86 CONFORMATION AND ITS DEFECTS 



providing for a large range of action, and also for the accommodation of 

 muscles proportionate in extent. Any shortcoming in these respects 

 diminishes the horse's stride, in which case the speed can only l)e kept up 

 by multiplying his movements, which,- of course, tends to physical exhaus- 

 tion. With a long leg velocity of the gait is best served by a short canon. 



As in the case of the thigh, the direction of the leg should neither be 

 too straight nor too much inclined. A leg that is too straight brings the 

 limb unduly forward, and shortens the step by limiting the power of exten- 

 sion, while one that is too much inclined throws the leg too for back and 

 limits the power of flexion. 



It is important that the superior part of this region should be well 

 furnished witli muscle brought down from a well-developed thigh and 

 buttock. The lower part or " gaskin " should be wide, the hamstring 

 thick and bold, and well set away from the bone (tibia) by connection with 

 a long calcaneum or point of the hock. The longer this point is, the greater 

 will be the length of the lever arm, and the more power will the muscles 

 exercise in propelling the body forward by straightening the hock. 



HOCK 



This is the most complex, as it is also the most important, joint 

 concerned in the mechanism of locomotion. It is here that the strain 

 in the eSbrts of propulsion chiefly falls, and the joint at which the con- 

 cussion thereby developed is for the most part broken and dispersed. 



We may venture the statement that no joint in the body of the 

 horse presents such a variety of natural conformation in difterent indi- 

 viduals as the one under consideration, and none calls for such careful 

 scrutiny and analysis of detail both as to conformation and soundness. 



Two sets of bones enter into the construction of the hock-joint, each 

 having a purpose of its own. One group of four small bones (1, 2, 3, 4 

 in Fig. 67), arranged in two rows and resting on the head of the canon, 

 are united together and to adjacent bones by short, powerful ligaments, 

 and so close is the union that the movement of one bone upon the other 

 is reduced to a simple gliding action of the most limited extent. This 

 movement, slight though it be, is of the first importance in breaking the 

 jar communicated to the joint in the act of progression. 



The second division comprises two large bones — the astragalus and 

 the calcaneus. The former presents in front two smooth, prominent 

 ridges and a deep, intervening furrow, after the fashion of a jjulley, 

 which, when articulated with a corresponding formation on the lower 

 extremity of the tibia or leg bone, form a joint whose action in the 



