Potential space

In anatomy, a potential space is a space between two adjacent structures that are normally pressed together (directly apposed). The pleural space, between the visceral and parietal pleura of the lung, is a potential space. Though it only contains a small amount of fluid normally, it can sometimes accumulate fluid or air that widens the space.[1] The pericardial space is another potential space that may fill with fluid (effusion) in certain disease states (e.g. pericarditis; a large pericardial effusion may result in cardiac tamponade.