Posterior circulation
The posterior cerebral circulation (or simply, posterior circulation) is the blood supply to the posterior portion, including the occipital lobes, cerebellum and brainstem.
The posterior circulation consists of the 2 vertebral artery, basilar artery, 2 posterior cerebral artery, and their branches 1) From these main vessels, many smaller vessels supply the posterior structures of the brain, including:
Posterior inferior cerebellar artery
Anterior inferior cerebellar artery
This is the only vascular region in the body where 2 arteries unite to form a large arterial trunk that again divides in 2 major branches.
Anatomic variants
Fetal circulation: 15–35% of patients supply their posterior cerebral artery on one or both sides primarily from the carotid (via p-comm) instead of via the vertebrobasilar system.
Data indicate that congenital cerebrovascular variants in the posterior circulation and the associated cerebral hypoperfusion may be a factor in triggering arterial hypertension. Therefore, lowering blood pressure may worsen cerebral perfusion in susceptible individuals 2).