Tendon of extensor pollicis longus

The tendon of extensor pollicis longus muscle is a long and slender tendon that takes a distinctive path across the wrist and hand. As it approaches the wrist, the extensor pollicis longus tendon passes obliquely around the dorsal (Lister's) tubercle of the radius, using this bony prominence as a critical pulley. It then travels through the third dorsal extensor compartment, lying beneath the extensor retinaculum to prevent bowstringing. Continuing towards the thumb, the tendon crosses superficially over the tendons of the extensor carpi radialis longus and brevis. Notably, the extensor pollicis longus tendon forms the medial (ulnar) border of the anatomical snuffbox, a key surface landmark on the dorsolateral aspect of the wrist. The tendon then proceeds to its insertion at the dorsal base of the distal phalanx of the thumb, typically via the dorsal aponeurosis, allowing for precise and independent thumb motion.

For details, refer to the extensor pollicis longus muscle.