Extensor Carpi Ulnaris

Joe Muscolino

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The extensor carpi ulnaris is seen. The extensor digiti minimi has been ghosted in.

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:


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



  • 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.





  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.