The cerebral arterial circulation at the base of the brain is diagrammed here. A berry aneurysm is diagrammed at the final bifurcation of the right internal carotid artery. The most common locations for berry aneurysms are in the region of the anterior communicating and anterior cerebral, at the trifurcation of the middle cerebral, and at the bifurcation of internal carotid with posterior communicating. Vertebral-basilar aneurysms comprise <10% of cases. Multiple aneurysms occur in about 20 to 30% of cases.
AbbrName of ArteryDistribution
ACAAnterior Cerebral ArterySupplies most medial portions of frontal lobes and superior medial parietal lobes
AComAAnterior Communicating ArteryConnects the anterior cerebral arteries at their closest juncture
ICAInternal Carotid ArteryAscends through base of skull to give rise to the anterior and middle cerebral arteries, and connect with posterior half of circle of Willis via posterior communicating artery
MCAMiddle Cerebral ArteryTrifurcates into temporal, frontal, and parietal branches that supply most of the parenchyma of these lobes
PComAPosterior Communicating ArteryConnects the anterior circle of Willis with the posterior cerebral artery of vertebral-basilar circulation posteriorly
PCAPosterior Cerebral ArterySupplies the occipital lobe and the inferior portion of temporal lobe. A branch supplies the choroid plexus.
SCASuperior Cerebellar ArterySupplies the dorsal cerebellum, pons, and midbrain
BABasilar ArteryFormed by the junction of the two vertebral arteries, it terminates as a bifurcation into the posterior cerebral arteries
AICAAnterior Inferior Cerebellar ArterySupplies the inferior cerebellum and portions of pons and medulla
VAVertebral ArteryThe vertebrals emerge from the posterior base of skull and merge to form the basilar artery
PICAPosterior Inferior Cerebellar ArterySupplies the posterior cerebellum, choroid plexus in 4th ventricle, and portions of medulla
ASAAnterior Spinal ArteryDescends along the anterior (ventral) aspect of the spinal cord