Which statement about venous drainage to the heart is correct?

• A. Veins drain oxygenated blood toward the heart.
• B. The cranial vena cava drains blood from the hind limbs.
• C. Veins have thicker walls than arteries.
• D. The cranial vena cava drains deoxygenated blood from the head and neck, while the caudal vena cava drains the remainder of the body.

Answer: (D)

Blood returning to the heart from the body is carried by veins, and in the systemic circuit this blood is deoxygenated. The cranial vena cava collects blood from the head, neck, and forelimbs, while the caudal vena cava collects blood from the rest of the body, including the hind limbs, abdomen, and pelvis. So the statement matching these drainage patterns is correct. It’s not true that systemic veins carry oxygenated blood toward the heart, and the hind limbs drain via the caudal vena cava, not the cranial. Also, veins have thinner walls than arteries, not thicker. (An occasional exception to note: pulmonary veins return oxygenated blood from the lungs to the left heart.)