How It All Works

Better known as the collarbone, it connects the shoulder to the rest of the skeleton and acts as a strut. At its lateral (outer) and it forms the acromioclavicular joint. At its medial (inner) end, it forms the sternoclavicular joint.
‍

The glenoid is part of the scapula (shoulder blade) that forms the shoulder joint with the humerus. It is a shallow cup that is deepened by a rum of fibrocartilage called the labrum.
‍

The humerus is the upper arm bone that runs between the elbow and shoulder joint.
‍

The rotator cuff is a highly specialised arrangement of four main tendons in the shoulder which provides an extraordinary range of motion overhead with precise control. The rotator cuff is formed by the tendons of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles.
‍

A bursa is a potential space filled with a film of fluid associated with joints to allow smooth gliding movement between structures around a joint. The subacromial bursa lies between the acromion (point of the shoulder) and the rotator cuff, allowing it to slider smoothly under the acromion when you raise your arm over your head.
‍

Part of the scapula (shoulder blade), the acromion is a projection of bone that curves over the top of the glenohumeral join (shoulder joint). It provides a scaffold for muscle attachment for the deltoid muscle and forms the acromioclavicular joint with the clavicle.
‍

The acromioclavicular joint is formed where the clavicle (collar bone) meets the scapula (shoulder blade) at the acromion. It has a fibrocartilaginous disc that lies within the joint between the bone ends, and acts as a pivot joint which allows the arm to be raised overhead.
‍

The glenohumeral joint is the shoulder joint.  It is formed between the humerus (upper arm bone) and the scapula (shoulder blade).  Its structure allows great range of motion that conversely predisposes it to instability.

The articular capsule is the thin and pliable lining membrane of the joint. In the shoulder, the capsule has thickenings in it that form ligaments (superior, middle and inferior glenohumeral ligaments) that help give stability to the shoulder.