The rotator cuff (will reference as RC from here on out) is a group of 4 muscles and their associated tendons that span the shoulder joint, or more anatomically speaking, the glenohumeral joint.

These muscles are: the supraspinatus, infraspinatus, teres minor, and subscapularis.

The RC is extremely vital to dynamic shoulder joint stability, as they are the only muscles that directly span the glenohumeral joint. While our bigger muscles, like our deltoids, lats, and pectorals control gross movements around the shoulder, the RC acts to stabilize the glenohumeral joint during these movements.

[…]