The scapulothoracic joint, also known as the scapulothoracic articulation, is not a true synovial joint, but rather the articulation formed by the interaction between the scapula and the posterior rib cage. This articulation is crucial for upper extremity movement.
Understanding the Scapulothoracic Articulation
Instead of possessing the typical joint structures like a capsule and synovial fluid, the scapulothoracic "joint" relies on the gliding motion between:
- The convex surface of the posterior thoracic cage (ribs).
- The concave surface of the anterior scapula.
The scapula, being a flat bone, facilitates this gliding action, primarily through the actions of two key muscles:
- Subscapularis: This muscle sits between the scapula and the rib cage, aiding in smooth movement.
- Serratus Anterior: This muscle connects the scapula to the ribs, playing a vital role in protraction (moving the scapula forward) and upward rotation.
Importance of Scapulothoracic Movement
The scapulothoracic articulation is essential for a full range of pain-free shoulder movement. It allows for:
- Elevation and Depression: Raising and lowering the scapula.
- Protraction and Retraction: Moving the scapula forward and backward.
- Upward and Downward Rotation: Rotating the scapula to allow the arm to be raised overhead.
Dysfunction in this articulation can lead to various shoulder problems, impacting overall upper extremity function.
