Common Extensor Tendon (Elbow)

tendo musculi extensoris communis

The common extensor tendon is the shared origin of the extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris at the lateral epicondyle. The ECRB component is most consistently implicated in lateral epicondylalgia (tennis elbow), where histological analysis shows angiofibroblastic degeneration rather than classical inflammation. The common extensor tendon origin spans the anterolateral aspect of the lateral epicondyle.

Region: Upper Arm

Biomechanics

Function & Actions

Common origin of the wrist and finger extensors — transmits extensor force from all lateral forearm muscles

Clinical Relevance

Clinical Notes

Lateral epicondylalgia involves the ECRB origin in 85 to 90 percent of cases with the EDC in most of the remainder. The Cozen test (resisted wrist extension with the elbow extended) and Mill test (passive wrist flexion with the elbow extended) reproduce the lateral epicondyle pain. Ultrasound shows tendon thickening, hypoechoic regions, and neovascularisation at the ECRB origin. Eccentric loading, corticosteroid injection, and PRP injection have the strongest evidence base.

Pathology

Common Injuries & Conditions

Lateral Epicondylalgia

ECRB and common extensor tendon degeneration at the lateral epicondyle producing lateral elbow pain reproduced by resisted wrist extension and passive wrist flexion, managed with eccentric loading and injection.