Which term is the primary shoulder muscle responsible for lifting the arm away from the body?

Which term is the primary shoulder muscle responsible for lifting the arm away from the body?

• A. Deltoid
• B. Pectoralis major
• C. Rectus abdominus
• D. Quadriceps femoris

Answer: (A)

Lateral shoulder abduction is produced mainly by the deltoid muscle. The deltoid covers the shoulder joint and, especially its middle fibers, contracts to lift the arm away from the body. While a rotator cuff muscle called the supraspinatus helps start the movement in a very small initial range, the deltoid does the majority of the lifting as the arm rises. The other options aren’t involved in this action: the pectoralis major tends to bring the arm toward the midline and flex the shoulder, the rectus abdominis is a trunk flexor, and the quadriceps femoris extends the knee. So the deltoid is the best answer because it’s the primary muscle responsible for abducting the arm at the shoulder.

Lateral shoulder abduction is produced mainly by the deltoid muscle. The deltoid covers the shoulder joint and, especially its middle fibers, contracts to lift the arm away from the body. While a rotator cuff muscle called the supraspinatus helps start the movement in a very small initial range, the deltoid does the majority of the lifting as the arm rises. The other options aren’t involved in this action: the pectoralis major tends to bring the arm toward the midline and flex the shoulder, the rectus abdominis is a trunk flexor, and the quadriceps femoris extends the knee. So the deltoid is the best answer because it’s the primary muscle responsible for abducting the arm at the shoulder.