Fig. (4) Cyclostomes. A. Illustration modified after Müller [7] demonstrating the common carotid arteries (CC) traveling from the branchial region to the cranium and then dividing into orbital (Orb) and internal carotid (ICA) arteries. The ICAs join in the midline to form an arteria vertebralis impar (AVI). B, C. Illustrations modified after Sterzi [39] showing the cerebral vessels of the adult lamprey. B. The internal (cerebral) carotid artery (ICA) gives off an ophthalmic (Oph) branch before dividing into anterior (ACCs) and posterior (PCCs) cerebral carotids that enter the braincase separately, just rostral and caudal to the hypophysis. C. The ACCs give off olfactory arteries (Olfs) as well as telencephalic arteries (Tels) to supply the forebrain. The PCCs give off mesencephalic (M) and choroidal (Chr) arteries before continuing caudally as paired basilar arteries (pBA) that give off transverse branches (TAs). Scale bars are 5mm in B and 1mm in C.