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Pleural cavity
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Pleural cavity
The pleural cavity, or pleural space (or sometimes intrapleural space), is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient.
The serous membrane that covers the surface of the lung is the visceral pleura and is separated from the outer membrane, the parietal pleura, by just the film of pleural fluid in the pleural cavity. The visceral pleura follows the fissures of the lung and the root of the lung structures. The parietal pleura is attached to the mediastinum, the upper surface of the diaphragm, and to the inside of the ribcage.
In humans, the left and right lungs are completely separated by the mediastinum, and there is no communication between their pleural cavities. Therefore, in cases of a unilateral pneumothorax, the contralateral lung will remain functioning normally unless there is a tension pneumothorax, which may shift the mediastinum and the trachea, kink the great vessels, and eventually collapse the contralateral cardiopulmonary circulation.
The visceral pleura receives its blood supply from the parenchymal capillaries of the underlying lung, which have input from both the pulmonary and the bronchial circulation. The parietal pleura receives its blood supply from whatever structures underlie it, which can be branched from the aorta (intercostal, superior phrenic, and inferior phrenic arteries), the internal thoracic (pericardiacophrenic, anterior intercostal, and musculophrenic branches), or their anastomosis.
The visceral pleurae are innervated by splanchnic nerves from the pulmonary plexus, which also innervates the lungs and bronchi. The parietal pleurae however, like their blood supplies, receive nerve supplies from different sources. The costal pleurae (including the portion that bulges above the thoracic inlet) and the periphery of the diaphragmatic pleurae are innervated by the intercostal nerves from the enclosing rib cage, which branches off from the T1-T12 thoracic spinal cord. The mediastinal pleurae and central portions of the diaphragmatic pleurae are innervated by the phrenic nerves. which branches off the C3-C5 cervical cord. Only the parietal pleurae contain somatosensory nerves and are capable of perceiving pain.
During the third week of embryogenesis, each lateral mesoderm splits into two layers. The dorsal layer joins the overlying somites and ectoderm to form the somatopleure; and the ventral layer joins the underlying endoderm to form the splanchnopleure. The dehiscence of these two layers creates a fluid-filled cavity on each side, and with the ventral infolding and the subsequent midline fusion of the trilaminar disc, forms a pair of intraembryonic coeloms anterolaterally around the gut tube during the fourth week, with the splanchnopleure on the inner cavity wall and the somatopleure on the outer cavity wall.
The cranial end of the intraembryonic coeloms fuse early to form a single cavity, which rotates invertedly and apparently descends in front of the thorax, and is later encroached by the growing primordial heart as the pericardial cavity. The caudal portions of the coeloms fuse later below the umbilical vein to become the larger peritoneal cavity, separated from the pericardial cavity by the transverse septum. The two cavities communicate via a slim pair of remnant coeloms adjacent to the upper foregut called the pericardioperitoneal canal. During the fifth week, the developing lung buds begin to invaginate into these canals, creating a pair of enlarging cavities that encroach into the surrounding somites and further displace the transverse septum caudally — namely the pleural cavities. The mesothelia pushed out by the developing lungs arise from the splanchnopleure, and become the visceral pleurae; while the other mesothelial surfaces of the pleural cavities arise from the somatopleure, and become the parietal pleurae.
The tissue separating the newly formed pleural cavities from the pericardial cavity are known as the pericardiopleural membranes, which later become the side walls of the fibrous pericardium. The transverse septum and the displaced somites fuse to form the pleuroperitoneal membranes, which separates the pleural cavities from the peritoneal cavity and later becomes the diaphragm.
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Pleural cavity AI simulator
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Pleural cavity
The pleural cavity, or pleural space (or sometimes intrapleural space), is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient.
The serous membrane that covers the surface of the lung is the visceral pleura and is separated from the outer membrane, the parietal pleura, by just the film of pleural fluid in the pleural cavity. The visceral pleura follows the fissures of the lung and the root of the lung structures. The parietal pleura is attached to the mediastinum, the upper surface of the diaphragm, and to the inside of the ribcage.
In humans, the left and right lungs are completely separated by the mediastinum, and there is no communication between their pleural cavities. Therefore, in cases of a unilateral pneumothorax, the contralateral lung will remain functioning normally unless there is a tension pneumothorax, which may shift the mediastinum and the trachea, kink the great vessels, and eventually collapse the contralateral cardiopulmonary circulation.
The visceral pleura receives its blood supply from the parenchymal capillaries of the underlying lung, which have input from both the pulmonary and the bronchial circulation. The parietal pleura receives its blood supply from whatever structures underlie it, which can be branched from the aorta (intercostal, superior phrenic, and inferior phrenic arteries), the internal thoracic (pericardiacophrenic, anterior intercostal, and musculophrenic branches), or their anastomosis.
The visceral pleurae are innervated by splanchnic nerves from the pulmonary plexus, which also innervates the lungs and bronchi. The parietal pleurae however, like their blood supplies, receive nerve supplies from different sources. The costal pleurae (including the portion that bulges above the thoracic inlet) and the periphery of the diaphragmatic pleurae are innervated by the intercostal nerves from the enclosing rib cage, which branches off from the T1-T12 thoracic spinal cord. The mediastinal pleurae and central portions of the diaphragmatic pleurae are innervated by the phrenic nerves. which branches off the C3-C5 cervical cord. Only the parietal pleurae contain somatosensory nerves and are capable of perceiving pain.
During the third week of embryogenesis, each lateral mesoderm splits into two layers. The dorsal layer joins the overlying somites and ectoderm to form the somatopleure; and the ventral layer joins the underlying endoderm to form the splanchnopleure. The dehiscence of these two layers creates a fluid-filled cavity on each side, and with the ventral infolding and the subsequent midline fusion of the trilaminar disc, forms a pair of intraembryonic coeloms anterolaterally around the gut tube during the fourth week, with the splanchnopleure on the inner cavity wall and the somatopleure on the outer cavity wall.
The cranial end of the intraembryonic coeloms fuse early to form a single cavity, which rotates invertedly and apparently descends in front of the thorax, and is later encroached by the growing primordial heart as the pericardial cavity. The caudal portions of the coeloms fuse later below the umbilical vein to become the larger peritoneal cavity, separated from the pericardial cavity by the transverse septum. The two cavities communicate via a slim pair of remnant coeloms adjacent to the upper foregut called the pericardioperitoneal canal. During the fifth week, the developing lung buds begin to invaginate into these canals, creating a pair of enlarging cavities that encroach into the surrounding somites and further displace the transverse septum caudally — namely the pleural cavities. The mesothelia pushed out by the developing lungs arise from the splanchnopleure, and become the visceral pleurae; while the other mesothelial surfaces of the pleural cavities arise from the somatopleure, and become the parietal pleurae.
The tissue separating the newly formed pleural cavities from the pericardial cavity are known as the pericardiopleural membranes, which later become the side walls of the fibrous pericardium. The transverse septum and the displaced somites fuse to form the pleuroperitoneal membranes, which separates the pleural cavities from the peritoneal cavity and later becomes the diaphragm.
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