The nervous system directs all the operations of our body. This is made up of several structures and other systems that interact with each other, allowing them to function properly.
Among these systems is the ventricular, which although at first glance simple performs a number of fundamental functions that directly influence the health of our brain.
Throughout this article we will deepen what the ventricular system is, commenting on its development throughout the formation of the nervous system, its functions and also certain diseases that may occur.
What is the ventricular system?
In the brain we find gaps, chambers called ventricles, which are all called ventricular systems.. It is a system that could well be compared to pipes, a system made up of several cavity-shaped structures that connect to each other.
Although the ventricles are hollow and simple in appearance, these chambers actually perform fundamental functions for the nervous system, being the source of cerebrospinal fluid (CSF), a clear fluid that bathes the brain and spinal cord.
Formation of the ventricular system
The ventricular system develops along with the rest of the central nervous system, facilitating the flow of CSF throughout the process. One of the first milestones in the development of this system occurs on the 26th day of embryonic development (4th week), when the differentiation of the optic ventricle begins. Later, evagination begins in the midline of the midbrain, which will later form the cerebral aqueduct or Silvio.
Around the 6th week, the development of the interventricular foramen begins, initiating the formation of the choroidal plexuses of the lateral ventricles. From this point on, the grooves and segmentation become a bit more visible to the naked eye. After a few more weeks, the medial and lateral ventricular eminence increases in size, causing the spherical shape of the more primitive lateral ventricle to become a C. The horns of the lateral ventricles begin to become more visible and form a small sac in the floor. diencephalic, which in the future will become the third ventricle.
In the 7th and 8th weeks, the end of the formation process of the ventricular system is reached. It is at this stage that the horns are definitively defined, the shape of the ventricles being formed almost definitively. The isthmic part is compressed by the cerebellum, which continues to grow, and many villi extend to the midline.
Components of this system
The ventricular system consists of four ventricles, which are connected to each other by various openings and channels. Below we will see in detail what are the parts:
1. Lateral ventricles (I and II V)
The lateral ventricles are the first and second ventricles, being the largest chambers. They are located deep in both cerebral hemispheres and have an anterior horn that faces the frontal lobe and a posterior horn that faces the temporal lobe. These two ventricles are connected by the third ventricle through the interventricular port of Monro. Both are C-shaped and their volume increases over the years.
Inside each we find the choroidal plexuses. The walls and ceiling of both ventricles are made up of neural structures, which constitute the frontal, parietal, temporal and occipital lobes, as well as the nuclei of the base and the corpus callosum. We can identify the frontal shaft (frontal lobe), the ventricular body (frontal and parietal lobes), the occipital shaft (occipital lobe) and the temporal shaft (temporal lobe).
2. Third ventricle (III V)
The third ventricle is a flat, thin cavity with a shape similar to that of a bird’s head. It is a single cavity, smaller than the lateral and central ventricles. As mentioned, it connects to the lateral ventricles through the Monro orifices and to the rest of the ventricular system through the Silvio aqueduct.
Inside, we also find the choroidal plexuses, especially on the ceiling. The walls of this ventricle are formed by structures of the diencephalon, nuclei of the thalamus and hypothalamus. At the posterior end is the pineal gland, responsible for the production of melatonin, a hormone that regulates the cycles of sleep and wakefulness.
3. Fourth ventricle (IV V)
The fourth ventricle occupies a space that runs from the mesencephalic aqueduct to the central canal of the upper part of the spinal cord.
Its floor, that is to say the surface which constitutes the base of this cavity, is formed by the rhomboidal fossa and communicates with the central channel through the holes of Luschka and Magendie, parts of which leave the CSF towards the subarachnoid space. This cavity connects to the subarachnoid cisterns, which allow the CSF to reach the subarachnoid space.
If we travel inside the ventricles and reach the spinal cord, we will observe that the ventricles continue through the ependymal duct. This duct is a cavity that originates at the end of the fourth ventricle and passes through the spinal cord to the first vertebra in the lumbar region.
Functions of the cerebral ventricular system
Although it may seem like a very simple system for the simple fact of being made up of cavities, the truth is that the cerebral ventricular system performs several very important tasks which are as follows.
1. Production of CRL
As we mentioned earlier, the main function of the brain ventricles is to produce cerebrospinal fluid. Likewise, the ventricular system is not the only set of structures that make up this fluid, such as the subarachnoid space, but it should be noted that the ventricles are heavily involved in the manufacture of this fluid. This substance lubricates neural structures.
About 80% of CSF is synthesized in the choroidal plexuses, and is the product resulting from the filtration of the blood which passes through them. The total volume of this liquid in an adult individual is approximately 150 ml. It is constantly produced and absorbed at the rate of 0.3 ml per minute, so its total volume is completely renewed about 3 times a day.
2. The buoyancy of the brain
CSF makes the brain float. This may not seem important at first, but it drastically decreases the relative weight of the brain, from about 1400 grams to about 50 grams. This means that our heads “don’t weigh” that much.
3. Preservation of the brain
Thanks to the fact that they produce CSF, the ventricles they help to maintain the internal homeostasis of the brain, keeping the intracranial pressure constant and adequate. In addition, the ventricular system helps eliminate waste, prevent infections and fatal damage to our brain.
It is very important to understand that the brain is an organ very sensitive to any chemical and physical changes within the skull, so an impaired ventricular system in which there is not enough (or too much) CSF can cause cognitive damage. , although indirectly.
4. Immunoprotection and physical protection
As the last major function of the ventricular system, directly associated with its production of CSF, we have the fact that this fluid protects us from external agents, which could present an infectious risk to our brain.
In addition, the CSF is an effective shock absorber, softening the trauma of the brain in the event of an accident, although it should be noted that it is not 100% effective and there is always a risk of damage to the cortex. especially if the impact was very strong.
Diseases of the ventricular system
The ventricular system can suffer from various alterations and diseases, which not only condition the health of our brain but can also lead to problems for the whole body:
Hydrocephalus is caused by excessive production of CSF. As this disorder also increases, intracranial pressure increases, which can lead to brain damage such as atrophy, metabolic and cognitive disorders. In the worst case, hydrocephalus can lead to the death of the individual.
Ventriculitis is inflammation of the brain ventricles, which causes an increase in intracranial pressure and also impairs the flow of CSF. This medical condition can be accompanied by hydrocephalus, encephalitis, and inflammation of the brain.
Meningitis is inflammation of the meninges due to an infectious agent, usually fungi, viruses and bacteria. This inflammation causes an increase in intracranial pressure, making it difficult for CSF to flow and leading to various symptoms, mainly headache, nausea, fever, sensitivity to light and at worst cognitive impairment and even death.
4. Alzheimer’s disease
In Alzheimer’s disease occurs orn cognitive impairment caused by the death of neurons, a phenomenon that increases as the disease progresses. This causes a reduction in neuronal density, which causes the ventricles to grow larger and larger as they take up the space left by the loss of brain volume.
In recent years, the possible relationship between schizophrenia and alteration of the ventricular system has been increasingly investigated.. It is believed that people with this psychiatric disorder may tend to have a larger dimension in the cerebral ventricles, having greater ventricular dilation and significant cortical decrease.
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