Lunate bone

The lunate bone may be distinguished by its deep concavity and crescentic outline. It is situated in the center of the proximal row of the carpus, between the scaphoid and triangular. The superior surface, convex and smooth, articulates with the radius. The inferior surface is deeply concave, and of greater extent from before backward than transversely: it articulates with the head of the capitate, and, by a long, narrow facet (separated by a ridge from the general surface), with the hamate. The dorsal and volar surfaces are rough, for the attachment of ligaments, the former being the broader, and of a somewhat rounded form. The lateral surface presents a narrow, flattened, semilunar facet for articulation with the scaphoid. The medial surface is marked by a smooth, quadrilateral facet, for articulation with the triquetrum.

The lunate articulates with five bones: the radius proximally, capitate and hamate distally, scaphoid laterally, and triangular medially.