extensor pollicis longus (muscle)

ex·ten·sor pol·li·cis lon·gus (mus·cle)

[TA] muscle of posterior (extensor) compartment of forearm; origin, posterior surface of middle of shaft of ulna; insertion, dorsal aspect of base of distal phalanx of thumb; action, extends distal phalanx of thumb; nerve supply, radial (posterior interosseous). Synonym(s): musculus extensor pollicis longus [TA], long extensor (muscle) of thumb, musculus extensor longus pollicis