What lines the inner wall of the thoracic cavity?

• A. Visceral pleura
• B. Parietal pleura
• C. Diaphragm
• D. Chest wall

Answer: (B)

The inner wall of the thoracic cavity is lined by the parietal pleura. This layer is a serous membrane that adheres to the inner surface of the thoracic wall and also covers the diaphragm. It plays a critical role in the respiratory system by providing a smooth, lubricated surface that allows the lungs to expand and contract without friction during breathing. The parietal pleura is connected to the visceral pleura, which covers the lungs themselves, but it is the parietal layer that is in direct contact with the thoracic cavity wall. This anatomical arrangement is essential for maintaining the pressure gradients necessary for lung inflation and deflation.