What membrane covers the lungs?

The pleura is the membrane that covers the lungs, providing a protective layer as well as assisting in the mechanics of respiration. It consists of two main layers: the visceral pleura, which tightly adheres to the lung surface, and the parietal pleura, which lines the chest wall and diaphragm. The pleural space between these layers contains a small amount of pleural fluid, which facilitates smooth movement of the lungs during breathing and helps prevent friction between the lung surface and the thoracic cavity.

In contrast, the pericardium is a membrane surrounding the heart, which is distinctly different from the role of the pleura. The periosteum is a dense layer of vascular connective tissue that closely envelops the bones; it does not interact with the lungs at all. Symphysis refers to a type of joint where two bones are joined by fibrocartilage, such as in the pubic symphysis, and is not related to the membranes covering the lungs. Therefore, the pleura is specifically designated for lung coverage and functionality.