<prompt> The least common site for a berry aneurysm is -Vertebral arteryBasilar arteryJunction of anterior cerebral artery and internal carotid arteryPosterior cerebral artery  <response>: A berry aneurysmThe further away the aneurysm from the anterior circulation or from the circle of willis , the less common will be its rate of occurance.Berry an aneurysm or Saccular aneurysm or Congenital aneurysm is the most frequent type of intracranial aneurysm.Most aneurysms occur in the anterior circulation and are found near the branch points.The most common site is junction between anterior cerebral artery and anterior communication artery 40.Next most common site is internal carotid artery and posterior communicating artery 20Less frequent sites include -Top of basilar arteryJunction of basilar artery and the superior cerebllar artery or anterior inferior cerebellar artery.Junction of vertebral artery and posterior inferior cerebellar artery. 