The pleura (from Greek πλευρά "edge", "rib"), German pleura is a thin serous skin in the chest cavity . It covers the lungs and lines the inside of the chest cavity. The pleura forms the pleural cavity (the pleural space).
As pleura (Latin visceral pleura or visceral pleura ) and the inner sheet (visceral) pleura covers the lungs.
As a pleura in the narrower sense (Latin pleura parietalis ) or outer leaf, the (parietal) pleura lines the chest cavity from the inside. There are four more areas:
- The pleural domes ( Cupulae pleurae ) is the part facing the head of the lung dome.
- The pleura ( pars costalis ) is the part that covers the inside of the ribs .
- The pars mediastinalis ( middle layer) is located on the connective tissue of the mediastinum in the center of the chest.
- The pars diaphragmatica lies on the top of the diaphragm .
Histologically, the pleura consists of a single-layer squamous epithelium , which is ontogenetically derived from the mesothelium , and a lamina propria . The two pleural leaves turn into one another at the hilus of the lungs and the ligamentum pulmonale . They are separated from each other by the pleural cavity ( Cavitas pleuralis ), a thin, pressure-tight gap that is filled with serous fluid. Effusions can collect or metastases in the pleural cavity .
The pleura has reserve bulges ( recesses ) towards the foot (at the edges of the diaphragm) and towards the center of the chest (in the mediastinum) to ensure the lungs expand during the breathing process . These reserve spaces are never completely filled, even with deep inspiration. The parietal pleura forms four deep folds:
- Costodiaphragmatic recess
- Costomediastinal recess
- Phrenicomediastinal recess
- Vertebromediastinal recess
The sensitive nerve supply of the pleura take over branches of the tenth cranial nerve ( vagus nerve ), the phrenic nerve (Pars mediastinal and diaphragmatic) and the intercostal nerves (costal). The lung membrane, on the other hand, probably has no pain sensation .
The pleural leaves produce and absorb the fluid in the pleural space (especially on the parietal side of the pleura) and, in healthy people, create a balance that is dependent on hydrostatic pressure (gravity pressure) and oncotic (osmotic) pressure . The fluid turnover is about 0.2 ml per kilogram and hour, so that the pleural fluid is exchanged within about an hour.
The lung membrane is a sliding layer for the movements of the lungs. It is an absolutely necessary, suction- mediating medium for breathing: Due to the relative negative pressure in the pleural space and the capillary adherence of the pleural leaves, the lungs have to follow the active expansion of the chest wall muscles and the diaphragm when inhaling.
If the relative negative pressure between the two pleural leaves is removed (such as by air flowing in in the event of a stab injury), the lungs no longer follow the expanding chest when inhaling, which ultimately leads to the collapse of the lung, which is dependent on expansion ( pneumothorax ).
Examination of the pleura
Apart from questioning the patient ( anamnesis ), various examination methods are possible:
- Auscultation (eavesdropping)
- Sonography (ultrasound)
- Radiographs of the thorax in two planes
- Computed tomography
- Thoracoscopy ( endoscopic assessment of the pleural space)
- Biopsy for cytodiagnostics and bacteriological examinations
Diseases of the pleura
- Pleurisy ( pleurisy ) in the forms of pleuritis sicca (without effusion), exudative pleurisy (with effusion) and (depending on location) mediastinal pleurisy, diaphragmatic pleuritis and interlobaric pleurisy
- Pleural empyema (purulent pleurisy)
- Pleural effusion
- Pleural expectations
- Pleural tumors (pleural tumors ), including benign ( fibromas , lipomas , hemangiomas ) and malignant ( pleural mesothelioma )
- Pleural carcinosis : pleural (drip) metastasis of tumors, especially breast cancer
- Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , pp. 97-100 ( infections of the pleura ).
- Joachim Frey : Diseases of the respiratory organs. In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition, ibid. 1961, pp. 599-746, here: pp. 724-743.
- Berthold Jany, Tobias Welte: Pleural effusion in adults - causes, diagnosis and therapy. In: Deutsches Ärzteblatt. Volume 116, Issue 21, 2019, pp. 377–385, here: p. 378.