A GUIDE 
 
 TO THE 
 
 Dissection of the Blood Vessels 
 
 and Nerves 
 
 OF THE 
 
 Pectoral and Pelvic 
 
 Limbs 
 
 OF 
 
 The Horse 
 
 BY 
 
 Grant Sherman Hopkins, 
 
 New York State Veterinary College at Cornell University, 
 Ithaca, N. Y. 
 
A GUIDE 
 
 TO THE 
 
 Dissection of the Blood Vessels 
 and Nerves 
 
 OF THE 
 
 Pectoral and Pelvic 
 
 Limbs 
 
 OF 
 
 The Horse 
 
 BY 
 
 Grant Sherman Hopkins, 
 
 New York State Veterinary College at Cornell University, 
 
 Ithaca, N. Y. 
 
 COPYRIGHT 1 9 14 
 BY GRANT SHERMAN HOPKINS 
 

 ©CI.Aa89109 
 
 OCT 29 1914 
 
PREFACE 
 
 Every teacher who has had experience with classes in Anatomy appre- 
 ciates the diffictilties that confront the student in his attempt to dissect 
 any portion of the body with only his text-book of Descriptive Anatomy, 
 for a guide. The present "Guide" has been prepared in the hope of assist- 
 ing students in the dissection of the blood-vessels and nerves of the pec- 
 toral and pelvic limbs. A knowledge of the muscles is presupposed. In 
 our experience, we have found it most desirable that, upon the completion 
 of a part, the student should demonstrate his dissection to the instructor 
 in charge. By no other means can the .student be brought to realize 
 more clearly the vast difference between studying and knowing the actual 
 object itself and the mere memorizing the description of it as given in 
 
 his text-book. . 
 
 G. S. H. 
 
Dissection of the Blood-Vessels and Nerves of 
 the Arm or Pectoral Limb 
 
 Cut the skin along the median Une from the xiphoid cartilage to a point 
 15 or 20 cm. cephalad of the presternum; also cut at a right angle to this 
 along the middle of the proximal half of the antebrachivini and reflect the 
 skin from the pectoral muscles. Note the large vein (V. cephalica) and the 
 small artery lying in the groove formed by the anterior superficial pectoral 
 muscle and the adjoining border of the M. mastoido-himieralis. Transect 
 the two superficial pectorals close to their sternal attachments. Now 
 dissect up the cervical panniculus, transect it a short distance from its 
 attachment to the sternum and turn it aside. Beneath this portion 
 of the pannicvilus is a mass of fatty tissue in which are numerous lymph 
 nodules — the Prescapular or superficial cervercal lymph gland. The full 
 extent of this gland may be seen when the M. mastoido-humeralis is turned 
 aside. Transect the mastoido-hiuneralis a little above (cephalad) the 
 point of the shoulder and turn it aside sufficiently to expose the underlying 
 prescapular portion of the anterior deep pectoral muscle and the prescapvdar 
 lymph gland. Do not disturb unnecessarily the gland for beneath it 
 are an artery and vein of some surgical importance. Trace the large 
 vein (V. cephalica) and the small artery (a branch of the A. cervicalis 
 inferior) that cross the anterior deep pectoral muscle in the groove between 
 this muscle and the mastoido-hiuneralis, in so far as the vessels are at 
 present accessible. Ligate and cut the vessels. Abduct the arm somewhat 
 and identify the two deep pectoral muscles. Transect the latter muscles close 
 to their attachment to the sternum. Abduct the arm a little and dissect 
 between the deep pectoral muscles and the thoracic wall until the large A. 
 and V. Axillaris are exposed. Carefully clean up the V. Axillaris noting 
 meantime the lymph glands, Posterior cervical or prepectoral, that lie 
 just cephalad or anterior to the V. Axillaris. Cut the vein in order clearly 
 to expose the A. Axillaris which lies immediately dorsal to it. Clean up 
 the A. Axillaris taking care not to cvit any of its branches or the nerves that 
 cross the ventral surface of the artery a short distance (4 to 6 cm.) from the 
 first rib. Cut the artery close to the rib. Occasionally a large vein lies 
 just anterior to the A. Axillaris; if so, this also should be cut. 
 
 A. cervicalis inferior arises from the axillaris nearly opposite the first rib. 
 Near the ventral border of the M. scalenus it divides into two nearly equal 
 branches — a ventral and a dorsal branch. The ventral branch crosses 
 
the superficial surface of the anterior deep pectoral and then runs in the 
 groove formed by this muscle and the mastoido-humeralis, as already seen, 
 and terminates in the mastoido-himieralis. Small branches are supplied 
 to the posterior cervical lymph glands, the cervical pannicultis, the stemo- 
 mandibularis, sterno-thyrohyoideus, anterior superficial pectoral and a 
 small branch to the region of the presterntun. The dorsal branch extends 
 antero-dorsally along the anterior border of the anterior deep pectoral 
 muscle. It passes beneath the prescapular lymph gland and between the 
 muscles subscapulo-hyoideus and mastoido-htomeralis to the latter of which 
 it is principally distributed. It also gives off branches to the anterior 
 deep pectoral muscle and to the posterior cervical and prescapular lymph 
 glands. 
 
 The ventral portion of the M. scalenus intervenes between the axillary 
 blood-vessels and the nerves that form the brachial plexus. The brachial 
 plexus is formed by the ventral divisions of the 6th, 7th and 8th, cervical 
 and the ist and 2d thoracic nerves, as will be demonstrated later. Cut 
 the dorsal branch of the A. cervicalis inferior and carefully remove the 
 connective tissue that surroimds the large nerve trtmks of the brachial 
 plexus. 
 
 N. phrenicus or diaphragmatic nerve originates from the ventral divisions 
 of the 6th and 7th cervical nerves ; occasionally it receives a small branch 
 from the 5th cervical also. The two or three radicals of the phrenic 
 nerve extend obliquely across the superficial face of the M. scalenus and at 
 its ventral border unite to form a single trunk, just as the nerve enters the 
 thorax, or a short distance within the thoracic cavity. Dissect up from the 
 surface of the scalenus the two or three radicals of the N. phrenicus. Im- 
 mediately after crossing the A. cervicalis inferior the N. phrenicus receives 
 a small communicating branch from the inferior cervical ganglion of the 
 sympathetic nerve. The course of the phrenic nerve through the thoracic 
 cavity to the diaphragm will be studied when the thoracic portion, of the 
 vagus and sympathetic nerves are traced. 
 
 Exposure of the brachial plexus and removal of the thoracic limb. 
 
 Expose as follows, the ventral divisions of the nerves that form the 
 brachial plexus, viz., the 6th (not constant), 7th and 8th cervical and the 
 I St and 2d thoracic. Cut the N. phrenicus at the first rib. Remove a 
 section of the ventral portion of the M. scalenus opposite the 6th, 7th, and 
 8th intervertebral foramina. Cut the skin and the Mm. panniculus 
 and latissimus, some distance (30 to 50 cm.) posterior to the scapula; cut 
 the skin and both portions of the trapezius close to the ligamentum nuchae; 
 
also cut the serratus magnus, and rhomboideus close to their attach- 
 ments to the scapula thus leaving the arm attached to the body only by 
 the nerves of the brachial plexus. Before attempting to expose farther the 
 ventral divisions of the 6th, if present, 7th and 8th cervical and the 
 1st and 2d thoracic nerves, first note on a skeleton the relation of the first 
 two ribs to the 6th, 7th and 8th cervical and the ist and 2d thoracic inter- 
 vertebral foramina, through which the above mentioned nerves emerge from 
 the spinal cord. Now place the arm in such a position that the whole of 
 the thoracic portion of the M. serratus magnus is exposed. Carefully 
 remove the small portion of the M. scalenus that lies dorsal to the brachial 
 plexus taking care not to cut any of the nerves. The large nerve to the 
 thoracic portion of the serratus magnus arises from the 7th and 8th cervi- 
 cals (or from the 8th only) and extends posteriorly on the surface of the 
 serratus magnus to which it is distributed. This nerve, more or less covered 
 by connective tissue, may emerge from between the dorsal and ventral 
 portions of the scalenus, or it may pass through the small dorsal portion of 
 the muscle. After tracing the nerve, cut it 15 to 20 cm. from its origin. 
 The ventral divisions of the 7th and 8th cervical nerves are readily exposed ; 
 the 1st and 2d thoracic nerves however, are covered by the ribs of which 
 the first one must be cut in order to expose the nerves. Remove enough 
 of the serratus magnus to expose the first rib. Cut the rib a little ventral 
 to the A. Axillaris, also cut it close to the tuberosity of the rib and remove 
 the detached portion. The A. cervicalis inferior should now be traced to 
 its place of origin from the A. Axillaris. With a little care the ventral 
 divisions of the first two thoracic nerves may be found and cut close to 
 the intervertebral foramina ; the 7th and- 8th cervical nerves also should 
 be cut close to the vertebrae and the arm removed. 
 
 Nn. pectorales. Before attempting to demonstrate the nerves to the 
 pectoral muscles first carefidly remove the connective tissue and fat from 
 the nerves of the brachial plexus using for this purpose the forceps, the back 
 of the scalpel, or some other non cutting instrument. The origin of the 
 pectoral nerves vary somewhat in different individuals. The following 
 disposition however, is common. The most cephalic or anterior of the 
 pectoral nerves originates from the 7th and 8th cervicals and is distributed 
 wholly to the anterior deep pectoral muscle (PL I, 27). The nerve enters 
 the muscle a little dorsal to the cephalic vein where it crosses the anterior 
 deep pectoral. A communicating branch between this nerve and the 
 phrenic is quite commonly present. The nerves to the superficial pectoral 
 muscles arise from the loop or arch formed by the N. musculo-cutaneous 
 (PL I, 29) and the N. medianus (PL I, 32) immediately beneath the A. axil- 
 
8 " 
 
 laris and from the brachial plexus, in common with the N. medianus (PI. I, 
 30, 31). Carefully dissect up the overlying posterior portion or sternal 
 extremity of the anterior deep pectoral and trace the nerves to their respec- 
 tive places of distribution in the superficial pectoral muscles. The two or 
 more nerves to the posterior deep pectoral and the panniculus are readily 
 found. They arise from the brachial plexus apparently in common with 
 the Nn. medianus and ulnaris. The smaller and more anterior of the 
 two nerves (in the present specimen) soon divides into three or four 
 branches which enter the muscle near its humeral end along with the 
 artery and vein supplied to the muscle. The larger and more posterior 
 nerve also divides into several branches some of which are distributed to 
 the posterior deep pectoral and some to the panniculus ; note particularly 
 the large branch which accompanies the large V. thoracica externa which 
 runs along the dorsal margin of the posterior deep pectoral and is continued 
 posteriorly in the panniculus. 
 
 A. suprascapularis arises from the A. axillaris near the anterior border of 
 the tendon of the subscapularis, and close to the N. musculo-ctitaneous 
 where it crosses the A. axillaris. About one centimeter from its origin 
 the A. suprascapularis divides into two branches, of which one is distributed 
 to the subscapularis, anterior deep pectoral and the supraspinatus ; the 
 other branch is distributed to the anterior deep pectoral, supraspinatus, 
 the shoulder joint, and the proximal tendon of the biceps. The artery is 
 accompanied by the V. suprascapularis. 
 
 N. suprascapularis (PI. I, 28; PL II, 21) originates from the 7th and 8th 
 cervical nerves but principally from the 7th; occasionally some fibres 
 originate from the 6th cervical nerve also. This large nerve passes between 
 the adjacent borders of the supraspinatus and subscapularis. Carefully 
 dissect the supraspinatus from the adjoining subscapularis, on one side 
 of it, and the infraspinatus, on the other, and transect the muscle opposite 
 the N. suprascapularis. Reflect the muscle sufficiently to expose the 
 two or three large branches of the nerve to the supraspinatus, which branches 
 are given off just as the nerve crosses the anterior border of the scapula. 
 Trace the nerve across the supraspinus fossa and note its width, i to 2 cm. 
 opposite the spine of the scapula. Just as the nerve enters the M. infra- 
 spinatus it divides into 5 or 6 branches, all of which are distributed to this 
 muscle. 
 
 Nn. subscapulares (PI. I, 47). There are usually two or more of these 
 nerves. They pass directly to the M. subscapularis but before reaching 
 it they divide into numerous branches which diverge somewhat like the 
 rays of a fan. 
 
The nerve to the M. latissimus arises from near the middle of the brachial 
 plexus, most of its fibres coming from the 8th cervical (PI. I, 48). It 
 passes obliquely across the deep face of the Mm. subscapularis and teres 
 major and is distributed wholly to the latissimus. 
 
 Nerves to the M. teres major {PI. I, 7). There are from i to 3 small nerves 
 supplied to this muscle. They arise from the N. axillaris or rather are 
 branches of it, and pass directly to the muscle, close to its anterior border. 
 
 N. axillaris (PL I, 46) arises from the 7th and 8th cervical nerves. It 
 passes through the triangular space formed by the Mm. subscapularis, 
 teres major, and the caput longum tricipitis. To demonstrate the distri- 
 bution of the nerve first remove the skin and the panniculus from the 
 lateral or external surface of the scapidar region. Dissect up the borders 
 of the M. deltoideus and transect it about 15 to 18 cm. from its attachment 
 to the deltoid tuberosity. Carefully reflect the humeral portion of the 
 muscle in order to expose the N. axillaris which enters the deep face of the 
 muscle directly opposite the above mentioned triangular space (PI. II, 22). 
 Beneath the muscle, the nerve divides into several branches which are 
 distributed as follows: several branches enter the deltoideus; one large 
 branch passes obliquely across the superficial surface of the teres minor 
 (near its humeral end) to the anterior face of the brachium and enters the 
 mastoido-humeralis several centimeters below (distal to) the point of the 
 shoulder (PL I, 24); another large branch crosses the superficial surface 
 of the caput laterale tricipitis or sometimes, is embedded in the substance 
 of this muscle, and emerges from beneath the posterior border of the M. 
 deltoideus at the level of the deltoid tuberosity where it becomes subcutane- 
 ous (PL II, 23) ; from here, this subcutaneous branch extends to the antero- 
 intemal aspect of the antebrachiiim where it breaks up into several cutaneous 
 branches some of which extend nearly to the carpus. One branch of the 
 N. axillaris is distributed to the teres minor. This branch may be readily 
 demonstrated by transecting the muscle, a little proximal to the N. axillaris, 
 and drawing aside the muscle. One or more branches are supplied to 
 the teres major, one branch to the subscapularis and a very small filament 
 to the M. capsularis. The branches to the subscapularis and the capsularis 
 may arise from the main nerve trunk either separately or by a common 
 branch. 
 
 Clean up the V. axillaris and the several veins from the pectoral, pannicu- 
 lus, and latissimus muscles also clean up the portion of the V. subscapularis 
 that lies in the space between the Mm. subscapularis and teres major. 
 Demonstrate the axillary lymph gland (PL I, 49), which lies on the tendon 
 
10 
 
 of the teres major in the angle formed by the Vv. subscapularis and 
 brachialis. Now slit the posterior superficial pectoral longitudinally near 
 its middle. Turn aside the anterior portion of the muscle, together with 
 the posterior deep pectoral, in order to expose the Mm. coraco-brachialis 
 and the biceps brachii. 
 
 N. musculo-cutaneous (PL I, 29, 29') is a large nerve and originates from the 
 7th and 8th cervical nerves. Immediately after crossing the lateral face of 
 the A. axillaris (PL I, 21) a large portion of the nerve joins the N. medianus 
 by a large short branch that passes beneath the A. axillaris and with the 
 N. medianus forms a loop around it. Occasionally this nerve loop is 
 entirely wanting. From the loop thus formed, one or more branches are 
 given ofi to the superficial pectoral muscles as already demonstrated. The 
 larger portion of the N. musculo-cutaneous however, passes through the M. 
 coraco-brachialis (PL I, 13, 29'), the overlying portion of which should be cut 
 just proximal to the nerve, and drawn aside. As the nerve enters the 
 coraco-brachialis it supplies a branch to it. Trace the main nerve through 
 the coraco-brachialis to its termination in the biceps brachii near to the 
 proximal end of the fleshy portion of the muscle (PL I, 29'). The connective 
 tissue and aponeurosis covering the vessels and nerves on the medial face 
 of the brachial region should now be removed. Note that here the vessels 
 and nerves have the following relations, viz., the N. medianus lies most 
 anteriorly and is followed in order by the A. brachialis, V. brachialis, N. 
 ulnaris, and finally, in the proximal part of the brachium, the large N. 
 radialis. Note also the small mass of lymph glands lying on the artery 
 and vein near the distal third of the brachium (PL I, 49'). 
 
 N. radialis (PL I, 40) lies posterior to the Nn. medianus and ulnaris and is 
 the largest nerve of the brachial plexus. It originates from the 7th and 8th 
 cervical and the ist thoracic nerves, but principally from the 8th cervical 
 and I St thoracic. The nerve passes into the triangular space formed by 
 the tendon of the teres major and latissimus, the caput longum tricipitis 
 and the proximal end of the brachiahs. An artery and vein also enter this 
 space and should be left intact. As the N. radialis enters the above men- 
 tioned triangular space it gives off several branches which are distributed 
 as follows: (a) one branch to the tensor fasciae antebrachii (PL I, 44). 
 To demonstrate this branch, transect the tensor fasciae antebrachii near 
 its distal third and turn the muscle aside but do not injure the nerve (a 
 branch of the N. ulnaris) which runs along the anterior border (PL I, a), 
 or sometimes crosses obliquely, the superficial surface of the distal 
 half of the muscle. Sometimes a small communicating branch passes from 
 
II 
 
 the N. ulnaris to this branch of the N. radiahs supphcd to the tensor fasciae 
 antebrachii. (b) A large fasciculus composed of several branches, some 
 of which recurve slightly around the tendon of the teres major and latis- 
 simus; all the branches of this fasciculus are distributed to the caput 
 longum tricipitis (PI. I, 41). (c) Branches to the caput laterale tricipitis, 
 caput mediale tricipitis, and anconeus. Of these branches the small one 
 to the caput mediale is readily found and traced to its muscle; the branches 
 to the caput laterale and anconeus, however, are more or less completely 
 hidden by the caput longum and caput laterale and often can be satis- 
 factorily demonstrated only after the caput laterale has been dissected 
 as follows: Turn aside the skin and the panniculus from the outer surface 
 of the triceps. The posterior surface of the caput laterale may now be 
 freely separated from the caput longum, but in dissecting up the anterior 
 border of the muscle care should be taken not to cut the cutaneous nerve 
 (a branch of the N. radialis) which emerges from beneath the muscle at, 
 or close to, its anterior border (6 to 8 cm. distal to the cutaneous branch 
 of the N. axillaris, or 8 to 10 cm. from the posterior edge of the M. deltoideus, 
 PL II, c). Transect the caput laterale a little distal to its middle and 
 freely reflect the distal portion of the muscle; the proximal portion of the 
 muscle can be turned aside only a little distance as the nerve and blood- 
 vessels to the muscle enter its deep or anterior face. Trace this nerve and 
 also the cutaneous branch to their origin from the N.. radialis. Now trace 
 the main trunk of the N. radialis in its course along the musculo-spiral groove 
 to the point where it passes beneath the M. extensor carpi radialis at its 
 origin, near the proximal end of the external epicondyle of the humerus 
 (PL II, 1 1 , 25) . Remove the skin of the antebrachivim as far as to the carpus. 
 Trace the cutaneous branches of the N. axillaris and the N. radalis, the 
 former to the antero-internal side of the antebrachium and the latter to 
 the antero-extemal side of the antebrachium. Both of these cutaneous 
 branches may readily be traced to near the carpus. The M. extensor carpi 
 radialis should now be dissected as follows: Transect it near the middle 
 and freely turn aside the distal portion, but in turning aside the proximal 
 part of the muscle care must be exercised to avoid cutting or breaking 
 the nerves and blood-vessels that enter the deep face of the muscle (near 
 the posterior border of the distal end of the M. brachialis). Now trace the 
 N. radialis beneath the proximal portion of the extensor carpi radialis 
 taking care not to cut the branches of this nerve, usually three in number, 
 that enter the deep face of the muscle (PL II, d). The main nerve now 
 passes beneath the extensor digitalis communis, near the origin of the 
 muscle. Transect the extensor digitalis communis near the middle of the 
 antebrachium and as the proximal portion is reflected avoid breaking the 
 
12 
 
 blood-vessels and the two or three branches of the N. radialis supplied to 
 the muscle (PI. II, e). Beneath this muscle the N. radialis gives off a small 
 branch to the extensor carpi obliquus (PI. II, f) ; this branch lies directly upon 
 the anterior-lateral face of the radius, at the side of the A. radialis anterior, 
 and beneath the deep face of the extensor digitalis communis which must 
 be turned aside sufficiently to expose the extensor carpi obliquus. Shortly 
 before the N. radialis passes beneath the extensor digitalis lateralis, close 
 to its origin, it gives off a small branch to this muscle (PL II, g). 
 Slit open the aponeurotic sheath of the muscle and trace the branch some 
 little distance. Now transect the muscle at the level of the N. radialis 
 and trace the latter into the flexor carpi extemus where the nerve terminates 
 (PL II, h). It will be seen from the above that the N. radialis supplies 
 the following muscles; the triceps (caput longum, laterale and mediale), 
 the tensor fasciae antebrachii, the anconeus, the extensor carpi radialis, 
 the extensor digitalis communis, the extensor digitalis lateralis, the extensor 
 carpi obliquus, and the flexor carpi externus, and one or more cutaneous 
 branches to the skin of the antebrachium. 
 
 Blood-vessels of the Brachial Region 
 
 The large V. axillaris and several of the vessels opening into it, viz., 
 V. thoracico-dorsalis from the deep pectoral muscles; the V. suprascapu- 
 laris, the V. thoracico-externa together with the branches from the latissi- 
 mus and panniculus that communicate with the V. thoracico-externa a 
 short distance from its termination, have already been exposed. Additional 
 veins should be noted as they are uncovered in the further dissection. 
 
 A. axillaris (PL I, 21). Upon emerging from the thorax the A. axillaris 
 
 crosses the tendon of origin of the coraco-brachialis and the insertion of 
 the subscapularis, at the postero-internal side of the scapulo-humeral 
 joint. From here the artey is continued by the A. brachialis (PL I, 23) 
 which extends obliquely across the middle of the humerus to the antero- 
 intemal side of the distal third of the shaft of the bone where it divides 
 into two terminal branches — the A. radialis anterior and the A. radialis 
 posterior. 
 
 Branches of the A. axillaris, 
 
 A. cervicalis inferior. 
 A. suprascapularis. 
 A. subscapularis. 
 The A. cervicalis inferior and the suprascapularis have already been 
 traced, pp. 5, 8. The large A. subscapularis (PL I, 22) arises from the 
 
13 
 
 axillaris at the posterior border of the M. subscapularis. Before exposing 
 the A. subscapularis first trace the branch, A. thoracico-dorsalis, that arises 
 from the subscapularis i to 2 cm. from its origin (PI. I, immediately below 
 22). This artery extends obliquely across the inner face of the teres major 
 supplies small branches to it and to the axillary lymph gland and terminates 
 in the latissimus and panniculus. Transect the M. teres major near the 
 middle and turn it aside. Now trace the A. subscapularis between the 
 Mm. subscapularis and teres major across the inner surface of the caput 
 longtim tricepitis to the posterior angle of the scapula. The A. subscap- 
 ularis gives ofif the following branches: » 
 
 (i) A. thoracico-dorsalis already dissected. See above. 
 
 (2) A. circumflexa humeri posterior arises i to 2 cm. peripheral to 
 the A. thoracico-dorsalis. It accompanies the N. axillaris to the deep face 
 of the M. deltoideus and is distributed to this muscle and also to the caput 
 longum, the caput laterale, the brachialis, the teres minor and a small twig 
 to the capsule of the scapulo-humeral joint. 
 
 (3) A. circumflexa scapulae arises from the subscapularis 5 to 8 cm. 
 peripheral to the A. circumflexa humeri posterior and extends directly to 
 the posterior border of the scapula; here it divides into two branches of 
 which one passes to the outer and the other to the inner surface of the 
 scapula. The outer branch crosses, at nearly a right angle, the outer face 
 of the scapula, a little below the spine, and is distributed to the infra and 
 supraspinati and the teres minor. The inner branch is distributed to the 
 subscapularis. The general course of these vessels is indicated by the 
 vasciilar grooves of the scapula. (See cleaned scapula.) 
 
 (4) Rami musculares. Numerous small branches of the A. sub- 
 scapularis are supplied to the IVIm. subscapularis and teres major. Two 
 or more large branches of the A. subscapularis are given off to the caput 
 longum, the tensor fasciae antebrachii, the infraspinatus and the deltoideus. 
 The V. subscapularis accompanies the artery. 
 
 A. circumflexa humeri anterior arises from the brachialis i to 4 cm. periph- 
 eral to the subscapularis. It passes between the hixmerus and the M. 
 coraco-brachialis, supplies a branch to this muscle and terminates in the 
 biceps brachii and mastoido-hiuneralis. (The biceps may now be tran- 
 sected.) It gives off a branch which extends towards the scapiilo-humeral 
 joint and is distributed to the biceps brachii and its s^^novial tendon sheath. 
 Occasionally the A. circumflexa humeri anterior is a small vessel supplying 
 only the coraco-brachialis. 
 
14 
 
 A. profunda brachii (PI. I, 24) is a large but very short trunk, i to 3 cm. 
 in length, which arises from the brachialis near the middle of the brachium, 
 or at the level of the lower border of the tendon of the teres major and latis- 
 simus. The artery divides into several branches which are distributed 
 to the caput longtmi, caput laterale and the brachialis. Not infrequently 
 this artery is double at its origin. 
 
 A muscular branch to the biceps brachii originates from the anterior side 
 of the brachialis, 6 to 8 cm. distal to the A. profunda brachii and nearly 
 opposite the A. ulnaris, and enters the biceps a little below the middle 
 of the muscle (PI. I). Occasionally it gives off a branch of considerable 
 size to the M. brachialis. Turn aside the distal portion of the tensor fasciae 
 antebrachii taking care not to ctit the cutaneous nerve (a branch of the 
 ulnaris) which lies at the anterior border of this portion of the muscle. 
 
 A. ulnaris (PI. I, 25) arises from the brachialis near the nutrient foramen, 
 at the distal third of the shaft of the humerus. The artery passes beneath 
 the tensor fasciae antebrachii and along the anterior border of the caput 
 mediale to the posterior part of the humero-radial joint where it passes 
 beneath the antebrachial aponeurosis and the small ulnar head of the 
 M. flexor carpi medius. Its further course along the antebrachium should 
 be deferred until later. 
 
 Branches of A. ulnaris. Close to its origin it gives off a long small 
 branch that winds obliquely across the internal and anterior faces of the 
 tendon of the biceps brachii and extends to the posterior superficial pectoral 
 and to the antebrachial aponeurosis. (Sometimes this small branch arises 
 from the A. brachialis) (PI. I, just below 34')- About i to 2 cm. peri- 
 pheral to the above branch the A. ulnaris gives off a larger, long, branch 
 to the middle and posterior portions of the posterior superficial pectoral. 
 The A. ulnerus also gives off one or more small branches to the tensor 
 fasciae antebrachii and a branch of considerable size enters the olecranon 
 fossa and supplies the joint capsule. The V. ulnaris accompanies the 
 artery. 
 
 A. nutritia humerii (nutrient artery of the hiunerus). 
 
 The nutrient artery of the humerus sometimes arises directly from the 
 brachialis and sometimes from the ulnaris. It passes directly into the 
 nutrient foramen of the humerus. 
 
 Remove the skin from the inner side of the antebrachium, if it has not 
 already been removed, and slit longitudinally the antebrachial aponeurosis. 
 Identify the small, thin, ulnar head of the flexor carpi medius (PI. I, 17'); 
 
15 
 
 turn this aside taking care not to cut the very smah filament supphcd to it 
 from the N. ulnaris which Has immediately under the ulnar head of this 
 muscle (PL I, e). Now trace the A. ulnaris (vein and nerve also) along 
 the antebrachium noting that in the proximal half of this region the artery 
 lies between the ulnar and humeral heads of the flexor perforans and in 
 the distal half of the antebrachium it lies between the flexor carpi medius 
 and the flexor carpi extemus. Note that the nerve, artery and vein lie 
 side by side and are immediately beneath the aponeurosis. Transect the 
 flexor carpi medius near its middle and reflect the distal portion in order 
 to expose the supracarpal arch which is formed by the anastomosis of 
 the A. ulnaris with a branch from the A. metacarpae volaris lateralis, a 
 little proximal to the carpus (PL III, i6). In demonstrating this vascular 
 arch be careful not to cut any of the vessels arising from it. Two to four 
 centimeters below the origin of the A. ulnaris the A. brachialis divides into 
 its' two terminal branches — the A. radialis anterior and the A. radialis 
 posterior. 
 
 N. ulnaris (PL I, 39) arises from the ist and 2d thoracic nerves. It lies 
 posterior to the brachial artery and vein and between the median and 
 radial nerves, the median being anterior and the radial posterior to it. 
 Near the middle of the brachium the nerve passes beneath the tensor 
 fasciae antebrachii and extends to the humero-radial joint where, with the 
 A. and V. ulnaris, it dips beneath the small ulnar head of the flexor carpi 
 medius (PL I, 17')- Near the middle of the brachium, a little before pass- 
 ing beneath the tensor fasciae antebrachii, the nerve gives off a cutaneous 
 branch which extends along the anterior border of the tensor fasciae ante- 
 brachii and between it and the posterior superficial pectoral (PL I, a). 
 The nerve does not supply the posterior superficial pectoral but passes 
 through it and extends subcutaneously along the posterior face of the ante- 
 brachium nearly to the carpus. At the humero-radial joint the N. ulnaris 
 gives off several branches the smallest of which supplies the ulnar head of 
 the flexor carpi medius (PL I, e); a larger branch goes to the ulnar head 
 of the flexor perforans (PL I, d) and the two largest branches are distributed 
 one to the humeral head of the flexor carpi medius, and the other to the flexor 
 perforatus. Occasionally the humeral head of the flexor perforans receives a 
 branch from the N .ulnaris. These branches are all easily demonstrated and need 
 no special directions for their dissection other than to turn aside the proximal 
 portion of the flexor carpi medius in order to see the place where the branch 
 that supplies it enters its deep face near the proximal end of the muscle. 
 Now trace the N. ulnaris along its antebrachial course, noting carefully 
 its relation to the aponeurosis, to the flexor perforans to the middle and 
 
i6 
 
 external flexors of the carpus and to the artery and vein. Five to eight 
 centimeters from the carpus the nerve divides into two branches of which 
 one pierces the aponeurosis and passes, subcutaneously, across the tendon 
 of the flexor carpi externus and divides into numerous branches which extend 
 obliquely to the antero-lateral face of the carpus and metacarpus (PI. Ill, 
 25'; PI. II, 26). The other terminal branch of the N, ulnaris unites with a 
 branch of the N. medianus, below the supracarpal arch, and thus forms the 
 N. volaris lateralis (PI. Ill, 26). 
 
 A. radialis anterior (PI. II, 19) is the smaller of the two terminal branches 
 of the A. brachialis. It passes obliquely downward and outward between 
 the anterior face of the humerus and the Mm. biceps brachii and the 
 brachialis. Transect the brachialis where it crosses the external surface of 
 the tendon of the biceps. Beneath the brachialis and the extensor carpi 
 radialis, the artery supplies branches to these muscles. Beneath the exten- 
 sor digitalis communis the A. radialis anterior gives off two or three small 
 branches to this muscle; it also sends a branch to the extensor digitalis 
 lateralis and to the flexor carpi externus. The A. radialis anterior is 
 continued as a small branch which extends along the antero-intemal 
 aspect of the radius to the carpus where it joins the rete carpi dorsalis. 
 
 A. radialis posterior (PL I, 26) is the direct continuation of the A. brachialis 
 
 and is the larger of its two terminal branches. The artery crosses the 
 antero-intemal face of the humero-radial joint and is here covered by 
 the skin, the aponeurosis and the posterior superficial pectoral muscle. 
 Note that in this region the N. medianus, as it passes from the posterior 
 to the anterior side of the artery and vein, lies superficially to the blood- 
 vessels (PL I). A little below the humero-radial joint the A. radialis 
 posterior, accompanied by the N. medianus, passes under the flexor carpi 
 internus (PL I, 16) which should be transected and turned aside. Beneath 
 this muscle it extends to the distal third of the shaft of the radius and is then 
 continued by the large A. digitalis communis and the two metacarpal 
 arteries. 
 
 Branches of the A. radialis posterior. 
 
 (i) One or more small branches to the humero-radial joint. 
 
 (2) Muscular branches to the flexor carpi internus and medius and 
 to the flexor perfortus and perforans. 
 
 (3) A. interossea communis, is a large branch that arises from the 
 radialis posterior near the level of the radio-ulnar arch through which the 
 interossea communis passes. In the interosseous space it gives off the 
 nutrient artery of the radius. After passing through the interosseus space 
 
17 
 
 the artery gives ofif one or more branches to the flexor carpi extemus, 
 anastemoses with the radiahs anterior, and is continued along the antero- 
 extemal face of the radius, beneath the common digital extensor, to the 
 carpus where it anastemoses by a fine branch with the radialis anterior 
 and also commonly joins the rete carpi dorsalis. Near the proximal third 
 of the radius it gives off a small branch which runs along the extensor digi- 
 talis lateralis, supplies twigs to this muscle and to the extensor carpi obliquus. 
 One or two centimeters distal to the interossea communis the A. radialis 
 posterior may give off another branch nearly as large as the A. interossea 
 communis. This second branch (in the present specimen) crosses at a 
 right angle the posterior face of the radius then turns towards the carpus 
 and is distributed by numerous branches to the flexor perforans and flexor 
 perforatus. 
 
 N. medianus (PI. I, 32) arises from the 8th cervical and ist thoracic nerves. 
 Immediately below the A. axillaris the nerve usually receives a large branch 
 from the N. musculo-cutaneous thus forming with it a loop through which 
 the artery passes (PL I) . Near the middle of the brachium the N. medianus 
 gives off a large branch which extends very obliquely beneath the biceps, 
 rarely sending a small filament to it, and divides into two branches (PL I, 
 34, 35) of which one is distributed to the brachialis; the other branch 
 winds very obliquely across the lateral face of the biceps, near the distal 
 end, to the antero-internal face of the antebrachium where it divides into 
 two principal branches which accompany the two respective subcutaneous 
 veins, i.e. the cephalic and accessory veins, on the inner surface of the 
 antebrachium (PL I, 34') • The vein should of course, be dissected along with 
 the nerves. The larger of the two subcutaneous branches of the nerve may 
 be traced to the middle of the metacarpus. The main trunk of the N. 
 medianus and the artery and vein radialis posterior, after crossing the 
 humero-radial joint, pass beneath the flexor carpi internus as already 
 demonstrated (PL I, 16). Note very carefully the relation of the nerve, 
 artery and vein to each other and to the posterior superficial pectoral 
 muscle and to the internal tuberosity of the radius. Median neurectomy 
 is performed in this region and also the pulse may here be readily felt. 
 A little before the N. medianus passes beneath the flexor carpi internus it 
 gives off two or three branches which are distributed as follows: One or 
 two branches, to the flexor carpi internus (PL I, 36); a much larger branch 
 which soon divides into two parts both of which are distributed to the 
 humeral portion of the flexor perforans (PL I, 37) ; and finally a small nerve 
 which also divides into two branches (PL I, 38) one of which extends into 
 the radio-ulnar arch and is distributed principally to the periosteum; the 
 
other branch extends along the posterior face of the radius to the radial 
 head of the flexor perforans to Which it is distributed. Continue the dis- 
 section of the N. medianus in its course beneath the flexor carpi internus. 
 Near the distal third of the antebrachium the nerve (PL III, 24) divides 
 into two terminal branches one of which unites with a branch of the N. 
 ulnaris as already seen, and with it forms the N. volaris lateralis (PI. Ill, 
 26); the other terminal branch of the N. medianus forms the N. volaris 
 medialis (PI. Ill, 27). 
 
 N. volaris lateralis, as already stated, is formed by the union of two branches, 
 one from the N. ulnaris and the other from the N. medianus. The N. 
 volaris lateralis, accompanied by a small artery (A. metacarpea volaris 
 lateralis) and vein, crosses the carpus at the medial side of the pisiform 
 bone, in a special channel in the carpal sheath. At the proximal end of 
 the metacarpus the nerve gives off a large branch to the suspensory ligament ; 
 before tracing this branch however, follow the N. volaris lateralis as far 
 as to the fetlock noting the branch of considerable size from the N. volaris 
 medialis that joins it a little proximal to the distal end of the rudimentary 
 metacarpal (PL III, 28). Transect the two flexor tendons near the middle 
 of the metacarpus taking care not to injure the N. volaris medialis and the 
 large artery and vein at the medial side of the tendons (PL III). Reflect 
 the proximal portion of the tendons and carefully trace the branch from 
 the N. volaris lateralis to the suspensory ligament to which it supplies 
 more small branches and also two branches that accompany the respective 
 two or arteries metacarpea volaris medialis and lateralis. 
 
 A. retis carpi volaris is a small vessel which arises from the A. radialis 
 posterior near the distal third of the antebrachiiim and descends to the 
 posterior surface of the carpus where it divides into several small branches 
 which help to form the rate carpi volare. 
 
 A. metacarpea volaris lateralis. This is the smallest of the three branches 
 that continue the A. radialis posterior. It arises from the lateral side of 
 the A. radialis posterior, crosses the medial face of the pisiform bone, with 
 the N. volaris lateralis, and continues to the proximal end of the meta- 
 carpus. Here it is connected with the A. metacarpea volaris medialis 
 usually by two transverse branches, thus forming the arcus volaris pro- 
 fundus. The larger of the two transverse branches lies between the sub- 
 carpal or inferior check ligament of the perforans tendon and the suspensory 
 ligament: the other transverse branch, not always present, lies between 
 the suspensory ligament and the large metacarpal bone. Cut the suspen- 
 sory ligament near the middle and draw it aside. Below the deep vascular 
 
19 
 
 arch, the A. metacarpa volaris lateralis runs in a flexuous course on the 
 posterior face of the large metacarpal bone, close to the lateral rudi- 
 mentary metacarjDal. Near the distal third of the metacarpus the artery- 
 unites with the A. metacarpea volaris medialis to form a short trunk which 
 joins the A. digitalis lateralis close to the origin of the latter. 
 
 A. metacarpea volaris medialis (PI. Ill, 17) arises from the radialis posterior, 
 
 usually a little proximal to the metacarpea volaris lateralis, and is con- 
 siderably larger than that artery. It passes across the postero-internal 
 face of the carpus with the large vein of the same name, imbedded in the 
 carpal sheath or posterior annular ligament. At the proximal end of the 
 internal rudimentary metacarpal it is connected with the A. metacarpea 
 volaris lateralis, usually, by two transverse branches (arcus volaris pro- 
 fundus) as mentioned above. It then continues in a flexuous course, on 
 the posterior internal face of the large metacarpal, to near the distal third 
 of the metacarpus where it unites with the metacarpea volaris lateralis 
 to form a short common trunk which joins the A. digitalis lateralis. The 
 nutrient artery of the large metacarpal bone is a branch of the metacarpea 
 volaris medialis. 
 
 A. metacarpea dorsalis lateralis and A. metacarpea dorsalis medialis are 
 
 two very small arteries that have a variable origin. Sometimes they arise 
 from the A. metacarpea volaris, of the same side, at the level of the deep 
 vascular arch. They extend anteriorly across the heads of the rudimentary 
 metacarpals, descend in the grooves between the large and small metacarpal 
 bones, and anastamose with the corresponding A. metacarpea volaris. 
 Sometimes these two small arteries arise from the rete carpi dorsalis and 
 in other cases, they arise in part from the rete carpi dorsalis and in part 
 from the A. metacarpea volaris lateralis and the A. metacarpea volaris 
 medialis. 
 
 A. digitalis communis (PL III, 18) is the largest and most direct, continua- 
 tion of the A. radialis posterior. It extends through the carpal canal at 
 the medial side of the flexor tendons, in company with the N. volaris 
 medialis. Slit open the carpal canal and trace the artery and the large 
 metacarpal vein that, in the metacarpal region, accompanies the artery 
 along the medial side of the flexor tendons to near the fetlock where the 
 artery divides into the A. digitalis lateralis and the A. digitalis medialis. 
 Remove the hoof or horn capsule. 
 
 N. volaris medialis (PL III, 27) is formed by one of the terminal branches of 
 the N. medianus. It passes through the carpal canal in close company with 
 
20 
 
 the large A. digitalis communis and both artery and nerve are in close 
 relation with the flexor tendons. Note that near the middle of the meta- 
 carpus the nerve gives off a large branch which crosses very obliquely the 
 posterior face of the flexor tendons and joins the N. volaris lateralis a little 
 above the distal extremity of the nidimentary metacarpal (PI. Ill, 28). 
 At the level of the sesamoid bones of the fetlock, the nerve divides into 
 two, sometimes three, branches, viz., an anterior, a middle, if present, and a 
 posterior branch (PI. Ill, 30, 31, t,2). These branches are of very unequal 
 size, the posterior being much the largest and the most important. This 
 branch is the one that is cut in the operation of low neurectomy. The anter- 
 ior branch descends in front of the vein and is distributed to the skin on the 
 anterior face of the digit and to the coronary band or matrix. The middle 
 branch is small and irregular; it descends between the artery and vein and 
 is generally formed by the union of several small branches which cross over 
 the artery before uniting. This branch terminates in the coronary band 
 or matrix and the sensitive laminae. The posterior branch lies close behind 
 the artery, except at the fetlock, where the nerve is more superficial than the 
 artery. This posterior branch accompanies the digital artery and will be 
 traced with it. It is distributed to the sensitive laminae, sole and frog. 
 
 A. digitalis lateralis and A. digitalis medialis are formed by the bifur- 
 cation of the digitalis communis near the distal third of the metacarpus. 
 Each artery passes over the outer surface of the corresponding sesamoid 
 bone at the fetlock, and descends parallel to the borders of the deep flexor 
 tendon to the volar foramina of the third phalanx; in the semilunar canal 
 of this bone the two arteries anastomose with each other. Expose the 
 artery of one side, as follows: remove the lateral cartilage and the anterior 
 or apical two-thirds of the plantar cushion; remove also, the portion of 
 the deep flexor tendon that is exposed by the removal of the anterior part 
 of the plantar cushion, i.e. the portion of tendon in relation to the navicular 
 bone and the semilunar crest of the third phalanx. Each digital artery is 
 accompanied by a vein and the two or three branches of the volar nerves. 
 Proximal to the fetlock the artery lies deeply and is covered by the vein 
 and nerve; at the fetlock the three structures lie at the same level, the vein 
 being anterior and the large posterior branch of the nerve back of the artery. 
 The anterior branch of the volar nerve crosses obliquely the digital 
 artery and vein at, or a little below, the fetlock (PI. Ill, 30). The vessels 
 and nerves are crossed obliquely by a small ligamentous band extending 
 from the ergot to the fascia at the side of the first interphalangal or pastern 
 joint (PI. Ill, 13). 
 
21 
 
 Branches of the A. digitalis lateralis. 
 
 (i) Numerous small branches to the ergot, joints, tendons and tendon 
 sheaths. 
 
 (2) A. phalangis primae. (Artery of the first phalanx). This is a 
 short trunk whicli arises at a right angle near the middle of the first phalanx 
 and divides almost immediately into an anterior and a smaller posterior 
 branch. The anterior branch divides into an ascending and a descending 
 portion both of which are distributed on the anterior face of the first phalanx. 
 A branch passes between the extensor tendon, which should be cut, and the 
 first phalanx and anastamoses with the corresponding artery of the oppo- 
 site side. The small posterior branch of the A. phalangis primae divides 
 into several branches of which one passes between the infrasesamoidean 
 ligaments and the first phalanx and anastomoses with the opposite artery; 
 the other branches are distributed to the structures on the posterior face 
 of the first phalanx. 
 
 (3) A. toricae phalangis tertia (artery of the plantar cushion) arises 
 at a right angle from the digitalis, at the proximal border of the lateral 
 cartilage. It extends postero-distally and is distributed to the plantar 
 cushion and to the matrix of the frog. 
 
 (4) A. dorsalis phalangis secundae (dorsal or anterior artery of the 
 second phalanx). This artery arises at a right angle from the digitalis, 
 near the middle of the second phalanx, and under cover of the lateral 
 cartilage. It extends anteriorily beneath the lateral cartilage and the 
 extensor tendon and anastomes with its fellow of the opposite side. Just 
 as it passes beneath the extensor tendon it gives off a branch to the coronary 
 band or matrix ; it also supplies small branches to the tendon and to the 
 joint capsule. A branch of the volar nerve accompanies the artery. 
 
 (5) A. volaris phalangis secundae (ventral or posterior artery of the 
 second phalanx) is smaller than the preceding opposite to which it arises. 
 It passes above the proximal border of the navicular bone and anastomoses 
 with its fellow of the opposite side. 
 
 (6) A. dorsalis phalangis tertiae (dorsal artery of the third phalanx) arises 
 from the digitalis at the inner or medial side of the wing of the third phalanx. 
 In company with the posterior branch of the N. volaris, it passes through 
 the notch (or foramen) of the wing of this bone and extends anteriorly in 
 the vascular groove on the lateral surface of the bone. It gives off a pos- 
 terior branch to the plantar cushion. 
 
 The branches of the A. digitalis medialis are the same as those of the 
 A. digitalis laterales. 
 
PLATE I 
 MEDIAL OR INNER VIEW OF THE PECTORAL LIMB 
 
 1. i' Posterior superficial pectoral. 
 
 2. Anterior superficial pectoral. 
 
 3. Posterior deep pectoral. 
 
 4. Anterior deep pectoral. 
 
 5. M. supraspinatus. 
 
 6. M. subscapularis. 
 
 7. M. teres major. 
 
 8. M. latissimus dorsi. 
 
 9. M. panniculus. 
 
 g'. Aponeurotic tendon of panniculus. 
 
 10. to'. Tensor fasciae antebrachii. 
 
 11. M. caput longum tricipitis. 
 
 12. M. caput mediale tricipitis. 
 
 13. M. coraco-brachialis. 
 
 14. M. biceps brachii. 
 
 15. Aponeurotic tendon-slip from biceps brachii. 
 
 16. M. flexor carpi internus. 
 
 17. M. flexor carpi medius. 
 
 17'. Ulnar head of flexor carpi medius. 
 
 18. Ulnar head of flexor perforans. 
 
 19. M. flexor perforatus. 
 
 20. M. flexor perforans. 
 
 21. A. axillaris. 
 
 22. A. subscapularis. 
 
 23. A. brachiaHs. 
 
 24. A. profunda brachii. 
 
 25. 25'. A. ulnaris. 
 
 26. A. radialis posterior. 
 
 VII, VIII, I, II, = 7th - 8th cervical and 1st and 2d thoracic nerves. 
 
 27. Nerve to anterior deep pectoral. 
 
 28. N. suprascapularis. 
 
 29. 29'. N. musculo-cutaneous. 
 
 30. 30'. Nn. to anterior and posterior superficial pectorals. 
 
 31. Nn. to posterior deep pectoral. 
 
 32. 32'. N. medianus. 
 
 33. Ner\-e filament to biceps brachii (very rarely present). 
 
 34. 34'. Cutaneous branch of N. medianus. 
 
 35. Branch of N. medianus to M. humeralis obliquus. 
 
 36. Branch to M. flexor carpi internus. 
 
 37. Branch to flexor perforans. 
 
 38. Small branch to radial head of flexor perforans and to the radio-ulnar arch. 
 
 39. 39'- N. ulnaris (a) cutaneous branch; (b) branch to M. flexor carpi medius; (c) branch to flexor 
 
 perforatus; (d) branch to ulnar head of flexor perforans; (e) branch to ulnar head of flexor per- 
 /< foratus. 
 
 40. "^; radialis. 
 
 41 
 42, 
 
 43 
 
 44 
 45 
 46 
 
 47 
 48 
 
 49 
 
 Branch to caput longum tricipitis. 
 
 Branch to caput longum, laterale, mediale and anconeus. 
 
 Portion of N. radialis that continues along the spiral groove to the extensors of the metacarpus and 
 
 phlanges. 
 
 Branch of N. radialis to the M. tensor fasciae antebrachii. 
 Nerve to the panniculus and posterior deep pectoral. 
 N. axillaris. 
 Nn. subscapulares. 
 Nerve to the M. latissimus dorsi. 
 Axillary lymph gland. 
 
 49' Lymph gland. 
 
PLATE II 
 
 LATERAL OR EXTERNAL VIEW OF THE PECTORAL LIMB 
 
 1. M. supraspinatus. 
 
 2, 3, 3'- M. deltoideus (transected and turned aside). 
 
 4. M. teres minor. 
 
 5. M. caput longum tricipitis. 
 5'. M. tensor fasciae antebrachii. 
 
 6. 6'. M. caput laterale tricipitis (transected and tlie distal portion turned back). 
 
 7. M. anconeus. 
 
 8. M. biceps brachii. 
 
 9. M. mastoido-hunieralis. 
 
 10. M. brachialias. 
 
 11. 11'. M. extensor carpi radialis (transected and the distal portion turned aside). 
 
 12. Radius. 
 
 13. 13'. M. extensor digitalis communis (extensor pedis) a portion of the muscle has been removed. 
 
 14. M. extensor carpi obliquus. 
 
 15. Ulnar head of M. flexor perforans. 
 
 16. M. flexor carpi externus. 
 
 17. M. extensor digitalis lateralis. 
 
 18. M. flexor perforans. 
 ig, 20. A. radialis anterior. 
 
 21. N. suprascapularis. 
 
 22. N. axillaris. 
 
 23. Cutaneous branch of N. axillaris. 
 
 24. Branch of N. axillaris to M. mastoido-humeralis. 
 
 25. 25'. N. radialis. 
 
 a. a'. Branch of N. radialis to caput laterale tricipitis. 
 
 b. Branch to M. anconeus. 
 
 c. Cutaneous branch of N. radialis. 
 
 d. Branches of N. radialis to M. extensor carpi radialis. 
 
 e. Branches to M. extensor digitalis communis. 
 
 f. Branch to M. extensor carpi obliquus. 
 
 g. Branch to M. extensor digitalis lateralis. 
 
 h. Termination of N. radialis in the M. flexor carpi externus. 
 
 26. Cutaneous branches of N. ulnaris. 
 
PLATE III 
 MEDIAL OR INNER VIEW 
 
 1 . Radius. 
 
 2. 2'. Principal and medial metacarpal bones. 
 
 3. Lateral cartilage. 
 
 4. M. extensor carpi radialis. 
 
 5. M. extensor carpi obliquus. 
 
 6. M. flexor carpi intemus. 
 
 7. M. flexor perforatus. 
 
 8. M. flexor carpi medius (turned aside). 
 
 9. M. interosseus medius. 
 
 10. M. lumbricalis medius. 
 
 1 1 . Portion of carpal sheath or annular ligament. 
 
 12. Suspensory or suprasesamoid ligament. 
 
 13. Ligament of ergot. 
 
 14. Cut edge of antebrachial aponeurosis (not clearly shown in figure). 
 
 15. A. radialis posterior. 
 
 16. Supracarpal arch. 
 
 17. A. metacarpea volaris medialis. 
 
 18. A. digitalis communis. 
 
 19. A. digitalis medialis. 
 
 20. A. ulnaris. 
 
 21. 22. V. radialis posterior. 
 
 23. V. ulnaris. 
 
 24. N. medianus. 
 
 24'. Branch of N. medianus to the N. ulnaris. 
 
 25. N. ulnaris. 
 
 25'. Cutaneous branch of N. ulnaris. 
 
 26. N. volaris lateralis. 
 
 27. N. volaris medialis. 
 
 28. Anastomosing branch from N. volaris medialis to the N. volaris lateralis. 
 
 29. Small branch to region of ergot. 
 
 30. 31, 32. Anterior, middle and posterior branches of the N. volaris medialis. 
 33. Coronary band of matrix. 
 
Dissection of the Blood -Vessels and Nerves of 
 the Leg or Pelvic Limb 
 
 Remove the intestines and transect the body immediately caudal to 
 the last pair of ribs. In the male, find the spermatic veins and the much 
 smaller spermatic arteries near the peritoneal or vaginal ring through 
 which they, together with the ductus deferens or spermatic duct, pass to 
 the testes. Trace the right spermatic vein to the posterior vena cava, 
 and the left one to the left renal vein (or to the posterior vena cava, close 
 to the renal vein) ; also trace the spermatic arteries to their respective 
 places of origin — the right spermatic artery, from the A. mesenterica 
 posterior and the left one from the aorta a little cephalad of the preced- 
 ing; sometimes both of these arteries arise from the aorta close to the A. 
 mesenterica posterior. In the female the utero-ovarian arteries correspond 
 to the spermatic arteries but are much shorter. Each artery passes in a 
 tortuous manner between the two peritoneal layers of the anterior part 
 of the broad ligament of the uterus and divides into two branches of 
 which one is distributed to the ovary and the other to the cornu of the 
 uterus. Clean up the aorta (and vena cava) taking care not to remove the 
 lumbar lymph glands which lie near the place where the aorta divides into 
 the Aa. iliaca externa and interna, (sometimes spoken of as the terminal 
 branches of the aorta) (PL V, 30, 34). Note the size, number and location 
 of the lumbar lymph glands. The posterior portion of the body should 
 now be divided into halves by a sagittal section through the Ivimbar and 
 sacral vertebrae, the pelvic symphysis and the pelvic organs. Identify 
 each lumbar and sacra vertebra. Identify also the trunk of the sympa- 
 thetic nerve which, in this region, lies on the ventro-lateral face of the 
 bodies of the vertebrae and is covered by the aorta and the posterior vena 
 cava (PI. V, 45). This nerve trunk and its connections with each of the 
 lumbar and sacral nerves, by the rami communicantes, should be noted 
 as the dissection of the lumbo-sacral nerve plexus proceeds. 
 
 A. circumfiexa iliaca (PI. V, 29) usually arises from the A. iliaca externa, 
 
 close to its origin, but sometimes directly from the aorta. It extends 
 laterally across the ventral surface of the psoas muscles and divides into 
 an anterior and a posterior branch shortly before it reaches the pos- 
 terior border of the M. transversus abdominis. Transect the transversus 
 abdominis near the middle of its fleshy portion and turn it aside. Note 
 the location and size of the external iliac lymph glands (PI. V, 64) which 
 
28 
 
 are situated near the bifurcation of the A. circumflexa iliaca. Dissect up 
 the peritoneum cephalad of the peritoneal or vaginal ring and note very 
 carefully the relation of this ring and the spermatic cord, to the posterior 
 edge of the M. obliquus internus. Do not confuse the M. cremasteric 
 externa with the obliquus internus. Transect the obliquus internus a little 
 dorsal to the peritoneal ring. Now trace the anterior branch of the A. 
 circumflexa iliaca. At, or near, its origin it may give off one or two small 
 branches to the psoas magnus and iliacus. About 5 cm. from its origin 
 this anterior branch divides into two branches which are distributed to 
 the Mm. transversus, abdominis obliquus internus and obliquus externus. 
 The posterior branch of the A. circumflexa iliaca, 5 to 8 cm. from its origin, 
 also divides into two branches of which one goes to the obliquus internus 
 and the other, after perforating the abdominal wall near the external angle 
 of the ilium, runs downward on the inner face of the M. tensor fasciae latae, 
 about 5 cm. from its anterior border, and is distributed to the panniculus, 
 the precrural or subiliac lymph gland and to the inner face of the tensor 
 fasciae latae. To demonstrate this latter branch reflect the skin in the 
 region of the flank and dissect between the abdominal wall and the inner 
 face of the tensor fasciae latae. Find the artery (and vein) on the inner 
 surface of the tensor fasciae latae, 5 to 8 cm. from its anterior border, and 
 trace it in both directions. 
 
 Internal inguinal ring. 
 
 The internal inguinal ring should not be confused with the small peri- 
 toneal or vaginal ring of the male. The internal inguinal ring is from 10 
 to 12 cm. in length, measured from the prepubic tendon to the dorsal margin 
 of the peritoneal ring. The anterior boundaiy of the internal inguinal 
 ring is formed by the posterior edge of the M. obhquus internus; the pos- 
 terior boundary is formed by the inguinal ligament. In the male the follow- 
 ing structures pass through the inguinal canal, viz., the evaginated peritoneum 
 of the spermatic cord, the ductus deferens or spermatic duct, the spermatic 
 nerves, artery and vein and lymph vessels, the A. pudenda externa and 
 the M. cremasteric externa. The skin in the region of the external inguinal 
 ring should now be carefully turned aside in order to expose the superficial 
 inguinal lymph gland, the external inguinal ring and the structures which 
 pass through it. The superficial inguinal lymph gland forms a large mass, 
 8 to 10 cm. long, which lies anterior to the external inguinal ring. In the male 
 the gland extends along the course of the A. abdominalis subcutanea on 
 either side of the penis ; in the 'female the gland is situated between the 
 mammary gland and the abdominal wall. Now turn aside the portion of 
 the M. obliquus internus that forms the anterior boundary of the internal 
 
29 
 
 inguinal ring and note that the space (i.e. the inguinal canal) occupied by 
 the spermatic cord is bounded posteriorly by the inguinal ligament and 
 anteriorly, by the M. obliquus internus; note also that the length of the 
 canal from the external inguinal ring to the level of the peritoneal ring, 
 measured along the spermatic cord, is about lo cm. 
 
 A. iliaca externa (PI- V, 30) arises from the aorta at the level of the ^pn 
 lumbar vertebra and extends obliquely ventrally, at the side of the pelvic 
 inlet, to the level of the anterior edge of the pubis where it is continued 
 as the A. femoralis. Remove the overlying peritoneum and fascia. Note 
 that the large V. iliaca externa is immediately posterior to the artery. The 
 termination of the A. iliaca externa and the beginning of the A. femoralis 
 is indicated by the truncus pudendo-epigastricus or prepubic artery. 
 
 Truncus pudendo-epigastricus or prepubic artery (Pl.V, 31) is only6to8cm. 
 in length. It arises from the A. iliaca externa near the level of the anterior 
 border of the pubis. The artery crosses the dorsal or free edge of the 
 inguinal ligament and extends for a short distance along the abdominal or 
 anterior face of the ligament to the internal inguinal ring where it divides 
 into two branches — A. epigastrica caudalis or posterior abdominal and A. 
 pudenda externa or external pudic. 
 
 (i) A. epigastrica caudalis (or posterior abdominal). 
 
 This branch of the pudendo-epigastric trunk extends cephalad along 
 the lateral border of the M. rectus abdominis to which it is principally dis- 
 tributed; small twigs however, are also supplied to the transversus ab- 
 dominis and the obliquus internus. The artery is accompanied by a vein. 
 
 (2) A. pudenda externa (or external pudic). 
 
 This artery and its branches may be readily exposed by dissecting, 
 en masse, the sheath and penis from the abdominal wall as far back as to 
 the external inguinal ring taking care not to cut the artery as it emerges 
 from the ring at the postero-internal commissure. 
 
 The A. pudenda externa is from 4 to 6 cm. in length. Immediately after 
 it passes through the external inguinal ring it divides into two branches— 
 the A. abdominalis subcutanea and the A. dorsalis penis. Trace the former 
 cephalad, along the side of the sheath, to which and to the superficial inguinal 
 lymph gland it is distributed. The dorsal artery of the penis passes to the 
 dorsum of that organ and terminates at the glans penis. It gives off col- 
 lateral branches to the corpus cavernosum one of which usually passes 
 posteriorly and anastomoses with a branch of the A. obturatoria. In the 
 female the mammary artery takes the place of the dorsal artery of the penis. 
 Note that the enormous venous plexus on the dorsal and lateral sides of the 
 
30 
 
 penis, (or the mammary glands) is drained mainly by the large V. pudenda 
 externa (PL V, 42), which lies in the subpubic groove of the pelvis. 
 
 A. pudenda interna (PI. V, 37). 
 
 Care must be exercised in tracing this artery especially its distal half, not 
 to injure its numerous small branches or the neighboring nerves; the adjoin- 
 ing veins however, may be cut if desired. The urocyst and all of the other 
 pelvic organs should be turned dorsally. The A. pudenda interna arises 
 from the A. iliaca interna near the origin of the latter vessel. It extends 
 posteriorly across the lateral wall of the pelvic cavity, lying close to the 
 dorsal border of the iliac portion of the M. obturator internus. Opposite 
 the superior ischiatic spine the artery is covered by the M. retractor ani 
 which should be transected and turned aside (PI. V, 21 and 21'). Near the 
 lesser sacro-sciatic foramen the artery either passes through the sacro- 
 sciatic ligament i.e. from its inner to its outer surface, or is imbedded in the 
 substance of the ligament. Trace the artery peripherally as far as can 
 be done readily (to the posterior border of M. retractor ani) and then 
 proceed as follows: make a circiilar cut in the skin of the anal region at a 
 little distance, 4 to 6 cm., from the anal orific; also cut the large bundle of 
 muscle fibres (recto coccygeal, PL V 23) that attaches the terminal part of 
 the rectvun to the coccygeal vertebrae. Cut also, the M. retractor penis 
 (PL V, 22). Now carefully remove the connective tissue from the side of 
 the anus vintil the artery and nerves are exposed. The main trunk of the 
 artery terminates in the erctile tissvie at the root of the penis. 
 
 Branches of the A. pudenda interna. 
 
 (i) A. umbilicalis (PL V, 39) arises from the pudenda interna 2 to 3 cm. 
 from the origin of that vessel and passes directly to the urocyst. Before 
 birth the A. umbilicalis is a very large vessel and carries the foetal blood 
 to the placenta. After birth the vessel extends only to the urocyst and is 
 very mvich smaller than in foetal life. 
 
 (2) A. haemorrhoidalis media (or vesico-prostatic) . This small artery 
 in the male, arises from the pudenda interna about 8 cm. from the origin 
 of the latter (or about half way between the origin of the A. pudenda 
 interna and the anterior edge of the M. retractor ani) and runs posteriorly. 
 It supplies small twigs to the rectum, urocyst, prostate gland, and seminal 
 vesicle. Near the ischial arch the A. pudenda interna gives off a small 
 branch — A. perinei — which passes somewhat dorsally at the side of the 
 anus which it supplies; the A. pudenda interna also gives off twigs to the M. 
 bulbo-cavemosus and the skin of the perineum. In the female the corres- 
 ponding artery is much larger and gives off the A. uterina caudalis. This 
 
31 
 
 runs cephalad on the side of the vagina to which it gives branches and 
 ramifies on the body of the uterus, anastomosing with the anterior and 
 middle uterine arteries. 
 
 N. femoralis (PL V, 46, PI. VII, 14) originates from the ventral divisions of 
 the 3d, 4th, 5th and 6th lumbar nerves; very commonly however, the branch 
 from the 6th lumbar nerve is wanting. Turn aside or remove the iliac 
 fascia from the ventral surface of the sublumbar mtiscles. The proximal 
 portion of the N. femoraUs is covered by the M. psoas parvus. Transect 
 this muscle a little caudal to the A. circumflexa iliaca and turn its distal 
 portion toward the median plane. The large N. femoralis will now be 
 seen to have the same general direction ventro-caudally, as the A. ihaca 
 externa. Transect the psoas magnus at the same level as the psoas parvus; 
 separate the two muscles from each other sufficiently to trace the N. femoral- 
 is to its respective places of origin from the 3d, 4th, 5th, and 6th, if present, 
 lumbar nerves (PL V, in, iv,. v). Near its origin the N. femoralis lies at 
 about the same level as the A. iliaca externa. At the ventral border of the 
 tendon of the psoas parvus where the nerve passes under the anterior end of 
 the M. sartorius (PL V, 11), the nerve Hes just anterior to the artery but is 
 separated from it by the tendon of the psoas parvus which lies between the 
 artery and the nerve (PL V, 8')- 
 
 Branches of the N. femoralis. 
 
 The first branch of the N. femoralis is given oft" a little peripheral to 
 the place of junction of the ventral divisions of the 3d, and 4th lumbar 
 nerves. It is a small branch supplied to the psoas magnus. The next 
 branch, much larger than the preceding, leaves the N. femoralis a little 
 peripheral to the junction of the 4th and 5th lumbar nerves. This second 
 branch extends laterally between the psoas magnus and the iliacus and 
 divides into several branches which are distributed to the M. iliacus; one 
 or more small filaments may go to the psoas magnus. The remaining 
 portion of the N. femoralis may be exposed as follows: Cut the femoral 
 aponeurosis near its attachment to the M. obliquus extemus and remove it. 
 With the fingers, principally, dissect between the muscles of the thigh and the 
 posterior face of the inguinal ligament, leaving the ligament intact. Identify 
 the M. sartorius and note its relation, together with that of the iliacus and 
 the psoas magnus, to the ingviinal ligament. Free the sartorius from its 
 attachment to the iUac fascia. Dissect between the sartorius and the 
 M. gracilis taking care not to injure the nerve and blood-vessels that 
 emerge from between these two muscles near the middle of the thigh. 
 Transect the sartorius near the middle of the thigh. Draw aside the 
 
32 
 
 proximal portion of the muscle taking care not to cut the small nerve 
 branches it receives from the N. saphenus internus (PI. V, 47, 48) (a branch 
 of the N. femoraKs) which lies immediately beneath the proximal half of 
 the sartorius; also do not disturb the deep inguinal lymph gland which 
 lies in the interstice between the sartorius and the pectineus (PI. V, 63). 
 As the N. femoralis crosses the tendon of the psoas magnus it gives off the 
 large branch just mentioned, N. saphenus internus, which runs beneath 
 the sartorius for about one-half the length of the muscle, supplies small 
 branches to it, as just stated. It then emerges with the A. and V. saphena 
 interna, from between the adjacent borders of the sartorius and gracilis, 
 near the middle of the thigh, where it breaks up into several large sub- 
 cutaneous branches which are distributed to the inner and anterior faces 
 of the thigh and leg. The longest of these branches accompanies the 
 A. and V. saphena interna to the flexor side of the tarsus. Frequently the 
 N. saphenus internus is divided into two parallel branches. After giving 
 off the N. saphenus internus the main trunk of the N. femoralis, together 
 with a large artery and vein, passes between the rectus femoris and the 
 vastus internus into the quadriceps femoris group of muscles. Dissect 
 between the vastus internus and the rectus femoris; transect the rectus 
 femoris 10 to 15 cm. from its attachment to the patella and reflect the 
 ends. The vastus internus also may be partially transected, if desired. 
 Now trace the N. femoralis to its termination in the rectus femoris, vastus 
 internus, vastus externus, and vastus intermedivts. The small M. capsu- 
 laris is not supplied l:>y this nerve but by one of the gluteal nerves as 
 mentioned later. 
 
 Exposure of the A. iliaca interna, the A. sacralis lateralis and the sacral 
 nerves (PI. V, 34, 35, 52, 54, 55, 56, 57, 60). 
 
 Turn the rectum and other pelvic organs ventrally and find the small 
 nerves (PI. V, 58) 2 to 4 in number, which lie between the peritoneum and 
 the sacro-sciatic ligament and extend from the 2d, 3d, and 4th or from the 
 3d and 4th only, sacral nerves towards the lateral side of the pelvic organs 
 where, in connection with branches of the sympathetic nerve, they form 
 an intricate network of nerves known as the hypogastric or pelvic plexus 
 (PL V, 51). (If put on the stretch these two or more small nerves will 
 stand out as more or less tense bands.) Great care must be exercised in 
 exposing the A. (and V.) sacralis lateralis and the sacral nerves, because 
 of their intimate relation to each other and to the sacro-sciatic ligament. 
 Cut the ligament along the ventral mid surface of the V. sacralis lateralis 
 and carefully turn it from the vein. It will now be seen that the largest 
 of the sacral nerves, N. ischiadicus, 5 to 8 cm. in width (PL V, 54), originates 
 from the 5th and 6th lumbar and the ist and 2d sacral nerves. This large 
 
33 
 
 nerve trunk lies on the outer or lateral surface of the sacro-sciatic ligament 
 and is not very liable to be mutilated. Two smaller nerves however, the N. 
 pudendus (PL V, 57) and the N. haemorrhoidalis (PL V, 60) which originate 
 from the 2d, 3d, and 4th or from the 3d and 4th, only, sacral nerves lie on 
 the inner or pelvic surface of the sacro-sciatic ligament or else are imbedded 
 in its substance. Each of these two nerves is from one-half to one centi- 
 meter in width but is so thin, and in color so closely resembles the liga- 
 ment that it is liable to be overlooked and removed along with the 
 ligament. 
 
 A. iliaca interna (PL V, 34) is a very large vessel and arises from the aorta 
 close to the intervertebral disc between the 5th and 6th lumbar vertebrae. 
 It runs under the wing or transverse process of the sacrum, then turns 
 ventrally and extends along the pelvic surface of the shaft of the ilium to 
 near the psoas tubercle of the ilium, where the vessel divides into its two 
 terminal branches — the A. circumfiexa femoris lateralis (iliaco-femoral 
 artery) and the A. obturatoria. To demonstrate this, remove a portion 
 of the overlying V. iliaca interna. 
 
 Branches of the A. iliaca interna. 
 
 (i) The last one of the six lumbar arteries arises from the dorsal side 
 of the A. iliaca interna and passes into the spinal canal through the inter- 
 vertebral foramen between the last lumbar vertebra and the sacrum. 
 
 (2) A. pudenda interna (PL V, 37), already described. See p. 30. 
 
 (3) A. sacralis lateralis (PL V, 35). Remove the overlying V. sacralis 
 lateralis. The A. sacralis lateralis arises from the iliaca interna close to 
 the lumbo-sacral articulation. It extends along the sacrum ventral to the 
 sacral foramina and the nerves that emerge from them. At the third 
 sacral vertebra the artery divides into two branches — A. coccygeus lateralis 
 and the much larger A. glutea posterior. Trace the A. coccygeus lateralis 
 some distance along the tail to which it is distributed. The dissection 
 of the A. glutea posterior must be deferred until the gluteal nerves are 
 dissected. See p. 38. 
 
 (4) A. iliolumbalis arises at a right angle from the lateral side of the 
 iliaca interna, crosses the ventral surface of the ilium beneath or dorsal to 
 the Mm. psoas magnus and iliacus to which it gives small branches. Tran- 
 sect the M. iliacus opposite the artery. Draw aside the iliacus and the 
 psoas magnus and trace the artery to where it crosses the external border 
 of the ilium a little behind the external angle. Its terminal branches which 
 will be demonstrated later, enter the gluteus niedius and the tensor fasciae 
 latae. 
 
 /> 
 
34 
 
 (5) A. glutea anterior is the largest branch of the iliaca interna. It 
 arises nearly opposite the iliolumbalis, passes through the greater sacro- 
 sciatic foramen and immediately enters the gluteal muscles by several 
 branches. These branches cannot be demonstrated until the gluteal 
 muscles have been dissected. Frequently one of the radicals of the N. 
 obturatoria (from the 6th lumbar, PI. VII, i6) crosses the ventral face of 
 the A. glutea anterior, close to its origin from the iliaca interna. 
 
 (6) A. circumflexa femoris lateralis (iliaco-femoral artery) is one 
 of the terminal branches of the iliaca interna. To expose the vessel, draw 
 aside the distal portion of the psoas magnus ; transect the iliacus and draw it 
 aside. The artery crosses the shaft of the ilium a little dorsal to the in- 
 sertion of the psoas parvus and enters the quadriceps femoris group of 
 muscles between the rectus femoris and the vastus externus. It supplies 
 branches to the psoas magnus and iliacus, rectus femoris, tensor fasciae 
 latae, vastus externus and medius and the superficial and middle gluteal 
 muscles. The artery is accompanied by two large veins. 
 
 (7) A. obturatoria (PI. V, 38) is the inner terminal branch of the A. 
 iliaca interna. It passes posteriorly on the inner or pelvic surface of the 
 shaft of the ilium along the ventral border of the iliac portion of the M. 
 obturator internus. The obturator vein and nerve accompany the artery. 
 At the anterior border of the obturator foramen the artery, vein and nerve 
 dip beneath the M. obtvirator internus (PL V, 18'). Cut the overlying 
 portion of this muscle close to its origin and turn it aside. In its course 
 beneath the M. obturator internus the artery gives off small twigs to it; 
 also a larger branch which passes through the obturator foramen and is 
 supplied to the hip joint. At the very posterior part of the obturator 
 foramen the obturator artery gives ofif a small branch which passes posteri- 
 orly on the dorsal surface of the ischimn, to the ischial arch, where it anasto- 
 moses with a branch of the A. obturatorius that extends along the ventral 
 face of the ischium; it also anastomoses by a small branch with the A. 
 pudenda interna. The extrapelvic portion of the A. obturatoria is deeply 
 covered by the muscles of the inner side of the thigh and can be only par- 
 tially exposed at present. First dissect the M. gracihs, beginning at its 
 posterior border; free it from the underlying muscles and at the same time 
 transect it a little below its middle. Turn back the proximal portion 
 of the muscle noting the blood-vessels and nerves that enter it. Now 
 beginning at its posterior border, cut the muscle about two-thirds of the 
 way across, close to its attachment to the pelvis, in order to expose clearly 
 the origin of the adductor magnus. (The adductor magnus as here used 
 includes the adductor parvus of some writers). Note the deep inguinal 
 lymph gland 12 to 15 cm. in length, that lies in the space between the 
 
35 
 
 sartorius and the pectineas (PI. V, 63). Note the relation of this gland 
 to the large artery (A. femoralis) beneath it and to the inguinal ligament. 
 Dissect between the pectineus and the £idductor magnus, on one side, and 
 the deep inguinal lymph gland and the A. and V. femoralis, on the other. 
 Transect the pectineus a little below its middle and draw aside the distal 
 portion. Carefully remove any connective tissue or fat from the space 
 between the pectinevis and the adductor magnus and find the small nerves 
 that enter each of these muscles. Dissect between the adductor magnus 
 and tlic semimembranosus; transect the adductor magnus close to its 
 pelvic attachment and draw up the muscle sufficiently to expose the M. 
 obturator externus which is directly beneath the proximal portion of the 
 adductor magnus. Find the A. obturatoria (and large vein) where it emerges 
 from beneath the posterior border of the M. obturator externus, close to 
 the ventral surface of the ischium. The posterior portion of the M. 
 obturator externus must now be cut close to its origin and drawn aside in 
 order to expose the A. obturatoria, after it passes through the obturator 
 foramen. About 5 cm. from the posterior edge of the foramen the artery 
 gives ofif a large branch which runs along the ventral surface of the ischium 
 to the ischial arch where it divides into several branches, of which one goes 
 to the crus penis close to its attachment to the ischium. The extrapelvic 
 portion of the A. obturatoria also gives off a branch to the ventral surface 
 and one to the dorsal surface of the penis. About 5 cm. peripheral to these 
 two branches a much larger branch is given off to the semimembranosus. 
 Further dissection of the obturator artery must be deferred until the over- 
 lying muscles have been dissected. 
 
 N. obturatorius ( Pl.V, 49; PI, VII, 16) originates from the 4th and 5th lumbar 
 
 nerves; frequently however, it receives a branch from the 6th lumbar 
 nerve. The nerve extends directly to the anterior part of the obturator 
 foramen. It lies just beneath the peritoneum and for some distance accom- 
 panies the obturator artery and vein; the nerve and blood-vessels then 
 diverge from each other, the nerve passing through the anterior part of 
 the obturator foramen and the blood-vessels through the posterior part. 
 Reflect the proximal portion of the M. gracilis and the large branch of the 
 N. obturatoris that supplies it will be seen on the proximal portion of the 
 muscle extending transversely toward its posterior border. Upon drawing 
 aside the proximal portion of the M. pectineus the branches of the N. 
 obturatorius to it and to the adductor magnus may be seen. Upon 
 drawing the adductor magnus from the obturator externus the branch 
 of the obturator nerve that passes through the M. obturator externus, 
 near its anterior border, and enters the adductor magnus, may be seen. 
 
36 
 
 Turn aside or remove a portion of the obturator externus and trace the 
 respective branches suppHed to it and to the adductor niagnus, the gracilis, 
 and pectineus to their respective places of origin from the obturator nerve. 
 It will now be seen that N. obturatorius divides into two branches one of 
 which is distributed to the gracilis and pectineus and the other to the 
 adductor magnus and obturator externus. 
 
 N. pudendus (PI. V, 57, 57') originates from the 2d and 3d sacral nerves, or in 
 some cases from the 3d only. It extends posteriorly, at first on the inner or 
 pelvic surface of the sacro-sciatic ligament, but gradually passes into the 
 substance of the ligament. Near the lesser sciatic foramen the nerve 
 crosses the lateral surface of the A. pudenda interna, (PL V, 37), and 
 inclining inwards, turns around the ischial arch and gains the dorsal surface 
 of the penis along which it continues as the N. dorsalis penis. vShortly 
 before the nerve crosses the A. pudenda interna it gives off the N. haemor- 
 rhoidalis medius, or perinaeo-anal nerve (PL V. 57") which is distributed 
 by numerous branches to the muscles of the urethra and penis, including 
 the ischio-cavernosus muscle, -and to the terminal portion of the rectum. 
 The communicating branch of the posterior ventral gluteal nerve (PL V, 55) 
 to the N. pudendus joins the latter at the place of origin of the perinaeo-anal 
 nerve. In the female the N. pudendus is distributed to the labia, clitoris, 
 and the constrictor muscles of the vulva and anus and to the perineum. 
 
 N. hemorrhoidalis (PL V, 60) is formed from the 3d and 4th sacral nerves 
 or from the 4th ,only. It passes posteriorly on the inner or pelvic face 
 of the sacro-sciatic ligament to the anal region where it divides into a 
 number of branches which are distributed to the retractor and sphinctor 
 muscles of the anus and to the skin of the perineal region. 
 
 A. profunda femoris arises either in common with the truncus pudendo- 
 epigastricus (or prepubic) or a little peripheral to it. It passes caudo- 
 ventrally between the pectineus and the terminal tendon of the iliacus 
 and psoas magnus. Draw aside the pectineus and demonstrate the one 
 or more small branches supplied to it. Beneath the adductor magnus the 
 artery gives off a very large branch which is distributed to this muscle, and 
 to the gracilis and the semimembranosus. It also supplies twigs to 
 the deep inguinal lymph gland. The remaining portion of the A. profunda 
 femoris is covered by muscles and cannot be traced at present. A large 
 vein accompanies the artery. 
 
 A. femoris anterior (Pl.V, 32) arises from the A. femoralis about 2 cm. peripheral 
 to the femoris profunda, from the opposite side of the A. femoralis. It passes 
 
37 
 
 anteriorly and enters the precural group of muscles between the rectus 
 femoris and vastus internus. It supplies branches to the iliacus and the 
 quadriceps femoris muscles. 
 
 Exposure of the gluteal vessels and nerves. 
 
 Remove the skin from the gluteal and femoral regions. Dissect be- 
 tween the biceps femoris and the adjoining mviscles, viz., the gluteus superfi- 
 cialis and vastus extemus, anteriorly, and the semitendinosus, posteriorly. 
 Also dissect between the semitendinosus and the semimembranosus. Tran- 
 sect the semitendinosus opposite the ischial tuberosity and draw aside the 
 proximal portion just enough to expose the nerve and blood-vessels that 
 enter it immediately dorsal to the ischial tuberosity (PI. IV, 25). Transect 
 the biceps femoris at the level of the external small trochenter and also at the 
 level of the nerve, just exposed, to the semitendinosus, i.e. immediately 
 dorsal to the ischial tuberosity. In this latter transection one of the large 
 nerve branches to the biceps femoris will probably be cut; the other large 
 nerve branch to this muscle lies more deeply and may be seen readily if the 
 proximal portion of the muscle be drawn aside. Trace both of these 
 large branched peripherally for some distance. Upon drawing aside the 
 proximal portion of the biceps femoris it will be seen that the two or three 
 large branches just mentioned (and the A. and V. glutea posterior) emerge 
 from beneath the gluteus medius and are distributed to the biceps femoris 
 and also one small branch to the posterior border of the gluteus super- 
 ficial is (PI. IV, 23). These large nerve branches cannot be traced at present 
 to their place of origin from one of the posterior gluteal nerves. Now 
 dissect between the tensor fasciae latae and the gluteus superficialis taking 
 care not to cut the nerve or blood-vessels that emerge from beneath the 
 anterior edge of the gluteus superficiahs near its middle, and enter the 
 adjoining borders of the tensor fasciae latae and the gluteus superficialis 
 (PI. IV, 22). Transect the gluteus superficialis a little proximal to the 
 nerve just exposed, turn it aside somewhat, and note the small nerves and 
 blood-vessels supplied to its anterior edge. The gluteus medius should 
 now be transected a little proximal to the two above mentioned nerves 
 that emerge from beneath the respective anterior and posterior borders 
 of the muscle, i.e. the nerve to the tensor fasciae latae and the nerve to 
 the biceps femoris (PI. IV, 22,23). The deep face of the gluteus medius is 
 indicated by these two nerves and they shoidd be kept in view while transect- 
 ing the muscle; this maybe done if while transecting it, the proximal portion 
 of the muscle be freed largely from its attachment to the iliac fossa and the 
 sacrum and turned back. Note the vein and artery — A. iliolumbalis — 
 that cross the external border of the ilium from 5 to 8 cm. ventral to the 
 
38 • 
 
 external angle of the ilium and are distributed to the gluteus medius and 
 tensor fasciae latae. See p. 33. 
 
 A. glutea anterior. The distribution of the A. glutea anterior to the mid- 
 dle and deep gluteals may now be demonstrated. The artery will have 
 been cut when the gluteus medius was turned back. Clean up the artery 
 in so far as it can be traced. See p. 34. 
 
 A. glutea posterior or ischiadicus (continued, see p. 33). The distribu- 
 tion of the A. glutea posterior to the biceps femoris, the semitendinosus 
 and, in this specimen, to the internal part of the gluteus superficialis, may 
 now be demonstrated. 
 
 Nn. glutei. There are 5 or 6 of these nerves which are usually described 
 as the anterior and posterior gluteal nerves. 
 
 Nn. glutei anterior. There are three or four nerves in this group. They 
 pass through the great sciatic foramen and are distributed to the gluteal 
 and other muscles as follows: one large nerve lying at the .anterior side 
 of the N. ischiadicus passes postero-laterally across the dorsal surface of 
 the shaft of the ilium and between the middle and deep gluteal muscles 
 and is distributed to the tensor fasciae latae and the gluteus superficialis as has 
 been already demonstrated (PI. IV, 22). Sometimes this nerve sends a 
 small branch to the gluteus medius. A short distance from its origin it 
 frequently gives one or more short branches to the gluteus profundus; 
 a branch from this nerve is also sent to the M. capsularis. The other large 
 anterior gluteal nerves have a very short course before entering ihe gluteus 
 medius ; they arise from the lateral side of the plexus but are so completely 
 hidden from view by the great N. ischiadicus that they are liable to be 
 overlooked. They accompany the A. ghitea anterior through the great 
 sciatic foramen and immediately enter the gluteus medius. 
 
 Nn. glutei posterior (PI. V, 55, 56). There are two large nerves in 
 this group, a dorsal or superior, and a ventral or iiiferior nerve, both of 
 which apparently arise from the dorso-caudal side of the N. ischiadicus. 
 The one first given oiT, the posterior dorsal gluteal (PI. V, 56), really has 
 its origin from the 6th kimbar and the i st and 2d sacral nerves ; only a few 
 fibres however come from the 6th. The nerve extends posteriorly between 
 the sacro-sciatic ligament and the gluteus medius and upon emerging from 
 beneath the latter muscle it extends between this muscle and the biceps 
 femoris to which it is distributed as has already been demonstrated (PI. IV, 
 23). One small branch from this nerve is sometimes supplied to the gluteus 
 
39 
 
 medius and one to the posterior edge of the gluteus superficiaUs. The 
 second posterior gluteal nerve, posterior ventral gluteal, originates from the 
 1st and 2d sacral nerves but to a very slight extent however, from the 1st 
 sacral. This nerve also passes posteriorly between the sacro-sciatic liga- 
 ment and the M. gluteus medius. Eight or ten centimeters from its origin 
 it divides into two branches of which one enters the semitendinosus im- 
 mediately dorsal to the ischial tuberosity as already demonstrated (PI. IV, 
 25). This branch of the posterior gluteal nerve gives off a filament that 
 unites with the N. pudendus as already demonstrated. The other branch 
 of the posterior ventral gluteal nerve emerges near the middle of the outer 
 surface of the ischial tuberosity and may be seen between the biceps femoris 
 and the semitendinosus, upon turning aside the latter muscle (PI. IV, 25'); 
 it is distributed subcutaneously to the region just below the ischial tubero- 
 sity. In addition to the gluteal nerves already mentioned there is given 
 off from the N. ischiadicus another small nerve which extends nearly par- 
 allel to the N. ischiadicus and is distributed to the M. gluteus profundus. 
 Sometimes this small nerve originates from the gluteal nerve that supplies 
 the tensor fasciae latae and the gluteus superficialis. 
 
 A. profunda femoris (continued). 
 
 Draw out the middle one of the three portions into which the biceps 
 femoris has been cut and note the large A. profunda femoris (and veins) 
 that enters the muscle a little above the level of the external small tro- 
 chanter (PI. IV). Cut the vessels, turn back this portion of the muscle as 
 far as possible and trace the artery to its distribution in the biceps femoris 
 principally; small twigs are supplied to the gluteus medius, the quadratus 
 femoris and the adductor magnus. 
 
 A. obturatoria (continued). 
 
 Remove piecemeal a portion of the semimembranosus and trace the 
 artery to this muscle; one or more branches go to the semitendinosus and 
 one to the biceps femoris. 
 
 Nerves to the Mm. gemelli, obturator internus and quadratus femoris. 
 
 Place the specimen with the gluteal region uppermost, clean up the 
 N. ischiadicus (PI. IV, 26) and identify the following muscles — the gemelli, 
 the tendon of the obturator internus and the quadratus femoris. The 
 one or two small nerves that supply these muscles originate from the deep 
 or internal face of the N. ischiadicus at nearly the same level as the posterior 
 ventral gluteal nerve and lie between the N. ischiadicus and the sacro- 
 sciatic ligament so that in order to see them the N. ischiadicus must be 
 
40 • 
 
 drawn aside. Near the posterioi: border of the M. gluteus profundus the 
 small nerve to the gemelli, etc., (in cases where only one nerve is present), 
 gives off a small branch which passes through the lesser sciatic foramen 
 into the pelvic cavity where it divides into two branches one of which 
 extends anteriorly along the surface of the iliac portion of the M. obturator 
 internus to which it is distributed; the other branch supplies the other 
 head of the obturator internus (PI. V, 50). The main nerve itself crosses 
 the deep or internal face of the gemelli and the tendon of the obturator internus, 
 supplies branches to the gemelli and may be seen again at the posterior 
 border of this muscle where it enters the adjoining quadratus femoris (PL 
 IV, 27). Demonstrate this by carefully separating the adjoining borders 
 of the gemelli and quadratus femoris in order to expose the nerve. The 
 gemelli and the tendon of the obturator internus may now be transected 
 in order to expose completely the nerve and its branches as above men- 
 tioned. 
 
 N. ischiadicus (PI. V, 54; PL IV, 26) arises from the 5th and 6th lumbar 
 and the i st and 2d sacral nerves ; occasionally it receives a branch from the 
 3d sacral nerve. It passes through the great sacro-sciatic foramen and 
 between the sacro-sciatic ligament and the M. gluteus medius, crosses a 
 portion of the gluteus profundus, the gemelli and the tendon of the obturator 
 internus and the quadratus femoris. Near the level of the gemelli the 
 N. iscMiadicus divides into two terminal branches — peronaeus communis 
 and N. tibialis (PL IV, 29, 34). (It should be kept in mind that the N. 
 ischiadictis and its branches are named differently by different authors. 
 The names here given are the names used in the more recent text books of 
 anatomy and are the terms recommended by the various National Ana- 
 tomical Societies.) In the femoral region the Nn. peronaeus communis 
 and tibialis are surrounded by the biceps femoris, the adductor magnus 
 and the semimembranosus. Near the level of the gemelli there is given off, 
 either from the N. ischiadicus or from the N. tibialis, a large fasciculus 
 which extends somewhat posteriorly and supplies the biceps femoris, semi- 
 tendinosus and semimembranosus (PL IV, 28). Demonstrate, by dissect- 
 ing between the biceps femoris and the semitendinosus and between the 
 semitendinosus and the semimembranosus. Transect the semitendinosus 
 at the level of the 3d trochanter and trace the nerve branches to their 
 respective muscles. 
 
 N. peronaeus communis (PL IV, 29). The distal portion of the biceps 
 femoris must now be turned aside, noting the blood-vessels, which must 
 be cut, that enter the muscle and also the small nerve — peronaeal cutaneous 
 (PL IV, 30, 30') — a branch of the N. peronaeus communis. This small 
 
41 
 
 branch appears to go to the biceps femoris but in reaUty it passes through 
 the muscle and is distributed subcutaneously to the external face of the 
 tibial region. The large N. peronaeus communis is given ofif from the 
 N. ischiadicus at the level of the gemelli muscle; it hes at the side of the 
 N. tibialis until it reaches the M. gastrocnemius where it diverges from the 
 N. tibialis and passes between the external head of this muscle and the 
 biceps femoris (PL IV, 29). Beginning at the posterior border of the biceps 
 femoris slit the tibial aponeurosis lengthwise the tibia and turn aside the 
 aponeurosis and the distal end of the biceps femoris (PL IV, 10', 11'). 
 Now trace the N. peronaeus communis to the place where, between the 
 M. peroneus (or lateral digital extensor) and the extensor pedis, it dips into 
 the anterior tibial group of muscles. Shortly before the nerve enters these 
 muscles it divides into two terminal branches — the N. peronaeus super- 
 ficialis and the N. peronaeus profundus (PL IV, 32, 33). The N. peronaeus 
 superficialis is much the smaller of the two and is for the most part sub- 
 aponeurotic. Near its origin it gives off a muscular branch to the M. 
 peroneus or lateral digital extensor (PL IV, 32') ■ Trace the superficial or 
 subaponeurotic portion of the nerve (PL IV, 32") to its place of distribu- 
 tion near the middle of the metatarsus. Note the relation of the nerve to 
 the extensor pedis, peronaeus and to the tibial aponeurosis. 
 
 N. peronaeus profundus (PL IV, 33). Just as this nerve passes between 
 the extensor pedis and peroneus it divides into several branches of which 
 all but one are distributed to the extensor pedis and the tibialis anterior 
 (PL VI, 34). Cut the extensor pedis below the middle of the tibia and draw 
 it aside. The remaining branch of the peronaeus profundus lies deeply 
 between the extensor pedis and the tibialis anterior (PL VI, 34')- In 
 tracing this branch to its termination in the digital region the tendons of 
 the extensor pedis and peroneus may be cut near the middle of the metatar- 
 sus and drawn aside. As the nerve crosses the tarsus it gives off several 
 small branches to this region and to the M. extensor digitalis brevis. At 
 the tarsus the nerve divides into two main portions of which one accompanies 
 the A. metatarsea dorsalis (lateralis) to the region of the fetlock (PL VI, 
 35) ; the other portion of the nerve extends obliquely across the anterior 
 face of the large metatarsal bone and may be traced as far as the fetlock 
 and often even beyond that joint. 
 
 N. saphenus externus arises from the N. tibialis at the level of the third 
 trochanter (PL IV, 35; PL VI, 36). It extends along the postero-external 
 part of the gastrocnemius, accompanied by a vein, to near the beginning 
 of the tendo Achillis. At this point it occasionally receives a small 
 
42 
 
 accessory branch from the N. peronaeus communis (PI. VI, 31). The N. 
 saphenus externus then gains the interval between' the tendo AchiUis 
 and the M. perforans and extends the length of this space, immediately 
 beneath the tibial aponeurosis, accompanied by the V. saphena externa. 
 Trace the nerve to its subcutaneous distribution at the outer face of the 
 tarsal and phalangeal regions (PI. VI, 36). 
 
 Demonstrate the popliteal Ijmiph gland, 6 cm. long by 2 cm. wide, in 
 the space between the biceps femoris and semitendinosus immediately 
 posterior to the gastrocnemius. 
 
 N. tibialis is the larger of the two terminal branches of the N. ischiadicus 
 (PI. IV, 34; PI. VI, 29). It lies beneath the biceps femoris until it reaches 
 the gastrocnemius. Just as it passes between the two heads of the gastroc- 
 nemius it gives off, anteriorily, a large fasciculus to the muscles on the 
 posterior side of the tibia (PI. VI). To demonstrate the branches of this 
 fasciculus carefully dissect up the external head of the gastrocnemius and 
 transect it a little below the middle of its fleshy portion taking care not to 
 cut the flexor perforatus which is partially embedded in the gastrocnemius 
 (PL VI, II, II', 12). The Nn. saphenus externus and peronaeus communis 
 shoi-dd also be left intact. The several branches of the fasciculus just 
 mentioned should now be traced to their respective muscles, viz., one branch 
 to the external head and one to the internal head of the gastrocnemius ; 
 a somewhat smaller branch to the flexor perforatus. Transect the perfora- 
 tus a little below the nerve supplied to it and draw aside the proximal part 
 of the muscle. Trace the remaining branches of the fasciculus to the 
 popHteus and flexor perforans (PI. VI). The N. tibialis passes between the 
 two heads of the gastrocnemius and for a short distance runs along the 
 posterior surface of the flexor perforatus; it then gradually crosses the 
 inner face of this muscle and accompanied by a small artery, descends to 
 the tarsus in the space at the inner side of the leg, between the tendo AchiUis 
 and the flexor perforans. Place the leg with its inner or medial surface 
 uppermost and expose the N. tibialis in this part of its course taking care 
 not to injure the one or more small arteries that accompany the nerve. 
 At the tarsus the N. tibialis divides into two terminal branches — the N. 
 plantaris medialis and the N. plantaris lateralis. Note very carefully the 
 relation of the N. tibialis to the internal saphena vein and artery and to the 
 tibial aponeurosis. 
 
 Nn. plantaris medialis and lateralis. These two nerves are the terminal 
 branches of the N. tibialis. They follow the tendon of the flexor perforans 
 through the tarsal sheath and, diverging somewhat from each other, descend 
 
43 
 
 the metatarsal region on either side of the j^erforans tendon. Eaeh nerve 
 is accompanied .by a slender artery (A. metatarsea plantaris superficialis) 
 and by a vein. The N. plantaris lateralis gives off a branch of consider- 
 able size to the proximal portion of the susix-nsorj' ligament. Near the 
 middle of the metatarsus, the N. plantaris medialis gives off a branch that 
 runs obliquely across the posterior face of the flexor tendons and joins 
 the plantaris lateralis a little above the distal end of the rudimentary 
 metatarsal bone. At the fetlock each plantar nerve divides into two or 
 three branches which are identical with those of the thoracic limb. 
 
 A. saphena. This sniall artery was noted when the N. saphenus intemus 
 (p. 32) was dissected. The artery arises from near the middle of the A. 
 femoralis. It extends along the inner or medial face of the thigh and leg 
 to near the tarsus where it anastomoses (usually) with a small recurrent 
 branch of the A. tibialis posterior. The artery is accompanied by the large 
 V. saphena. 
 
 A. femoralis. Turn aside the M. gracilis leaving intact the A. and V. 
 saphena. Transect the semimembranosus a hand's breadth (10 cm.) from 
 its attachment to the epicondyle of the femur and turn back the distal 
 portion of the muscle. Now trace the A. femoralis from its origin at the 
 level of the anterior border of the pubis to its termination just before it 
 passes between the two heads of the gastrocnemius where it is continued 
 by the A. poplitea. Note the muscles that are related to the artery, viz., 
 the sartorivis, pectineus, vastus intemus and adductor magnus. Note 
 also its relation to the deep inguinal lymph gland. 
 
 Branches of the A. femoralis. 
 
 (i) Pudendo-epigastricus or prepubic, see p. 29. 
 
 (2) A. profunda femoris, see p. 36. 
 
 (3) A. femoris anterior, see p. 36. 
 
 (4) Rami musculares, to the vastus internus, sartorius, gracilis, adduc- 
 tor magnus and semimembranosus. 
 
 (5) A. saphena, see above. 
 
 (6) A. nutritia femoris enters the nutrient foramen of the femur. 
 
 (7) A. genu (articular branch). This small branch arises from the 
 A. femoralis a little before the latter passes through the adductor magnus. 
 It rtuis near the posterior border of the vastus intemus to the inner or 
 medial surface of the femoro-tibial joint where it ramifies. It also gives 
 small twigs to the vastus intemus and the adductor magnus. 
 
 (8) A. femoris caudalis (or A. femoris posterior), is a large vessel which 
 arises from the caudal or posterior face of the A. femoralis, just before the 
 
.44 
 
 latter passes between the two heads of the gastrocnemius. Two or three 
 centimeters from its origin the A. femoris caudaHs divides into two branches 
 as may be seen upon turning aside the biceps femoris. (The external head 
 of the gastrocnemius may be partially transected close to its origin from 
 the femur.) One of the branches of the A. femoris caudalis passes upwards 
 or proximally, a short distance (4 to 6 cm.) between the semimem- 
 branosus and the biceps femoris and is distributed principally to the latter 
 muscle; it also gives off two branches, in this specimen, to the vastus 
 extemus. The other and larger branch of the A. femoris caudalis extends 
 downward and backward close to the posterior margin of the internal 
 head of the gastrocnemius and is distributed principally to the biceps 
 femoris and semitendinosus ; small branches are also supplied to the gastroc- 
 nemius and to the popliteal lymph gland. In the present specimen, about 
 I cm. peripheral to the A. femoris caudalis a small artery arises which passes 
 between the two heads of the gastrocnemius, immediately posterior to the 
 flexor perforatus, gives small branches to that muscle and to the perforans 
 and is continued as a slender vessel which accompanies the N. tibialis. 
 It unites with a small recurrent branch of the A. tibialis posterior a short 
 distance above the tarsus. In the present specimen, two additional arteries 
 originate from the A. poplitea about 4 cm. peripheral to the A. femoris cauda- 
 lis. The smaller of these two arteries goes to the external head of the gastroc- 
 nemius; the larger one is distributed to the distal portion of the biceps 
 femoris and the vastus extemus. The A. poplitea also gives off a small 
 branch to the internal head of the gastrocnemius. All the above arteries 
 are accompanied by veins. 
 
 A. poplitea is the direct continuation of the A. femoralis. It runs between 
 the tibia and the Mm. popliteus and flexor perforans as far as to the proximal 
 part of the tibio-fibular or interosseous space where it divides into the A. 
 tibialis posterior and the A. tibialis anterior. Cttt the M. popliteus a short 
 distance from its origin on the external epicondyle of the femur and draw 
 aside the muscle. Dissect between the M. peroneus and the flexor per- 
 forans. Insert the finger beneath the portion of the flexor perforans that 
 originates from the external tuberosity of the tibia and the adjoining portion 
 of the fibula and identify the tibio-fibular space (see skeleton). Taking 
 care not to injure the underlying artery, cut the perforans close to the 
 external tuberosity of the tibia and the adjoining portion of the fibula; 
 draw back the muscle and demonstrate the A. poplitea as mentioned above. 
 It gives ofl: a branch that enters the intercondyloid space of the femur and 
 supplies the femoro-tibial joint. 
 
 A. tibialis posterior is the smaller of the two terminal branches of the A. 
 poplitea. Begin the dissection of this artery near its peripheral end, i.e. at 
 
45 
 
 its S shaped curve on the medial side of the leg, anterior to the tuber calsis. 
 Turn back or remove the covering aponeurosis taking care not to cut the 
 A. and V. saphena, draw aside the small internal head of the flexor perforans 
 (M. flexor digitalis longus or flexor acessorius) and trace the artery as far 
 as possible, without cutting muscles, towards its origin. Now returning 
 to the origin of the artery, draw aside, and at the same time cut the flexor 
 perforans from its attachment to the posterior face of the tibia svifficiently 
 to expose the artery. 
 
 Branches of the A. tibialis posterior. 
 
 (i) Rami musculares to the Mm. popliteus and perforans. 
 
 (2) A. nutritia tibiae enters the nutrient foramen of the tibia. 
 
 (3) A. tarsea lateralis is a small branch which arises at the first flexure 
 of the sigmoid portion of the tibialis posterior. It runs between the tibia 
 and the flexor perforans and is distributed by several small branches to the 
 tendon and the lateral surface of the tarsus. 
 
 (4) One or more small branches from the convexity of the first ctu-ve 
 of the sigmoid portion of the artery to the medial surface of the tarsus. 
 
 (5) A. tibialis recurrens is a small artery which arises from the second 
 convexity of the sigmoid curve of the A. tibilias posterior. It extends 
 proximad along the N. tibialis and anastomoses with either the A. saphena 
 or with a branch from the A. femoris caudalis that accompanies the N. 
 tibialis. 
 
 (6) A branch given off from the second convexity of the sigmoid curve 
 passes between the tendo Achillis and the flexor perforans and is distributed 
 to the tendon and the region of the tuber calsis. The A. tibialis posterior 
 ends in two small terminal branches — the A. plantaris medialis and the 
 A. plantaris lateralis. 
 
 A. tibialis anterior. Dissect between the M. peroneus and the tibialis 
 anterior and draw aside the latter muscle. The A. tibialis anterior is the 
 larger of the two terminal branches of the A. poplitea. It passes through 
 the proximal part of the tibio-fibular arch and descends, with two large 
 veins, on the antero-lateral face of the tibia beneath the M. tibialis anterior. 
 At the tarsus the artery gives off the A. tarsea perforans which passes 
 through the tarsal canal and anastomoses with the two plantar arteries 
 or sometines with only the plantaris externus to form the arcus plantarus or 
 plantar arch. The trunk of the A. tibialis anterior is continued along the 
 metatarsus as the A. metatarsea dorsalis (lateralis). The A. tibialis 
 anterior supplies branches to the Mm. extensor pedis, tibialis anterior, and 
 several branches to the tarsal joint. Near its middle the A. tibialis anterior 
 gives off a variable branch — A. peronea — which descends along the fibula 
 
46 
 
 under the M. peroneus to which it suppKes small branches; it also gives 
 off a cutaneous branch. 
 
 A. plantaris medialis and A. plantaris lateralis. 
 
 These two small terminal branches of the tibialis posterior vary some- 
 what in different specimens. The following disposition however is common. 
 Each plantar artery descends with the respective plantar nerves, on either 
 side of the perforans tendon, to the proximal part of the metatarsus where, 
 between the flexor tendon and the suspensory ligament, they unite with the 
 A. tarsea perforans to form the arcus plantaris or plantar arch. The flexor 
 tendons should be cut and turned aside. Sometimes the A. plantaris 
 medialis does not join the plantar arch but is continued as the small satel- 
 lite vessel of the N. plantaris medialis. Four plantar metatarsal arteries 
 originate from the plantar arch. The two small superficial arteries, meta- 
 tarsea plantaris superficialis medialis and lateralis accompany the plantar 
 nerves on either side of the flexor tendons and unite with the A. metatarsea 
 dorsalis or with the corresponding digital arteries. Sometimes, as men- 
 tioned above, one of the superficial plantar metatarsal arteries is the direct 
 continuation of the A. plantaris medialis. Transect and draw aside the 
 suspensory ligament. 
 
 The two deep plantar metatarsal arteries, Aa. metatarsea plantaris 
 profundus medialis and lateralis, descend between the suspensory ligament 
 and the corresponding rudimentary metatarsal bones and unite near the 
 fetlock with the A. metatarsea dorsalis. Of the two deep metatarsal 
 arteries the medial or internal one is much the larger and supplies the 
 nutrient artery to the large metatarsal bone. 
 
 A. tarsea perforans arises from the A. tibialis anterior, passes through the 
 tarsal canal and luiites with the plantar arteries or with the external one 
 only, to form the plantar arch. 
 
 A. metatarsea dorsalis (lateralis) is the direct continuation of the A. tibialis 
 anterior. It crosses the anterior surface of the tarsal joint and descends, 
 at first, in the oblique vascular groove on the lateral face of the proximal 
 part of the principal metatarsal bone and then in the groove formed by 
 the principal and the lateral rudimentary metatarsal bones. Near the 
 distal end of the rudimentary metatarsal the artery passes between the 
 two bones and divides on the posterior face of the principal metatarsal, 
 between the two divisions of the suspensory ligament, to form the A. digitalis 
 medialis and the A. digitalis lateralis. These two arteries and their branches 
 are similar to those of the thoracic limb. 
 
PLATE IV 
 LATERAL SURFACE 
 
 1. External angle of ilium. 
 
 2. Tuber ischii. 
 
 3. External small or third trochanter. 
 
 4. Lateral epicondyle of femur. 
 
 5. M. obliquus abdominis extemus. 
 
 6. M. tensor fasciae latae with posterior edge drawn aside. 
 
 7. M. gluteus superficiaUs; (the gluteal apopeurosis has been removed). 
 
 8. M. gluteus medius. 
 
 9. M. gluteus profundus (in part.) 
 10, 10', II, 11'. M. biceps femoris. 
 
 12. 12'. M. semitendinosus. 
 
 13. M. semimembranosus. 
 
 14. Mm. gemelli. 
 
 15. M. quadratus femoris. 
 
 16. M. vastus externus. 
 
 17. M. gastrocnemius. 
 
 18. M. soleus. 
 
 19. M. peroneus or extensor digitalis lateralis. 
 
 20. M. extensor pedis or extensor digitalis longus. 
 
 21. M. fle.xor peiiforans. 
 
 22. One of the anterior gluteal nerves. 
 
 23. Gluteal nerve to M. biceps femoris. 
 
 24. Sacro-sciatic ligament. 
 
 25. 25'. Posterior ventral gluteal nerve. 
 
 26. N. ischiadicus. 
 
 27. Nerve to the Mm. gemelli, obturator internus and quadratus femoris. 
 
 28. Nerve fasciculus to the Mm. biceps femoris, semitendinosus and semimembranosus. 
 
 29. N. peronaeus communis. 
 
 30. 30'. N. peroneal cutaneous. 
 
 31. Small filament to the femoro-tibial joint. 
 
 32. N. peronaeus superficiaUs. 
 32'. Nerve branch to M. peroneus. 
 
 32". Superficial or subcutaneous branch of N. peronaeus superficialis. 
 
 33. N. peronaeus profimdus. 
 
 34. N. tibialis. 
 
 35. N. saphenus extemus. 
 
 36. Nerve filament to M. soleus. 
 
ir 
 
 10 
 
 < 30 
 
 ^ 
 
PLATE V 
 MEDIAL VIEW. 
 
 1-6. Lumbar vertebrae. 
 I '-5'. Sacral vertebrae. 
 I "-6". Coccygeal vertebrae. 
 
 7. Pelvic symphysis. 
 
 8. 8'. M. psoas parvus. 
 
 9. M. psoas magnus. 
 
 10. M. iliacus. 
 
 11. 11'. M. sartorius. 
 
 12. M. obliquus abdominis intcrnus. 
 
 13. M. transversus abdominis. 
 
 14. M. rectus femoris. 
 
 15. M. vastus intemus. 
 
 16. M. gracilis. 
 
 17. Portion of prepubian tendon. 
 18,18'. M. obturator intcrnus. 
 
 19. M. sacro-coccygeus. 
 
 20, 20'. M. compressor coccygcus. 
 21,21'. M. retractor ani. 
 
 22. M. retractor penis. 
 
 23. M. recto-coccygeus. 
 
 24. M. sphincter ani externus. 
 
 25. M. sphincter ani intemus. 
 
 26. Sacro-sciatic ligament. 
 
 27. Aorta. 
 
 28. A. mesenterica posterior. 
 39. A. circumflexa iliaca. 
 
 l.So. A. iliaca (of right side). 
 30 ' Cut end of left A. iliaca. 
 
 31. Truncus pudendo-epigastricus (prepubic artery). 
 
 32. A. femoris anterior. 
 
 33. A. femoralis. 
 
 34. A. iliaca interna. 
 
 35. A. sacrahs lateralis. 
 
 36. A. glutea anterior. 
 
 37. A. pudenda interna. 
 
 38. A. obturatoria. 
 
 39. A. umbilicalis. 
 
 40. V. obturatoria. 
 
 41. V. femoralis. 
 
 42. Large vein in subpubic groove. 
 
 43. V. pudenda externa. 
 
 XVIII. Last thoracic nerve. I-VI. Lumbar nerves. 
 I'-IV. Sacral nerves. 
 
 44. Posterior mesenteric ganglion of the sympathetic ner\'e (just below 44). 
 
 45. Sympathetic nerve trunk. 
 
 46. 46'. N. femoralis. 
 
 47. N. saphenus intemus. 
 
 48. Branch of N. saphenus intemus to M. sartorius. 
 
 49. N. obturatorius. 
 
 50. Small nerve to the M. obturator intemus. 
 
 51. Pelvic plexus. 
 
 52. Anterior gluteal nerve to the Mm. tensor fasciae latae and gluteus superficialis. 
 
 53. Nerve to the M. gluteus profundus. 
 
 54. N. ischiadicus. 
 
 55. Posterior ventral gluteal nerve. 
 
 56. Posterior dorsal gluteal nerve. 
 
 57. 57'- N. pudendus. 
 
 57". N. dorsalis penis (of the left side) a continuation of the N. pudendus. 
 
 58. Small nerves to the pelvic plexus. 
 
 59. Branch of N. haemorrhoidalis to the M. retractor ani. 
 
 60. N. haemorrhoidalis. 
 
 61. Branch of N. haemorrhoidalis to the M. compressor coccygeus. 
 
 62. Nerve branch to rectum. 
 
 63. Deep inguinal lymph gland. 
 
 64. External iliac lymph glands. 
 
 r 
 
PLATE VI 
 LATERAL VIEW OF PELVIC LIMB 
 
 1 . External small or third trochanter. 
 
 2. Lateral epicondyle of femur. 
 
 3. Os calsis. 
 
 4. Lateral rudimentary metatarsal. 
 4'. Principal metatarsal. 
 
 5. 5'. M. vastus extemus. 
 
 6. M. adductor magnus. 
 
 7. M. semimembranosus. 
 
 8. M. semitendinosus. 
 
 9. 10. M. biceps femoris (turned aside). 
 
 11. 11'. Lateral or external head of M. gastrocnemius (transected and the distal portion turned aside). 
 11". Medial or internal head of M. gastrocnemius. 
 
 12. M. flexor perforatus (a short section has been removed). 
 
 13. M. popliteus. 
 
 14. M. flexor digitalis longus. 
 
 15. M. soleus. 
 
 16. M. flexor perforans. 
 
 17. M. peroneus or extensor digitalis lateralis. 
 
 18. M. tibialis anterior. 
 
 19. M. extensor pedis or extensor digitalis longus. 
 
 20. M. extensor brevis. 
 
 21. M. interosseus lateralis. 
 
 22. M. lumbricalis lateralis. 
 
 23. 23', 23". Tibial and metatarsal aponeurosis. 
 
 24. Suspensory or suprasesamoid ligament. 
 
 25. Ligament of ergot. 
 
 26. A. metatarsea dorsalis (lateralis). 
 
 27. A. digitalis lateralis. 
 
 28. V. digitalis lateralis. 
 
 29. N. tibialis. 
 
 30. N. peronaeus communis. 
 
 31. Small branch from N. peronaeus communis to N. saphenus extemus. 
 
 32. 32'. N. peronaeal cutaneous. 
 
 33. N. peronaeus superficiaUs. 
 
 33'. 33"- Muscular and cutaneous branches of N. peronaeus superficialis. 
 
 34. 34'. N. peronaeus profundus. 
 
 35. Branch of N. peronaeus profundus accompanying the A, metatarsal dorsalis (lateralis). 
 
 36. 36'. N. saphenus extemus. 
 
 37. N. plantaris lateralis. 
 
 38. Communicating branch for the N. plantaris medialis to the plantaris lateralis. 
 
 39. 40, 41. Anterior, middle and posterior branches of N. digitalis lateralis. 
 42. Portion of N. digitalis in the dorsal groove of third phalanx. 
 
PLATE VII 
 
 DIAGRAM OF THE LUMBO-SACRAL NERVE PLEXUS 
 
 1-6. Lumbar vertebrae. 
 
 I '-5'. Sacral vertebrae. 
 
 I "-6". Coccygeal vertebrae. 
 
 I-VI. Ventral branches of lumbar nerves. 
 
 I'-V. Ventral branches of sacral nerves. 
 
 I"-V". Ventral branches of coccygeal nerves. 
 
 7. Gangliated nerve-trunk of the .sympathetic nerve. 
 
 8. Ramus commmiicans. 
 
 9. N. ilio-hypogastricus. 
 
 10. N. ilio-inguinalis. 
 
 11. N. spermaticus externus. 
 
 12. N. cutaneous femoris lateralis. 
 
 13. Branch to M. psoas parvus. 
 
 14. N. femoralis. 
 
 15. Branch to M. iliacus. 
 
 16. N. obturatorius. 
 17-20. Nn. glutei anterior. 
 
 21. N. ischiadicus. 
 
 22. Posterior ventral gluteal nerve. 
 
 23. Posterior dorsal gluteal nerve. 
 
 24. N. pudendus. 
 
 25. Small nerves to the pelvic plexus. 
 
 26. Ner\'e to the M. retractor ani. 
 
 27. N. haemorrhoidalis. 
 
 28. 29. Fourth and fifth sacral nerves. 
 
 30. First coccygeal nerve. 
 
 31. Nerve trunk formed by branches of the coccygeal nerves. 
 32-36. Coccygeal nerves. 
 
^8 
 
 W 
 
 V^ 
 
 ^Vl 
 
 .13 
 
 '10 
 
 n 
 
 i|2 
 
 fl4 
 
 -13 
 
 19 
 
 >23 
 
 ^2 6 24 
 
 ^2^ -,o^27 
 
 28 
 
 ;3o 
 
 -31 
 
 '!^ 
 
 -32 
 
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