The author stablishes an analogy between the control mechanism and regulation of the cerebral blood flow and of protection of the vascular wall of the internal carotid constituted by the conjunction "internal carotid-cavernous sinus" with the group represented by the system "vertebro basilar-transverse occipital sinus or basilar" (an extension of the cavernous sinus) in the regulation and control of the encephalic circulation carried out through this latter vessels, together with the protection of its vascular walls. The author believes to be very difficult to demonstrate in practice the functionning of these mechanisms, but it is very logical and easy to reason about them, to value them and to give the importance and meaning or motive wich forcibly they should have and not simply consider them as freakes of nature and bizarre anatomical features.