The superior vena cava is a large vein in the human body that carries deoxygenated blood from the upper half of the body to the heart. It collects blood from areas such as the head, neck, arms, and upper chest, ensuring that this blood returns to the heart for reoxygenation. Located near the right atrium of the heart, the superior vena cava is crucial for maintaining proper blood circulation. It works alongside the inferior vena cava, which carries blood from the lower body, to ensure that all deoxygenated blood is efficiently returned to the heart for oxygenation.