Which muscle also assists scapular upward rotation besides serratus anterior and upper trapezius?

• A. Levator scapulae
• B. Rhomboids
• C. Lower trapezius
• D. Pectoralis minor

Answer: (C)

Upward rotation of the scapula during above-head movements comes from a coordinated force couple. Serratus anterior pulls the medial border of the scapula away from the spine and helps rotate the scapula upward, while the upper trapezius lifts the scapula and contributes to that rotation. The lower fibers of the trapezius add their part by pulling the inferior angle downward and outward, which completes the upward rotation when working together with serratus anterior. This synergy allows the glenoid fossa to face upward as the arm elevates.

The other muscles listed don’t support this upward rotation in the same way: levator scapulae mainly elevates the scapula (and can contribute to downward rotation with certain positions), rhomboids retract and downwardly rotate, and pectoralis minor protracts and downwardly tilts the scapula.