Pleura that reflects from the medial wall and onto the surface of the lung is visceral pleura (Fig. 3.37), which adheres to and covers the lung.
Each pleural cavity is the potential space enclosed between the visceral and parietal pleurae. They normally contain only a very thin layer of serous fluid. As a result, the surface of the lung, which is covered by visceral pleura, directly opposes and freely slides over the parietal pleura attached to the wall.