The intrapleural or pleural space is the fluid-filled space in between the parietal and visceral layers of the pleura. In normal conditions it contains only a small amount of serous pleural fluid.
Rarely there may be anomalous communication of the pleural spaces anteriorly.
The pleural space can also be affected by a number of malignancies:
When air leaks into the pleural space, a life threatening pneumothorax may develop.