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
Frequently asked questions
What does the extensor pollicis longus do?
The extensor pollicis longus extends the distal phalanx of the thumb; extends and adducts the thumb.
What nerve innervates the extensor pollicis longus?
The extensor pollicis longus is innervated by the posterior interosseous nerve (C7, C8).
Where does the extensor pollicis longus attach?
The extensor pollicis longus originates from the posterior surface of the ulna and interosseous membrane and inserts on the base of the distal phalanx of the thumb.
What is the blood supply of the extensor pollicis longus?
The extensor pollicis longus is supplied by the posterior interosseous artery.