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Hook of the Hamate

hamulus ossis hamati

The hook of the hamate is a curved bony projection from the palmar surface of the hamate, forming the medial wall of the carpal tunnel and the lateral boundary of Guyon canal. It provides attachment for the flexor retinaculum (transverse carpal ligament), the pisohamate and pisometacarpal ligaments, and the opponens digiti minimi. The hook projects approximately 1.5 cm from the hamate body and is palpable in the hypothenar eminence.

Region: Hand & Wrist

Clinical Relevance

Clinical Notes

The hook of the hamate is the most commonly fractured carpal bone in racquet sports, golf, and batting sports, where the butt of the handle strikes directly during a mishit. Fracture produces hypothenar pain and a tender point directly over the hook (approximately 2 cm distal and radial to the pisiform). Plain radiographs require a carpal tunnel view; CT is the gold standard for diagnosis. The hook is adjacent to the ulnar nerve deep branch and ulnar artery, both at risk from fracture displacement or callus. Non-union is common and managed with hook excision.

Pathology

Common Injuries & Conditions

Hook of Hamate Fracture

Direct impact from a racquet or bat handle fractures the hamate hook, producing hypothenar pain and point tenderness over the hook with grip weakness; CT confirms diagnosis, and symptomatic non-unions are treated by hook excision rather than fixation.

Ulnar Nerve Compression at Hook

Hamate hook fractures, hypertrophied muscles, or ganglion cysts in Guyon canal compress the deep branch of the ulnar nerve against the hook, producing motor weakness of intrinsic hand muscles without sensory loss in the distal ulnar territory.