THOEACIC LIMBS 



615 



471). 



The dorsal surface (Fig. 484) presents the form of a truncated 

 triangle, whereof the base is below and the apex is above. The outer 

 or radial border is almost vertical, and is slightly 

 emarginate. The ulnar border is straight, and 

 runs downward and to the ulnar side for most 

 of its extent, but before reaching the distal border 

 bends sharply to the radial side. The distal 

 border is transverse ; the proximal border runs 

 obliquely downward and to the radial side. The 

 dorsal surface is gently convex from side to side 

 and somewhat excavated above ; it is everywhere 

 slightly roughened for the attachment of liga- 

 ments. 



The distal surface (Fig. 480) is pear-shaped, 

 with the wide portion at the dorsal side and the 

 narrow portion at the palmar side. It is strongly 

 concave from before backward, and divided by a 

 longitudinal low line into two nearly equal artic- 

 ular surfaces, which are slightly concave trans- 

 versely and articulate with the Bases of the fourth 

 and fifth metacarpals. Its radial and dorsal borders are gently arcuate ; 

 its ulnar border is emarginate. 



FIG. 480. 

 Dorsal Side. 



POSITION OF UNCIFORM. 



With Fourth Mdacarpal. 



Radial Side. 



With Fifth Mdacarpal. 



Ulnar Side. 



Palmar Side. 



LEFT UNCIFORM, DISTAL SURFACE. 



The palmar surface is rough and irregular for the attachment of 

 ligaments. It is narrower than high, and is divided by a transverse 

 groove into two nearly equal prominences. 



The radial surface (Fig. 481) is almost square, but higher at the 

 dorsal end than at the palmar end, and longer at the distal margin 

 than at the proximal margin. Its proximal border is sinuate, arcuate at 

 the dorsal end and emarginate behind. The dorsal and distal borders 



