Which muscle has its insertion on the acromion?

Which muscle has its insertion on the acromion?

• A. Latissimus dorsi
• B. Levator scapulae
• C. Trapezius (middle fibers)
• D. Rhomboid major

Answer: (C)

Inserting on the acromion tells you which scapular muscle is directly anchoring to that bony point and how it moves the shoulder blade. The acromion is the lateral projection of the scapula, and the trapezius has a portion whose fibers attach there. Those middle fibers pull the scapula medially, retracting it toward the spine, which is the primary effect of attaching to the acromion. The other muscles don’t attach to the acromion: latissimus dorsi ends in the intertubercular groove of the humerus, driving arm movements rather than scapular positioning; levator scapulae attaches to the superior angle and medial border to elevate the scapula; rhomboid major attaches along the medial border to retract the scapula but does not reach the acromion. So, the muscle with insertion on the acromion is the trapezius (middle fibers), making it the correct choice.

Inserting on the acromion tells you which scapular muscle is directly anchoring to that bony point and how it moves the shoulder blade. The acromion is the lateral projection of the scapula, and the trapezius has a portion whose fibers attach there. Those middle fibers pull the scapula medially, retracting it toward the spine, which is the primary effect of attaching to the acromion.

The other muscles don’t attach to the acromion: latissimus dorsi ends in the intertubercular groove of the humerus, driving arm movements rather than scapular positioning; levator scapulae attaches to the superior angle and medial border to elevate the scapula; rhomboid major attaches along the medial border to retract the scapula but does not reach the acromion. So, the muscle with insertion on the acromion is the trapezius (middle fibers), making it the correct choice.