Common Extensor Origin Tendon

tendo communis musculi extensorum

The common extensor origin is the conjoined tendinous attachment of the wrist and finger extensor muscles to the lateral epicondyle of the humerus. The extensor carpi radialis brevis (ECRB) is the dominant and most clinically relevant component, arising from the anterior-inferior face of the lateral epicondyle. Other contributors include extensor digitorum communis, extensor digiti minimi, and extensor carpi ulnaris, all originating from the lateral epicondyle or immediately adjacent lateral supracondylar ridge.

Region: Forearm

Clinical Relevance

Clinical Notes

Common extensor origin tendinopathy (lateral epicondylitis, tennis elbow) affects 1-3% of the population and is dominated by ECRB pathology, with intratendinous tears and angiofibroblastic hyperplasia at the ECRB origin. Diagnosis is clinical: point tenderness at the lateral epicondyle reproduced by wrist extension against resistance (Cozen test). Management progresses from physiotherapy and corticosteroid injection to PRP injection and surgical ECRB debridement. Lateral release surgery must avoid the LUCL to prevent iatrogenic PLRI. The common extensor origin is also affected in radial head fracture repair when the lateral approach splits through it.

Pathology

Common Injuries & Conditions

ECRB Tendinopathy at Common Extensor Origin

Angiofibroblastic degeneration of the extensor carpi radialis brevis at the anterior lateral epicondyle origin produces tennis elbow with maximum tenderness at the epicondyle reproduced by resisted wrist extension; PRP injection targets the tendinopathic ECRB origin directly under ultrasound guidance, and surgical debridement releases the diseased tissue via an open or arthroscopic approach.