114 



TEE BONES. 



middle two are always longer than the two lateral. The smallest belongs to the fifth digit, or 

 thumb, and is terminated interiorly by a trochlea. 



D. Pig. — The four metacarpals of the Pig articulate with each other, as in the Carnivora. 

 The second and third are larger tliau the first and fourth. The fifth metacarpal is not 

 developed (Fig. 76). 



3. Bones of the Phalangeal or Digital Eegion (Figs. 72, 73). 



Solipeds have apparently only one digit, supported by the principal metacarpal 

 bone, and composed of three pieces placed end to end, one upon another. The 

 first comprises three bones — a principal, the Jirst phalanx — and two complemen- 



Fig. 72. 



Fig. 73. 



LATERAL VIEW OF THE DIGITAL 

 REGION (OUTSIDE OF RIGHT LIMB). 



1, Large metacarpal bone ; 2, .3. outer and 

 inner sesamoids; 4, first, ])roximal, os suf- 

 fraginis, or metacarpal phalanx ; 5, its 

 posterior surface ; 6, tuberosity for liga- 

 mentous insertion ; 7, inner condyle of 

 ditto ; 8, eminences on second phalanx for 

 attachment of lateral ligament; 9, smooth 

 surface for passage of deep flexor tendon 

 on second phalanx ; 10, median or second 

 phalanx, os corona, or small pastern bone ; 

 11, navicular bone; 12, third phalanx, 

 pedal, or coffin bone ; 13, its basilar process. 



POSTERIOR VIEW OF THE DIGITAL REGION. 



1, Large metacarpal bone ; 2, 3, outer and 

 inner splint bones ; 4, b, sesamoid bones ; 

 6, suffragiuis ; 7, 8, tuberosities for inser- 

 tion of crucial ligaments ; 9, triangular 

 space for insertion uf short sesamoid liga- 

 ment ; 10, anterior face of suffraginis ; 

 11, 12, tuberosities for ligamentous inser- 

 tion ; 13, articular depression separating 

 condyles; 14, 15, second phalanx; 16, 

 scabrous surface for ligamentous attach- 

 ment; 17, smooth surface for gliding of 

 deep flexor tendon ; 1 8. navicular bone ; 

 19. }iedal bone; 20, basilar process; 21, 

 plantar foramen. 



tary ones, the sesamoids. The second is formed by the second phalanx, and the 

 last, which terminates the limb, is constituted by the third phalanx, and an 

 accessory bone which has received the name of the small sesamoid {navicular 

 bone). 



First (proximal) or Metacarpal Phalanx (Large Pastern Bone, or 

 Os Suffraginis). — The first phalanx (Figs. 72, 73), the smallest of all the 

 long bones, is situated in an oblique direction from above downwards, and 

 behind to before, between the principal metacarpal and the second phalanx. 



