Ventricular system of the brain: parts, characteristics and functions.

An overview of the parts, functions and anatomical features of the ventricular system.

The nervous system directs all the operations of our body. It is composed of various structures and other systems that interact with each other, allowing it to function properly.

Among these systems we find the ventricular system, which, although simple at first sight, fulfills a series of fundamental functions that directly influence the health of our brain.

Throughout this article we are going to deepen on what is the ventricular system, commenting how is its development in the brain.The development of the ventricular system during the formation of the nervous system, its functions and, also, some diseases that it can present.

What is the ventricular system?

In the brain there are hollows, cavities called ventricles, all of which are called the ventricular system.. It is a system that could be compared to a plumbing system, a system composed of several structures in the form of cavities that connect with each other.

Although the ventricles are empty and simple in appearance, these cavities actually fulfill fundamental functions for the nervous system, being the origin of the cerebrospinal fluid (CSF), a transparent liquid that bathes the brain and spinal cord.

Formation of the ventricular system

The ventricular system develops at the same time as the rest of the central nervous system.The ventricular system develops at the same time as the rest of the central nervous system, facilitating the circulation of CSF throughout the process. One of the first milestones in the development of this system occurs on day 26 of embryonic development (4th week), when the differentiation of the optic ventricle begins. Later, an evagination begins to occur in the medial line of the midbrain, which will later constitute the cerebral aqueduct or aqueduct of Sylvius.

Around the 6th week, the development of the interventricular foramen begins.The formation of the choroid plexus of the lateral ventricles begins. From that moment on, the grooves and segmentation become more noticeable to the naked eye. After a few more weeks, the medial and lateral ventricular eminence increase in size, which causes the spherical shape of the more primitive lateral ventricle to become a C. The horns of the lateral ventricles become more noticeable and a small sac forms in the diencephalic floor, which in the future will become the third ventricle.

In the course of the 7th and 8th weeks, the end of the process of formation of the ventricular system is reached.. It is at this time that the horns are finally defined, and the shape of the ventricles is almost definitively formed. The isthmic part is compressed by the cerebellum, which is still growing, and many villi extend into the midline.

Components of this system

The ventricular system is composed of four ventricles, which are connected to each other through various openings and canals. In the following we will see in depth which are its parts:

1. Lateral ventricles (I and II V).

The lateral ventricles are the first and second ventricles, being the most voluminous cavities of the ventricles.. They are located deep in both cerebral hemispheres and have an anterior horn oriented towards the frontal lobe and a posterior horn oriented towards the temporal lobe. These two ventricles are connected through the third ventricle by the interventricular orifice of Monro. Both are C-shaped and their volume increases as the years go by.

Inside each ventricle are the choroid plexuses. The walls and roof of both ventricles are formed by neural structures, which constitute the lobes of the ventricles.The walls and roof of both ventricles are formed by 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 in them the frontal horn (frontal lobe), the ventricular body (frontal and parietal lobes), occipital horn (occipital lobe) and the temporal horn (temporal lobe).

2. Third ventricle (III V)

The third ventricle is a thin, flat, bird's head-shaped cavity, similar in shape to a bird's head.. It is a single cavity, smaller than the lateral ventricles and centrally located. As mentioned above, it is connected to the lateral ventricles through the orifices of Monro and to the rest of the ventricular system through the aqueduct of Sylvius.

In its interior we also find the choroid plexus, specifically in its roof. The walls of this ventricle are formed by structures of the diencephalon, nuclei of the thalamus and hypothalamus. At its posterior end is the pineal gland, responsible for the production of melatonin, a hormone that regulates sleep and wake cycles.

3. Fourth ventricle (IV V)

The fourth ventricle is found occupying a space that runs from the mesencephalic aqueduct to the central canal of the upper part of the spinal cord..

Its floor, that is, the surface that forms the base of this cavity, is formed by the rhomboid fossa and communicates with the central canal through the foramina of Luschka and Magendie, parts from which CSF exits into the subarachnoid space. This cavity connects with the subarachnoid cisterns, which allow 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 subarachnoid space. the ventricles continue through the ependymal canal.. This canal is a cavity that originates at the end of the fourth ventricle and runs inside the medulla until it ends at the first vertebra of the lumbar region.

Functions of the cerebral ventricular system

Although it may seem a very simple system due to the simple fact that it is composed of cavities, the truth is that the cerebral ventricular system performs several very important tasks, which are the following.

1. CSF production

As we have mentioned before, the main function of the ventricles is to produce CSF, the main function of the cerebral ventricles is to produce cerebrospinal fluid (CSF).. It should also be noted that the ventricular system is not the only set of structures that form this fluid, such as the subarachnoid space, but it should be noted that the ventricles are very involved in the production of this fluid. This substance lubricates the neural structures.

About 80% of the CSF is synthesized in the choroid plexusesand is the product of the filtrate of Blood passing through them. The total volume of this fluid in an adult individual is about 150 ml. It is constantly produced and absorbed at a rate of 0.3 ml per minute, so that its total volume is completely renewed about 3 times each day.

2. Brain buoyancy

CSF causes the brain to be buoyant.. This may seem unimportant at first glance, but it causes the relative weight of the brain to decrease greatly, from about 1,400 grams to about 50 grams. This means that our head "does not weigh us" so much.

3. Brain preservation

By producing CSF, the ventricles help to maintain internal homeostasis. help maintain internal cerebral homeostasis, keeping intracranial pressure constant and adequate.. In addition to this, the ventricular system helps to eliminate waste, avoiding infections and fatal damage to our brain.

It is very important to understand that the brain is a very sensitive organ to any chemical and physical change within the skull, so that an altered ventricular system in which not enough CSF is produced (or too much is produced) can lead to cognitive damage, albeit 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 liquid protects us against external agents, which could pose an infectious risk to our brain..

In addition to this, the CSF is an effective shock absorber, so that in the event of an accident the brain trauma is softened, although it should be noted that it is not 100% effective and there is always a risk of cortical injury, especially if the impact has been very strong.

Diseases of the ventricular system

The ventricular system can suffer from several alterations and diseases, which not only affect the health of our brain but can also cause problems for the whole organism:

1. Hydrocephalus

Hydrocephalus is caused by an excessive production of CSF.. As this disorder increases, the intracranial pressure increases, which can lead to brain damage such as atrophy, metabolic and cognitive disorders. In the worst cases, hydrocephalus can lead to death.

2. Ventriculitis

Ventriculitis is the inflammation of the cerebral ventriclesThis causes the intracranial pressure to rise and also alters the circulation of CSF. This medical condition may be accompanied by hydrocephalus, encephalitis and inflammation of the brain.

3. Meningitis

Meningitis is inflammation of the meninges caused by an infectious agent.usually fungi, viruses and bacteria. This inflammation causes an increase in intracranial pressure, making CSF circulation difficult and resulting in different symptoms, mainly headaches, nausea, fever, sensitivity to light and in the worst cases cognitive impairment and even death.

4. Alzheimer's disease

In Alzheimer's disease there is acognitive deterioration caused by the death of neurons.This phenomenon increases as the disease progresses. This causes a reduction in neuronal density, which causes the ventricles to become larger and larger because they occupy the space left by the loss of brain volume.

5. Schizophrenia

In recent years, the possible relationship between schizophrenia and the alteration of the ventricular system has been increasingly investigated.. It is believed that people suffering from this psychiatric disorder may tend to present a greater dimension in the cerebral ventricles, having a greater ventricular dilatation and a significant cortical decrease.