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.
This muscle is responsible for most of the motion of the upper arm. It is one of the most used muscles in the body. The lateral section of the deltoid moves the upper arm away from the body. The anterior section flexes the arm, as well as horizontally flexing the arm across the chest. Posteriorially, the muscle rotates the upper arm to the outside.
Deltoid Muscle Trigger Points and Pain
Trigger points are very common in the deltoid. Most of the time, they are formed in the anterior and posterior sections. In both instances, they refer pain down the outside of the arm all the way to the elbow.
The deltoid is prone to overuse and micro-tears that can lead to the formation of scar tissue. These tears are common near the attachment points on each head of the muscle.
Massage for Deltoid
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.