In humans, the left and right lungs are completely separated by the mediastinum, and there is no communication between their<unk> es. 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<unk> 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<unk> receives its blood supply from whatever structures underlying 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<unk>  are innervated by splanchnic nerves from the pulmonary plexus, which also innervates the lungs and bronchi. The parietal<unk>  however, like their blood supplies, receive nerve supplies from different sources. The costal<unk>  (including the portion that bulges above the thoracic inlet) and the periphery of the diaphragmatic<unk>  are innervated by the intercostal nerves from the enclosing rib cage, which branches off from the T1-T12 thoracic spinal cord. The mediastinal<unk>  and central portions of the diaphragmatic<unk>  are innervated by the phrenic nerves. which branches off the C3-C5 cervcial cord. Only the parietal<unk>  contain somatosensory nerves and are capable of perceiving pain. Development 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<unk>  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<unk>  wall and the somatopleure on the outer<unk>  wall. The cranial end of the intraembryonic coeloms fuse early to form a single<unk> , which rotates invertedly and apparently descends in front of the thorax, and is later encroached by the growing primordial heart as the pericardial<unk> . The caudal portions of the coeloms fuse later below the umbilical vein to become the larger peritoneal<unk> , separated from the pericardial<unk>  by the transverse septum. The two<unk> es 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<unk> es that encroach into the surrounding somites and further displace the transverse septum caudally — namely the<unk> es. The mesothelia pushed out by the developing lungs arise from the splanchnopleure, and become the visceral<unk> ; while the other mesothelial surfaces of the<unk> es arise from the somatopleure, and become the parietal<unk> . The tissue separating the newly formed<unk> es from the pericardial<unk>  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<unk> es from the peritoneal<unk>  and later becomes the diaphragm.
Pleural cavity
Lung cavity
Indium lung
Endobronchial valve
Thoracic inlet
Pulmonary bay
Thoracic diaphragm
Subclavian loop