Which joint is NOT one of the primary joints found in the shoulder?

The correct answer identifies the proximal radioulnar joint as not being one of the primary joints found in the shoulder. The shoulder complex is primarily comprised of the acromioclavicular, sternoclavicular, and glenohumeral joints.

The acromioclavicular joint connects the acromion of the scapula to the clavicle, playing a key role in shoulder mobility and stability. The sternoclavicular joint attaches the sternum to the clavicle, serving as the only bony connection between the upper limb and the axial skeleton and facilitating various movements of the shoulder girdle. The glenohumeral joint, commonly known as the shoulder joint, is where the head of the humerus fits into the glenoid cavity of the scapula, allowing for a wide range of motion in the arm.

In contrast, the proximal radioulnar joint is involved in the rotation of the forearm and is located near the elbow, connecting the radius and ulna bones, rather than participating in shoulder mechanics. Thus, it does not belong to the group of primary joints associated with shoulder movement.