154 



THE STRUCTURE OF THE HORSE 



os pedis. The joint between the metacarpal and the 

 first phalanx is the ' fetlock,' that between the first and 

 second phalanges the i pastern,' and that between the 

 second and third phalanges the c coffin-joint.' 



There are several other small bones in the horse's 

 foot which must be mentioned, and which belong to the 

 group called c sesamoids,' bones developed in tendons 

 where they play over joints. In the human hand there 

 is a pair of these over the palmar surface of the meta- 

 carpophalangeal joint of the thumb, but none are deve- 

 loped in the other digits. In the horse there are three, 

 all also on the palmar surface (or behind in the natural 

 position) ; a pair of nodular form placed side by side 

 over the metacarpophalangeal Articulation (fig. 6, s), 

 and a single large, transversely extended one (fig. 6, s 1 ), 

 called the s navicular ' bone, behind the joint formed 

 between the second and third phalanges. 



In standing at rest in the natural position the fore- 

 arm and the metacarpus are nearly upright, and the 

 three bones of the digit or finger form a nearly straight 

 line with them, but inclining forwards at the lower end. 

 The third, or ungual phalanx, alone rests, through the 

 intermedium of the hoof, upon the ground, and receives 

 the whole of the weight of one-quarter of the animal's 

 body. 



The main peculiarities of the skeleton of the fore 

 limb of the horse are these : the absence of clavicle, the 



