Muscle
Abductor pollicis brevis
Lifts the thumb out of the plane of the palm
High-yield
Palmar abduction uses the recurrent median nerve branch. Distinguish this movement from spreading the thumb sideways in the palm's plane.
Overview
This superficial thenar muscle produces palmar abduction: the thumb moves forward from a flat palm. Its pull helps position the thumb before it meets another fingertip.
Reference facts
- Origin
- Flexor retinaculum and the scaphoid and trapezium tubercles
- Insertion
- Radial side of the thumb's proximal phalanx at its base
- Action
- Produces palmar abduction of the thumb
- Innervation
- Recurrent median nerve branch, mainly C8–T1
- Blood supply
- Radial artery, through its superficial palmar branch
Clinical correlation
Carpal tunnel syndrome can cause thumb weakness. With severe or longstanding median nerve compression, the thenar pad may lose muscle bulk; wasting is not present in every case.
Frequently asked questions
What does the abductor pollicis brevis do?
The abductor pollicis brevis produces palmar abduction of the thumb.
What nerve innervates the abductor pollicis brevis?
The abductor pollicis brevis is innervated by the recurrent median nerve branch, mainly C8–T1.
Where does the abductor pollicis brevis attach?
The abductor pollicis brevis originates from the flexor retinaculum and the scaphoid and trapezium tubercles and inserts on the radial side of the thumb's proximal phalanx at its base.
What is the blood supply of the abductor pollicis brevis?
The abductor pollicis brevis is supplied by the radial artery, through its superficial palmar branch.