The Deltoid Muscles (also known as Deltoids or Delts for short) are a group of triangular muscles which most people would recognize as the shoulder muscles and are located on top of the common shoulder joint for the Scapula, Clavicle and Humerus. As the Deltoid muscles pass up and over the shoulder joints, it forms the rounded shape of the shoulders and upper arm. The Deltoid Muscles originate from their attachment to the Scapula and the Clavicle and the insertion point is halfway down the length of the Humerus.
Three Separate divisions or the Deltoid Muscles
The Deltoid muscles are made up of three different divisions of muscles which take the shape of a triangle hence the name; delta is Greek for triangle. These three different divisions of muscles are mainly responsible for all side lifting movements as well as any movement of the humerus on the scapula, in other words all movements of the arm above the elbow joint. They are as follows;
1.The anterior division, also known as the anterior deltoid, is located on the front of your shoulder just above the chest muscles.
2. The middle division, also known as the medial deltoid, is located on the outside aspect of your shoulder.
3.The posterior division, also known as the posterior deltoid, is located on the backside of the shoulder joint.
Typically, there is a combination of these divisions which work together to produce specific movements. The anterior and middle divisions of the Deltoid muscles (in conjunction with other muscle groups) are predominantly responsible for pressing movements and exercises to the front of the body as well as over the head, such as push ups, bench press or shoulder presses. The posterior division of the Deltoid muscles (in conjunction with other muscle groups) are responsible for the pulling movements and exercises such as bent-over rows, pull-ups, pull-downs, and movements such as moving the arms from center away from the body.