Rotator Cuff Injury explained by Scott Curtis DO, Princeton Spine & Joint Center
"As a sports medicine doctor, one of the most common complaints that I'll see from patients is shoulder pain. And one of the most common reasons for one to develop shoulder pain is because of a rotator cuff injury or tear. The rotator cuff is a group of four muscles that hold the shoulder together. So in this model, the collarbone sits in the front, the shoulder blade sits in the back, the collarbone and shoulder blade form to meet the AC joint. And underneath that is where the arm humorous head sits in the arm socket. The arm socket ball complex is held together by four muscles called your rotator cuff. And these muscles help act as kind of ropes and pulleys to allow your arm to do all the activities that you do overhead, whether it's throwing a baseball or hitting a tennis ball, or even just reaching up to get something out of the counter.

~ Scott Curtis, D.O.

For the full information bout rotator cuff injury, watch this video