sagittal sinus

:  either of two venous sinuses of the dura mater:a:  one passing backward in the convex attached superior margin of the falx cerebri and ending at the internal occipital protuberance by fusion with the transverse sinus—called also superior sagittal sinusb:  one lying in the posterior two thirds of the concave free inferior margin of the falx cerebri and ending posteriorly by joining the great cerebral vein to form the straight sinus—called also inferior sagittal sinus