Extensor Carpi Ulnaris

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The Extensor Carpi Ulnaris is in the Superficial Layer of the Posterior Compartment of the forearm. It is also a member of the Wrist Extensor Group; the muscles of the wrist extensor group are:

• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Extensor carpi ulnaris

The Extensor Carpi Ulnaris has two heads: Humeral head and Ulnar head.

ATTACHMENTS:

• Lateral epicondyle of the humerus via the common extensor belly/tendon to the radial side of the posterior hand.
  • The ulnar head attaches proximally onto the middle 1/3 of the posterior ulna.
  • The distal attachment is onto the posterior side of the base of the fifth metacarpal.

ACTIONS:

• Extends the hand at the wrist joint.
• Ulnar deviates the hand at the wrist joint.
• Extends the forearm at the elbow joint.
• Pronates the forearm at the radioulnar joints.

NOTES:

1. The extensor carpi ulnaris is often involved with lateral elbow tendinopathy (aka tennis elbow).
2. The humeral head of the extensor carpi ulnaris is much larger than the ulnar head.