Muscle
Abductor pollicis longus
Moves the thumb at its base
High-yield
The two tendons in wrist extensor compartment 1 are abductor pollicis longus and extensor pollicis brevis. They mark the radial edge of the anatomical snuffbox.
Overview
This deep forearm muscle pulls on the first metacarpal to move the thumb away from the hand. Its tendon reaches the wrist beside extensor pollicis brevis.
Reference facts
- Origin
- Back of the radius and ulna, with the intervening interosseous membrane
- Insertion
- Radial side of the first metacarpal base; additional tendon slips vary
- Action
- Abducts and helps extend the thumb at the carpometacarpal joint
- Innervation
- Posterior interosseous nerve, commonly described with C7-C8 contributions
- Blood supply
- Branches of the posterior interosseous artery
Clinical correlation
De Quervain tenosynovitis affects the tendons and sheath in this first compartment. Pain near the radial styloid may increase with thumb movement or gripping; the diagnosis requires clinical assessment.
Frequently asked questions
What does the abductor pollicis longus do?
The abductor pollicis longus abducts and helps extend the thumb at the carpometacarpal joint.
What nerve innervates the abductor pollicis longus?
Posterior interosseous nerve, commonly described with C7-C8 contributions.
Where does the abductor pollicis longus attach?
Origin: Back of the radius and ulna, with the intervening interosseous membrane. Insertion: Radial side of the first metacarpal base; additional tendon slips vary.
What is the blood supply of the abductor pollicis longus?
Branches of the posterior interosseous artery.