Final answer:
Internal rotation of the shoulder and proximal humerus profiles the lesser tubercle medially, which is necessary for certain medical imaging techniques.
Step-by-step explanation:
The position of the shoulder and proximal humerus that projects the lesser tubercle in profile medially is internal rotation. In internal rotation, the movement of the arm at the shoulder joint brings the anterior surface of the limb toward the midline of the body. This position allows the lesser tubercle of the humerus to become more prominent medially. Conversely, external rotation would project the lesser tubercle laterally and is not the correct position to medially profile the lesser tubercle. It's important to note that the greater tubercle is found on the lateral side of the proximal humerus while the lesser tubercle is found on the anterior aspect. During internal rotation, the lesser tubercle moves medially and becomes more visible on imaging such as an x-ray.