What is the deltoid muscle and what does it do?
The deltoid muscle is a large muscle that encompasses the shoulder joint. The deltoid is divided into three different portions, or heads, the anterior (front), middle, and posterior (back) portions of the deltoid. The deltoid originates on the lateral aspect of the acromion and clavicle and then inserts on the lateral aspect of the humerus. Its major action is to abduct the arm (lift the arm out to the side of the body) as well as assist in forward elevation (lifting the arm out in front of the body). The deltoid is a very powerful muscle and is needed for all types of athletic endeavors.
