what causes arm to come out of socket
They're easy to confuse. But a dislocated shoulder and a separated shoulder are two distinct injuries. Here's the rundown. Dislocated shoulder. In this injury, a fall or blow causes the top of your arm bone to pop out of the shoulder socket. Unlike a lot of joints in your body -- your elbow, for instance -- the shoulder is incredibly mobile. You can twist and move your upper arm in almost any direction. But there's a price for this ease of movement.