What is the primary driving force of lower extremity venous flow?

The primary driving force of lower extremity venous flow is the musculovenous pump. This phenomenon occurs when the skeletal muscles, particularly those in the legs, contract during activities like walking or running. As the muscles contract, they compress the veins located within and between the muscle groups. This compression pushes the blood in the veins upwards toward the heart, effectively promoting venous return.

Additionally, the presence of one-way venous valves prevents the backflow of blood, ensuring that it moves in the correct direction. The musculovenous pump is particularly crucial in the lower extremities because gravity acts against venous return when a person is standing or sitting, making the muscle contractions essential for maintaining adequate blood flow back to the heart. The ability of this pump to facilitate effective venous return is vital for preventing venous stasis and its associated complications, such as venous thromboembolism.

Other factors, such as external compression from surrounding tissue and arterial inflow, do play roles in the overall hemodynamics of the body, but they do not primarily drive venous flow in the lower extremity the way the musculovenous pump does.