What is the distinguishing feature of the visceral pleura?

The visceral pleura is a critical anatomical structure that covers the lungs themselves. It forms the external surface of the lung, tightly adhering to the lung tissues. This is significant because the visceral pleura is essential for providing a smooth, frictionless surface that allows for the expansion and contraction of the lungs during breathing.

The visceral pleura contrasts with the parietal pleura, which is responsible for lining the inner surface of the thoracic cavity. This distinction is crucial for understanding how pleural cavities function and how they help facilitate respiration.

In addition, the visceral pleura is involved in the production of pleural fluid, which is important for reducing friction between the lungs and the thoracic wall, but the main feature is its direct association with the lung surface. This positioning allows it to play an essential role in respiratory mechanics without being the structure that forms the outer layer of the lung or lines the rib cage.