What is the primary function of the azygous system?

The primary function of the azygous system is to form linkages between the superior vena cava (SVC) and inferior vena cava (IVC). This system comprises the azygous vein, which runs alongside the vertebral column and serves as a crucial pathway for venous blood returning to the heart from the thoracic structures, particularly when the path through the IVC or SVC is obstructed or not functional.

The azygous system collects blood from the posterior thoracic wall and some abdominal structures, such as the intercostal veins, and routes this blood to the SVC. This capability is essential for maintaining venous return during various physiological conditions, such as pressure changes or certain pathological states.

In contrast to the other options, filtering blood is not a function of the azygous system; this is primarily done by the liver and kidneys. While the liver does receive oxygenated blood, this is via the hepatic artery, not the azygous veins. Lastly, the transport of lymphatic fluid is not related to the azygous system; this function is carried out by the lymphatic vessels and nodes. Thus, the primary role of the azygous system in connecting the major venous return routes makes option