In order to work normally and maintain the vital activity of the body, the brain must be protected from external negative factors that can damage it. In the role of protection are not only the bones of the skull, but also the shells of the brain, which are the so-called protective case with numerous layers and structure. The layers of the meninges form the cistern of the brain , which contribute to the normal activity of the plexuses of the vessels, as well as the circulation of the cerebrospinal fluid. What are the tanks, what role they perform, we will consider below.
Brain shells
The membranes have several layers: the solid, which is located near the bones of the skull, arachnoid or arachnoid, as well as the choroid, called the soft leaf, which covers the brain tissue and fuses with it. Let us consider in more detail each of them:
- The hard shell has a close relationship with the bones of the skull. On its inner surface there are processes that enter the brain cracks in order to separate the departments. The largest process is located between the two hemispheres and forms a sickle, the back of which connects to the cerebellum, limiting it from the occipital parts. At the top of the hard shell there is another process that forms the diaphragm. All this contributes to providing good protection against pressure of the brain mass on the pituitary gland. In some parts of the brain are the so-called sinuses, through which venous blood flows.
- Arachnoid shell is placed inside the solid, which is quite thin, transparent, but strong and strong. It breaks the substance of the brain. Under this membrane there is a subarachnoid space that separates it from the soft sheet. It contains cerebrospinal fluid. Above deep grooves, the subarachnoid space is wide enough, as a result of which cisterns of the brain are formed .
The meninges are structures of connective tissue that cover the spinal cord. Without tanks, the brain and nervous system will not function.
Varieties of tanks and their location
The main volume of cerebrospinal fluid (cerebrospinal fluid) is located in the tanks, which are located in the region of the stem part of the brain. Under the cerebellum in the posterior cranial fossa is the main cistern of the brain, called the large occipital or cerebellar-cerebral. Next is the preontina or cistern of the bridge. It is located in front of the bridge, bordering the intersternal cistern, behind it borders the cerebellar-cerebral cistern and subarachnoid space of the spinal cord. Next are the basal cisterns of the brain . They are pentagonal in shape and contain tanks such as the inter-foot and crossroads. The first is located between the legs of the brain, and the second is between the frontal lobes and the intersection of the optic nerves. The bypass or bypass tank has the shape of a distorted channel that is located on both sides of the legs of the brain, borders on the front with such tanks as the interstitial and pavement, and on the back - with the quadruple. Next, consider the quadruple- chambered or retrocerebellar cistern of the brain where it is located . It is placed between the cerebellum and the corpus callosum. In her area, the presence of arachnoid (retrocerebellar) cysts is often noted. If the cyst increases in size, then a person may experience increased pressure inside the skull, impaired hearing and vision, balance and orientation in space. The cistern of the lateral fossa is located in the large brain, in its lateral groove.
The brain cisterns are located predominantly in the front of the brain. They communicate through the holes of Lushka and Magendie and are filled with cerebrospinal fluid (cerebrospinal fluid).
Cerebrospinal fluid movement
The cerebrospinal fluid cycle occurs continuously. That is how it should be. It fills not only the subarachidic space, but also the central brain cavities that are located deep in the tissue and are called the cerebral ventricles (there are four in total). In this case, the fourth ventricle is associated with the cerebrospinal canal of the spine. The liquor itself performs several roles:
- surrounds the outer layer of cortical substance;
- moves in the ventricles;
- penetrates the brain tissue along the vessels;
So, the brain cisterns are part of the cerebrospinal fluid circulation line, are its external storage, and the ventricles are the internal reservoir.
CSF formation
The synthesis of cerebrospinal fluid begins in the connections of the vessels of the cerebral ventricles. They are outgrowths with a velvety surface that are located on the walls of the ventricles. Tanks and their cavities are interconnected. Big tank of the brain interacts with the fourth ventricle with the help of special cracks. The synthesized cerebrospinal fluid enters through the openings into the subarachnoid space.
Features
The cerebrospinal fluid circulation has different directions of movement, it occurs slowly, depending on the pulsation of the brain, respiratory rate, and development of the spine as a whole. The main part of the cerebrospinal fluid is absorbed by the venous system, the rest - by the lymphatic system. Liquor is closely associated with the meninges and tissue, provides the normalization of metabolic processes between them. Liquor provides an additional outer layer that protects the brain from injuries and disorders, and also compensates for the distortion of its size, making movements, depending on the dynamics, supports the energy of neurons and the balance of osmosis in tissues. Through the cerebrospinal fluid, toxins are emitted into the venous system, which appear in the cerebral tissue during metabolism. Liquor serves as a barrier at the turn of the bloodstream, it delays some substances that come from the blood, and passes others. In a healthy person, this barrier helps prevent various toxins from entering the brain tissue from the blood.
Features in children
The subarachnoid membrane in children is very thin. In a newborn baby, the volume of subarachnoid space is very large. As it grows, space increases. It reaches such a volume as in an adult, already by adolescence.
Tank deformation
Tanks play a special role in the movement of cerebrospinal fluid. The expansion of the brain cistern signals a disorder in the activity of the cerebrospinal fluid system. The increase in the size of the large cistern, which is located in the posterior cranial fossa of a small size, leads to deformation of the brain structure quite quickly. Usually people do not feel discomfort with a slight increase in tanks. He may be disturbed by minor headaches, mild nausea, and visual impairment. If the disease continues to develop, it can lead to serious health hazards. Therefore, the synthesis and absorption of cerebrospinal fluid must maintain equilibrium.
If the brain’s cistern is enlarged and a large amount of cerebrospinal fluid is collected in it, they speak of a disease such as hydrocephalus. Consider this issue in more detail.
Hydrocephalus
This disease is formed when the cerebrospinal fluid circulation is disturbed. The reason for this may be increased synthesis of cerebrospinal fluid, difficulties in its movement between the ventricles and the subarachnoid space, a failure of the absorption of cerebrospinal fluid through the walls of the veins. Hydrocephalus is internal (fluid forms in the ventricles), and external (fluid accumulates in the subarachnoid space). The disease occurs with inflammation or metabolic disorders, congenital malformations of the pathways that conduct cerebrospinal fluid, as well as brain injuries. The presence of cysts also leads to the appearance of symptoms of pathology. A person complains of headaches in the morning, nausea, vomiting. Stagnation at the bottom of the eye or swelling of the optic nerve may be observed. In this case, a brain tomography is performed to make the correct diagnosis.
Fetal brain cistern
From the eighteenth to the twentieth week of pregnancy, women according to the results of ultrasound, we can talk about the state of the cerebrospinal fluid system. The data make it possible to judge the presence or absence of brain pathology. A large tank is easily identified using an axial scan plane. It gradually increases in parallel with the growth of the fetus. So, at the beginning of the sixteenth week the tank is about 2.8 mm, and at the twenty-sixth week its size increases to 6.4 mm. If the tanks are larger, they talk about pathological processes.
Pathology
The causes of pathological changes in the brain can be congenital or acquired. The first include:
- Arnold-Chiari AVM, which occurs when the outflow of cerebrospinal fluid is impaired;
- AVM Dandy Walker;
- The narrowing of the water supply to the brain, as a result of this there is an obstacle to the movement of CSF;
- chromosome disorders at the genetic level;
- craniocerebral hernia;
- agenesis of the corpus callosum;
- cysts leading to hydrocephalus.
Acquired causes include:
- intrauterine hypoxia;
- injury to the brain or spinal cord;
- cysts or neoplasms that violate the flow of cerebrospinal fluid;
- infections affecting the central nervous system;
- thrombosis of vessels into which cerebrospinal fluid enters.
Diagnostics
In case of violations in the cerebrospinal fluid system, the following diagnostics are carried out: MRI, CT, fundus examination, study of brain tanks using radionuclide cisternography, as well as neurosonography.
It is very important to know how the cerebrospinal fluid system works, how its pathology arises and manifests itself. In order to undergo full treatment in case of detection of pathologies, it is necessary to consult a specialist in time. In addition, the results of ultrasound at different stages of pregnancy make it possible to study the development of the fetal brain in order to make a correct prognosis and plan treatment in the future.