Developed Collateral Networks between the Internal Carotid Artery and External Carotid Artery: Carotid Rete Mirabile.

is a physiological network between the internal carotid artery (ICA) and external carotid artery (ECA) found in lower mammals such as dogs, cats, goats, oxeas, sheep, and pigs. 1,2) CRM is typically located around the cavernous portion of the ICA. CRM supplied by the branches of the ECA compensates for deficient intracranial blood supply and regulates heat and intracranial blood pressure. 1,2) Similar vascular networks between the ICA and ECA can be rarely developed as anastomotic collateral pathways following segmental dysplasia of the ICA in the human. Those anasto-moses between the ICA and ECA resemble morphologically to a rete (net in Latin), and several authors call those anastomotic pathways as carotid rete although those pathological anastomotic collaterals are different from true physi - ological CRM in the lower mammals. Those carotid rete-like collaterals in the human result from the dysplasia of the ICA during the fetal stage. Herein, we present a case of these rare vascular networks supplying a segmental hypoplastic ICA via the ECA