Muscle · Elbow

Extensor carpi ulnaris

Musculus extensor carpi ulnaris

The wrist extensor on the little-finger side of the back of the forearm. Working alone it straightens the wrist and tips the hand toward the pinky; paired with flexor carpi ulnaris it produces pure ulnar deviation, and paired with the radial extensors it produces pure extension — a good illustration of how the wrist is steered by balancing muscles against one another rather than by any one of them. Its tendon runs in a groove on the ulna held by its own sheath, so it is a common source of pain on the ulnar side of the wrist in racket and stick sports.