What vein brings blood from below the diaphragm to the heart?

The vein that brings blood from below the diaphragm to the heart is the inferior vena cava. This large vein plays a critical role in the circulatory system by collecting deoxygenated blood from the lower parts of the body, including the abdomen, pelvis, and legs. It then transports this blood upwards to the right atrium of the heart.

The inferior vena cava receives blood from various smaller veins as well, making it essential for returning blood to the heart after it has circulated through the body's lower regions. This process ensures that all blood eventually makes its way back to the heart to be reoxygenated by passing through the lungs.

The other listed veins serve different functions and areas of the body. The subclavian vein primarily carries blood from the arms and shoulders back to the heart. The jugular vein is responsible for draining blood from the head and neck. The femoral vein is involved in draining blood from the upper leg. Therefore, while all these veins are vital to the circulatory system, only the inferior vena cava is specifically tasked with returning blood from below the diaphragm.