The subacromial space refers to the space above the shoulder’s glenohumeral joint (ball-and-socket joint) and below the acromion, the top-most bone of the shoulder. Soft tissues, such as the bicep tendon, rotator cuff, and bursa are located in the subacromial space. During certain shoulder movements, the subacromial space becomes smaller, and these soft tissues can become pinched, a condition called shoulder impingement.