Forearm pronation is produced by which muscles?

Forearm pronation is produced by which muscles?

• A. Pronator teres and pronator quadratus.
• B. Pronator teres only.
• C. Pronator quadratus only.
• D. Supinator and pronator teres.

Answer: (A)

Forearm pronation is produced by two muscles that rotate the radius around the ulna: the pronator teres and the pronator quadratus. Pronator teres crosses the elbow and is active when the forearm is flexed, helping turn the palm downward as the radius twists over the ulna. Pronator quadratus sits at the distal forearm, between the radius and ulna, and provides the primary, steady pronation by pulling the distal radius over the ulna and stabilizing the distal radioulnar joint during movement. The muscle that powers supination, the supinator, does the opposite motion, so it isn’t involved in pronation. Together, the pronator teres and pronator quadratus explain how forearm pronation occurs.

Forearm pronation is produced by two muscles that rotate the radius around the ulna: the pronator teres and the pronator quadratus. Pronator teres crosses the elbow and is active when the forearm is flexed, helping turn the palm downward as the radius twists over the ulna. Pronator quadratus sits at the distal forearm, between the radius and ulna, and provides the primary, steady pronation by pulling the distal radius over the ulna and stabilizing the distal radioulnar joint during movement. The muscle that powers supination, the supinator, does the opposite motion, so it isn’t involved in pronation. Together, the pronator teres and pronator quadratus explain how forearm pronation occurs.