In human anatomy, the pleural cavity is the potential space between the two pleura (visceral and parietal) of the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered membrane structure. The thin space between the two pleural layers is known as the pleural cavity and normally contains a small amount of pleural fluid. The outer pleura is attached to the chest wall. The inner pleura covers the lungs and adjoining structures, via.