The shoulder positions the hand in space and demonstrates a wider and more varied range of movements than any other structure. Movement at three joints and a mobile base in the scapula allows the arm to move through it's full range.
The clavicle moves forward and backward, up and down, and rotates on it's own axis. Rotation accommodates scapula movement at the outer ranges of abduction while the larger movements position the shoulder at the lateral end of the pectoral girdle.