First metacarpal bone
|Bone: First metacarpal bone|
|The first metacarpal (Left)|
|Bones of the left hand. Dorsal surface.|
|Latin||ossa metacarpalia I|
|Gray's||subject #55 228|
The first metacarpal bone (metacarpal bone of the thumb) which connects to the thumb is shorter and stouter than the others, diverges to a greater degree from the carpus, and its volar surface is directed toward the palm.
The body is flattened and broad on its dorsal surface, and does not present the ridge which is found on the other metacarpal bones; its volar surface is concave from above downward.
The base presents a concavo-convex surface, for articulation with the greater multangular; it has no facets on its sides, but on its radial side is a tubercle for the insertion of the Abductor pollicis longus.
The head is less convex than those of the other metacarpal bones, and is broader from side to side than from before backward.