NCIt definition : 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. This is the deltoid on the left side of the body.;