612 MAMMALIAN ANATOMY 



lunar ; (2) the rounded convex margin of the head, which fits into 

 the deep oblique groove on the under surface of the scapho-lunar ; and 

 (3) the ulno-palmar triangle, which is rough and gives attachment to 

 ligaments. The radial and ulnar borders of this surface are nearly 



FIG. 475. 



Palmar Side. 



Radial Side. /WL^ Wit ^? h ' Ulnar Side 



With Second Metacarpal. 

 % With Trdpezoid. 



Dorsal Side. 



LEFT OS MAGNUM, PROXIMAL SURFACE. 



parallel, and at right angles with the dorsal border. The palmar 

 border is obliquely truncate, so that the radio-palmar angle appears 

 as though produced. 



The dorsal surface (Fig. 460) extends across the bone, but is only 

 one-half as high as it is wide. At its ulnar side it passes upward into 

 the dorsal edge of the head. Its radial end is pointed and somewhat 

 higher than the rest of the surface. The lower part on the body is 

 rough, for ligamentous attachment. The part on the head is smooth, 

 covered with cartilage, and articulates with the scapho-lunar. 



FIG. 476. 

 Proximal Side. 



With Scapho-lunar. 



With Trapezoid. 



Palmar Side. rft^Pfll Dorsal Side. 



With Second Metacarpal. With Third Metacarpal. 



Distal Side. 



LEFT OS MAGNUM, RADIAL SURFACE. 



The radial surface is bounded above by the arched border of 

 the head, dorsally by a small vertical border, behind by the arcuate 

 palmar border, and below by the straight or slightly emarginate distal 

 border. The portion which belongs to the body appears as a process 



