Question

Which of the following statements about the motions of supination and pronation in the forearm is MOST CORRECT?

A. Muscles with attachments only to the humerus produce these motions.
B. Muscles with attachments to the ulna produce these motions because the ulna rotates around a stationary radius.
C. Muscles with attachments to the wrist carpals produce these motions.
D. Muscles with attachments to the radius produce these motions because the radius rotates around a stationary ulna.

Answer 1

Muscles with attachments to the radius, specifically the pronator teres and the pronator quadratus for pronation, and the supinator for supination, facilitate the movements of supination and pronation. The radius rotates around a stationary ulna during these motions. Option D is correct.

Step-by-step explanation:

The statement about the motions of supination and pronation in the forearm that is most correct is Muscles with attachments to the radius produce these motions because the radius rotates around a stationary ulna. During pronation, the radius rotates over the ulna at the proximal and distal radioulnar joints, causing the two bones to form an X-shape.

The primary muscles involved in pronation are the pronator teres and the pronator quadratus, while supination is primarily facilitated by the supinator muscle. These movements are crucial for the rotation of the forearm and hand, allowing for various daily activities like turning a doorknob or using a spoon.