Which actions characterize the latissimus dorsi?

• A. Extension, adduction and medial rotation of the humerus
• B. Flexion and abduction of the shoulder
• C. Protraction of scapula
• D. Elevation of clavicle

Answer: (A)

The main actions of the latissimus dorsi are extension, adduction, and medial (internal) rotation of the humerus at the shoulder joint. Because this muscle originates from the lower spine and pelvis and inserts into the intertubercular groove of the humerus, its pull draws the arm downward and backward (extending it), brings it toward the midline (adduction), and rotates the arm inward (medial rotation). It does not flex or abduct the arm, and it doesn’t protract the scapula or elevate the clavicle, so those options don’t describe its primary actions.