Editing Ventricular system

{{Short description|Structures containing cerebrospinal fluid}}
{{Infobox brain
| Name            = Ventricular system
| Latin           = ventriculi cerebri
| Image           = Brain-ventricle-anatomy-diagram.jpg
| Caption         = Ventricular system anatomy
| Image2          = Human ventricular system - animation.gif
| Caption2        = Rotating 3D rendering of the four ventricles and connections
| IsPartOf        =
| Components      =
| Artery          =
| Vein            =
}}

In [[neuroanatomy]], the '''ventricular system''' is a set of four interconnected cavities known as '''cerebral ventricles''' in the [[brain]].<ref name="Grow 2018 pp. 72–90.e1">{{cite book | last=Grow | first=W.A. | title=Fundamental Neuroscience for Basic and Clinical Applications | chapter=Development of the Nervous System | publisher=Elsevier | year=2018 | isbn=978-0-323-39632-5 | doi=10.1016/b978-0-323-39632-5.00005-0 | pages=72–90.e1 | quote=The ventricular system is an elaboration of the lumen of cephalic portions of the neural tube, and its development parallels that of the brain.}}</ref><ref name="Shoykhet Clark 2011 pp. 783–804">{{cite book | last1=Shoykhet | first1=Mish | last2=Clark | first2=Robert S.B. | title=Pediatric Critical Care | chapter=Structure, Function, and Development of the Nervous System | publisher=Elsevier | year=2011 | isbn=978-0-323-07307-3 | doi=10.1016/b978-0-323-07307-3.10057-6 | pages=783–804 | quote=The ventricles contain the choroid plexus, which produces CSF, and serve as conduits for CSF flow in the CNS. Ventricular walls are lined with ependymal cells, which are connected by tight junctions and constitute a CSF-brain barrier.}}</ref> Within each ventricle is a region of [[choroid plexus]] which produces the circulating [[cerebrospinal fluid]] (CSF). The ventricular system is continuous with the [[central canal]] of the [[spinal cord]] from the fourth ventricle,<ref name="Shoykhet Clark 2011 pp. 783–804 II">{{cite book | last1=Shoykhet | first1=Mish | last2=Clark | first2=Robert S.B. | title=Pediatric Critical Care | chapter=Structure, Function, and Development of the Nervous System | publisher=Elsevier | year=2011 | isbn=978-0-323-07307-3 | doi=10.1016/b978-0-323-07307-3.10057-6 | pages=783–804 | quote=The ventricular system arises from the hollow space within the developing neural tube and gives rise to cisterns within the CNS, from the brain to the spinal cord. }}</ref> allowing for the flow of CSF to circulate.<ref name="Shoykhet Clark 2011 pp. 783–804 II"/><ref name="Vernau Vernau Sue Bailey 2008 pp. 769–819">{{cite book | last1=Vernau | first1=William | last2=Vernau | first2=Karen A. | last3=Sue Bailey | first3=Cleta | title=Clinical Biochemistry of Domestic Animals | chapter=Cerebrospinal Fluid | publisher=Elsevier | year=2008 | isbn=978-0-12-370491-7 | doi=10.1016/b978-0-12-370491-7.00026-x | pages=769–819 | s2cid=71013935 | quote=Cerebrospinal fluid flows in bulk from sites of production to sites of absorption. Fluid formed in the lateral ventricles flows through the paired interventricular foramina (foramen of Monro) into the third ventricle, then through the mesencephalic aqueduct (aqueduct of Sylvius) into the fourth ventricle. The majority of CSF exits from the fourth ventricle into the subarachnoid space; a small amount may enter the central canal of the spinal cord. }}</ref>

All of the ventricular system and the central canal of the spinal cord are lined with [[ependyma]], a specialised form of [[epithelium]] connected by [[tight junction]]s that make up the [[Choroid plexus#Blood–cerebrospinal fluid barrier|blood–cerebrospinal fluid barrier]].<ref name="Shoykhet Clark 2011 pp. 783–804"/>

== Structure ==
[[File:Blausen 0896 Ventricles Brain.png|thumb|left|3D rendering of ventricles (lateral and anterior views)]]

The system comprises four ventricles:<ref name="Openstax Anatomy & Physiology attribution">{{CC-notice|cc=by4|url=https://openstax.org/books/anatomy-and-physiology/pages/13-3-circulation-and-the-central-nervous-system}} {{cite book|last1=Betts|first1=J Gordon|last2=Desaix|first2=Peter|last3=Johnson|first3=Eddie|last4=Johnson|first4=Jody E|last5=Korol|first5=Oksana|last6=Kruse|first6=Dean|last7=Poe|first7=Brandon|last8=Wise|first8=James|last9=Womble|first9=Mark D|last10=Young|first10=Kelly A|title=Anatomy & Physiology|location=Houston|publisher=OpenStax CNX|isbn=978-1-947172-04-3|date=July 16, 2023|at=13.3 Circulation and the Central Nervous System}}</ref>
* [[lateral ventricles]] right and left (one for each hemisphere)
* [[third ventricle]]
* [[fourth ventricle]]

There are several [[foramina]], openings acting as channels, that connect the ventricles. The interventricular foramina (also called the foramina of Monro) connect the lateral ventricles to the third ventricle through which the cerebrospinal fluid can flow.

{| class="wikitable"
! Name !! From !! To
|-
| [[Interventricular foramina (neural anatomy)|interventricular foramina]] (Monro) || lateral ventricles  || third ventricle
|-
| [[Cerebral aqueduct]] (Sylvius) || third ventricle || fourth ventricle
|-
| [[Median aperture]] (Magendie) || fourth ventricle || [[subarachnoid space]] via the [[cisterna magna]]
|-
| Right and left [[lateral aperture]]s (Luschka) || fourth ventricle || subarachnoid space via the [[cistern of great cerebral vein]]
|}

=== Ventricles ===
The four cavities of the human brain are called ventricles.<ref>{{cite web | url=https://www.nlm.nih.gov/medlineplus/ency/imagepages/9567.htm | title =Ventricles of the brain | author =National Institutes of Health | author-link =National Institutes of Health | publisher =nih.gov | date =December 13, 2011}}</ref> The two largest are the lateral ventricles in the cerebrum, the third ventricle is in the diencephalon of the forebrain between the right and left thalamus, and the fourth ventricle is located at the back of the pons and upper half of the [[medulla oblongata]] of the hindbrain. The ventricles are concerned with the production and circulation of [[cerebrospinal fluid]].<ref>International school of medicine and applied sciences kisumu library</ref>

=== Development === <!--Development of ventricular system redirects here-->
The structures of the ventricular system are [[embryogenesis|embryologically]] derived from the [[neural canal]], the centre of the [[neural tube]].{{cn|date=January 2024}}

As the part of the primitive neural tube that will develop into the [[brainstem]], the neural canal expands dorsally and laterally, creating the [[fourth ventricle]], whereas the neural canal that does not expand and remains the same at the level of the midbrain superior to the fourth ventricle forms the [[cerebral aqueduct]]. The fourth ventricle narrows at the [[obex]] (in the caudal medulla), to become the [[central canal]] of the [[spinal cord]].{{cn|date=January 2024}}

In more detail, around the third week of development, the embryo is a three-layered disc. The embryo is covered on the [[:wikt:dorsal|dorsal]] surface by a layer of cells called [[ectoderm]]. In the middle of the dorsal surface of the embryo is a linear structure called the [[notochord]]. As the ectoderm proliferates, the notochord is dragged into the middle of the developing embryo.<ref name=LARSEN2009>{{cite book|first=Gary C. |last=Schoenwolf|title=Larsen's human embryology|year=2009|publisher=Churchill Livingstone/Elsevier|location=Philadelphia|isbn=9780443068119|chapter="Development of the Brain and Cranial Nerves"|edition=4th}}</ref>

As the [[Brain#Development|brain develops]], by the fourth week of embryological development three swellings known as [[brain vesicle]]s have formed within the embryo around the canal, near where the head will develop. The three primary brain vesicles represent different components of the [[central nervous system]]: the [[prosencephalon]], [[mesencephalon]] and [[rhombencephalon]]. These in turn divide into five secondary vesicles. As these sections develop around the neural canal, the inner neural canal becomes known as ''primitive'' ventricles. These form the ventricular system of the brain:<ref name=LARSEN2009 />  The [[neural stem cells]] of the developing brain, principally [[radial glial cell]]s, line the developing ventricular system in a transient zone called the [[ventricular zone]].<ref>{{cite journal|last1=Rakic|first1=P|title=Evolution of the neocortex: a perspective from developmental biology.|journal=Nature Reviews. Neuroscience|date=October 2009|volume=10|issue=10|pages=724–35|pmid=19763105|doi=10.1038/nrn2719|pmc=2913577}}</ref>
* The [[prosencephalon]] divides into the [[telencephalon]], which forms the [[cerebral cortex|cortex]] of the developed brain, and the [[diencephalon]]. The ventricles contained within the telencephalon become the [[lateral ventricles]], and the ventricles within the [[diencephalon]] become the [[third ventricle]].
* The rhombencephalon divides into a [[metencephalon]] and [[myelencephalon]]. The ventricles contained within the rhombencephalon become the [[fourth ventricle]], and the ventricles contained within the mesencephalon become the [[aqueduct of Sylvius]].

Separating the anterior horns of the lateral ventricles is the [[septum pellucidum]]: a thin, triangular, vertical membrane which runs as a sheet from the [[corpus callosum]] down to the [[fornix of the brain|fornix]]. During the third month of fetal development, a space forms between two septal laminae, known as the [[cave of septum pellucidum]] (CSP), which is a marker for fetal neural maldevelopment. During the fifth month of development, the laminae start to close and this closure completes from about three to six months after birth. Fusion of the septal laminae is attributed to rapid development of the [[Alveus of hippocampus|alvei]] of the [[hippocampus]], [[amygdala]], [[septal nuclei]], fornix, corpus callosum and other midline structures. Lack of such limbic development interrupts this posterior-to-anterior fusion, resulting in the continuation of the CSP into adulthood.<ref name="Adrian Raine 2010 p.110">{{cite journal | last1 = Raine | first1 = Adrian | last2 = Lee | first2 = Lydia | last3 = Yang | first3 = Yaling | last4 = Colletti | first4 = Patrick | year = 2010 | title = Neurodevelopmental marker for limbic maldevelopment in antisocial personality disorder and psychopathy". BJPsych | journal = The British Journal of Psychiatry | volume = 197 | issue = 3| pages = 186–192 | doi = 10.1192/bjp.bp.110.078485 | pmid=20807962 | pmc=2930915}}</ref>

== Function ==

=== 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.

=== Protection of the brain ===
The brain and spinal cord are covered by the [[meninges]], the three protective membranes of the tough [[dura mater]], the [[arachnoid mater]] and the [[pia mater]]. The cerebrospinal fluid (CSF) within the [[skull]] and spine provides further protection and also [[buoyancy]], and is found in the [[subarachnoid space]] between the pia mater and the arachnoid mater.{{cn|date=January 2024}}

The CSF that is produced in the ventricular system is also necessary for chemical stability, and the provision of nutrients needed by the brain. The CSF helps to protect the brain from jolts and knocks to the head and also provides buoyancy and support to the brain against gravity. (Since the brain and CSF are similar in density, the brain floats in neutral buoyancy, suspended in the CSF.) This allows the brain to grow in size and weight without resting on the floor of the cranium, which would destroy nervous tissue.<ref>Klein, S.B., & Thorne, B.M. Biological Psychology. Worth Publishers: New York. 2007.</ref><ref>Saladin, Kenneth S. Anatomy & Physiology. The Unit of Form and Function. 5th Edition. McGraw-Hill: New York. 2007</ref>

== Clinical significance ==
The narrowness of the cerebral aqueduct and foramina means that they can become blocked, for example, by blood following a hemorrhagic stroke. As cerebrospinal fluid is continually produced by the choroid plexus within the ventricles, a blockage of outflow leads to increasingly high pressure in the [[lateral ventricle]]s. As a consequence, this commonly leads in turn to [[Hydrocephalus#Noncommunicating|hydrocephalus]]. Medically one would call this post-haemorrhagic acquired hydrocephalus, but is often referred to colloquially by the layperson as "water on the brain". This is an extremely serious condition regardless of the cause of blockage. An [[endoscopic third ventriculostomy]] is a surgical procedure for the treatment of hydrocephalus in which an opening is created in the floor of the [[third ventricle]] using an [[endoscope]] placed within the ventricular system through a [[burr hole]]. This allows the [[cerebrospinal fluid]] to flow directly to the [[basal cisternae|basal cisterns]], thereby bypassing any obstruction. A surgical procedure to make an entry hole to access any of the ventricles is called a [[ventriculostomy]]. This is done to drain accumulated cerebrospinal fluid either through a temporary catheter or a permanent shunt.{{cn|date=January 2024}}

Other diseases of the ventricular system include inflammation of the membranes ([[meningitis]]) or of the ventricles ([[ventriculitis]]) caused by [[infection]] or the introduction of [[blood]] following trauma or [[haemorrhage]] ([[cerebral haemorrhage]] or [[subarachnoid haemorrhage]]).

During [[embryogenesis]] in the [[choroid plexus]] of the ventricles, [[choroid plexus cysts]] can form.

The [[scientific method|scientific]] study of [[Computed tomography|CT scan]]s of the ventricles in the late 1970s gave new insight into the study of [[mental disorder]]s.  Researchers found that individuals with [[schizophrenia]] had (in terms of group averages) larger than usual ventricles. This became the first "evidence" that schizophrenia was [[Biology|biological]] in origin and led to a renewed interest in its study via the use of [[Imaging technology|imaging techniques]]. [[Magnetic resonance imaging]] (MRI) has superseded the use of CT in research in the role of detecting ventricular abnormalities in psychiatric illness.

Whether enlarged ventricles is a cause or a result of schizophrenia has not yet been established. Enlarged ventricles are also found in organic [[dementia]] and have been explained largely in terms of environmental factors.<ref name=Peper2007>{{Cite journal | last1 = Peper | first1 =  Jiska S. | year = 2007 | title = Genetic influences on human brain structure: A review of brain imaging studies in twins | journal = Human Brain Mapping | volume = 28 | pages = 464–73 | doi = 10.1002/hbm.20398 | pmid = 17415783 | last2 = Brouwer | first2 = RM | last3 = Boomsma | first3 = DI | last4 = Kahn | first4 = RS | last5 = Hulshoff Pol | first5 = HE | issue = 6| pmc = 6871295 }}</ref> They have also been found to be extremely diverse between individuals, such that the percentage difference in group averages in schizophrenia studies (+16%) has been described as "not a very profound difference in the context of normal variation" (ranging from 25% to 350% of the mean average).<ref>{{cite journal |vauthors=Allen JS, Damasio H, Grabowski TJ  |title=Normal neuroanatomical variation in the human brain: an MRI-volumetric study |journal=American Journal of Physical Anthropology |volume=118 |issue=4 |pages=341–58 |date=August 2002 |pmid=12124914 |doi=10.1002/ajpa.10092 }}</ref>

The [[cave of septum pellucidum]] has been loosely associated with [[schizophrenia]],<ref>{{cite journal |vauthors=Galarza M, Merlo A, Ingratta A, Albanese E, Albanese A |title=Cavum septum pellucidum and its increased prevalence in schizophrenia: a neuroembryological classification |journal=The Journal of Neuropsychiatry and Clinical Neurosciences |volume=16 |issue=1 |pages=41–6 |year=2004 |pmid=14990758 |doi=10.1176/appi.neuropsych.16.1.41}}</ref> [[post-traumatic stress disorder]],<ref>{{cite journal |vauthors=May F, Chen Q, Gilbertson M, Shenton M, Pitman R |title=Cavum septum pellucidum in monozygotic twins discordant for combat exposure: relationship to posttraumatic stress disorder |journal=Biol. Psychiatry |volume=55 |issue=6 |pages=656–8 |year=2004 |pmid=15013837 |doi=10.1016/j.biopsych.2003.09.018 |pmc=2794416|url=https://dash.harvard.edu/bitstream/handle/1/28527471/nihms162099.pdf?sequence=1 }}</ref> [[traumatic brain injury]],<ref>{{cite journal |vauthors=Zhang L, Ravdin L, Relkin N, Zimmerman R, Jordan B, Lathan W, Uluğ A |title=Increased diffusion in the brain of professional boxers: a preclinical sign of traumatic brain injury? |journal=American Journal of Neuroradiology |volume=24 |issue=1 |pages=52–7 |year=2003 |pmid=12533327|pmc=8148951 }}</ref> as well as with [[antisocial personality disorder]].<ref name="Adrian Raine 2010 p.110"/>  CSP is one of the distinguishing features of individuals displaying symptoms of [[dementia pugilistica]].<ref>{{cite journal | last1 = McKee | first1 = AC | last2 = Cantu | first2 = RC | last3 = Nowinski | first3 = CJ | last4 = Hedley-Whyte | first4 = ET | last5 = Gavett | first5 = BE | last6 = Budson | first6 = AE | last7 = Santini | first7 = VE | last8 = Lee | first8 = HS | last9 = Kubilus | first9 = CA | last10 = Stern | first10 = RA | date = Jul 2009 | title = Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury | journal = Neuropathol Exp Neurol | volume = 68 | issue = 7| pages = 709–35 | doi = 10.1097/NEN.0b013e3181a9d503 | pmid=19535999 | pmc=2945234}}</ref>

== Additional media ==
<gallery>
File:Ventricular system.stl|3D model of ventricular system
File:Gray734.png|Scheme showing relations of the ventricles to the surface of the brain.
File:Lateral Ventricles - DK ATLAS.png|Lateral ventricles along with subcortical structures, in glass brain
</gallery>

== See also ==
{{Anatomy-terms}}
* [[Blood–brain barrier]]
* [[Circumventricular organs]]

== References ==
{{Reflist}}

{{Ventricular system}}
{{Authority control}}

[[Category:Ventricular system| ]]
[[Category:Brain anatomy]]