Tendon Sheath of the Extensor Carpi Ulnaris, Posterior View

Description

Running along the dorsoulnar wrist, the extensor carpi ulnaris (ECU) tendon is shown within its synovial tendon sheath as it courses distally toward its insertion on the base of the fifth metacarpal. The sheath sits superficial to the distal ulna and ulnar head, crossing the radiocarpal region on the posterior aspect, with the fifth metacarpal and the ulnar-side carpal bones (triquetrum and pisiform region) providing adjacent bony landmarks. Phalanges, metacarpals, and the two carpal rows are rendered to orient the tendon’s line of pull relative to the wrist and ulnar margin. Clinically, the ECU sheath matters because the tendon is constrained in the sixth dorsal compartment and stabilized by a subsheath near the ulnar groove, a setup that predisposes to ECU tendinopathy and subsheath tears with forceful supination, ulnar deviation, and wrist extension. Athletes often present with snapping ECU from tendon subluxation over the ulnar head, and this posterior-dorsoulnar perspective clarifies why pain localizes just distal to the ulnar styloid and can worsen during the ECU synergy test. A small structure. Frequent consequences. Use this artwork when teaching wrist extensor compartment anatomy in gross anatomy, hand surgery, or sports medicine modules, and when illustrating dorsal ulnar-sided wrist pain in textbooks, journal figures, and patient-facing surgical consent materials for ECU stabilization or tenosynovectomy. It also pairs well with ultrasound or MRI discussions that track fluid within the ECU tendon sheath and evaluate compartmental pathology. Anatomical accuracy verified by SciePro's Medical Advisory Board.