 Hello everyone, welcome back to another session in dentistry ammo. Today we have a small topic in human anatomy that is circle of Willis Circle of Willis, it is a commonly asked shot knot in university exams So as the picture says it is a an asthmatic ring of Art trees which is seen in brain. So let's get into details of circle of Willis So circle of Willis It is also known as cerebral arterial circle or Circulus arteriosus So cerebral arterial circle or Circulus arteriosus. It is the Anastomotic ring of our trees located at the base of the brain This arterial an asthmatic circle which connects the two major arterial systems to the brain. That is an internal carotid arteries Internal carotid arteries and the vertebro basilar system. So this is vertebral artery and this is a basilar artery So it connects two system that is internal carotid arteries and the vertebro basilar Systems and it is formed by four paired vessels and a single unpaired vessel With numerous branches that supply the brain So let's see the arteries from anterior to posterior so the paired arteries are Anterior cerebellar artery we have two arteries left and right And the unpaired artery is anterior communicating artery So this is the anterior communicating artery which is an unpaired one So anterior cerebellar artery is a paired one. We have right and left then internal carotid artery. We have Left and right, which is also paired Posterior cerebellar artery. So posterior cerebellar arteries here This also we have paired left and right and Posterior communicating artery again. We have right and left. Okay, so Anterior cerebellar artery internal carotid artery posterior cerebellar artery posterior communicating artery are the paired arteries and Anterior communicating artery is a unpaired artery. So these Forms a circle which is known as circle of will is the middle cerebral artery. So the middle cerebral arteries They actually supply the brain, but are not considered part of circle of will is And also we have various other arteries like basilar artery superior cerebellar artery Anterior inferior cerebellar artery posterior inferior cerebellar artery vertebral artery But circle of will is has these arteries. That means four paired arteries on one and paired arteries. Okay So what is the main function of circle of will is so circle of will is is to provide a collateral blood flow between the anterior and posterior arterial system of brain, okay So it is to provide a collateral blood flow between anterior and posterior arterial systems of brain in addition to that it offers the alternate blood flow pathways between the right and Left cerebral hemispheres it provides a alternate blood flow pathway between right and left Cerebral hemispheres. So this way the circle protects the brain from ischemia and stroke in cases of vascular obstruction or damage So this circle provides the alternate blood flow pathway to right and left hemispheres so it can prevent the Arterial problems such as ischemia and stroke When there is vascular obstruction or damage happens in the any of the arterial system so I discussed about the components of circle of will is and its function and Circle of will is Which is named after a English physician? Thomas will is so So the circle of will is Allows blood to flow across the midline of the brain if an artery on one side is occluded And the circle of will is thereby serves a safety valve function for the brain Allowing collateral circulation or flow of blood through an alternate route to take place if the flow is reduced one area So this is a mechanism. I have a safety valve mechanism which is seen Inside the arteries of brain So that's about a circle of will is which is having four pairs of artery and one unpaired artery So anterior cerebellar artery internal carotid artery posterior communicating and posterior cerebellar artery are the paired arteries and anterior communicating artery is Unpaired one it is cerebral artery is not Part of this circle. So this is actually The circle of will is So don't get confused. So this is the Circle of will is Circle of will is So it is an important question Frequently asked in university XMS a shop not so you need to draw the diagram and mark the five arteries and write about its Two or three functions. That is the safety valve mechanism and helps in ischemia and the stroke So I'll come up with a new topic in anatomy. Thank you