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Types and Market Classes of Ln^E Stock 



Anatomy of the Hind Leg 



The hind leg consists of the femur (or thigh bone) which is the 

 largest in the body and articulates below with the tibia and also with 

 the patella (or knee cap). The hock is composed of six bones which 

 may be divided into two sets, each having a purpose of its own. One 

 group of four small bones (tarsals), arranged in two rows and resting 

 on the head of the cannon, are united together and to adjacent bones 

 by short, powerful ligaments, and so close is the union that the move- 

 ment of one bone upon another is reduced to a simple gliding action 

 of very limited degree. Though slight, this movement is of much im- 

 portance in breaking the jar communicated to this joint when the 

 horse is in action. Above the small tarsal bones are two larger bones, 

 the astragalus and calcaneus, as shown in Fig. 150. 



Fig. 150. — Bones of the hock. A, Tibia; B, calcaneus; C, astragalus; D, 

 tarsals; E, cannon bone; F, splint bone. 



To the calcaneus is attached the strong tendon known as the 

 "tendon of Achilles." By means of it the muscles above exert a power- 

 ful pull upon the hock joint, producing extension of the joint. This 

 is the principal means of the horse's propulsion. The knob-like end 

 of the calcaneus (to which the tendon attaches) forms the point of the 

 hock. In some instances the pull upon the hock has been great enough 

 to produce a fracture of this bone. 



Sometimes a diseased condition is brought about by the ossifica- 

 tion into one mass of some or all of the bones of the hock. Thia is 

 called a "bone spavin" and is a serious unsoundness because it destroys 

 the important gliding action of the tarsals, stiffens the joint, and often 

 causes lameness. 



The parts below the hock are similar in structure to those below 

 the knee. 



