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Leg Venous Anatomy and

PhysiologyInteresting Perspectives

John Waites

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Factors Aiding Venous Return• Venous pressure alone is too low to provide adequate blood flow.

• Muscular Pumps: Muscle contraction squeezes the deep veins to propel the venous blood toward the heart. The calf muscles provide most of the pump function. The thigh muscles have a minor effect. Actually compression of the plantar aspect of the foot produces moderate forward venous flow.

• Respiratory Pump: The negative intrathoracic pressure generated during inspiration sucks blood from the arms. BUT, the diaphragm contracts and descends into the abdomen during inspiration, stopping all venous flow and actually pushing back into the legs. Expiration with the upward motion of the relaxing diaphragm produces the negative pressure to suck blood up from the legs.

• Vein Valves prevent backflow during venous return.

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Calf Pump: The contracting calf muscles squeeze the deep veins and

propel the blood up the leg. The closed valves distally prevent the blood from

going backward into the foot.

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Venous Valves are one-way flutter-valves, allowing blood flowing from the feet to the heart to passively

open the two cusps of the valve. When the blood stops flowing and momentarily flows backward (due

to gravity), the valve will close (coapt) within 0.5 sec. When reclining, the valves may remain open.

By convention, the left side is toward the head and the right side of the image is toward the feet.

Open Valve Closed Valve

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No venous valve reflux.

Normal Distal Augmentation.

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Plethysmography

Indicated for diagnosis of calf muscle pump dysfunction.

Measures the change in leg volume in response to

posture and to exercise (toe raises or tip-toe exercise)

A decrease in leg volume with exercise indicates a

normally functioning calf pump which propels the

venous blood proximally back toward the heart.

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W1 Waites,John, 5/29/2017

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Great Saphenous Vein

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