Venous flow in the lower limb veins in the standing position depends upon all except:
A i.e. Aerial blood pressure- In standing position, venous return from the lower limb depends largely on muscular activity, especially contraction of calf and foot muscles, known as muscle pump, whose efficiency is aided by the tight sleeve of deep fascia and valves in perforating veins- In standing position, venous return from leg depends largely on the muscular activity of the triceps surae. The efficiency of calf pump is improved by the deep fascia that invests the muscle like an elastic stocking. The blood is prevented from flowing back in superficial veins by presence of valves in perforating veins. If valves become incompetent the blood is forced into superficial veins during calf muscle contraction and by hydrostatic pressure (of blood column) when straining of standing and these veins become high pressure leaks during muscle contraction leading to varicosity .- Within the closed fascial compament, thin walled, valved deep veins are subjected to intermittent pressure. The pulsation of adjacent aeries and contraction of large muscles within the compament compress these deep veins and force the blood up in limb. Presence of valves in perforating veins prevent backward flowing of blood from high pressure deep veins to low pressure superficial veins. More over as the muscles in closed deep fascial compament relax, venous blood is sucked from superficial into deep veins. - So by this time it must be very clear that venous return in lower limb is dependent on muscle pump, deep fascia, valves in perforators, and pulsation of adjacent aeriesQ- Blood flow in blood vessels including veins is primarily because of pumping action of hea. However, venous flow is aided by hea beat (in great veins draining into atrium), the increase in negative intrathoracic pressure (especially in great veins, intrathoracic & intraabdominal veins), and muscle pump (lower limb veins).
Aerial blood pressure
Presence of deep facial planes
Compression of calf muscles
Presence of perforators