Which is least common site of berry aneurysm:
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%)
Basilar aery
Veebral aery
Anterior cerebral aery
Posterior cerebral aery