The pleura is the serous membrane that covers the lung and thoracic pleural cavity. The lung sits within the thoracic cavity. The visceral pleura covers the outer surface of the lung parenchyma, and the parietal pleura covers the inner surface of the thoracic cavity, creating a pleural cavity between them. Under normal conditions, the pleural cavity contains only a thin film of liquid that acts as a lubricant, facilitating the sliding of the two surfaces against each other during respiratory movements.

Both outer pleural surfaces are covered by a single layer of flattened mesothelial cells. The connective tissue of the visceral pleura contains arteries and veins that are mostly thought to be part of the bronchial (systemic) circulation, but this is controversial and probably does not account for all of the visceral pleural circulation. Shunts between the systemic and pulmonary arteries and veins occur increasingly with age and chronic disease. In older patients, bronchial arteries in the visceral pleura may be sclerotic and obliterated. In inflammatory conditions, systemic blood vessels may invade the visceral pleura in adhesions between the visceral pleura and chest wall. The visceral pleura has branches of the vagus nerve and sympathetic trunk but does not contain pain nerve fibers. Pleuritic chest pain always originates in the parietal pleura.