The Deltoid is a three-headed muscle that caps the shoulder. The three heads of the Deltoid are the Anterior, Lateral, and Posterior. All three Deltoid heads attach to the humerus (bone from shoulder to elbow). The Anterior and Lateral heads originate on the collar bone, while the Posterior head originates on the scapula (shoulder blade).
The trapezius muscle is a large, superficial muscle that spans the neck, shoulders and back.