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Dorsal Cutaneous Branch of the Ulnar Nerve

ramus cutaneus dorsalis nervi ulnaris

The dorsal cutaneous branch of the ulnar nerve arises from the ulnar nerve approximately 5-7 cm proximal to the wrist, passes posterior to the ulnar head to supply the dorsal skin of the ulnar hand including the dorsum of the little finger and the ulnar half of the ring finger to the level of the PIP joints, and may also supply the dorsal ulnar wrist skin. Its origin proximal to Guyon's canal means it is preserved in Guyon canal ulnar nerve compression.

Region: Hand & Wrist

Clinical Relevance

Clinical Notes

The dorsal cutaneous branch of the ulnar nerve is the key nerve in distinguishing distal from proximal ulnar nerve lesions: if the dorsal ulnar hand sensation is preserved in a patient with ulnar motor deficit and ring-little finger palmar numbness, the lesion is within Guyon's canal (distal to the branch takeoff). If dorsal ulnar hand sensation is also absent, the lesion is at the cubital tunnel or more proximal. The branch is at risk in TFCC repair, distal ulna resection, and wrist approaches requiring ulnar-side skin incisions.

Pathology

Common Injuries & Conditions

Dorsal Ulnar Cutaneous Branch in TFCC Surgery

Dorsal wrist approaches for TFCC tear repair and distal radioulnar joint procedures risk the dorsal cutaneous branch of the ulnar nerve as it crosses from the ulnar forearm to the dorsal hand over the ulnar head; its injury produces dorsal ulnar hand numbness and painful neuroma requiring careful incision planning along the fifth compartment to avoid the nerve.