Shoulder joints and ligaments

The movement of the shoulder is permitted by three distinct joints:

acromioclavicular (AC) joint formed by the acromion, which is the postero-anterior bone of the scapula and the clavicle bone

sternoclavicular (SC) joint situated at the centre of the upper chest right under the throat where both clavicle bones meet (breast bone)

glenohumeral joint is the main joint of the shoulder consisting of the humeral head inserting in the glenoid.