Superficial veins and deep veins
The venous system has superficial and deep components. The superficial veins are the veins that are “not deep”. It is as simple as that. The “deep veins” are not visible to the eye and are found below fascial tissue, in the musculature of the thighs and legs. Above the groin, the veins are all deep except for the veins on the walls of the abdomen and chest. The deep veins at or above the groin are the common femoral veins, iliac veins, vena cava and so on. The deep veins accept blood or tributary veins from the superficial system, such as the branches of the great and small saphenous veins. These drainage points are at the level of the knee (saphenopopliteal junction) or at the level of the groin (saphenofemora junction). This is the truncal system, namely the drainage system along the long axis of the body.
Veins also drain from the superficial system into the deep system via perforator veins. This is the perforator system that works in the ‘short axis’ of the body, from skin to deep directly through muscle fascia. When this system works properly, the veins drain blood from the skin and subcutaneous tissues directly in to the deep veins through the perforator system.
When the venous system is working properly, blood from the great saphenous veins drains one way into the deep veins at the level of the groin into the saphenofemoral junction and into the common femoral veins and up to the heart. Similarly, venous blood in the small saphenous vein drains into the deep veins, namely the popliteal vein which is a continuation of the femoral vein at the level of the knee. Also, venuos blood goes through the perforator veins into the deep veins at the level of the foot, ankle, lower leg, mid leg, behind the knee, lower thigh, mid thigh and upper thigh … The entire system works in harmony and venous harmony means that there is egress of blood out of the lower extremities on a continuous basis. This harmony is assited by breathing and the negative pressure it creates in the chest, essentially ‘sucking’ blood out of the lower extremities. It is also aided by movement and this is where it is important to help this mechanism by developing and maintaining a strong calf muscle pump.
Hratch L Karamanoukian MD FACS RVT RPVI RPhS