The deltoid muscle is a rounded, triangular muscle located on the uppermost part of the arm and the top of the shoulder. which is shaped like an equilateral triangle . It comprises 3 distinct portions each of which produces a different movement of the glenohumeral joint, The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle'. we can see Muscles as anterior deltoid and posterior deltoid as it covers the whole shoulder from above. lateral deltoid is the lateral view of the shoulder. Like many other muscles, the deltoid can be sore for a variety of reasons, including overuse and tendon injuries. the common word for that is deltoid muscle pain. DELTOID ORIGIN: The deltoid has three origins : the lateral end of the clavicle, the acromion of the scapula at the top of the shoulder, and the spine of the scapula. DELTOID INSERTION: deltoid tuberosity of humerus. DELTOID Mu