The top of each lung (called the apex) extends into the lowest part of the neck, just above the level of the first rib. The bottom, or base, of each lung extends down to the diaphragm, which is the major breathing-associated muscle that separates the chest from the abdominal cavity.natomy of the Respiratory System. The lungs are the body's major organs of breathing (respiration). The lungs are located on each side of the chest within the rib cage. They are separated by the heart and other contents of the mediastinum—the tissues and organs of the middle chest (e.g., large blood vessels, windpipe).