Relationship between Intracranial and Extracranial Parts of Cephalic Circulation

Abstract

Simultaneous measurement of both the internal and the external carotid blood flows was taken with photoelectric drop-recorders in unanesthetized rabbits. 1) The reciprocal relationship was found between the internal carotid blood flow and the external carotid one. The internal carotid blood flow was moderately increased when the external carotid blood flow was reduced by more than thirty per cent. However, the former was only slightly decreased even when the latter was twicely increased. 2) The passive changes in blood flow following the changes in the systemic blood pressure were less remarkable in the internal carotid artery than in the external carotid artery.