Final answer:
The abductor pollicis longus is a muscle in the deep posterior compartment of the forearm that abducts the thumb. It is innervated by the posterior interosseous nerve and receives its blood supply from the posterior interosseous artery.
Step-by-step explanation:
The abductor pollicis longus is a muscle located in the deep posterior compartment of the forearm. It inserts into the first metacarpal bone and its main action is to abduct the thumb, which means it moves the thumb away from the midline of the hand. The abductor pollicis longus is innervated by the posterior interosseous nerve and receives its blood supply from the posterior interosseous artery.