In the region from arterial trunks to pial arterioles anatomical characteristics of the cerebral artery as revealed by quantitative treatment of the arterial cast consist in the predominance of the length of large arterial branches over that of the arterioles. Theoretical analysis of blood pressure drop based on the above result demonstrates a large pressure drop in the region of large arterial branches and a relatively insignificant role of the arteriolar region in providing a resistance to cerebral blood flow.
Distinct differences in the evaluated intravascular blood pressure gradient are found among different arterial groups. The medullary artery is characterized by a pronounced pressure drop on account of the extreme length of intramedullary portion, and the blood pressure of medullary capillaries is consequently estimated at a very low level. On the contrary, the blood pressure at the terminal of the cortical artery is presumed to be high and essentially the same irrespective of different routes. The arteries of the basal ganglion divide from large arteries of the cerebral base directly as branches smaller than 300μ in radius. Owing to the small radii an abrupt pressure drop takes place immediately after the arterial entrance into the brain and the blood pressure level at the arteriolar terminal is assumed to attain a level essentially the same as that of cortical arteries in general. The particular pattern of the intravascular blood pressure gradient of the arteries of the basal ganglion is evaluated in association with the predisposition of this part to hypertensive injuries.