Upper limb
Abductor Pollicis Longus
Musculus abductor pollicis longus
- Origin
- Posterior surface of the radius and ulna and the interposed interosseous membrane
- Insertion
- Base of the 1st metacarpal bone, radial side
- Function
- Abduction and (partly) extension of the carpometacarpal joint of the thumb; assists radial abduction of the wrist
- Innervation
- Radial nerve (deep branch / posterior interosseous nerve)
- Movement & chain
- Together with extensor pollicis brevis, forms the radial border of the anatomical snuffbox; both muscles work together in spreading the thumb during grip movements.
- Palpation
- The tendon can be readily traced on the radial side of the wrist, just proximal to the anatomical snuffbox, with the thumb extended and abducted.
- Clinical
- Together with extensor pollicis brevis, involved in De Quervain's disease (stenosing tenosynovitis of the first dorsal compartment), with pain on thumb movement and a positive Finkelstein test.
- Segmental innervation
- Radial nerve, C7-C8.
- In clinical practice
- The tendon, together with extensor pollicis brevis, forms the radial border of the anatomical snuffbox, an important landmark in physical examination for a scaphoid fracture.
- Region in the model
- Upper limb