THE FOEE-LIMB 297 



for articulation with the trochlea, and also 

 two small articular surfaces for the radius. 

 Behind the elbow-joint, the bone forms the 

 large, laterally compressed olecranon process. 

 Thfe distal end of the ulna is small, and articu- 

 lates with the carpus. 



The wrist. In the rabbit the wrist or carpus consists 

 of nine small bones, of which one, the pisiform, is 

 commonly regarded as a sesamoid bone or ossifica- 

 tion in the tendon of a muscle, but by some anato- 

 mists is considered to be a rudiment of a sixth digit. 

 The arrangement of the remaining eight can only 

 be understood by comparison with more primitive 

 types. 



The typical carpus consists of nine bones, arranged 

 in a proximal row of three, articulating with the 

 radius and ulna ; a distal row of five, each of which 

 supports one of the digits ; and a central bone wedged 

 in between the proximal and distal rows. In the 

 rabbit the arrangement is as follows. 



a. The proximal row of carpals consists o^ the three 

 typical bones. 



i. The radiale, or scaphoid, is placed on the ianer or 

 preaxial side, and articulates with the radius. 



ii. The intermedium, or semilunar, is the middle 

 bone of the three, and articulates with the 

 radius. 



iii. The ulnare, or cuneiform, is the outer or post- 

 axial bone of the proximal row, and articu- 

 lates with the ulna. 



1). The central bone. 



i. The centrale is a small bone, articulating with 

 the distal surfaces of the intermedium and 

 radiale, and appearing to belong to the distal 

 row of carpals. 



