36 STRUCTURE AND ECONOMY OF THE HORSE. 



The Elbow joint Is constructed on the principle of the hinge, 

 and is formed by the rounded pi'ominences of the humerus, 

 moving in corresponding depressions in the radius and uhia, the 

 bones of the arm ; and dislocation is effectually secured by a 

 strong ligament on each side, besides the capsular. 



The Knee joint is composed of no less than three articulations, 

 besides a smaller one behind the knee. 



The motion, however, is principally confined to the two upper 

 articulations, the bones of which sepai'ate considerably in front, 

 but are confined behind. These joints are each invested by a 

 loose capsular ligament, which permits the necessary extensive 

 motion of the joint, and are secured on each side by strong 

 lateral ligaments ; besides which there ai'c two annular bands, 

 one behind and the other in front, which serve to tie down and 

 confine the flexor tendons. 



Tha Fetlock joint is formed by the rounded extremity of the 

 cannon approximating Avith the concave surface afforded by the 

 large pastern below, and the two sesamoid bones behind. It has, 

 in addition to the capsular, no less than nine ligaments, seven of 

 Avhich are connected with the sesamoid bones, and thus serve to 

 keep them in their situation, in somewhat the same manner as 

 the masts of a vessel are secured by means of the rigging or stays. 

 The other two ligaments secure the joint firmly on either side. 



The Pastern joint possesses very little motion. It is formed 

 by the convex extremity of the large fitting into corresponding 

 concavities in the small pastern, and is secured by the capsular 

 and two ligaments on each side, and protected by tendons both 

 in front and behind. 



The Coffin joint possesses a greater degree of motion than the 

 pastern. It is formed by the upper concave surfaces of the 

 coffin and navicular bones receiving the convex extremity of 

 the small pastern. It is secured by a capsular and three pairs 

 of ligaments, connecting the coffin bone with the small pastern 

 and the side cartilages ; and four other ligaments, two of which 

 pass from the navicular to the small pastern, one joining the 

 navicular to the coffin bone, and another to the flexor sinew. 

 These ligaments, however, although numerous, are not strong, 

 as the joint is within the cavity of the hoof, and is thereby well 

 secui'ed from injury. 



Joints of the Hind Extremity. 



The Hip or Thigh joint is situated so deep-seated, and so well 

 protected by large muscles and tendonSj that it requires but very 

 few ligaments. It is, as before observed, a ball and socket joint, 

 the ball being formed by the upper part of the femur or thigh 

 bone, and the socket (which is considerably deeper than that of 



