Delts

Delts is a common abbreviation for the deltoid muscles, which are the muscles forming the rounded contour of the shoulder. These muscles are crucial for shoulder movement and stability. The deltoid is a large, triangular muscle located at the very top of the arm and the side of the shoulder. It is comprised of three distinct sections, or heads: the anterior (front) deltoid, the lateral (side) deltoid, and the posterior (rear) deltoid. Each head originates from a different part of the scapula (shoulder blade) and clavicle (collarbone) and inserts onto the humerus (upper arm bone).

The anterior deltoid is primarily responsible for flexing the arm at the shoulder, meaning it helps lift the arm forward and slightly upwards. It also assists in medial rotation of the arm. The lateral deltoid's main function is abduction of the arm, which is the movement of lifting the arm away from the body to the side. The posterior deltoid is involved in extending the arm at the shoulder, moving it backward, and also contributes to lateral rotation. Together, these three heads allow for a wide range of motion at the shoulder joint, including flexion, extension, abduction, adduction, rotation, and circumduction. Injuries to the deltoid muscles can affect daily activities that involve arm movement.