Grooves and convolutions of the brain: spur, Sylvieva, Rolandova and others

The convolutions and grooves (gyri and sulci) of the brain are deeply and firmly connected structural formations under the vault of the skull.

The wrinkled surface, which can be habitually seen in the images of the GM, is formed by their combination and alternation.

Protrusions and depressions, whimsically scattered by nature over the vast space of the telencephalon (endbrain) - a perfect and developed structure covering other departments of the GM.

Anatomical structure of the lobes of the brain

In the structure of any organ of the human body that has undergone development in evolutionary dynamics, one can trace the expediency of nature, which provided for and transformed some organs.

The grooves and convolutions of the hemispheres are found in the structure of the human GM and in the brain structures of some mammals. Their formation was dictated by the need to fit a large surface under the virtually unchanged cranial vault.

The transition of a person to upright posture and his development led to the need to form a larger volume of brain structures.

But an increase in the bony protective vault would lead to disproportion, weighting, because of which the head could not be at the top of the body.

And there was an objective need for this, since it is in it that the main catchers and analyzers of information coming from outside are located.

Thanks only to the incoming significant volume of information flow, a person could not achieve his current, dominant and exclusive position - the surrounding reality demanded the formation of sensations, practical experience, the ability to analyze and compare the already accumulated knowledge and correlate it with a new one for oneself, or similar situation.

Speech appeared due to the accumulation of gnosis and praxis, and its formation led to abstract thinking - this ability, the performance of complex movements and their chains, the higher mental functions, all this is the result of transformations that nature has done, increasing surface areas by forming folds and depressions and accommodating a large volume in a limited space.

65-70% of the bark is located in the newly formed furrows, if not for the packaging carried out by nature in this way, a person would have only a third of the existing volume at his disposal, which is located on the surface of both hemispheres.

Studies have shown that the pattern of gyri and sulcus is individual in different people. All people and some animals have deep and large folds. The answer to the question - how many convolutions a person has in the brain - will not be accurate, the number is variable, the formation of new ones or the absence customary so diverse that there are special atlases in which examples of the individual structure of the final brain.

Unity of opposites

The main differences between the groove and gyrus are not so much in the functions performed, but in the location of these formations relative to each other. But they are inextricably linked, because they are formed at the stage of gyrification during intrauterine development from the frontal (or primary anterior) cerebral bladder.

The brains are elevations above the surface of the GM, while the grooves are localized in the inter-brains space and delimit these protrusions. An undeniable connecting role white matter with its specific constituent component - a beam axons (conductors of nerve impulses), covered with a special myelin.

Telencephalon is a formation of several important structures:

• two cerebral hemispheres;
• densely and reliably covering their bark (thin layer gray medullareaching a maximum of several mm);
• specific plexus neurons — corpus callosum, inherent exclusively to mammals;
• fancifully assembled from gray and white stripes of the corresponding brain substances striatum, part of the system basal nuclei hemispheres of the GM;
• olfactory brain with its complex structure, division into the periphery and the center.

The differentiation of GM furrows by type, embryogenesis, and functionality implies differentiation into primary, secondary, and tertiary. The latter are not taken into account when studying the anatomical structure, since they are deeply individual for each person. They are small enough and have no names.

Toponyms and eponyms are found only in primary and secondary grooves, but the primary ones differ not only location (they are present both inside the lobes, and as an interlobar unifying-delimiting deepening).

Types and location

Primary depressions are the main and delineating grooves located between the two hemispheres or major regions of the brain.

Their formation occurs as early as 10 weeks of gestation, it is laid down in the program according to which the brain bubbles work:

1. Sylvian sulcus, separating the temporal from the frontal and parietal, is now more often called lateral furrow, together with the central and parieto-occipital, they delimit the upper-lateral surface.
2. In front of the central one is the frontal lobe, behind it is the parietal, it separates them among themselves, like the central one. Initially received an eponymous name, you can find the term "Rolandova".
3. The cingulate line serves as a boundary for all major segments localized in the olfactory brain.
4. The parietal occipital delimits those lobes from the names of which its own (parietal and occipital) is formed.

The medial surface is simply dotted with deep permanent grooves - here are hippocampal, cingulate, collateral, geographically close to the occipital lobe, and not far from it - spur. But the first one that anatomists remember when they mention the medial surface is the groove corpus callosum, because between it and the cingulate, forming the forking, is the encircling gyrus. Although the hippocampal and collateral are also a kind of border for the gyrus of the temporal cortex.

A little about convolutions

In the lower surface of the cortex are the olfactory, orbital, straight and inferior temporal grooves. They are part of different departments, because the lower surface belongs to the temporal, frontal and occipital lobes.

In this brain segment there is only one gyrus that deserves attention - the lingual (in another transcription - lingual, gyrus lingualis), which is separated by the spur and collateral grooves.

The presence of grooves is invariably associated with the presence of convolutions formed by the transformation of brain tissue to save space:

1. The frontal lobe has as many as 6 convolutions, of which four are on the outer surface, and two are on the inner. This amount is easily explained by the value of LD, which occupies more than a quarter of the entire human brain. The straight and orbital gyri are internal formations, and the vertical precentral, superior, inferior and middle gyrus are external. The precentral (in other sources - precentral) is formed by the groove of the same name and the central one, the place of dislocation middle - naturally, between the upper and lower frontal sulcus, the lower one is located between the corresponding frontal and Sylvieva. The posterior third of the middle frontal gyrus contains the center of the letter, and the motor center is located in the inferior frontal gyrus.
2. The boundaries of the parietal region are Rolandova (from the frontal), Silvieva (from the temporal), and the parieto-occipital. It contains the postcentral, bounded by the groove of the same name and the central, angular, near the upper temporal sulcus, two horizontally located lobules (inferior and superior parietal), and supra-marginal, next to Sylvieva furrow.
3. There are only two gyri on the basal surface of the temporal lobe, but very important: the hippocampus and the lateral occipitotemporal. The dislocation in the inner space of the occipital lobe of 2 formations: the gyrus lingualis and the parietal-occipital gyrus, is due to the presence of a furrow, which separates them from each other.

Brain sinuses and cerebral grooves are difficult to see in isolation. Their deep and lasting ties are due to age-old changes and transformations. Nature worked, creating the basic architectonics of the most important structural formation, adjusting its constituent elements as closely as possible to the existing needs.

You can consider them not as separate parts, but as part of a single whole, a kind of keys that the central nervous system presses, if a person changes the type of activity, performs some actions, begins, ends or continues what he has learned in the process of a long improvement.

Functions of the grooves and convolutions of the brain

In many ways, the functionality inherent in brain formations determines their location. The conditional division assumes the presence of lobes located in the frontal, parietal, occipital or temporal lobes, amenable to visualization and insular, covered by the rest and therefore discovered later.

Tertiary formations are the result of individual development, therefore, such a variety of options for their location are presented in the anatomical atlas. But without primary furrows, it is impossible to imagine a reasonable person who became the result a long and complex process of optimization, transformation, development - all that is called the process of evolution.

Anterior central gyrus, part pyramidal system, when damaged, causes a complete absence of conscious movements. The hippocampus is responsible for memory, and the angular gyrus is responsible for recognizing visual images obtained with the help of the visual organs.

The names already given to them speak about the appointment of the lingual and olfactory, but the common person hears little about the functions of the postcentral and marginal gyri. Meanwhile, the postcentral one serves as a center for pain and temperature sensitivity, is responsible for touch, although the upper parietal lobe is responsible for the stereognosis function.

The supra-marginal one serves as the focus of praxia - all that is necessary for a person in his work - it fixes the skills acquired in work and sports.

Slightly below the supra-marginal is the corner one, without which a person could not read. Longitudinal, located in the temporal lobe, contain the sensory center of speech, the nucleus of the auditory analyzer and, despite its existence immediately after birth, they improve and become more complicated throughout life.