What actions does the infraspinatus perform?

The infraspinatus is one of the four rotator cuff muscles which primarily performs two key actions: shoulder lateral rotation and stabilization of the humeral head in the glenoid cavity of the shoulder joint.

When the shoulder is laterally rotated, the infraspinatus works in conjunction with other muscles, such as the teres minor and the supraspinatus, to ensure the smooth movement of the arm away from the body. This action is crucial in various activities that require arm mobility and strength, particularly overhead movements.

Additionally, the stabilization of the humeral head is critical for maintaining joint integrity during various motions. This means that while the arm is lifted or rotated, the infraspinatus helps keep the humeral head seated properly in the glenoid cavity, preventing dislocations and enhancing joint stability.

Therefore, the choice that accurately describes the functions of the infraspinatus aligns perfectly with its anatomical role and physiological actions in the shoulder complex.