Venous territories of the brain.

The venous return of the cerebral hemispheres is ensured by two systems. The first, superficial system, reaches the peripheral dural sinuses, i.e. the superior sagittal sinus, the lateral sinus and the cavernous sinus. The second, deep system, corresponds to Galen's vein. Anatomical and angiographic data from the literature enable the usual drainage territory to be defined for each of these collecting vessels. However, the variability of the superficial sylvian vein and the importance of cortical anastomotic vessels make impossible to delimit precisely the territory of each peripheral sinus. The functional role played by numerous centro-peripheral anastomoses is more difficult to assert in each individual. It is therefore probable that in the cerebral hemispheres there is a deep territory balancing the superficial territories.