The shoulder joint is a ball and socket joint that stretches further than normal. Your shoulder has such an incredible range of motion that you can rotate it in any direction. However, what you sacrifice for having this phenomenal range of motion is joint stability. Over 20% of the adult population has been shown to have some degree of rotator cuff tear. The shoulder joint accommodates the head of the humerus, which has a very large ball that marries with a very small socket. There is nothing that is holding the ball in that socket apart from the surrounding musculature. One can develop a tear in the rotator cuff tendons, if one’s arm is externally rotated and abducted too forcefully. More commonly, one will perform a type of movement repetitively that chronically scrubs the tendons and can lead to long term injury. There are no muscles “in” the rotator cuff but there are muscles that attach to the tendons that make up the rotator cuff. The rotator cuff connects to 4 primary separate muscles (1) Supraspinatus – On top of the shoulder blade (2) Infraspinatus – On the shoulder blade (3) Teres Minor – Side of the shoulder blade and under the arm pit (4)Subscapularis-Beneath the shoulder blade. The tendons from these four muscles converge into the shoulder joint and attach to the ball of the humerus. Two of these tendons rotate externally and two of them rotate internally, collectively, they make up what is called the rotator cuff. Upper body exercises serve to provide strengthening for the surrounding muscles that support the shoulder joint such as pectoralis, trapezius, latissimus dorsi and the rhomboids. All of the muscle groups contribute to the well-being of the shoulder joint by providing both protective shock-absorptive capability and strength.