If the pleural cavity is breached from the outside, as by a bullet wound or knife wound, a pneumothorax, or air in the cavity, may result. If the volume of air is significant, one or both lungs may collapse, which requires immediate medical attention.
Illustration of Heart in Thoracic Cavity
Illustration of Heart Position Relative to the Rib Cage
^Eskandarlou M, Moaddab AH. Chest wall necrosis and empyema resulting from attempting suicide by injection of petroleum into the pleural cavity. Emerg Med J. 2010 Aug;27(8):616-8. doi: 10.1136/emj.2009.073486. Epub 2010 Jun 17.