Human brain, illustration. Reflection of the dura mater protrudes inward as the falx cerebri in the mid-sagittal plane. The superior sagittal venous sinus (blue) is uppermost with the inferior sinus seen in the lower free margin of the falx cerebri. Venous blood leaves the skull through the internal jugular veins. The anterior cerebral artery (red, from the internal carotid) and branches are shown in proximity to the corpus callosum. From Lizars, J. 1823 A system of anatomical plates of the human body. W.H. Lizars, Edinburgh.