MUSCLES OF THE ANTEBIOB LIMBS. 271 



digits, as the single perforatus tendon does in the Horse, except that they receive from 

 the suspensory hgament a fibrous band analogous to that wljioh, in Sohpeds soes to 

 the perforans tendon. This band (fig. 123, 13) concurs in the formation of the annular 

 ligament through which the latter tendon passes. 



In the Oa; the terminal tendon of the perforans does not receive any carpal band • 

 this goes to the perforatus. Above the fetlock, it divides into two branches, one for each 

 ru° .V, .,",', ''^'^'^ traversing the perforatus, terminates behind the inferior face of 

 the third phalanx. There it is blended with the plantar cushion, 

 the inferior interdigital ligament, and a fibrous fascia already 

 noticed in the description of that ligament. This layer arises 

 from the aponeurosis covering the flexor tendons in the meta- 

 carpal region ; it descends on the heels, behind and outside the 

 digits, remains united to that of the other digit by an inter- 

 mediate fibrous fascia, and is attached to the enveloping sheaths 

 of the flexor tendons, as well as to the superior interdigital liga- 

 ment. Each terminates inferiorly, in becoming united to the 

 proper extensor of the digit, the plantar cusliion, the inferior 

 digital ligament, and the deep flexor of the phalanges. 



There is not, properly speaking, h, phalangeal reinforcing 

 sheath ; though we may consider as such the superior fasciculi 

 of the inferior interdigital ligament (fig. \2i. 6). 



Pig. — 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, two muscles 

 are found analogous to those described as existing in Euminants. 

 The external, or common extensor of the digits, is easily divided 

 into several fasciculi, and is terminated by four tendinous branches 

 which reach the pyramidal eminence of the third phalanx of the 

 four digits. The tendon of the small external digit often gives 

 oif athin bifid ramification, destined to supplement the tendons of 

 the two large digits. The internal muscle, or proper extensor of 

 the two internal digits, possesses a bifurcated tendon ; each branch 

 goes to the excentric side of the third phalanx of the digit it is 

 charged to move. 



With regard to the muscles of the posterior antibrachial 

 region, it is remarked : 1, That the anterior branch of the ter- 

 minal tendon of the external flexor of the metacarpus passes to 

 the head of the outer metacarpal bone ; 2, That the internal flexor 

 terminates on the metacarpal of the great external digit ; 3, 

 That the perforatus is formed by two muscular bodies, each 

 terminated by a tendon inserted, inferiorly, into the second pha- 

 lanx of one of the great digits. 4, That the perforans is divided 

 into four terminal branches which arrive at the large phalanx of 

 the digits. 



Caenivoba. — In the Dog and Oat, the anterior extensor of the 

 metacarpus divides, at its lower extremity, into two branches, 

 which resemble those of the two external radial muscles of Man : 

 one is inserted into the metacarpus of the index, the other into 

 the metacarpus of the medius (fig. 125, A, 5, 6, 7). 



The oblique extensor passes to the metacarpus of the thumb; 

 it furnishes, besides, a small particular branch that glides, by 

 means of a sesamoid, over the third bone of the inferior row of 

 the carpus, and is blended with the posterior ligament of the 

 carpus (fig. 125, A, 8; B, 4; D, 8) ; it separates the thumb fiom the other digits, hut we 

 think it scarcely adapted for the function of extensor. 



The anterior extensor of the phalanges of solipeds is replaced by a single muscle, the 

 common extensor of the digits, terminated by a quadrifurcated tendon, whose branches 

 are distributed to the four great digits ^fig. 125, a, 9, 9'). 



The tendon of the lateral extensor is divided into three branches, which are inserted 

 on the anterior face of the three outer digits, and are blended with the tendons of the 

 common extensor, or with the fibrous bands furnished to these tendons by the inter- 

 osseous metacarpal muscles. 



The external flexor of the metacarpus comports itself as in the Pig, But the oblique 



TENDINOUS AND LIGA- 

 MENTOUS APPARA- 

 TUS OF THE POSTE- 

 EIOE FACE OF THE 

 DIGITAL EEGION IN 

 THE OX ; POSTEEIOE 

 LIMB. 



1, Perforatus tendon ; 

 2, 2, Its terminal 

 branches; 3, 3, Their 

 bifurcation ; 4, 4, 

 Perforans ; 6, 6, Su- 

 perior bands of the 

 inferior digital liga- 

 ment attached to the 

 first phalanx ; 7, In- 

 ferior interdigital 

 ligament ; 8, 8, Sus- 

 pensory ligament of 

 the fetlock. 



