Brain with focus on cerebrospinal fluid, sagittal section

Anatomically, the model shows, via a sagittal section through the brain and skull, how the cerebrospinal fluid is found in the ventricular system and the subarachnoid space.



Surrounding the brain are the three meninges, which from innermost to outermost are:



Pia mater - marked in red
Arachnoidea mater - marked with pink
Dura mater - marked in gray


Between the pia mater and the arachnoid mater is the subarachnoid space.



The brain's ventricular system, where the cerebrospinal fluid is produced, is also seen. This consists of four cavities, all of which are filled with cerebrospinal fluid:



The lateral ventricles - of these there are two, one in each hemisphere
Third ventricle - found in the midbrain (diencephalon)
Fourth ventricle - (located between the brainstem and the cerebellum)


The transition between the ventricular system and the subarachnoid space is found in the fourth ventricle. Therefore, all the cerebrospinal fluid that is in the lateral ventricles and third ventricle will flow here first.



Beyond the fourth ventricle, an expansion of the subarachnoid space (cisterna cerebellomedullaris) is seen, into which the cerebrospinal fluid is emptied through holes in the wall of the fourth ventricle. From here, the fluid is distributed in the rest of the subarachnoid space, which surrounds both the brain and the spinal cord.



From the subarachnoid space, the cerebrospinal fluid drains into the venous system.