Final answer:
The movements of superior rotation and protraction of the scapula are essential for upper limb mobility, with the glenoid cavity moving upwards and the shoulder moving forward respectively. These movements are supported by muscles that stabilize and move the pectoral girdle.
Step-by-step explanation:
The movement accompanying upward rotation and protraction of the shoulder girdle is primarily facilitated by the muscles that position the pectoral girdle. In the case of upward rotation, the glenoid cavity of the scapula moves upwards as the medial end of the scapular spine moves downwards. This movement is critical for upper limb abduction, allowing the shoulder to move above head height without the greater tubercle of the humerus impacting the acromion of the scapula.
When we talk about protraction of the scapula, it refers to the shoulder moving forward. For instance, this would occur when pushing against something or during a throwing motion. Muscles such as the serratus anterior are involved in this forward movement of the shoulder. Both of these movements, superior rotation and protraction, are essential for various arm movements and are supported by different groups of muscles that function to stabilize and move the pectoral girdle.