Deep veins

The veins of the deep vein system. As the name implies, they lie deep within the tissues between the muscles in the legs, and transport most of the venous blood back to the heart. Valves in the deep veins may be incompetent (leaky) after deep vein thrombosis, for example, or with longstanding severe varicose veins that have not been treated. The result is chronic venous insufficiency (CVI).