The two pleural membranes should be touching. If air creates a space between them the air will push the lung down and prevent it from filling with air. This is known as a collapsed lung, or pneumothorax. The air between the pleural membranes must be removed to reinflate the lung.
The potential space between the pleural membranes is called the thoracic cavity. This is also known as the pleural cavity in some instances.
The space part is because there is nothing between the membranes but it is only potential space because there is no actual space between the bordering membranes, they touch together/
The lungs are surrounded by two membranes, the pleurae. The outer pleura is attached to the chest wall and is known as the Parietal pleura; the inner one is attached to the lung and other visceral tissues and is known as the Visceral pleura. In between the two is a thin space known as the pleural cavity or pleural space. It is filled with pleural fluid, a serous fluid produced by the pleura.
pleural space
The mediastinum.
the small potential space between the parietal and visceral layers of the pleura.
The heart.
Pleural pressure is negative (lower than alveolar pressure or barometric pressure) because of a "suction effect" caused by lung recoil. As the lungs recoil elastically, the inner and outer pleural membranes tend to be pulled apart but fluid within the pleural cavity keeps the inner and outer pleural membranes close together. This pulling force decreases the pressure between the inner and outer membranes lining the pleural cavity - an effect that can be appreciated by stacking several plastic cups together, submersing the stack in soapy water ensuring that the spaces between the cups fill with water, and then lift the stack of cups out of the water and try to pull the cups apart. A suction effect will occur producing negative pressure in fluid-filled spaces between the cups as you attempt to pull them apart. The fluid-filled space between the cups is like the fluid-filled space in the pleural cavity. That is why pleural pressure is negative.
The two pleural membranes are the visceral pleura and the parietal pleura. The visceral pleura is the innermost layer that covers the surface of the lungs, while the parietal pleura lines the chest cavity. These membranes create a fluid-filled space called the pleural cavity, which helps to reduce friction and allows for smooth movement of the lungs during breathing.
Pleural cavity
The lungs are surrounded by two membranes, the pleurae. The outer pleura covers and is attached to the chest wall and is known as the parietal pleura. The inner one covers and is attached to the lung and other visceral tissues i.e. vessels, bronchi and nerves and is known as the visceral pleura. In between the two is an actual thin space known as the pleural cavity or pleural space normally containing a small amount of pleural fluid.=The parietal pleura is highly sensitive to pain; the visceral pleura is not.=
The mediastinum is the space between the pleural cavities that contains the heart, thymus, trachea, and esophagus.