What is the circle of Willis and why is it important?

The circle of Willis acts to provide collateral blood flow between the anterior and posterior circulations of the brain, protecting against ischemia in the event of vessel disease or damage in one or more areas.

What is posterior communicating artery?

The posterior communicating artery (PCOM) is a part of a group of arteries in the brain known as the circle of Willis. The artery connects the internal carotid and the posterior cerebral arteries. Its role is to provide blood supply to the brain.

What is the circle of Willis in the brain?

The Circle of Willis is the joining area of several arteries at the bottom (inferior) side of the brain. At the Circle of Willis, the internal carotid arteries branch into smaller arteries that supply oxygenated blood to over 80% of the cerebrum.

What is anterior communicating artery?

Anterior communicating artery connects the right and left anterior cerebral arteries. Posteriorly, the basilar artery divides into right and left posterior cerebral arteries and each joins to ipsilateral internal carotid artery through a posterior communicating artery.

What happens when circle of Willis is blocked?

The circle of Willis also serves as a sort of safety mechanism when it comes to blood flow. If a blockage or narrowing slows or prevents the blood flow in a connected artery, the change in pressure can cause blood to flow forward or backward in the circle of Willis to compensate.

Why can the circle of Willis maintain perfusion of the brain even if there is a blockage?

Why can the circle of Willis maintain perfusion of the brain even if there is a blockage in one part of the structure? The nerves that connect the periphery to the CNS pass through these layers of tissue and can be damaged by that inflammation, causing a loss of important neurological functions.

What is AP Comm aneurysm?

Posterior communicating artery (PCOM) aneurysms are one of the most common aneurysms encountered by neurosurgeons and neurointerventional radiologists and are the second most common aneurysms overall (25% of all aneurysms) representing 50% of all internal carotid artery (ICA) aneurysms.

What is a right posterior communicating artery aneurysm?

Posterior communicating artery: Aneurysms present at the junction of the termination of the ICA and PCoA account for 23% of cerebral aneurysms; they are directed laterally, posteriorly, and inferiorly. Pupillary dilatation, ophthalmoplegia, ptosis, mydriasis, and hemiparesis may result.

What percentage of the population has a complete circle of Willis?

Variant anatomy A complete circle of Willis (in which no component is absent or hypoplastic) is only seen in 20-25% of individuals. Posterior circulation anomalies are more common than anterior circulation variants and are seen in nearly 50% of anatomical specimens.

What is the function of the anterior communicating artery?

In case of narrowing of other arteries of the circle of Willis or the arteries supplying the circle, the anterior communicating artery can provide a way to supply blood to the opposite (affected) side of the circle. This can often preserve the cerebral blood supply well enough to avoid the symptoms of ischemia.