Term
Deltoid
Meaning
The deltoid is the rounded muscle that caps the shoulder, wrapping from the collarbone over the tip of the shoulder to the ridge of the shoulder blade. OpenStax Anatomy and Physiology describes it as a muscle that lifts the arm at the shoulder. Artists draw it as a three-sided cap sitting on top of the upper arm and tapering to a point on the outer arm, which makes the shoulder feel solid instead of flat. Its outline changes when the arm is raised. See also: Trapezius, Acromion, Clavicle and the guide "Major Muscle Groups for Artists: Shapes Over Names".