Proper palmar digital branches of ulnar nerve

At a glance

English

Proper palmar digital branches of ulnar nerve

Latin (TA2)

Rami digitales palmares proprii nervi ulnaris

System

Nerve

Region

Upper limb

Side

Paired, left and right

About the proper palmar digital branches of ulnar nerve

The ulnar nerve enters the hand through the ulnar canal, beside the pisiform, and splits there into a deep motor branch and a superficial branch. The superficial branch supplies palmaris brevis and then gives the digital nerves of the ulnar side of the hand. One proper palmar digital nerve runs directly to the medial, or ulnar, side of the little finger. The other branch, a common palmar digital nerve, runs towards the web between the ring and little fingers and divides into two proper digital nerves for their adjoining sides.

The arrangement in the fingers mirrors that of the median nerve on the radial side. Each proper digital nerve passes along the side of the flexor tendon sheath, lying on the palmar side of its digital artery. Near the base of the proximal phalanx it gives a dorsal branch that supplies the back of the finger beyond the proximal joint, including the nail bed. At the fingertip it divides into branches for the pulp and for the tissue around the nail. The common nerve usually sends a small communicating branch across to the nearest common digital nerve of the median nerve, so the ring finger may be shared differently between the two nerves in different people.

These branches carry feeling from the palmar surface of the little finger and the ulnar half of the ring finger, and from the backs of their middle and distal segments. The rest of the dorsal skin of these fingers is supplied by the dorsal branch of the ulnar nerve. The digital nerves contain no motor fibres; the small muscles on this side of the hand are served by the deep branch.

Testing sensation at the tip of the little finger is a reliable way to check the ulnar nerve, since this spot is almost never supplied by any other nerve. A lesion at the wrist or in the ulnar canal numbs these digits on the palmar side while sparing the back of the hand, whose dorsal branch arose higher up. Cuts on the ulnar border of the little finger, a common injury from knives and glass, may divide the outer digital nerve, and the numb strip that results is a common reason for nerve repair.

Course and supply

Arises from

From the ulnar nerve's superficial branch in the palm, directly or through a common palmar digital nerve.

Ends in

End in the pulp and nail bed of the little finger and the ulnar half of the ring finger.

Supplies

Purely sensory: supply the palmar skin of the little finger and ulnar half of the ring finger and the dorsal skin over their middle and distal phalanges.