Common Extensor Tendon at Lateral Epicondyle

tendo communis extensorum ad epicondylum lateralem

The common extensor tendon is the conjoint origin of the extensor carpi radialis brevis, extensor digitorum communis, extensor digiti minimi, and extensor carpi ulnaris from the lateral epicondyle. The ECRB origin is the deepest and most commonly degenerated component. The tendon blends with the lateral collateral ligament complex at its posterior margin.

Region: Upper Arm

Clinical Relevance

Clinical Notes

Lateral epicondylitis (tennis elbow) is a degenerative tendinopathy of the common extensor origin — predominantly the ECRB — at the lateral epicondyle. It is the most common cause of lateral elbow pain, affecting 1-3% of the population. Diagnosis is clinical: tenderness at the lateral epicondyle and pain with resisted wrist extension and middle finger extension. High-volume injection, platelet-rich plasma, and progressive loading all target this tendon origin. The LCL complex lies immediately posterior and must not be injected inadvertently.

Pathology

Common Injuries & Conditions

Lateral Epicondylitis (Tennis Elbow)

Degenerative tendinopathy of the common extensor origin, predominantly ECRB, producing lateral elbow pain reproduced by resisted wrist extension and middle finger extension, managed by progressive loading and targeted injection.

Common Extensor Tendon Rupture

Complete tear of the common extensor origin from forced wrist flexion or direct trauma, producing sudden lateral elbow pain and weakness of wrist extension, requiring surgical repair in active patients.