The Skeleton 83 



cavity, and a larger, somewhat bilobed surface for 

 articulation with the radius and ulna. On its 

 ventral side, near the proximal end, is a very 

 prominent protuberance, the deltoid ridge. The 

 ulna (ii) is slightly heavier and longer than the 

 radius and forms the greater part of the elbow joint 

 and about half of the wrist joint. Its proximal 

 end is considerably larger than the distal, but has 

 no olecranon process. Its distal end articulates 

 with the ulnare and pisiform. The ulna as a whole 

 is slightly curved, while the radius is quite straight. 



The radius (r) consists of a cylindrical shaft with 

 enlargements of about equal size at the ends. 

 The proximal end articulates with the side of the 

 ulna and with the humerus; the distal end with 

 the radiale. 



The carpus consists of a proximal row of three 

 distinct bones and a distal row of smaller and less 

 fully ossified elements. Of the proximal row the 

 radiale (r') is much the largest bone. It is hour- 

 glass shaped, with the proximal end somewhat 

 larger than the distal. Proximally it articulates 

 mainly with the radius but also slightly with the 

 ulna and ulnare. Distally it articulates with the 

 centrale. The ulnare (ic'), the second bone in size 

 in the wrist, has about the same shape as the radiale 

 but is much smaller. Proximally it articulates 

 with the pisiform, radiale, and, apparently, with 

 the ulna; distally it is in contact with the fused 

 carpalia elements. The pisiform (p) is a small, 



