In human anatomy, the pleural cavity is the body cavity that contains the lungs. The lungs are surrounded by two serous membranes, the pleurae. The outer pleura (parietal pleura) covers and is attached to the chest wall. The inner pleura (visceral pleura) covers and is attached to the lung and other structures, i.e. blood vessels, bronchi and nerves. The thin space between the two pleura is known as the pleural space; it normally contains a small amount of pleural fluid.

The parietal pleura is highly sensitive to pain; the visceral pleura is not due to its lack of sensory innervation.^[1]

Functions

Pleural fluid serves several functions. It lubricates the pleural surfaces, thus allowing the pleural layers to slide easily against each other during ventilation. The surface tension resulting from the presence of the pleural fluid keeps the lung surfaces in close apposition to the chest wall. This allows for optimal inflation of the alveoli during respiration. It also directly transmits pressures from the chest wall to the visceral pleural surface (and hence, the lung). In this manner, movements of the chest wall, particularly during heavy breathing, are coupled to movements of the lungs.

Blood supply

In humans, the visceral pleura has a dual blood supply, receiving blood from the bronchial and from the pulmonary arteries.

Fluid

It is filled with pleural fluid, a serous fluid produced by the pleura. A normal 70 kg human has approximately 12-15 mL of pleural fluid.

In normal pleurae, most fluid is produced by the parietal circulation (intercostal arteries) via bulk flow and reabsorbed by the lymphatic system. Thus, pleural fluid is continuously produced and reabsorbed. The rate of reabsorption may increase up to 40x before significant amounts of fluid accumulate within the pleural space.

In humans, there is no anatomical connection between the left and right pleural cavities, so in cases of pneumothorax (see below), the other hemithorax will still be able to function normally.

See also

• Pleural disease
• Vertebrate trachea
• Capillaries
• Larynx
• Pharynx
• Epiglottis
• Rings of cartilage
• Bronchus
• Bronchioles
• Thoracic cavity

Additional images

<gallery> Image:Gray1032.png|The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind. </gallery>

References

1. ↑ p132 Clinically Oriented Anatomy, 5th edition. Moore and Dalley.

External links

• Photo of dissection at kenyon.edu

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