Which actions describe the trapezius muscle?

Which actions describe the trapezius muscle?

• A. Elevates, retracts and rotates the scapula
• B. Depresses and protracts the scapula
• C. Flexes the elbow
• D. Abducts the arm

Answer: (A)

The key idea is how the trapezius moves the shoulder blade. The muscle has upper, middle, and lower fibers that together affect the scapula: the upper fibers lift it (elevation), the middle fibers pull it toward the spine (retraction), and the combined action with the lower fibers causes upward rotation of the scapula. Taken together, elevating, retracting, and rotating the scapula describes the trapezius' action pattern, making that option the best match. Other options describe actions not performed by the trapezius. Protraction is mainly done by the serratus anterior, and while the trapezius can depress the scapula with its lower fibers, it does not protract. Flexing the elbow is the job of forearm muscles like the biceps or brachialis, not the trapezius. Abducting the arm is primarily the deltoid and supraspinatus, with the trapezius assisting scapular rotation to allow abduction but not directly abducting the arm itself.

The key idea is how the trapezius moves the shoulder blade. The muscle has upper, middle, and lower fibers that together affect the scapula: the upper fibers lift it (elevation), the middle fibers pull it toward the spine (retraction), and the combined action with the lower fibers causes upward rotation of the scapula. Taken together, elevating, retracting, and rotating the scapula describes the trapezius' action pattern, making that option the best match.

Other options describe actions not performed by the trapezius. Protraction is mainly done by the serratus anterior, and while the trapezius can depress the scapula with its lower fibers, it does not protract. Flexing the elbow is the job of forearm muscles like the biceps or brachialis, not the trapezius. Abducting the arm is primarily the deltoid and supraspinatus, with the trapezius assisting scapular rotation to allow abduction but not directly abducting the arm itself.