Gross Anatomy Block 2 Practice Test

Which muscle is in the posterior compartment deep layer and functions to supinate the forearm?

Supinator Extensor indicis Abductor pollicis longus Extensor pollicis brevis

Correct Answer:

Supinator

Explanation:

Supination of the forearm is produced primarily by a muscle in the posterior compartment’s deep layer. This muscle wraps around the proximal radius, pulling the radius to rotate around the ulna and turn the palm upward. It originates from the ulna and humeral region near the elbow and inserts on the lateral surface of the proximal radius. Its action is specifically to rotate the forearm, rather than extend fingers or move the thumb, making it the key muscle for supination. It is innervated by the deep branch of the radial nerve (posterior interosseous nerve). The other muscles listed mainly extend the fingers or the thumb and do not serve as primary supinators.

Access more questions from this quiz

Continue to Gross Anatomy Block 2 Practice Test for more practice questions and the full quiz experience.

Access More Questions