The hamate is the most medial carpal bone of the distal row, positioned at the ulnar end of the row. This bone is easily distinguished by a non-articular hook-like projection called the hook or hamulus. It is found on the distal palmar aspect of the bone. The rest of the bone appears triangular-shaped.

The lateral aspect of the hook is deeply concave. Near the base of the hook can be present a groove that lodges the deep terminal branch of the ulnar nerve. Also, close to the hook are flexor tendons that go to the little finger. These structures can get damaged during injuries that affect the hook.

The hook also serves as an origin site of the opponens digiti minimi and flexor digiti minimi brevis muscles. Moreover, it is an attachment site for the flexor retinaculum. Finally, the pisohamate ligament attaches to the bone.

The hamate articulates with the fourth and fifth metacarpals distally, lunate and triquetral proximally and medially and the capitate laterally. Therefore, it has the following five articular surfaces:

Articular surface for capitate - large and covers almost all the lateral aspect of the bone;
Articular surface for lunate - small and smooth;
Articular surface for triquetral - broad, strip-like surface; appears convex proximally and concave distally;
Articular surface for fifth metacarpal - square-shaped; larger than the facet for the fifth metacarpal bone;
Articular surface for fourth metacarpal - square-shaped; smaller than the facet for the fourth metacarpal bone.

The proximal end of the bone is thin and wedge-shaped. It only comes into direct contact with the lunate when the hand is adducted.

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Hamate