Extensor carpi ulnaris (Musculus extensor carpi ulnaris)
Educational content only — not medical advice.
Anatomy
The most medial posterior-compartment muscle; its tendon runs in the sixth compartment in a groove behind the ulnar head — its own sheath makes it a true stabiliser of the distal radioulnar joint during rotation.
Origin & insertion
Lateral epicondyle via the common tendon and the posterior ulnar border.
Action
Extends and ulnarly deviates the wrist (paired with flexor carpi ulnaris) and holds the ulnar head in place during forceful rotation.
Innervation
Radial nerve — posterior interosseous branch (C7–C8).
Clinical notes
Tendon subluxation out of its groove after wrist sprains shows as repeated snapping over the ulnar head on key-turning rotation; treatment is ligamentous or sheath conversion surgery.
Related structures
Educational references
FAQ
What is the role of the Extensor carpi ulnaris?
The most medial posterior-compartment muscle; its tendon runs in the sixth compartment in a groove behind the ulnar head — its own sheath makes it a true stabiliser of the distal radioulnar joint during rotation.
Why is the Extensor carpi ulnaris clinically important?
Tendon subluxation out of its groove after wrist sprains shows as repeated snapping over the ulnar head on key-turning rotation; treatment is ligamentous or sheath conversion surgery.
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details