The rotator cuff comprises of a set of four muscles that serve to stabilize the shoulder, including the Infraspinatus, Supraspinatus, Teres Minor, and Subscapularis. They connect the scapula to the humerus.
In a rotator cuff tear, the tendons of these muscles become torn where they attach onto the humerus bone, due to impact, or excessive stress on the shoulder, leading to pain and limited mobility of the region.