Which muscle of the pectoral girdle raises the arms and pulls the shoulders downward?

• A. Pectoralis major
• B. Deltoid
• C. Serratus anterior
• D. Trapezius

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the anatomy of the pectoral girdle, which includes muscles that connect the upper limb to the axial skeleton and facilitate movement of the arms and shoulders.
2. Step 2: Review the function of the trapezius muscle. The trapezius is a large, triangular muscle located in the upper back and neck region. It is responsible for several actions, including raising the arms, pulling the shoulders downward, and stabilizing the scapula.
3. Step 3: Compare the trapezius muscle's function with the other options provided: Pectoralis major (responsible for flexion, adduction, and medial rotation of the arm), Deltoid (responsible for abduction of the arm), and Serratus anterior (responsible for protraction and upward rotation of the scapula). None of these muscles perform the specific actions of raising the arms and pulling the shoulders downward.
4. Step 4: Confirm that the trapezius muscle is the correct answer based on its anatomical location and function, as it uniquely performs the actions described in the question.
5. Step 5: To solidify understanding, visualize the trapezius muscle's role in movements such as shrugging the shoulders or pulling them downward during activities like carrying heavy objects.