Extensor Pollicis Longus Muscle as, Posterior View

Description

Running along the dorsoradial forearm into the hand, the extensor pollicis longus (EPL) muscle belly tapers into a long tendon that courses distally toward the thumb. From a posterior aspect, the tendon typically becomes superficial at the wrist, passing obliquely from the ulnar side of the distal radius toward the dorsal base of the thumb, crossing dorsal to the extensor carpi radialis longus and brevis tendons. Distally, the EPL tendon continues to the distal phalanx of the pollex, lying dorsal to the first metacarpal and thumb phalanges and acting across the metacarpophalangeal and interphalangeal joints. Bones of the carpus, metacarpals, and phalanges provide fixed landmarks around the tendon’s path. This posterior viewpoint matters because the EPL tendon is the medial border of the anatomic snuffbox and is a standard surface landmark for dorsal wrist procedures and tendon examinations. Clinically, EPL rupture is a known complication after nondisplaced distal radius fractures and can also follow corticosteroid injection or attritional wear where the tendon turns around Lister’s tubercle on the distal radius, leaving patients unable to extend the thumb interphalangeal joint. It is also the tendon most often transferred during reconstruction of chronic extensor pollicis brevis insufficiency or certain radial nerve palsy patterns. Use this artwork for upper-limb anatomy teaching on the extrinsic thumb extensors, for surgical atlases discussing dorsal approaches to the wrist and thumb, or for patient-facing education on EPL tendinopathy and rupture after distal radius injury. It also fits radiology correlation in ultrasound and MRI modules, where the EPL is traced in the third dorsal extensor compartment and assessed during dynamic thumb extension. Anatomical accuracy verified by SciePro's Medical Advisory Board.