The correct option is Parietal pleura (outer).
Explanation
The lungs are enclosed by a double-layered serous membrane system called the pleura. These layers protect the lungs and reduce friction during respiration. The space between the two layers is known as the pleural cavity, which is filled with pleural fluid.
Option Analysis
- Parietal pleura (outer) is Correct: The parietal pleura is the outer layer of the pleural membrane. It lines the inner surface of the thoracic cavity (thoracic lining), the upper surface of the diaphragm, and the mediastinum. It is structurally attached to the thoracic wall.
- Visceral pleura (inner) is Incorrect: The visceral pleura is the inner layer that firmly adheres to the surface of the lungs, following their contours and fissures. It is not in direct contact with the thoracic wall.
- Mediastinal pleura is Incorrect: The mediastinal pleura is a specific subdivision of the parietal pleura that covers the mediastinum (the central compartment of the thoracic cavity). While it is part of the outer system, the term "parietal pleura" broadly encompasses the membrane lining the entire thoracic cavity.
- Alveolar pleura is Incorrect: "Alveolar pleura" is not a standard anatomical term. Alveoli are microscopic air sacs within the lung parenchyma and are not lined by a pleural membrane.
Key Takeaway
The Parietal Pleura is the outer membrane lining the thoracic wall, while the Visceral Pleura is the inner membrane covering the lung surface.