turning the head to look over the shoulder is what movement

This is a somewhat rare condition of the shoulder seen in two groups of patients. What is superior migration of the shoulder? It is important to realize that the shoulder is not unstable (i.e., the ball is not dislocating entirely out of the socket), but that the ball is moving out of the center of the socket enough to affect motion. When the ball is not completely in the center of the socket, it is called migration. If the ball does not stay in the center of the socket, the ball does not rotate correctly and the arm does not move as well. The center of the ball stays fairly close to the center of the socket in the normal situation. For the arm to move, the ball has to be in a position that is nearly in the middle of the socket. When the arm moves, the ball rotates on the socket as the arm is rotated or lifted up. When the muscle contracts, it pulls on the tendon, which in turn pulls on the bone, causing it to move. These tendons in turn attach around the ball, forming a cuff of tendons in the front, back and top of the ball. The rotator cuff muscles begin on the shoulder blade and as they get close to the joint they turn into tendons. The ligaments are like ropes that go from the socket to the ball and are essentially tethers that keep the ball from rolling out of the socket (i.e., keep the ball on the dinner plate). The ball is held into the socket by several things, including the muscles, the ligaments, the labrum and the rotator cuff. The ball is much larger than the socket, and some say that a good analogy is that the humeral head on the socket is like a beach ball on a dinner plate. The socket is part of the shoulder blade and is flat.

The ball is the humeral head that is at the end of the humerus or arm bone.

Turning the head to look over the shoulder is what movement