Posterior Perspective of the Extensor Carpi Ulnaris Muscle Beneath the Skin

Description

Running along the dorsoulnar forearm, the extensor carpi ulnaris (ECU) is shown superficially beneath the skin from its proximal attachments near the lateral epicondyle via the common extensor tendon and along the posterior border of the ulna, then distally as a tendon approaching the ulnar side of the wrist. Medial to the extensor digiti minimi and extensor digitorum, the ECU belly tracks close to the subcutaneous ulna, while the radius remains lateral on the thumb side. At the distal forearm the ECU tendon passes deep to the extensor retinaculum within the sixth dorsal compartment and continues to its insertion at the base of the fifth metacarpal. Clear dorsal landmarks. Ulnar sided wrist pain often turns on ECU anatomy. This posterior perspective matches the clinical exam position for ECU synergy testing and helps explain why tendinopathy and tenosynovitis localize just proximal to the ulnar head where the tendon transitions into its fibro-osseous tunnel, and why instability or subluxation can occur when the ECU subsheath fails during supination with ulnar deviation. Surgeons also reference this relationship when approaching the distal radioulnar joint and TFCC, since the ECU compartment sits immediately dorsal to these structures and can be a pain generator or a landmark. Use this artwork in upper limb gross anatomy teaching (forearm extensor compartments), sports medicine resources on dorsal compartment tendinopathies, or orthopaedic and hand surgery materials covering ECU tendinosis, snapping ECU, and sixth compartment release. It also suits patient education for dorsal ulnar wrist symptoms when paired with surface anatomy and exam maneuvers. Anatomical accuracy verified by SciePro's Medical Advisory Board.