OSTEOLOGY OF THE HORSE. 73 



The internal, implanted above, into a depression in the side of 

 the internal condyle of the humerus, and below, where it becomes 

 bifid, into the border of the inner articular cavity of the radial 

 portion of the bone, and also into the body of the bone, about 

 three inches below the first insertion. The external, shorter and 

 stronger, runs from a similar depression on the external condyle 

 to a tubercle on the upper and outer part of the radial bone. — In 

 the young subject, the ulnar portion of the arm-bone is united 

 to the radial by a fibro-cartilage ; but this gradually undergoes 

 conversion into bone as the adult period approaches. 



Knee-joint. — This includes four distinct articulations : one 

 between the arm-bone and the upper row of the carpal bones ; 

 a second, between the upper and under rows of the carpal bones 

 themselves ; a third, between the under row and the three meta- 

 carpal bones ; a fourth, situated posteriorly, between the trape- 

 zium and the cuneiform bone. They have ail their own proper 

 capsular membranes, which are attached around the borders of 

 their cartilaginous surfaces, and consequently have no communi- 

 cation one with another. The knee-joint altogether is further 

 maintained by — 1st, The lateral ligaments : the e.t7e;'»a/, passing 

 on the outside from a tubercle on the arm-bone to the head of the 

 external metacarpal bone ; the internal, divided into two portions 

 proceeding together from a similar tubercle on the inner side of 

 the arm-bone, the longer to be fixed to the head of the internal 

 splint-bone, the shorter to the inner and fore part of the large 

 metacarpal bone. Besides these, there are two annular liga- 

 ments, one, the anterior, traversing the front of the knee, being- 

 attached on the sides, and confining down the extensor tendons ; 

 the other, the posterior, passing across, behind, from the scaphoid 

 and cuneiform bones to the trapezium, inclosing the flexor tendons. 



The fetlock-joint is composed by the apposition of the in- 

 ferior condyloid extremity of the cannon bone to the upper bi- 

 concave surface of the pastern bone, and by the addition, poste- 

 riorly, of the sesamoid bones, which are also fitted to the con- 

 dyles of the cannon. Its binding parts are— 1st, The capsular 

 membrane, which is infixed into the bone around the borders of 

 the cartilaginous surfaces, and in front is inseparably united with 

 the extensor tendon. 2d, The internal lateral ligaments : the long 

 one passing from a little projection on the side of the large meta- 

 carpal bone to the pastern ; the short one, passing underneath the 

 former, from a depression immediately below the eminence to the 

 pastern, behind the insertion of the long ligament. 3d, The se- 

 ven SESAMOID ligaments: — a. The suspensory ligament^ (so 



* Bourgelat has regarded it as a tendon — " le tendon suspenseur dii boulet;" 

 Girard as a muscle — " M. Tarso-phalangien." 



