Final answer:
Superior rotation and inferior rotation are movements of the scapula during upper limb abduction and adduction, respectively. Gravity can help minimize scapular adduction by causing the glenoid cavity to move downward.
Step-by-step explanation:
Superior rotation and inferior rotation are movements of the scapula that occur during upper limb abduction and adduction, respectively. During superior rotation, the glenoid cavity of the scapula moves upward as the medial end of the scapular spine moves downward, allowing for full abduction of the upper limb.
On the other hand, during inferior rotation, the glenoid cavity moves downward with upward movement of the medial end of the scapular spine. Gravity can minimize scapular adduction by causing the glenoid cavity to move in a downward direction, counteracting the adduction movement and helping to maintain arm position.