Clinical Support

The circulatory system

The circulatory system in the lower extremity is comprised of the arterial system that delivers nutrient and oxygen rich blood to the tissues through the arteries and capillaries. The venous system is made up of a network of veins that have the distinctive function to return blood back to the heart for re-oxygenating and refueling.

Superficial veins

The superficial veins are visible just below the surface of the skin. The longest and largest of these veins, called the great saphenous vein, is connected to the femoral vein and courses down the medial (inner) aspect of the thigh and leg. The smaller saphenous vein begins behind the knee and runs down the posterior (back) of the calf. Like the great saphenous, it has branches that extend under the skin in several directions.

Deep veins

Greatest percentage of blood from deep veins are veins that run deep inside your leg muscles. These veins carry the greatest of blood from your legs to your heart. Perf

Perforating veins

Perforating veins connect the superficial veins and the deep veins. Because the blood flows faster through the deep veins, the blood in the superficial veins is pulled and emptied into the deep veins.

How veins work


Valves play a critical role in helping blood flow through the veins to the heart. Like swinging doors, valves float open to allow blood to flow toward the heart and flap closed again to prevent the flow of blood back down the extremities. Vein walls are made up of elastic fibers that are supported by a muscular layer that can become overstretched, or dilated, that prevent the valves from closing completely. The result of this incompetent valve is called venous reflux, or the “back flow” of blood. This insufficiency can cause symptoms of swelling, pain, itching, burning, skin discoloration, and even leg ulcers. 

open venous valve and closed venous valve

The role of gravity in vein disease

To understand this problem, think of a city water tower. More specifically, the taller the tower, the greater the water pressure that it creates. A vein follows the same principles. Think of the veins and arteries in the body as “columns” of blood. When standing, the columns of blood are at their tallest. Without considering any factors other than gravity, the pressure inside the veins of the leg, at the ankle, of a 5’10” individual while standing would be approximately 80 to 100 mmHg. When lying down, the pressure inside the same veins, at how do veins work? Open venous valve Closed venous valve the ankle, would only be about 10 mmHg. The increased pressure inside the veins while standing decreases the normal return of fluid from the tissues into the circulatory system. That is why standing causes swelling of the feet and ankles.

creating blood flow with calf pump

The flexion and extension of the calf muscle initiates
blood flow back to the heart for replenishment. This
action compressed the vein walls that pushed the
blood through the vessels. With repetition, the blood
essentially climbs back to the heart through the
support of the valves.

This is why it is recommended to not sit for long
periods at work, school, or during travel. The
continuous movement allows the blood to recirculate
preventing pooling that may lead to clots, or thrombi.
Long periods of inactivity or people with compromised
conditions can get Deep Vein Thrombosis than can be
dangerous and even life threatening.