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