Illustration of the base of the cerebrum and cerebellum of the brain. Flanking the centrally located optic chiasm, the internal carotid arteries are shown cut. Branches passing forward are the anterior cerebral arteries with the left and right middle cerebral arteries extending laterally. Inferiorly the vertebral arteries merge forming the basilar artery near to the pons. Posterior cerebral and cerebellar arteries arise from the basilar artery. Cerebral and cerebellar veins (blue) are shown. From Lizars, J. 1823 A system of anatomical plates of the human body. W.H. Lizars, Edinburgh.