BONES OF THE THORACIC LIMB 



179 



osseous space, and is marked in its upper part by the nutrient foramen. From this 

 space a vascular furrow descends to the distal part of the shaft, where there is often 

 a distal mterosseous space for the passage of vessels. The medial surface is exten- 

 sive, concave, and smooth. The lateral surface is slightly convex, and its proximal 

 part IS marked by an oblique rough line or ridge. The proximal extremity is 

 large and is bent medially somewhat; its length is more than one-third of that of 

 the entire bone. The distal extremity is relativeh' small; it articulates with the 

 ulnar and accessory carpal bones, and is notched in front to accommodate the ridge 



Mc. 2 



Mc. 2 



Fig. 189. — Skeleton of Distal Part of Left Thor- 

 acic Limb of Pig; Dorsal View. 

 R, Distal end of radius; U, distal end (styloid proc- 

 ess) of ulna; C. v., radial carpal; C. i., intermediate 

 carpal; C. u., ulnar carpal; C. 2, C. 3, C. 4. second, 

 third, and fourth carpal bones; Mc. 2-5, metacarpal 

 bones; Ph.l, Ph,2, Ph. 3, first, second, and tliird pha- 



W 



Fig. 190. — Skeleton of Distal Part op Left 

 Thoracic Limb of Pig; Volar View. 

 R, Distal end of radius ; U, distal end (styloid proc- 

 ess) of ulna; C. r., C. t., C. u., C. a., radial, intermedi- 

 ate, ulnar, and accessory carpal bones; C. 1—4, first to 

 fourth carpal bones; Mc. 3-5, metacarpal bones; Ph. 1, 

 Ph. 2, Ph. 3, first, second, and third phalanges; S, prox- 

 imal, and S', distal sesamoid bones. 



on the radius. The bone contains a considerable medullary canal, and is con- 

 solidated at three to three and a half years. 



The carpus comprises eight bones, four in each row. The bones of the prox- 

 imal row resemble those of the ox, with the exception of the accessory, which is more 

 like that of the horse, but has no lateral groove. The first carpal is small, elon- 

 gated from before backward, rounded, and articulates in front with the second carpal. 

 The latter is high and narrow, and articulates with the second and third metacarpal 

 bones distally. The third carpal articulates with the radial and intermediate 

 above, the third metacarpal bone below. The fourth is the largest bone of the row; 

 it articulates with the intermediate and ulnar above, the fourth and fifth meta- 

 carpals below, and bears a tuberosity on its volar aspect. 



