Venous flow in the legs consists of superficial “saphenous” and deep “femoral and popliteal” components and their tributaries.
When a person shifts from a horizontal to a vertical position, blood stored in the abdominal and pelvic veins is prevented from “falling” down the leg by rapid closure of functioning valves. |
|
|
Stress is placed on valves by the force of gravity (hydrostatic pressure) and also from episodic pressure increases caused by straining or coughing. Valves lose their integrity resulting in “reflux” or leaking of flow in the opposite direction.
|
|