Difference Between Superior and Inferior Vena Cava

The main difference between superior and inferior vena cava is that the superior vena cava drains blood from the upper part of the body while the inferior vena cava drains blood from the lower part of the body. Furthermore, superior vena cava drains blood from the head, neck, arms, and the upper chest wall while inferior vena cava drains blood from the legs, pelvis, and abdomen.

Superior and inferior vena cava are the two main veins of the body that drain deoxygenated blood back to the heart.

Key Areas Covered

1. What is Superior Vena Cava
     – Definition, Anatomy, Function
2. What is Inferior Vena Cava
     – Definition, Anatomy, Function
3. What are the Similarities Between Superior and Inferior Vena Cava
     – Outline of Common Features
4. What is the Difference Between Superior and Inferior Vena Cava
     – Comparison of Key Differences

Key Terms

Brachiocephalic Veins, Deoxygenated Blood, Iliac Veins, Inferior Vena Cava (IVC), Right Atrium, Superior Vena Cava (SVC)

What is Superior Vena Cava

Superior vena cava (SVC) is one of the two main types of veins in the body that transports deoxygenated blood from the upper part of the body to the right atrium of the heart. It is located in the anterior right superior mediastinum. The left and the right brachiocephalic veins forms the superior vena cava.

Figure 1: Superior and Inferior Vena Cava

The constriction or obstruction of the superior vena cava is known as superior vena cava syndrome. The constriction can occur due to the enlargement of surrounding tissue such as thyroid, thymus, aorta, lymph nodes or the cancerous tissue in the lungs or the chest. The obstruction or swelling of the superior vena cava can slower the blood flow.

What is Inferior Vena Cava

Inferior vena cava is the largest vein in the body and drains deoxygenated blood from the lower parts of the body to the right atrium of the heart. It is formed by the joining of the left and the right iliac veins. Its formation occurs in the superior end of the pelvic cavity and this vein ascends through the posterior abdominal body wall to the right of the vertebral column. Ultimately, it connects to the heart from the posterior side of the right atrium, inferior to the superior vena cava.

Figure 2: Superior and Inferior Vena Cava Location

The obstruction or compression of the inferior vena cava causes inferior vena cava syndrome. Congestive heart failure, kidney disease, deep vein thrombosis, tumors or pregnancy can lead to inferior vena cava syndrome.

Similarities Between Superior and Inferior Vena Cava

• Superior and inferior vena cava are the two main types of veins in the body.
• They have a thin wall and a wide lumen.
• They drain deoxygenated blood from the body to the heart.
• Both supply blood to the right atrium.
• Since both types of veins carry blood against the gravity, they contain valves that prevent the backflow of the blood.
• The pressure of the blood inside each vena cava is low.
• Muscular contractions are the driving force of the blood inside the vena cava.

Difference Between Superior and Inferior Vena Cava

Definition

Superior vena cava refers to a large vein that receives blood from the head, neck, upper extremities, and thorax and delivers it to the right atrium of the heart. The inferior vena cava refers to a large vein that receives blood from the lower extremities, pelvis, and abdomen and delivers it to the right atrium of the heart.

The difference between superior and inferior vena cava is thus self explanatory from the above definitions. However, there are some more differences between superior and inferior vena cava as detailed below.

Location

Superior vena cava is located in the anterior right superior mediastinum while inferior vena cava is located in posterior to the abdominal cavity, alongside to the right vertebral column.

Length

The superior vena cava is a short vein while the inferior vena cava is long.

Diameter

The diameter of the superior vena cava is 18-22 mm while the diameter of the inferior vena cava is 27-36 mm.

Parts of the Body

Superior vena cava drains blood from the upper parts of the body while inferior vena cava drains blood from the lower parts of the body.

Types of Veins Draining

Some of the veins that drain into the superior vena cava are radial and ulnar veins, cephalic, basilic, median cubital, brachial, axillary, subclavian, and internal and external jugular veins while the tributaries of the inferior vena cava are the hepatic veins, inferior phrenic vein, right suprarenal vein, renal veins, right gonadal veins, lumbar veins, and common iliac veins.

Conclusion

Superior vena cava is the second largest vein of the body, which drains deoxygenated blood from the upper part of the body to the right atrium of the heart. Further, inferior vena cava is the largest vein of the body, which drains deoxygenated blood from the upper part of the body to the right atrium. The main difference between superior and inferior vena cava is the position and the part of the body from which they drain blood.

Reference:

1. “Superior Vena Cava.” Kenhub, Available Here
2. “Inferior Vena Cava – Anatomy Pictures and Information.” InnerBody, Available Here

Image Courtesy:

1. “Diagram of the human heart (cropped)” By Wapcaplet – Own work (CC BY-SA 3.0) via Commons Wikimedia  
2. “2132 Thoracic Abdominal Veins” By OpenStax College – Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia