Muscle
Flexor pollicis longus
Flexes the thumb IP joint
High-yield
Flexes thumb IP joint; anterior interosseous nerve (AIN). Weak 'OK sign' with AIN palsy.
Overview
A deep anterior forearm muscle that flexes the interphalangeal joint of the thumb, supplied by the anterior interosseous nerve.
Reference facts
- Origin
- Anterior surface of the radius and adjacent interosseous membrane
- Insertion
- Base of the distal phalanx of the thumb
- Action
- Flexes the interphalangeal and metacarpophalangeal joints of the thumb
- Innervation
- Anterior interosseous branch of the median nerve (C8, T1)
- Blood supply
- Anterior interosseous and radial arteries
Frequently asked questions
What does the flexor pollicis longus do?
The flexor pollicis longus flexes the interphalangeal and metacarpophalangeal joints of the thumb.
What nerve innervates the flexor pollicis longus?
The flexor pollicis longus is innervated by the anterior interosseous branch of the median nerve (C8, T1).
Where does the flexor pollicis longus attach?
The flexor pollicis longus originates from the anterior surface of the radius and adjacent interosseous membrane and inserts on the base of the distal phalanx of the thumb.
What is the blood supply of the flexor pollicis longus?
The flexor pollicis longus is supplied by the anterior interosseous and radial arteries.