"700 



METACARPUS. 



All the bones of the raetacarpal series have a convexity 

 on their dorsal surface and a concavity on their palmar. 



FJG. 220. The metacarpal bone of the thumh 



is the strongest and shortest of the 

 whole; its slightly concave carpal 

 end articulates with the trapezium ; 

 its slightly concave phalangeal end 

 with the first hone of the thumh. 

 On either side of the phalangeal 

 extremity a tubercle is seen on 

 which is placed a sesamoid bone. 



The second metacarpal bone, or 

 that of the forefinger, is distin- 

 guished from the rest by its greater 

 length ; it articulates at its carpal 

 end by a deep concavity in the 

 middle with the trapezoides. There 

 is a smooth articular face for the trapezium on the one side 

 and the magnum on the other. The base,, on its palmar 

 surface, presents a rough portion for the insertion of the 

 flexor carpi radialis, and a like roughness on the dorsal 

 base for the insertion of the extensor carpi radialis lon- 

 gior. The palmar portion of the shaft is divided by a 

 longitudinal ridge into two surfaces for the interosseous 

 muscles. 



The third metacarpal bone is the next in size, but rather 

 shorter than the last. Its carpal extremity is triangular, 

 and articulates with the os magnum ; it has on its radial 

 side a tubercle for the insertion of the extensor carpi 

 radialis brevior. On either side of the base are seen articu- 

 lar faces for the second and fourth metacarpal bones. 



The fourth metacarpal bone is smaller and shorter than 

 the third. Its carpal extremity articulates with the unci- 



FIG. 220 represents the Metacarpus and Phalanges, a Scaphoides. b Lunare. 

 c Cuneiforme. cJPisiforme. e Trapezium. /Groove for tendon of flexor carpi 

 radialis g Trapezoides. /iOs-magnum. i Unciforme. jj Metacarpal bones. 

 k k Phalanges first row. 1 1 Phalanges second row. m m Phalanges third 

 row. n First phalanx of the thumb, o Last phalanx of the thumb. 



