Deltoid
deltoid
"The muscle that creates the rounded contour of the shoulder which originates from the lateral third of the clavicle, the superior surface of the acromion process, and the posterior border of the spine of the scapula and inserts on the lateral side of the shaft of the humerus. The deltoid muscle is innervated by the brachial plexus arising from the fifth and sixth cervical nerves and controls abduction, extension, flexion, and rotation of the arm."