The deep veins of the lower extremity are divided from top to bottom into the common femoral vein, superficial femoral vein and deep femoral vein, and the superficial femoral vein and popliteal vein are divided into anterior tibial vein, posterior tibial vein and peroneal vein below the popliteal fossa. The clinical significance of the deep veins of the lower extremities is that if a thrombus occurs, it can be shed directly to the heart through the deep veins of the lower extremities and pumped into the pulmonary artery through the heart to cause pulmonary embolism. Once a deep vein thrombosis occurs it should be treated promptly to prevent life-threatening conditions. There is a traffic branch between the deep vein and superficial vein of the lower extremity, and sometimes the superficial vein may dislodge to the deep vein, but it is generally unlikely.