334 



THE MUSCLES. 



radial is the largest. The tendons of the three divisions become united in the carpal sheath, 

 and the resulting tendon is easily divisible into two as far as the middle of the metacarpus; 

 there it bifurcates, each branch passing into the terminal bifurcation of the band which repre- 

 sents the perforatus and goes to be inserted into the third phalanx, where it is covered by a 

 small reinforcing sheath. 



B. Pig (Fig. 187). — In this animal, the anterior extensor tendon of the phalanges passes to the 

 superior extremity of the inner large metacarpal bone, and that of the oblique extensor to the small 

 internal metacarpal. 



Instead of the anterior extensor of the -phalanges, four muscles are found — 



1. The proper extensor of the great internal digit alongside the anterior extensor of the 



metacarpus ; its tendon terminates in an expansion on the outside of the great internal digit, 



after receiving, inwardly, a band from the corresponding interosseous muscle. It gives off, 



towards the middle of the metacarpus, a very thin branch which 



goes to the outside of the small internal digit. 



2. The proper extensor of the great external digit, the largest 

 of tlie four, terminates in the same manner as the preceding, on 

 the outside of the great external digit. 



3. The common extensor of the two internal digits, is con- 

 tinued by a tendon which bifurcates above the metacarpus, and 

 gives off a branch that reaches the pyramidal process of the small 

 phalanx of the internal digit, while the other branch — the most 

 important — passes into the space between the metacarpals of the 

 great digits, and bifurcates, in its turn, in front of the metacarpo- 

 phalangeal articulation, to terminate on the pyramidal process of 

 each of the great digits. 



4. The common extensor of the two external digits, much 

 smaller than the preceding, is in great part concealed beneath the 

 proper extensor of the great external digit. Its somewhat thin 

 tendon bifurcates in front of the metacarpus, to give a branch to 

 the small external digit, going to the pyramidal process ; and a 

 second branch that goes to the principal tendon of the preceding 

 muscle, from which it soon becomes detached to gain the small 

 phalanx of the great external digit. 



Lastly, there is in the Pig a representative of the proper 

 extensor of the thumb and index, but its tendon — the thickness 

 of a thread — is lost in that of the common extensor of the two 

 internal digits. 



There is also a round pronator along the anterior border of 

 the internal ligament of the elbow-joint, as well as a short supi- 

 nator. The latter, extremely thin, has no humeral insertion ; it is 

 thrown diagonally on the anterior and upper face of the radius. 



With regard to the tendon of the lateral extensor of the pha- 

 langes, or proper extensor of the external digit, this spreads out on 

 the outer face of that digit. 



With regard to the muscles of the posterior antibrachial region, 

 it is remarked that : 1. The anterior branch of the terminal tendon 

 of the external flexor of the metacarpus passes to the head of 

 the outer metacarpal bone. 2. The internal flexor terminates on 

 the metacarpal of the great external digit. 3. The perforatus ia 

 formed by two muscular bodies, each terminated by a tendon in- 

 serted, inferiorly, into the second phalanx of one of the great digits. 4. The perforans is 

 divided into four terminal branches, which arrive at the last phalanx of the great and small 

 digits. 



The external flexor of the metacarpus is almost transformed into a flat fibrous cord, extending 

 from the epitrochlea to the pisiform bone, and to the outer side of the carpus, where it expands. 

 The oblique flexor of the metacarpus is reduced to a thin muscular cord without an ulnar 

 insertion. 



The internal flexor of the metacarpus, the most developed of the three, is inserted below on 

 the metacarpal of the small internal digit. 



The muscular portion of the perforatus throws off a fasciculus to the perforans, and bifurcates 

 inferiorly ; the superficial branch passes out of the carpal slieath, and terminates by a tendon, 

 in the ordinary manner, on the second phalanx of the great external digit ; the deep branch 



TENDINOUS AND LIGAMEN- 

 TOUS APPARATUS OF THE 

 POSTERIOR FACE OF THE 

 DIGITAL REGION IN THE 

 OX (POSTERIOR LIMB). 



1, Perforatus tendon ; 2, 2, 

 its terminal branches ; 

 3,' 3, their bifurcation ; 

 4, 4, perforans ; 6, 6, su- 

 perior bands of the in- 

 ferior digital ligament 

 attached to the first pha- 

 lanx ; 7, inferior inter- 

 digital ligament ; 8, 8, 

 suspensory ligament of 

 the fetlock. 



