The largest veins in the human body are the venae cavae. These are two large veins which enter the right atrium of the heart from above and below. The superior vena cava carries blood from the arms and head to the right atrium of the heart, while the inferior vena cava carries blood from the legs and abdomen to the heart.
The venules branch into larger veins which eventually carry the blood to the largest veins in the body, the vena cava. Blood is then transported from the superior vena cava and inferior vena cava to the right atrium of the heart. Veins are composed of layers of thin tissue. The vein wall consists of three layers:
It’s a single layer of endothelium cells and some connective tissue. This layer sometimes contains one-way valves, especially in the veins of your arms and legs. These valves prevent blood from flowing backward. Veins are often categorized based on their location and any unique features or functions.