The origin of the deltoid muscle is identical to the insertion of which muscle?

• A. Trapezius
• B. Latissimus Dorsi
• C. Teres Major
• D. Pectoralis Major

Answer: (A)

Understanding where a muscle starts (origin) and where it ends (insertion) helps you see how muscles relate and coordinate. The deltoid originates from the lateral third of the clavicle, plus the acromion and spine of the scapula, and it inserts on the deltoid tuberosity of the humerus. The lateral third of the clavicle is exactly where the trapezius inserts. So the origin of the deltoid lines up with the insertion of the trapezius, making trapezius the best match.

The other muscles attach to different sites: latissimus dorsi and teres major insert on the humerus (intertubercular groove), and pectoralis major also inserts there, not on the clavicle.