The four muscles that make up your rotator cuff are responsible for shoulder movements and maintaining shoulder joint stability. And they can hurt like crazy when you mess them up.
The rotator cuff (RC) describes a group of muscles in the shoulder that connects your upper arm (humerus bone) to your shoulder blade (scapula) and the supporting tendons that act to stabilize the shoulder. The four muscles of the rotator cuff are the Teres minor, Infraspinatus, Supraspinatus, and Subscapularis.
The set of muscles gets its name from the shape formed by the muscles as they attach to the humerus–it looks like a cuff on your shirtsleeve.