What are the inferior lateral corners of the lungs, visible on a PA chest radiograph, called?

The inferior lateral corners of the lungs that are visible on a PA chest radiograph are known as the costophrenic angles. These angles are formed where the diaphragm meets the ribs and are critical reference points in radiographic interpretation. Specifically, they indicate the junction between the pleura and the lateral chest wall, and they are clinically significant when evaluating for fluid accumulation, such as in pleural effusion. When looking at a chest X-ray, a clear and well-defined costophrenic angle is typically a sign of normal lung health, while blunting of these angles can suggest pathology.

The term “cardiac shadows” refers to the silhouette of the heart and structures surrounding it, which do not pertain to the corners of the lungs. The apex of the lungs is the uppermost part, not the lower corners. The base of the lungs refers to the part that sits upon the diaphragm and encompasses more than just the lateral inferior angles. Thus, the context in which "costophrenic angles" is used illustrates its importance in the interpretation of chest radiographs.