Which muscles are the prime movers for Forearm Pronation?

Which muscles are the prime movers for Forearm Pronation?

• A. Supinator
• B. Brachioradialis
• C. Pronator teres and Pronator quadratus
• D. Flexor carpi radialis

Answer: (C)

Forearm pronation is produced by rotating the radius over the ulna. The prime movers are the pronator teres and pronator quadratus. Pronator teres, with humeral and ulnar heads, crosses the forearm and twists the radius to bring the palm downward, especially effective when the elbow is flexed. Pronator quadratus sits deep near the distal forearm; its contraction pulls the distal radius across the ulna, driving the rotation and stabilizing the distal radioulnar joint. The other muscles listed don’t prime-pronate: the supinator rotates the radius in the opposite direction (supination); brachioradialis mainly flexes the elbow and only lightly contributes to pronation when the forearm is in a neutral position; flexor carpi radialis acts on the wrist, not the forearm’s rotation.

Forearm pronation is produced by rotating the radius over the ulna. The prime movers are the pronator teres and pronator quadratus. Pronator teres, with humeral and ulnar heads, crosses the forearm and twists the radius to bring the palm downward, especially effective when the elbow is flexed. Pronator quadratus sits deep near the distal forearm; its contraction pulls the distal radius across the ulna, driving the rotation and stabilizing the distal radioulnar joint. The other muscles listed don’t prime-pronate: the supinator rotates the radius in the opposite direction (supination); brachioradialis mainly flexes the elbow and only lightly contributes to pronation when the forearm is in a neutral position; flexor carpi radialis acts on the wrist, not the forearm’s rotation.