Which of the following is not an external rotator of the glenohumeral joint?

The latissimus dorsi is not considered an external rotator of the glenohumeral joint. This muscle primarily acts to adduct, extend, and internally rotate the humerus. While it does play a significant role in shoulder movements, its primary functions do not include external rotation.

In contrast, the teres minor and infraspinatus are both key external rotators of the shoulder joint, as they are part of the rotator cuff muscles specifically designed to facilitate that movement. The supraspinatus, although primarily known for initiating arm abduction, can also aid in stabilizing the shoulder and has a minor role in external rotation. Thus, the inclusion of the latissimus dorsi as an external rotator is incorrect due to its primary muscle actions that differ from those of the other options presented.