Pulmonary pleurae

Pulmonary pleurae
A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there is no space between the pulmonary pleurae and between the pericardium and heart.
Details
Nerve	intercostal nerves, phrenic nerves
Identifiers
Latin	pleurae pulmonarius
Code	TH H3.05.03.0.00006
Anatomical terminology []

The pulmonary pleurae are the two pleurae of the invaginated sac surrounding each lung and attaching to the thoracic cavity. The visceral pleura is the delicate serous membrane that covers the surface of each lung (the lung parenchyma) and dips into the fissures between the . The parietal pleura is the outer membrane which is attached to the inner surface of the thoracic cavity. It also separates the pleural cavity from the mediastinum. The parietal pleura is innervated by the intercostal nerves and the phrenic nerve.

Between the membranes is a fluid filled space called the pleural cavity.

The visceral pleura is a delicate serous membrane that closely covers the surfaces of the lungs and dips into the fissures that separate the lobes.

The parietal pleura is the outer membrane that attaches to and lines the inner surface of the thoracic cavity, covers the upper surface of the diaphragm and is reflected over structures within the middle of the thorax. It separates the pleural cavity from the mediastinum.

The parietal pleura is differentiated into regions in line with the location in the thorax. The ‘’cervical pleura’’ (or ‘’cupula of pleura’’) is in the region of the cervical vertebrae extending beyond the apex of the lung and into the neck. The ‘’costal pleura’’ lines the inner surfaces of the ribs and the intercostal muscles and are separated from them by endothoracic fascia. An extension of the endothoracic fascia known as the suprapleural membrane covers the apex of each lung in a thickened layer of connective tissue. The ‘’diaphragmatic pleura’’ lines the convex surface of the diaphragm. The ‘’mediastinal pleura’’ attaches to the other in the mediastinum and forms the separating lateral wall.

Between the two membranes is a space called the pleural cavity or interpleural space which contains a lubricating fluid.

The contraction of the diaphragm creates a negative pressure within the pleural cavity which forces the lungs to expand resulting in passive exhalation and active inhalation. This breathing process can be made forceful through the contraction of the external intercostal muscles which forces the rib cage to expand and add to the negative pressure in the pleural cavity causing the lungs to fill with air. The fluid in the cavity provides lubrication and cushioning.