Full Lungs Description [Continued from above] . . . Anatomy of
the Lungs The pleura are double-layered serous membranes that
surround each lung. Attached to the wall of the thoracic cavity,
the parietal pleura forms the outer layer of the membrane. The
visceral pleura forms the inner layer of the membrane covering
the outside surface of the lungs. Between the parietal and
visceral pleura is the pleural cavity, which creates a hollow
space for the lungs to expand into during inhalation. Serous
fluid secreted by the pleural membranes lubricates the inside of
the pleural cavity to prevent irritation to the lungs during
breathing. Occupying most of the space within the thoracic
cavity, the lungs extend laterally from the heart to the ribs on
both sides of the chest and continue posteriorly toward the
spine. Each soft, spongy lung is roughly cone-shaped with the
superior end of the lung forming the point of the cone and the
inferior end forming the base. The superior end of the lungs
narrows to a rounded tip known