The scapula and clavicle are usually referred to as the shoulder girdle, but do they really comprise a “girdle”? In this free Digital COMT video, I make the case that the shoulder girdle would be better termed the shoulder corset. This video plus 100s more are available on DCOMT.
Another reason for shoulder impingement syndrome to occur is insufficient elevation of the clavicle. Most of scapular upward rotation is actually caused by elevation of the clavicle at the sternoclavicular joint, so if clavicular elevation is prevented for any reason, shoulder impingement syndrome can occur.
The shoulder girdle is probably better described as a shoulder corset. This Digital COMT by Dr. Joe Muscolino video describes why.