https://youtu.be/0edPmmy3t4g?si=Iee9zkKBR0BDemCA

https://youtu.be/Ccya8KXu9xg?si=IqbhpeCEWTQVIEsY

Each pleural cavity is lined by a single layer of flat cells called mesothelium, along with a layer of supporting connective tissue. Together, they form the pleura.

• The pleura consists of two layers:

• The visceral pleura adheres to and covers the lung tissue internally, while the parietal pleura covers and lines the external thoracic cage.

• The pleura can be categorized into two major types based on location: the parietal pleura, which is associated with the walls of the pleural cavity, and the visceral pleura, which adheres to and covers the lung. Each pleural cavity is the potential space enclosed between the visceral and parietal pleurae. Normally, this space contains only a very thin layer of serous fluid. The presence of this space is indicated by the potential for fluid to collect inside, which helps lubricate during respiration.

• As a result, the lung's surface, covered by the visceral pleura, directly opposes and freely slides over the parietal pleura attached to the wall.

The functions of the pleura are protection and the production of fluid for lubrication.

If the fluid in the pleural cavity decreases, it may lead to the development of friction and subsequent pleuritis. Pleuritis is a very painful condition where the patient experiences pain between the ribs and painful breathing.

The pleural cavity is a site for various conditions such as pneumothorax, pleural effusion, empyema, and hemothorax. Normally, only lubricated fluid is found in this space. Pneumothorax refers to the accumulation of air in the pleural sac, pleural effusion is the accumulation of fluid in the pleural sac, empyema is the accumulation of pus in the pleural sac after chronic infection, and hemothorax is the collection of blood in the sac.

The names given to the parietal pleura correspond to the parts of the wall with which they are associated. The pleura related to the ribs and intercostal spaces is termed the costal part, while the pleura covering the diaphragm is called the diaphragmatic part. The pleura above the diaphragm and associated with the base of the lung is also referred to as the mediastinal part.

<aside> 👉 the parietal and visceral layer adhere together forming a sleeve around the hilum and then form what is called pulmonary ligament.

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• The dome-shaped layer of parietal pleura that lines the cervical extension is called the cervical pleura, also known as the dome of pleura or pleural cupola. It is covered by the suprapleural membrane, which is Sibson's fascia, the investing deep fascia of the neck. This membrane descends downward from its attachment at the superior thoracic aperture and becomes continuous with the outer covering of the apex of the lung.