Ulnar nerve

Origin

Larger terminal branch of the medial cord, receiving fibres from (C7) C8 & T1.

Course

Descends the medial arm; passes posterior to the medial epicondyle of the humerus, then descends the ulnar side of the forearm to the hand.

Innervation

Flexor carpi ulnaris and ulnar half of flexor digitorum profundus; most intrinsic muscles of the hand

Skin of the hand medial to the axial line of digit 4.

The autonomous zone for the ulnar nerve is the distal phalanx of the little finger.  There is loss of abduction and adduction of all fingers.  Claw hand deformity of the hand results from hyperextension of the metacarpophalangeal joints and flexion of the interphalangeal joints.