Ulnar nerve

The ulnar nerve is one of the terminal branches of the brachial plexus and has motor and sensory supply to the forearm and hand.

Origin

The ulnar nerve originates as a terminal branch of the medial cord of the brachial plexus with nerve root fibres from C8-T1.

Course
Arm

In the arm, the ulnar nerve runs medial to the axillary artery and subsequently the brachial artery on the coracobrachialis muscle in the anterior compartment.  The nerve passes to the posterior compartment through the medial intermuscular septum distally running with the superior ulnar collateral artery. Further on, it runs between medial head of triceps brachii muscle and the medial intermuscular septum to pass posterior to the medial humeral epicondyle in the superficial condylar groove (cubital tunnel).

Forearm

The ulnar nerve enters the forearm from the arm via the two heads of flexor carpi ulnaris (FCU) muscle. It subsequently lies superficial to flexor digitorum profundus and deep to FCU and medial to the ulnar artery.  At the wrist, the ulnar nerve runs lateral to the tendon of FCU.

Hand

The ulnar nerve enters the hand superficial to the flexor retinaculum and inside Guyon's canal. Then it divides into its terminal branches at the level of the pisiform bone.

Prior to passing the flexor retinaculum at the wrist, the ulnar nerve gives off the dorsal cutaneous branch. 

Terminal branches
  • palmar cutaneous branch
  • branch to palmaris brevis
  • superficial terminal branch
  • deep terminal branch

The ulnar nerve has both sensory and motor supply:

  • motor: forearm flexors, intrinsic hand muscles
  • sensory
    • articular innervation to elbow, wrist, carpal and phalangeal joints
    • cutaneous innervation to ulnar aspect of the hand, 5th finger, medial 4th finger

Upper limb anatomy
Share article

Article Information

rID: 24690
Section: Anatomy
Tags: refs, cases
Synonyms or Alternate Spellings:
  • Ulna nerve

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Figure 1: ulnar nerve
    Drag here to reorder.
  • Drag
    Figure 2: brachial plexus
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.