Anatomical description Anatomical description
I Normal anatomy of the paramedian artery: the left and right paramedian arteries arise from their respective posterior cerebral arteries
IIA Variant of the paramedian artery anatomy: both paramedian arteries arise from the left and right posterior cerebral artery
IIB Anatomy of Percheron’s artery: a branch of the right or left PCA supplies the two thalami
III Variant of the paramedian artery anatomy: the two paramedian arteries originate from an arterial branch connecting the D and G ACP