Step by Step / Updated 03-27-2016
When you move your arms in virtually any direction — up, down, backward, forward, sideways, diagonally, or in circles — your shoulders are in charge or at least involved. The ingenious design of your shoulder joint makes the shoulders one of the most mobile, versatile muscle groups in your body. Unfortunately, their amazing capacity for movement also makes the shoulders, along with a nearby muscle group called the rotator cuff, particularly vulnerable to injury.