The blood supply to the brain has unique and highly relevant characteristics, which are associated with the sensitivity, specialty and importance that nervous tissue has. Among these characteristics, the presence of an arterial circuit located at the base of the brain stands out, from where the blood supply to the brain comes. This circuit has modifications in relation to different groups of vertebrates. According to the morphological model it can be classified into three types (type 1, type 2 and type 3) and according to the phylogenetic model it can be classified into three stages (initial, intermediate and final). Where, when analyzing a sample group of 11 adult animals of the species Bradypus variegatus, it was found that the irrigation of this mammal is supplied by the carotid, rostrally, and basilar, caudally systems, being classified as type 2 alpha, according to the morphological and intermediate classification, in relation to the phylogenetic development model.