The veins of the human body include deep veins and superficial veins. Deep veins travel deeper and are generally located in the deeper layers of the muscle. Superficial veins are shallow and are generally located in the superficial fascia. The deep veins collect the blood supply from deep muscles and tendons. The superficial veins collect the blood supply from the subcutaneous area. The superficial veins normally travel for some time and then inject into the deep veins. Clinically, the veins are mainly blocked or dilated. When the deep veins are dilated, the clinical symptoms are not very obvious. When the superficial veins are dilated, the symptoms are not very obvious. When the superficial veins are dilated, varicose veins of the lower limbs occur on the surface of the body. When the deep veins are blocked, it will cause obvious swelling of the limbs and deep vein thrombosis, while the symptoms of superficial vein thrombosis are not obvious.