GUIDES
Thorax: Lungs
[Plate 192, Lungs in Situ: Anterior View]Thoracic Cavity, Pleurae and Pleural Cavity
Thoracic cavity has
two lateral pleural cavities, containing the lungs and pleurae
a central compartment, the mediastinum, containing all the other thoracic structures
Each lung is surrounded by, and covered with, a continuous membrane, which is defined as
the visceral pleura, which covers the lungs and cannot be dissected from the lung
the parietal pleura, which lines the pleural cavities
The visceral and parietal pleura are continuous at the hilum of the lung where structures enter and leave the lung (bronchus, pulmonary
vessels, bronchial vessels, lymphatics)
The parietal pleura has four named parts:
Costal pleura lining the internal surface of the thoracic wall
Mediastinal pleura covering the sides of the mediastinum
Diaphragmatic pleura covering the superior surface of the dome of each hemidiaphragm
Cervical pleura-a dome of pleura extending superiorly into the superior thoracic aperture
Visceral pleura does not have any general sensory innervation and is insensitive to pain
The parietal pleura is very sensitive to pain because of its sensory supply by branches of the intercostal and phrenic nerves
The pleural cavity is the potential space between the parietal and visceral pleura.
The pleural cavity contains a thin layer of serous pleural fluid, which lubricates and allows the pleurae to move smoothly over each
other during respiration.
Surface tension keeps the lung surface in contact with the thoracic wall.
The lung expands and fills with air when the thoracic cavity expands.Lines of pleural reflection
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