Extensor Pollicis Longus Tendon Under the Skin, Posterior View

Description

Dorsal skin and superficial fascia are rendered translucent to trace the extensor pollicis longus tendon as it crosses the posterior wrist and hand toward the distal phalanx of the thumb. Proximally, the tendon passes deep to the extensor retinaculum within the third dorsal compartment, then angles obliquely from the ulnar side of the dorsum toward the radial thumb, skirting the dorsal aspect of the first metacarpal and continuing to the base of the distal phalanx. Adjacent extensor tendons to the index and middle digits course more centrally over the metacarpals, while superficial dorsal veins run within the subcutaneous tissue plane overlying the retinacular region. That oblique change in direction is the teaching point. At the dorsal distal radius the extensor pollicis longus tendon uses Lister tubercle as a pulley, a location that concentrates friction and makes the tendon prone to attritional rupture after minimally displaced distal radius fractures, inflammatory tenosynovitis, or corticosteroid exposure. The same tendon also forms the ulnar border of the anatomical snuffbox, so its relationship to the first dorsal compartment (abductor pollicis longus and extensor pollicis brevis) helps distinguish snuffbox tenderness from first-compartment pain patterns during clinical exam. Small space. Big consequences. Use this plate to support upper limb anatomy teaching on dorsal extensor compartments, tendon sheaths, and thumb extension mechanics in hand surgery courses, occupational therapy curricula, and exam-prep atlases. It also fits well in chapters on distal radius fracture complications, tendon transfer planning (EIP to EPL), and surface anatomy of the anatomical snuffbox for emergency and sports medicine references. Anatomical accuracy verified by SciePro's Medical Advisory Board.