TIIOBACIC LIMBS 613 



and presents two small articular facets: (1) the narrower and lower 

 facet on the front of the distal border, for the second metacarpal ; 

 (2) the upper square facet, for the trapezoid. On the portion of the 

 radial surface which is on the head a curved facet for the scapho-lunar 

 follows the superior border and joins the small facet on the upper or 

 proximal surface. Behind these facets is a rough surface, to which the 

 posterior part of the contiguous surface of the trapezoid is attached 

 by a strong ligament. Below this surface, near the distal border, is 

 a crescentic facet for the side of the base of the second metacarpal. It 

 is separated from the facet which is placed on the side of the process 

 for articulation with the second metacarpal by a small pit, into which 

 is inserted a ligament from that bone. A small rough space is left 

 free near the palmar border for the attachment of a ligament from 

 the base of the metacarpal. 



Almost the entire distal surface is occupied by a large oblong sur- 

 face, which is concave and articulates with the base of the third meta- 



FIG. 477. 

 Dorsal Side. 



With Second Metacarpal. 



With Third Metacarpal. 



. Vlnar Side. 



Hadial Side. jjfc .Jp, 



With Fourth Metacarpal. 



Palmar Side. 

 LEFT os MAGNUM, DISTAL SURFACE. 



carpal. At the palmo-ulnar angle is a triangular facet for a part of 

 the base of the fourth metacarpal. A groove separates the base of this 

 facet and th6 palmar end of the surface for the third metacarpal from 

 the palmar border of the distal surface proper, which is rough and 

 produced into a process at its radio-palmar angle. 



The triangular palmar surface is rough for ligamentous attachment, 

 and faces backward and to the ulnar side. 



The ulnar surface (Fig. 478) closely resembles the radial surface. 

 It differs in having the process-like projection of the body at the 

 palmar side. A narrow facet runs along the distal border from the 

 point of the projection, and when it reaches the dorsal border becomes 

 wider and turns up along the dorsal border and the anterior half of 



