Common palmar digital branches of ulnar nerve

At a glance

English

Common palmar digital branches of ulnar nerve

Latin (TA2)

Rami digitales palmares communes nervi ulnaris

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the common palmar digital branches of ulnar nerve

In the hand the ulnar nerve passes into the palm through Guyon's canal, on the radial side of the pisiform, and divides into a deep, mainly motor branch and a superficial, mainly sensory branch. The superficial branch gives a short twig to palmaris brevis and then splits into two digital nerves. One is the proper palmar digital nerve to the ulnar side of the little finger. The other is the common palmar digital nerve described here.

The common palmar digital nerve of the ulnar nerve runs distally in the palm, superficial to the flexor tendons of the little and ring fingers and deep to the palmar aponeurosis and the superficial palmar arch. Near the web separating the ring finger from the little finger it divides into two proper palmar digital nerves, which serve the adjoining sides of those two fingers. Before dividing it usually sends a communicating branch across to the nearest common palmar digital nerve of the median nerve, linking the two systems.

Together with the proper digital nerve to the outer side of the little finger, it gives sensation to the palmar surface of the little finger and the ulnar half of the ring finger, and to the backs of their terminal segments and nail beds. This is the classic ulnar territory tested when the nerve is examined. The skin of the hypothenar eminence itself is supplied by the palmar cutaneous branch, which leaves the ulnar nerve in the forearm.

Because the superficial branch lies close to the surface over the hook of the hamate, it can be injured by a fall on the heel of the hand or by repeated pressure, as in long-distance cycling, causing numbness of the little finger and half the ring finger. Pressure at the elbow usually causes the same numbness plus weakness of the small hand muscles. The communication with the median nerve explains why sensory loss after injury to either nerve may be less sharply limited than textbook maps suggest.

Course and supply

Arises from

Arises in the palm from the ulnar nerve's superficial branch, just beyond Guyon's canal.

Ends in

Divides close to the fourth web space into two proper palmar digital nerves for their adjoining sides; sends a communicating branch to the median nerve.

Supplies

Sensory to the palmar skin of the adjoining sides of the ring and little fingers, including the dorsal skin of their tips and nail beds.