It is palpable in the deltopectoral groove between the deltoid and pectoralis major muscles. Common injections sites include the deltoid, vastus lateralis, and ventrogluteal muscles. Its synergists are teres minor and the deltoid. The (where the deltoid and pectoral muscles attached) was weakly developed. It originates at the spine of the scapula and inserts at the deltoid ridge. For others, such as the rectus femoris or deltoid muscle, it becomes more complicated. Traditionally, the axillary nerve is thought to only supply the deltoid and teres minor. The deltoid is innervated by the axillary nerve. The anterior deltoid should be recruited as the stabilizer. This is located posteroinferior to the deltoid tuberosity. It is mainly used in throwing, with the deltoid muscle and rotator cuff. It originates at the acromion process and inserts at the deltoid ridge. The arm must be medially rotated for the deltoid to have maximum effect. Usually the echogenicity compared to the deltoid muscle is homogeneous intensified without dorsal echo extinction. The acromiodeltoid is the shortest of the deltoid muscles.