The triceps brachii extend the forearm. The pronator teres and quadratus control pronation, or rotation of the forearm so that the palm faces downward.

What is the prime mover of forearm extension?

triceps brachii. prime mover of forearm extension, assists in arm adduction, stabilizes shoulder. biceps brachii.

Which muscles extend the forearm quizlet?

Triceps brachii is only muscle on posterior side of the arm, and it extends the forearm.