The shoulder girdle can perform five distinct movements.
The shoulder girdle, comprised of the clavicle and scapula, is crucial for upper limb mobility. These movements are not driven by a single joint, but rather a coordinated action primarily involving the scapula gliding across the rib cage. The five movements are:
- Elevation: Moving the scapula upward (e.g., shrugging the shoulders).
- Depression: Moving the scapula downward.
- Protraction (Abduction): Moving the scapula away from the spine (e.g., rounding the shoulders forward).
- Retraction (Adduction): Moving the scapula towards the spine, squeezing the shoulder blades together.
- Superior and Inferior Rotation: The scapula rotates upward or downward, affecting the glenoid cavity's (where the humerus connects) orientation. Superior rotation occurs when the inferior angle moves away from the midline, while inferior rotation occurs when it moves towards the midline. This movement is essential for raising the arm overhead.
These movements allow for a wide range of arm positions and are essential for many daily activities.
