The ECRB is the most clinically important of the wrist extensors — it produces pure wrist extension without radial or ulnar deviation, optimising grip mechanics. It is the primary tendon involved in lateral epicondylitis (tennis elbow).
| Origin | Lateral epicondyle — from the common extensor origin, just medial to ECRL |
|---|---|
| Insertion | Base of the third metacarpal — dorsal surface |
| Nerve Supply | Posterior interosseous nerve (PIN, C7, C8) |
| Blood Supply | Radial recurrent artery |
| Actions | Extends the wrist — equal radial and ulnar contribution, producing pure dorsiflexion; The most important wrist extensor for grip |
|---|
ECRB is the primary tendon affected in tennis elbow — the degenerative change (angiofibroblastic hyperplasia) occurs at the ECRB origin on the lateral epicondyle. The Nirschl procedure removes the degenerate ECRB origin. ECRB is also the primary recipient of tendon transfers in radial nerve palsy reconstruction.
Palpated on the dorsoradial forearm during resisted pure wrist extension.
Degenerative angiofibroblastic change at the ECRB origin on the lateral epicondyle producing lateral elbow pain with grip and wrist extension, the most common cause of tennis elbow.
