Dorsal branch of ulnar nerve
Ramus dorsalis nervi ulnaris
A cutaneous branch of the ulnar nerve that leaves it above the wrist to supply the skin over the medial dorsum of the hand.
At a glance
- English
- Dorsal branch of ulnar nerve
- Latin (TA2)
- Ramus dorsalis nervi ulnaris
- System
- Nerve
- Region
- Upper limb
- Side
- Paired, left and right
About the dorsal branch of ulnar nerve
The dorsal branch of the ulnar nerve is the cutaneous nerve for the medial part of the back of the hand. It leaves the ulnar nerve in the lower forearm, roughly five centimetres above the wrist, well before the main nerve passes through the ulnar canal.
From its origin it runs backwards and downwards beneath the tendon of flexor carpi ulnaris, curving round the medial side of the lower ulna. It pierces the deep fascia to become subcutaneous and continues along the medial edge of the dorsum of the wrist and hand, crossing near the ulnar styloid process.
On the dorsum it divides into dorsal digital nerves. Usually one runs along the ulnar border of the little finger, and another serves the borders of the ring and little fingers that face each other. A further twig often joins a branch of the superficial radial nerve to share in supplying the facing sides of the ring and middle fingers. Its branches to the metacarpal region also connect with twigs of the superficial radial nerve. The dorsal digital nerves usually reach only the proximal part of each finger; the skin over the distal phalanges is supplied from the palmar side.
Its separate origin above the wrist is useful in diagnosis. In compression of the ulnar nerve at Guyon's canal the back of the hand keeps normal feeling, because this branch has already left. In injury at the elbow the back of the ulnar side of the hand is numb as well. The nerve can be cut in operations on the distal ulna and in wrist arthroscopy through ulnar-side portals.
Course and supply
- Arises from
- The ulnar nerve in the distal forearm, about five centimetres above the wrist.
- Ends in
- Ends in dorsal digital nerves to the little finger, the cleft between little and ring fingers, and sometimes the ring-middle cleft.
- Supplies
- Sensory to the skin over the medial dorsum of the hand and the proximal dorsal skin of the little finger and the ring finger; no muscle supply.
Anthromica
See the dorsal branch of ulnar nerve where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
