Pleura:One of the two membranes around thelungs. These two membranes are called thevisceralandparietalpleurae. The visceralpleuraenvelops the lung, and the parietal pleura lines the innerchestwall. There is normally a small quantity (about 3 to 4 teaspoons) of fluid that is spread thinly between the visceral and parietal pleurae. Thepleuralfluid acts as alubricantbetween the two membranes.
