OCR Text |
Show 184 MR. F. J. BELL ON MOSCHUS MOSCHIFERUS. [Feb. 1, In the Pig the digits are all supplied from the common extensor, by its division into four branches ; while the extensor dig. interni, further, is inserted into both the internal digits, and the fifth possesses a proper extensor dig. minimi. Now in Moschus each digit is provided with an extensor; but the so-called common extensor, as in Cervus, sends out only two branches, and these for the median digits, into whose third phalanges they are inserted. The internal extensor is inserted into the first phalanx of the third digit, on its anterior face, and the third phalanx of the second, on its inner face. The external extensor is inserted into the outer sides of the second phalanx of the fourth, and of the third phalanx of the fifth digit. A small extensor dig. minimi is also present, and is inserted into its second phalanx, after crossing the extensor of the fourth digit, in the last or distal third of the metacarpus, as in C. virginianus, as already described, though not as in the Sheep, where this muscle is-absent. In Tragulus the common extensor is inserted only into the median digits ; but in Hyomoschus, as Chatin says, the arrangement is Porcine ; that is, the common extensor is inserted into all four digits. As in the Sheep and Pig, the extensors of the phalanges arise on the outer side of the radius, and from the external tuberosity of the humerus; their tendons passing together along a deep groove on the outer face of the distal end of the radius, in a strong fibrous sheath, are directed, according to their destination, more or less inwardly along the anterior face of the metacarpus. Separated from these, however, is the tendon of the internal extensor, the fleshy body of which lies on the flattened outer face of the ulna, while the tendon itself, more deep, has a separate carpal sheath ; when it has passed through this, it widens, but does not bifurcate till it approaches the distal end of the metacarpus. j3. Posterior face (1) Perforal (2) Perforans ( U C A U , S U1 lI,e U1§ Perforatus ] a c ,, ,. >o< n^e..... r flexors of the digits. The short flexor of the fifth digit, which is found in the Pig and Hyomoschus, is absent. In no known Ungulate does the perforatus send tendons to the lateral digits, but only to the second phalanx of each median digit. In all members of the group its fleshy portion consists of two masses of muscle, arising beneath the flexor metacarpi obliquus, from the internal condyle of the humerus; in the Sheep these two tendons, arising from the two muscular masses, one from each, unite in the metacarpal region, and, more distally, bifurcation occurs ; in Cervus virginianus, the two tendons remain separate, as also in the Pig and Hyomoschus. In Moschus, however, there is a certain union of the tendons, by means of a fine slip of tendon running from the inner to the outer branch, in the metacarpal region. The perforans, as in the Horse, Sheep, and Pig, consists of three muscular portions, called by Chauveauepitrochlean, ulnar, and radial, |