Superior vs Inferior Vena Cava
Superior vena cava and inferior vena cava are collectively known as the ‘venae cavae’. They are considered as the two largest veins that carry deoxygenated blood from lower and upper halves of the body into the heart. Both deliver blood to the right atrium of the heart and are not separated from the right atrium by valves. Venae cavae and aorta form the systemic circuit, which maintain the blood circulation of head, extremities and abdomen.
Superior Vena Cava
Superior vena cava is a large vein which brings deoxygenated blood into the right atrium of the heart from the upper half of the body, including neck, head and upper limbs. It begins above the heart. Superior vena cava is formed by convergence of branchiochephalic veins, which carry blood from the upper limbs, head, and neck, and azygous vein, which carry blood from the thoracic area.
Inferior Vena Cava
Inferior vena cava is the largest vein in the body, which carries deoxygenated blood from the lower half of the body into the right atrium of the heart. It is located posterior to the abdominal cavity and runs to the heart next to the abdominal aorta. Inferior vena cava is formed by the convergence of right and left common iliac veins. This vein is not centrally located; thus there are some asymmetric drainage patterns.
What is the difference between Superior and Inferior Vena Cava?
• Superior vena cava brings deoxygenated blood from the upper limbs, head, and neck, whereas inferior vena cava brings deoxygenated blood from lower limbs, gonads, kidneys and liver.
• Inferior vena cava is larger and longer than superior vena cava (diameter about 2 cm and length about 7 cm).
• Veins draining into the superior vena cava include radial and ulnar veins, brachial vein, axillary vein, cephalic vein, basilica vein, median cubital vein, subclavian vein, external jugular vein, vertebral vein, internal jugular vein and brachiocephalic veins. In contrast, veins draining into the inferior vena cava are anterior and posterior tibial veins, fibular vein, popliteal vein, femoral vein, external iliac vein, great saphenous veins, common iliac vein, external and internal iliac vein, renal vein, hepatic portal vein, and hepatic veins.
• Inferior vena cava begins below the heart, whereas superior vena cava begins above the heart.