<P> The anterior and posterior cerebral circulations are interconnected via bilateral posterior communicating arteries . They are part of the Circle of Willis, which provides backup circulation to the brain . In case one of the supply arteries is occluded, the Circle of Willis provides interconnections between the anterior and the posterior cerebral circulation along the floor of the cerebral vault, providing blood to tissues that would otherwise become ischemic . </P> <P> The anterior cerebral circulation is the blood supply to the anterior portion of the brain . It is supplied by the following arteries: </P> <Ul> <Li> Internal carotid arteries: These large arteries are the medial branches of the common carotid arteries in the neck which enter the skull, as opposed to the external carotid branches which supply the facial tissues . The internal carotid artery branches into the anterior cerebral artery and continues to form the middle cerebral artery </Li> <Li> Anterior cerebral artery (ACA) <Ul> <Li> Anterior communicating artery: Connects both anterior cerebral arteries, within and along the floor of the cerebral vault . </Li> </Ul> </Li> <Li> Middle cerebral artery (MCA) </Li> </Ul> <Li> Internal carotid arteries: These large arteries are the medial branches of the common carotid arteries in the neck which enter the skull, as opposed to the external carotid branches which supply the facial tissues . The internal carotid artery branches into the anterior cerebral artery and continues to form the middle cerebral artery </Li>

4 arteries that supply blood to the brain