Large blood vessel carrying oxygen-poor to the right atrium from lower half of body?

The large blood vessel carrying oxygen-poor blood to the right atrium from the lower half of the body is the inferior vena cava. The inferior vena cava is one of the two large veins that return deoxygenated blood to the heart. It begins in the abdomen and travels up the right side of the body, entering the right atrium at the top of the heart.