110 



THE SKELETON OF THE HORSE 



Development. — The fibular tarsal bone has two centers of ossification, one for 

 the main mass and the other for the tuber calcis; the latter fuses with the rest of the 

 bone at about three years of age. The first and second tarsals have separate cen- 

 ters, but fusion usually occurs before birth. Each of the other bones ossifies from 

 a single center. 



Tuberosity - 



Ridges for 

 attacJwient 

 of middle in- 

 ferior sesa- 

 moid ligament 



Imprint for 

 tendon of _ 

 superficial 

 flexor 

 Condyle ■' 

 Transverse 

 prominence ~ ~ 



Condyle 



Proximal 

 border^^ 



Flexor 

 surface ~~ 



Wing 



Volar ; ,,- 

 groove^^-- 

 Volar 

 foramen-- 

 Semilu- _,- 

 nar crest ' 



Flexor 

 surface 



Fig. 



, Proximal 

 sesamoids 



.r/f- 



Phalanx I 



Phalanx II 



Third 

 sesamoid 

 or navic- 

 ular bone 



Proximal 

 sesamoids 



Phalanx I — 



Phalanx II 



Third sesa- 

 moid or na- 

 vicular bone 



' Phalanx III 



86. — Digital Bones of Fore Limb of Horse, 

 Volar Aspect. 



Foramen 

 I Notch 



Phalanx Iliy 



Fig. 87. — Digital Bones of Hind Limb of Horse^ 

 Volar Aspect. 



THE METATARSUS 



The metatarsal bones (Ossa metatarsalia), three in number, have the same 

 general arrangement as the metacarpal bones, but present some important differ- 

 ences. Their direction is slightly oblique, downward and a little forward 



The large or third metatarsal bone is about one-sixth longer than the corre- 

 sponding metacarpal ; in an animal of medium size the difference is about two inches. 

 The shaft is more cylindrical, and is almost circular on cross-section, except in its 

 lower part. At the upper part of its external surface there is a groove, which is 

 directed obliquely downward and backward, and is continued by the furrow formed 

 by the apposition of the external metatarsal bone; it indicates the course of the 

 great metatarsal artery. A faint impression in a similar place on the inner side 



