Muscle
Extensor pollicis longus
Extends the thumb IP joint
High-yield
Forms the posterior border of the snuffbox; may rupture after a distal radius (Colles) fracture.
Overview
A deep muscle that extends the distal phalanx of the thumb; its tendon forms the posterior (ulnar) border of the anatomical snuffbox, hooking around Lister's tubercle.
Reference facts
- Origin
Posterior surface of the ulna and interosseous membrane
- Insertion
Base of the distal phalanx of the thumb
- Action
Extends the distal phalanx of the thumb; extends and adducts the thumb
- Innervation
Posterior interosseous nerve (C7, C8)
- Blood supply
Posterior interosseous artery