Anatomy of the Human Shoulder Joint
The shoulder joint is the junction between the chest and the upper extremity. Two joints are at the shoulder. The glenohumeral joint is the ball-and-socket junction of the top of the arm bone, and the socket of the shoulder blade. A second joint in the shoulder is the junction of the collar bone with the shoulder blade, called the acromioclavicular joint. Most shoulder motion occurs at the ball-and-socket glenohumeral joint, but for full motion of the shoulder, the acromioclavicular joint must also be functioning normally.
Source: Verywell Health
