The subclavian lymph nodes, also called deltoid pectoral lymph nodes, are located below the clavicle, inside the groove between deltoid and pectoralis major muscles, and are arranged along the cephalic vein, and their output lymphatic vessels will inject into the axillary lymph nodes and a few into the supraclavicular lymph nodes. Because of the specificity of its physiological location, some digestive tract tumors, breast tumors and malignant thyroid tumors may cause enlargement of lymph nodes here, so once they are found, they need to pay attention to them and go to the hospital in time for examination, local puncture and clear diagnosis. Since lymph nodes are also immune organs, when viruses or bacteria invade the body, they may also cause local lymph node enlargement.