Answer:
The Scapulothoracic (ST) “joint” is not a true anatomic joint as it has none of the usual joint characteristics (union by fibrous, cartilaginous, or synovial tissues).
It is an articulation of the scapula with the thorax which depends on the integrity of the anatomic Acromioclavicular (AC) and Sternoclavicular (SC) joints.
The SC and AC joints are interdependent with the ST joint because the scapula is attached by its acromion process to the lateral end of the clavicle & through the AC joint; the clavicle, in turn, is attached to the axial skeleton at the manubrium of the sternum through the SC joint.
Any movement of the scapula on the thorax must result in movement at either the AC joint, the SC joint, or both; that is, the functional ST joint is part of a true closed chain with the AC and SC joints and the thorax.
Explanation:
