The deltoid is a triangular-shaped muscle of the upper arm. It has three “heads,” hence the name. On the anterior (front) side of the body, it begins on the clavicle. The lateral (side) head begins on the acromial process, or the point where the end of the clavicle meets the top of the humerus. The posterior (back) head begins on the spine of the scapula, or shoulder blade.
Nearly every massage style includes work on the deltoid. Deep tissue and trigger point therapies are often used for intense, focused attention to each head of the deltoid.