Extensor Carpi Ulnaris Under the Skin, Posterior View

Description

Superficial dissection from a posterior perspective places the extensor carpi ulnaris along the dorsoulnar forearm, running inferiorly from the lateral epicondyle region and posterior border of the ulna toward the ulnar side of the wrist. Its muscle belly lies medial to extensor digitorum and lateral to the subcutaneous border of the ulna, then narrows into a tendon that courses beneath the extensor retinaculum in the sixth dorsal compartment. Distally, the tendon tracks over the ulnar head and inserts on the dorsal base of the fifth metacarpal, aligning with the ulnar styloid as a palpable landmark. Small-caliber dorsal vessels may be indicated in blue near the distal forearm and hand. Ulnar-sided wrist pain often turns on understanding this tendon’s relationship to the distal radioulnar joint and the triangular fibrocartilage complex, because the extensor carpi ulnaris subsheath contributes to stability while the tendon acts as a dynamic ulnar deviator and wrist extensor. This view offers the clearest perspective on why extensor carpi ulnaris tendinopathy, tenosynovitis, or traumatic subluxation can follow forceful supination with wrist flexion and ulnar deviation, the classic mechanism in tennis and golf, and why tenderness localizes just dorsal to the ulnar styloid. A frequent surgical landmark. Surgeons also reference the sixth compartment when releasing the extensor retinaculum or when planning approaches that must protect the dorsal cutaneous branch of the ulnar nerve in the distal forearm. Ideal for upper limb anatomy teaching in gross lab and surface anatomy modules, and for sports medicine, hand therapy, and orthopaedic publications addressing extensor compartment pathology and ulnar-sided wrist evaluation. It also fits patient-facing education on extensor carpi ulnaris tendon injury when paired with clinical photographs or ultrasound screenshots. Anatomical accuracy verified by SciePro's Medical Advisory Board.