THE ANTERIOR EXTREMITIES. 83 



■\Yard (see Skel.) . Upon its length and obliquity the ease and 

 elasticity of the motion of the animal greatly depend : never- 

 theless, when these properties are very considerable, it must 

 require a corresponding effort in the tendinous and liga- 

 mentous parts to preserve it in its situation ; hence very long- 

 jointed horses are weaker, and more liable to become strained 

 than others. Its superior surface receives the greater part 

 of the inferior surface of the cannon : posteriorly it articulates 

 with the sessamoids ; and interiorly with the small pastern. 

 The body of the bone is much smaller than its extremities. 



The sessainoids {Skel. X) are two small w^edge-shaped 

 bones, situated at the point of the fetlock, exactly behind 

 the inferior head of the cannon ; and also articulating wdth 

 the back of the upper part of the great pastern bone ; to 

 both of which they unite very closely, fitting into depres- 

 sions suited to their prominences. With the cannon the 

 connexion is very close ; by means of a ligament, through 

 which, and by the nature of their situation, they support a 

 portion of the stress and weight of the body imposed upon 

 these bones. They are placed side by side ; with their 

 thinner portion pointed upwards, and their thicker and 

 more obtuse part downward ; by which latter they are firmly 

 attached to the pastern bone by strong fibres, as well as by 

 the suspensory ligament. Between and behind them a 

 hollow is left, through which the flexor tendons slide with 

 freedom and partial security. 



The use of these bones is more important than, from 

 their size, a casual observer might be disposed to think. 

 Their strongest attachment is to the great pastern bone ; 

 their w^eakest to the suspensory ligament. But then they 

 are very closely united to the cannon bone, and the liga- 

 ment before named ; pressure from behind, from the flexor 

 tendons, also serves to force them into, and to keep them 

 in their right places. They can move downward, because 

 their connexions admit of motion in that direction ; but only 

 to a certain distance ; because the connexion to the sus- 

 pensory ligament prevents it ; and because the flexor tendons 

 pressing on them behind hinder them from descending very 

 low. The force which displaces them, or causes them to 

 descend, is the cannon bone ; when in progression it is 

 thrown backward. In horses, with very oblique pasterns, 



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