198 



HEALTH AND DISEASE 



side, is a roughened prominence into which the tendon of its extensor 

 muscle is inserted. At the back jsart of the upper end there is a roughened 

 patch for the attachment of the suspensory and check ligaments. The 

 lower extremity is rounded from before to behind, and divided by a 

 prominent ridge into two nearly equal parts or condyles. The whole of 



this end is covered with cartilage, and 

 articulates with a corresponding surface 

 formed by the upper extremit}' of the os 

 suffraginis, or large pastern bone, and the 

 two small sesamoid bones behind. 



Os Suffraginis, Large Pastern, or 



First Phalanx (fig. 304).— The large pas- 

 tern is a short stout bone placed between 

 the small pastern below and the fetlock 

 joint above. Its superior extremity is 

 larger than the inferior, and presents two 

 shallow depressions separated by a groove, 

 into which the central ridge and two con- 



Fis:. 303. — Metacarpal Bones (Posterior 

 View) 



' Outer Small Metacarpal Bone. -Inner 

 Small Metacarpal Bone. ^ Lai'ge Metacar- 

 pal Bone. '' Nutritive Foramen. ^ Ar- 

 ticular Condyles. ^ Intervening Ridge. 



Fig. 30-1. — Os Suffraginis or Large Pastern 

 Bone 



dyles, already spoken of as existing on the lower end of the canon, are 

 fitted to form a joint of considerable extent of motion. The lower ex- 

 tremity is small, and divided by a superficial groove into two condyles. 

 Sesamoid Bones (lO, fig. 302). — These are two small floating bones 

 situated behind the inferior extremity of the canon. They are somewhat 

 triangular in form, with their bases directed downward, and are closely 

 united one to the other. In front they are covered with cartilage, and 

 articulate with the condyles of the canon bone, thus forming part of the 



