Which muscle abducts the shoulder?

Which muscle abducts the shoulder?

• A. Pectoralis Major
• B. Latissimus Dorsi
• C. Infraspinatus
• D. Deltoid

Answer: (D)

Abduction of the shoulder means lifting the arm away from the body. The deltoid, especially its middle fibers, is the primary muscle responsible for pulling the arm straight outward to the side across most of the range of motion. The initial small portion of abduction is actually driven by another muscle, but among the options given, the deltoid is the main abductor. The other muscles listed have actions that pull the arm toward the midline (pectoralis major), pull it downward or rotate it inward (latissimus dorsi), or stabilize and rotate the shoulder rather than lift it away (infraspinatus). So the deltoid best fulfills the role of shoulder abduction.

Abduction of the shoulder means lifting the arm away from the body. The deltoid, especially its middle fibers, is the primary muscle responsible for pulling the arm straight outward to the side across most of the range of motion. The initial small portion of abduction is actually driven by another muscle, but among the options given, the deltoid is the main abductor. The other muscles listed have actions that pull the arm toward the midline (pectoralis major), pull it downward or rotate it inward (latissimus dorsi), or stabilize and rotate the shoulder rather than lift it away (infraspinatus). So the deltoid best fulfills the role of shoulder abduction.