Lymph is the immune organ of the body and is distributed throughout the body, especially in the anatomical fossa. The most common lymph nodes are the submandibular lymph nodes, the subchin lymph nodes, the anterior and posterior cervical lymph nodes, the supraclavicular lymph nodes, and the axillary lymph nodes. In the abdomen, there are intra-abdominal lymph nodes, upper and lower mesenteric lymph nodes, lumbar lymph nodes, inguinal lymph, and popliteal lymph nodes. In fact, lymph nodes are widely distributed, and lymph nodes are only a part of the organ, and there is a lymphatic system consisting of lymphatic vessels, lymph nodes, as well as lymphatic fluid and lymphatic tissue. Lymph nodes are the site of lymphocyte settlement and restricted immune response, which is the normal protective barrier of the body, capable of removing foreign substances and capable of producing immune response. Enlarged lymph nodes can be seen when bacterial infections tumors or non-specific fine bacterial infections are present.