Medial sagittal section illustration of the brain and meninges.

Medial sagittal section illustration of the brain and meninges. The thalamus and hypotalamus are visible as well as the brainstem, cerebral cortex, locus niger, hippocampus and cerebellum. The brain is surrounded by meninges consisting of from the interior to the exterior: the pia mater, arachnoid and dura mater, the sagittal sinus leading to the cerebral veins and the right sinus leading to the cerebral vein gland. The meninges are surrounded by the skull bone. (Photo by: BSIP/Universal Images Group via Getty Images)