Editing Ventricular system (section)

=== Flow of cerebrospinal fluid ===
[[File:NPH MRI 272 GILD.gif|thumb|left|MRI showing flow of CSF]]The ventricles are filled with [[cerebrospinal fluid]] (CSF) which bathes and cushions the brain and [[spinal cord]] within their bony confines. CSF is produced by modified [[ependymal cell]]s of the [[choroid plexus]] found in all components of the ventricular system except for the [[cerebral aqueduct]] and the [[Lateral ventricles|posterior]] and [[Lateral ventricles|anterior horns]] of the [[lateral ventricles]]. CSF flows from the lateral ventricles via the [[Interventricular foramina (neural anatomy)|interventricular foramina]] into the [[third ventricle]], and then the [[fourth ventricle]] via the [[cerebral aqueduct]] in the [[midbrain]]. From the fourth ventricle it can pass into the [[central canal]] of the [[spinal cord]] or into the [[subarachnoid cisterns]] via three small foramina: the central [[median aperture]] and the two [[lateral aperture]]s.
According to the traditional understanding of cerebrospinal fluid (CSF) physiology, the majority of CSF is produced by the choroid plexus, circulates through the ventricles, the cisterns, and the subarachnoid space to be absorbed into the blood by the arachnoid villi.{{cn|date=January 2024}}

The fluid then flows around the [[superior sagittal sinus]] to be reabsorbed via the [[arachnoid granulation]]s  (or arachnoid villi) into the [[venous sinuses]], after which it passes through the [[jugular vein]] and major [[venous system]]. CSF within the spinal cord can flow all the way down to the [[cistern (neuroanatomy)|lumbar cistern]] at the end of the cord around the [[cauda equina]] where [[lumbar puncture]]s are performed.

The [[cerebral aqueduct]] between the [[third ventricle|third]] and [[fourth ventricle]]s is very small, as are the foramina, which means that they can be easily blocked.