The pleural cavity is an area which surrounds the lung. Each lung is inside an isolated pleural cavity, with the lungs forming inside the cavity during fetal development. This space inside the body is formed between the parietal and visceral pleura which line the lungs and body cavity. It allows room for the lungs to expand and contract, and is designed to make it easy for the lungs to inflate after they have deflated. If problems develop inside the pleural cavity, people can experience difficulty breathing.
This structure is also known as the pleural space or pleural membrane. In healthy human beings, it is filled with a small amount of fluid which acts as a lubricant. As the lungs inflate, the lubricant allows the pleura to slide without resistance so that the lungs can expand and as they deflate, it reduces friction inside the pleural cavity so that the lungs deflate smoothly. Like other body fluids, pleural fluid cycles continuously, with the body constantly making more of the fluid while excess old fluid is carried away.
One problem which can emerge in the pleural cavity is mesothelioma, a type of cancer which attacks the tissues found in the pleural cavity. People most commonly develop this cancer as a result of exposure to asbestos, which irritates the lungs and contributes to the eventual development of tumors. These tumors can spread quickly, and they are difficult to eradicate successfully, especially if the cancer is caught late.
Another issue which can happen is pleural effusion, in which too much fluid builds up inside the pleural cavity, making it difficult to breathe. This condition is often associated with chronic conditions like congestive heart failure. Patients can also experience pneumothorax, in which the pleural space fills with air, usually as a result of trauma. It is important to note that because the pleural cavities are separate, it is possible to have a problem on one side and not the other.
Medical imagining studies of the chest can reveal this anatomical structure and provide information about any problems or areas of malfunction, as well. For example, in someone with pleural effusion or pneumothorax, the pocket of fluid or air can be seen on an x-ray. Other imaging such as MRI can be used to gather more data, including sectional views which provide imaging of the lungs from different angles. These views can be useful for pinpointing the extent of a problem in the lungs.