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In neuroanatomy, the ventricular system is a set of four interconnected cavities known as cerebral ventricles in the brain. (2025). 9780323073073, Elsevier. ISBN 9780323073073 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, (2025). 9780323073073, Elsevier. ISBN 9780323073073 allowing for the flow of CSF to circulate. (2025). 9780123704917, Elsevier. ISBN 9780123704917
All of the ventricular system and the central canal of the spinal cord are lined with ependyma, a specialised form of epithelium connected by that make up the blood–cerebrospinal fluid barrier.
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.
| third ventricle |
| fourth ventricle |
| subarachnoid space via the cisterna magna |
| subarachnoid space via the cistern of great cerebral vein |
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.
In more detail, around the third week of development, the embryo is a three-layered disc. The embryo is covered on the 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.
As the brain develops, by the fourth week of embryological development three swellings known as 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: The neural stem cells of the developing brain, principally radial glial cells, line the developing ventricular system in a transient zone called the ventricular zone.
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. 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 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.
The fluid then flows around the superior sagittal sinus to be reabsorbed via the arachnoid granulations (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 lumbar cistern at the end of the cord around the cauda equina where are performed.
The cerebral aqueduct between the third ventricle and is very small, as are the foramina, which means that they can be easily blocked.
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.Klein, S.B., & Thorne, B.M. Biological Psychology. Worth Publishers: New York. 2007.Saladin, Kenneth S. Anatomy & Physiology. The Unit of Form and Function. 5th Edition. McGraw-Hill: New York. 2007
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 study of CT scans of the ventricles in the late 1970s gave new insight into the study of . 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 in origin and led to a renewed interest in its study via the use of 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. 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).
The cave of septum pellucidum has been loosely associated with schizophrenia, post-traumatic stress disorder, traumatic brain injury, as well as with antisocial personality disorder. CSP is one of the distinguishing features of individuals displaying symptoms of dementia pugilistica.
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