Dorsal digital branches of ulnar nerve

At a glance

English

Dorsal digital branches of ulnar nerve

Latin (TA2)

Rami digitales dorsales nervi ulnaris

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the dorsal digital branches of ulnar nerve

The dorsal digital branches are the end branches of the dorsal (posterior cutaneous) branch of the ulnar nerve. That branch leaves the main ulnar nerve in the lower forearm, roughly 5 cm above the wrist, winds backwards beneath the tendon of flexor carpi ulnaris and pierces the deep fascia on the medial side of the wrist. On the back of the hand it supplies the skin over the medial part of the dorsum and then breaks up into digital branches.

Usually two or three dorsal digital nerves are formed. One runs along the ulnar (outer) border of the little finger. A second divides to supply the facing sides of the ring and little fingers. A further twig commonly passes towards the web between the ring and middle fingers, where it joins a matching branch from the radial nerve's superficial branch; together they share the supply of the adjoining sides of these two fingers. Dorsal digital arteries accompany the branches along the backs of the fingers.

Their territory is the skin on the back of the little finger, the ulnar half of the ring finger and, in part, the adjacent side of the middle finger, but only as far as the proximal or middle segments. The skin over the backs of the end segments and the nail beds is supplied instead by the proper palmar digital nerves, which curl round from the front. The exact border with the radial nerve territory varies between people, and in some hands the radial nerve takes over more of the ring finger.

Because the dorsal branch leaves the ulnar nerve above the wrist, a lesion of the ulnar nerve at the wrist, such as compression in Guyon's canal, spares sensation on the back of the medial hand and fingers, while a lesion at the elbow does not. Testing this area therefore helps locate ulnar nerve damage. The branches can also be cut in wounds or surgery on the back of the hand, causing a small patch of numbness.

Course and supply

Arises from

Terminal branches of the ulnar nerve's dorsal branch, formed on the back of the hand.

Ends in

End in the dorsal skin of the ring and little fingers, with a twig joining the radial nerve's superficial branch near the middle finger.

Supplies

Sensory to the skin on the back of the little finger, the ulnar half of the ring finger and part of the middle finger, excluding the tips and nail beds.

Blood supply

Run alongside the dorsal digital arteries.