Do you know about this protective ring inside the brain? (Circle of Willis)

Have you ever thought about how complex and amazingly designed our brain is? For the brain to function properly, it needs a constant supply of oxygen-rich, clean blood. So to do this job properly, the brain has a very amazing safety system. It's like a big roundabout in the middle of a city, helping you to take another road if there's a traffic jam. Today we're talking about this amazing safety system.

What is the Circle of Willis?

Simply put, the Circle of Willis (CoW) is a ring-like structure formed by the blood vessels (arteries) located at the base of our brain, that is, at the bottom. It has a shape like a pentagram. This is the junction that connects the two main blood vessels that supply blood to our brain. Imagine that there are two main blood vessels that bring blood to our brain. 1. Internal Carotid Artery: This is the route that supplies most of the blood to the front of the brain. 2. Vertebral Artery: This is the route that supplies blood to the back of the brain. So, both of these main arteries come together at a roundabout called the Circle of Willis. Due to this, if there is any obstruction or blockage in one artery, blood can be sent to the required area through the other artery. This is like a natural 'fail-safe' system for the safety of our brain. It is named the "Ring of Willis" in honor of the anatomist Thomas Willis, who discovered much about this amazing structure.

Does everyone have this ring?

Here's the amazing thing. According to researchers, less than half of the population has a complete ring of Willis . That means that the majority of people may have small variations, or imperfections, in this ring. Such variations are congenital. These are natural changes that occur when our blood vessels form in the womb. This is neither a disease nor a defect. But, here's the thing. If someone with an incomplete annulus has a condition related to the blood vessels in the brain, such as a stroke , the effects may be a little greater. Because that 'alternative route' or 'detour' we talked about doesn't work properly. This is not something we can change, this is how our body is built.

What is the true significance of the Ring of Willis?

The best way to understand this is to elaborate on the traffic roundabout example we mentioned earlier. Imagine a large roundabout like the one at the Colombo Town Hall. It connects several major roads. Now imagine that there is a major accident on one of the major roads and the road is completely blocked. What happens then? Vehicles coming from other roads can use this roundabout, bypassing the blocked road and get to their destination. The Ring of Willis does exactly this . If a major blood vessel that carries blood to the brain is blocked or damaged, if there is a complete Ring of Willis, the blood coming from the other side can go through this ring and supply blood to the part of the brain that is deprived of blood. This prevents major damage in most cases. Having a complete Ring of Willis can protect you from the severe effects of the following conditions:

What are the chances that a doctor will tell you about this?

Typically, most people will never know they have a ring of Willis until they are diagnosed. However, in some cases, your doctor may tell you about it.

• If you have a brain aneurysm : About 85% of brain aneurysms occur in the Ring of Willis.
• If you have a stroke : A stroke can be caused by a blockage or bleeding in a blood vessel in the Ring of Willis.
• If you have Moyamoya Disease: This is a very rare disease that causes the blood vessels in the Ring of Willis to gradually narrow and become blocked.
• If surgery is required at the base of the brain: For example, when performing surgery on an aneurysm or a pituitary gland tumor, it is very important to avoid damaging the ring of Willis.
• If you have a brain scan : If you have a special test, such as an MRI of the brain or a cerebral angiogram, the report may include information about the nature of your Ring of Willis.

What should we do to keep the Ring of Willis healthy?

As we discussed earlier, we cannot change the structure of the Ring of Willis. It is something that is present at birth. However, there are many things we can do to keep the blood vessels inside that ring healthy and free from blockages. Simply put, we need to control the risk factors that damage the blood vessels in the brain. Let's take a look at what these risk factors are. Controlling these is not only good for your Ring of Willis, but also for your entire body, especially your heart. The best thing to do is to talk to your family doctor about these issues and adjust your lifestyle to suit you. Circle of Willis, blood supply to the brain, stroke, brain aneurysm, blood vessels in the brain, brain structure, anatomy in sinhala