164 THE STRUCTURE OF THE HORSE. 



spends to the hand proper, the hinder surface being 

 the palm, long and narrow in the horse, as it is short 

 and broad in man. As only one metacarpal bone is 

 fully developed, there is but one digit or finger, which, 

 as in man, has three bones (phalanges, jp 1 , j9", and p s , 

 Fig. 6), connected by hinge-joints, allowing only the 

 motions of bending or straightening backwards and 

 forwards. The first phalanx is somewhat elongated, 

 the next very short, and the last (the ungual phalanx) 

 very broad and of a pecidiar semilunar form. These 

 bones are in veterinary anatomy called respectively 

 the " large pastern " or os suffraginis, the " small pas- 

 tern" or os cor once, and the " coffin-bone' 7 or os pedis, 

 The joint between the metacarpal and the first pha- 

 lanx is the "fetlock," that between the first and sec- 

 ond phalanges the " pastern," and that between the 

 second and third phalanges the " coffin- joint." 



There are several other small bones in the horse's 

 foot which must be mentioned, and which belong to 

 the group called " sesamoids," bones developed in ten- 

 dons where they play over joints. In the human 

 hand there is a pair of these over the palmar surface 

 of the metacarpo-phalangeal joint of the thumb, but 

 none are developed in the other digits. In the horse 

 there are three, all also on the palmar surface (or be- 

 hind in the natural position) ; a pair of nodular form 

 placed .side by side over the metacarpo-phalangeal 



