Muscle
Extensor carpi ulnaris
Wrist extension toward the ulna
High-yield
Its tendon travels through wrist extensor compartment 6 in a groove at the distal ulna. A surrounding subsheath helps keep it in place.
Overview
Running along the back of the forearm on its ulnar side, this muscle pulls on the fifth metacarpal. It contributes to both wrist motion and stability during a firm grip.
Reference facts
- Origin
- Humeral lateral epicondyle and the posterior border of the ulna
- Insertion
- Dorsal base of the fifth metacarpal
- Action
- Extends the wrist and produces ulnar deviation
- Innervation
- Posterior interosseous nerve, commonly C7-C8
- Blood supply
- Ulnar and posterior interosseous arterial branches
Clinical correlation
Damage to the tendon subsheath can allow the tendon to slip out of position. Pain or snapping on the ulnar side of the wrist may occur, particularly with forceful rotational activity.
Frequently asked questions
What does the extensor carpi ulnaris do?
The extensor carpi ulnaris extends the wrist and produces ulnar deviation.
What nerve innervates the extensor carpi ulnaris?
Posterior interosseous nerve, commonly C7-C8.
Where does the extensor carpi ulnaris attach?
The extensor carpi ulnaris originates from the humeral lateral epicondyle and the posterior border of the ulna and inserts on the dorsal base of the fifth metacarpal.
What is the blood supply of the extensor carpi ulnaris?
The extensor carpi ulnaris is supplied by the ulnar and posterior interosseous arterial branches.