The middle mediastinum contains the heart and the roots of large blood vessels entering and exiting the heart, such as the superior vena cava, inferior vena cava, pulmonary artery and pulmonary vein, ascending aorta, etc., as well as the phrenic nerve and lymph nodes that penetrate the surface of the heart. The middle mediastinal pericardium consists of an outer fibrous layer and an inner plasma membrane layer. The outer fibrous layer is poorly malleable, and when pericardial effusion occurs, the effusion cannot expand outward, but can only compress the heart inward, resulting in pericardial tamponade. The plasma layer pericardium can be divided into inner and outer layers. When pathogens such as bacteria and viruses are infected, it can lead to adhesion of the inner and outer layers, and the systolic and diastolic functions of the heart are limited. The surface of the heart has many sources of nerves, mainly the phrenic nerve, with the rest being the intercostal nerves, esophageal and pulmonary plexus nerves, etc. These nerves transmit sensory and motor impulses. Lymphatic circulation from the pericardial surface can eventually be injected into the supradiaphragmatic lymph nodes and anterior and posterior mediastinal lymph nodes. Lymphomas, organ cysts, and paragangliomas can occur in the middle mediastinum. If a tumor is detected, the patient is advised to undergo early treatment without delay and delay.