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Guyon Canal

canalis Guyoni

Guyon canal (ulnar canal) is the fibro-osseous tunnel at the wrist through which the ulnar nerve and artery pass from the forearm to the hand. Its floor is the flexor retinaculum and the pisohamate ligament; its roof is the palmar carpal ligament (a continuation of Camper fascia over the wrist). The medial wall is the pisiform; the lateral wall the hook of hamate. Within the canal, the ulnar nerve divides into its superficial (sensory) and deep (motor) branches.

Region: Hand & Wrist

Clinical Relevance

Clinical Notes

Guyon canal syndrome produces ulnar nerve compression at the wrist with patterns depending on the level of compression. Zone 1 (proximal to bifurcation): both motor and sensory deficit. Zone 2 (deep branch): pure motor deficit with intrinsic weakness and clawing without sensory loss. Zone 3 (superficial branch): pure sensory deficit in the little and ring fingers. Causes include ganglion cysts, hypothenar hammer syndrome (repetitive ulnar artery trauma), hook of hamate fracture, and cycling pressure. Distinguished from cubital tunnel by preserved dorsal ulnar sensation (dorsal cutaneous branch arises above the canal).

Pathology

Common Injuries & Conditions

Zone 2 Guyon Canal Compression

A ganglion cyst at the hook of hamate or hook fracture in the deep Guyon canal zone 2 compresses the deep motor branch of the ulnar nerve, producing pure intrinsic motor weakness with ring and little finger clawing but preserved sensory function; MRI or ultrasound confirms the compressive lesion.