Pleura is located in the thoracic cavity, is lined with the inner surface of the chest wall, the surface of the lungs, the thoracic surface of the mediastinum and the diaphragm above a layer of smooth plasma membrane, which can be divided into the dirty pleura and the wall pleura two parts. 1. Dirty pleura: it covers the surface of the lungs, is closely integrated with the lungs and cannot be separated, and extends into the interlobar fissures along with the lung lobes. 2. Wall pleura: it can be divided into 4 parts due to different attachments: (1) costal pleura: it is attached to the inner surface of intercostal muscles of chest wall. (2) Mediastinal pleura: attached to the thoracic surface on both sides of the mediastinum, including the plasma membrane covered in the pericardium outside of the pericardium, i.e. pericardium. (3) Diaphragmatic pleura: attached to the upper part of the diaphragm, tightly connected to the diaphragm, not easy to peel off. (4) Pleural apex: covering the lungs above the apices, the highest point is located in the medial third of the clavicle above the 2-3cm. Pleural diseases are more common in clinic: such as pneumothorax, pleural effusion, pleurisy, pleural tumors, etc. If you have pleural diseases, it is recommended to go to the hospital for further diagnosis and treatment.