Extensor pollicis longus
Arms
Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.
- Origin
- Back of the middle of the ulna and the interosseous membrane
- Insertion
- Base of the distal phalanx of the thumb
- Action
- Extends the thumb, including its tip joint
- Nerve supply
- Posterior interosseous nerve (radial nerve, C7–C8)
Its tendon hooks around a small bony bump on the back of the radius on its way to the thumb and forms the back edge of the anatomical snuffbox.
Extensor pollicis longus anatomy page →