Our leg veins carry blood up to the heart, flowing against the downward force of gravity. Valves within our leg veins open and close, allowing the blood to flow in an upward direction. These valves close intermittently to stop the blood from flowing in a downward direction.
Our vein valves can eventually become weak and stop functioning the way they’re supposed to, causing blood to leak down and gather in the legs. This backup and accumulation of blood in the legs creates new, superficial veins just under the skin’s surface, and these are called spider veins.
Even though these small veins look like small insignificant veins under the skin, they are an indicator of a deeper vascular problem inside your leg veins.