<prompt> Which is least common site of berry aneurysm:Basilar aeryVeebral aeryAnterior cerebral aeryPosterior cerebral aery  <response>: Answer is B Veebral aery: About 85 Harrison to 90 Robbins aneurysms occur in the Anterior circulation, on the circle of Willis. Posterior circulation as inveebral aery is a very uncommon location for berry aneurysm. In order of frequency of occurrence the location of - Anterior communicating - Ant. cerebral junction 29. - Post communicating - Internal carotid junction 28. - Middle cerebral bifurcation 18. - Intracranial carotid bifurcation 8 - Veebrobasilar or basilar bifurcation 3 