Abnormal shoulder physiology 2020-09-05T13:42:07Z Anopmalous function of the shoulder. The shoulder is a ball-and-socket joint that is made up of humerus, scapula and clavicle, which are connected by the sternoclavicular joint (SC), the acromioclavicular joint (AC), the glenohumeral joint (GH), and the scapulothoracic joint (ST). The GH, AC and SC joints link the upper extremity to the axial skeleton at the thorax and enable movement at the shoulder joint: flexion, extension, and rotation of the arm. Abnormal joint physiology