Question: which of the muscles listed is not a rotator cuff muscle?
Answer: The supraspinatus is responsible for the first 15 degrees of abduction; the deltoid, an intrinsic muscle of the shoulder that is not a rotator cuff muscle, is responsible for abduction from 15 to 90 degrees. The infraspinatus and teres minor both aid in lateral, or external, rotation of the arm at the shoulder.