STRUCTURE OF THE LIMBS OF THE HORSE 139 



inferior extremity of the shoulder bone, and terminate inferiorly 

 on the superior extremities of the principal and second or rudi- 

 mentary bone of the forearm. The posterior brachial muscles 

 are heavy and powerful. They are sometimes termed elbow 

 muscles, because they are attached to the point of the elbow. 



The region of the forearm is formed by two bones, the 

 radius and ulna. The radius is the principal bone and is classed 

 among the long bones. The ulna is an elongated flat bone. It is 

 attached to the external portion of the posterior face of the 

 radius and extends above the superior extremity of this bone 

 to form the point of the elbow. The radius articulates with the 

 upper row of knee bones. The muscles of this region, the anti- 

 brachial, are divided into two sub-regions, anterior and pos- 

 terior. They originate superiorly from the lower extremity 

 of the arm bone and the superior extremities of the bones of the 

 forearm, and terminate toward the lower extremity of the region 

 in tendons that become attached to the bones of the knee, cannon 

 and digit. 



The knee or carpal region is formed by seven short bones 

 that are arranged in two rows. They form a series of articu- 

 lations. These are the articulations between the two rows, be- 

 tween the bones of each row, and between the upper and lower 

 rows and the neighboring regions. jSTearly all the motion takes 

 place in the articulation between the upper row and the principal 

 bone of the forearm. 



The cannon or metacarpal region is formed by three bones. 

 These are the principal metacarpal or cannon bone, and the rudi- 

 mentary metacarpal or splint bones. The latter are attached 

 to the margins of the posterior face of the cannon bone. The 

 superior extremities of these bones articulate with the lower row 

 of carpal bones. The convex extremity of the cannon bone meets 

 shallow depressions in the superior extremity of the first digital 

 bone. This is termed the fetlock joint. The anterior and pos- 



