Which muscle is identified as a shoulder joint external rotator?

The infraspinatus is identified as a shoulder joint external rotator due to its anatomical positioning and function. This muscle is part of the rotator cuff group and is located on the posterior aspect of the shoulder. When the infraspinatus contracts, it pulls the greater tuberosity of the humerus backward and outward, allowing the arm to rotate externally at the shoulder joint.

This characteristic makes it essential for various activities that involve overhead movement and stabilization of the shoulder. In addition to facilitating external rotation, the infraspinatus also contributes to shoulder stability and helps in the overall coordination of shoulder movements during exercises and functional tasks.

In contrast, other muscles such as the teres major and pectoralis major primarily function as internal rotators or have different roles, while the coracobrachialis is involved in flexion and adduction of the arm rather than external rotation.