Anastomoses and Collateral Circulation: The Body’s Backup System for Blood Flow


Just as an efficient city has multiple routes to ensure consistent traffic flow, our bodies have an intricate network of vessels that carry blood to and from every organ. This redundancy in our vascular system is not only a sign of robust design but also a vital mechanism that ensures the survival of our organs under stress or damage. In this article, we delve into the fascinating world of anastomoses and collateral circulation, and their crucial role in maintaining the body’s circulatory integrity.

The Body’s Backup System for Blood Flow

Anastomoses and Collateral

Understanding Anastomoses and Collateral Circulation

Anastomoses refer to the connection or joining of two blood vessels. This connection can be between arteries, veins, or an artery and a vein. These interconnections form an intricate network throughout the body, providing multiple pathways for blood to reach or leave an organ. Essentially, anastomoses serve as a form of ‘plan B’ for the body’s circulatory system.

Collateral circulation, on the other hand, refers to the alternate or accessory routes through which blood can flow if primary pathways become obstructed. These collateral vessels become particularly essential when the main vessel feeding an organ or draining it is blocked. They ensure that even under such circumstances, the organ continues to receive and drain blood, thereby maintaining its function.

Anatomy of Anastomoses and Collateral Circulation

Various organs in the body are supplied by more than one vessel. For instance, the hand is nourished by both the radial and ulnar arteries. This redundancy means that the loss of either the radial or ulnar artery may not produce any symptoms of reduced blood flow to the hand. This is the body’s way of ensuring uninterrupted service under adverse conditions.

Similarly, venous collaterals, which form when a vein is lost or blocked, can become a lifeline for venous drainage. However, these collaterals can sometimes become susceptible to bleeding. This is a significant problem in patients who have undergone portal vein thrombosis or occlusion, where venous drainage from the gut bypasses the liver through collateral veins to return to the systemic circulation.

Certain organs, such as the duodenum, have a dual blood supply, arising from branches of the celiac trunk and also from the superior mesenteric artery. This redundancy ensures that if either of these vessels is damaged, blood supply will still be maintained to the organ.

Anastomoses and the Brain

The brain, a critical organ with a high demand for oxygen and nutrients, has multiple vessels supplying it, dominated by the carotid arteries and the vertebral arteries. It’s worth noting that vessels within the brain are end arteries and have a relatively poor collateral circulation. This lack of collateral pathways means that any occlusion or blockage can lead to long-term cerebral damage due to the resultant lack of oxygen and nutrient supply, underlining the importance of maintaining good cerebral circulation.


Anastomoses and collateral circulation play a crucial role in the human body’s circulatory system. These networks of vessels form a backup system that ensures blood supply and drainage, even when primary routes are compromised. Understanding these systems is not just important for appreciating the body’s intricate design, but also for managing various medical conditions that can impact blood flow. However, the collateral circulation is not always sufficient to compensate for the loss of major blood vessels, highlighting the importance of maintaining good vascular health.

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