The left lung is connected to the heart, and the front and rear ribs protect it. There is a layer of visceral pleura on the lung surface, which is close to the chest wall. The other side is called parietal pleura. The pleural cavity is negative pressure. If the respiratory muscles contract, the chest will expand, and then breathe in fresh air. If the respiratory muscles relax, the chest wall will shrink elastically, and carbon dioxide will also be exhaled. The upper end of the lungs of the normal human body is located in the supraclavicular recess, and the lower boundaries of the two lungs change with the change of respiratory movement, generally between the 8th and 10th ribs along the subscapular line of the back. However, for patients with respiratory diseases, the specific location of lung tissue will be different.
