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The hamate is a wedge-shaped bone with a curved hook-like process projecting laterally from its palmar surface. Its palmar and dorsal surfaces are roughened by the attachment of ligaments. The remaining surfaces, proximal, distal, lateral, and medial, form primarily smooth facets for articulation with neighboring bones.

This term comes from the Latin hamatus meaning hooked or crooked. The bone receives its name from the prominent hook-like process on the palmar surface of the bone. Historically, synonymous names used for this bone have been the unciforme and cuneiforme.

The hamate bone articulates with five bones: the lunate, triquetral, capitate, fourth metacarpal, and fifth metacarpal. The proximal most point of the bone forms the tip of the wedge. At this point, a small articular facet occurs for the lunate bone. The medial surface is convex proximally and concave distally for articulation with the triquetral bone. The lateral surface forms a broad, notched articular facet for reception of the capitate bone. Its distal surface forms a slight ridge that divides this aspect of the bone into two articular facets, a lateral facet for the fourth metacarpal and medial facet for the fifth metacarpal.

The hamate ossifies from a single center that arises during the third postnatal month. It is the second carpal bone to ossify.

Os hamatum