Which muscle is responsible for abducting the shoulder?

The deltoid muscle is primarily responsible for abducting the shoulder. It is a large, triangular muscle that forms the rounded contour of the shoulder. The deltoid has three distinct parts—anterior, lateral, and posterior—that contribute to different movements of the shoulder joint. The lateral portion of the deltoid is particularly important for shoulder abduction, which occurs when the upper arm moves away from the body.

Understanding shoulder abduction is essential in physical therapy, as it plays a critical role in many upper limb activities such as lifting arms and reaching overhead. While other muscles, like the supraspinatus, assist in this movement, the deltoid is the primary mover for shoulder abduction, especially when the arm is elevated beyond 15 degrees. The trapezius and latissimus dorsi have other roles, such as stabilization and adduction, respectively, but they do not primarily facilitate the abduction of the shoulder.