The lateral ventricle, together with the remaining cavities in the brain, is part of the general system in which cerebrospinal fluid circulates. They communicate with the subarachnoid space of the spinal cord. The inner surface of these cavities is lined with ependyma. Their function is to maintain an optimal pressure range inside and outside the brain and spinal cord.
Types of ventricles of the brain
The lateral ventricle (s) are small cavities in the large brain that produce specific cerebrospinal fluid. They are considered the largest of the ventricular system. This is a paired formation, and for it there is a specific topography.
The left lateral ventricle, according to tradition, is called the first. And the right one is the second. They are symmetrical between themselves and neighboring anatomical formations, and are located below the pineal gland on the sides of the midline. In each ventricle, the body and horns are distinguished: front, back and lower. The lateral ventricles through the holes of Monroe are connected to the third ventricle.
The third ventricle is located between the areas responsible for vision. It has the shape of a ring and in its wall is the gray matter of the brain, containing vegetative ganglia. In addition to the lateral ventricles, this cavity is connected to the aqueduct of the brain.
The fourth ventricle is located between the lower cerebellum. In shape, it resembles a pyramid and it is more correct to call it a rhomboid fossa. In addition to cerebrospinal fluid, at the bottom of this fossa is located most of the nuclei of the spinal nerves.
Vascular plexus
The lateral ventricle (s) are only partially involved in such a concept as the vascular plexus. The bulk of these structures is located in the roofs of the third and fourth ventricles. They are responsible for most of the production of cerebrospinal fluid. In addition to them, this function is performed directly by the nervous tissue, as well as ependyma, which covers the inside of the ventricle of the brain.
Morphologically, the vascular plexuses are outgrowths of the pia mater immersed in the ventricles. Outside, these protrusions are covered with a cubic specific choroid epithelium.
Ependymocytes
The lateral ventricles of the brain are lined with a special tissue inside, which can both produce cerebrospinal fluid and absorb it. This helps to maintain the optimal amount of fluid in the cavity and prevent an increase in intracranial pressure.
The cells of this epithelium have many organelles and a large nucleus. Their outer surface is covered with a large number of microvilli, they help promote cerebrospinal fluid, as well as its absorption. Outside of the ependyma, Colmer cells are located, which are considered a special type of macrophage that can move around the body.
Blood plasma flows through the multiple small gaps in the basement membrane of the epidermocytes into the ventricular cavity. Proteins produced directly by the cells of the internal epithelium of the brain cavities are added to it, and this produces cerebrospinal fluid.
Blood-brain barrier
The body and horns of the lateral ventricles with their inner lining form a blood-brain or blood-brain barrier. It is a collection of tissues arranged in a certain order:
- cytoplasm of the capillary endothelium;
- connective tissue containing macrophages;
- basement membrane of the endothelium;
- ependymal cells;
- the basement membrane of ependyma.
Such a complex design is necessary in order to prevent metabolic products, drugs and other toxic substances from entering the cerebrospinal fluid.
Cerebrospinal fluid
The norm of the lateral ventricles is the production of half a liter of cerebrospinal fluid per day, but only one hundred and forty milliliters of this amount is constantly circulating in the subarachnoid space. Despite the fact that the basis for cerebrospinal fluid is blood plasma, they have significant differences in the number of electrolytes and protein. The first is much higher, and the second is lower. In addition, a small amount of lymphocytes is normally present in the cerebrospinal fluid. Reverse absorption of cerebrospinal fluid occurs at the sites of introduction of the vascular plexus.
The following cerebrospinal fluid functions are distinguished:
- detoxification (transportation of metabolic products);
- depreciation (when walking, falling, making sharp turns);
- the formation of a hydrostatic membrane around the elements of the nervous system;
- maintaining the constancy of the composition of fluids in the central nervous system;
- transport (transfer of hormones and certain drugs).
Ventricular diseases
When one lateral ventricle (or both) produces more fluid than it can absorb, a pathological condition such as hydrocephalus develops. The internal volume of the ventricles of the brain gradually increases, squeezing the brain tissue. Sometimes this leads to irreversible ischemia and necrosis.
In newborns and young children, the symptoms of this disease are the disproportionate size of the brain skull compared with the facial skull, bulging fontanelles, causeless anxiety of the child, leading to apathy. Adults complain of headache, eye pain, nausea and vomiting.
For diagnosis, neuroimaging methods are used: magnetic resonance therapy or computed tomography. Timely detection and treatment of this disease avoids a significant number of complications and maintain the possibility of normal functioning.