The capitate bone (os magnum) is the largest of the carpal bones, and occupies the center of the wrist. It presents, above, a rounded portion or head, which is received into the concavity formed by the scaphoid and lunate; a constricted portion or neck; and below this, the body.
The superior surface is round, smooth, and articulates with the lunate.
The inferior surface is divided by two ridges into three facets, for articulation with the second, third, and fourth metacarpal bones, that for the third being the largest.
The dorsal surface is broad and rough.
The volar surface is narrow, rounded, and rough, for the attachment of ligaments and a part of the Adductor pollicis obliquus.
The lateral surface articulates with the lesser multangular by a small facet at its anterior inferior angle, behind which is a rough depression for the attachment of an interosseous ligament. Above this is a deep, rough groove, forming part of the neck, and serving for the attachment of ligaments; it is bounded superiorly by a smooth, convex surface, for articulation with the navicular.
The medial surface articulates with the hamate by a smooth, concave, oblong facet, which occupies its posterior and superior parts; it is rough in front, for the attachment of an interosseous ligament.
The capitate articulates with seven bones: the scaphoid and lunate proximally, the second, third, and fourth metacarpals distally, the trapezoid on the radial side, and the hamate on the ulnar side.