1). Anatomy of Frontal PA Chest X-Ray
First, it is important that you understand the basic image that we are looking at. We are looking at a frontal view of the chest or the thoracic cavity, which consists of the heart in the middle, the spine in the back, the rib cage with the individual ribs forming an encasement surrounding the lungs, and the diaphragms at the bottom which, like bellows, helps the lungs expand and contract. The left-most image shows the anatomy of the thorax or chest and its cavity, which is gradually stripped down to give the right-most image, which is an outline of the anatomy of the chest that we need to understand - that is the heart in the center, the diaphragms or muscles that act like bellows at the bottom, the chest walls on the periphery and the lungs in between the heart and the chest walls.