According to the anatomical structure of the human body, the organs under the left side of the ribs generally refer to the left side of the midline of the human body, including the left lung, spleen, and part of the intestines, adrenal glands, and part of the liver located in a line to the left of the median line. Combining anatomical structures, symptoms and signs can be helpful for disease analysis, as explained below: 1. The left lung belongs to the left subcostal organ, and when a left rib fracture occurs after a serious trauma, the left lung injury is likely to occur, at which time, in addition to paying attention to the fracture site situation, we should also pay attention to the respiratory system symptoms. 2. In addition to paying attention to the rib and left lung situation, the left subcostal trauma requires attention to the spleen, intestine, liver, adrenal gland, etc. In addition to the injury to the spleen, intestine, liver, kidney and other organs, whole abdominal ultrasound, CT or nuclear magnetic examination is feasible to assist the diagnosis to avoid missing diagnosis.3. Patients with left lung tumor when metastasis occurs firstly involve the neighboring organs, such as metastasis to the hilar lymph nodes, pleural ribs and other parts. Therefore, the clinical diagnosis of disease is very closely related to the anatomical structure of the body, and it is necessary to be familiar with its physiological functions so that accurate analysis and prognosis can be made when pathological damage occurs, which can help the diagnosis and treatment of disease.