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Pleura and pleural cavity copy
- 1. PLEURA AND PLEURALCAVITY
- 2. PLEURA Pleural cavityis lined by single layer of flat cells, “mesothelium” and an associated layer of supporting connective tissue; together they form pleura.
- 3. PLEURA parietal pleura:pleura associated with the walls of a pleural cavity visceral pleura :pleura, which adheres to and covers the lung: reflects from the medial wall and onto the surface of the lung
- 4. DEVELOPMENT OF PLEURA each lung bud invaginates the wall of coelomic cavity and then grows to fill a greater part of the cavity lung is covered with visceral pleura and the thoracic wall is lined with parietal pleura original coelomic cavity is reduced to slitlike space called the pleural cavity as a result of the growth of the lung.
- 5. SUPRAPLEURAL MEMBRANE thickeningof connective tissue that covers the apex of lung extension of endothoracic fascia that exists between parietal pleura and thoracic cage extends between inner border of first rib and transverse process of C7 vertebra act as a rigid barrier so as to prevent changes in intrathoracic pressure drawing upon the contents of the neck
- 6. PARTS OF PARIETALPLEURA costal part diaphragmatic part mediastinal part cervical pleura
- 7. CUPOLA OR CERVICALPART the dome-shaped layer of parietal pleura lining the cervical extension of the pleural cavity cervical pleura extends up into the neck, lining the undersurface of the suprapleural membrane It reaches a level 1 to 1.5 in. (2.5 to 4 cm) above the
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- 9. COSTAL PART pleurarelated to the ribs and intercostal spaces
- 10. DIAPHRAGMATIC PART pleuracovering the diaphragm
- 11. REFLECTIONS OF PARIETALPLEURA Superiorly: pleural cavity can project as much as 3- 4 cm above the first costal cartilage
- 12. Anteriorly: pleural cavitiesapproach each other posterior to the upper part of the sternum. posterior to the lower part of the sternum, the parietal pleura does not come as close to the midline on the left side
- 13. Inferiorly: Inthe midclavicular line, the pleural cavity extends inferiorly to rib VIII. In the midaxillary line, it extends to rib X. From this point, the inferior margin courses horizontally, to reach vertebra XII
- 15. VISCERAL PLEURA o Visceralpleura is continuous with parietal pleura at the hilum of each lung. o The visceral pleura is firmly attached to the surface of the lung, including both opposed surfaces of the fissures that divide the lungs into lobes.
- 16. PULMONARY LIGAMENT Theparietal pleura surrounding the root of the lung extends downwards beyond the root as a fold called the pulmonary ligament. The fold contains a thin layer of loose areolar tissue with a few lymphatics
- 17. Actually itprovides a dead space into which the pulmonary veins can expand during increased venous return as in exercise. The lung roots can also descend into it with the descent of the diaphragm
- 18. NERVE SUPPLY OFTHE PLEURA The parietal pleura is sensitive to pain, temperature, touch, and pressure The costal pleura is segmentally supplied by the intercostal nerves. The mediastinal pleura is supplied by the phrenic nerve. The diaphragmatic pleura is supplied over the domes by the phrenic nerve and around the periphery by the lower six
- 20. NERVE SUPPLY OFVISCERAL PLEURA The visceral pleura covering the lungs is sensitive to stretch but is insensitive to common sensations such as pain and touch. It receives an autonomic nerve supply from the pulmonary plexus
- 21. BLOOD SUPPLY Theparietal pleura is supplied by intercostal, internal thoracic and musculophrenic arteries. The veins drain mostly into the azygos and internal thoracic veins. The pulmonary pleura, like the lung, is supplied by the bronchial arteries
- 22. LYMPHATIC DRAINAGE PARIETALPLEURA: The lymphatics drain into the intercostal, internal mammary, posterior mediastinal and diaphragmatic nodes. VISCERAL PLEURA: It is drained by the bronchopulmonary lymph nodes.
- 24. PLEURAL CAVITY Twopleural cavities are situated on either side of the mediastinum During development, the lungs grow out of the mediastinum, becoming surrounded by the pleural cavities. As a result, the outer surface of each organ is covered by pleura
- 25. Each lungremains attached to the mediastinum by a root formed by the airway, pulmonary blood vessels, lymphatic tissues, and nerves Only a potential space normally exists between the visceral pleura covering lung and the parietal pleura lining the wall of the thoracic cavity
- 26. Two pleuralcavities, one on either side of the mediastinum, surround the lungs superiorly: extend above rib I into the root of the neck inferiorly: they extend to a level just above the costal margin medialy: wall of each pleural cavity is the mediastinum
- 27. PLEURAL RECESSES Thelungs do not completely fill the anterior or posterior inferior regions of the pleural cavities This results in recesses in which two layers of parietal pleura become opposed. Expansion of the lungs into these spaces usually occurs only during forced inspiration the recesses provide potential spaces in which fluids can collect and from which fluids can be aspirated
- 28. Costomediastinal recesses: Anteriorly, wherecostal pleura is opposed to mediastinal pleura. The largest is on the left side in the region overlying the heart.
- 29. COSTODIAPHRAGMATIC RECESS The largestand clinically most important recesses occur in each pleural cavity between the costal pleura and diaphragmatic pleura
- 30. The costodiaphragmaticrecesses are the regions between the inferior margin of the lungs and inferior margin of the pleural cavities They are deepest after forced expiration and shallowest after forced inspiration
- 31. PLEURAL FLUID Thepleural space normally contains 5 to 10 mL of clear fluid, which lubricates the apposing surfaces of the visceral and parietal pleura during respiratory movements The formation of the fluid results from hydrostatic and osmotic pressures
- 33. Since thehydrostatic pressures are greater in the capillaries of the parietal pleura than in the capillaries of the visceral pleura (pulmonary circulation), the pleural fluid is normally absorbed into the capillaries of the visceral pleura.
- 34. Any conditionthat increases the production of the fluid (e.g., inflammation, malignancy, congestive heart disease) or impairs the drainage of the fluid (e.g., collapsed lung) results in the abnormal accumulation of fluid, called pleural effusion The presence of 300 mL of fluid in the costodiaphragmatic recess in an adult is sufficient to enable its clinical detection The clinical signs include decreased lung expansion on the side of the effusion, with decreased breath sounds and dullness on
- 35. A collectionof pus in the pleural cavity is called an empyema Aspiration of any fluid from the pleural cavity is called paracentesis thoracis. It is usually done in the 8th intercostal space in the midaxillary line. The needle is passed through the lower part of the space to avoid injury to the principal neurovascular bundle.
- 36. PLEURISY Inflammation ofthe pleura (pleuritis or pleurisy), secondary to inflammation of the lung, results in the pleural surfaces becoming coated with inflammatory exudate, causing the surfaces to be roughened. This roughening produces friction, and a pleural rub can be heard with the stethoscope on inspiration and expiration. exudate becomes invaded by fibroblasts, which lay down collagen and bind the visceral pleura to the parietal pleura, forming pleural adhesions
- 37. PNEUMOTHORAX As theresult of disease or injury, air can enter the pleural cavity from the lungs or through the chest wall Stab wounds of the thoracic wall may pierce the parietal pleura so that the pleural cavity is open to the outside air This condition is called open
- 38. PNEUMOTHORAX In thesecircumstances, the air pressure builds up on the wounded side and pushes the mediastinum toward the opposite side In this situation, a collapsed lung is on the injured side and the opposite lung is compressed by the deflected mediastinum. This dangerous condition is called a tension pneumothorax
- 39. Air inthe pleural cavity associated with serous fluid is known as hydropneumothorax, associated with pus as pyopneumothorax, and associated with blood as hemopneumothorax
- 40. In hemopneumothorax, blood entersthe pleural cavity. It can be caused by stab or bullet wounds to the chest wall, resulting in bleeding from blood vessels in the chest wall, from vessels in the chest cavity, or from a lacerated lung
- 42.