flexor pollicis longus (muscle)
flex·or pol·li·cis lon·gus (mus·cle)
[TA]muscle of deep layer of anterior (flexor) compartment of forearm; origin, anterior surface of middle third of radius; insertion, palmar aspect of distal phalanx of thumb; action, flexes thumb at interphalangeal joint; nerve supply, median (anterior interosseous).