THE ANTERIOR LIMBS. 



Ill 



The carpal bones of the Hinny are hke those of the Ass, but those of the 

 Mule resemble the Horse. 



Fi^. 70. 



Differential Characters in the Carpal Bones of other Animals. 



A. Ox, Sheep, Goat. — In these animals the carpus is composed of only six bones — four 

 in the upper and two in the lower row, where the os magnum and trapezoid are fused together. 

 The pisiform bone is in shape as its name implies, has no groove, and has no relation with the 

 radius. The cuneiform bone articulates with the radius and ulna. The bones of the lower 

 row only articulate with the large metacarpal bone (Fig. 71). 



B. Camel. — Among tlie seven carpal bones of the Camel are seen : 

 a pisiform bone, having on its external face a large smooth groove ; a 

 lunar, flattened on each side, and deeply notched laterally ; an unciform 

 having a pyramidal prolongation behind ; an os magnum, smaller than 

 the latter ; and a trapezoid, little developed, and entirely removed to 

 the posterior part of the carpus. 



C. Pig. — The carpus of the Pig, like that of Man, contains eight 

 bones — four in each of the rows. The second bone of the upper row 

 articulates with the ulna, and to a very small extent with the radius. 

 In the bones of the lower row, it is observed that the first articulates 

 witli the two external metacarpals, the second with the great internal 

 metacarpal, the third with the preceding and the small internal meta- 

 carpal. The fourth, or trapezium, terminates inferiorly by a blunt 

 point, and has no relations with the metacarpal bones, because the thumb 

 is entirely undeveloped in this animal (Fig. 76). 



D. Dog, Cat. — In the Cat and Dog there are also eight bones. 

 Lesbre says, however, that the scaphoid and lunar are sometimes one 

 bone, and that often a lenticular bone is found in the upper row. The 

 cuneiform bone is very developed, and occupies all the external border of 

 the carpus, articulating with the ulna, first bone of the second row, and 

 the first metacarpal. 'J'he pisiform bone is elongated, prismatic, thick 

 at both ends, and has in front two contiguous articular facets— one for 

 articulation with tlie ulna, the other for union with the cuneiform bone. 

 The bones of the lower row diminish in size from the first to the fourth, 

 and articulate — the first, with the first and second metacarpals; the 

 second, with the metacarpal of the third digit; the third, with the 

 fourth digit ; and the fourth with the metacarpus of the thumb. 



E. Rabbit. — This animal possesses nine carpal bones; for it is 

 stated that between the two rows there is a piece which Blainville has 

 named the intermediate bone It really belongs to the upper row, and 

 represents the scaphoid. There are, therefore, five bones in the first 

 carpal row of the Rabbit, and in this respect the hand of this species 

 more nearly approaches the typical hand than that of the other domestic 

 animals (see the Hand in General). 



2. Metacarpal Bones (Figs. 67, 70). 



In Solipeds, the metacarpus is composed of three bones, 

 named the " metacarpals," standing parallel to each other. 

 These are the principal metacarpal and the two rudimentary 

 metacarpals — an external and internal. 



Principal Metacarpal Bone {psmetacarpi magnum').— 

 This is a long cylindrical bone, situated vertically between the 

 carpus and the digital region. 



Bodij. — The body is a little depressed before and behind, which permits it to 

 be described as having two faces and two borders. The anterior face is perfectly 

 smooth and rounded from side to side. The posterior face is flat, and exhibits : 

 1. Towards the upper third, the nutrient foramen of the bone. 2. On the sides, 



posterior view of 

 right metacarpus. 

 1, Head of large meta- 

 carpal bone for ar- 

 ticulation with the 

 trapezoi'i, magnum, 

 and unciform ; 2, 

 inner splint, rudi- 

 mentary, or small 

 metacarpal bone,for 

 articulation with 

 the trapezoid ; 4, 

 scabrous surface for 

 the attachment of 

 the suspensory liga- 

 ment ; 5, nutrinnt 

 foramen ; 6, median 

 ridge separating tne 

 two inferior con- 

 dyles. 



