Flexor Pollicis Longus
Musculus flexor pollicis longus
Flexor pollicis longus is the only forearm muscle that flexes the tip of the thumb, supplying the thumb-side force behind pinch and hook grips. It contributes meaningfully to crushing and pinch-grip strength used in plate pinches, thick-bar holds, and climbing. It lies deep in the anterior compartment alongside flexor digitorum profundus.
- Actions
- Flexion of the interphalangeal and metacarpophalangeal joints of the thumb, Assists thumb flexion at the carpometacarpal joint
- Origin
- Anterior surface of the middle of the radius and the adjacent interosseous membrane
- Insertion
- Palmar base of the distal phalanx of the thumb
- Innervation
- Anterior interosseous branch of the median nerve (C8, T1)
- Blood supply
- Anterior interosseous artery
Synergists Flexor Pollicis Brevis
Antagonists Extensor Pollicis LongusExtensor Pollicis Brevis