Which muscle laterally rotates the forearm?Multiple choice question.supinatorinfraspinatusdeltoidpronator quadratus

To determine which muscle laterally rotates the forearm from the given options, we can analyze each muscle's primary function:

1. Supinator: This muscle primarily helps in supination (rotation of the forearm so the palm faces up) but does not laterally rotate the forearm in the context of external rotation.

2. Infraspinatus: This muscle is one of the rotator cuff muscles and is responsible for laterally (externally) rotating the humerus at the shoulder joint. However, it does not directly rotate the forearm.

3. Deltoid: The deltoid muscle primarily assists in shoulder abduction, flexion, and extension. While it has different fibers that can aid in rotation, it does not specifically fulfill the function of laterally rotating the forearm.

4. Pronator Quadratus: This muscle is involved in pronation (rotation of the forearm so the palm faces down), opposing lateral rotation.

Final Answer

The correct answer is infraspinatus. It is the muscle that laterally rotates the shoulder, which indirectly affects the arm's position, but none directly laterally rotate the forearm in the same manner as they do for the shoulder.