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Those too large to be entirely included in one exposure are fi'med beginning in the upper left hand corner, left to right and top to bottom, as many frames as required, ^ha following diagrams illustrate the method: Les cartes, planches, tableaux, etc., peuvent dtre film6s d des taux de reduction diffdrents. Lorsque le document est trop grand pour dtre reproduit en un seul clichd, il est film6 A partir de Tangle supdrieur gauche, de gauche d droite, et de haut en bas, en prenant le nombre d'images n^cessaire. Les diagrammes suivants illustrent la m^thode. 1 2 3 1 2 3 4 5 6 I "Hf Equine Myology. BY A. H. KING, V.S TORONTO : J A. CARVETH & CO , MEDICAL PUBLISHERS. rSgi Entered according to Act of Parliament of Canada, in the year one thousantl eight hundred and ninety, by J. A. Carvi^th & Co., in the office of the Minister of Agriculture. ^^^^^S in ac( that b We ar with tl ones 1( work, Ml by no in sucl import; M; in corr PREFACE I ^EVERAL years' experience as a teacher of equine myology has convinced us that the great difficuUy that students experience in acquiring a good knowledge of the subject arises from the fact that beginners almost invariably attempt to master too many details. We are satisfied that if the principal origin and insertion, together with the action, were first fixed on the mind, and the less important ones left to be gradually acquired in the dissecting room by practical work, the result would be more satisfactory. Most of the facts recounted in this little hand-book, though by no means original, have been verified by the author, and arranged in such a way as to enable students to grasp at once the most important pointj. My best thanks are due Mr. E. B. Holmes for his assistance in correcting the proofs. A. H K gff^^ \ ^'«»WPw?«''(twf'"'.»K''-'!*t"'»'';f''''" ijj jiy,* M^mi- WM^— ^"W \ h whic irrita and I with ] the V tract eithe: fascji exclu find c Ihey fibroi 1 |issue ] into 1 ] r I EQUINE MYOLflGY. Myology is that branch of descriptive anatomy which treats of the muscles. , A Muscle is an organ capable of contracting when irritated chemically or by nerve stimulus. There are two varieties of muscular tissue, striated and non-striated. Striated Muscles are under the control of the will, with one exception, and are connected with bones, cartil- age, ligaments, or skin. Non-Striated Muscles are not under the control of the will ; this kind of muscle is found forming the con- tractile coats of the stomach, bladder, etc. Striated muscles are attached to other structures either directly or by means of tendons, aponeuroses or fesciae. Tendons are white cords or bands, formed almost exclusively of white fibrous tissue. They are inelastic lind connect the muscular tissue with the parts on which they act. Aponeuroses are membranous expansions of white fibrous tissue serving similar purposes to a tendon. I Fasciae. — They are laminae of fibrous or fibro-areolar tissue insheathing or serving to divide and attach muscles. J Muscles are divided according to their absolute form Into long, wide and short. Long Muscles are found principally in the limbs. 6 EgUINE MYOLOGY. Wide Muscles are found immediately beneath the " skin or around the great cavities. Short Musxles. — These arj found particularly around short bones. Muscles are sometimes named according to the arrangement of their fibres. In some they run longitud- inally with a tendon at either end. A Pennifprm Muscle is one in which the fibres converge, like the plumes of a feather, to one side of a tendon which runs the entire length. A Bi-Penniform is one in which the fibres converge from both sides of a tendon. Radiating Muscles where the fibres converge from a broad surface to a tendinous point. Digastric Muscle is one with the tendon in the centre. The origin of a muscle is the most fixed and central point from which the muscle acts. The insertion is the movable point to which the muscular force is directed ; but in many muscular acts the part usually described as the insertion becomes the fixed , point, and the origin the movable one. PANNICULUS CARNOSUS. This muscle is thin and sub-cutaneous, and covers the greater part of the body. It is divided into four por- tions, viz : — Facial, Cervical, Thoracic, and Abdominal. The Facial is thin and passes from the angle of the mouth over the masseter muscle to the zygoma. The Cervical IS attached posteriorly to the cariniform cartilage and is | fleshy ; anteriorly it extends into the intermaxillary space. | Laterally, above the levator humeri it is aponeurotic and | blends with the funicular portion of the ligamentui nuchae. i Ix \ i g ' ll«!.J..'lL.-„^- y beneath thel « particularlyj f rding to the run longitud- i ch the fibres one side of a I bres converge f ;on verge from sndon in the * d and central | ■o which the uular acts the mes the fixed 1 , and covers nto four por- tbdominal. >uth over the tilage and is ciliary space, t neurotic and I ligamentum » mg poj the pei ma dev vis ;in fri I- -H I I EQUINE MYOLOGY. The Thoracic portion is attached superiorly to the highest point of the withers ; inferiorly to the point cf the elbow. i The Abdominal jportion, like the cervical, is well developed ; it is attached anteriorly to the infernal trochanter of the humerus ; pos- teriorly to the stifle and fascia of the thigh. Action It corrugates the skin. I THE ABDOMINAL REGION. This region consists of a single group of four muscles, which are in pairs : External Oblique. Rectus Abdominis. ^j k ternal Oblique. Transversalis Abdominis. I The Abdominal Tunic. "* A broad sheet of yellow elastic tissue is found cover- ing this group of muscles. It is thickest in the centre and posteriorly becoming thinner as it proceeds outwards over |he External Oblique. Posteriorly it furnishes the sus- pensory ligaments of the sheath in the male, and slips to mamnary gland in the female. It is exceedingly well developed in the ox. It serves to support the abdominal rjscera and take the strain oiT of the abdominal muscles. The Linea Alba, white line, is a fibrous cord extending from the Ensiform Cartilage to the Pubes. It is formed by the ipterseclion of the aponeurosis of abdominal muscles, and |iasses over the centre of the abdominal cavity. The tme common or prepubian tendon is sometimes given to e insertion of the Linea Alba. External Oblique. (Obliquus Externus Abdominis ) Origin It is attached to the outer surface of the 14 last ribs from their centres to their cartil- ages, the anterior slips interdigitating with serratus magnu&. w. • I: 8 EQUINE MYOLOGY. Insertion To Linea Alba, Common Tendon, and ex- ternal angle of the Ilium. Note.— Posteriorly the aponeurosis of the external oblique appears to divide into two parts, one descend- ing on the internal muscles of the thigh to constitute the crural aponeurosis ; the other reflected upwards forming Poupart's ligament or crural arch, which is • attached by its extremities frorn the symphysis pubes to the external angle of ilium ; the upper edge is lost on the sublumbar muscles. The external inguinal ring lies in the angle formed by Poupart's ligament and the common tendon and is simply an opening through the external oblique. The crural ring is a triangular orifice behind Poupart's ligament. Internal Oblique. Origin From the external angle of the ilium. Insertion To the linea alba, last rib, and its fellow of the opposite side. Rectus Abdominis. Origin From the ensiform cartilage of the sternum. Insertion To the symphysis pubis, also to the linea alba throughout its whole extent. Transversalis Abdominis. Attachments Superiorly to the transverse processes of the lumbar vertebrae and the inner surface of the cartilages of the false ribs ; inferiorly to the linea alba, and by the common tendon to the sym.physis pubis. Action Of the abdominal muscles. They assist in the passage of urine, faeces, and in parturi- tion and difficult breathing. The rectus flexes the spine. With this group we may rightly include another small muscle. The Retractor of the Last Rib. (Unimportant.) Origin From the transverse processes oi the first four lumbar vertebrae. mm don, and ex- of the external rts, one descend- gh to constitute fleeted upwards arch, which is ymphysis pubes 2r edge is lost on nguinal ring lies [ament and the ling through the riangular orifice mm. its fellow of the sternum, he linea alba cesses of the ;r surface of s : inferiorly common he ey assist in i in parturi- The rectus itly include )i the first [ f EQUINE MYOLOGY. 9 Insertion To the posterior border of the last rib. Action To assist in expiration by drawing back and fixing the last rib. CERVICAL REGION. This region comprises all the muscles grouped around the cervical vertebrae. They are divided into two groups, Superior and Inferior Cervical. ftE ^Superior Cervical. Ti'apezius cervicalis Khomboideus longus Splenius Tracbelo mastoideus Complexus major Rectus capitus posticus major Rectus capitas posticus minor Obliquis capitis posticus Obliquis capitis anticus Spinalis colli Intertransversalis colli frigin Insertion potion Origin Insertion Action Origin Insertion Trapezius Cervicalis. From funicular portion of ligamentum nuchae as high as the third cervical vertebra. To tubercle on spine of the scapula. To elevate and draw the shoulder forward. Rhomboideus Longus. From funicular portion of ligamentum nuchae as high as the 2nd cervical. To inner surface of anterior angle of the scapula and cartilage of prolongation. To elevate and draw the scapula forward. Splenius. Superiorly it is attached to the ligamentum nuchae as far forward as the crest of the occipital, and back as far as the fifth dorsal spine. Inferiorly it digitates and is inserted to mas- toid crest, wing of the atlas, transverse processes of the second, third, and fourth cervical vertebrae. f .' i 10 EQUINE MYOLOGY. Action With its fellow, it elevates the head ; alone, it draws it to one side. Trachelo Mastoideus. Origin From the transverse processes of the first two dorsal and oblique processes of the last five cervical. Insertion By two tendons, one to the wing of the atlas, the other to the mastoid crest. Action With its fellow, to elevate the head ; alone, to draw it to one side. Complexus Major. Origin From the transverse and spinous processes of the first five dorsal and the oblique pro- cesses of all the cervical. Insertion To the occipital tuberosity. Action To extend the head. Rectus Capitis Posticus Major. Origin Spine of dentata. Insertion To the occipital. Action Extends the head. Rectus Capitis Posticus Minor. Origin From supero-antenor part of atlas. Insertion To the occipital tuberosity. Action To assist the major. Obliquis Capitis Posticus. Origin From the side of the superior spine of the axis. Insertion To wing and body of the atlas. Action Rotates the head. Obliquis Capitis An^icus. Origin From wing of atlas. Insertion To the occipital. Action It inclines the head on the atlas, and slightly extends it. niiiil ad ; alone, it the first two 'the last five of the atlas, ead ; alone. processes of oblique pro- pine of the nd slightly :.-f li^liMliPi -m EQUINE MYOLOGY. 11 Origin Insertion Action Spinalis Colli. (Scmispinalis Colli). This muscle consists of five bundles. From the oblique processes of the last five cervical vertebrae. To the superior spines of ail the cervical vertebrae, except the first and seventh. Acting together, the right and left muscles will extend the cervical portion of the spinal column ; singly they rotate and incline it to one side. Intertransversalis Colli. Consists of five bundles. Origin From the oblique process of one cervical vertebrae. Insertion To the transverse process of the vertebrae in front. Action To bend the neck to one side. -^Inferior Cervical Group. Levator humeri. Rectus capitus anticus major. Sterno maxillaris. Rectus capitus anticus minor. Sterno-thyro-hyoideus. Rectus capitus lateralis. Subscapulo-hyoideus. Scalenus. Longus Colli. Levator Humeri {2). (Mastoido Humeralis). Origin From the crest of the occipital, mastoid pro- cess and crest of the temporal, attached to the wing of the atlas, transverse processes of the second, third and fourth cervical vertebrae. Insertion To the deltoid ridge of the humerus. lection It extends and rotates the shoulder joint. When the limb is fixed it draws the head to one side. 4 12 Origin Insertion Action Origin Insertion Action Origin Insertion Action Origin Insertion Action Origin Insertion Action Origin Insertion Action EQUINE MYOLOGY. Sterno Maxillaris (2) From the cariniform cartilage of the sternum. To the angle of the inferior maxillary bone. Tu flex the head when acting with its fellow ; singly to incline it to one side Note. — These muscles are in contact in the lower half of the neck. Sterno-Thyro-Hyoideus (2). From the cariniform cartilage of the sternum. To the thyroid cartilage and body of the hyoid bone. It draws down the base of the tongue and larynx. Note.— This is a digastric muscle ; below the central tendon the two muscles are in intimate relation ; above they separate, forming a sling for the trachea. Subscapulo-Hyoideus. From the fascia covering the subscapularis muscle. To the hyoid bone. It depresses the hyoid apparatus. Rectus Capitus Anticus Major. From the transverse processes of the third, fourth and fifth cervical vertebrae. To the basilar process of the occiput. With its fellow, it flexes the head downwards; when acting alone, it draws it to one side. Rectus Capitus Anticus Minor. From the lower part of the ring of the atlas. To the basilar process of the occiput. It assists in flexing the head. Rectus Capitus Lateralis. From the inferior part of the atlas. To the styloid process of the occiput. To assist the preceding muscles. J* he sternum, lary bone, h its fellow ; t in the lower :he sternum, of the hyoid tongue and low the central ■elation ; above :hea. ibscapularis f the third, ae. put. downwards; o one side. 3f the atlas, put. s. put. n hitnit^ Ms EQUINE MYOLOGY. 18 I Origin Insertion Action Origin Insertion Action Scalenus.' From the transverse processes of the four last cervical vertebrae. To the upper third of the first rib. When the first rib is fixed together thes*^ muscles extend the neck each turns it to one side. is fixed, by drawing the assists in inspiration. acting singly, When the neck rib forward it Longus Colli. From the inferior surface of the bodies of the first six dorsal and last six cervical. To the tubercle of the atlas. It flexes the neck downwards. PECTORAL REGION. ' In this region there are two groups, the pectoral and the sternal. Pectoral Group. Anterior superficial pectoral Posterior superficial pectoral. Anterior deep pectoral. Posterior deep pectoral. Anterior Superficial Pectoral. (Pcctoralis Anticus.) Origin From the cariniform carjtilage and first bone of the sternum. Insertion To the deltoid ridge of the humerus. Action To adduct the arm. Posterior Superficial Pectoral. {Pectoralis Transversalis.) Origin From the greater part of inferior border of the sternum. Insertion To the deltoid ridge of the humerus and the fascia on the inner surface of the fore-arm. Action To adduct the arm. 14 EQUINE MYOLOGY. Orifiin hisertion Action Origin Insertior Action A' terior Deep Pectoral. [Pectoralis Parvus.) From the side of tae anterior half of the sternum ; cariniforjn cartilage, and cartii- ap^es of the first four ribs. To the fascia of the antea spinatus. It draws the shoulder backwards and down- wards. Posterior Deep Pectoral. (Pectoralis Magnus) From the posterior half of the sternum, abdominal tunic, ensiform cartilage and car- tilages of the tour last true ribs. To the inferior prominence of the internal trochanter of the humerus. To pull the shoulder joint, and thus draw the whole limb backwards. Sternal Group. Consists of two muscles : Lateralis sterni. Triangularis sterni. Later&Iis Sterni. Oriirin From the outer surface of the first rib. Insertion To the fourth segment of the sternum. Action It assists in expiration. Triangularis Sterni. Ontrin From the superior sternal ligament and seg- ments. Insertion To the cartilages, and inner surfaces of the distal ends of the true ribs, except the first. Action To assist in expiration. VsUBLUMBAR REGION. Consists of a single group. Psoas magnus. liiaciis. i'soas parvus vjuadratus lumborum I I T half of the Sfe, and cartil- itus. ds and down- the sternum, tilage and car- bs. f the internal thus draw the 5terni. rst rib. srnum. nent and seg- irfaces of the cept the first. tnborum • ( PPUPf P»f5^^**"» ."" iHHW"**!!!'-!' ("i^'JVJmSRtllWlillJ'liJ^lf 1 "tIkW ! y»»'"»WJ!' "'fwjpp^piw^wpf^ppfp tgtn Insertion Action Origin insertion Action Origin Insertion Action Origin iftsertion 1 Ictton EQUINE MYOLOGY. Psoas Magnus. 15 From the under surface of the last two ribs, the bodies of last two dorsal, and the trans- verse processes of all the lumbar vertebrae, except the last. To the small internal trochanter of the femur. When the spine is fixed to flex and rotate the femur outwards; when the femur is fixed to flex the spine. Psoas Parvus. From the bodies of last four dorsal, and all the lumbar vertebrae. To the ilio-pectineal eminence. To flex the pelvis on the spine, when both muscles act ; if the pelvis is fixed to arch the back. Iliacus. From the venter surface of the ilium outside its union with the sacrum. To the internal trochanter of the femur, with psoas magnus. To flex the femur. Note. — Posteriorly this muscle is grooved for the passage of the tendon of the psoas magnus. QuadratuB Lumbomm. From the inferior sacro-iliac ligament. To the tips of the lumbar transverse processes, and to the last rib. To assist in respiration and lateral flexion of the lumbar vertebric. K DIAPHRAGM. This J, iiiis is a very important muscle, separating the Woracic from the abdominal cavity. It is divided into o portions, a flat and fleshy: f 16 EQUINE MYOLOGY. 11 i 1 Attachments The flat, or main, portion is attached to the ensiform cartilage of the sternum, and the cartila^'es of the twelve last ribs. It is composed of muscular tissue on the outside and is tendinous in the centre. The fleshy portion, or pillars, the left of whic^ is the smaller, run back along the bodies oi the lumbar vertebrae, to which they are attached. Action It is the great muscle of inspiration. Foramina Foramen dextrum, below and to the right, foi the passage of the posterior vena cava. Foramen sinistriim, is to the left, for the pas sage of the oesophagus and pneumogastrie nerve. Hiatus Aorticus, between the pillars — for the passage of the posterior aorta, vena azygc and thoracic duct. I MUSCLES OF THE FORE LIMB. These are divided into four principal regions : - Shoulder or Scapular. Arm or Brachial. Fore-arm or Antibrachial Foot or Metacarpal. The shoulder or scapular cornprises two groups, ac external and an internal. External Scapular Group. Antea-spinatus Deltoid. Postea-spinatus, Teres Minor. Antea Spinatus Origin Antea-spinatus, fo^sa as high as the cartilagt of prol ngation. Insertion By two tendons, one to the summit of the external trochanter, and one to the summii of the internal trochanter of the humerus Action To extend the humerus on the scapula. Lttached to the jrnum, and the St ribs. It is on the outside e. le left of whic^, g the bodies ol 'hich they art ation. o the right, foi vena cava, ft, for the pas pneumogastric >iliars — for the a, vena azygc IB. igions wo groups, ar s the cartilagt summit of tht to the sumniii : the humerus scapula. 'W!WIPPifi>ll^BPWI^??'«flW!WP' EQUINE MYOLOGY. 17 •n tn Insertion ^(. Insertion Action tgtn Insertion Action Origin Insertion ction Origin Insertion Action 2 Postea-spinatus. Postea-spinatus, fossa as high as the cartilage of prolongation. By two tendons, one to the convexity of the external trochanter of the humerus, the other passes over the convexity and is in- serted to the deltoid ridge. To abduct the humerus. Deltoid (Teres Externum.) It IS in two portions, one originates from the tubercle on the spine of the scapula, and the other from the posterior angle. To the deltoid ridge of the humerus. To abduct and rotate the humerus outwards, and flex the shoulder joint. Teres Minor. {Postea Spinatus Minor.) From the posterior border of the scapula and the ridges in the lower part of the postea spinatus fossa. To the deltoid ridgt above its tubercle. Same as the deltoid. INTERNAL SCAPULAR GROUP. Subscapularis. Subscapularis fossa. To the posterior prominence of the internal trochanter of the humerus. To adduct the arm. Teres Internus. {Teres Major.) From the posterior angle and border of the scapula. The internal tuberosity of the humerus. To adduct and rotate the humerus inwards, and flex the shoulder joint. 18 EQUINE MYOLOGY. Scapula Humeralis Posticus. Origin From the posterior part of the scapula, jusi above the glenoid cavity. Insertion To the posterior part of the humerus immedi ately below the head. Action To render tense the capsular ligament of the joint. THE BRACHIAL REGION Comprises two groups, anterior and posterior. Anterior Brachial Group. yFlexor-brachii. / Coraco-humeralis. Humeralis-obliquus. Flexor Brachii. {Biceps, long Flexor of Fore-arm.) Coracoid process of the scapula. To the bicipital tuberosity of the radius. To flex the fore-arm on the arm. It also has a slight extension action on the shoulder joint. Note. — This muscle is very important ; after leavins the coracoid process of the scapula, it passes througt the bicipital groove of the humerus. It is tendinom here, and has a large synovial bursa interposed ; belov this it has a large fleshy belly, which passes over the anterior surface of the humerus. Coraco Humeralis. From the coracoid process of the scapula. By two tendons, one to the internal, and the other to the anterior surface, of the humerus. To adduct and flex the shoulder joint. Humeralis Obliquus. (Brachialis Anticus). From the posterior surface of the humerus just below the head ; passes down the mus culo-spiral groove. Origin Insertion Action Origin Insertion Action Origin ^ he scapula, just jmerus immedi ligament of the lor. ) ila. the radius. m. It also has n the shoulder 1^^ rtant ; after leaving , it passes through . It is tendinous interposed ; below ch passes over the the scapula. : internal, and surface, of the er joint. f the humerus down the mus ( 'f ft . 1^' »>' -M Hi EQUINE MYOLOGY. 19 Insertion Action Origin Insertion Origin Insertion Origi n Insertion Action Origin Insertion Action Origin Insertion Action It is inserted to the radius immediately below the bicipital tuberosity ; also to the ulna. To flex the elbow joint. POSTERIOR BRACHIAL GROUP. vTriceps extensor brachii. Scapulo-ulnaris. Anconeus. Triceps Extensor Brachii. Comprises : Caput magnum, Caput medium, Caput parvum. Caput Magnum. From the posterior border of the scapula. To the upper part of the olecranon. Caput Medium. From the supero-external part of the humerus. To the superior part of the olecranon. Caput Parvum. From the internal surface of the humerus, below the internal tubercle. To the olecranon They all extend the fore-arm upon the arm, and the magnum has a flexion action on the shoulder joint. Scapulo Ulnaris. From the posterior angle of the scapula. To the olecranon. To assist the caput magnum. Anconeus. From the borders of the olecranon fossa. To the anterior and external part of the ole- cranon. To tense the capsular ligament of the elbow joint. 20 EQUINE MYOLOGY, I: M !. i 1 I •t;! 'I ' ili ' ANTIBRACHIAL REGION, OR FORE-ARM. ^ ( Anterior Antibrachial Group. Comprises | posterior \ , Anterior Antibrachial Group. -^ • Extensor metacarpi magnus. Extensor metacarpi obliquus. Extensor Pedis. E^xtensor suffraginis. Extensor Metacarpi Magnus. {Anterior extensor of the Metacarpus.) Origin From the external condyle of the humeri) and capsular ligament of the elbow joint. Insertion To the supero-anterior part of the larg metacarpal. Action To extend the metacarpal bones. Extensor Metacarpi Obliquus. (Oblique extensor of the metacarpus.) Origin From the lower third of the external borde of the radius. Insertion To the head of the internal small metacarpa Action To aid the large extensor. Note. — It passes over the tendon of the magnus ar has a bursa interposed. Extensor Pedis. (Anterior extensor of the phalanges.) Origin It originates from the external condyle of tl; humerus, also attached to the extern. tuberosity and outer border of the radiu: insertion To the pyramidal process of the os pedis. '■ is also attached to the capsular ligament the fetlock joint, os suffraginis and corona Action To extend the interphalangeal joints, the ft lock and the carpus. Note. — Like the extensor metacarpi magnus, it h a large fleshy belly at its upper part. It becomes te: dinous about twc-thirds of the way down the radii RE-ARM. il Group. iS.) of the humeri] le elbow joint, rt of the larg mes. s. ts.) I external horde mall metacarpa 1 of the magnus ar rs.) al condyle of tli| to the externi ler of the radiui the OS pedis. ! •sular ligament i jinis and corona^ sal joints, the fe| icarpi magnus, it !i| art.* It becomes te- ivay down the radir I i n A EQUINE MYOLOGY. 21 The tendon is double, and passes through a groove on the antero-inferior part of the distal end of the radius, where it is bound down by the anterior annula» ligament. After emerging at the lower part of the ligament the two tendons separate, one going to join the extensor suifraginis, the main one passing down to the pyramidal process of the os pedis. In its course over the os suf- fraginis it is joined by the bifurcations of the suspensory ligaments. Extensor Suffraginis. {Lateral Extensor of the Phalanges.) Origin From two points ; one from the external tuberosit}' at the proximal extremity of the radius, and one from the ulna. Insertion To the supero- anterior part of the os suffra- ginis. Action It extends the digit. Note. — This muscle is small, and passes down the outer side of the radius through a groove in the external tuberosity at the distal extremity, and under the annular ligament ; upon emerging it is supported by a slip from the tendon of the extensor pedis, and one from the annular ligament. It then passes to the os suffraginis. POSTERIOR ANTEAERACHIAL GROUP. Flexor metacarpi externus. Flexor metacarpi medius. Flexor metacarpi internus. Flexor pedis perforatus. Flexor pedis perforans. Ulnaris accessorius. Radialis accessorius. Flexor Pedis Perforatus. (Superficial Flexor.) Origin From the internal condyle of the humerus. Insertion To the lateral sides of the os coronae. Action To flex the pastern and fetlock joints, and assist in flexing the carpus. Note.— The perforatus is more superficial than the 22 Origin Insertion Action Origin Insertion Action Origin EQUINE MYOLOGY. j„«n« as it approaches the coronse. Flexo. Pedis Perforans. ^Deep Flexor of the Phalanges.) M the eternal condyle of^^^^^^^^^ assists in flexing the latter. ^^^ N,,-,._This muscle i« ^^'^f [^^^rpl^'^ ^ - ^«"*^°^ becomes tendinous i"«\^b°rcarpalSth. About one- pas^s through the posterior c^^^^^ ,^^ ^eta- iTi way down the "^f^f^^h holds it in position carpal, or check l>g^^«f ( jS the incomplete arch At the fetlock it passers ^J^^^^jdens out before becom- formed by the ^^'^:'i^o^:irner^hr..^^^^^^^ Sferrin ^oU^ndons • - . th^^^^^^^^^^^ -rr;eSillorfoVteVo-s. Ulnaris Accessorius. ( Unimportant. ) From the posterior border and sumnut c 0,. ItSs°wUh the tendons of the pe,t.,.r near the cavpus. It assUts the flexor perforans. Flexor M.t.carpi Externus. (Exurnal f'-xo, of the mel«ca,t")' ' „ .u^ external condyle of the humerus and ^rps^^lar hpament of the elbow ,ou,t. lUUMiRUUi he ir- he ;h; ich Ips )er- ier, n it e OS and s, snd endon It one- meta- isition. e arch jecom- at the ik, also le there c/' ib*^ i'tl> »> erus and t. EQUINE MYOLOGY. 2» Insertion By two tendons, one to the superior border of the trapezium, and one to the external small metacarpal. Flexor Metacarpi Medius. (Oblique flexor of the metacarpus). Origin From the internal condyle of the humerus and the olecranon. Insertion To the trapezium. Flexor Metacarpi Internus. Origin From the interal condyle of the humerus. Insertion To the head of the internal small metacarpal bone. Action Tne action of the last three muscles is to flex the metacarpus on the radius. Radialis Accessorius. ( Unimportant) . Origin From the posterior part of the shaft of the radius. Insertion It joins the tendon of the perfoians. Action To assist the flexor perforans. METACARPAL REGION. This region consists of two pairs of exceedingly small muscles. •^1 i r Interossei Metacarpi. Lumbricales. (Unimportant). Interossei Muscles (a). These muscles are very slender, and art situated on the inner side of the small metacarpal bones. Origin From near the head of the small metacarpal. Insertion To the bifurcations of the suspensory liga- ment. 24 EQUINE MYOLOGY. Lumbricales (2). These muscles originate on either side of the perforans, just above the fetlock, and are lost in the coverings of the fetlock joint. COSTAL REGTON. Consists of a single group. Trapezius dorsalis. Rhomboideus brevis. Latissimus dorsi. Serratus magi. is. Transversalis costarum. Serratus anticus. Serratus posticus. External intercostal. Internal intercostal. Levatores costarum. Trapezius Dorsalis. Origin From the supraspinous ligament, extending from the highest point of the withers to the 12th dorsal vertebra. Insertion To the tubercle on the spine of the scapula. Action To draw the scapula upwards and backwards. Serratus Anticus. {Part of superficialts costarum.) Origin From the summits of the dorsal spines, from the ist to the 13th inclusive. Insertion It digitates inferiorly and is attached to the anterior border of the nine ribs succeeding the fourth. Action To assist in inspiration. Serra'ms Posticus. (Part of superficialis costarum.) Origin From the spinous processes vertebrae after the fourth, lumbar vertebrae. Insertion To the posterior border of the nine last ribs. Action To assist in expiration. External Intercostals. (17 pairs.) Origin From the posterior border of each rib. Insertion To the anterior border of each succeeding rib. Action They are inspiratory muscles. of the dorsal and to some ■s?*- ifii p ^jyiiawiM t'M i "^^w.w '«^^gvHM 7w^^a^g'^^r ^■^^! a?q?^g".?^' ^ !i: -f.-ii uamgi'iai EQUINE MYOLOGY. 25 Internal Intercostals. (17 pairs.) Origin and The same as the externals, but the fibres run Insertion downwards and forwards. Action They are expiratory muscles. Rhomboideus Brevis. Origin From the spines of the first five dorsal vertebrae. Insertion To superior part of the inner surface of the scapula and cartilage of prolongation. Action To draw the scapula upwards. Latissimus Dorsi. Origin It is attached superiorly to the supraspinous ligament from the highest point of the withers to the last lumbar vertebrae. Insertion To the internal tuberosity of the humerus. Action To flex the shoulder joint. Note. — This muscle is continuous posteriorly with the gluteal fascia. Serratus Magnus. Origin From the transverse processes of the five posterior cervical vertebrae and the ex- ternal surface of the eight true ribs from their middles to their cartilages. Insertion To the venter surface of the scapula between the origin of the subscapularis and the insertion of the rhomboideus brevis. Action To draw the scapula close to the body, and when the limbs are fixed it elevates the neck. Transversalis Costarum. Origin From the transverse processes of the first lumbar vertebrae, and the ribs near their angles. p k i 1 M 26 EQUINE MYOLOGY. Insertion To the external surface of all the ribs below the inferior border of longissimus dorsi, a tendon to each, and one to the last cervical vertebrae. Action It assists in expiration. Levatores Costarum, (17 pairs.) Origin From the transverse processes of the dorsal vertebrae. Insertion To the external faces of the ribs, just above their angles. Action It assists in inspiration. DORSO LUMBAR REGION. Consists of a single group. Longissimus dorsi. Semispinalis dorsi. Longissimus Dorsi. Origin From the crest and venter surface of the ilium ; the spinous and transverse processes of the first two bones of the sacrum : the spinous transverse and oblique processes of all the lumbar vertebrae ; the spinous and transverse processes of all the dorsal verte- brae ; the supraspinous ligament of the dorsal and lumbar regions, and the ribs as far outwards as their angles. Insertion To the transverse and spinous processes of the four last cervical vertebrae. Action It extends the spine and elevates the neck. ^lOTE. — Anteriorly the muscle divides into an inner and outer part, and between the two divisions, which are difficult to separate, the complexus major and trachelo-mastoideus originate. The inner portion, the spinalis dorsi of some writers, is attached to the supraspinous ligament as far back as the twelfth dorsal ,, .J, i--''. s^ :: a >- f.i!::_ ' K U5< iS >!/'.;■ ,'•■'»•,•■ iX' > 3 ^^f*v f . ^v» .. ^,^'4t EQUINE MYOLOGY. 27 vertebrae, and to the first six dorsal spines, and is in- serted into the spinous processes of the four last cervical. Semispinalis of the Back and Loins. (Semispinalis dorsi et lumborum). Origir From the sacrum, the oblique processes of all the lumbar, and the transverse processes of all the dorsal. Insertion To the spinous process of the third or fourth anterior vertebrae. Action The right and left muscies, acting together, extend the spme; singly, they are lateral flexors. COCCYGEAL REGION. This group contains four pairs of muscles : — Erector coccygis (2). Depressor coccygis (2). Curvator coccygis ;)• Compressor coccygis (2). Erector Coccygis. Attached To the upper part of the sacrum and coccygeal bones. Action When acting together, to elevate the tail ; singly, to draw it upwards and outwards. Depressor Coccygis. Attached To the under surface of the sacrum and coccygeal bones. Action To bend the tail downwards ; singly, to draw it to one side. Curvator Coccygis. Attached To the lateral side of the sacrum and coccy- geal bones. Action To curve the tail sideways. 28 Origin Insertion A ction Origin Insertion Action Origin Insertion EQUINE MYOLOGY. Compressor Coccygis. From the inner surface of the sacro-sciatic ligftment. To the last two sacral and first two coccygeal vertebrae. With its fellow, it forcibly depresses the tail ; singly, it draws it to one side. Muscles of the Posterior Limb. These form four principal regions : Gluteal. Femoral. Tibial. Metatarsal GLUTEAL REGION. This region comprises several muscles, viz : Gluteus externus. Obturator internus. Gluteus maximus. Obturator externus. Gluteus iuternus. Pyriformis. Rectus parvus. Gemellus anticus. Gemellus posticus. Gluteus E:;'.:ernus. (Superficial G luteus. ) This muscle has two origins, one from the spines of the sacrum, and one from the external angle of the ilium. To the trochanter mnor externus of the femur. To flex and abduct the femur. Gluteus Maximus. (Middle Gluteus.) From the tendinous envelope of the longissi- mus dorsi, upper surface of the ilium and sacro-sciatic ligament. By two tend — , one to the summit of the ' lilWtr- ' T"! '^T.^TT*!!'-^ *m .«li!'i •■■MH IC al be be be si- he Of Ac Or Im On Ins On Ins On Inst Orq EQUINE MYOLOGY. 29 A ction Origin Insertion Action Origin Insertion Origin Insertion trochanter major, and the other passes over the convexity and is inserted to a roughened ridge below, To extend the femur on the pelvis, and when the posterior limbs are fixed to assist in rearing. Gluteus Internus. (Deep Gluteus.) From the shaft of the ilium. To the hollow inside of the trochanter major of the femur. Abducts and rotates inwards the hip-joint. Rectus Parvus. From the rim of the acetablum. To the supero-anterior part of the femur. Obturator Externus. From the outside of the obturator foramen. In the trochanteric fossa. Obturator Internus. Origin From the inside of the obturator foramen. Insertion In the trochantc ic fossa. Pyriformis. Origin From two points, one from the transverse processes of the sacrum, and one from the inner surface of the shaft of the ilium. Insertion In the trochanteric fossa. Gemellus, Amicus, Posticus. Origin From the shaft of the ischium, one in front and one behind the conjoined tendon of the obturator internus and pyriformis. 80 EQUINE MYOLOGY. Insertion Action Origin Insertion Action Origin Insertion Action Origin Insertion Action Trochanteric fossa. The last six muscles rotate the limb outwards and help to abduct it. FEMORAL REGION. Divided into four groups : — Internal, External, Anterior, Posterior. Internal Femoral Group. Sartorius, Gracilis, Pectineus. Adductor brevis, Adductor longus, Adductor magnus. Triceps. adductor. femoris. Sartorius. {Long adductor of the leg.) From the iliac fascia near the tendon of the psoas parvus. To the internal straight ligament of the patella and supero-internal part of the libia. To adduct and flex the femur. Gracillis. (Short adductor of the leg.) From the itiferior surface of the ischo-pubio symphysis. To the internal straight ligament of the patella and supero-mternal part of the libia. To adduct the limb. Pectineus. From the inferior surface of the pubis by two tendons — one each side of the pubio-femoral ligament. To the internal border of the femur, near the nutrient foramen. To adduct and flex the femur. "wi/" jr*' Is EQUINE MYOLOGY. 81 Adductor Brevis. {Small adductor of the thigh.) Origin Superiorly from the inferior surface of the pubis. Insertion To the posterior surface of the femur — about the middle. Action To adduct and rotate the femur outwards. Origin Insertion Action Adductor Longus. {Great adductor of the thigh.) From the inferior surface of the ischium. By two tendons, one to the middle of the femur with the brevis, and one to the internal condyle. To adduct and rotate the femur outwards. Adductor Magnus. {Semi-tnenibranosus.) Origin From the coccygeal fascia and tuberosity of the ischium. Insertion To the internal condyle of the femur. Action To adduct the limb and extend the thigh. EXTERNAL FEMORAL GROUP. One muscle. Triceps Abductor Femoris. Origin From the spines of the sacrum, sacro-sciatic ligament and ischial tuberosity. Insertion By three divisions, one to between the two small trochanters of the femur, one to the patella, and one to the thigh by fascia. Action It abducts the entire limb ; the anterior half of the muscle expends the stifle and the posterior half flexes it. 82 EQUINE MYOLOGY. ANTERIOR FEMORAL GROUP. Tensor vaginae femoris. Vastus externus. Crureus. Rectus femoris. Vastus intemus. Tensor Vaginae Femoris. Origin From the external angle of the ilium. Insertion Into the fascia lata. Action It flexes the hip joint, and renders tense the fascia lata. Rectus Femoris. Origin From two depressions in front of the acetabu- lum. Insertion To the superior surface of the patella. Action To flex the hip joint and extend the stifle. Vastus Internus. Origin From the internal border and inner half ot the anterior surface of the femur. Insertion To the patella and is continuous with the internal straight ligament of the same. Action To extend the stifle. Vastus Externus. Origin From the external border and outer half of anterior surface of the femur. Insertion To the patella, and is continuous with the external straight ligament. Action To extend the stifle. Rectus Parvus. Origin From brim of the acetabulum. Insertion To the anterior and upper part of the femur. Action Tenses the capsular ligament of the hip-joint. the bu- F ot the ' of the lur. int. EQUINE MYOLOGY. POSTERIOR FEMORAL GROUP. Biceps rotator tibialis. Ischio femoral is. 38 Biceps Rofator Tibialis. (Semitendinosus). Origin From the spines of the sacrum, sacro-sciatic ligament, and ischial tuberosity. Insertion To the crest of the tibia. Action To flex the stifle and rotate the leg mwards. Ischio Femoralis. (Unimportant). Origin From the inferior surface of the ischium. Insertion To the upper third of the posterior surface of the femur. Action To extend and adduct the feinur. TIBIAL REGION. Divided into anterior and posterior groups. Origin Insertion Action 8 I Flexor metatarsi. Flexors. Anterior, i Extensor pedis. ( Peroneus. Extensor. Flexor Metatarsi. From a pit between the external condyle and trochlea of the femur. To the supero anterior part of the large metatarsal, the cuboid and small cuneiform. It flexes the tarsal joint. Note. —This is one o{ he most important muscles in the body, and is made up of a tendinous and a fleshy portion The tendinous portion arises as indicated above from the lemur. The fleshy portion, arises from the groove on the outer surface of the tibia. i 84 EQUINE MYOLOGY. Origin Insertion Action Origin Insertion Action Origin Insertion Action Origin Insertion Action Origin Extensor Pedis. From the pit between the external condyle . and trochlea of the femur. To the pyramidal process of the os pedis. To extend the entire digit and flex the tarsal joint. Note. — It is bound down by the anterior annular liga- ment. About one-half way between the hock and fet- lock it is joined by the tendon of the peroneus. Peroneus. From the head and body of the fibula. It joins the tendon of the extensor pedis. It assists the extensor pedis. POSTERIORTIBIAL REGION. Extensors. | Gastrocnemius externus. Flexors. Gastrocnemius internus. Flexor pedis perforans. 1 Flexor pedis accessorius. iPopliteus. Gastrocnemius Externus. From each side of the supracondyloid fossa. To the summit of the os calcis. To flex the stifle joint and extend the hock. Soleus, or Plantaris. From the head of the fibula. It joins the tendon of the gastrocnemius externus. It assists very slightly the gastrocnemius externus. Gastrocnemius Internus. In the supracondyloid fossa. It becomes tendinous and winds from within outwards -^.i'^' .4r \ V «^ • ^' ... :