Shoulder​​
​The shoulder is made out of 4 separate articulations; the acromioclavicular joint ("AC" joint), the sternoclavicular ("SC" joint), the scapulothoracic joint and the glenohumeral joint. Most problems we see in the shoulder arise due to disease or injuries to the glenohumeral or AC joints.
The glenohumeral joint is a ball-and-socket joint. The glenoid (socket) and ball (humerus) are covered with articular cartilage allowing a smooth articulation. The joint is surrounded by soft tissues. The labrum is a fibrocartilaginous structure which acts as a bumper and to deepen the socket. The capsule contains a series of ligaments (superior, middle and inferior glenohumeral ligaments) both at the front (anterior) and back (posterior) of the joint
The rotator cuff is a series of 4 muscles that surround the glenohumeral joint. These act to dynamically compress the humerus into the glenoid allowing for a stable range of motion. Each muscle has a different action. The supraspinatus initiates abduction (moving arm out to the side). The infraspinatus and teres minor act to rotate the arm externally. The subscapularis rotates the arm internally. The rotator cuff acts as a dynamic stabiliser of the shoulder.
