Final answer:
The abductor pollicis longus and extensor pollicis brevis muscles in the deep posterior compartment of the forearm move the thumb.
Step-by-step explanation:
The muscles in the deep posterior compartment of the forearm that move the thumb are the abductor pollicis longus and extensor pollicis brevis. These muscles originate on the radius and ulna and are responsible for moving the thumb sideways towards the body, extending the thumb, and moving the hand sideways towards the body.
In contrast, the superficial posterior compartment of the forearm muscles do not directly move the thumb. They include the extensor radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris. These muscles primarily extend the wrist and move the hand and fingers, but do not have a direct effect on thumb movement.