Shoulder Instability: The shoulder is a ‘ball and socket’ type joint made up by the head of the upper arm bone (‘humerus) and the shoulder blade cavity (‘glenoid). In an unstable or ‘loose’ shoulder, the head of the humerus slips in and out of the shoulder glenoid (ball slips in and out of the socket). This could be caused by injuries to a number of structures including the labrum, glenohumeral ligaments, joint capsule or rotator cuff. For additional information, please review the dislocated shoulder and shoulder instability section on this website.
Return to Sports Medicine Terminology
