Here are some of the normal mediastinal contours often seen on chest X-rays
These contours are created by difference in density of anatomical structures of the mediastinum and adjacent tissues
Not all of these contours are present on all normal chest X-rays and their visibility depends on technical factors
Abnormality of these contours may help establish the presence and determine the location of pathological processes of the mediastinum or adjacent structures
If one of these contours is obscured, then an abnormality is likely to be located next to the structure that the contour represents