The calf muscle pump is responsible for ejecting what percentage of lower extremity venous volume?

• A. 40%
• B. 50%
• C. 60%
• D. 70%

Answer: (C)

The calf muscle pump plays a crucial role in venous return from the legs to the heart, utilizing the contraction of calf muscles to facilitate the ejection of blood from the veins during physical activity. When the calf muscles contract, they compress the deep veins, propelling blood upwards towards the heart and preventing venous stasis.

Research indicates that the calf muscle pump can effectively eject approximately 60% of the lower extremity venous volume during muscular contraction. This efficient mechanism is vital for maintaining venous return, especially during activities like walking or running, where the muscles are constantly contracting and relaxing. This percentage reflects the significant contribution of the calf muscle pump to the overall circulatory dynamics in the lower extremities, helping to minimize venous pressure and reduce the risk of complications such as venous insufficiency or thrombosis.

The other options do not represent the established physiological understanding of the percentage contribution of the calf muscle pump to venous return.