26.9 : 肺の胸膜

The pleura or pleural membrane is a double-layered serous membrane enclosing the lungs.

The right and left lungs are enveloped by their respective pleurae, separated by the mediastinum.

The outer parietal pleura contacts the thoracic wall, the mediastinum, and the diaphragm, while the inner visceral layer covers the external lung surface.

The pleural cavity between these layers is filled with a lubricating liquid called the pleural fluid.

This fluid reduces the friction between the layers during respiration and creates surface tension that helps the lungs adhere to the thoracic wall.

Additionally, the cohesive property of the pleural fluid enables lung expansion with the thoracic wall during breathing, helping the lungs to fill with air.

The pleurae also provide a boundary between the moving heart and lungs, preventing potential disruption in their movement and limiting the spread of infections.

Pleurisy is an inflammation of the pleurae, often caused by pneumonia, which leads to roughened surfaces and stabbing pain during breathing.