The greater tubercle of the humerus is best demonstrated in profile laterally in which projection?

The greater tubercle of the humerus is best demonstrated in profile laterally in the AP external rotation projection. In this projection, the arm is positioned so that the thumb points outward, which brings the greater tubercle into a lateral position relative to the rest of the humeral anatomy. By positioning the shoulder in this manner, radiologists can visualize the greater tubercle distinctly, enhancing its prominence on the image.

In contrast, the other projections either do not position the humerus favorably for lateral visualization of the greater tubercle or obscure it. The AP internal rotation projection turns the arm in the opposite direction, resulting in the greater tubercle being positioned anteriorly, while a lateral projection often captures the entire humerus in profile without highlighting the greater tubercle specifically. An axial projection typically focuses on the joint spaces or other internal structures rather than demonstrating the greater tubercle in a profile view. Thus, the AP external rotation projection provides the optimal angle and visualization needed for this bony landmark.