larger than it is in the adult. The larger part of the gland is superficial and ex- tends over the masseter muscle. The gland is closely invested by a fascia derived from the cer- vical fascia. The super- ficial layer of the parotid fascia is very dense, continuous be- hind with the fibrous Fig. 34. Horizontal section through one side of the face and neck just above the level of the lower teeth. (Braune.) a, Facial artery ; b, facial vein : <\ gustatory nerve ; d, inferior dental nerve and artery lying internally to the ascending ramus of jaw ; t, styloid pro- cess : /. internal carotid artery ; (h internal jugular vein, with the vagus, spinal accessory, and hypoglossal nerves to its inner side ; h, vertebral artery. Externally to the ascending ramus is shown the masseter : internally to it the internal pterygoid ; internally to the last-named muscle, the supe- rior constrictor and tonsil. sheath of the sterno-mastoid, and in front with that of the masseter. Above it is attached to the zygoma, while below it joins the deep layer. The deep layer is slender, is attached to the etyloid process, forms the stylo-maxillary liga- vn] THE PAROTID GLAND 135 ment, and is connected with the sheaths of the pterygoid muscles and the pterygoid process. The gland is, therefore, encased in a distinct sac of fascia, which is entirely closed below, but is open above. Between the anterior edge of the styloid process and the posterior border of the internal pterygoid muscle there is a gap in the fascia, through which the parotid space com- municates with the connective tissue about the pharynx. It is well known that in postpharyngeal abscesses there is very usually a parotid swelling, and in several instances the pus, or at least some portion of it, has been evacuated in the parotid region. In these cases the matter most probably extends from the pharyngeal to the parotid region through the gap just described. From the disposi- tion of the fascia it follows that very great resist- ance is offered to the progress of a parotid abscess directly outwards through the skin. The abscess often advances upwards to the temporal, or zygo- matic fossae, in the direction of least resistance, al- though progress in that line is resisted by gravity. It frequently makes its way towards the buccal cavity or pharynx, or it may break through the lower limits of the fascia and reach the neck. It must be borne in mind that the gland is in direct contact with the cartilaginous meatus, with the ramus of the jaw and other bony parts, and is closely related to the temporo-maxillary joint. Thus, a parotid abscess has burst into the meatus, has led to periostitis of the bones adjacent to it, and has incited inflammation in the joint of the lower jaw. In several cases reported by Virchow the pus appears to have found its way into the skull along branches of the fifth nerve, for the environs of the semilunar ganglion were found infiltrated with pus. The auriculo-temporal and great auricular nerves supply the gland with sensation, and the presence of these nerves, together with the unyield- ing character of the parotid fascia, serves to explain the great pain felt in rapidly growing 136 THE HEAD AND NECK [CHAP. tumours and acute inflammation of the gland. The pain is often very distinctly referred along the course of the auriculo-temporal nerve. Thus, a patient with parotid growth under my (F. T.'s) care had pain in those parts of the pinna and temple supplied by the nerve, pain deep in the meatus, at a spot that would correspond to the entrance of the ineatal branch of the nerve, and pain in the joint of the lower jaw, which is supplied by the auriculo-temporal. The most important structures in the gland are the external carotid artery, with its two terminal branches, and the facial nerve. The external carotid artery, as Tillaux has pointed out, is behind the ramus of the jaw, as high up as the junction of the inferior with the middle third of its posterior border. It then enters the parotid gland, and, passing a little backwards and outwards, comes nearer to the surface, and at the level of the condyle of the jaw breaks into its two terminal branches. The artery, therefore, does not enter the gland at its inferior border, and is not in actual relation with the parotid space at its lowest part. The vessel, more- over, is not parallel with the edge of the ramus, but passes through the parotid gland with some obliquity. At its point of exit from the base of the skull by the stylo-mastoid foramen, the facial nerve lies 1 inch deep to the mid-point of the anterior border of the mastoid process; a line drawn horizontally forwards from that point to the posterior border of the ascending ramus of the mandible marks the position of the main trunk of the nerve (Fig. 35). Within the gland, where ^the nerve divides into its temporo-facial and cervico- facial divisions, it is superficial to the external carotid artery and the temporo-maxillary vein. The nerve has been stretched close to its point of exit from the stylo-mastoid foramen for the relief of facial tic. It is best found at a spot about $ of an inch in front of the centre of the anterior vn] SECTION OF THE FACIAL NERVE 137 border of the mastoid process. It will be found above the posterior ^ belly of the digastric, which serves as a guide to it in the depth of the wound. Section of the facial nerve causes paralysis of the buccinator and of all the muscles of ex- pression, the mouth being pulled towards the sound side and the eye remaining unclosed. It also contains certain afferent fibres which are SUP TEMP.AR.T. AUDITOR/ /I EATUS *X ART S.TYLOI D PtlOC. TACIAL /leave S PI AIAL ACCESSORY /I. POCLOSSAL N. N SON'S DUCT CAKOTID Aar Fig. 35. Surface markings of the facial, spinal accessory, and hypoglossal nerves. A, Mid-point of anterior border of mastoid process ; B, point on anterior border of sterno-mastoid, 1 inch below mastoid process ; c, mid-point of posterior border of sterno-mastoid. Above B the transverse process of the atlas is indicated. sensitive to deep pressure. To restore mobility to the face in cases of palsy, surgeons have, in a number of instances, sutured the facial to the trunk of a neighbouring nerve the trunks selected being the spinal accessory and hypoglossal (Fig. 35). In tho one case the muscles of expression are thrown into action when the trapezius and sterno-mastoid are used; in the p* 138 THE HEAD AND NECK [CHAP. other when the tongue is moved. In course of time the patient may become able to dissociate these inconveniently combined movements. At its point of exit the facial nerve gives off its posterior auricular branch to the muscles of the ear and twigs to the posterior belly of the digastric and stylo-hyoid muscles. Tumours of the parotid are very apt to contain cartilaginous tissue. It is well known that, after mumps, metastatic abscesses are quite common in the testis. It is significant in this connexion that the testis is one of the few parts of the body, apart from bone, where cartilaginous matter forms a frequent constituent of the neoplasms of the part. Mr. Paget has pointed out that inflammation of the parotid is peculiarly frequent after injuries and diseases of the abdomen and pelvis. It occurs also very often as a sequela of some specific fevers, but more especially after typhoid. The anatomical or physiological basis of this connexion has not been made out. Many lymphatic glands are placed upon the surface and in the substance of the parotid gland. They receive lymph from the frontal and parietal regions of the scalp, from the orbit, the posterior part of the nasal fossae, the upper jaw, and the hinder and upper part of the pharynx. When enlarged, these glands may form one species of "parotid tumour." The parotid (Steiisoii's) duet (Fig. 35) is about 2^ inches long, and has a diameter of |- of an inch, its orifice being the narrowest part. At the an- terior border of the masseter muscle the duct bends suddenly inwards to pierce the buccinator muscle. The bend is so abrupt that the buccal segment of the duct may be almost at right angles with the masseteric. This bend should be taken into con- sideration in passing a probe along the duct from the mouth. The duct opens on the summit of a papilla placed on a level with the second upper molar tooth. The course of the duct across the masseter is represented by a line drawn from the vn] THE MAXILLA 139 lower margin of the concha to a point midway between the ala of the nose and the red margin of the lip. It lies about a finger-breadth below the zygoma, having the transverse facial artery above it and the infraorbital branches of the facial nerve below. The duct has been ruptured subcufcane- ously, leading to extravasations of saliva. Wounds of the duct are apt to lead to salivary fistulse. At least one-half of the buccal part of the duct is embedded in the substance of the buccinator muscle. A salivary fistula over the masseter may involve the parotid gland itself, or that part of it known as the socia parotidis. Inflammatory conditions may spread to the parotid from the mouth along the duct. 3. THE UPPER AND LOWER JAWS, AND PARTS CONNECTED WITH THEM Maxilla (for maxillary sinus, nee p. 119; for hard palate, see p. 162). This bone, on ac- count of its fragility and the manner in which it is hollowed out, is very readily fractured. As the bone is very vascular, serious injuries, involving great loss of substance, are often wonderfully repaired. Its hollowness, and the cavities that it helps to bound, render it pos- sible for large foreign bodies to be retained in the deeper parts of the face. Thus, Long- more reports "the case of Lieutenant Fretz, of the Ceylon Rifles, who was able to do his mili- tary duties for nearly eight years with the breech and screw of a burst musket lodged in the nares, part of the tail-pin and screw protruding through the hard palate into the^ mouth." The bone may undergo extensive necrosis, as in workers in match factories exposed to the fumes of white phos- phorus. In one case (.Medical Times and Gazette, 1862) of necrosis following measles the mischief was limited to the premaxillary, or incisive, bone. The periosteum of the maxilla is, like the pericranium, not disposed to form new bone. In HO THE HEAD AND NEGK [CHAP. ordinary cases of necrosis of the upper jaw no re- production of bone takes place, the gap being left permanent. In the mandible abundant new bone is produced by the periosteum, and extensive losses may be repaired. It is remarkable, however, that in course of years this new bone is liable to be very extensively reabsorbed. Excision of the maxilla, The entire bone has been frequently removed when the seat of an extensive tumour, and under certain other con- ditions. The bony connexions to be divided in the operation are the following (see Fig. 26, p. 107, and Fig. 30, p. 126) : (1) The connexion with the malar bone at the outer side of the orbit; (2) the connexion of the nasal (frontal) process with the frontal, nasal, and lacrimal bones; (3) the connexions of the orbital plate 'with the ethmoid and palate (the orbital plate is often left behind, or is cut through near the orbital margin) ; (4) the connexion with the opposite bone and the palate in the roof of the mouth; and (5) the connexion behind with the palate bone, and the fibrous attachments to the pterygoid processes. In the four first-named instances the separation is effected by^a cutting ^ instrument ; in the last- named, by simply twisting out the bone. Soft parts divided: These may be considered under three heads : The parts cut (1) in the first incision ; (2) in turning back the flap ; and (3) in separating the bone. (1) The following are the parts cut, in order from above downwards, in the usual, or "median," incision, an incision commencing parallel with the lower eyelid, and continued down the side of the nose, round the ala, and through the middle of the upper lip : Skin, superficial fascia, orbicularis oculi, palpebral branches of infraorbital nerve and artery, part of the levator labii superioris, angular artery and vein, lateral nasal artery and vein, nasal branches of infraorbital nerve, compressor naris (musculus nasalis), depressor of the septum and alse of the nose, attachment of nasal cartilage vii] THE MANDIBLE 141 to bone, orbicularis oris, superior coronary artery and vein, and mucous membrane of lip. Various branches of the facial nerve to the muscles may be cut. (2) In turning back the flap, the muscles above named will be dissected up, together with the internal palpebral ligament, if the frontal process is removed entire, the levator anguli, the buccinator, a few fibres of the masseter, and, on the orbital plate, the inferior oblique muscles. The infraorbital nerve and artery will be cut as they leave their foramen. In the flap itself will be the trunks of the facial artery and vein, the transverse facial artery, and the facial part of the facial nerve. (3) In separating the frontal process the lacrimal sac and infratrqchlear nerve will be damaged, and the naso-lacrimal duct and external branch of the nasal nerve cut across. In separating the bones below, the coverings of the hard palate are divided, and the attachment of the soft palate to the palate bone, unless the removal of that process can be avoided. " Any attempt to dissect off and preserve the soft covering of the hard palate is futile" (Heath). Posteriorly, the trunk of the infraorbital nerve is again divided (this time in front of the spheno-palatine ganglion), together with the posterior dental and infraorbital arte- ries, and some branches of the spheno-palatine artery. The deep facial vein from the pterygoid plexus will probably be cut, and, lastly, near the palate will also be divided the large palatine nerve and the descending palatine artery. It will be seen that no large artery is divided in the operation. The inferior turbinated bone (maxillo-turbinal) comes away, of course, with the maxilla. mandible. This bone is to a great extent protected from fracture by its horse-shoe shape, which gives it some of the properties of a spring, by its density of structure, by its^great mobility, and by the buffer-like inter articular cartilages that protect its attached extremities. The bone is usually broken by direct violence. 142 THE HEAD AND NECK [CHAP. and the fracture may be in any part. The sym- physis is rarely broken, on account of its great thickness. The ramus is protected by the muscu- lar pads that envelop its two sides, and the coro- noid process is still more out of the risk of injury, owing to the depth at which it is placed and the protection it derives from the zygoma. The weak- est part of the bone is in front, where its strength is diminished by the mental foramen and by the large socket required for the canine tooth. It is about this part, therefore, that fracture is the most common. The bone may be broken near, or even through, the symphysis by indirect violence, as by a blow or crushing force that tends to approximate the two rami. Thus, the jaw has been broken near the middle line by a blow in the masseteric region. The amount of displacement in fractures of this bone varies greatly, and is much influenced by the nature and direction of the force. In general terms, it may be said that when the body of the bone is broken the anterior fragment is drawn backwards and downwards by the jaw depressors, the digastric, mylo-hyoid, genio-hyoid, and genio- glossus; while the hinder fragment is drawn up by the elevators of the jaw, the masseter, internal pterygoid, and temporal. The dense muco-peri- osteum covering the alveolar part of the mandible is usually also torn through, and thus the frac- tured surfaces are exposed to the septic condi- tions which prevail within the mouth. It must be remembered that the mylo-hyoid muscle will be attached to both fragments, and will modify the amount of displacement. Fractures of the ramus are seldom attended with much displace- ment, muscular tissue being nearly equally attached to both fragments. In fractures of the body of the bone the dental nerve often marvellously escapes injury, a fact that is explained by the supposition that tue bones are not usually sufficiently displaced to tear across the nerve. Weeks after the accident, however, the nerve has become so compressed by the developing vii] MANDIBULAR JOINT 143 callus as to have its function destroyed. One or both condyloid processes have often been broken by falls or blows upon the chin. The mamlilMilai* (temporo-m axillary) joint is supported by a capsule which varies greatly in thickness in different parts. By far the thickest part of the capsule is the external part (the temporo-mandibular or lateral ligament). The internal part is next in thickness, while the anterior and posterior portions of the capsule are thin, especially the former, which is very thin. Thus, when this joint suppurates, the pus is least likely to escape on the external aspect of the articulation, and is most likely to find an exit through the anterior part of the capsule, although this part is to a great extent protected by the attachments of the external pterygoid muscle. Immediately behind the condyle of the jaw are the bony meatus and, a little to the inner side, the middle ear. In violent blows upon the front of the jaw these structures may be damaged, and it is interesting to note that the strongest ligament of the joint (the external lateral) has a direction downwards and backwards, so as im- mediately to resist any movement of the condyle towards the slender wall of bone that bounds the meatus and tympanum. Were it not for this liga- ment, a blow upon the chin would be a much more serious accident than it is. The- movements of this joint are peculiar. On opening the mouth it will be observed that the condyle moves forwards and downwards upon the articular eminence, while the angle of ^ the jaw moves in a backward and upward direction. The approximate axis of the movement is a transverse line drawn between the inferior dental fora- mina; thus, it will be seen that the inferior dental nerves (alveolar) enter the mandible at the point of least movement. The external pterygoid muscles, by pulling the condyle upon the articular eminence, take the chief part in opening the mouth; at the same time the chin is depressed by 144 THE HEAD AND NECK the contraction of the mylo-hyoid and digastric muscles. Dislocation. This joint permits of only one form of dislocation, a dislocation forwards. It may be unilateral or bilateral, the latter being the more usual, and it can only occur when the mouth hap- pens to be wide open. Indeed, the dislocation is nearly always due to spasmodic muscular action when the mouth is open, although in some few cases it has been brought about by indirect violence, as by a downward blow upon the lower front teeth, the mouth being widely opened. It has occurred during yawning, violent vomiting, etc. In more than one case the accident happened while a dentist was taking a cast of the mouth. Hamilton quotes a bilateral dislocation in a woman during the violent gesticulations incident to the pursuit of scolding her husband. When the mouth is widely opened, the condyles, together with the interarticular fibre-cartilage, glide forward. The fibro-cartilage extends as far as the anterior edge of the eminentia articularis, which is coated with cartilage to receive it. The condyle never reaches quite so far as the summit of that eminence. All parts of the capsule save the anterior are rendered tense. The coronoid process is much depressed. Now, if the external pterygoid muscle (the muscle mainly answerable for the luxation) contract vigor- ously, the condyle is soon drawn over the eminence into the zygpmatic fossa, the interarticular carti- lage remaining behind. On reaching its new posi- tion it is immediately drawn up by the temporal, internal pterygoid, and masseter muscles, and is thereby more or less fixed. A specimen in the Muse Dupuytren shows that the fixity of the lux- ated jaw may sometimes depend upon the catch- ing of the apex of the coronoid process against the malar bone. Subluxation of the mandible is a name given to a slight and quite incomplete dislocation of the jaw not infrequently met with in delicate women. It is due to a displacement of the interarticular vn] EXCISION OF THE MANDIBLE 145 cartilage, and can be cured by exposing the car- tilage and attaching it by suture to the fibrous structures around the joint (Annandale). Excision of the mandible. Considerable por- tions of the lower jaw can be excised through the mouth without external wound. In excising one entire half of the maxilla, a cut is made vertically through the lower lip down to the point of the chin, ana is then continued back along the inferior border of the jaw, so as to end near the lobule of the ear, after having been carried verti- cally upwards in the line of the posterior border of the ramus. The soft parts divided may be con- sidered under three heads : Those concerned (1) in the first incision ; (2) in clearing the outer surface of the bone; (3) in clearing the inner surface of the bone. 1. (a) In the anterior vertical cut: Skin, etc., orbicularis oris, inferior coronary and inferior labial vessels, branches of submental artery, leva- tor menti, mental vessels and nerve, some radicles of anterior jugular vein. (6) In the horizontal cut: Skin, etc., platysma, branches of superficial cervical nerve (nervus cutaneus colli) branches of supramandibular part of facial nerve, facial artery and vein at edge of masseter, and infra- mandibular branch of facial nerve (not neces- sarily divided), (c) The posterior vertical in- cision would not go down to the bone, and would merely expose the surface of the parotid gland and part of posterior border of masseter muscle. 2. In clearing the outer surface the ^ following parts are dissected back : Levator menti, the two depressor muscles, buccinator, masseter (crossed by part of parotid gland, transverse facial vessels, facial nerve, and Stenson's duct), masseteric ves- sels and nerve, temporal muscle. 3. In clearing the inner surface : Digastric, genio-hyoid, genio-glossus, and mylo-hyoid muscles, a few fibres of superior constrictor, internal pterygoid muscle, inferior dental (alveolar) artery and nerve, mylo-hyoid vessels and nerve, internal 146 THE HEAD AND NECK [CHAP. lateral ligament, rest of insertion of temporal muscle, mucous membrane. Parts in risk of being damaged. The facial nerve, if the posterior vertical incision be carried too high up. The internal maxillary artery, temporo-maxillary vein, auriculo-temporal nerve (structures all closely related to the jaw condyle), external carotid artery, lingual nerve, the paro- tid, submandibular, and sublingual glands. After subperiosteal resection the entire bone has been reproduced. Deformities. The lower jaw may be entirely absent, or of dwarfed dimensions, or incompletely formed. These conditions are congenital, and depend upon the defective development of the mandibular or first visceral arch, out of which the lower jaw is formed (Fig. 29, p. 124). They are often associated with branchial fistulse, super- numerary ears, macrostoma, and like congenital malformations. Nerves of the jaws. The upper teeth are sup- plied by the second division of the fifth, the lower by the third division. Some remarkable mani- festations of reflex action have followed irritative lesions of the dental nerves. Thus, cases of stra- bismus, temporary blindness, and wry-neck have been reported as due to the irritation of carious teeth. Hilton gives the case of a man who was much troubled by a carious tooth in the lower jaw (supplied by the third division of the fifth), and who developed a patch of grey hair over the region supplied by the auriculo-temporal nerve (a branch also of the third division). The roots of the third lower molar are in close proximity to the dental (mandibular) canal, and hence the nerve may be torn if this tooth is roughly extracted. The roots have been seen actually to enclose the nerve. Caries of the teeth is frequently associated with areas of hyperaesthesia on the side of the face and neck. The explanation of the reflection, to cer- tain areas of skin, of pain set up by dental caries must be sought for in a close association of the vii] MUSCLES OF MASTICATION 147 central nerve nuclei, in whrch the cutaneous and dental nerves terminate (see Fig, 33, p. 132). Disease of the peridental membrane does not give rise to referred pains (Head). The muscles of mastication are often at- tacked by spasm. Nowhere else in the body is a group of muscles opposed by so weak a group of opponents as in the mandibular region. The temporal, masseter, and internal pterygoid give the mandible its great biting and grinding power ; their opponents, which depress the mandible the external pterygoid, digastric, mylo-hyoid, genio- hyoid are able to afford but weak resistance to them. Hence, when in a state of spasm, they at once prevail over their opponents. When the spasm is clonic, chattering of the teeth is pro- duced. When the spasm is tonic the mouth is rigidly closed, and the condition known as trismus, or lockjaw, is produced. Trismus is among the first symptoms of tetanus. It is also very apt to be produced by irritation of any of the sensory branches of the third division of the fifth. Thus, trismus is very common in caries of the lower teeth, and during the "cutting" of the lower wisdom tooth; it is much less common in affec- tions of the upper set of teeth. If the motor root of the third division of the fifth nerve be cut in excising the Gasserian ganglion, paralysis and atrophy overtake the muscles of mastication of the corresponding side. The muscles of the sound side, however, are still able to carry on the necessary movements of the jaw concerned in speech and mastication. Teeth. As a test of age the following periods for the eruption of teeth are given by Mr. C, Tomes: Temporary teeth: Lower central incisors, six to nine months; upper incisors, ten months; lower lateral incisors and four first molars, a few months later ; then, after a rest of four or five months, the canines ; and, lastly, the second molars ; the whole being in place by the end of the second year. Permanent teeth: First molars, sixth 148 THE HEAD AND NECK [CHAP. or seventh year; next in order the lower central incisors, then the upper central incisors, and a little later the laterals, the eighth year ; first bicus- pids, ninth or tenth year; second bicuspids and canines, about the eleventh year, the lower preced- ing the upper; the second molars, the twelfth or thirteenth year; the wisdom teeth, 18 to 25 or later. An alveolar abscess is formed about the fang of a tooth. In the case of single-fanged teeth the pus may escape along the groove of the fang. CQRONOlD PffOC COMOVLE Fig. 36. A, Impaction of the upper third molar in the maxilla. B, Impaction of the lower third molar in the mandible. With other teeth the pus tends to pierce the alveolus. If the point of the fang is within the reflection of the mucous membrane from the gum to the cheek the abscess will break into the mouth, but if the point of the fang is without that reflec- tion, or if the pus can gravitate without the line of reflection, then the pus may break through the cheek. Alveolar abscess o>f the upper incisors and canines never breaks through the cheek. When connected with the upper molars it sometimes does; an abscess forming at the roots of the upper molar or second premolar teeth often breaks into the maxillary sinus. The roots of the incisor, VH] ALVEOLAR ABSCESS 149 canine, and first premolar teeth are more remote from the sinus; hence abscesses connected with them rarely break into the sinus. When con- nected with any of the lower teeth the abscess may find its way through the skin of the cheek. The upper wisdom tooth is developed in the posterior border of the upper jaw, and the- lower wisdom on the inner aspect of the ascending ramus. They may fail to come into position, or even remain deeply buried. (Fig. 36.) They may give rise to deeply seated and obscure abscesses which frequently point in the neck, at some distance from the site of origin. CHAPTER VIII THE MOUTH, TONGUE, PALATE, AND PHARYNX THE MOUTH The lips. The principal tissues composing the lips have the following relation to one another, proceeding from without inwards: (1) Skin; (2) superficial fascia; (3) orbicularis oris; (4) labial (coronary) vessels; (5) mucous glands, and (6) mucous membrane. The free border of the lip is very sensitive, many of the nerves having end-bulbs closely resembling tactile corpuscles. The upper lip is supplied with sensation by the second division of the fifth nerve, and the lower lip by the third division. Over these labial nerves a crop of herpes often appears (herpes labialis). The free border of the lower lip is more frequently the seat of epithelioma than is any other part of the body ; its lymphatic vessels pass to the submental and sub- mandibular lymphatic glands (Fig. 50, p. 207). The lips contain much connective tissue, and may swell considerably when inflamed, or cedematous. They are very mobile, and are entirely free for a considerable extent from bony attachment of any kind. It follows that destructive inflammations of the lips, and such losses of substance as accom- pany severe burns, produce much contraction and deformity of the ^ mouth. Contracting cicatrices, also, in the vicinity of the mouth are apt to drag upon the lips, everting them or producing kindred distortions. It is fortunate that the laxity of the tissues around the mouth, and the general vascu- 150 LIPS AND BUCCAL CAVITY 151 larity of the part, greatly favour the success of the many plastic operations performed to relieve these deformities. The lips are very vascular, and are often the seat of nsevi and other vascular tumours. The labial arteries are of large size, and their pulsa- tions can generally be felt when the lip is pinched up. These vessels run beneath the orbi- cularis oris muscle, and are consequently nearer to the mucous membrane than they are to the skin. When the inner surface of the lip is cut against the teeth, as the result of a blow, these arteries are very apt to be wounded. As such wounds are concealed from view, the consequent haemorrhage has sometimes given rise to an erroneous diag- nosis. Thus, Erichsen quotes the case of a drunken man, the subject of such a wound, who, having swallowed, and then vomited, the blood escaping from a labial artery, was for a while supposed to be suffering from an internal injury. As the anastomoses between the arteries of the lip are very free, it is usually necessary to tie both ends of the vessel when it has been cut across. The mucous glands in the submucous tissue are large and numerous. From closure of the ducts of these glands, and their subsequent distension, result the " mucous cysts " that are so common about the lips. " Hare-lip " is noticed below in connexion with the subject of cleft palate. Buccal cavity. The following points may be noticed in the examination of the interior of the mouth : In the floor of the mouth, on either side of the frenum linguae, can be observed the sub- lingual papillae with the openings of Wharton's ducts. The duct of Bartholin (one of the ducts of the sublingual gland) runs along the last part of the submandibular (Wharton's) duct, and opens either with it or very near it. This duct is singu- larly indistensible, and hence is partly explained the intense pain usually observed when it becomes obstructed by a calculus. The proximity of this duct to the lingual nerve may serve also to account 152 THE HEAD AND NECK [CHAP. for the pain in some cases. The submandibular gland can be made out through the mucous mem- brane at a point a little in front of the angle of the jaw, especially when the gland is pressed up from the outside. On the floor of the mouth, between the alveolus and the anterior part of the tongue, is a well-marked ridge of mucous mem- brane, directed obliquely forwards and inwards to the sublingual papilla near the frenum. It indi- cates the position of the sublingual gland (Fig. 37), and also, so far as it goes, the line of the submandibular duct and the lingual nerve. These Cenio /wo GLOSS CEAIIO-rtYOlO Su> UAGU*ll I/HM.IHCUALI& /IYO-CLOSMJS LlCUALApTEBV SuBUNCUftl Ci- Fig. 37. Section across tongue and mandible to show the position of the sublingual gland and lingual artery. (After Poiricr.) structures, with the sublingual artery, lie beneath the mucous~membrane between the gland and the side of the tongue. The ducts of the sublingual gland, some ten to twenty in number, open into the mouth along the ridge of mucous membrane just referred to. Ranula, a cystic tumour filled with mucous contents, is often met with over the site of the sublingual gland, and is due to the dilatation of a duct which has become ob- structed, or to an occluded mucous follicle. The mucous membrane of the floor of the mouth, as it passes forwards to bo reflected on to the gums, is attached near to the upper border of the jaw (Fig. 37). Here also are situated some mucous glands vm] THE MOUTH 153 which may become cystic. The genio-glossus is attached near the lower border. Between these two parts (the mucous membrane and the muscle) there is, according to Tillaux, a small space lined with squamous epithelium. To this cavity the name of the sub-lingual bursa is given. It is constricted is its centre by the frenum linguae, and is said to be the seat of mischief in "acute ranula." When the mouth is widely opened the pterygo- mandibular ligament can be readily seen and felt beneath the mucous membrane. It appears as a pro- minent fold running obliquely downwards behind the last molar teeth. A little below' and in front of the attachment of this ligament to the lower jaw, the lingual nerve can be felt as it lies close to ^ the bone just below the last molar. At this point it may be divided, or reached by the needle of a syringe. This nerve, as it lies against the bone, has been crushed by the slipping of the forceps in clumsy extraction of the lower molar teeth. The coronoid process of the lower jaw can be easily felt through the mouth, and is especially distinct when that bone is dislocated. It may be noted that a fair space may exist between the last molar tooth and the ramus of the mandible, through which a patient may be fed by a tube in cases of trismus or ankylosis of the jaw. Congenital dermoid and thyroid cysts are some- times found in the floor of the mouth between the tongue and the lower jaw. Such cysts are supposed to be due to imperfect closure of the first visceral or postmandibular cleft, or to an aberrant bud of the median thyroid outgrowth. The gums are dense, firm, and very vascular. In the bleeding that follows the extraction of teeth much of the blood is supplied by them. The gums are particularly affected in mercurial poison- ing, and are also especially involved in scurvy. In chronic lead-poisoning a blue line often appears along their margins. This is due to a deposit of 154 THE HEAD AND NEGK [CHAP. lead sulphide in the gum tissues, which is thus derived : Food debris collected about the teeth in decomposing produces hydrogen sulphide, which, acting upon the lead circulating in the blood, pro- duces the deposit. The blue line, therefore, is said not to occur in those who keep the teeth clean. THE TONGUE On the under surface of the tongue, less than an inch from the frenum, the end of the ranine (comitans hypoglossi) vein can be seen beneath the mucous membrane. Two elevated and fringed lines of mucous membrane may be seen on the under surface of the organ, converging towards its tip. They indicate the position of the ranine (deep lingual) artery, which is more deeply placed than the vein, close to which it lies. It is extremely rare for the tongue to be the seat of congenital defects. The tip may be irregularly cleft or show glandular polypi, probably derived from the glands normally found beneath the tip of the tongue. Fournier gives a case where the tongue was so much longer than usual that the chest could be touched with its tip while the head was held erect. In rare cases the fremini linguae may be abnormally short, constituting the condition known as " tongue-tie," which is really a very uncommon affection. The genio-glossus, the chief muscle of the f tongue, and the genio-hyoid arise from the genial (mental) tubercles of the symphysis. The tongue is kept from falling backwards by its attachments to the symphysis; if these attach- ments were cut, the tongue could be inverted and swallowed. In complete anaesthesia, as in that produced by chloroform, when all the muscular attachments of the tongue are relaxed, the organ is apt to fall back and to press down the epiglottis, so causing suffocation. The tongue is firm and dense, but contains, nevertheless, a sufficient amount of connective tissue to cause it to swell greatly when inflamed. vm] LINGUAL VESSELS AND NERVES 155 The surface epithelium is thick, and in chronic superficial inflammation of the organ it often be- comes heaped up, forming dense opaque layers ichthyosis linguae, plaques des fumeurs, leucoma, etc. From the mucous glands, situated chiefly be- neath the mucous membrane near the base of the tongue, the mucous cysts are developed that are sometimes met with in this part. The tongue is very vascular, and is in conse- quence often the seat of nsevoid growths. Its main supply is from the lingual artery* This vessel approaches the organ from the under surface, and, as cancer usually shows a tendency to spread towards the best blood supply, it is to be noticed that carcinoma of the tongue nearly always tends to spread towards the deep attachment of the member. At the same time it must be observed that the main lymphatics follow the same course as the main blood-vessels; cancer in spreading tends also to follow the lymph-stream. The vascularity of the tongue is the great bar to its easy removal, haemorrhage being the complication most to be dreaded in such operations. The toiigiie is well supplied with nerves. which endue it not only with the special sense of taste, but also with common sensation. According to Weber's experiments, tactile sensibility is more acute on the tip of the tongue than it is on any part of the surface of the body. It should be borne in mind that the lingual nerve, in ^ which the chorda tympani is incorporated, supplies the fore part and sides of the tongue for two-thirds of its surface, while the glosso-pharyngeal nerve supplies the mucous membrane at its base, and especially the papillae vallatse. After excision of the semilunar ganglion, taste is unaffected because the fibres subserving that sense reach the lingual nerve in the chorda tympani. The latter nerve must also convey touch fibres, for after excision of the semdlunar ganglion a certain sensibility to touch is still retained by the anterior two-thirds of ihe tongue, although sensibility to pain is 156 THE HEAD AND NEOK [CHAP. completely lost. In painful affections, situated in the area supplied by the lingual nerve, the patient is often troubled with severe pains deep in the region of the meatus of the ear, and an area of skin from the ear along the lower border of the jaw may be tender (Head). The anterior two-thirds of the tongue are a derivative of the mandibular arch, which also forms the anterior DORSAL PLEXUS UP. DEEP CERV. GLANDS SUBLINQ. GLAND SUBMENTAL MYLO-HYOID SUBMAX. CAROTID ART. Fig. 38. Lymphatics of the tongue. (After Poirier.) boundary of the meatus. Hence the nerve supply of the anterior part of the tongue from the third divi- sion of the fifth nerve and the reference of pain to its cutaneous termination. The posterior third of the tongue is derived from the second (hyoid) and third visceral arches and is associated with tender areas in the skin over the larynx (Head). Spas- modic contraction of the masticatory muscles is sometimes found to accompany painful lingual ul- cers when involving the region of the gustatory VIH] LINGUAL LYMPHATICS 157 nerve. There would seem to be little connexion between an abscess over the occipital region and wasting of one half of the tongue. But Sir James Paget reports the following case : "A man received an injury to the back of his head that was apparently not severe. In time the right half of the tongue began to waste, and continued to waste until it was less than half the size of the unaltered side. An abscess formed over the occiput, from which fragments of the lower part of the occipital bone were removed. After the removal of all the dead bone the tongue began to recover, and in one month had nearly regained its normal aspect." Here the atrophy was due to wasting of the lin- gual muscles produced by pressure upon the hypo- glossal nerve, which leaves the skull through the anterior condyloid foramen in the occipital bone. The case illustrates the importance of remember- ing even small foramina, and the structures they transmit. The tongue contains much lymphoid tissue, a considerable part of which (the lingual tonsil) is massed under the mucous membrane at the pos- terior part of the organ. Hypertrophy of this tissue may lead to troublesome symptoms by irritating the sensitive epiglottis. The lingual and pharyn- geal adenoid tissue, and the tonsils proper, form a complete ring of lymphoid tissue round the isthmus of the fauces. The lingual lymphatics (Fig. 34) are large and numerous, and offer a free channel for the dissem- ination of cancerous emboli. They are arranged in two systems : (1) Superficial, forming an ex- tremely rich plexus in the submucous tissue on the dorsum and sides of the tongue; (2) deep, arranged as a network in the musculature of the tongue. These two systems are in free com- munication; Cheatle found that the genio-glossus muscle was a common site of secondary deposit in cases of cancer of the tongue. The lymph from these two systems is carried off by the following sets of efferent vessels: (1) the marginal or lateral 158 THE HEAD AND NECK [CHAP. vessels, which leave the submucous plexus on the side of the tongue and pass partly to the sub- mandibular group of glands and partly to the upper deep cervical group ; (2) the central vessels, which form between the two genio-glossus muscles and end in the upper deep cervical glands; (3) the apical vessels, which end in the submental gland and in the upper deep cervical ; (4) the basal vessels frona the posterior third of the tongue which terminate in the upper deep cervical group.* The main vessels become blocked by the invasion of cancer cells, so that the lymph has to seek by-paths and circuitous routes, which also in time become occluded. Thus the cancerous invasion may become widely spread and in many directions. The lymphatic glands over the sub- mandibular gland, the lymphoid tissue in that gland and in the sublingual, become the seats of secondary deposit. The submental gland may also be affected. In the strange congenital affection known as macroglossia the tongue becomes much enlarged, and in some cases may attain ^prodigious dimen- sions. The enlargement is primarily due to the greatly dilated condition of the lymphatic chan- nels of the organ (hence the name, lymphangioma cavernosum, proposed by Virchow), and to an in- creased development of lymph tissue throughout the part. The portion most conspicuously affected is the base of the tongue, where the lymphatics are usually the most numerous. Accessory glands about the tongue. Accessory glands, belonging to the thyroid body, are frequently found in the vicinity of the hyoid bone. They are also found in the basal part of the tongue, near the foramen caecum (Makins). Some may be superficial to the mylo- hyoid muscle, others may be just above the hyoid bone, and others in the hollow of that bone. Cysts lined with ciliated epithelium may ' * For a full account of the lymphatics see Poirier's "Lymphatics, translated by Cecil Leaf, 1903. vni] EXCISION OF THE TONGUE 159 sometimes be found in the same situations. All these structures are the remains of the neck of the central diverticulum which is pro- truded from the ventral wall of the pharynx in the embryo, and from which the isthmus and adjoining part of the thyroid gland are formed. The foramen ccecum on the tongue indicates the spot where this diverticulum arises from the pharynx. Ducts lined with epithelium have been found leading from the foramen caecum to accessory glands about the hyoid bone. From these glandular and epithelial collections about the hyoid bone certain deep-seated forms of cancer of the neck may be developed. Some of these take the form of malignant cysts described by the author (Path. Soc. Trans., 1886). Excision. Many different methods have been adopted for the removal of the entire tongue. It has been removed through the mouth by the ecra- seur or the scissors, the latter operation being per- formed with or without previous ligature of the lingual arteries in the neck. It is difficult, however, fully to expose the deeper attachments of the organ through the comparatively small orifice of the mouth. To obtain more room the cheek has been slit up in one procedure, while the lower lip and symphysis of the lower jaw have been divided in another. In another series of operations the tongue has been reached, or the organ has been fully exposed, by an incision made between the hyoid bone and the mandible. Kocher introduced the method of exposing the tongue from the neck, reaching it by an incision commencing near the ear and fol- lowing the anterior border of the sterno-mastoid muscle as far as the hyoid bone, whence it turns upwards along the anterior belly of the digastric muscle. This method, besides giving an 'oppor- tunity of completely controlling haemorrhage by a preliminary ligature of the lingual artery, allows free removal of the upper deep cervical glands, the lymphatic glands, and the tissue over and in the 100 THE HEAD AND NECK [CHAP. submandibular and sublingual glands which form the seats of secondary cancerous deposits. In the removal of the entire organ, the following parts are of necessity divided : The frenum, the mucous membrane along the sides of the tongue, the glosso-epiglottic folds, the genio- glossus, hyo-glossus, stylo-glossus. palato-glossus muscles, the few fibres of the superior and inferior lingual muscles which are attached to the hyoid bone, the terminal branches of the lingual, glosso- pharyngeal, and hypoglossal nerves, the lingual vessels, and, at the side of the tongue near its base, some branches of the ascending pharyngeal artery and of the tonsillar branch of the facial artery. THE PALATE The arch of the hard palate varies in height and shape in different individuals; it is particu- larly narrow and high in those who have suffered in youth from adenoids. The outline of this arch is of some moment in operations upon the palate. Cleft palate. In order to understand the various forms of cleft which occur in the palate and upper lip, it is necessary to review briefly the development of these parts; for all forms of cleft palate and "hare-lip" are due to an incomplete fusion of parts. In Fig. 39, A, the bony palate at birth is shown to be made up of three elements : (1) the premaxillary (os incisivum), carrying the four incisor teeth ; (2) the right maxillary; (3) the left maxillary, bear- ing the right and left canines and^milk molars. These three parts are different in origin : the pre- maxillary part is developed in the mesial nasal process (Fig. 29, p. 124) ; the maxillary parts from the right and left maxillary processes. Fusion of the various elements to form the palate com- mences anteriorly and proceeds backwards. In the posterior two-thirds of the palate the maxillary processes fuse with each other in the median line, viii] DEVELOPMENT OF BONY PALATE 161 but in the anterior third they unite with the premaxillary part. Thus the line of fusion is Y-shaped, the premaxillary part occupying the fork. In the majority of cases the cleft occurs in the position of the main stem of the Y, or it may .affect only the soft palate; or it may extend forwards to the alveolus on one side or on both, as is shown in Fig. 39, B, c. The lateral incisor is developed in the groove between the premaxillary and maxillary elements; if the condition of cleft Fig. 39. Illustrating the relationship of the lateral incisor tooth to the palatal cleft. A, Normal hard palate. The premaxilla is stippled ; the lateral incisor occurs in the suture between it and the maxilla. B, Double cleft palate, the lateral incisor being situated on the premaxilla to the inner side of the cleft. The septum of the nose is exposed in the cleft between the maxillary bones. c, Double cleft palate, the lateral incisor being situated on the maxilla to the outer side of the cleft. palate occurs, the developmental elements separate as growth proceeds; the bud of the lateral incisor may adhere to either side of the cleft thus formed ; hence in some cases this incisor is found on the premaxillary process ; In others, in the maxillary (Fig. 39, B, c). Each premaxilla may show two centres of ossification, but the cleft is not, as is so often said, the result of the failure of union of two centres of ossification, but is due to the separation of the developmental parts of the palate. ' As growth goes on during childhood the cleft becomes wider. The upper lip is developed from the same three 162 THE HEAD AND NEGK [CHAP. elements as the palate (Fig. 29, p. 124) ; if the palatal cleft extends to the alveolus the lip is also affected, but a cleft on one or both sides of the lip may occur without a cleft of the palate. The premaxillary or median element of the lip is also bilateral in origin, but it is extremely rare to find a persistent separation of its two parts. In cases of double hare-lip one sees occasionally two papillae on the lower lip, fitting into the clefts in the upper when the lips are in apposition. The mucous membrane covering the hard palate is peculiar in that it is practically one with the periosteum covering the bones; and, therefore, in dissecting up this membrane the bone is bared, as the mucous membrane and the perios- teum cannot be separated. The membrane is thin in the middle line, but is much thicker at the sides near the alveoli, the increased thickness depend- ing mainly upon the introduction of a number of mucous glands beneath the surface layers, such glands being absent in the middle line. The density and toughness of the soft covering of the hard palate render it very easy to manipulate when dissected up in the form of flaps, as in the operation for cleft palate. Sir Rickman Godlee has described a number of cases in which a bony elevation the torus palatinus is found on the posterior part of the under surface of the hard palate. The elevation or exostosis is commoner in lower races than in Europeans, and begins to form as adult life is reached. It is due to a heaping-up of bone on each side of the median suture of the palate, and in exceptional cases attains noticeable dimensions. The main blood supply of the bones of the hard palate and of its mucous covering is derived from the descending palatine branch of the in- ternal maxillary artery. This vessel, which is practically the only vessel of the hard palate, emerges from the posterior palatine canal near the junction of the hard palate with the soft, and vni J THE SOFT PALATE 163 close to the inner side of the last molar tooth. The vessel runs forwards and inwards to end at the anterior palatine canal. Its pulsations on the palate can often be distinctly felt. In dis- secting up muco-periosteal flaps from the hard palate by means of a raspatory, it is most important to make the initial incision in the mucous membrane close to the alveolus, so that the flap may include this artery, and its vitality thereby be secured. In dissecting up the flap it should be remembered that the artery runs much nearer to the bone than to the mucous surface. The soft palate is of uniform thickness, its average measurement being estimated at about 5 of an inch. Its thickness is largely due to a stratum of mucous glands on its upper sur- face. Its central basis is a tendinous expansion, the palatal aponeurosis, in which the tensors of the palate end and by which they are at- tached to the posterior border of the hard palate. When the soft palate is congenitally cleft, the edges of the fissure are approximated dur- ing swallowing by the uppermost fibres of the superior constrictor. This approximation may narrow the cleft by one-half or two-thirds. The muscles that tend to widen the cleft are, in the main, the levator palati and tensor palati. It is necessary that these muscles should be divided in attempting to close the cleft by operation. The levator palati crosses ^ the palate obliquely from above downwards and inwards on its way to the middle line, lying nearer to the upper than the lower surface of the velum. The tensor palati turns round the hamular process, and passes to the middle line in a nearly hori- zontal direction (Fig. 40). The hamular process can be felt through the soft palate just behind and to the inner side of the last upper molar tooth. When the muco-pcriosteum, containing the posterior palatine vessels, has been raised from the hard palate on each side of the cleft, so that the hinder border of the horizontal plate of the 164 THE HEAD AND NEGK [CHAP. palate bone is exposed, the operator separates the palatal aponeurosis and the overlying mucous membrane on the nasal aspect from the palate bone, taking care to stop short of the posterior palatine canal and palatine vessels. When the aponeurosis is cut through the tensor palati is partly thrown out of action. The levator palati EUSTACH.TUBl. LEV. PALATI Fig. 40. Muscles of the soft palate, from behind. (Blake w ay .} is best cut as it enters the upper surface of the soft palate within a raised fold of mucous membrane. Its nerve enters the upper end of the muscle, and is thus left undamaged (Berry and Legg). The blood supply of the soft palate is derived from the descending palatine branch of the in- ternal maxillary artery, the ascending pharyn- vm] THE PHARYNX 165 geal artery, and the ascending palatine branch of the facial artery. The latter vessel reaches the velum by following the levator palati muscle, and must be divided in the section made of this muscle in the procedure just described. The muscles of the soft palate are supplied by several nerves. The levator palati, azygos uvulae, and palato-pharyngeus are innervated with the muscles of the pharynx by the spinal accessory; the palato-glossus with the muscles of the tongue from the hypoglossal, and the tensor palati with the tensor tympani from the third division of the fifth nerve through the otic ganglion. THE PHARYNX The pharynx is about 5 inches in length. It is much wider from side to side than from before backwards. It is widest at the level of the tip of the greater cornua of the hyoid bone, where it measures about 2 inches. It is narrowest where it joins the gullet opposite the cricoid cartilage, its diameter here being less than f of an inch. The pharynx is not so Targe a space as supposed, for it must be remembered that during life it is viewed very obliquely, and erroneous notions are thus formed of its antero- posterior, dimensions. The distance from the arch of the teeth to tho commencement of the gullet is about 6 to 7 inches, a measurement that should be borne in mind in extracting foreign bodies. Foreign bodies passed into the pharynx are most apt to lodge at the level of the cricoid cartilage, a point that, in the adult, is a little beyond the reach of the finger. The history of foreign bodies in the pharynx shows that that cavity is very dilatable, and can accommodate for some time large sub- stances. Thus, in a case reported by Dr. Geoghe- gan, a man of 60, who for months had had some trouble in his throat for which he could not account, was supposed to have cancer. On ex- amination, however, a plate carrying five false teeth, and presenting niches for five natural ones, J66 THE HEAD AND NECK [CHAP. was found embedded in the pharynx, where it had been lodged for five months. The plate had been swallowed during sleep (Med. l j rtss, 1866). In the Lancet for 1868 is an account of a mutton chop that became lodged in the pharynx of a gluttonous individual. The chop presented the ordinary vertebral segment of bone, together with l\ inches of rib, and was " pretty well covered with meat." Attempts to remove it failed, and it was finally vomited up. Dr. Hicks (Lancet, 1884) reports the case of a woman who committed suicide by cramming half a square yard of coarse calico (belonging to her nightdress) into her mouth and throat. The walls of the pharynx are in relation with the base of the skull, and with the upper six cer- vical vertebrae. The arch of the atlas is almost exactly on a line with the hard palate. The axis is on a line with the free edge of the upper teeth. The termination of the pharynx corresponds to the sixth cervical vertebra. The upper vertebrae can be examined, as regards their anterior sur- face, from the mouth. When the bones about the pharynx are diseased, the necrosed parts may be discharged by that cavity. Thus portions of the atlas and axis have been expelled by the mouth, as also have been some fragments of comparatively large size thrown off by the occipital and sphenoid bones. The mucous membrane of the pharynx is vas- cular, and readily inflamed; and such inflamma- tions are peculiarly dangerous, in that they may spread to the lining membrane of the larynx. The submucous tissue of the aryteno-epiglottic folds and of the neighbouring part of the pharynx is peculiarly loose, and in oBdematous conditions the upper aperture of the larynx may be almost closed. Much adenoid tissue is distributed in the mucous membrane of the pharynx, and it is this tissue that is the primary seat of inflammation in various forms of pharyngitis. A distinct col- mi] POSTNASAL GROWTHS 167 lection of adenoid tissue the pharyngeal tonsil is found in the roof of the naso-pharynx (see Figs. 41 and 27). It is embedded in thick mucous membrane, and extends from the base of the septum of the nose to the mid-point of the basilar process of the skull. The centre of the ton- sil is marked by a fissure or depression bounded on each side by two or three folds of mucous membrane laden with adenoid tissue. It reaches its maximum size about the tenth year. ^ It ex- tends laterally towards the recesses behind the Eustachian tubes, and may invade these recesses and - /mmf&i %^ar ROOF OF thus prevent the ^^^^^^^^ NASO-PHARYNX free opening of the tubes This deposit mm ^^ mm of adenoid tissue Wem&&iiL ^m EUSTACH. T L the condition known as " adenoid Vege- POST. BORDER OF tations " or " post- SEPTUM NAS1 nasal growths" be Fig. 41. Tonsil of the naso-pharynx produced. These of a boy aged 2 years, growths may cause (From a preparation made by Prof . deafness and may Symington.) block the posterior nares. They need to be removed by operation. They are supplied by minute arteries derived from the internal maxillary (Vidian and pterygo- palatine) and from the ascending pharyngeal. The veins join the pharyngeal plexus, and the lymphatics drain to the retropharyngeal gland, thence to the deep cervical glands. The tissue immediately outside the pharyngeal walls is lax, and favours the spread of effusion. Thus, in acute inflammation of the pharynx the effusion has been found to extend along the esophagus, reaching the posterior mediastinum, and advancing even to the diaphragm. In the lax connective tissue between the pharynx and the 168 THE HEAD AND NECK [CHAP. spine abscess is not infrequent, due, as a rule, to caries of the vertebrae (postpharyngeal abscess). In this connective tissue, and opposite the axis, is also found a lymphatic gland that receives lymphatics from the nasal cavity and naso- pharynx. This gland may prove the seat of a suppuration. Such collections may so push for- ward the posterior pharyngeal wall as to depress the soft palate, or may cause severe dyspnoea by interference with the larynx. The matter may discharge itself through the mouth, or may reach the neck by passing behind the great vessels and the parotid gland, presenting ultimately beneath or at one border of the sterno-mastoid muscle. Many structures of importance are in relation with the lateral, walls of the pharynx, the prin- cipal being the internal carotid artery, the vagus, glosso-pharyngeal, and hypoglossal nerves (Fig. 34, p. 134). The internal carotid is so close to the pharynx that its pulsations may be felt by the finger introduced through the mouth. These and other deep structures in the neck may be wounded by foreign bodies that, passing in at the mouth, have been thrust through the pharynx into the cervical tissues. The internal jugular vein is at some distance from the pharynx, espe- cially at its upper part (Fig. 34, p. 134). The styloid process, when prominent, and an ossified stylo-hyoid ligament, can also be felt at the side of the pharynx immediately behind the tonsil. In more than one case an ossified stylo-hyoid ligament has been mistaken for a foreign body, and an attempt made to excise it. The tonsil (Figs. 42, 43) is lodged between the anterior and posterior palatine arches. It is in relation externally with the superior constrictor muscle (Fig. 34, p. 134), and it corresponds, as regards the surface, to the angle of the lower jaw. When hyper trophied, the mass tends to develop towards the middle line, where no resistance is encountered, and to effect but little change in its external relations. The mass, often mistaken vin] THE TONSIL 169 for the enlarged tonsil in the neck, is formed of enlarged glands, situate near the tip of the great cornu of the hj^id bone, and overlying the internal jugular vein. These glands receive the tonsillar lymphatics, and are almost invari- ably enlarged in all tonsil affections. The fact that these glands are so frequently the first to en- large when the cervical glands become tuberculous points to the tonsil as a common site of primary infection. The tonsil is closely enough attached to SOFT PALATE PLICA SEMILUNARI TONGUE EPIGLOTTIS Fig. 42. Diagram of the pillars of the fauces and of the tonsil. the pharyngeal wall to be affected by the movements of the pharyngeal muscles (Fig. 43). Thus it is moved inwards by the superior constrictor muscle during the act of swallowing, and may be drawn outwards, on the other hand, by the stylo-pharyn- geus muscle. The ease with which a tonsil can be reached depends, other things being equal, upon the extent to which it can be withdrawn by the stylo-pharyngeus, and upon the development of the anterior palatine arch, which, to some extent, hides the tonsil. A child with a prominent an- terior palatine arch, containing a well-developed 170 THE HEAD AND NECK [CHAP. palato-glossus muscle, and with a vigorous stylo- pharyngeus, can for a long time elude the tonsil guillotine. Nevertheless the tonsil can be re- moved intact and with its capsule still adherent to it. The extent to which a tonsil projects beyond the level of the pillars is no index to its real size (Pybus). The tonsil is variable in shape ; it is frequently divided into three masses, and, besides numerous SUP. CONSTRICTOR STYLO~PHARYNQE:US STYLO-GLOSSUS TONSIL ANTER. PILLAR PAL ATO -GLOSS MANOIB. NERVE. CONSTRIC'TOA Sr* MOLAR BUCCINATOR Fig. 43. Horizontal section across the tonsil and its capsule, and the pillars of the fauces. crypts, shows towards its upper part, where the anterior and posterior pillars meet with the soft palate, a deep recess or pocket the tonsillar recess. This recess is the remnant of the first visceral cleft in which the tonsil was developed (Seccombe Hett). From the anterior pillar a sharp fold of mucous membrane passes back- wards, to end on the tonsil the plica triangularis (Fig. 42) while another fold may join the pil- lars over the tonsillar racess (plica semilunaris}. vin] HYPERTROPHIED TONSIL 171 The tonsil is separated from the superior con- strictor by a fine fibrous capsule (Fig. 43) ; its lymphatics perforate the constrictor. Two chief forms of tonsil may be recognized : the embedded, where the adenoid tissue increases beneath the level of the pillars ; and the projecting^ where the increase affects chiefly the exposed part of the tonsil (S. Hett). Deafness is often complained of when the tonsil is hypertrophied. This is not due to closure of the Eustachian tube by the direct pressure of the enlarged mass; such pressure is anatomically impossible. The large tonsil may, however, affect the patency of the tube, by disturbing the soft palate, and through it the tensor palati muscle, which is much concerned in keeping open the Eustachian tube. The deafness in these cases is probably due rather to an extension of the hyper- trophic process to the lining membrane of the tube than to any pressure effects, since it is usually not improved until some time after the tonsil has been removed. The tonsillar tissue is for the most part collected around a number of crypts (Fig. 43). The decomposition of retained epithelial structures within these recesses pro- duces the fetid breath often noticed in cases of enlarged tonsil, and probably incites the attacks of inflammation to which such tonsils are liable. Calculi may form in these crypts and give rise to a spasmodic cough. In this case the glosso- pharyngeal nerve conveys the afferent impulse to the respiratory centre. The tonsil is very vascular, receiving blood from the tonsillar and palatine branches of the facial artery, from the descending palatine branch of the internal maxillary, from the dorsalis lin- guae of the lingual, and from the ascending pharyngeal. Hence the operation of removing the tonsil is often associated with free bleeding. The internal carotid artery is close to the pharynx, but some way behind the gland (Fig. 34, p. 134). The vessel is, indeed, about \ of an inch 172 THE HEAD AND NECK posterior to that body, and is in comparatively little danger of being wounded when the tonsil is excised. The internal jugular vein is a con- siderable distance from the tonsil. The facial artery, in its cervical stage, is close to the tonsil. Of important cervical structures, the nearest to the tonsil is the glosso-pharyngeal nerve. The ascending pharyngeal artery is also in close re- lation with it. Although this vessel is of small size, bleeding from it has proved fatal, as the following interesting case, reported by Mr. Mor- rant Baker, will show : A man aged 23 fell when drunk, and grazed his throat with the end of a tobacco-pipe he was smoking 1 at the time. He thought nothing- of the accident. In two days he came to the hospital with what appeared to be an acutely inflamed tonsil. The tonsil was punctured, but nothing escaped save a little blood. Several haemorrhages occurred from the tonsil wound, and on the fourth day after the accident 1 inch of the stem of a clay pipe was discovered deeply embedded in the glandular substance. It was removed, and the common carotid tied. The patient, however, never rallied from the previous severe haemorrhages, and soon died. The autopsy showed that the stem of the pipe, which had not been missed by the patient, had divided the ascending pharyngeal artery. (SH, Hart:* Hosp. Report*, 1870.) The tonsil is often the seat of malignant growths. Such tumours have been removed through the mouth, but are more conveniently dealt with through an incision in the neck along the anterior edge of the sterno-mastoid (Cheevers' operation). CHAPTER IX THE NECK Surface anatomy; bony points. The by old bone is on a level with the fourth cervical vertebra, while the cricoid cartilage is opposite the sixth. The upper margin of the sternum is on a level with the disc between the second and third dorsal vertebrae. (See p. 187.) At the back of the neck there is a slight depression in the middle line which descends from the occipital protuber- ance, and lies between the prominences formed by the trapezius and complexus muscles of the two sides. At the upper part of this depression the spine of the axis can be made out on deep pres- sure. Below this, the bony ridge formed by the spines of the third, fourth, fifth, and sixth cervi- cal vertebrae can be felt, but the individual spines cannot usually be distinguished. At the root of the neck the spinous process of the vertebra prominens is generally very obvious. The trans- verse process of the atlas may be felt just below and in front of the tip of the mastoid process. By deep pressure in the upper part of the supra- clavicular fossa, the transverse process of the seventh cervical vertebra can be distinguished. If pressure be made over the line of the carotid vessels at the level of the cricoid cartilage, the prominent anterior tubercle of the trans- verse process of the sixth cervical vertebra can be felt. This is known as the "carotid tuber- cle." The carotid artery lies directly over it, and in ligaturing that vessel some surgeons make important use of this tubercle as a landmark. If a horizontal section of the neck, in a muscular v 173 174 THE HEAD AND NECK [CHAP. subject, taken about the level of the sixth cervical vertebra, be viewed, the whole of the body of the vertebra divided will be seen to lie within the anterior half of the section. Middle Iiiie.-In the receding angle below the chin the hyoid bone can be felt and its body and greater cornua well made put. About a finger's-breadth below it is the thyroid cartilage. The details of this latter are readily distin- guished, and below it the cricoid cartilage, crico- thyroid space, and trachea can be easily recog- nized. The separate rings of the trachea cannot be felt. The trachea is less easily made out as it passes down the neck As it descends it takes a deeper position, and at the upper border of the sternum lies nearly 1^ inches from the surface. The rima glottidis corresponds to the middle of the anterior margin of the thyroid cartilage. Unless enlarged, the thyroid gland cannot be made out with certainty. According to Holden, the pulse of the superior thyroid artery can be felt at its upper and anterior part. The anterior jugular veins descend on either side of the middle line upon the sterno-hyoid mus- cles. They commence in the submandibular region, pierce the fascia just above the inner end of the clavicle, and, passing beneath the origin of the sterno-mastoid muscle, end in the external jugu- lar. The inferior thyroid veins lie in front of the trachea, below the isthmus. Side of the neck. Muscles. The sterno- mastoid muscle, especially in thin subjects and when thrown into action, is a prominent feature in the neck. The anterior border of the muscle is very distinct. The posterior border is less promi- nent, especially at its upper part. A communi- cating branch from the facial vein generally runs along the anterior border of the muscle to meet the anterior jugular vein at the lower part, of the neck. The interval between the sternal and clavicular parts of the muscle is generally well marked. If a needle be thrust through this in- ix] VESSELS OF THE NEGK 175 terval, quite close to the clavicle, it would just touch the bifurcation of the innominate artery on the right side and would pierce the carotid vessel on the left. The posterior belly of the digastric muscle corresponds to a line drawn from the mastoid process to the anterior part of the hyoid bone. The anterior belly of the omo-hyoid follows an oblique line drawn downwards from the fore part of the hyoid bone, so as to cross the line of the carotid artery opposite the cricoid cartilage. The posterior belly can be made out in thin necks, especially when in action, running nearly parallel with and just above the clavicle. Although not taking quite the same direction, yet the posterior borders of the sterno-mastoid and anterior scalene muscles practically correspond to one another. Vessels. The common carotid artery is repre- sented by a line drawn from the sterno-clavicular joint to a point midway between the angle of the mandible and the mastoid process. The vessel bifurcates at the upper border of the thyroid car- tilage, or not infrequently nearly -5 an inch above that point. The omo-hyoid crosses it opposite the cricoid cartilage, and at about the same level the artery is crossed by the middle thyroid vein. The line of the internal jugular vein is just external to ( that for the main artery. Both artery and vein lie under the anterior border of the sterno- mastoid. The superior thyroid artery comes off below the great cornu of the hyoid bone, and curves forwards and downwards to the upper edge of the thyroid cartilage. The great cornu of the hyoid serves as an excellent guide to the lin- gual artery, which invariably forms a loop above the posterior end of that process before proceed- ing forwards beneath the hyo-glossus (Fig. 35, p. 137). The facial artery is very tortuous, but its general course in the neck is represented by a line drawn from the anterior border of the masseter at the lower border of the mandible to a point just above the tip of the great cornu, while the 176 THE HEAD AND NECK [CHAP. occipital follows a line that starts from the latter point and runs across the base of the mastoid process. The external jugular vein follows a line drawn from the mandibular angle to the middle of the clavicle. The subclavian artery describes a curve at the root of the neck (Fig. 44). One end of the curve corresponds to the sterno-clavicular joint, the other VISION OF CAROTID STERNO- MASTOID ^SUBCLAV. ART. VERT. ART. Fig. 44. Diagram showing the surface markings for the brachial plexus, subclavian and carotid arteries. end to the centre of the clavicle, the summit of the curve rising to a point about ^ an inch above that bone. In the angle between the posterior edge of the sterno-mastoid and the clavicle the pulsa- tions of the artery may be felt. Just above the clavicle the artery may be compressed against the first rib. The compression is most easily applied when the arm is well drawn down, and the direction of the pressure should be downwards and backwards, for it must not be forgotten that the first rib descends as it passes forwards under ix] NERVES OF THE NEGK 177 the clavicle. The* subclavian vein lies below the artery, and is entirely under cover of the clavicle. The suprascapular and transverse cervical arte- ries run parallel with the clavicle, the former quite behind the bone, the latter just above it. The pulsations of the latter vessel can generally be felt. Nerves. The position of the chief superficial nerves of the neck may be fairly indicated by six lines, all drawn from the middle of the pos- terior border of the sterno-mastoid muscle. A line drawn forwards from this spot so as to cross the sterno-mastoid at right angles to its long axis corresponds to the superficial cervical nerve (nervus cutaneus colli). A second line drawn up across the muscle to the back of the pinna, so as to run parallel with the external jugular vein, corresponds to the great auricular nerve; and a third line, running along the posterior border of the sterno-mastoid muscle to the scalp, marks the course of the small occipital nerve. These lines, continued downwards so as to cross the sternum, the middle of the clavicle, and the acromion, will indicate respectively the anterior, middle, and posterior supraclavicular nerves. The spinal accessory nerve reaches the anterior border of the sterno-mastoid muscle at a point about 1 inch below the tip of the mastoid process. It emerges from beneath that muscle about the middle of its posterior border, crosses the pos- terior triangle, and passes beneath the trapezius between the middle and lower thirds of the anterior border of that muscle (Fig. 35, p. 137). The phrenic nerve commences deeply at the side of the neck, about the level of the mid-point of the thyroid cartilage, and runs downwards to a point behind the sternal end of the clavicle. About the level of the cricoid cartilage it lies beneath the sterno-mastoid (which covers it whoHy in the neck) about midway between the anterior and posterior borders of the muscle. The brachial plexus can be felt, and even seen in very thin 178 THE HEAD AND NECK [CHAP. subjects. Its upper limits may be represented by a line drawn across the side of the neck from a point about opposite to the crico-thyroid space to a spot a little external to the centre of the clavicle (Fig. 44). The skin in the submandibular region is lax and thin, and is often found of considerable value for making flaps in plastic operations about the mouth. The platysma myoides is closely con- nected with the skin, and to its action is due the turning-in of the edges of such wounds as are athwart the line of direction of the muscle. The amount of subcutaneous fat in the cervical re- gion varies in different parts. In the suprahyoid region it is apt to undergo extensive development, producing the diffused lipoma known as " double- chin." The skin over the nape of the neck is very dense and adherent, and these two circumstances, in addition to the free nerve supply of the parts, serve to explain the severe pain that often accom- panies inflammation in this region. Common car- buncle is very often met with here, at the root of the neck, in the middle line. When the steriio-mastoicl muscle of one side is rigidly contracted, either from paralysis of the opposite muscle or from spasmodic contraction, or from some congenital defect, the condition known as wry-neck is produced. The position of the head in wry-neck illustrates precisely ^the effect of the sterno-mastoid when in full action. The head is bent a little forwards, the chin is turned towards the sound side, and the ear on the affected side leans towards the sterno-clavicular joint. In many cases the trapezius and splenius muscles are also affected. Spasmodic contraction of the muscle may be due to reflex irritation. Thus, it has accompanied inflammation of the cervical glands in the posterior triangle. Such inflammation has irritated some branches of the cervical plexus, and the sterno-mastoid muscle, although it is supplied mainly by the spinal acces- ix] WRY-NECK 179 so ry nerve, receives a nerve from that plexus (viz. from the second cervical). The course of the reflex disturbance in such cases is therefore not difficult to follow. It is to be remembered, too, that the spinal accessory nerve passes between the upper two or three deep cervical lymph-glands, which may compress it. A like contraction has also been produced by direct irritation of the second cervical nerve in cases of disease of the first two cervical vertebrae. For the relief of some forms of wry-neck, the sterno-mastoid muscle is divided subcutaneously, as in an ordinary teno- tomy operation, about J an inch above its attach- ment to the sternum and clavicle. Two structures stand considerable risk of being wounded in this operation, viz. the external jugular vein lying near the posterior border of the muscle, and the anterior jugular which follows its anterior border and passes behind the muscle, just above the clavicle, to terminate in the first-named vein. With common care, there should be no risk of wounding the great vessels at the root of the neck. For spasmodic wry-neck, the spinal accessory nerve and the communicating branches of the second and third cervical nerves have been cut. The spinal accessory nerve, as already stated, is found at the anterior border of the sterno- mastoid, 1 inch below the mastoid process. There is a curious congenital tumour, or in- duration, sometimes met with in this muscle in the newly born. It is usually ascribed to syphilis, but, in most cases, is probably due to some tear- ing of the muscle fibres during the process of delivery. Cervical fascia. To the connective tissue which binds together the muscles, vessels, nerves, and glands of the neck the name of cervical fascia is given. It consists of the sheaths of the muscles, vessels, and nerves. These sheaths are united together in such a manner as to allow free movements of the oesophagus, larynx, trachea, and thyroid body, and yet to give a ISO THE HEAD AND NECK [CHAP. firmness and solidity so that the neck may be moved as a whole. Besides serving as a medium for binding the various structures of the neck together, the cervical fascia forms the supporting tissue in which the extensive lymphatic system of the neck is embedded and conveyed towards the root of the neck, The deep cervical fascia may be divided into (A) the superficial layer, and (B) the deeper pro- cesses (see Fig. 45). (A) The superficial layer forms a complete investment for the neck, and covers in all the cervical structures, except the platysma and some superficial veins and nerves, with the complete- ness of a perfectly fitting cravat. It commences as a thin layer behind at the spinous processes of the vertebrae, and, having invested the trapezius muscle, starts at the anterior border of that muscle, as a single layer, to cross the posterior triangle. Arriving at the posterior border of the sterno-mastoid muscle, it splits to enclose that structure, appearing again as a single layer at the anterior border of the muscle, whence it passes to the middle line of the neck to join the fascia of the opposite side, entirely covering in, on its way, the anterior triangle. The part that occupies the posterior triangle is loose and open in texture, and is continuous with the connective tissue of that triangle. Over the anterior triangle the fascia is attached above to the lower border of the mandible. Behind that bone it passes over the parotid gland to the zygoma, forming the parotid fascia, while a deeper layer passes beneath the gland (between it and the submandibular gland), to be attached to points at the base of the skull. It is from this deeper part that the stylo-mandi- bular ligament is developed. In front the fascia is attached to the hyoid bone, and just below the thyroid body it divides into two layers again, one to be attached to the front of the sternum and the other to the back. Both of these layers lie in front of the depressors of the hyoid bone, and they form IX] CERVICAL FASCIA 181 between them a little space (which extends so far laterally as to enclose the sternal head of the sterno-mastoid), the widest part 9f which is below, and which there corresponds in width to the thickness of the sternum. It will be perceived that, in dividing the sternal head of the sterno- mastoid, the operation is performed within this little chamber formed by the two layers just Fig. 45. Transverse section through the lower part of the neck, to show the arrangement of the cervical fascia. (Diagrammatic. ) a, Trapezius ; b, sterno-mastoid ; c, depressors of hyoid bone ; d, pla- tysma ; e, anterior spinal muscles ; /, scalenus anticus ; g, carotid artery ; h, external jugular vein ; ?', posterior spinal muscles ; T, trachea, with gullet behind and thyroid body in front. named, and it is well to note that the anterior jugular vein also occupies this chamber on its way to the external jugular trunk. (B) The deeper processes. (1) From the super- ficial layer a process comes off near the anterior border of the sterno-mastoid muscles, which, passing 182 THE HEAD AND NECK [CHAP. beneath the depressors of the hyoid bone, invests the thyroid body and front of the trachea, and runs down, in front of that tube and of the large vessels, to the fibrous layer of the peri- cardium. (2) The prevertebral fascia is a layer that descends on the prevertebral muscles behind the pharynx and gullet. It is attached above to the base of the skull, and, below, descends into the thorax, behind the oesophagus. Laterally, it joins the carotid sheath, and is then prolonged outwards and downwards over the scalene muscles, the brachial plexus, and the subclavian vessels. It follows these vessels beneath the clavicle, where it forms the axillary sheath and becomes con- nected with the under surfa.ce of the costo-cora- coid membrane. (3) The sheath of the carotid artery and its accompanying vein and nerve is continuous with the prevertebral and pretracheal layers and with the sheath of the sterno-mastoid (Fig. 45). The carotid sheath descends with the pre- tracheal layer, to end in the sheath of the aorta and pericardium. Hence, in a sense, the heart and pericardium are supported from the neck; when the head is thrown back the carotid sheaths become tense and the thoracic structures are lifted upwards. In many cases a cervical abscess has burst into the gullet^ or trachea, and even into the pleura. In some instances the great vessels have been opened up. In one remarkable case reported by Savory (Med.-Ghir. Trans., 1881), not only was a considerable portion of the common carotid artery destroyed by the abscess, but also a still larger portion of the internal jugular vein and a large part of the vagus nerve. This, and like examples of the destructive action of some cervical abscesses, depend, no doubt, upon the unyielding character of the cervical fascia, which hems in the pus on all sides, and drives it to resort to desperate measures to effect an escape. "It is noteworthy," remarks Jacobson, "that communi- cations between abscesses and deep vessels have ix] CERVICAL RIBS 183 usually taken place beneath two of the strongest fasciae in the body, the deep cervical fascia and the fascia lata" (Hilton's "Rest and Pain"). The apex of the hm$r extends into the neck, and reaches a point from 1 to 2 inches above the inner half of the clavicle. A point between the sternal and clavicular heads of the sterno-mastoid and 1| inches above the clavicle will, in the majority of adults, mark the highest point of the apex and the position of the neck of the first rib. It lies behind the clavicle, anterior scalene muscle, and subclavian vessels. The right lung commonly extends higher up than the left. The pleura has been opened in careless opera- tions on the subclavian artery, and has also been torn in dragging deep-seated tumours from the base of the neck. The pleura and lung have been wounded in stabs of the neck and by fragments of bone in severe fractures of the clavicle. Cer- vical abscesses have opened into the pleura, and, apart from this, pleurisy has followed inflamma- tion of the cellular tissue at the root of the neck. Sibson's fascia, which is attached along the inner border of the first rib, strengthens the pleura over the apex of the lung. Cervical ribs. These structures have led to many errors in diagnosis, have been mistaken for exostoses, and, where the subclavian artery is car- ried over them, which is usually the case (Fig. 46), have led to the diagnosis of aneurysm. They are met with in from 1 to 2 per cent, of all individuals, but rarely give rise to symptoms until adult years are reached. They represent the ribs which are normally developed in some lower vertebrates. In most cases a cervical rib is found on either .side of the seventh ^cervical vertebra; sometimes it is movable, sometimes it is ankylosed to the vertebra and its transverse process. A rudiment is always present in the foetus. It may be very short, and represented only by a head, neck, and tubercle. Such forms have been mistaken for exostoses. It may be long, and may then end free, or be 184 THE HEAD AND NEGK [CHAP. joined to the first rib or the first costal cartilage by ligament, or even by cartilage. In such in- stances the subclavian artery passes over the cervical rib, its pulsations being very distinctly seen and felt. To the longer form of cervical ribs the scalenus anticus and the scalenus medius FIFTH CERV./IECVE [CAROTID TUBERCLE IJ.TRACMEA 4.EICMTM CERV./IECVE CERVICAL RIB ART E+CAROTID ART. 5iBSOM's FASCIA ART. ^CLAVICLE Fig. 46. Showing the relationship of the subclavian artery and brachial plexus to a cervical rib. may be attached. Occasionally subjects of this anomaly complain of numbness along the ulnar side of the arm and hand, or of partial paralysis of the muscles of the hand. These symptoms are due to traction on the first dorsal nerve at the point where it crosses above the cervical rib (Thorburn). {See Fig. 46.) Cervical ribs with ix] WOUNDS OF THE NEGK 185 associated pressure symptoms may be traced through several generations of the same family (Theodore Thompson). In thin subjects the rib can be seen as a distinct projection in the neck. Prof. Wood- Jones has pointed out that the groove on the upper surface of the first rib is occupied, when the arm hangs by the side, uot by the subclavian artery but by the lowest trunk of the brachial plexus formed by the eighth cervical and first dorsal nerves. He has also shown that the groove is deepest, and the pres- sure between the nerve trunk and rib therefore greatest, in those cases where a considerable part of the second dorsal nerve enters into the forma- tion of the lowest trunk of the brachial plexus. 4 Hi throat and wounds of the neck. The skin of the neck is so elastic and mobile that it is readily thrown into folds when a knife, and especially a blunt knife, is drawn across it. Thus in cases of cut throat several distinct skin- cuts may be found that were all produced by one movement of the knife. The wound in cut throat, whether suicidal or homicidal, most frequently involves the thyro-hyoid membrane, next in fre- quency the trachea, and then the thyroid car- tilage. (See Fig. 44, p. 17G.) 1. If the wound be above the hyoid bone the following parts may be cut : Anterior jugular vein ; anterior belly of digastric ; mylo-hyoid, genio-hyoid, genio-glossus, and hyo-glossus mus- cles; the lingual artery; branches of the facial artery; the hypoglossal and lingual nerves; the submandibular gland. The substance of the tongue may be cut, and the floor of the mouth freely opened. In any case where the attachments of the tongue are divided the organ is apt to fall back upon the larynx and produce suffocation. 2. If the wound be across the thyro - hyoid space the following may be the parts cut: Ante- rior jugular vein; sterno-hyoid, thyro-hyoid, omo- hyoid muscles; thyro-hyoid membrane; inferior constrictor; superior laryngeal nerve; superior 186 THE HEAD AND NECK [CHAP. thyroid artery; and if it be near the hyoid bone the trunk of the lingual artery may be cut. The pharynx would be opened in a deep wound, and the epiglottis divided near its base. Division of the epiglottis in wounds in this situation is always a serious complication. 3. If the wound involve the trachea the follow- ing may be the parts cut : Anterior jugular vein ; sterno-hyoid, sterno-thyroid, and omo-hyoid muscles ; part of sterno-mastoid ; thyroid gland ; superior and inferior thyroid arteries; superior, middle, and inferior thyroid veins; recurrent laryngeal nerves and the gullet. In wounds of the neck the great vessels often escape in a marvellous manner. They are pro- tected in part by the depth at which they are situated, and in part by their great mobility, lying as they do in an environment of loose con- nective tissue. Dieffenbach relates a case of cut throat in which both gullet and trachea were divided without any damage to the great vessels. In cut throat the vessels are greatly protected by the projecting thyroid cartilage above and by the contracting of the sterno-mastoid muscles below. Deep gashes made across the crico-thy- roid space, or through the upper part of the trachea, reach the great vessels more easily than wounds made with equal force in any other part of the neck. In some cases of gunshot wound the vessels seem to have been actually pushed aside, and to have owed their safety to their mobility. Thus, in a case reported by Longmore, the bullet passed entirely through the neck from one side to the other. It passed through the gullet, damaged the posterior part of the larynx, but left the great vessels intact. In another recorded case a boy fell upon the point of a walking-stick. The end of the stick passed entirely through the neck from side to side, entering in front of one sterno- mastoid muscle and emerging through the sub- stance of the opposite one. It probably passed ix] FRACTURE OF THE HYOID BONE 187 between the pharynx and the spine. The boy. who left the hospital well in eighteen days, owed his safety to the laxity of the cervical connective tissue and to the mobility of the main structures in the neck. The structures of the neck are fixed laxly to allow movements of the larynx and tongue. In connexion with the subject of wounds of the neck, it must be remembered that the most im- portant part of the spinal cord can be reached from behind, through the gap between the atlas and axis. In this situation the cord has been divided by one stab of a knife, the instrument entering between the two bones. Langier gives some ingenious cases of infanticide where the lethal weapon was merely a long needle. The needle was introduced into the spinal canal be- tween the atlas and the axis, and the cord readily cut across. The Iiyoid bone may be broken by direct vio- lence, as from blows, or in the act of throttling. It is sometimes found broken in those who have been hanged. The fracture may involve the body of the bone, but more usually the greater cornu is found broken off. In the New York Medical Record (1882) is published the leport of the case of a man who felt something snap under his chin while yawning. On examination the hyoid bone was found to be fractured. The bone was also found broken in a patient who threw her head violent! v backwards to save herself from fall- ing (Hamilton). The fracture is associated with great difficulty and pain in speaking, ^ in moving the tongue, in opening the mouth, and in swallow- ing symptoms that may be readily understood. A bursa lies between the thyro-hypid membrane and the posterior surface of the hyoid bone. When enlarged, it may form one of the cystic tumours of the neck. i aryn* mid trachea. The position of the larynx in the neck is influenced by age. In the adult the cricoid cartilage reaches to the lower 188 THE HEAD AND NECK [CHAP, part of the sixth cervical vertebra. In a child of three months it reaches the lower border of the fourth cervical, and in a child of six years the lower border of the fifth vertebra. At puberty it attains the adult position. The upper end of the epiglottis in the adult is opposite the lower border of the third cervical vertebra. With the laryngoscope the following parts may be made out (Fig. 47) : The base of the tongue and the glosso-epiglottic folds; the superior aperture of the larynx, presenting in front the epiglottis, the cushion of the epiglottis (Fig. 47, A), at the sides the aryteno-epiglottidean folds (in which are two rounded eminences corresponding to the cornicula and cuneiform cartilages), and at the back the arytenoid commissure of mucous membrane. Deep down can be seen the true and false vocal cords, the ventricle, the anterior wall of the larynx, a little of the cricoid cartilage, and more or less of the anterior wall of the trachea. If the glottis be very fully dilated the openings of the two bronchi may be dimly seen. The thyroid and cricoid cartilages and the greater part of the arytenoid are in structure hyaline, as are the costal cartilages. Like the last-named, they are liable to become more or less ossified as life advances. Ossification commences in the thyroid and cricoid cartilages at about the age of 20, and in either cartilage the process commences in the vicinity of the crico-thyrpid joint. The arytenoid ossifies later. Ossification of the laryngeal cartilages is more marked in males than in females. The larger cartilages are liable to be fractured by violence, as by blows, throttling, etc. The thyroid is the one most fre- quently broken, and usually in the median line. The posterior superior angle of the thyroid car- tilage marks the position of the pyriform fossa, a wide recess, above and external to the aryteno- epiglottic folds (Fig. 47). Foreign bodies may be arrested in this fossa. IX] RIMA GLOTTIDIS 189 The riraa glottidis is the aperture between the true vocal cords and the vocal process of the aryte- noid cartilages, to which the cords are attached posteriorly. The cords are double the length of the processes, and are of a grey-buff colour, owing to the elastic tissue, of which they are mainly composed, being apparent beneath the stratified epithelium. The rima is the narrowest part of the interior of the larynx, and it is well to be familiar with its proportions in reference to the i 2 Fig. 47. Upper aperture of the larynx in the open (1) and shut (2) positions. JL, Cushion of epiglottis ; B, apices of arytenoids ; c, aryteno-epi- glottidean folds : E. posterior aspect of cricoid ; F, false vocal cords ; G, rima glottidis, between true vocal cords ; H, posterior border of thyroid cartilage ; I, tip of great horn of hyoid. entrance of foreign bodies and the introduction of instruments. In the adult male the rima mea- sures nearly 1 inch (23 mm.) from before back- wards ; f roin side to side, at its widest part, it measures about one-third of the length; this dia- meter may be increased to one-half of the length in extreme dilatation. In the female and in the male before puberty the antero-posterior diameter is from 17 mrn^ The rima is widely opened dur- ing inspiration, owing to the action of the crico- arytenoideus posticus, while the vocal cords are 190 THE HEAD AND NECK [CHAP. approximated in speech under the influence of the crico-arytenoideus lateralis (Fig. 48). The mucous membrane of the larynx varies in thickness in different parts, and in the amount of its submucous tissue. The membrane is thick- est, and the submucous tissue most abundant, in the following parts, taken in order of degree: the aryteno-epiglottidean folds, the mucous mem- brane of the ventricle, the ventricular folds (false vocal cords), and the laryngeal aspect of the epiglottis. These are the parts that become !NF. CONSTRICT. AftYTEMOID MUSCLE -EPIGLOT.FOLD HT.-AKYTEN . FOLD ARYTENOIP CARTILAGE L - F - r COffO (pAR Fig. 48. A, Coronal vertical section of the larynx, showing the vocal cords, ventricles, ventricular folds, and thyro - arytenoid muscles ; B, the rima glottidis seen from above, with the left cord in the position of adductor paralysis, and the muscles which move the arytenoid cartilages indicated on the right. most congested and swollen in acute laryn- gitis ; and the serious condition known as oedema of the glottis depends mainly upon effusion into the lax submucous tissue in the aryteno- epiglottidean folds. The lax condition of the mucous membrane of the aryteno-epiglottidean folds allows free movements of the arytenoid cartilages and complete closure of the upper aperture of the larynx (Fig. 47). The mucous membrane is firmly bound to the true vocal cords and covered by stratified epithelium, while the ix] DYSPHONIA CLERIGORUM 191 rest of the larynx is lined, like the trachea, with ciliated epithelium. Owing to the nature of its covering and exposure to friction, the true vocal cord is not an uncommon site of epithelioma. The affection known as " clergyman's sore throat ''" has an interesting anatomical basis. The mucous membrane of the larynx is well provided with mucous glands, whose function it is to keep moist the parts concerned in phonation. When an in- dividual speaks aloud for a long time the lining of the larynx tends to become dry, on account of the large amount of cold air that is drawn in directly through the mouth. To keep these parts moist the mucous glands have to exhibit increased energy, and in those who speak much in public the glands may in time become so over- worked as to inflame. It is the inflammation of these glands that constitutes the present affec- tion. The glands are not distributed equally over all parts of the larynx, but are most numerous in the membrane covering the arytenoid cartilages and parts immediately about them, the base of the epiglottis, and the interior of the ventricle. It is in these parts, therefore, that the changes in chronic glandular laryngitis, or dysphonia clericorum, are most marked. Excision of the larynx. The entire larynx has been removed for carcinomatous disease, but the operation, although not immediately fatal, has not been followed by very satisfactory results.. It is removed through an incision in the middle line. In this incision are divided the platysma, the fascia, and the anterior jugular vein. The larynx is separated from its connexions, the fol- lowing structures being divided : sterno-thyroid, thyro-hyoid, stylo-pharyngeus, palato-pharyngeus, and inferior constrictor muscles, the laryngeal branches of the superior and inferior thyroid arte- ries, the superior and inferior laryngeal nerves, the hyo-epiglpttic and glosso-epiglottic ligaments. The larynx is then separated from the trachea, and is dissected off from below up. In separating 192 THE HEAD AND NECK [CHAP. gullet and pharynx there is great risk of " button- holing " the former tube. Growths and foreign bodies may be removed from the larynx by the operation of thyrotomy : the two alas of the thyroid are separated along the middle line and pulled apart, thus exposing the interior of the larynx. In subjects over 45 years of age the cartilage be- comes ossified in the middle line, and will require division by a fine saw. It should be remembered that the vocal cords are attached on each side of the median line near the mid-point of the anterior border of the thyroid cartilage, while just above them are fixed the ventricular folds or false vocal cords and stalk of the epiglottis. The lymphatic vessels of the upper half of the larynx follow the superior laryngeal vessels and pass to the upper deep cervical glands. A small lymphatic gland, the first to become the seat of secondary cancerous deposit, is situated below the horn of the hyoid on the thyro-hyoid mem- brane (Fig. 50, p. 207). The lymphatics of the lower half of the larynx accompany the inferior thyroid vessels and pass through lymph-glands by the side of the trachea. Tracheotomy and laryngotomy. The trachea measures about 4j inches in length, and from f to 1 inch in its extreme width. It is surrounded by an atmosphere of very lax connective tissue, which allows a considerable degree of mobility to the tube. The mobility of the trachea is greater in children than in adults, and adds much to the difficulties of tracheotomy. In this procedure the windpipe is opened in the middle line by cutting two or three of its rings above, below, or through the isthmus of the thyroid gland. Since the trachea, as it descends, lies farther from the sur- face, and comes in relation with more and moro important structures, it is obvious that, other things being equal, the higher in the neck the operation can be done the better. The length of trachea in the neck is not so considerable as might at first appear, and, according to Holden, ix] TRACHEOTOMY 193 not more than some seven or eight of the tracheal rings (which number sixteen to twenty in all) are usually to be found above the sternum. The dis- tance between the cricoid cartilage and the sternal notch varies greatly, and depends upon the length of the neck, the age of the patient, and the posi- tion of the head. If 2 inches of trachea are ex- posed above the sternum when the head rests easily upon the spine, then in full extension of the head some | of an inch more of the windpipe will, as it were, be drawn up into the neck. According to Tillaux, the average full distance between the cricoid cartilage and the sternum is, in the adult, about 2f inches (7 cm.). The full distance in a child between 3 and 5 years is about 1^ inches (4 cm.), in a child between 6 and 7 years about 2 inches (5 cm.), and in children between 8 and 10 years about Z^ inches (6 cm.). As may be imagined, the dimensions of the trachea on section vary greatly at different ages, and even in different individuals of the same age. This leads to the question as to the proper diameter of tracheotomy tubes. Guersant, who has paid much attention to this matter, says that the dia- meter of the tubes should run from 6 mm. to 15 mm.* The tubes with a diameter of from 12 mm. to 15 mm. are for adults. For children under 18 months the diameter of the tube should be about 4 mm. In performing tracheotomy it is most im- portant that the head be thrown as far back as possible, and that the chin be kept strictly in a line with the sternal notch, so that the relations of the jniddle line of the neck be preserved. Full extension of the head not only gives the surgeon increased room for the operation, but also brings the trachea nearer to the surface, and by stretch- ing the tube renders it much less mobile. In cutting down upon the trachea in the middle line of the neck from the cricoid cartilage * The reader may be reminded that 12';j mm. = about i in., and 6 mm. therefore = about \ in. H 194 THE HEAD AND NECK CHAP, to the sternum the following parts are met with : Beneath the integument lie the anterior jugular veins. As a rule these veins lie some little way apart on either side of the median line, and do not communicate except by a large transverse branch which lies in the interfascial space at the upper border of the sternum. Sometimes there are many communicating branches right in front of the tracheotomy district, or the veins may form almost a plexus in front of the trachea, or there may be a single vein which will follow the middle line. Then comes the cervical fascia, enclosing the sterno-hyoid and sterno-thyroid muscles. The gap between the muscles of opposite sides is lozenge-shaped, and is such that the trachea can be exposed without dividing muscle fibres. The isthmus of the thyroid usually crosses the second, third, and fourth rings of the trachea. Above it a transverse communicating branch be- tween the superior thyroid veins is sometimes found. Over the isthmus is a venous plexus, from which the inferior thyroid veins arise, while be- low the isthmus these veins lie in front of the trachea together with the thyroidea ima artery (when it exists). The inferior thyroid vein may be represented by a single trunk occupying the middle line. In the infant before the age of 2 years the thymus extends up for a variable distance in front of the trachea. At the very root of the neck the trachea is crossed by the innomi- nate and left carotid arteries and by the left innominate vein; and lastly, abnormal branches of the superior thyroid artery may cross the upper rings of the windpipe. The evil of wounding the thyroid isthmus is exaggerated. I (F. T.) have frequently divided this structure in performing tracheotomy, without any inconvenience resulting. Like other median raphes, the middle line of the thyroid isthmus has but & slight v-ascularity, and it has been shown that one side of the thyroid gland can only be par- tially injected from the other (i.e. by injection that ix] , LARYNGOTOMY 195 crosses the isthmus). The difficulty of tracheotomy in infants depends upon the shortness of the neck, the amount of the subcutaneous fat, the depth at which the trachea lies, its small size, its great mobility, and the ease with which it can be made to collapse on pressure. To the finger, roughly introduced, the infant's trachea offers little resistance. Its mobility is such that we hear of its being held aside unknowingly by re- tractors while the operator is scoring the oeso- phagus (Durham). In the child, too, the great vessels often cross the trachea higher up than in the adult, and some inconvenience may also arise from an unduly prominent thymus. In one case, in an infant, the end of a tracheotomy tube press- ing on the front of the trachea produced an ulcer that opened the innominate artery (Brit. Med. Journ., 1885). In introducing the cannula, if the tracheal wound be missed, it is easy to thrust the instrument into the lax tissue beneath the cervical fascia and imagine that it is within the windpipe. In laryngotomy the air-passage is opened by a transverse cut through the crico-thyroid mem- brane. The crico-thyroid space only measures about \ an inch in vertical height in well-, developed adult subjects, while in children it is much too small to allow of a cannula being in- troduced. The crico-thyroid arteries cross the space, and can hardly escape division. They are, as a rule, of very insignificant size, and give no trouble. Occasionally, however, these vessels are large, and "cases are recorded in which serious and even fatal haemorrhage has occurred from these vessels " (Durham). In introducing the cannula it may readily slip between the crico- thyroid membrane and the mucous lining instead of entering the trachea. Foreign bodies often find their way into the air-passages, and they have been represented by articles of food, teeth, pills, buttons, small stones, and the like. They are usually inspired during 196 THE HEAD AND NECK [CHAP, the act of respiration, and may lodge in the superior aperture of the larynx, or in the rima, or find their way into the ventricle, or lodge in the trachea, or enter a bronchus. If a foreign substance enters a bronchus it usually selects the right, that bronchus having its aperture more immediately under the centre of the trachea than has the left tube. On one occasion, in a dissecting- room subject, I (F. T.) found two threepenny pieces lying side by side, in the right bronchus, so as entirely to block the tube. The danger of inhaled foreign substances depends not so much upon the mechanical obstruction they offer as upon the spasm of the glottis they excite by reflex irrita- tion. A body may, however, lodge in the ventricle for some time without causing much trouble, as in a case reported by Desault, where a cherry- stone lodged for two years in this cavity without much inconvenience to its host. In one strange case a bronchial gland found its way into the trachea by producing ulcer ation of that tube, was coughed up, and became impacted in the rima glottidis. The patient was saved from immediate suffocation by tracheotomy. Thyroid body. Each lobe of this body should measure about 2 inches ^ in length^ l inches in breadth, and f of an inch in thickness at its largest part. When distinctly beyond these mea- surements the thyroid may be considered to be enlarged. Its usual weight is between 1 and 2 oz. Of the three surfaces (Fig. 49), the anterior is covered by the infrahyoid muscles, its inner rests on the larynx and trachea, while its outer or posterior covers the carotid sheath. Its promi- nent posterior border is in contact at its lower part with the recurrent laryngeal nerve and oesophagus. Each lobe extends from about the middle of the thyroid cartilage to the sixth ring of the trachea. It is larger in females than in males, and the right lobe is usually larger than the left. In connexion with these matters it may be noted that thyroid enlargements (bronchocolo, IX] THYKO1D GLAND 197 goitre) are more common in females than in males, and in any case are more apt to be first noticed on the right side. The body being closely adherent to the trachea and larynx, it follows that it moves up and down during deglutition, and this circumstance is of the utmost value in the diagnosis of bronchocele from other cervical tumours. A strong process of cervical fascia (the suspensory ligament of Berry) binds the gland to each side of the cricoid cartilage, and has to be severed before complete removal is possible. The ANT. JUG. VEIN \ TRACHEA STERNO-HYOID STERNO-THYROIO STERNO-MASTOlD JUQ. VEIN CAROTID ART. RECURRENT LARYNQ. TRACHEA / OESOPHAGUS OMO-HYOID INF. THYROID ART. VERT. ART. THYROID BODY Fig. 49. Diagrammatic section to show the relations of the thyroid body. thyroid when enlarged may distort and narrow the trachea, and this is all the more likely to be the case when the enlargement occurs rapidly, since the body is held down by the sterno-hyoid, sterno-thyroid, and omo-hyoid muscles. The pos- terior or outer surface of the thyroid body being in contact with the sheath of the great vessels, it follows that the gland when enlarged may readily receive pulsations from those vessels (Fig. 49). It generally touches also the lower part of the pharynx, and the upper part of the gullet behindhand enlargement in this direction may, in 198 THE HEAD AND NECK [CHAP. connexion with the interference with the move- ment of the larynx in deglutition, serve to ex- plain the difficulty in swallowing often noticed in bronchocele. The isthmus of the thyroid gland is developed from a diverticulum which is protruded from the ventral wall of the pharynx in the -embryo between the mandibular and hyoid parts of the tongue (Fig. 51, p. 210). The foramen caecum of the tongue represents the point at which the diver- ticulum grew out from the pharynx. From this foramen a duct (the thyro-glossal) may be found to lead to accessory gland masses about the hyoid bone. In the vicinity < of this bone accessory glands and small cysts lined with epithelium are not infrequently met with. These glands, to- gether with the so-called pyramid or middle lobe, are the remains of the neck of the primitive diver- ticulum. Below the level of the hyoid bone the median bud divides ; hence the pyramidal lobe represents the stalk of the right or of the left division and is never in the median line. The pyramid, which is nearly always connected to the hyoid bone by the levator thyrpidese, exists in 79 per cent, of the subjects examined (Streckeisen). The lateral lobes are developed from the fourth visceral clefts (Fig. 51). The median diverticulum occasionally fails to join one of the lateral, in which case the isthmus is partially absent. Small accessory thyroid bodies are frequently present. The parathyroid bodies appear to play an essential part in the function of the thyroid. They are of the size of small peas, and have a structure similar to that of the medulla of the suprarenal bodies, the cells being grouped in reticulating columns. Two are usually found on each side, one behind the lower pole of the lateral lobe, the other behind the lobe amongst the ter- minal branches of the inferior thyroid artery. Parathyroid bodies become less numerous as age advances, so that in the aged none may be found (Forsyth). The parathyroid bodies may develop ix] MYXCEDEMA 199 vesicles containing colloid material, and thus be- come very similar to small accessory thyroids. Atrophy of the thyroid gland, or its destruc- tion by disease, is apt to lead to a general con- dition of the body known as myxcedema. The condition closely resembles cretinism, especially as met with in goitrous subjects. Myxoedema may follow the entire excision of the thyroid by opera- tion, and has been produced in monkeys by ex- perimental removal of the gland. One prominent feature of myxredema is the swelling of the sub- cutaneous tissues from an accumulation therein of a mucinoid substance. Vaso-motor nerves reach the thyroid through the lower part of the cervical sympathetic chain, and by the same course nerves pass upwards to the eye (see p. 64). These nerves appear to be connected centrally, probably in the medulla, for in certain conditions enlargement of the thyroid is accom- panied by protrusion of the eye (exophthalmic goitre). The lymphatics of the thyroid gland are numerous, and pass to the deep cervical and superior mediastinal lymph-glands. Asher and Flack found that the internal secretion of the thyroid body could be increased by stimulation of the laryngeal nerves. The superior thyroid artery reaches the gland at the apex of the lateral lobe; the inferior thyroid artery enters the lower part of the lobe at its posterior aspect. In securing this vessel, and in liberating the lower part of the gland during excision, the recurrent laryngeal nerve is in great danger of being damaged. If it be cut or included in a ligature, all the muscles of the larynx on that side become paralysed, save the crico-thyroid. The thyroidea ima artery, an extra vessel to the thyroid body, which usually arises from the innominate and ascends in front of the trachea, is found in one subject out of every ten. The gullet commences opposite the sixth cervical vertebra, and pierces the diaphragm 200 THE HEAD AND NEGK [CHAP. opposite the tenth dorsal vertebra. The point is marked on the back by the overlapping spine of the ninth dorsal vertebra. By placing the stetho- scope a little to the left of this spine, fluid may be heard to enter the stomach. The gullet pre- sents three curves : one is antero-posterior, and corresponds to the curve of the spinal column ; the other two are lateral. Commencing at the middle line, it deviates slightly to the left as far as the root of the neck; thence to the fifth dorsal vertebra it gradually returns to the middle line, and finally it turns again to the left, at the same time passing forwards, to pierce the diaphragm. Notwithstanding these natural curvatures, a rigid and straight gastroscope can, in expert hands, be passed from mouth to stomach. Its length is from 9 to 10 inches. There are three narrow parts in the gullet one at its commence- ment, one about 2| inches from that point, and a third where the tube passes through the dia- phragm. The narrowing at the commencement and termination of the oesophagus is due to the fact that the musculature at these points is sphincteric in nature, and, except during the pas- sage of food, the lumen in these parts is closed. Under certain conditions the sphincter at the lower end of the oesophagus passes into a state of spasm leading to dilatation of the oesophagus from accumulation of food. In its open state the diameter at each of these points is a little over ^ an inch (14 mm.) ; the diameter elsewhere is about f of an inch (17 mm. to 21 mm.). By forcible distension the two upper narrow parts could be distended to a diameter of 18 to 19 mm., the lower part to 25 mm., and the rest of the gullet to a diameter of nearly 1| inches (35 mm.). Foreign bodies when swallowed are most apt to lodge above one of the sphincters either at the com- mencement of the gullet or where it passes through the diaphragm to join the stomach. The same parts also are those most apt to show the effects of corrosives that have been .swallowed. A ixj FOREIGN BODIES IN THE (ESOPHAGUS 201 third point of arrest is where the oesophagus passes behind the left bronchus. Among the relations of the oesophagus, the following may be noted as receiving illustration in surgical practice : The gullet is in nearly all its course in close relation with the front of the vertebral column. In the neck the trachea is immediately in front of it. In the thorax it has the left bronchus, left bronchial glands, pericardium, and left auricle in front of it, while the two vagi form a plexus on it. The left bronchial glands, when enlarged, may press on the gullet, adhere to it, or even cause localized soften- ing and diverticula to spring from it. The thoracic duct passes behind to reach the left side of the gullet in the upper part of the thorax, while in the lower part the aorta, at first to the left of the oesophagus, gradually becomes pos- terior to it. It is, moreover, partly in contact with both pleurae, but more especially with the membrane of the right side ; and, lastly, the recur- rent laryngeal nerve ascends between it and the trachea. (See Figs. 57 and 102, pp. 241 and 455.) Foreign bodies impacted in the gullet are very apt to lead to ulcerations that may open ad- jacent f parts. Thus, in the Musee Dupuytren is a specimen showing a five-franc piece which had stuck in the gullet, and had produced an ulcer that had opened the aorta. In another instance a " smasher " swallowed a counterfeit half-crown Eiece. Eight months afterwards he died of semorrhage. The coin had sloughed into his aorta. In another case (Lancet, 1871), a fish-bone, lodged in the gullet opposite the fourth dorsal vertebra, had caused two perforating ulcers; one on the right side had caused plugging of the vena azygos major, while the other on the left had made a hole in the aorta. Less frequently, impacted foreign substances have found their way into the trachea and into the posterior mediastinum. Dr. Ogle reports a case (Path. Soc. Trans. > vol. iv.) where a piece of bone impacted in the gullet 202 THE HEAD AND NEGK [CHAP. induced ulceration of an inter vertebral disc subsequent disease of the spinal cord. Carcinoma of the gullet, also, when it spreads, is apt to invade adjacent parts, and especially to open into the trachea or bronchi. If it spreads to the pleura, it will usually involve the right pleura, as being the membrane more in relation with the gullet. Cancer of the gullet has so spread as to invade the thyroid body, the pericardium, and the lung, and has opened up the first intercostal artery in one case and the right subclavian in another. The sensory nerve supply of the oesophagus comes mainly from the fifth dorsal segment of the cord (Head). In cases of cancer or burns of the gullet, pain is referred to the skin of this seg- ment (see Fig. 79, p. 359). CEsophageal malformations. In the newly born the upper part of the cesophagus may end blindly, while the lower part commences by an opening in or near the bifurcation of the trachea, so that milk could reach the stomach only by first Eassing into the larynx and trachea. Death soon allows from suffocation or septic pneumonia. The condition is the result of a maldevelopment of the septum which ultimately separates the trachea and oesophagus. Hernial diverticula of the mucous membrane occasionally occur at the junction of the oesophagus and pharynx, immedi- ately above the upper sphincter of the oesophagus. They are named pharyngeal pouches, and pro- trude between the lower border of the inferior constrictor and the sphincteric fibres which sur- round the pharyngeal orifice of the oesophagus. The diverticula therefore arise opposite the cri- cpid cartilage. Since the fundus of the pouch lies between the upper end of the oesophagus and the spine, it necessarily, when filled with food, compresses the commencement of the oesophagus. The operation of oesophagotomy consists in incising the gullet for the purpose of removing an impacted foreign body. The gullet is usually ix] BRASDOR'S OPERATION 203 reached from the left side, since it projects more on that aspect. The incision is made between the sterno-mastoid and the trachea, in the same direc- tion as the incision for ligaturing the common carotid. The cut extends from the top of the thyroid cartilage to the sterno-clavicular joint. The omo-hyoid muscle is drawn outwards, or cut. The great vessels, larynx, and thyroid gland are drawn aside, and care must be taken not to wound these structures nor damage the thyroid vessels, thoracic duct, or the recurrent nerve. The gullet, when exposed, is opened by a vertical incision. Great cervical vessels. The course, rela- tions, and abnormalities of the great cervical vessels, with the operations whereby they may be ligatured, and the details pertaining to those procedures, are so fully given, not only in works on operative surgery, but also in the chief ana- tomical text-books, that nothing need be said upon the matter in this place. The main relationships of the carotid and subclavian arteries are shown in Fig. 44, p. 176. In Brasdor's operation a main trunk is ligatured on the distal side of an aneurysm, no branches intervening between the sac and the ligature. The cure by this measure depends upon the fact that blood does not con- tinue to go to parts when once the need for blood in them is diminished. Thus, after amputation at the hip-joint, the femoral artery, having no need to carry to the stump the amount of blood it brought to the limb, often shrinks to a vessel no larger than the radial. When an aneurysm low down in the carotid artery is treated by ligature of the vessel near its bifurcation by Brasdor's method, the blood, having now, as it were, no object in entering the carotid trunk, sodn ceases to fill the vessel entirely, and the artery (and in successful cases the aneurysm) shrinks in con- sequence. The cervical connective tissue being lax, aneu- rysms in this part can grow and spread rapidly, and usually soon produce " pressure symptoms." 204 THE HEAD AND NECK [CHAP. As examples of these may be .noted oedema and lividity of the face and of the upper limb from pressure upon the main veins, laryngeal symptoms from pressure upon the recurrent nerve or trachea, spasm of the diaphragm from pressure upon the phrenic nerve, damage to the sympathetic, and giddiness and impaired vision from anaemia of the brain. The vertebral artery has been ligatured with doubtful benefit in cases of epilepsy. It is sur- rounded by yaso-motor nerves derived from the inferior cervical ganglion, which also are neces- sarily tied. The artery is reached through an incision made along the posterior border of the sterno-mastoid muscle just above the clavicle (see Fig. 44, p. 176). The " carotid tubercle" is then sought for, and vertically below it lies the artery, in the gap between the scalenus anticus and iongus colli muscles. The procedure is sur- rounded with considerable difficulties. Air in veins. The veins of the neck are under the influence of the respiratory movements. The veins do not collapse owing^ to attachments to the surrounding fasciae. During inspiration these vessels become more or less emptied; during ex- piration they become enlarged and turgid. With greatly impeded breathing they may attain for- midable size. Since ether usually causes some respiratory difficulty, it is seldom administered in operations on the neck. The only other veins that are under the influence of the aspiratory power of the thorax are the axillary vein and its larger tributaries. When any one of these vessels is wounded, and the wound is for the moment dry, air may very readily be drawn into it during the inspirator^ act, just as air is drawn into the trachea. The air causes embolism of the pulmonary capillaries. Valves in the veins of the neck. The subclavinn veins and their tributaries are liberally pro- vided with valves, but the internal jugular has only one pair, situated at its termination in ix] CERVICAL SYMPATHETIC CORD 205 the innominate vein. There are no valves in the innominate veins or in the superior vena cava. When the venous pressure within the thorax is greatly raised, as in lifting heavy weights, only the terminal valves of the internal jugular vein prevent the transmission of the pressure to the brain. In accidents which cause sudden com- pression of the thorax, the head and neck may remain livid for days following the accident. The lividity is probably due to the jugular valves yielding, thus subjecting the capillaries of the head and neck to a higher pressure than they are able to withstand. Cervical part of the sympathetic cord, If, in the course of an operation on the neck, the sympathetic cord, which unites the superior, middle, and inferior cervical ganglia, should be cut or included in a ligature, a remarkable series of symptoms results, chiefly noted in the eye and orbit of the same side. It will be remembered that the nerve-fibres which supply the dilator muscle of the iris, the non-striated tarsal muscle of the upper lid, the non-striated muscle of the orbit, the sweat-glands of the face, and give vaso-motor branches to the arteries of the face, tongue, and neck, issue from the spinal cord by the anterior roots of the first and second dorsal nerves. They pass to the cervical cord in the white rami of these two nerves, ascending in the cord which lies behind the carotid sheath. The case of a woman in whom the sympathetic cord had been cut during the removal of tubercular glands from the right side of the neck is re- corded by Dr. Purves Stewart. "The right eyelid drooped a little, the right side of the face flushed less than the left; when she chewed, a small patch of excessive perspiration appeared below the right eye. The right pupil was smaller than the left, from paralysis of the dilator pupillje. Moreover, the affected pupil does not dilate when shaded, yet it contracts briskly to light and on convergence. . . . The cilio-spinal 206 THE HEAD AND NECK [CHAP. reflex is abolished; the pupil no longer dilates when the skin on the right side of the neck is pinched." The lymphatic glands of the head and iieck are numerous* and arranged in the follow- ing sets (Fig. 50) : (1) Submandibular glands, 10 to 15 in number, situated at the lower border of the jaw beneath the cervical fascia; (2) the suprahyoid, 1 or 2 in number, situated between the chin and hyoid bone near the middle line; (3) parotid or pre- auricular set, situated in and over the parotid gland; (4) postauricular or mastoid, 2 to 4 in number, situated over the mastoid process; (5) occipital, 3 to 5 in number, over the insertion of the complexus muscle; (6) superficial cervical glands, often absent, situated over the sterno- mastoid along the external jugular vein; (7) laryngeal, 1 to 3 in number, below the great horn of the hyoid ; (8) the upper deep cervical set, 10 to 20 in number, situated over the upper part of the internal jugular vein and bifurcation of the common carotid artery; (9) lower deep cervical set, surrounding the terminal parts of the in- ternal jugular, subclayian, external jugular, and transverse cervical veins. This set becomes con- tinuous with the axillary and mediastinal glands. These glands are very often enlarged and in- flamed, and it is in this part of the lymphatic system that tubercular enlargement of lymph- glands is most commonly met with. The inflam- matory affections in glands would appear to be always of a secondary nature, and to follow dis- turbances in those parts of the periphery whence they respectively receive their lymph. It may be convenient, therefore, to group the relations of certain glands to certain parts of the periphery. Scalp. Posterior part = occipital and post- auricular glands. Frontal and parietal portions = preauricular glands (Fig. 50). Vessels from the scalp also enter the super- ficial cervical set of glands. LYMPHATIC GLANDS 207 Fig. 50. Showing the positions of the lymphatic glands of the head and neck. The outlines of the sterno- mastoid (S.M.), trapezius (TR.), internal jugular, subclavian, and right innominate veins are shown. 1, Submandibular glands, 1' area drained ; 2, suprahyoid glands, 2' area drained ; 3, preauricular glands, 3' area drained ; 4, post- auricular glands, 4' area drained ; 5. occipital glands, 5' area drained ; 6, in front of external jugular vein, marking position of the superficial cervical glands ; 7, laryngeal gland ; 8, 8, 8, upper deep cervical glands ; 9, 9, 9, lower deep cervical glands : 10, gland receiving lymph from thyroid ; 11, superior mediastinal glands ; 12, axillary glands. 208 THE HEAD AND NEGK [CHAP. Skin of face and neck submandibular, piv- auricular, and superficial cervical glands. External ear = superficial cervical glands. Lower lip = submandibular and suprahyoid glands. Buccal cavity = submandibular glands and deep cervical glands (upper set). Gums of lower jaw - submandibular glands. Tongue. Anterior portion = suprahyoid and submandibular glands. Posterior portion = deep cervical glands (upper set). Tonsils and palate = deep cervical glands (upper set). Pharynx. Upper part = preauricular and retropharyngeal glands. Lower part = deep cervical glands (upper set). Larynx, orbit, and roof of mouth = deep cer- vical glands (upper set). Nasal fosscR retropharyngeal glands, deep cervical glands (upper set). Some lymphatics from the posterior part of the fossae enter the preauricular glands.* In the removal of the deep cervical glands a number of structures are liable to be wounded. The glands frequently become firmly adherent to the internal jugular vein; the uppermost glands surround the spinal accessory nerve ; the super- ficial cervical nerves pass among those of the lower deep cervical set ; the thoracic duct has been wounded in removing glands from the left supra- clavicular fossa. Thoracic duct in the neck. A point taken on the upper border of the clavicle, 1 inch from its sternal end, will mark the angle between the internal jugular and subclavian veins at. or near which the thoracic duct ends. In 40 bodies in- vestigated by Messrs. F. G. Parsons and P. W. G. Sargent the duct was found to end in the ter- minal part of the internal jugular vein in 35 instances; in nearly half of these cases the ter- * From " Scrofula, ami its Gland Diseases," by Sir Frederick Treves. 1882. ix] BRANCHIAL FISTULA 209 minal part of the duct divided; it frequently has two orifices, and may have as many as four. At its termination the duct curves outwards over the scalenus anticus and phrenic nerve above its point of entrance where it is usually furnished with valves. Ligature of the duct is followed by no untoward symptoms, as a rule, a result which is due to the free anastomosis that exists between it and the lymphatics ^of the right side of the thorax and to communications with the azygos veins (Leaf). As the duct ascends behind the left common carotid and subclavian arteries to enter the neck, it lies in contact with the pleura and lung. On the right side the thoracic duct is represented by the right lymphatic trunk. The tributaries of these two main lymphatic channels are in free communication within the thorax. Branchial fistulas Certain congenital fis- tulas are sometimes met with in the neck, which are due to partial persistence of one of the branchial clefts. These clefts are placed in the foetus between the branchial arches. The arches are usually described as five in number. The first lays the foundation for the lower jaw and malleus. From the second are developed the styloid process, the stylo-hyoid ligament, and lesser cornu of the hyoid bone. From the third are formed the body and greater cornu of the hyoid bone, while the fourth and fifth take part in the formation of the cartilages and soft parts of the neck below the hyoid bone. The first cleft is between^ the first and second arches. "The cervical branchial fistulse appear as very fine canals opening into minute orifices in one or both sides of the fore part of the neck, and leading backwards and inwards or backwards and upwards towards the pharynx or oesophagus" (Paget). Their length is about li to 2 1 inches, and their diameter varies from that of a bristle to that of an ordinary probe. The orifice of a cervical fistula is usually situated just above the sterno-clavicular joint (Fig. 51), 210 THE HEAD AND NECK [CHAP. and represents the orifice of the cervical sinus, a depression or pocket formed during the development of the neck of the foetus, and serving as a common orifice for the branchial or visceral clefts in which the tonsil, thymus, Fig. 51. Showing the positions and connexions of various embryological remnants in the neck. A, Tonsil ; B, remnant of tonsillar sac (from second cleft recess) ; C, carotid body between external and internal carotid arteries ; D, stalk of thymus (third cleft) ; E, cervical sinus (united with second cleft recess on left side) ; F, cervical thymus ; o, com- mon carotid ; G', median part of thyroid and Etyro-ffloseal duct; H, infrahyoid part of median thyroid ; I, stalk of lateral thyroid from fourth cleft ; K K, thymus in thorax- ixj BRANCHIAL FISTULA 211 and lateral thyroids are developed. The fistula, as it ascends, passes towards the bifurcation of the common carotid, where it may come into communication with the carotid body (derived from the third cleft), or with the tonsillar recess (from the second cleft). It can be understood that only parts of these saccular structures and outgrowths may persist, such remnants forming the bases for cervical cysts. Certain dermoid cysts of the neck, and also certain polycystic congenital tumours, occurring as one form of "hydrocele of the neck/' also arise from these branchial remnants. At the orifice of the fistulse, or at the position where they usually occur, tags of skin containing cartilage may appear. They are termed supernumerary auricles, because they occupy the same relationship to the fistulse that the external ear does to the first visceral cleft. The ventricle of the larynx, as is normally the case in many apes, may become prolonged into a sac which passes through the thyro-hyoid mem- brane, thus forming a cervical air-cyst or sac in the laryngeal region of the neck. PART II. THE THORAX CHAPTER X THE CHEST AND ITS VISCERA THE THORACIC WALLS THE two sides of the chest are seldom sym- metrical, the circumference of the right side being usually the greater, a fact that is supposed to be explained by the unequal use of the upper limbs. In Pott's disease, involving the dorsal region, when the spine is much bent forwards the thorax becomes greatly deformed. Its antero- posterior diameter is increased, the sternum protrudes, and may even be bent by the bending of the spine, the ribs are crushed together, and the body may be so shortened that the lower ribs overlap the iliac crest. In pigeon=breast deformity the sternum and cartilages are rendered protuberant, so that the antero-posterior measurement of the chest is much increased, while a deep sulcus exists on either side along the line of junction of the ribs and their cartilages. It is by the sinking-in of the parietes along the costo-chondral junctions that the protuberance is produced. In children, and especially in rickety children, the thorax is very pliable and elastic, and if a constant impediment exists to the entrance of air, as, for example, from greatly enlarged tonsils, the thoracic walls may yield in time to the suction brought to bear 212 KYPHORTS AND SCOLIOSIS 213 upon them at each inspiration. The weakest part of the thorax is along the costo-choiidral line on either side, and it is here that the parietes yield most conspicuously in such cases. Deformities of the chest result from abnormal curvatures of the dorsal part of the spinal column. The ribs are firmly bound to the verte- brae by the costo-vertebral and costo-transverse ligaments, and hence alteration in the position of vertebrae is attended by changes in the costal series. Thus, when there is kyphosis in the dorsal region the upper part of the spine is bent for- wards and down- wards, carrying with it the upper ribs and the sternum. The antero - posterior diameter of the thorax is thereby increased, but its vertical and mea " Fig. 52. -Showing the changes in the thorax which follow scoliosis of the spine. (After Redard.} The convexity of the spinal curvature is towards the right : on that side the ribs are sharply bent at their angles. On the concave (left) side the ribs have an open angle. transverse snrements decreased. When lateral curvature is produced in the dorsal re- gion, the ribs, on the side towards which the bend occurs, are necessarily compressed, while on the opposite side they are separated. In scoliosis of the spine not only is a lateral curvature formed, but the vertebrae undergo a rotation at the same time. The vertebral bodies move towards the convex side of the column, and their spinous processes towards the con- cavity of the curvature (Fig. 52). The ribs on the concave side are carried forwards on the trans- verse processes and their angles open^out, the side of the chest becoming flattened behind. On the other side (convex) the angles are unduly promi- 214 THE THORAX [CHAP. nent, for the ribs are carried backwards at their vertebral extremities and bent inwards in front. The transverse diameter of the chest thus becomes oblique (Fig. 52). On the concave side the inter- costal spaces are diminished in size, the ribs even coming into contact, while on the convex side the spaces are increased in size. The thoracic viscera are necessarily distorted in shape and altered in position. The sternum. The upper edge of the sternum corresponds to the disc between the second and third dorsal vertebrae, and the xiphisternal joint to the middle of the tenth dorsal. In the foetus at full term the upper edge of the sternum is opposite the middle of the first dorsal vertebra (Symington). A transverse ridge or angle may be felt upon its anterior surface that corresponds to the junction of the manubrium and body, and is in a line with the second costal cartilages. The bone is rarely fractured, being soft and spongy, and supported by the elastic ribs and their cartil- ages, as by a series of springs. In the old, when the cartilages are ossified and the chest is more rigid, the tendency to fracture is increased. The sternum is most of ten found fractured in connexion with injuries to the spine, although it may be broken by simple direct violence. The bone may be fractured by violent bending of the spine back- wards, and by abrupt bending of it forwards. In the former instance the lesion is probably due to muscular violence to the abdominal muscles and the sterno-mastoid pulling one against the other. In the latter instance the lesion is commonly brought about by the violent contact of the chin with the bone. Dislocation may occur at the sterno-manubrial joint (sternal synchondrosis). The manubrium in these injuries generally re- mains in situ, while the body with the ribs is displaced forwards in front of it. A consider- able degree of respiratory movement takes place at the sternal synchondrosis; only in very old people does it become obliterated by bony union. X] STERNUM AND RIBS 215 It possesses a distinct synovial cavity sur- rounded by strong fibrous and fibro-cartilagin- ous ligaments. Malgaigne cites the case of a youth who, from constant bending at his work as a watchmaker, caused the second piece of the sternum to glide backwards behind the manu- brium. From its exposed position and cancellpus struc- ture, the sternum is liable to many affections, such as caries and gummatous periostitis. The com- parative softness of the bone is such that it has been penetrated by a knife in homicidal wounds. The shape and position of the bone have also been altered by pressure, as seen sometimes in artisans following employments requiring in- struments, etc., to be pressed against the chest. Certain holes may appear in the middle of the sternum, and through them mediastinal abscesses may escape, and surface abscesses pass deeply into the thorax. These holes result from imperfect union of the right and left sternal bars, out of which the sternum is formed. In the case reported by E. Groux, the bone was separated vertically into two parts. The gap could be opened by muscular effort and the heart exposed, covered only by the soft parts. The sternum has been trephined for mediastinal abscess, and for para- centesis in pericardial effusion, and it has been proposed also to ligature the innominate artery through a, trephine hole in the upper part of the bone. The upper part has been divided vertically, each half being turned forwards and outwards with the corresponding ribs in order to gain access to the structures in the superior mediastinum. The ribs are placed so obliquely that the an- terior end of one rib is on a level with the pos- terior end of a rib some way below it in numerical order. Thus the second rib in front corresponds to the fifth rib behind, and the insertion of the seventh to the tenth. If a horizontal line be drawn round the body at the level of the inferior 216 THE THORAX [CHAP. angle of the scapula, while the arms are at the side, the line would cut the sternum in front at the attachment of the sixth cartilage, would cut the fifth rib at the nipple line, and the ninth rib at the vertebral column. The second rib is indi- cated by the transverse ridge on the sternum already alluded to (angulus Ludovici). The lower border of the pectoralis major leads to the fifth rib, and the first visible serration of the serratus magnus corresponds to the sixth. The longest rib is the seventh, the shortest the first. The most oblique rib is the ninth. As the arm hangs by the side the lower angle of the scapula covers the seventh rib. The ribs are elastic and much curved, and, being attached by many ligaments behind to the column, and in front to the yielding cartilages, resist with the qualities possessed by a spring such injuries as tend to produce fracture. A rib may be fractured by indirect violence, as by a wheel passing over the body when lying prostrate on the back. In such a case the force tends to approxi- mate the two ends of the bone, and to increase its curve. When it breaks, therefore, it breaks at the summit of its principal curve, i.e. about the centre of the bone. The fragments fracture out- wards, and the pleura stands no risk of being penetrated. ^ When the rib is broken by direct violence, lesion occurs at the spot encountered by the force, the bone fractures inwards, the curve of the rib tends to be diminished rather than increased, and there is much risk of the fragments lacerating the pleura. The ribs most often broken are the sixth, seventh, and eighth, these being, under ordinary circum- stances, the most exposed. The rib least frequently fractured is the first, which lies under cover of the clavicle. In elderly people dying from phthisis the cartilage of the first rib is often found to be cal- cified and occasionally to be fractured. Indeed, in the majority of people over 45 the cartilage of the first rib is calcified and ossified to a x] BIBS AND INTERCOSTAL SPACES 217 greater or less degree, and there is no doubt that the elasticity and mobility of such ribs are impaired. In cases of emphysema, it has been proposed to divide or even excise the cartilages of the upper ribs in order to increase the re- spiratory capacity and mobility of the thorax. Fractures are more common in the elderly than in children, owing to the ossification of the cartilages that takes place in advancing life. When a rib is fractured, no shortening occurs, the bone being fixed both in front and behind, while vertical displacement is prevented by the attachments of the intercostal muscles. Thus no obvious de- formity is produced unless a number of consecu- tive ribs are the subjects of fracture. These bones have been broken by muscular violence, as during coughing, and in violent expulsive efforts such as are incident to labour. In such instances the ribs are probably weakened by atrophy or disease. In rickets changes take place at the point of junction of the ribs and cartilages which lead to bony elevations, producing, when the ribs on both sides are affected, the condition known as the "rickety rosary." The costo-chondral junctions at which these enlargements occur correspond to the epiphyseal lines of long bones lines at which growth in length takes place. The intercostal spaces are wider in front than behind, and between the upper than the lower ribs. The widest of the spaces is the third, then the^ second, then the first. The seventh, eighth, ninth, and tenth interspaces are very nar- row in front of the angles of the ribs. The first five spaces are wide enough to admit the whole breadth of the index finger. The spaces are widened in inspiration, narrowed in expiration, and can be increased in width by bending the body over to the opposite side. Pa.racentesis is usually performed in the sixth or seventh space, at a point midway between the sternum and the spine, or midway between the 218 THE THORAX [CHAP. anterior and posterior axillary lines. The seventh space can be readily identified by its relation- ship to the angle of the scapula; when the arm is by the side of the body this space is slightly over- lapped by the angle. If a lower space be selected there is danger of wounding the diaphragm, especially upon the right side. If the eighth or ninth space be selected the incision is made just externally to the line of tHe angle of the scapula. The trocar should be entered during inspiration, the space being widened thereby, and should be kept as near as possible to the lower border of the space, so as to avoid the intercostal vessels. Tap- ping of the chest through any space posterior to the angles of the ribs is not practicable, owing to the thick covering of muscles upon the thoracic wall in this place, and the fact that the inter- costal artery, having a more horizontal course than the corresponding ribs, crosses the middle of this part of the space obliquely. Beyond the angle the intercostal vessels lie in a groove on the inferior border of the rib forming the upper boundary of the space. The vein lies immediately above the artery, and the nerve immediately below it. In the upper four or five spaces, however, the nerve is at first higher than the artery. Paracen- tesis of the thorax is occasionally followed by syn- cope or even death. It is difficult t9 account for such a result; it may be a reflex inhibition of the heart set up during perforation of the parietal pleura, which is richly supplied by the intercostal nerves, or by injury to the lung, which is supplied by the vagus. Pus may readily be conducted along the loose tissue between the two layers of intercostal mus- cles. Thus, in suppuration following upon disease of the vertebrae, or of the posterior parts of the ribs, the pus may be conducted along the inter- costal spaces to the sternum, and may thus pre- sent at a considerable distance from the real seat of the disease. Removal of ribs. In order to obtain a free xj THE FEMALE BREAST 219 opening into the pleural cavity a portion of one or even of two ribs may be excised. In some cases of long-standing empyema with an open sinus, all that part of the bony wall of the thorax which corresponds to the outer boundary of the suppurating cavity is removed in order that the cavity may collapse and be in a position to close. This latter measure is known as Estlander's operation, or thoracoplasty. In some instances portions of as many as nine ribs have been ex- cised, and the total length of bone removed has reached 50 to 60 inches. In removing a rib the bone is entirely bared of periosteum with the rugine, and the excision is extraperiosteal. In this way the intercostal vessels are not exposed, and, if divided subse- quently, can be readily secured when the ribs are out of the way. The internal mammary artery runs paral- lel to the border of the sternum, and about ^ an inch from it. It may give rise to rapidly fatal haemorrhage if wounded. The vessel may readily be secured in the first three intercostal spaces, and with some difficulty in the fourth or fifth space. It is most easily reached through the second space, and cannot be secured through any space below the fifth. The female breast extends from the second rib above to the sixth below, and from the side of the sternum to the midaxillary line (Stiles). In cases of retained lactation the twelve to fifteen irregular lobes which make up the body of the gland can be felt radiating outwards from the nipple. The lactiferous ducts, which correspond in number to the lobes, open at the apex of the nipple, within which each shows a dilatation or ampulla. Branching processes of adjoining lobes unite and enclose spaces within the body of the gland, containing connective tissue and masses of fat. After the menopause, when the glandular tissue is absorbed in great part, and during the resting condition, fat forms the greater part of 220 THE THORAX [CHAP. the female breast. Besides the main body of the gland, Stiles has drawn attention to numerous peripheral processes which lie in the surrounding connective tissue. Although the principal part of the breast rests on the pectoralis major, quite one-third of the gland crosses the outer border and rests on the serratus magnus within the axilla (Fig. 53). It also covers the origins of the obliquus abdominis externus and rectus abdominis. In excision or inflammation of the breast it is important to bind the arm by the side to keep the parts from being disturbed by the pectoralis major. Peripheral processes of the gland and many of its deep lymphatics enter the pectoral sheath, hence the removal of this structure with part, or even all, of the pectoral musculature if complete extirpation of cancer is to be assured. The loose retromammary tissue which binds the mamma loosely to the pectoral sheath may be the seat of abscess, or sometimes of a bursal cyst. The nipple, in the male and in the virgin female, is situated on the fourth intercostal space, about | of an inch from the junction of the ribs with their cartilages ; after lactation the breast becomes pendent, and the nipple no longer serves as a guide to the intercostal spaces. The nipple contains erectile and muscular tissue, and is richly supplied by cutaneous branches of the third and fourth spinal nerves. It is also furnished with a rich network of lymphatic vessels, which, when the breast is the site of cancer, may become invaded and blocked with cancerous epithelium, giving rise to the condition known as Paget's disease of the nipple (Handley). The skin is pigmented, thin, and sensitive, and often the seat of painful fissures and excoriations. In painful diseases of the breast, tender areas occur over the fourth and fifth spinal segments (Fig. 79, p. 359) (Head). The breast is developed by a solid invagination of epiblast at the point afterwards marked by xj LYMPHATICS OF THE BREAST 221 the nipple. About the sixth month of foetal lil'r the primitive mammary bud branches out in all directions within the subcutaneous tissue. Thus it comes about that the subcutaneous fascia is con- densed around the gland, forming its capsule. The retromammary part of the capsule is connected at the interlobular spaces with the superficial layer, which in turn is fixed to the skin by subcutaneous bands, or skin ligaments. It is through lymph channels that cancer spreads, and those of the breast, which is one of the commonest sites of cancer, are of especial im- portance if complete eradication of the disease is to be obtained. The lymph-vessels are arranged in the following sets: (1) Perilobular, round the acini and lobules ; (2) periductal, round the lac- tiferous ducts ; (3) interlobar, situated in the interlobar septa and joining (4) the retromam- mary network with (5) the superficial mammary in the anterior part of the capsule. If the inter- lobar septa are invaded by cancer they contract, and through their cutaneous attachments cause depressions in the skin; if the process invades the periductal vessels, the nipple is retracted. The mammary lymphatic system is connected with the subcutaneous network of vessels, to which cancer may spread, producing that variety of the disease known as cancer en cuirasse. Through communi- cations with the lymph channels of the pectoral fascia and muscle, cancer of the breast may spread to these structures. The gland then becomes firmly fixed to the deeply seated structures. The majority of the lymph- vessels pass from the breast fcp the pectoral alands, six to eight in number, situated along the anterior border of the axilla, and to the central axillary set, twelve to fifteen in number, situated beneath the axillary tuft of hair and on the inner side of the axillary vein (Fig. 53). From these two sets the lymph-vessels pass to the deep axillary glands lying along the front and inner side of the axillary vessels. The deep axil- lary glands become continuous with the lower deep 222 THE THORAX [CHAP. cervical glands. It is mainly along this path that cancer tends to spread, but vessels leave the inner segment of the breast and pass to the anterior intercostal glands situated in the upper four intercostal spaces and lying on each side of the internal mammary vessels, while occasionally a AXILLARY SET AXILLARY ST \ OE.EP CERVICAL SET CENTRAL SET AX'LLARY LOBE PECTORAL ST Fig. 53. Lymphatic vessels and glands of the breast and axilla. (Modified from Poirifir.) few vessels pass to the cephalic gland situated in the hiatus between the deltoid and pectoralis major muscles. Handley found a marked ten- dency for breast cancer to spread downwards in the lymphatics, passing to the epigastric triangle. There the vessels perforate the belly wall to join lymphatics both above and below the diaphragm ; it x] ARTERIES SUPPLYING THE MAMMA 223 is probably owing to this communication that the liver is so often the seat of secondary deposit in cases of cancer of the breast. When the normal channels become clogged with cancerous invasion, the lymph passes by circuitous paths. The sub- scapular glands, surrounding the subscapular vessels on the posterior wall of the axilla, may become infiltrated; through the lymphatics of the arm, which end in the central axillary glands, the structures round the shoulder may become the seats of secondary deposit; and through the com- munication between the lymph system of one breast with that of the other, across the sternum, a secondary deposit may even occur in the oppo- site breast (Stiles). The intercosto-humeral nerve pierces the cen- tral set of axillary glands. It becomes compressed when these glands are invaded by cancer, and pain is referred to the termination* of the nerve over the posterior aspect of the arm above the elbow. Various parts of the brachial plexus may also become involved, or the axillary vein or lymphatics occluded, the arm being swollen and cedematous in consequence. The following groups of arteries supply the gland and are cut in excision of the organ : (1) the lateral (long) thoracic, alar thoracic, thoracic branches of the acromio-thoracic axis ; (2) anterior perforating branches from the internal mammary at the second, third, and fourth intercostal spaces ; (3) lateral branches from the second, third, and fourth intercostal arteries. Supernumerary nipples and breasts may occur. They are commonly found in a line between the axilla and the groin. In the embryonic stage of all mammals an epiblastic mammary ridge is found in this position. In man it disappears except at one point, but occasionally some isolated part may persist and proceed to form a breast Embryology fails to explain the occurrence of breasts on the buttock or back, where they are occasionally found. 224 THE THORAX [CHAP. THE THOKACIC VISCERA Tlie lung. The apex of the lung rises in the neck from 1 to 2 inches above the inner half of the clavicle. Its highest point in the majority of adults lies li inches above the sternal end of the clavicle, in the interval between the sternal and clavicular heads of the sterno-mastoid muscle Fig. 54. Showing surface markings for the lungs and pleura. (Fig. 54). The anterior edges of the two lungs pass behind the sterno-clavicular articulations, and meet in the middle line at the sternal synchondrosis. The edge of the right lung then continues vertically downwards behind the middle line of the sternum to the sixth chondro-sternal articulation, where it slopes off along the lino of the sixth cartilage. The edge of the left lung keeps close to that of the right as far as xj THE LUNGS 225 the fourth chondro-sternal articulation, where it turns off to the left, following a line drawn from the fourth cartilage to near the apex of the heart (Fig. 54). Occasionally it does not diverge, but completely covers the pericardium up to the edge of the sternum. In the child, owing to the thymus, the lungs are more separated in front. The right reaches the middle line, but the left only reaches the left edge of the sternum (Symington). The easiest and also the most accurate method of indicating the lower border of the lung is the fol- lowing (Fig. 54) : A line is drawn along the sixth costal cartilage from its sternal end to its heel; from the heel the line is carried horizontally round the body; it will be found to cross the median line behind, at, or near the eleventh dorsal spine (the anticlinal spine). The corresponding border of the pleura is not parallel to the lower border of the lung ; it is indicated by a line drawn along the seventh costal cartilage from its sternal end to its heel ; from there the line is continued to a point 2 inches above the lowest part of the subcostal margin and then prolonged horizontally to the median line behind where it crosses at or near the twelfth dorsal spine. Between the pul- monary line above and the pleural line below, the diaphragm is in contact with the chest wall, separ- ated only by the costo-phrenic reflection of the pleura. On the left side these lines commence at a variable distance from the sternum 1 inch should be allowed for the pleura ; 2| inches for the lung (Fig. 54). The pleura is in relation with the twelfth rib, but occasionally it descends \ an inch or more below the neck of this rib, and may be wounded in operations on the kidney (Fig. 102, p. 453). It extends lower down in the child than in the adult. The left lung descends to a slightly lower level than the right. In penetrating: wounds involving the pleura, air may enter the pleural cavity, producing pneumothorax, and this air may be subsequently pressed by the respiratory movements into the 226 THE THORAX [CHAP. subcutaneous tissues through the wound in the ?arietal pleura, and lead to surgical emphysema, n injuries of the lung without external wound, as when that organ is torn by a fractured rib, the air escapes from the lung into the pleura, and may thence pass into the subcutaneous tissues through the pleural wound, thus producing both pneumothorax and emphysema. Modern bullets of high velocity penetrate the lung without giving rise to a great degree of damage to the pulmonary tissues, or causing much haemorrhage into the pleural space (hsemothorax). This result is due to the fact that the lungs contain air which is compressible, and lie inside an elastic-walled cavity. The same bullet, entering the medullary cavity of a bone, or the skull, causes an explosive effect because the marrow or brain is incompressible and locked up within a closed chamber. It is well to note that emphysema may occur about certain non-penetrating wounds of the thorax when they are of a valvular nature. In such cases the air is drawn into the subcutaneous tissues during one respiratory movement, and is forced by another into the cellular tissue, the valv- ular nature of the wound preventing its escape externally. Rupture of an air-vesicle of the lung during violent muscular effort, as in childbirth, may give rise to extensive emphysema of the thorax and neck. When the pleural "cavity" is opened, the lungs, owing to the amount of elastic tissue they contain, undergo some degree of collapse, but there is much misconception regarding the extent to which this takes place. Half the air in the lung, in some cases even two-thirds, is residual and cannot be expelled by the passive collapse of the lung; when the diaphragm is pushed up and the ribs are pulled down by the expiratory efforts of the muscles of the belly-wall the thoracic space may be so reduced in size that the lung still more than fills it; if the glottis be closed a hernia of the lung will occur through the wound in the chest xj WOUNDS OF PLEURA AND LUNG 227 wall. If, however, there is a valvular orifice into the pleural cavity, so that air can be sucked in but not expelled from it, every respiratory effort increases the amount of air in the pleural space; then compression of the lung and suffo- cation quickly ensue. Air or fluid introduced within the healthy pleural cavity is rapidly absorbed. Air is much more quickly absorbed by the pleura than is a pleural effusion or blood. Hence the practice of replacing the blood or fluid, as it is being withdrawn, by an equal volume of purified air. As the air is absorbed the lung tends to expand to fill the vacuum created. Macewen is of opinion that collapse of the lung is prevented by the capillary attraction which exists between the visceral and parietal layers of the pleura. In wounds of the lung the blood may escape in three directions : into the tissue of the organ (pulmonary apoplexy), into the bronchi (causing haemoptysis), and into the pleura, (causing hsemo- thorax). In some instances the lung has been ruptured without wound and without fracture to the ribs. Owing to the fineness of its capillaries, and to the fact that all venous blood returned to the heart must pass through the lungs before it can reach other parts of the body, it follows that pysemic and other secondary deposits are more commonly met with in the lung than in any o.ther of the viscera. Lung cavities resulting from tuberculosis, gan- grene, or bronchiectasis have been successfully incised and drained, and the same measure has been applied to hydatid cvsts of the lung. Deep incisions in the lung are followed by less haemor- rhage than might be expected from such a vas- cular organ. In tuberculosis of the lungs pleural adhesions are soon formed, and the lung is thus firmly bound to the chest-wall. In order that the part of the lung which is the site of a large cavity may be allowed to collapse, thus obliterating 228 THE THORAX [CHAP. the cavity and permitting it to heal, the prac- tice of opening the thoracic wall and breaking down the adhesions has been recently introduced. It is too soon to form an estimate of the results of this daring measure. Nerve supply of the pleura. In acute inflam- mation of the pleura, pain may be very intense, and the respiratory movements on the side affected may be greatly diminished. The pain, if in the lower part of the thorax, may be referred to the abdomen. The explanation of these facts must be sought in the nerve supply of the pleura. The costal pleura is supplied *by the adjacent inter- costal nerves, which also supply the corresponding intercostal muscles. The muscles are inhibited when the underlying parts of the pleura are in- flamed. The lower six dorsal nerves also supply the abdominal wall ; hence pain arising in the costal pleura may be referred by the patient to the abdomen, and lead to a suspicion of abdominal disease. The diaphragmatic and the mediastinal pleura are supplied by the phrenic nerves, and pain arising in these parts may be referred to the neck or shoulder. The cervical pleura is also supplied by the phrenic nerve (H. M. Johnston). The tracliesi divides opposite the junction of the sternal synchondrosis in front, and the fourth dorsal vertebra behind. In the fork of the bronchi, and accompanying the bronchi into the roots of the lungs, are chains of lymphatic glands. These become enlarged in all inflam- matory conditions of the lungs, giving rise to opacities in radiograms of the thorax and to a dullness on percussion on each side of the upper five dorsal vertebrae (Clive Riviere). The presence of foreign bodies in the air- passages has already been considered (p. 195) ; but it may here be pointed out that in some cases they have shown a remarkable facility for escaping through the parietes. Thus, Sir Rickman Grodlce records the case of a child, from an abscess in whose back there escaped a head of rye-grass x] THE PERICARDIUM 22 that had found its way into the air-passages forty-three days previously. Foreign bodies in the trachea and bronchi can now be located and extracted by aid of the bronchoscope. The mucous membrane at the bi- furcation of the trachea is highly sensitive, and the orifices of the secondary bronchial tubes can be seen to contract and dilate by virtue of the circular musculature in their walls. The root of the lung and bronchi can be ex- posed by opening the dorsal wall of the thorax behind the vertebral border of the scapula. Rus- sell and Fox record the case of a boy in whom a pin, 3 inches long, had slipped head downwards within the trachea, and ultimately lodged in the lower division of the left bronchus. They resected part of the eighth rib from the back, pushed the lung forwards to expose the bronchus at the root, and removed the pin. The root of the lung re- quires to be steadied; through the pericardium it is intimately bound to the diaphragm and follows the movements of that muscle. In the case men- tioned above, the boy was able to leave the hospital twelve days after the operation. The heart and pericardium. The position and extent of the pericardium may be indicated thus on the surface of the thorax (Fig. 55) : Three points are taken : (1) the apical, over the apex beat, in the fifth left intercostal space, 3i inches from the sternum; (2) the sterno-manubrial, mid- way between the insertions of the second costal cartilages; (3) the inferior caval, 1 inch to the right of the sterno-ensiform (sterno-xiphoid) point and directly superficial to the termination of the in- ferior vena cava. When these three points are united by curved lines, as in Fig. 55, the area over the pericardium and its contents is marked out. The lower line crosses \ an inch or more below the sterno-ensiform point; if a trocar be thrust back- wards in the angle between the ensiform process and seventh left costal cartilage, it enters the pericardium just above the diaphragm. Through 230 THE THORAX [CHAP. this angle the pericardium may be drained ; by resecting part of the fifth and sixth cartilages its cavity may be explored. The right border of the pericardium is deeply placed and covered by the right lung (Fig. 54) ; in health it should not project more than 1 inch beyond the right sternal border. Besides the auricles and ventricles the follow- RIC.HT IMT. JUGULAR VE RiCHT 5UBCLAV! l/t /ion. Vein ARCM OP AORTA Ry ART. Fig. 55. Relationship of the pericardium and heart to the sternum and ribs. ing parts are contained in the pericardium : The terminations of the inferior and superior venae cavse ; the ascending aorta and pulmonary artery. The position of these parts, and of the arch of the aorta and its branches, is shown in Fig. 55. It will be observed that more than two-thirds of the anterior surface of the heart is made up of right ventricle and auricle; consequently it is these x] WOUNDS OF THE HEART 231 parts which are usually perforated in stabs of the heart. The heart may be exposed for operative treat- ment by removal of the terminal inch or more of the fourth and fifth left costal cartilages. The heart may be freely handled and sutured; the surgeon's task is rendered difficult by its rapid motions and the respiratory movements of the pericardium and diaphragm. When the heart is wounded, blood escapes into the pericardium, lead- ing to compression of the auricles and the arrest of the inflow of blood. Hydrops of the pericardium may cause death in a similar manner. Other things being equal, a wound of the ventricle is less rapidly fatal than is a wound of the auricle, owing to the thickness of the ventricular wall, and to its capacity for contracting and preventing the escape of blood. Many instances have been recorded to show that the heart may be very tolerant of foreign bodies in its substance. Thus a man lived for twenty^ days with a skewer traversing the heart from side to side (Ferrus). In another case a lunatic pushed an iron rod, over 6 inches in length, into his chest, until it disappeared from view, although it could be felt beneath the skin receiving pulsation from the heart. He died a year following, and the metal was found to have pierced not only the lungs but also the ventricular cavities (Tillaux). The heart, too, is tolerant of foreign bodies lying within its chambers. During the Great War a considerable number of soldiers were observed to have a bullet or fragment lying free within the right ventricle, and yet, in such cases, no wound could be found anywhere in the wall of the heart. The bullet in such cases finds its way into one of the great veins, and is swept with the venous blood to the right chambers. In no case had the foreign body been carried into the pulmonary artery. Wounds of the heart have been sutured, the in- sertion of the stitches causing only momentary disturbance of its action. Travers has sutured 232 THE THORAX [CHAP. a wound of the right ventricle into which he was able to place three fingers to prevent haemor- rhage. Apropos of chest wounds, Velpeau cites the case of a man in whose thorax was found a part of a foil that entirely transfixed the chest from ribs to spine, and that had been introduced fifteen years before death. In the museum of the Royal College of Surgeons is the shaft of a cart that had been forced through the ribs on the left side, had passed entirely through the chest, and had come out through the ribs on the right side. The patient had lived ten years. Paracentesis of the pericardium As already mentioned, the pericardium may be tapped or drained through the left cqsto-ensiform angle (Fig. 55). The extent to which it is covered by the left pleura and lung is extremely variable, but in the majority of cases it may be tapped in the left fourth and fifth spaces, as far as 1 inch from the sternum, without injuring the pleura. The internal mammary artery descends in these spaces ^ an inch from the sternum, and divides, behind the seventh cartilage, into its superior epigastric and musculo-phrenic branches. The mediastina. Abscess in the anterior mediastinum may have developed in situ, or may have spread down from the neck. In like manner posterior mediastinal abscesses may arise from diseases of the adjacent spine, or lymphatic glands, or may be due to the spreading down- wards of a retropharyngeal or retro-cesophageal collection of matter. The employment of Rontgen rays in the diag- nosis of intrathoracic disease has greatly enlarged our knowledge of the respiratory movements and relationships of the thoracic viscera. In Fig. 56 (from a careful drawing given by Dr. Halls Dally) a representation is given of the more important parts seen when the chest is examined in an axis passing from the right nipple to the left scapula of the patient. The heart and liver appear as shadows, moving downwards and x] MOVEMENTS OF THORACIC VISCERA 233 forwards in inspiration, upwards and backwards in expiration. As the diaphragm descends, and the heart moves away from the spine, the pos- terior mediastinum, containing the aorta and oesophagus, appears as a transradiant triangle. With inspiration, too, the lungs clear up and become more transparent. The anterior medias- tinum also is seen as a clear space. In the superior mediastinum may be seen the arch of the aorta as it passes backwards from the manu- DlAPH. IN EXPIRAT DlAPH. IN INSPIRAT. AORTIC ARCH ANT. MEDIASTINUM STERNUM HEART LIVER TRANSLUCENT TRIANGLE Fig. 56. Orthodiagram of the thorax. (After Dr. Halls Dally.) The position of parts is shown in extreme inspiration ; the position of the diaphragm and liver in expiration is also shown. brium to the fourth dorsal vertebra. In the in- dividual from whom the diagram was constructed the vertical movement of the diaphragm amounted to 3 inches. In normal respiration the vertical movement varies from to } of an inch, equal to a movement of a rib-breadth. The azygos veins, commencing as they do below in the lumbar veins, and having more or less direct communications with the common iliac, renal, and other tributaries to the vena cava, are able to a great extent to carry on the venous circula- 234 THE THORAX [CHAP. tion in cases^ of obstruction of the terminal part of the superior vena cava. In this they are as- sisted by the venae comites of the internal mam- mary artery and epigastric veins; the intraverte- bral veins also become greatly enlarged, and serve as anastomotic channels between the superior and inferior caval systems. These veins are apt to be pressed upon by tumours (such as enlarged gland masses) de- veloped in the posterior mediastinum, and to pro- duce in consequence some oedema of the chest walls by engorgement of those intercostal veins which they receive. Tumours growing in the pos- terior mediastinum may cause trouble by press- ing upon the trachea or gullet, or by disturbing the vagus nerve or the cord of the sympathetic. The numerous lymphatic glands which surround the trachea, bronchi, and oesophagus are often the seat of tuberculosis. They become adherent to these organs and may ulcerate into them. In the obscure condition named status lymplia- ticus the thymus gland is usually found greatly enlarged. It occupies the anterior mediastinum, being placed in front of the upper part of the pericardium and great vessels of the heart, and behind the part of the sternum and the costal car- tilages which lie above the level of the third pair of ribs. Its sides are covered by reflections of the mediastinal pleura. When enlarged, it presses on the great vessels and on the treachea and bronchi, causing a certain degree of obstruction, but not enough to account for sudden death in cases of status lymphaticus. The thymus gland, composed of lymphoid tissue, reaches its maximum size (36 grammes = 1| oz.) about the eighteenth year; thereafter it becomes gradually reduced in size more so in men than in women. In a child at birth it should weigh about 12 grm. Its arteries and veins, derived from the internal mammary, inferior thyroid, and innominate ves- sels, are of small size. The gland is attached by loose connective tissue to surrounding struc- x] THORACIC DUCT 235 tures. Its partial or even complete removal through a transverse incision made between the ends of the clavicles is feasible (p. 240). Its functions are obscure, but it has a direct effect on the development and growth of bone. For development, see Fig. 51, p. 210. Thoracic duel. Krabbel reports a case of fracture of the ninth dorsal vertebra associated with rupture of the thoracic duct. The patient died in a few days, and the right pleura was found to contain more than a gallon of pure chyle. The bodies of the upper lumbar and lower dorsal vertebrae are frequently the site of tuber- culosis ; so are the apical parts of the lungs. Prof. Wood- Jones has drawn attention to the close relationship of these parts to the thoracic duct, and to the possibility of a tubercular invasion from the alimentary canal being conveyed to these sites of election by the duct. The recepta- culum chyli is formed on the bodies of the first and second lumbar vertebrae, from which the duct ascends in the posterior mediastinum in front of the lower dorsal vertebrae. In cases of cancer of the stomach, the cervical glands round the termination of the thoracic duct may become enlarged by secondary growths at an early stage of the disease. The secondary dissemination takes place by means of the thoracic duct. PART III.-THE UPPER EXTREMITY CHAPTER XI THE REGION OF THE SHOULDER A STUDY of the region of the shoulder comprises the clavicle, the scapula, the upper end of the humerus, and the soft parts that surround them, together with the shoulder- joint and axilla. Surface anatomy* The clavicle, acromion process, and scapular spine are all subcutaneous, and can be readily felt. In the upright position, when the arm hangs by the side, the clavicle is, as a rule, not quite horizontal. In well-developed subjects it inclines a little upwards at its outer end.* In the recumbent posture, the weight of the limb being taken off, the outer end rises still higher above the sternal extremity. The degree of the elevation can be best estimated by a study of frozen sections. Thus, in making horizontal sections of the body, layer by layer, from above downwards, Braune found ^hat by the time the sterno-clavicular articulation was reached, the head of the humerus would be cut across in the lateral part of the section (Fig. 57) % The deltoid tubercle of the clavicle may, if large, be felt through the skin, and be mistaken for an exostosis. The acromio : clavicular joint lies in fche plane of a vertical line passing up the middle of the front of the arm. A prominence is * In some women, in the feeble, and in some narrow-shouldered men the clavicle may be horizontal, or its outer end may incline downwards, 23C7 SURFACE OF THE SHOULDER 237 sometimes felt about this joint in place of the level surface that it should present. This is due to an enlargement of the end of the clavicle, or to a thickening of the nbro-cartilage sometimes found in the joint. In many cases it has ap- peared to be due to a trifling luxation upwards of the clavicle, depending upon some stretch- ing of the ligaments. It is certain that the dry bone seldom shows an enlargement such as to account for this very common prominence at the acromial articulation. The sternal end of the clavicle is also, in muscular subjects, often large and unduly prominent, and sufficiently conspicu- ous to suggest a lesion of the bone or joint when none exists. The roundness and prominence of the point of the shoulder depend upon the development of the deltoid and the position of the upper end of the humerus. The deltoid hangs like a curtain from the shoulder girdle, and is bulged out, as it were, by the bone that it covers. If the head of the humerus, therefore, be diminished in bulk, as in some impacted fractures about the anatomical neck, or be removed from the glenoid cavity, as in dislocations, the deltoid becomes more or less flat- tened, and the acromion proportionately promi- nent. The part of the humerus felt beneath the deltoid is not the head, but the tuberosities, the greater tuberosity externally, the lesser in front. A considerable portion of the head of the bone can be felt by the fingers placed high up in the axilla, the arm being forcibly abducted so as to bring the head in contact with the lower part of the capsule. The head of the humerus faces very much in the direction of the internal or medial epicondyle. As this relation, of course, holds good in every position of the bone, it is of value in examining injuries about the shoulder, and in reducing dislocations by manipulation, the epi- condyle being used as an index to the position of the upper end of the bone. In thin subjects the outline and borders of 238 THE UPPER EXTREMITY [CHAP. the scapula can be more or less distinctly made out, but in fat and muscular subjects all parts of the bone, except the spine and acromion, are difficult of access in the ordinary positions of the limb. To bring out the superior (medial) angle and vertebral border of the bone, the hand of the subject should be carried as far as possible over the opposite shoulder. To bring out the inferior angle and axillary border, the forearm should be placed behind the back. The angle formed at the point of junction of the spine of the scapula and the acromion is the best point from which to take measurement of the arm, the tape being carried down to the external condyle of the humerus. The upper border of the scapula lies on the second rib, its lower angle on the seventh. When the arm hangs at the side with the palm of the hand directed forwards, the acromion, external or lateral epicondyle, and styloid process of the radius all lie in the same line. The groove between the pectoralis major and deltoid muscles can usually be made out. In it run the cephalic vein and a large branch of the acromio-thoracic artery. Near the groove, and a little below the clavicle, the coracoid process may be felt. This process, however, does not actually present in the interval between the two muscles, but is covered by the innermost fibres of the deltoid. The position of the coraco-acromial ligament may be defined, and a knife thrust through the middle of it should strike the biceps tendon and open the shoulder-joint. When the arm hangs at the side with the palm forwards, the bicipital groove (intertubercular sulcus) may be defined directly below the acromio- clavicular joint. Just below the clavicle is a depression, the infraclavicular fossa, which varies considerably in depth in different subjects. It is obliterated in subcoracoid dislocations of the humerus, in frac- tures of the clavicle with displacement, by many axillary growths, and by some inflammations of xi] SURFACE OF THE AXILLA 239 the upper part of the thoracic wall. In sub- clavicular or infracoracoid dislocation the fossa is replaced by an eminence. In this region, at a spot to the inner (medial) side of the coracoid process, and corresponding nearly to the middle of the clavicle, the pulsations of the axillary artery can be felt against the second rib. Just below the clavicle the interspace between the sternal and clavicular portions of the pectoralis major can often be made out. The anterior and posterior borders of the axilla are very distinct. The anterior border, formed by the lower edge of the pectoralis major, follows the line of the fifth rib. The depression of the armpit varies, other things being equal, with the position of the upper limb. It is most deep when the arm is raised from the side at an angle of about 45, and when the muscles forming the bor- ders of the space are in a state of contraction. As the arm is raised above the horizontal line the depression becomes shallower, the head of the bone projecting into the space and more or less obliter- ating it, while the width of the fossa is encroached upon by the approximation of the anterior^ and posterior folds. The coracp-brachialis muscle itself forms a distinct projection along the humeral side of the axilla when the arm is raised to a right angle with the body. If the arm be brought nearly close to the side, the surgeon's hand can be thrust well up into the axilla, and the thoracic wall explored as high up as the third rib. The axillary glands cannot be felt when they are in a normal condition. The central set lies beneath the axillary tuft of hair. The direction of the axillary artery, when the arm is raised from the side, is represented by a line drawn from the middle of the clavicle to the humerus at the inner (medial) side of the coracp- brachialis. A line drawn from the third rib near its cartilage to the tip of the coracoid pro- cess indicates the upper border of the pectoralis minor, and the spot where this line crosses the 240 THE UPPER EXTREMITY [CHAP. line of the axillary artery points out the position of the acromio-thoracic artery. A line drawn from the fifth rib near its cartilage to the tip of the coracoid process indicates the lower border of the pectoralis minor, and the position of the lateral or long thoracic artery which runs along that border. The line of the subscapular artery corresponds to the lower or lateral border of the subscapularis muscle along which it runs, but the position of this border can only be ap- proximately indicated on the living or undissected subject. The circumflex (axillary) nerve and posterior circumflex artery cross the humerus in a hori- zontal line that is about a finger's breadth above the centre of the vertical axis of the deltoid muscle. This point is of importance in cases of supposed contusion of the nerve. These various indications of the positions of the main branches of the axillary artery are made while the arm hangs in its natural position at the side. The dor- salis scapulae artery (circumflex scapular) crosses the axillary border at a point corresponding to the centre of the vertical axis of the deltoid. The clavicle. The skin over the clavicle is loosely attached, and is easily displaced about the bone. This circumstance may serve to explain why the skin so often escapes actual wound in contusions of the clavicular region, and in part explains the infrequency of penetration of the integument in fractures of the clavicle. The three supraclavicular nerves that cross the clavicle are branches of the third and fourth cervical nerves, and it is well to note that pain over the collar-bone is sometimes a marked feature in disease of the upper cervical spine. This symp torn is then due to irritation of these nerves at their points of exit from the spinal canal. A communica- tion between the external jugular and cephalic veins is occasionally seen to cross the clavicle. Beneath the clavicle the great vessels and the great nerve-cords lie upon the first rib. The vein xi] THE CLAVICLE 241 is the most internal, and occupies the acute angle between the collar-bone and the first rib. It will be seen that growths from the bone may readily press upon these important structures, and that the vein, from its position, as well as from the slighter resistance that it offers, is likely to be the first to be compressed. These structures have also been wounded by fragments of bone in CLAVICLE STERNO MYOIO \ PHRENIC N, \\ LT CAftOT/0 ARTERY 1*7 fi IB. \ \\ \LTINNOM.VEIN l_TSUBCLAV.VEIN\ \ \\\ \9rf**O-TMYfHH PCCTORALIS MAJOR \ \ \\\\\ \MANUBR/UM fCCTOflALIS MINOR COKACO-BffACM/ALlS A BICEPS \ HZAOOFHUMERUS Fig. 57. Horizontal section at the level of the left shoulder-joint, to show the lie of the parts in the vicinity of the left clavicle. (After Bmune.) fracture of the clavicle. Fortunately, between the clavicle and these large nerves and vessels the subclavius muscle is interposed. This muscle is closely attached to the under surface of the bone, is enveloped in a dense fascia, and forms one of the chief protections to the ves- sels in case of fracture. This interposing p^ad of muscle is also of great service in resection operations. Behind the clavicle the following structures may be noted (Fig. 57), viz. the in- 242 THE UPPER EXTREMITY [CHAP. nominate, subclavian, and external jugular veins, the subclavian, suprascapular (transverse scapu- lar), and internal mammary arteries, the cords of the brachial plexus, the phrenic nerve and long thoracic nerve (nerve of Bell), the thoracic duct, the omo-hyoid, scalene, sterno-hyoid, and sterno-thyroid muscles, and the apex of the lung. The sternal end of the bone is not far removed from the innominate or left carotid artery, the vagus and recurrent nerves, the trachea, and the oesophagus. These relations of the clavicle are given to show the dangers in the way of partial or complete resections of the bone. The difficulties and risks of the operation increase as one progresses from the acromial to the sternal end. Resection of the acromial third of the bone is comparatively easy, but resection of the sternal portion is difficult and dangerous. The entire clavicle has been re- moved with success, and the operation has been followed by less impairment of the arm movements than would be imagined. The clavicle forms the sole direct bony con- nexion between the upper limb and the trunk, and in severe accidents, this connexion being broken through, it is possible for the extremity to be torn off entire. Thus Billrpth reports the case of a boy aged 14, whose right arm, with the scapula and clavicle, was so torn from the trunk by a machine accident that it was only attached by a strip of skin 2 inches wide. Other similar cases of avulsion of the limb have also been reported. Fractures of the clavicle. The clavicle is more frequently broken than is any other single bone in the body. This is due to the fact that it is the only bony connexion between the upper extremity and the trunk, and is often exposed to violence. Force can be brought to bear on it by means of a long lever, the upper extremity. The common fracture, that due to indirect violence, is oblique, and very constant in its position, viz. xi] FRACTURES OF THE CLAVICLE 243 at the outer end of the middle third of the bone. So closely is the outer third of the clavicle bound by ligaments to the coracoid and acromion pro- cesses that it may be regarded as part of the scapula. Hence the impact resulting from a fall on the shoulder is transferred to the clavicle at the junction of its outer and middle thirds. The bone breaks at the point where the force is trans- ferred to the clavicle from the scapula. The posi- tion of the coraco-clavicular ligaments is no doubt of the greatest import in localizing the fracture in this position, since a clavicle experimentally subjected to longitudinal compression does not break at this spot (Bennett). The displacement that occurs is as follows. The inner fragment remains unchanged in position, or its outer end is drawn a little upwards by the sterno-mastoid. It will be seen that any action of this muscle would be resisted by the pectoralis major and the costo-clavicular (rhomboid) liga- ment. The outer fragment undergoes a threefold displacement. (1) It is carried directly down- wards. This is effected mainly by the weight of the limb aided by the pectoralis minor, the lower fibres of the pectoralis major, and the latissimus dorsi. (2) It is carried directly in- wards by the muscles that pass from the trunk to the shoulder, viz. the levator scapulae, the latissimus dorsi, and especially by the pec- torals. (3) The fragment is rotated in such a way that the outer end projects forwards, the inner end backwards. This rotation is brought about mainly by the two pectorals, assisted pro- minently by the serratus magnus (anterior). The normal action of this latter muscle is to carry the scapula forwards, and the clavicle, acting as a kind of outrigger to keep the upper limb at a proper distance from the trunk, moves forwards at the same time and keeps the scapula direct. When this outrigger is broken the serratus can no longer carry the scapula directly forwards. The bone tends to turn towards the trunk, and the 244 THE UPPER EXTREMITY [CHAP. point of the shoulder is therefore seen to move inwards as well as forwards. The fragments in this fracture must consequently overlap, and as the displacement is difficult to remedy, it follows that in no bone save the femur is shortening so uniformly left as after an oblique fracture of the clavicle. The degree of shortening very seldom exceeds an inch. The deformity associated with this fracture is well corrected when the patient assumes the recumbent position. In this posture, the weight of the limb being taken off, the down- ward displacement is at once remedied. The point of the shoulder falling back also tends to relieve in part the inward displacement, and the rotation of the outer fragment forwards. It is through the scapula, however, that these two latter displacements are in the main removed. In the recumbent posture the scapula is pressed closely against the thorax, with the result that its outer extremity (and with it, of course, the outer frag- ment of the clavicle) is dragged outwards and backwards. Some surgeons, recognizing this im- portant action of the scapula in remedying the displacement in these cases, strap the scapula fi.rm.ly against the trunk, while at the same time they elevate the arm. Fractures due to direct violence are usually transverse, and may be at any part of the bone. When about the middle third they present the displacement just described. When the fracture is between the conoid and trapezoid ligaments no displacement is possible. When beyond these liga- ments, the outer end of the outer fragment is car- ried forwards by the pectorals and serratus, and its inner end is a little drawn up by the trapezius. In this fracture there is no general displacement downwards of the outer fragment, since it can- not move in that direction unless the scapula go with it, and the scapula remains fixed by the coraco-clavicular ligaments to the inner fragment of the clavicle. The clavicle may be broken by muscular vio- xi] FRACTURES OF THE CLAVICLE 245 lence alone. Polaillon, from a careful analysis of the reported cases, concludes that the muscles that break the bone are the deltoid and the clavicular Eart of the great pectoral. In no case does the racture appear to have been produced by the sterno-mastoid muscle. The commonest movements producing fracture appear to be violent move- ments of the limb forwards and inwards, or up- wards. These fractures are usually about the middle of the bone, and show no displacement other than that of both fragments forwards, i.e. in the direction of the fibres of the two muscles first named. The clavicle is more frequently the seat of green-stick fracture than is any other bone in the body ; indeed, one-half of the cases of broken collar-bone occur before the age of 5 years. A reference to the relations of the bone will show that important structures^ may be wounded in severe fractures associated with much displace- ment and with sharp fragments (see ^Fig. 57). Several cases are reported of paralysis of the upper limb (as a rule incomplete) following upon fracture of this bone. In some cases this symp- tom was due to actual compression or tearing of some of the great nerve-cords by the displaced fragments. In other cases the nerve injury, while due to the original accident, was yet independent of the broken clavicle. Paralysis of the biceps, brachialis, andbrachio-radialis (supinator longus), muscles supplied through the upper (lateral) cord, may result from heavy weights being carried on the shoulder (Fig. 85, p. 392). Cases are re- ported of wound of the subclavian artery, of the subclavian vein, of the internal jugular vein, and of the acromio-thoracic artery. In several instances the fracture has been associated with wound of the lung, with or without a fracture of the upper ribs. The clavicle begins to ossify before any bone in the bodv. At birth the entire shaft is bony, the two ends being still cartilaginous. There is one cpiphysis for its sternal end, which appears 246 THE UPPER EXTREMITY [CHAP. between the eighteenth and twentieth years, and joins the shaft about 25. It is a mere shell, is closely surrounded by the ligaments of the sternal joint, and cannot, therefore, be well separated by accident.* In cases where the clavicle is described as congenitally absent, the membrane-formed part of the bone is represented by a ligamentous cord; the cartilage-formed extremities are repre- sented by bony nodules. Defective ossification of the clavicle is commonly associated with an imperfect ossification of the membrane-formed bones of the skull, the condition being known as cranio-cleido-dysostosis, a disease of which D. Fitzwilliams has collected 60 examples. The subjects of this disease, owing to the ligamentous condition of the greater part of the clavicle, are able to approximate their shoulder to a remarkable ^extent. The defect in the clavicle may be so limited as to resemble a fracture. ^ Sterno-claviciilar joint. Although this is the only articulation that directly connects the upper limb with the trunk, yet it is possessed of such considerable strength that luxation at the joint is comparatively rare. The amount of move- ment in the joint depends to a great extent upon the lack of adaptability between the facets on the sternum and the sternal end of the clavicle. ^The disproportion between these parts is maintained by the interarticular cartilage, which reproduces only the outline of the clavicular surface. The cavity of the joint is V-shaped, since the clavicle only touches the socket at its inferior angle when the arm hangs by the side. When the arm is elevated, however, the two bones are brought in more immediate contact, and the joint cavity be- comes a mere slit. Thus, in disease of this articu- lation it will be found that of all movements of the joint the movement of the limb upwards is * Mr. Heath (Lancet, Nov. 18, 1882) reports a case which is probably unique. It concerns a lad aged 14, who, in the act of bowling at cricket, tore the clavicle away from its epiphyseal cartilage, which re-mained in situ. The muscle producing the accident was apparently the pectoralis major. xi] STERNO-OLAVICULAR JOINT 247 the most constant in producing pain. The joint is supplied by the suprasternal branch of the descending cervical nerves. The movements permitted at this joint are limited, owing to the anterior and posterior sterno-clavicular ligaments being moderately tense in all positions of the clavicle. Movement forwards of the clavicle on the sternum is checked by the posterior ligament, and resisted by the an- terior ligament. This latter ligament is more lax and less substantial than is the posterior band. Its weakness serves in part to explain the fre- quency of the dislocation forwards. Movement of the clavicle backwards on the sternum is checked by the anterior ligament, while the passage of the head of the bone is resisted by the powerful posterior band. The movement is also opposed by the costo-clavicular ligament. To produce, therefore, a dislocation backwards considerable force must be used. Disease of the sterno=clavicular joint. This articulation is really divided into two joints by the interarticular cartilage, each being provided with a distinct synovial membrane. These joints are liable to the ordinary maladies of joints, and it would appear that the disease may commence in, and be for some time limited to, only one of the synovial sacs. In time the whole articulation usually becomes involved, but even in advanced cases the mischief is sometimes restricted to the synovial cavity on one side of the cartilage. According to some authors, this joint is more frequently involved in pyaemia than is any other. When effusion has taken place into the sterno-clavicular joint, and especially after sup- puration has ensued, the swelling usually makes itself evident in front, owing to the fact that the anterior sterno-clavicular ligament is the thinnest and least resisting of the ligamentous structures about the articulation. For the same reason the pus usually escapes from the anterior surface when it discharges itself spontaneously. 248 THE UPPER EXTREMITY [CHAP. Dislocations of the sterno-clavicular joint The clavicle may be dislocated from the sternum in one of three directions, which, given in order of frequency, are : (1) forwards, (2) backwards, (3) upwards. The relative frequency of these dis- locations can be understood from what has been already said as to the action of the ligaments in restricting movements. ' Acromio-clavicular joint. This articulation is shallow, and the outlines of the two bones that enter into its formation are such that no obstacle is offered to the displacement of the clavicle from the acromion. The joint, indeed, depends for its strength almost entirely upon its ligaments. The plane of the joint would be represented by a line drawn from above downwards and inwards be- tween the two bones. This inclination of the joint- surfaces serves to explain the fact that the usual luxation of this part takes the form of a dis- placement of the clavicle upwards on to the acromion. As the movements permitted in this joint may be impaired by accident or disease, it is well to note the part the articulation takes in the move- ments of the extremity. The scapula (and with it, of course, the arm), as it glides forwards and backwards upon the thorax, moves in the arc of a circle whose centre is at the sterno-clavicular joint, and whose radius is the clavicle. As the bone moves forwards it is important, for reasons to be immediately given, that the glenoid cavity should also be directed obliquely forwards. This latter desirable condition t is brought about by means of the acromio-clavicular joint. Without this joint the whole scapula as it passed forwards with the outer end of the clavicle would precisely follow the line of the circle above mentioned, and the glenoid cavity would look in an increasingly inward direction. It is essential that the surface of the glenoid cavity should be maintained as far as possible at right angles to the long axis of the humerus. When these relations are satisfied, the xi] ACROMIO-CLAVIGULAR JOINT 249 humerus has the support behind of a stout sur- face of bone, and it is partly to obtain the value of this support that the boxer strikes out from the side, i.e. with his humerus well backed up by the scapula. If there were no acromio-clavicular joint the glenoid fossa would offer little support to the humerus when the limb was stretched for- wards, and a blow given with the limb in that position, or a fall upon the hand under like con- ditions, would tend to throw the humerus against the capsule of the shoulder-joint, and so produce dislocation. Normally, therefore, as the scapula and arm advance, the angle between the acromion and the adjacent portion of the clavicle becomes more and more acute, and the glenoid fossa is maintained with a sufficiently forward direction to give substantial support^to the humerus.* It will thus be seen that rigidity of this little joint may be a cause of insecurity in the articulation of the shoulder, and of weakness in certain move- ments of the limb. There is also movement in this joint as the arm is lifted towards the head, the angle between the clavicle and axillary border becoming more acute as the shoulder is elevated. Dislocations of the acromio-clavicular joint. The clavicle may be displaced upwards on to the acromion, or downwards beneath it. Polaillon has collected 38 cases of the former luxation, and 6 only of the latter. This disproportion is, in the main, explained by the. direction of the articulating surfaces of the joint. Scapula. At the posterior or dorsal aspect of the bone the muscles immediately above and below the spine are bound down by the deep fascia. Thus, the supraspinatus muscle is en- closed in a fascia that, being attached to the bone all round the origin of the muscle, forms a cavity open only towards the insertion of the muscle. The infraspinatus and teres minor muscles are * For an excellent account of the mechanism of these joints, see Morris's " Anatomy of the Joints," p. 202 et seq. 250 THE UPPER EXTREMITY [CHAP. also enclosed in a distinct, but much denser, fascia that is attached to the^bone beyond these muscles, and blends in front with the deltoid sheath so as to form a second enclosed space. The arrange- ment of these fasciae serves to explain the trifling amount of ecchymosis that usually follows upon fractures of the scapular blade. The extravasa- tion of blood about the fracture is bound down by the fasciae over these muscles, and is unable, therefore, to reach the surface. Movements of the scapula. In lifting the arm from the side to a vertical position over the head a double movement takes place (1) between the scapula and the trunk; (2) between the humerus and the scapula, at the shoulder-joint. The extent of the movement in the first joint is only about 45, whereas in the second it is about 100. The one joint is accessory to the other. Hence, in ankylosis of the shoulder- joint, we can still attain a certain degree of abduction and adduction of the arm, the whole upper extremity moving with the rotating scapula. To obtain this result the arm must be abducted from the side before ankylosis sets in. As the extremity is raised the scapula undergoes a free rotatory movement, its vertebral border passing from an approximately vertical to an approxi- mately horizontal position. At the commencement of the movement, until the arm has ascended 35 from the side, the angle of the scapula is practically stationary; during this stage the scapula is fixed and maintained in position by the trapezius, rhomboids, and serratus magnus. If the trapezius is paralysed, as may result from accidental section of the accessory (spinal acces- sory) nerve in removing glands from the neck, the inferior angle and vertebral border project backwards, under the weight of the raised arm; the acromial region of the shoulder drops down- wards and forwards. When the arm passes beyond 35, the serratus magnus comes into action, and the inferior angle of the scapula xi] FRACTURES OF THE SCAPULA 251 moves rapidly forwards. If the nerve to this muscle be paralysed (the long thoracic from 5, 6, 7 c.) or if its antagonists the rhomboids- which are also then in action, be paralysed (nerve from 5 c.), then the angle and posterior border of the scapula become prominent or " winged "- evidence of the paralysis of these muscles. Thus "winging" of the scapula at the commencement of the movement indicates paralysis of the trape- zius; if it occurs after the movement is well begun, then the serratus magnus is affected. Fractures of the scapula, and especially of the body of the bone, are not common, owing to the mobility of the part and the thick muscles that cover in and protect its thinner portions. It rests also upon a soft muscular pad, and derives, no doubt, additional security from the elasticity of the ribs. The most common lesion is a fracture of the acromion process. This is often but a separation of the epiphysis. There are two, sometimes three, epiphyseal centres for the acromion. Ossification appears in them about puberty, and the entire epiphysis joins with the rest of the bone from the twenty-second to the twenty-fifth year. Several cases of supposed fracture of the acromion united by fibrous tissue are probably but instances of an imperfectly-united epiphysis, and may have been independent of injury. In 5 bodies out of 40 Symington found the acromial epiphysis united to the spine by a fibrous union, and from the statistics of other^ observers it appears that this is the case in quite 10 per cent, of adults. In fractures of the process much displacement is quite uncommon, owing to the dense fibrous cover- ing the bone derives from the two muscles attached to it. The coracoid process may present a genuine fracture, or may be separated as an epiphysis. As an epiphysis, it joins the main bone about the age of 17. The supraglenoid tubercle, from which the long head of the biceps takes its origin, is part of the coracoid epiphysis. In spite of 252 THE UPPER EXTREMITY [CHAP. the powerful muscles that are attached to the coracoid, the displacement Is usually slight, inas- much as the coraco-clavicular ligaments are seldom torn. These ligaments, it may be noted, are attached to the base of the process. In some few cases the process has been torn off by muscular violence. Among the more usual fractures of the body of the^ scapula is a transverse or oblique fracture of its blade below the spine. Owing to the infra- spinatus, subscapularis, and other muscles being attached to both fragments, none but a trifling displacement is usual. A fracture may occur through the surgical neck. The surgical neck is represented by a narrowed part of the bone behind the glenoid fossa, and in the line of the suprascapular notch (incisura scapularis). The smaller fragment will, therefore, include the coracoid process; the larger, the acromion. Tumours of the scapula. Tumours of various kinds grow from the scapula, and mainly from the spongy parts of the bone viz. the spine, the neck, and the inferior angle. It may be sufficient to excise the scapula alone, but it must be remembered that the main fulcrum on which the upper extremity rotates is then removed. It is therefore more usual in such cases to perform an inter scapulo-thoracic amputation, which is usually done for malignant tumours involving structures in the neighbourhood of the shoulder- joint. In this operation the upper extremity, including the scapula and the clavicle beyond the origin of the sterno-mastoid, is removed. An elliptical incision is made in front of and behind the shoulder, the upper end of the ellipse lying on the clavicle, the lower at the angle of the scapula. The operation is begun at the clavicle so as to secure the axillary vessels. The artery is tied before the vein so that the limb may continue to empty its blood into the circulation. The main vessels to be noted in connexion with this operation are the suprascapular (transverse xi] THE AXILLA 253 scapular) at the superior border of the bone, the posterior scapular (branch of the transverse cervical) about the vertebral border, the sub- scapular running along the lower border of the subscapularis muscle, the dorsalis scapulae crossing the axillary edge of the bone, and the acromial branches of the acromio-thoracic artery. The axilla. The axilla may be regarded sur- CORACOIO ACROMION GT. TUB. BICIP. GROOVE CIRCIHVI. N. DELTOID Fig. 58. Relationship of the axillary artery and brachial plexus to the shoulder-joint and axilla. gically as a passage between the neck and the upper limb (Fig. 58). Axillary tumours and abscesses may spread up into the neck, and in like manner cer- vical growths and purulent collections may extend to the armpit. The skin forming the base of the axilla is provided with" many short hairs and with numerous sebaceous and sudoriparous glands. In this integument small superficial abscesses are often met with, that arise usually from suppura- tion of these glandular structures, and that are 254 THE UPPER EXTREMITY [CHAP. brought about by the friction of the skin against the clothing. Owing to the tendency of the axil- lary integument to become chafed and inflamed under friction, the axilla is not a good locality to select for the use of the mercurial inunction as applied in syphilis. Beneath the skin and super- ficial fascias is the axillary fascia, and beyond this membrane is the axillary space. The connective tissue with which the axillary space is mainly occupied is very loose, and, while this laxity favours greatly the free movement of the arm, it at the same time permits of the formation of large purulent collections and immense extravasations of blood. It is important to remember the disposition of the fasciae about this region. There are three layers principally concerned. (1) The deep pec- toral fascia which covers in and encloses the pector- alis major. (2) The clavi-pectoral fascia which, adherent above to the clavicle, fills in the space between that bone and the pectoralis minor, then splits to invest this muscle, and joins the deep pectoral layer at the anterior fold of the axilla to form with it the axillary fascia. The upper part of this fascia is generally known as the costo- coracoid membrane. The whole membrane is some- times known also as the " suspensory ligament of the axilla," since it draws up the axillary fascia towards the clavicle, and is mainly instrumental in producing the " hollow " of the armpit. (8^ The axillary fascia which is formed by the union of the two preceding fasciae, and stretches across the base of the axilla from its anterior to its posterior fold. It is thinnest under the axillary hairs. Abscess about the axillary region may be formed beneath the pectoralis major, or between^the two pectoral muscles, or beneath the pectoralis minor and clavi-pectoral fascia, and therefore in the axillary space. The loose tissue of the axillary space allows the formation of a large abscess cavity. The abscess as it fills the axilla pushes forwards the pectoralis major, more or less obli- xi] AXILLARY ABSCESS 255 terates the hollow of the armpit, thrusts back the scapula, and widens the angle between the serratus magnus (anterior) and the subscapularis muscles. There is a great tendency, therefore, for unrelieved abscesses to extend upwards into the neck, that being the direction in which the least amount of resistance is encountered. From the neck the purulent collection may extend into the mediastinum. In one case an axillary abscess, set up by shoulder-joint disease, perforated the first intercostal space and set up fatal pleurisy. In opening an axillary abscess, and, indeed, in most incisions into this space, the knife should be entered at the centre of the floor of the axilla, i.e. midway between the anterior and posterior margins, and near to the inner or thoracic side of the space. The vessels most likely to be damaged by an indiscreet incision are the subscapular, running along the lower border of the subscapu- laris muscle; the lateral (long) thoracic, follow- ing the lower border of the small pectoral; and the main vessels lying close to the humerus. The knife, if properly entered, should be mid- way between the two first-named vessels, and quite away from the main trunks. There is an artery that sometimes comes off as the lowest branch of the axillary trunk, and crosses the middle of the axilla, to be distributed to the thorax below the long thoracic. This vessel would probably be wounded in the incision above named. The artery is, however, very inconstant, is small, and is not far below the surface. It is usually met with in female subjects. Lymphatic glands of the axilla. The axillary glands are numerous, and of much surgical im- portance (see Fig. 53, p. 222). They may be arranged in four sets. (1) The greater number are placed to the inner side of the axillary vein beneath the axillary tuft of hair. This central set of glands receives the lymph from the upper extremity and breast. Pain in the axilla which follows whitlow or any septic infection of the arm 250 THE UPPER EXTREMITY [CHAP. is due to inflammation of this group, which is pierced by the intercosto-humeral nerve. (2) The deep axillary set lies along the axillary vessels. It receives the lymph from the central set and becomes continuous with the lower deep cervical glands in the subclavian triangle. (3) Other glands lie upon the serratus magnus muscle on the thoracic side of the axilla, and just behind the lower border of the pectoral muscles. They receive the lymphatics from the front of the chest, the princi- pal lymjDh-vessels of the breast, and the superficial lymphatics of the abdomen as low down as the umbilicus. Their efferent vessels for the most part pass on to join the central set of glands. These glands will be the first to be enlarged in certain breast affections, and after blistering and other superficial inflammations, etc., of the chest and upper abdomen. The axillary process of the female breast is in contact with this set. (4) The remaining glands are situated at the back of the axilla, along the subscapular vessels. They are joined by the lymphatics from the scapular and lumbar regions of the back. It may here be convenient to note that one or two glands are commonly found in the groove between the deltoid and pectoralis major muscles. They receive some vessels from the outer side of the arm and a part of the shoulder and breast. The superficial lymphatics over the upper part of the deltoid go to the cervical glands (Tillaux), over the lower half to the axilla. The lymphatics from the supraspinous fossa follow the supra- scapular (transverse scapular) artery, and join the lowest cervical glands. The superficial lymphatics of the back which converge to the axilla are derived from the neck over the trapezius muscle, and from the whole dorsal and lumbar regions as far down as the iliac crest. The complete removal of axillary glands is an operation frequently undertaken, especially in cases of mammary cancer. Free access to them is obtained by reflecting the pectoral muscles xi] VESSELS OF THE AXILLA 257 inwards. It will be understood from their posi- tion that these bodies, when diseased, are very apt to become adherent to the axillary vessels, and especially to the vein. The latter vessel has frequently been wounded or excised during the removal of gland tumours, and one case at least is recorded in which the artery was acci- dentally cut (Holmes). Axillary vessels. The axillary vein is formed by the union of the basilic with the two venae comites of the brachial artery. This union com- monly takes place at the lower border of the pectoralis minor muscle, and the vein is therefore shorter than the artery. Sometimes the vein does not exist as a single trunk until just below the clavicle. This condition, when present, is very unfavourable to operations upon the artery, as many transverse branches cross that vessel to unite the veins that lie on either side of it. The axil- lary vein, being comparatively near the heart, is readily influenced as regards its contained blood by the inspiratory movement. Thus it happens that, in many instances of wound of the vessel or of its larger tributaries, air has been drawn into the venous canal and death has ensued. The en- trance of air into the main vein is perhaps aided by the circumstance that the costo-coracoid mem- brane (upper part of the clavi-pectoral fascia) is adherent to the vessel, and thus tends to maintain it in a patent condition when wounded. This connexion with the fascia is supposed by some to account in part for the furious bleeding that occurs from this vein when it is divided. The vein is more often wounded than is the artery, it being larger, more superficial, and so placed as more or less to ^ overlap the arterial trunk. On the other hand, in injury to the vessel by traction, as, for example, in reducing disloca- tions, the artery suffers more frequently than the vein. In all positions of the upper limb the artery keeps to the outer angle of the axillary space. The relation of the vein, however, to the j 258 THE UPPER EXTREMITY [CHAP. first part of the axillary artery, the part above the pectoralis minor, is modified by the position of the limb. Thus, when the arm hangs by the side the vein is to the inner medial side of the artery, and a little in front of it, but when the limb is at a right angle with the trunk the vein is drawn so far in front of the artery as almost entirely to conceal that vessel. Aneurysm is very frequent in the axillary artery, a fact to be explained by the nearness of the vessel to the heart^by the abrupt curve it pre- sents, by its susceptibility to frequent and exten- sive movements, and by its liability to share in the many lesions of the upper limb. In violent and extreme movements of the limb the artery may be more or less torn, especially if its walls are already diseased. In ligaturing the first part of the axillary artery it is well to note that the pectoralis major has sometimes a cellular interval between two planes of muscle fibre, and this may be mistaken for the space beneath it (Heath). If the pector- alis minor has an origin from the second rib, it may more or less entirely cover the artery and re- quire division. The cord of the brachial plexus nearest to the artery may^ be mistaken for that vessel, or easily included in a ligature intended for it. A ready guide to the axillary vessels in this operation is to follow the cephalic vein. The anterior internal thoracic nerve appears between the vein and artery as it passes to the pectoralis minor; it also may be useful occasionally as a guide. In applying a ligature to the third part of the artery, it should be borne in mind that a mus- cular slip sometimes crosses the vessels obliquely, passing from the latissimus dorsi to join the pec- toralis major, coraco : brachialis, or biceps mus- cles. This slip may give rise to confusion during the operation, and may 'be mistaken for the coraco-brachialis. Brachial plexus. When the shoulder is depressed xi] BRACHIAL PLEXUS 259 the upper and middle trunks of the brachial plexus, formed by the fifth, sixth, and seventh cervical nerves, can be distinctly felt in the neck, passing from beneath the posterior border of the sterno-mastoid to enter the axilla just ex- ternally to the mid-point of the clavicle (Fig. 58). As the trunks of the plexus pass towards the upper surface of the first rib, where they lie above and dorsally to the subclavian artery, the nerve-trunks are surrounded by a lax connective tissue, permitting free movements of the plexus as the shoulder is elevated and depressed. It is at this part of the supraclavicular region where the nerve-cords can be felt above and behind the pulsations of the artery, particularly when the patient is sitting up with the shoulder depressed, that injections are made into the plexus to produce ancesthesia in the arm. The upper trunk, formed by the fifth and sixth nerves, is by far the most exposed to injury, for the reason that it rises higher in the neck than the middle and lower trunks; consequently, if the neck is bent forcibly to the left, as when a burden is borne on the < right shoulder, the upper trunk on the right side is subjected to a greater strain than the middle or lower cords (Fig. 59). In cases of shoulder- presentation at birth, or if the neck and shoulder be forced apart by accident, the upper cord is liable to be strained or ruptured, resulting in what is usually described as Erb's palsy. It will be recalled that the suprascapular, circumflex (axillary), and musculo-cutaneous nerves are de- rived from this trunk; so are the nerves to the rhomboids and serratus magnus. The rupture, however, is usually distal to the origin of these nerves, and hence their muscles escape. The muscles affected in Erb's palsy are thesupraspinatus, infra- spinatus, teres minor, deltoid, coraco-brachialis, biceps, brachialis, and brachio-radialis ; occasion; ally also the supinator (brevis), extensor carpi radialis longior, and pronator (radii) teres. No 260 THE UPPER EXTREMITY [CHAP. sensory paralysis is observed in such cases. Curi- ously enough, section of the fifth cervical gives as wide an area of muscular paralysis as section of the combined fifth and sixth (Wilfred Harris). In complete rupture of the brachial plexus, sensa- tion is completely lost beyond the elbow, but in the arm and shoulder deep sensibility is retained (Sherren). The arm, in such lesions, retains intact 3 C. Ml/SCs-SflRAL POST. CIRCUMFLEX Fig. 59. Upper and middle trunks of the brachial plexus viewed from behind to show how depression of the shoulder or lateral abduction of the head may produce stretching and injury of the nerve-cords. {After Poiricr.) the nerves received from the descending cervical and intercosto-humeral. Axillary nerves. Any of the axillary nerves may be injured by a wound, the median being the most frequently damaged, and the musculo- spiral ^the least frequently. The comparative immunity^ of the latter is explained by its deep position, its situation at the inner and posterior XI] DELTOID REGION 261 aspect of the limb, and its large size. The nerves are very seldom torn by a traction on the limb short of more or less complete avulsion. Indeed, if forcibly stretched, they are disposed rather to become torn away from their attachments to the spinal cord than to give way in the axilla. Thus, Flaubert records a case where the last four cervi- cal nerves were torn away from the cord during a violent attempt to reduce a dislocated shoulder. UPRASPINATUS SCAPULA 1- CAPSULE __/POST.ClR.CU/MFLE:X AR.T Fig. 60. Section of shoulder-joint to show the relations of the capsule, epiphyseal line, and bursa. (After Poirier.} The deltoid region. This region, comprising as it does the " point " of the shoulder, is limited in all parts by the deltoid muscle. The deltoid covers the upper end of the humerus and the shoulder-joint (Fig. 60). Between the joint and the surface, therefore, are only the skin and super- ficial fascia, the deltoid in its sheath, and some loose connective tissue (the' subdeltoid tissue) in which is found the great subdeltoid (subacromial) 262 THE UPPER EXTREMITY [CHAP. bursa. This subdeltoid tissue sometimes assumes the form of a distinct thick membrane, and may have an important influence upon the localization of purulent collections proceeding from the joint. The fatty tissue over the deltoid is a favourite seat for lipomata, and it is in this situation that the tendency of these growths to change their position is sometimes seen. Thus, Erichsen records a case where the tumour slid downwards from the shoulder to the breast. Emerging from the interval between the two teres muscles, and winding horizontally round the shaft of the humerus, quite close to the bone, and about the line of the surgical neck, are the circum- flex nerve and posterior circumflex artery (Fig. 58, p. 253, and Fig. 85, p. 392). This nerve affords an example of an arrangement pointed out by Hilton, viz. that a principal nerve to a joint not only supplies the articular surfaces, but also some of the main muscles that move that joint, and the skin over those muscles. This nerve supplies the shoulder-joint, the deltoid and teres minor muscles, and the skin over the lower two-thirds of the shoulder and upper part of the triceps. It is frequently damaged in injuries to the shoulder, and may be severely bruised by a simple contusion of the part, resulting in paralysis of the deltoid. It would appear, however, that damage to the circumflex is much less frequent after contusions of the shoulder than was formerly maintained. It will also be readily understood that the nerve is often torn in fractures of the surgical neck of the humerus, in dislocations of that bone (especially the luxa- tion backwards), and in violent attempts at reducing such dislocations (Figs. 58 and 59). The shoulder-joint. From one surgical point of view, joints may be divided into (1) those that depend -for their strength mainly upon ligaments ; (2) those that are mechanically strong, and that derive their stability to a great extent from the arrangement of their component bones; and (3) XT] THE SHOULDER- JOINT 263 those that rely for their support principally upon muscles. As an example of the first kind may be cited the sterno-clavicular joint, of the second form the elbow- joint, and of the third the shoulder- joint. m The articulation the least prone to dislocation is the one that derives its strength from tough unyielding ligaments, while the one most often luxated belongs to the third variety, its strength being greatly dependent upon muscles that may be taken by surprise, and that may them- selves, from disordered action, prove sources of weakness. These are, of course, not the only fea- tures in the etiology of dislocation. A great deal depends upon the amount of movement permitted in a given joint, and the degree of leverage that can be brought to bear upon its parts. The arch formed by the coracoid and acromion processes and the ligament between them forms an essential support to the head of the humerus, and is an important constituent of the articulation. With this arch the humeral head is in immediate relation, though not in actual contact (Fig. 60). In paralysis of the deltoid the head may be separated by some distance from the coracoid process, and Nannoni records the case of a child with old-standing paralysis of the deltoid between whose humeral head and acromial vault four fin- gers could be lodged. It is well to note that at least two-thirds of the head of the bone are not in contact with the glenoid cavity when the arm hangs by the side, and Anger points out that in this position three-fourths of the circumference of the humeral head are in front of a vertical line drawn from the anterior border of the acromion process. In this posture, also, the head is wholly to the outer side of the coracoid process. The margin of the glenoid cavity is more prominent on the inner than on the outer side, while the strongest part of the margin and the broadest part of the fossa are below. This is significant, since it points to an attempt to strengthen a part of the joint that practice shows to be the weakest 264 THE UPPER EXTREMITY [CHAP. in the articulation, viz. the lower and inner por- tion of the capsule. It is at this place that the head of the bone leaves the joint in dislocation of the shoulder. The capsule of the shoulder- joint is very lax, and would lodge a bone-head twice as large as that of the humerus. According to Sir Henry Morris, no one part of the capsule is constantly thicker than the rest, as is the case in the hip-joint. Of the bursae about the joint, the subacromial bursa is the one most frequently the seat of disease. This sac, when distended with fluid, may be mis- taken for the results of chronic inflammation of the joint (Fig. 60). Experiment shows that the walls of this bursa may be actually torn in twists of the arm, espe- cially when either flexed or extended. When the sac is distended, most pain is elicited in the position of abduction, for in this posture the bursal walls are normally folded up, so as to form a sort of collar in advance of the greater tuberosity. In elderly rheumatic people the sac sometimes communicates with the joint. The sub- scapular bursa may be regarded as an extension of the synovial membrane of the joint between the terminal part of the muscle and the scapula. Pain elicited when the arm is rotated at the shoulder-joint may be due to disease in the joint, or in the subacromial or the subscapular bursa, for a movement then occurs in all three. The biceps tendon strengthens the upper part of the joint, keeps the humerus against the glen- oid cavity in the various positions of the limb, and prevents the head of the bone from being pulled too closely upwards under the acromion. The tendon may be ruptured, and in such a case, in addition to the general weakening of the limb, and the peculiar projection formed by the con- traction of the muscle, the head of the humerus is usually drawn upwards and forwards until ar- rested by the coraco-acromial arch. Thus, a kind of slight false dislocation may be produced. In xi] DISEASE OF SHOULDER-JOINT 265 certain violent wrenches of the limb the tendon may rupture the transverse ligament which binds it down, slip from its groove, and be displaced to one or other side, usually to the inner side. The intracapsular part of the tendon may ^dis- appear in cases of chronic rheumatic arthritis, owing to the friction against the abraded arti- cular surface of the .humerus. In such cases it acquires an attachment to the bicipital groove. Disease of the shoulder=joint. This articulation is liable to all forms of joint-disease. The capsule, as just stated, is very lax, the articular surfaces being kept in apposition by the tonus of the sur- rounding muscles ; when chloroform is administered the surfaces may be freely separated and examined. In joint-disease, however, the effusion may effect a considerable separation of the two bones. Braune, having pierced the glerioid cavity through the supraspinpus fossa, injected tallow at considerable pressure into the joint. When fully distended the humerus was found to be separated from the scapula by more than \ an inch, and this may serve to explain the lengthening of the limb often noted in joint-disease of this part with much effusion. When the greatest degree of distension of the capsule was reached the humerus became slightly extended and rotated inwards. It is significant that in shoulder-joint disease it is com- mon for the arm to be found close to the side, the elbow carried a little back (extension), and the limb rotated inwards. This position may also be due to the rigid contraction of the muscles about the joint. When such contractions exist it may be inferred that the powerful latissimus dorsi has a little advantage over its opponents, and may be answerable for the rotation in and slight projection ^backwards of the arm. The inner part of the epiphyseal line is just within the cap- sule; the outer, anterior and posterior parts are entirely subperiosteal. It happens, therefore, that the jpus in suppurative epiphysitis will find its way into the joint. 266 THE UPPER EXTREMITY [CHAP There are two diverticula from the synovial membrane : (1) one that runs some way down the bicipital groove (intertubercular sulcus) with the tendon; (2) a cul-de-sac beneath the subscapu- laris formed by a communication between the synovial cavity and the bursa under that muscle. When the joint is filled with effusion the cap- sule is evenly distended and the shoulder evenly rounded. Special projections usually occur at the seats of the diverticula. Thus a swelling often appears early in the course of a synovitis in the groove between the pectoralis major and the deltoid muscles, and this swelling may ap- pear bilobed, being cut in two by the unyielding biceps tendon. Fluctuation can best be felt by examining the uncovered part of the capsule in the axilla beyond the subscapular muscle. When the joint suppurates, pus usually escapes at one of the culs-de-sac just mentioned, most often through the one that follows the biceps tendon. Pus may thus extend for some way along the bicipital groove. In one recorded case, pus that had escaped from the shoulder-joint followed the course of the musculo-spiral (radial) nerve, and opened on the outer side of the elbow. Dislocations. Dislocations at this joint are more common than at any other joint in the body. This is explained by the shallowness of the glenoid fossa, the large size and globular shape of the head of the humerus, the extensive movements of the arm, the long leverage it affords, and the depend- ence of the articulation for its strength mainly upon muscles. The upper limb and shoulder are also peculiarly exposed to injury. The principal forms of luxation of the humerus at the shoulder are : 1 Subcoracoid, forwards and a little downwards; the usual form. 2. Sub- fjlenoid, downwards and a little forwards; rare. 3. Subspinous, backwards; rare. In all complete dislocations the head of the bone leaves the joint-cavity through a rent in the capsule. In so-called "false luxations" the xi] DISLOCATIONS OF SHOULDER-JOINT 267 capsule is not torn. For example, in the cadaver, if the deltoid be divided the humeral head can be displaced under the coracoid process without rupture of the capsule; and the same thing may occur during life, in cases where the muscle has long been paralysed. In all cases of dislocation at this joint the primary displacement is always downwards into the axilla. It is well known that dislocations at the shoulder are usually due to violence applied to the limb while the arm is abducted, or to severe direct violence forcing the bone downwards. Now, when the limb is abducted the head of the humerus projects below the glenoid fossa, and rests and presses upon the inferior and least protected part of the capsule. The fibres of this portion of the capsule being tightly stretched in this position, it requires the exertion of no extraordinary force to tear the ligament and drive the bone into the axilla. Thus it happens that in luxations at this joint the rent in the capsule is at its inferior and inner aspect, the humeral head lying beneath the sub- scapularis, which is always strained and some- times torn. The head of the bone, being thus driven downwards into the axilla, may, for cer- tain reasons, remain there (subglenoid form), or more usually it will be drawn forwards and in- wards by the powerful pectoralis major, aided by other muscles whose action is now less resisted and by the weight of the unsupported limb (sub- coracoid form); and lastly, the direction of the violence being applied markedly from in front, the head of the bone may be thrust backwards under the acromion or spinous processes (sub- spinous form). The overwhelming frequency of the subcoracoid variety is explained by the greater advantage at which those muscles act that draw the bone forwards, in comparison with those that would draw it backwards, and by the very trifling opposition offered to the passage of the head forwards when compared with the substantial 268 THE UPPER EXTREMITY [CHAP. obstacles in the way of its passage backwards under the scapular spine. Features common to all dislocations at the shoulder. As the roundness of the deltoid depends to a great extent upon the presence beneath it of the humeral head, and as in all these luxations (save perhaps in the slighter grades of the subspinous form) the head is removed practi- cally from its connexion with the deltoid, that muscle is always more or less flattened. This flattening is augmented by the stretching of the muscle which in some degree is constantly present. Stretching of the deltoid involves abduction of the arm, and this symptom is fairly constant in all the luxations. The biceps being also more or less unduly tense, the elbow is found flexed and the forearm supinated. In every form there is some increase in the vertical circumference of the axilla, since the head, having left the glenoid fossa, must occupy some part comprised within that circumference. Again, Dr. Dugas has pointed out that " if the fingers of the in- jured limb can be placed by the patient, or by the surgeon, upon the sound shoulder while the elbow touches the thorax (a condition that obtains in the normal condition of the joint), there can be no dislocation ; and if this cannot be done there must be one, for no injury other than a disloca- tion can induce this physical impossibility." This depends upon the fact that in consequence of the rotundity of the thorax it is impossible for both ends of the humerus to touch it at the same time, and in luxation at the shoulder the upper end of the bone is practically touching the trunk. Lastly, from the position of the great vessels and nerves (Fig. 58) it will be seen that in the subcoracoid and subglenoid luxations the head of the bone may press injuriously upon those structures. Thus may result O3dema of the limb and severe pain or loss of muscular power. ^ The artery is usually saved by its greater elasticity ; but Berard reports a case of displacement forwards where XI] SUBCORACOID DISLOCATION 269 the axillary artery was so compressed by the humeral head as ;to induce gangrene of the limb. The close connexion of the circumflex nerve with the humerus renders it very liable to injury, especially in the subglenoid and subspinous forms of dislocation. Special anatomy of each form of shoulder dis= location. 1. Subcoracoid. The articular head of the humerus lies on the anterior surface of the neck of the scapula, and the anatomi- cal neck rests on the anterior lip of the g 1 e n o i d fossa. The head is thus placed imme- diately below the coracoid process, and is in front of, internal to, and a little below its normal site. The great tuberosity faces the emj)ty g 1 e n o i d cavity (Fig. 61). Thesub- scapularis muscle is stretched over Fig. 61. Subcoracoid dislocation the head of the of the humerus. humerus, and is usually partly torn. The supraspinatus, infra- spinatus, and teres minor are stretched or torn, or the great tuberosity may even be wrenched off. The coraco-brachialis and short head of the biceps are tense, and are immediately in front of the head of the humerus instead of to its inner side. The long tendon of the biceps is deflected downwards and outwards. It is some- times, although rarely, torn from its groove. The deltoid is put upon the stretch. The prominence 270 THE UPPER EXTREMITY [CHAP. formed by the humeral head in the front of the axilla depends to some degree upon the amount of rotation. If the bone be rotated out, the projection is most distinct; but if rotated in, its head sinks into the axilla and is brought more in contact with the scapula than with the skin. The head of the bone being always carried a little downwards, some lengthening must in all cases really exist; but with the ordinary method of measuring the limb this lengthening may be replaced by a normal measurement, or even by apparent shortening, if the head of the bone be carried a good deal forwards and inwards, and the limb be abducted. When the head has left the glenoid cavity, abduction tends to bring the external (lateral) condyle nearer to the acromion, and these are the two points between which the measurement is usually taken. Thus the apparent length of the arm depends mainly upon the degree of abduction of the humerus, or the obliquity of the axis of the bone. 2. Subglenoid. The head is below, and a little in front of and internal to, its normal position. It cannot go directly downwards, owing to the situation of the long head of the triceps, but escapes in the interval between that muscle and the subscapularis. The articular surface of the head rests on the anterior aspect of the triangular area just below the glenoid fossa that gives origin to the triceps.^ The upper border of the great tuberpsity is in close relation with the lower margin of the joint. The subscapularis muscle, which binds down the humeral head, is much stretched or torn. The supraspinatus and the infraspinatus are stretched or torn, and the two teres muscles have not been much affected unless there be considerable abduction of the arm. The coraco-brachialis and biceps are stretched, and owing to the amount of abduction usually present, the biceps tendon is but little deflected from a straight line. 3. Subspinous. The head usually rests on the XI] SUBSPINOUS DISLOCATION 271 posterior surface of the neck of the scapula, the groove of the anatomical neck of the humerus corresponding to the posterior lip of the glenoid fossa. The head is thus placed beneath the acromion ; but it may be displaced still farther back, and may rest on the dorsum scapulae, and beneath the scapular spine (Fig. 62). The sub- scapular is tendon is drawn right across the glenoid fossa, and is often torn from its attach- ment. The head pushes back the hinder part CT of the deltoid, the in- \ fraspinatous and teres minor muscles. These latter cover the bone, and are stretched over it. The great pectoral is rendered unduly tense, and this serves in part to explain the rotation inwards of the humerus, and the abduction forwards, which are usually observed, those movements being more or less unopposed. The circumflex nerve is often torn. In reducing dislo- cations, and especially such as are of long standing, serious damage may be inflicted on the axillary structures. The axillary artery suffers most frequently, the vein rarely, and the nerves still less often. The artery, being placed externally, is apt to contract ad- hesions to the soft parts covering the head of the displaced bone, and therefore to be torn when those parts are disturbed (Fig. 58). Fractures of the upper end of the humerus. 1. Anatomical neck. The upper part of the capsule is exactly attached to the anatomical Fig. 62. Subspinous disloca- tion of the humerus. 272 THE UPPER EXTREMITY [CHAP. neck, and in this situation the fracture may run beyond the ligament and be partly extracapsular (Fig. 60, p. 261). The lower part of the capsule is inserted some little way below the anatomi- cal neck, and in this position, therefore, the lesion must be intracapsular. From the lino of attachment of the lower part of the capsule to the humerus, fibres are reflected upwards to the margin of the articular cartilage on< the head of the bone. These fibres, if unruptured, may serve to connect the fragments. It is easy for the small and comparatively dense upper fragment to be driven into the wide extent of cancellous bone exposed on the upper surface of the lower fragment. When impaction occurs, there may be some flattening of the deltoid, since the head is rendered of less dimensions by that impaction, and consequently causes a less projection of the deltoid. The difficulty of obtaining crepitus in non-impacted fractures will be obvious when the small size of the upper fragment is considered, together with its great mobility, and the obstacles in the way of so fixing it that one broken end may be rubbed against the other. The diagnosis of such obscure cases is now cleared up by the aid of the X-rays. 2. Separation of the upper epiphysis. The lower border of this epiphysis is represented by a line crossing the bone at the base of the great tuberosity and placed between the anatomical and surgical necks (see Fig. 60, p. 261). It would be fairly indicated by a transverse saw-cut through the widest part of the bone. The three component nuclei of this epiphysis (head, greater and lesser tuberosities) fuse together about the fifth year, and the entire mass joins the shaft about the twentieth year. The upper fragment may be carried and rotated a little outwards by the muscles attached to the great tuberosity, while the lower fragment is drawn inwards and for- wards by the muscles inserted into the bicipital groove. Thus, a part of the smooth upper end of xi] FRACTURES OF HUMERUS 273 the lower fragment commonly forms a distinct projection below the coracoid process. In such case the axis of the limb would be altered, and the elbow carried a little from the side. Often, however, the displacement is solely in the antero- posterior direction, the lower fragment project- ing forwards. So wide are the two bone surfaces at the seat of injury that it is scarcely possible for them to overlap one another. 3. Surgical neck. The surgical neck is situated between the bases of the tuber osities and the in- sertions of the latissimus dorsi and teres major muscles. A common displacement of parts is the following : The upper fragment is carried out and rotated put by the supra- and infraspinatus and teres minor. The upper end of the lower fragment is drawn upwards by the deltoid, biceps, coraco-brachialis, and triceps, inwards by the muscles attached to the bicipital groove, and for- wards by the great pectoral. Thus it forms a projection in the axilla, and the axis of the limb is altered so that the elbow projects from the side. This displacement, however, is by no means con- stant. Pean, Anger, and others maintain that the usual deformity is a projection of the upper end of the lower fragment forwards, and that this deviation is due to the nature and direction of the violence, and not to muscular action. In some cases there is no displacement, the broken ends being retained in situ, probably by the biceps tendon and the long head of the triceps. In at least one instance (Jarjavay) the lower fragment was so drawn upwards and outwards, apparently by the deltoid, as nearly to pierce the skin of the shoulder. Hamilton comes to the general con- clusion " that complete or sensible displacement is less common at this fracture than in most other fractures," and in this conclusion many surgeons agree. Amputation at the shoulder-joint. The deltoid muscle forms an ideal amputation flap. It has its blood and nerve supply secured for it by the 274 THE UPPER EXTREMITY posterior circumflex vessels and circumflex nerve, which require to be avoided as the flap is raised from the posterior aspect of the upper extremity of the humerus prior to division of the capsule. The coracoid process lies under the anterior border of the muscle, and immediately external to the line of the axillary vessels. Thence the preliminary incision, which commences just externally to the coracoid, and is carried down the arm along the anterior border of the muscle, gives access to the axillary vessels so that they may be secured below the origin of the superior profunda (deep artery of arm). The incision is carried backwards above the insertion of the deltoid to the humerus. The insertion of the pectoralis major is cut in the incision along the anterior border of the deltoid ; so are the latissimus dorsi and teres major. The insertions of the teres minor, infraspinatus, supraspinatus, and subscapularis are adherent to the capsule and are cut through with it, so as to free the head of the bone. The lower part of the capsule and the long head of the triceps are severed after the head of the humerus has been raised from its socket through the upper wound. In excision of the head of the humerus for disease of the shoulder-joint, an incision is made along the line of the tendon 9f the supraglenoid head of the biceps, the incision being deepened until the tendon is exposed within the joint. The structures cut through in clearing the humeral head have been enumerated above, in connexion with amputation at the shoulder-joint. It must be remembered, while excising the head, that four- fifths of the growth in length of the humeral shaft takes place at the upper epiphyseal line, and that care must therefore be taken to avoid damage to that line in the young. CHAPTER XII THE ARM THE arm, upper arm, or brachial region is con- sidered to extend from the axilla above to the region of the elbow below. Surface anatomy. In women, and in those who are fat, the outline of the arm is rounded and fairly regular. It is less regular in the mus- cular, in whom it may be represented by a cylinder, somewhat flattened on either side* and unduly prominent in front (biceps muscle). The outline of the biceps muscle is distinct, and on either side of it is a groove. The inner of the two grooves is by far the more conspicuous. It runs from the bend of the elbow to the axilla, and indicates generally the position of the basilic vein and brachial artery. The outer groove is shal- low, and ends above at the insertion of the deltoid muscle. So far as it goes it marks the position of the cephalic vein. The insertion of the deltoid is an important landmark, and can^ be easily distinguished. It indicates very precisely the middle of the shaft of the humerus, is on the same level with the insertion of the .coraco-brachialis muscle, and marks the upper limit of the brachialis. It corresponds also to the spot where the cylindrical part of the humeral shaft joins the prismatic portion, to the point of entrance of the nutrient artery, and to the level at which the musculo- spiral nerve and profunda artery of the arm cross the back of the bone. When the arm is extended and supinated, the brachial artery corresponds to a line drawn along 275 276 THE UPPER EXTREMITY [CHAP. the inner border of the biceps, from the outlet of the axilla (at the junction of its middle and an- terior thirds) to the middle of the bend of the elbow. The artery is superficial, and can be felt in its entire extent. In its upper two-thirds it lies on the inner aspect of the shaft of the humerus, and can be compressed against the bone by pressure in a direction outwards and slightly backwards. In its lower third the humerus lies behind it, and compression, to be effectual, should be directed backwards. The superior ulnar collateral (inferior pro- funda) would be represented by a line drawn from fhe inner side of the humeral shaft at its middle to the back part of the internal or medial epicondyle. The nutrient artery enters the bone at its inner aspect opposite the deltoid insertion, and the inferior ulnar collateral (anastomotica magna) vessel comes off about 2 inches above the bend of the elbow. The ulnar nerve follows first the brachial artery, and then a line drawn from the inner side of that vessel, about the level of the insertion of the coraco-brachialis, to the gap between the inner condyle and the olecranon. The main part of the internal or medial cutaneous nerve of the fore- arm is beneath the inner bicipital groove, while the musculo-cutaneous nerve becomes superficial in the bend of the elbow at the outer margin of the tendon of the biceps in the outer bicipital groove or sulcus. Deep in this groove are found two nerves, the musculo-cutaneous and the musculo-spiral (radial), the first emerging from beneath the biceps, the second lying beneath and covered by the proximal part of the brachio- radialis. The skin of the arm is thin and smooth, especially in front and at the sides. It is very mobile, being but loosely attached _to the deeper parts by a lax subcutaneous fascia. In circular amputations of the arm this looseness of the integument allows it to be sufficiently drawn xn] BRACHIAL APONEUROSIS 277 up by traction with ;fchc hand only. It is from the integument covering the anterior surface of the biceps that the flap is fashioned in Taglia- cozzi's operation for the restoration of the nose. The fineness of the skin of this part, and its freedom from hairs, render it very suitable f9r this procedure. The scanty attachments of the skin of the arm allow it to be readily torn or stripped away in lacerated and contused wounds. Some- times in these lesions large flaps of integument are violently dissected up. The looseness of the subcutaneous tissues favours greatly the spread of inflammatory processes, while its comparative thinness allows of the early manifestation of ecchymoses. The limb is completely invested with a deep fascia, the brachial aponeurosis, ^ as by a sleeve. The fascia is held down at the sides by the two intermuscular septa which are attached along the outer and inner margins of the humerus, running from the deltoid insertion to the outer or lateral epicondyle on the one side, and from the coraco- brachialis insertion to the inner epicondyle on the other. By means of this aponeurosis and its septa the arm is divided into two compartments, which can be well seen in transverse sections of the limb (Fig. 63, p. 281). These compartments serve to confine inflammatory and hsemorrhagic effusions. The anterior of the two spaces has the less substantial boundaries, owing to the thinness of the brachial fascia as it covers the biceps. Effusions can readily pass from one compart- ment to the other by following the course of those structures that, by piercing the intermuscular septa, are common to both spaces : these are the musculo-spiral and ulnar nerves, the profunda artery, the superior and inferior ulnar collaterals. The principal structures that pierce the brachial aponeurosis itself are the basilic vein, a little below the middle of the arm, the internal cuta- neous nerve of the forearm, about the middle, and the external cutaneous nerve of the musculo- 278 THE UPPER EXTREMITY [CHAP. cutaneous, at the elbow. The two first-named are in the inner bicipital groove, and the last- named is in the outer. The brachialis is closely adherent to the bone, while the biceps is free. It follows, therefore, that in section of these muscles, as in amputa- tion, the latter muscle retracts more consider- ably than does the former. It is well, therefore, in performing a circular amputation, to divide the biceps muscle first, and then, after it has retracted, to cut the brachialis anticus. Brachial artery. The line of this vessel has already been given (see p. 275). It is well to note that in the very muscular the artery may be overlapped to a considerable extent by the biceps muscle. Compression of the brachial, unless per- formed carefully with the fingers, can hardly avoid at the same time compression of the median nerve. It must also be remembered that the in- ternal cutaneous ^ nerve lies in front of the vessel, or close to its inner side, until it pierces the fascia; that the ulnar nerve lies along the inner side of the artery as far as the coraco-brachialis insertion ; and that behind the commencement of the vessel is the musculo-spiral nerve. The venae comites are placed one on either side of the artery, and communicate frequently with one another by short transverse branches which directly cross the vessel, and which may give trouble in operations upon the artery. If in ligaturing the artery at its middle third the arm rests upon any sup- port, the triceps may be pushed up and mistaken for the biceps. If the ^ incisions be too much to the inner side the basilic vein may be cut, or the ulnar nerve exposed and mistaken for the median. Tillaux states that in the operation a large superior ulnar collateral artery has been taken for the brachial. Inasmuch as the median nerve often derives distinct pulsation from the subjacent vessel, it happens that in the living subject it has been confused with the main artery itself. xii] MUSCULO-SPIRAL NERVE 279 Abnormalities in the arrangement of the bra- chial artery are so frequent (they occur in 12 to 15 per cent, of arms) as to be of surgical im- portance. It is not unusual to find a collateral branch (vas aberrans) arising from the upper part of the brachial or lower part of the axillary, passing down the arm, superficially to the median nerve and ending in the radial or sometimes the ulnar artery. The vas aberrans may replace the brachial, in which case the artery will be found superficial instead of deep to the median nerve, and the profunda or deep artery and the superior ulnar collateral will arise from the remnant of the real brachial artery. This superficial brachial vessel may pass under the supracondyloid process, a hooked projection of bone which occasionally springs from the burner us, 2 inches above the internal epicondyle. It is situated among the inner fibres of origin of the brachialis. The iiins > iilo-s|>ir:il (radial) nerve, from its close contact with the bone, which it crosses at the level of the deltoid insertion, is frequently injured and torn. Thus, it has been damaged in severe contusions, in kicks, in stabs, in bites from horses, and very frequently in fractures of the humeral shaft; or the nerve may be sound at the time of fracture and become subsequently so involved in callus as to lead to paralysis of the parts it supplies. In a case reported by Tillaux, where paralysis followed some time after a fracture, the nerve was found embedded in callus, and on cutting some of the redundant mass away a good recovery followed. In several instances the nerve has been paralysed by the pressure of the head when a man has slept with his head Cresting on the arm in the position of full supination and abduction. It is said to be often paralysed in Russian coachmen who fall asleep with the reins wound round the upper arm. It has also been frequently damaged by the pressure of badly con- structed crutches, especially those that afford no proper support for the hand. Indeed, it is the 280 THE UPPER EXTREMITY [CHAP. nerve most often affected in "crutch paralysis," the ulnar being the trunk that suffers next in frequency. Fracture of the shaft of the humeriis is usually due to direct violence. The shaft may, however, be broken by indirect violence, and of all bones the humerus is said to be the one most frequently fractured by muscular action. As ex- amples of the latter may be noted the throwing of a ball, the clutching at a support to prevent a fall, and the so-called trial of strength known as " wrist-turning." Instances of muscular fracture of the humerus occur among soldiers while practising bomb-throwing. When the bone is broken above the deltoid insertion the lower fragment may be drawn upwards by the biceps, triceps, and del- toid, and outwards by the last-named muscle; while the upper fragment is drawn inwards by the muscles attached to the bicipital groove. When the fracture is below the deltoid insertion, the lower end of the upper fragment may be carried outwards by that muscle, while the lower frag- ment is drawn upwards to its inner side by the biceps and triceps. The deformity, however, as a rule depends much more upon the nature and direction of the force that breaks the bone than upon any muscular action. The displacements just noted may be met with, but usually they are quite independent of the relation of the deltoid insertion to the seat of fracture, and cannot be tabulated. The weight of the arm seldom allows of more than f of an inch of shortening. Fracture of a bone is always attended by a reflex contraction of the muscles surrounding that bone a reflex set up by injury to the sensory nerves which end in the damaged bone, periosteum, and musculature; hence the overriding of the broken ends. The reflex contraction ceases when the patient is anaesthetized, and the fragments, which could not be set before, can now be brought into apposition with ease. The humerus is more frequently the seat of xn] FRACTURES OF HUMERUS : NON-UNION 281 non-union after fracture than is any other bone. This result is quite independent of the position of the fracture in relation to the nutrient artery. Non-union and delayed union are entirely due to the difficulty in obtaining fixation or im- mobilization of the humeral fragments. Perfect immobilization to secure the rest necessary for repair can only be obtained by preventing all the muscles which act on any part of ~% . fc ,. the humerus from disturbing the site of fracture. Im- mobilization of the humeral muscles is obtained by fixing all the joints on which they act the shoulder-joint, the elbow -joint, the wrist- and hand- joints for muscles with a humeral attach- ment act on all of these joints. Fig. 63. Transverse sect Jon through Now, immobiliza- the middle of the arm. (Braime.) tion of the elbow, a , Biceps ; b. coraco-brachialis ; c, brachi- Wrist, and hand alis (anticus) ; rf, triceps ; 1, brachial artery : 2, median nerve : 3, ulnar IS easy, but no nerve; 4, musculo - spiral (radial) means have yet nerve, been devised which will keep the shoulder-joint at rest. Another cause would appear to be the entanglement of muscular tissue between the broken ends, for it must be remembered that the shaft of the bone is closely surrounded by adherent muscular fibres. Thus, in an oblique fracture the end of one fragment may be driven into the brachialis, while the other end projects into the substance of the triceps, and immediate contact of the bones may be consequently prevented. 282 THE UPPER EXTREMITY Amputation through the middle of the arm. The parts divided in a circular amputation are fully shown in Fig. 63. In the flap method there is a danger of transfixing the brachial artery. The artery, as may be seen from Fig. 63, be secured at the inner border of the biceps. In the anterior flap are included the biceps, the greater part of the brachialis anticus, with the musculo-cutaneous nerve between them, and a small piece of the triceps from the inner side of the limb. In the posterior flap are the triceps, any small part of the outer portion of the brachialis not included in the anterior flap, the superior profunda artery, and the musculo-spiral nerve. Growth of the humerus. About the seven- teenth or eighteenth year, growth ceases in the distal epiphyseal line, and the lower or distal epiphysis becomes united to the shaft. Growth ceases much later at the proximal or upper epiphyseal line, the proximal epiphysis joining with the shaft about the twenty-first or twenty- second year. With the closure of the epiphyseal lines, growth in length ceases. Digby has esti- mated that growth in length takes place four times more rapidly at the proximal than at the distal line. Hence injury to the proximal epiphy- seal line in a growing child will give rise to a much greater degree of shortening than a similar injury to the distal line. CHAPTER XIII THE REGION OF THE ELBOW Surface anatomy. On the anterior aspect of the elbow are seen three muscular elevations. One, above and in the centre, corresponds to the biceps and its tendon ; while, of the two below and at the sides, the outer corresponds to the brachio- radialis and the common extensor mass, and the inner to the pronator teres and the common set of flexor muscles. The arrangement of these elevations is such that two grooves are formed, one on either side of the biceps and its tendon. The grooves diverge above, and join the outer and inner bicipital grooves, while below they meet over the most prominent part of the tendon, and thus form together a V-shaped depression (Fig. 64). The distinctness of these details depends upon the thinness and muscular development of the individual. In the inner of the two grooves are to be found the median nerve, the brachial artery and its veins; while deeply placed below the outer groove are the terminations of the mus- culo-spiral (radial) nerve and profunda artery, with the small radial recurrent vessel. The biceps tendon can generally be felt distinctly. Its outer border is more evident than is its inner edge, owing to the connexion of the bicipital fascia (lacertus fibrosus) with the latter side of the tendon. Extending transversely across the front of this region is a crease in the integument, the ."fold of the elbow." This fold is not a straight line, but is convex below. It is placed some little way above the line of the articulation, and its lateral terminations correspond to the 283 284 THE UPPER EXTREMITY [CHAP. tips of the two epicondylar eminences. In back- ward dislocations of the elbow the lower end of the humerus appears about 1 inch below this fold, whereas in a fracture of the humerus just above the epicondyles the fold is either opposite to the prominence formed by the lower end of the upper fragment, or is below it. This crease is obliterated on extension. At the apex of the V-shaped depression, about the spot where the biceps tendon ceases to be dis- tinctly felt, and at the outer side of that tendon, the median vein divides into the median basilic and the median cephalic. At the same spot also the deep median vein joins the superficial vessels. The median basilic vein can be seen to cross the biceps tendon, to follow more or less closely the groove along the inner border of the muscle, and to join, a little above the internal (medial) epicondyle with the posterior ulnar vein to form the basilic trunk. The median cephalic, follow- ing the groove at the outer margin of the biceps, joins, about the level of the external (lateral) epicondyle, with the radial vein to form the cephalic vein. The brachial artery bifurcates 1 inch below the centre of a line drawn from one epicondyle to the other; the point of division is opposite the neck of the radius. "The coronoid process of the ulna can be indistinctly felt, if firm pressure is made in the triangular space in front of the joint" (Chiene). The points of the two epicondyles can always be felt. The internal epicondyle is the more prominent and the less rounded of the two. The humero-radial articula- tion is in a horizontal line, but the humero-ulnar joint is oblique, the joint surfaces sloping down- wards and inwards. Thus it happens that while the external epicondyle is only f of an inch (18 mm.) above the articular line, the point of the internal epicondyle is more than 1 inch (28 mm.) above that part (Paulet). From the obliquity of the joint surfaces between the ulna and humerus, it follows that the forearm, when in extension, is not in a xin] THE ELBOW-JOINT 285 straight line with the upper arm, but forms with it an angle that opens outwards. Thus, when traction is made upon the entire upper limb from the wrist, some of the extending force is neces- sarily lost, and such traction, therefore, should be applied from the elbow, as is the usual practice in reducing a dislocation of the shoulder by manipulation. A line drawn through the two epicondyles will be at right angles with the axis of the upper arm, while it will form externally a smaller angle with the axis of the forearm. Thus, if we look at the upper arm, the two epicondyles are on the same level, whereas, when viewed from the forearm, the inner epicondyle lies at a higher level than does the external process. The joint-line of the elbow is equivalent only to about two-thirds of the width of the entire line between the points of the two condyles (Fig. 66, p. 298). The prominence of the condyles forms a capital point d'appui for traction by encircling bands applied to the limb above the elbow-joint. At the back of the elbow the prominence of the olecranon is always to be distinctly felt. It lies nearer the internal than the external epicondyle. In extreme extension the summit of the olecranon is a little above the line joining the two condyles. When the forearm is at right angles with the arm, the tip of the process is below the line of the epicondyles, and in extreme flexion it lies wholly in front of that line. Between the olecranon and the inner epicondyle is a depression that lodges the ulnar nerve and the dorsal (posterior) ulnar recurrent artery. To the outer side of the olecranon, and just below the external epicondyle, there is a depression in the skin which is very obvious when the limb is extended. This pit is to be seen even in those who are fat, and also in young children. In it the head of the radius and radio-humeral joint can be felt, and can be well distinguished when the bone is rotated in pronation and supination. The pit corresponds to the hollow between the 286 THE UPPER EXTREMITY [CHAP. outer border of the anconeus and the muscular eminence formed by the two radial extensors of the carpus and the brachio- radialis. The highest point of the bone that can be felt moving on rotation will correspond to the radius immediately below the line of the elbow-joint, and is a valuable guide to that articulation. The upper limit of the elbow-joint reaches a line drawn between the point of the two epi- eondyles. The tuberosity of the radius can be felt just below the head of the bone when the limb is in the position of extreme pron- ation. The skin in front of the elbow is thin and fine, and is readily excoriated by tight bandaging and by \~, .:] improperly applied splints. The thinness of the skin Fig. 64. Left elbow allows the subjacent veins from in front. to be easily seen through a, Basilic vein ; Z>, cephalic the integuments, but the vein ; c, on the ulna, distinctness with which "Doints to in o(li tin iKisilic 11 i i vein ; d, on the radius, these veins appear depends point's to median cephalic mainly upon the amount of vein; e, radial vein;/, qil ^ nil f nT1r , mi a -fof J n ^ n median vein; g, posterior SUDCUtaneOUS lat. In tfie ulnarvein. The brachial very stoilt^ they may be divides into its radial and be difficult Or impossible to ulnar branches to the render them evident by the nTck. Side f the mdial llsual means adopted in venesection. The arrangement of the superficial veins in front of the elbow, so as to form an M -shaped figure, is familiar, but it must be confessed that xm] MEDIAN VEIN 287 it is by no means constant (Fig. 64). So far as I (F. T.) have seen, it would appear that the precise M-like arrangement figured in most books is only present in about two-thirds, and perhaps in only one-half, of all cases. The median vein breaks up into the median cephalic and median basilic, just to the outer side of the biceps tendon, and, therefore, the latter vein passes in front of the tendon, of the brachial artery and its veins, and of the median nerve. From these structures it is separated by the bicipital fascia. The median basilic vein may cross the brachial artery abruptly, and be com- paratively free of it, except at the point of ^cross- ing, or it may run for some distance quite in front of the artery, or, crossing it early, may He parallel with the vessel, although at a different level, for the greater part of its course. As re- gards size, the median basilic is usually the largest of these veins, the median cephalic coming next, and the median itself third, while the ulnar and radial veins are the smallest of the series. These veins are liable to many abnormalities, some of the most conspicuous being in cases where the main arteries of the part^also are abnormal. The deviation is more usual in the veins -on^ the radial than in those on the ulnar side of the limb. Thus it is common for the radial or the median cephalic veins, or both, to be either very defec- tive or entirely absent. In spite of the relation the median basilic vein bears to the brachial artery, it is nevertheless the vein usually selected in venesection and transfusion, and the intravenous injection of sera and vaccines. The reasons for its selection are these : ifc is usually the largest and most prominent of the veins, and the one the nearest to the surface; it is also the least movable vein, and the one the least subject to variation. The bicipital fascia forms an excel- lent protection to the brachial artery during phlebotomy. The density of that membrane varies, and depends mainly upon the degree of 288 THE UPPER EXTREMITY [CHAP. muscular development. In thin subjects the median basilic vein may receive pulsations from the subjacent artery. According to one observer, the walls of this vein are often as thick as those of the popliteal vein. The ulnar, radial, and median veins seldom yield enough blood on vene- section, since they are below the point of junction of the deep median vein, and thus do not receive blood from the deep veins of the limb. The brachial artery has, as may be supposed, been frequently injured in bleeding; and at the period when venesection was very commonly practised, arterio-venous aneurysms at the bend of the elbow were not infrequent. Since the principal super- ficial lymphatic vessels run with these veins, and since some of them can scarcely escape injury in phlebotomy, it follows that an acute lymphan- gitis is not uncommon after the operation, especi- ally when, the point of the lancet being unclean, septic matter is introduced into the wound. The internal cutaneous nerve (medial cuta- neous of forearm), which usually runs in front of the median basilic vein, may be wounded in bloodletting from that vessel. The injury to the nerve, according to Tillaux, may lead to " traumatic neuralgia of extreme intensity, and very chronic." A " bent arm " may follow after venesection, and Hilton believes this to be often due to injury to the filaments of the musculo-cutaneous nerve, especially to the inclu- sion of those filaments in a scar left by the opera- tion. The cutaneous branches of this nerve lie over the median cephalic vein. These peripheral fibres being irritated, the muscles which are sup- plied from the same segment of the cord (biceps and brachialis) are caused to contract by reflex action. Hence the bent arm. In one case Hilton cured a bent arm following bleeding by resecting the old scar, which on removal was found to have included within its substance some nerve filaments. There is a lymphatic (siipracubital) gland xmj BRACHIAL ARTERY 289 situated over the internal intermuscular septum of the arm, and just above the internal epicondyle. It receives some of the surface lymphatics from the inner side of the forearm and two or three inner fingers. In position it is the lowest of the constant glands in the upper limb. In the same position occurs an occasional bony out- growth of the inner aspect of the humerus the supracondyloid process. The brachial artery, and also the median nerve, may pass beneath and internally (medially) to this process. Brachial artery* In forcible flexion of the limb the artery is compressed^ between the mus- cular masses in front of the joint, and the radial pulse is much diminished or even checked. The artery may divide in the lower third of the arm, and in such cases the ulnar artery may pass over the bicipital fascia. Aneurysms at the bend of the elbow have been treated by flexion of the limb, that position bringing more or less direct pressure t9 bear upon the sac. In full extension of the joint the artery becomes flattened out, and the radial pulse diminished. In the over- extension possible with fractured olecranon the pulse may be stopped at the wrist. Forcible ex- tension of an elbow that has become rigid in the bent position has caused rupture of the brachial artery. The uliiar nerve is, from its position at the elbow, very liable to be injured. It passes in a groove behind the internal epicondyle, and is crossed by a bridge of fibrous tissue which pre- vents its displacement. The nerve may pass in front of the internal epicondyle, and an instance is reported where the nerve slipped forwards over that eminence whenever the elbow was bent (Quain). In exposing the ulnar nerve (for nerve- stretching, etc.) behind the elbow the nerve may be found quite covered by an occasional muscle, the epitrochleo-anconeus. The elbow-joint. The strength of this joint depends not so much upon either ligaments or 290 THE UPPER EXTREMITY [CHAP. muscles as upon the coaptation of the bony sur- faces. The relations of the olecranon and coronoid processes to the humerus are such that in certain positions the strength of the joint is very con- siderable. The elbow, being a pure hinge-joint, permits only of flexion and extension. These movements are oblique, so that in flexion the forearm in- clines inwards, carrying the hand towards the middle third of the clavicle. m If it were not for the obliquity of the joint line it would be possible for the hand to be placed flat upon the shoulder of the same side; but this movement is only pos- sible after some excisions of the joint, for in this operation the oblique direction of the articular surfaces is not reproduced. In extreme extension the ulna is nearly in a straight line with the humerus as regards their lateral planes, while in extreme flexion the two bones form an angle of from 30 to 40. Bursse. Of the bursse about the joint the large subcutaneous bursa over the olecranon is very commonly found enlarged and inflamed (Fig. 65), and when inflamed may lead to exten- sive mischief in the limb. Its enlargement is favoured by certain employments involving pres- sure on the elbow; thus, the disease known as "miner's elbow" is merely an enlargement of this sac. There is a bursa between the biceps tendon at its insertion and the bone, the relations of which to the nerves of the forearm are worth noting. A case, for instance, is reported where this bursa became chronically enlarged, and by pressing upon the median and dorsal interosseous nerves produced loss of power in the forearm (Agnew). There is a small bursa at the insertion of the triceps (Fig. 65). Of the ligaments of the elbow- joint, the an- terior and posterior are comparatively thin, and the latter especially soon yields to the pressure of fluid within the joint in disease of the articu- lation (Fig. 65). The internal lateral (ulnar XIII] LIGAMENTS OF ELBOW-JOINT 291 collateral) ligament is the strongest and most extensive of the ligaments of the part. From its rigidity, its extended attachment, and the fact that it serves to limit not only flexion and extension, but also any attempt to wrench the forearm laterally from the arm, it happens that it is the ligament that suffers the most often in "sprains" of the elbow. As this ligament is attached to the whole length of the inner border TR. i c E PO /1UMERU5 BICEPS BRACMIALIS AM CAPSULE SUP. L.O/1CU5. EPIPAIYSIS