Vascularization of the cerebral cortex.

Three levels are described for the study of cortical blood vessels: the mai n leptomeningeal arteries and veins, the fine pial network and the intracor tical vessels. If the main leptomeningeal arteries and veins are well known, the functiona l anatomy of the line cortical blood supply is still obscure. Pial arteries and veins form a dense superficial network. The anastomoses between arteri es and between veins are numerous but no arteriovenous anastomoses were fou nd. Numerous smooth vascular formations are suspected into the vascular wal ls and would regulate the pial (and intracortical) blood flow. The intracortical network is divided into arteries, veins and capillaries. Five types of arteries and veins are described according to their degree of intracortical penetration. The capillary network may be described into fou r layers according to their density. The lay-out of arteries and veins and their branching would allow to suspect three types of intracortical flows. Intracortical vascular units were also described each composed of a central vein surrounded by peripheral arteries. No arterial or venous anastomoses were found in the cortex whereas precapillary arteriovenous shunts would be suspected Vascular deformities may be due to aging, are present in the cor tex and in the subcortical region.