Add to favorites

Development of the nervous system after birth. Formation of the child’s nervous system

Samara branch of Moscow State Pedagogical University

Abstract on the topic:

Critical periods in the development of the central nervous system in a child

Completed by: 3rd year student

Faculty of Psychology and Education

Kazakova Elena Sergeevna

Checked:

Korovina Olga Evgenievna

Samara 2013

Development of the nervous system.

The nervous system of higher animals and humans is the result of long-term development in the process of adaptive evolution of living beings. The development of the central nervous system occurred primarily in connection with the improvement of the perception and analysis of influences from the external environment.

At the same time, the ability to respond to these influences with a coordinated, biologically appropriate reaction also improved. The development of the nervous system also occurred due to the increasing complexity of the structure of organisms and the need to coordinate and regulate the work of internal organs. To understand the activity of the human nervous system, it is necessary to become familiar with the main stages of its development in phylogenesis.

The emergence of the central nervous system.

The lowest organized animals, for example the amoeba, do not yet have any special receptors, no special motor apparatus, or anything resembling a nervous system. An amoeba can perceive irritation in any part of its body and react to it with a peculiar movement by forming an outgrowth of protoplasm, or pseudopodia. By releasing the pseudopodia, the amoeba moves towards an irritant, such as food.

In multicellular organisms, during the process of adaptive evolution, specialization of various parts of the body arises. Cells appear, and then organs, adapted for the perception of stimuli, for movement and for the function of communication and coordination.

The appearance of nerve cells not only made it possible to transmit signals over a greater distance, but also provided the morphological basis for the rudiments of coordination of elementary reactions, which leads to the formation of an integral motor act.

Subsequently, as the animal world evolves, the apparatus of reception, movement and coordination develops and improves. Various sense organs appear, adapted to perceive mechanical, chemical, temperature, light and other stimuli. A complex motor apparatus appears, adapted, depending on the animal’s lifestyle, for swimming, crawling, walking, jumping, flying, etc. As a result of the concentration, or centralization, of scattered nerve cells into compact organs, the central nervous system and peripheral nerves arise ways. Along some of these paths, nerve impulses are transmitted from receptors to the central nervous system, through others - from centers to effectors.

General diagram of the structure of the human body.

The human body is a complex system of numerous and closely interconnected elements, combined into several structural levels. The concept of growth and development of an organism is one of the fundamental concepts in biology. The term “growth” currently refers to an increase in the length, volume and body weight of children and adolescents associated with an increase in the number of cells and their number. Development is understood as qualitative changes in the child’s body, consisting in the complication of its organization, i.e. in the complication of the structure and function of all tissues and organs, the complication of their relationships and the processes of their regulation. Child growth and development, i.e. quantitative and qualitative changes are closely interrelated with each other. Gradual quantitative and qualitative changes that occur during the growth of the body lead to the appearance of new qualitative characteristics in the child.

The entire period of development of a living being, from the moment of fertilization to the natural end of individual life, is called ontogenesis (Greek ONTOS - existing, and GINESIS - origin). In ontogenesis, two relative stages of development are distinguished:

1. Prenatal - begins from the moment of conception until the birth of the child.

2. Postnatal - from the moment of birth to death of a person.

Along with the harmonious development, there are special stages of the most dramatic spasmodic atom-physiological transformations.

In postnatal development there are three such " critical period" or "age crisis":

	Changing Factors	Consequences
from 2x to 4x	Development of the sphere of communication with the outside world. Development of speech form. Development of a form of consciousness.	Increasing educational requirements. Increased motor activity
from 6 to 8 years	New people. New friends. New responsibilities	Decreased motor activity
from 11 to 15 years	Changes in hormonal balance with maturation and restructuring of the endocrine glands. Expanding your social circle	Conflicts in the family and at school. Hot temper

An important biological feature in the development of a child is that the formation of their functional systems occurs much earlier than they need it.

The principle of accelerated development of organs and functional systems in children and adolescents is a kind of “insurance” that nature gives to humans in case of unforeseen circumstances.

A functional system is a temporary combination of various organs of a child’s body, aimed at achieving a result useful for the existence of the organism.

Purpose of the nervous system.

The nervous system is the leading physiological system of the body. Without it, it would be impossible to connect countless cells, tissues, and organs into a single hormonal working whole.

The functional nervous system is divided “conditionally” into two types:

Thus, thanks to the activity of the nervous system, we are connected with the world around us, we are able to admire its perfection, and learn the secrets of its material phenomena. Finally, thanks to the activity of the nervous system, a person is able to actively influence the surrounding nature and transform it in the desired direction.

At the highest stage of its development, the central nervous system acquires another function: it becomes an organ of mental activity, in which, on the basis of physiological processes, sensations, perceptions arise and thinking appears. The human brain is an organ that provides the possibility of social life, communication between people, knowledge of the laws of nature and society and their use in social practice.

Let's give some idea about conditioned and unconditioned reflexes.

Features of unconditioned and conditioned reflexes.

The main form of activity of the nervous system is reflex. All reflexes are usually divided into unconditioned and conditioned.

Unconditioned reflexes- these are innate, genetically programmed reactions of the body, characteristic of all animals and humans. The reflex arcs of these reflexes are formed during the process of prenatal development, and in some cases, during the process of postnatal development. For example, innate sexual reflexes are finally formed in a person only at the time of puberty in adolescence. Unconditioned reflexes have conservative, little changing reflex arcs passing mainly through the subcortical sections of the central nervous system. The participation of the cortex in the course of many unconditioned reflexes is optional.

Conditioned reflexes- individual, acquired reactions of higher animals and humans, developed as a result of learning (experience). Conditioned reflexes are always individually unique. Reflex arcs of conditioned reflexes are formed in the process of postnatal ontogenesis. They are characterized by high mobility and the ability to change under the influence of environmental factors. Reflex arcs of conditioned reflexes pass through the higher part of the brain - the CGM.

Classification of unconditioned reflexes.

The question of the classification of unconditioned reflexes still remains open, although the main types of these reactions are well known. Let us dwell on some particularly important unconditioned human reflexes.

1. Food reflexes. For example, salivation when food enters the oral cavity or the sucking reflex in a newborn baby.

2. Defensive reflexes. Reflexes that protect the body from various adverse effects, an example of which may be the reflex of withdrawing the hand when a finger is painfully irritated.

3. Orienting reflexes. Any new unexpected stimulus attracts the person’s attention.

4. Gaming reflexes. This type of unconditioned reflexes is widely found in various representatives of the animal kingdom and also has adaptive significance. Example: puppies playing. They hunt each other, sneak up and attack their “enemy”. Consequently, during the game the animal creates models of possible life situations and carries out a kind of “preparation” for various life surprises.

While maintaining its biological foundations, children's play acquires new qualitative features - it becomes an active tool for learning about the world and, like any other human activity, acquires a social character. Play is the very first preparation for future work and creative activity.

The child's play activity appears from 3-5 months of postnatal development and underlies the development of his ideas about the structure of the body and the subsequent isolation of himself from the surrounding reality. At 7-8 months play activity acquires an “imitative or educational” character and contributes to the development of speech, improvement of the child’s emotional sphere and enrichment of his ideas about the surrounding reality. From the age of one and a half years, the child’s play becomes more and more complicated; the mother and other people close to the child are introduced into play situations, and thus the foundations are created for the formation of interpersonal, social relationships.

In conclusion, it should also be noted that sexual and parental unconditioned reflexes associated with the birth and feeding of offspring, reflexes that ensure movement and balance of the body in space, and reflexes that maintain homeostasis of the body.

Instincts. A more complex, unconditional reflex activity is instincts, the biological nature of which remains unclear in its details. In a simplified form, instincts can be represented as a complex interconnected series of simple innate reflexes.

Physiological mechanisms of formation of conditioned reflexes.

For the formation of a conditioned reflex, the following essential conditions are necessary:

1) Presence of a conditioned stimulus

2) Availability of unconditional reinforcement

The conditioned stimulus must always somewhat precede the unconditional reinforcement, that is, serve as a biologically significant signal; the conditioned stimulus, in terms of the strength of its effect, must be weaker than the unconditioned stimulus; finally, for the formation of a conditioned reflex, a normal (active) functional state of the nervous system is necessary, especially its leading part - the brain. Any change can be a conditioned stimulus! Powerful factors contributing to the formation of conditioned reflex activity are reward and punishment. At the same time, we understand the words “reward” and “punishment” in a broader sense than just “satisfying hunger” or “painful influence”. It is in this sense that these factors are widely used in the process of teaching and raising a child, and every teacher and parent is well aware of their effective action. True, up to 3 years of age, “food reinforcement” is also of key importance for the development of useful reflexes in a child. However, then “verbal encouragement” acquires leading importance as reinforcement in the development of useful conditioned reflexes. Experiments show that in children over 5 years old, with the help of praise, you can develop any useful reflex in 100% of cases.

Thus, educational work, in its essence, is always associated with the development in children and adolescents of various conditioned reflex reactions or their complex interconnected systems.

Classification of conditioned reflexes.

Classification of conditioned reflexes due to their large number is difficult. There are exteroceptive conditioned reflexes formed when exteroceptors are stimulated; interoceptive reflexes formed by irritation of receptors located in internal organs; and proprioceptive, arising from stimulation of muscle receptors.

There are natural and artificial conditioned reflexes. The former are formed by the action of natural unconditioned stimuli on the receptors, the latter by the action of indifferent stimuli. For example, the secretion of saliva in a child when he sees his favorite candy is a natural conditioned reflex, and the secretion of saliva that occurs in a hungry child when he sees dinnerware is an artificial reflex.

The interaction of positive and negative conditioned reflexes has important for adequate interaction of the body with the external environment. Such an important feature of a child’s behavior as discipline is associated precisely with the interaction of these reflexes. In physical education lessons, in order to suppress self-preservation reactions and feelings of fear, for example, when performing gymnastic exercises on the uneven bars, students’ defensive negative conditioned reflexes are inhibited and positive motor ones are activated.

A special place is occupied by conditioned reflexes for time, the formation of which is associated with stimuli regularly repeated at the same time, for example, with food intake. That is why, by the time of eating, the functional activity of the digestive organs increases, which has a biological meaning. Such rhythmicity of physiological processes underlies the rational organization of the daily routine of preschool and school-age children and is a necessary factor in the highly productive activity of an adult. Reflexes for time, obviously, should be classified as a group of so-called trace conditioned reflexes. These reflexes are developed if unconditional reinforcement is given 10-20 s after the final action of the conditioned stimulus. In some cases, it is possible to develop trace reflexes even after a 1-2 minute pause.

Imitation reflexes, which are also a type of conditioned reflexes, are important in a child’s life. To develop them, it is not necessary to take part in the experiment; it is enough to be its “spectator”.

Higher nervous activity in the early and preschool periods of development (from birth to 7 years).

A child is born with a set of unconditioned reflexes. reflex arcs of which begin to form in the 3rd month of prenatal development. Thus, the first sucking and breathing movements appear in the fetus precisely at this stage of ontogenesis, and active movement of the fetus is observed in the 4-5th month of intrauterine development. By the time of birth, the child has formed the majority of congenital unconditioned reflexes, providing him with the normal functioning of the vegetative sphere, his vegetative “comfort”.

The possibility of simple food conditioned reactions, despite the morphological and functional immaturity of the brain, arises already on the first or second day, and by the end of the first month of development, conditioned reflexes from the motor analyzer and vestibular apparatus are formed: motor and temporary. All these reflexes form very slowly, they are extremely gentle and easily inhibited, which is apparently due to the immaturity of the cortical cells and the sharp predominance of excitation processes over inhibitory ones and their wide irradiation.

From the second month of life, auditory, visual and tactile reflexes are formed, and by the 5th month of development, the child develops all the main types of conditioned inhibition. Education of the child is important in improving conditioned reflex activity. The earlier training begins, that is, the development of conditioned reflexes, the faster their formation subsequently occurs.

By the end of the first year of development, the child is relatively good at distinguishing the taste of food, smells, shape and color of objects, and distinguishes voices and faces. Movements improve significantly, and some children begin to walk. The child tries to pronounce individual words ("mom", "dad", "grandfather", "aunt", "uncle", etc.), and he develops conditioned reflexes to verbal stimuli. Consequently, already at the end of the first year, the development of the second signaling system is in full swing and its joint activity with the first is being formed.

Speech development is a difficult task. It requires coordination of the respiratory muscles, muscles of the larynx, tongue, pharynx and lips. Until this coordination has developed, the child pronounces many sounds and words incorrectly.

Speech formation can be facilitated by correct pronunciation of words and grammatical phrases so that the child constantly hears the patterns he needs. Adults, as a rule, when addressing a child, try to copy the sounds that the child makes, believing that in this way they will be able to connect with him " mutual language". This is a deep misconception. There is a huge distance between a child’s understanding of words and the ability to pronounce them. The lack of the necessary role models delays the development of a child’s speech.

The child begins to understand words very early, and therefore, for the development of speech, it is important to “talk” with the child from the first days after his birth. When changing a vest or diaper, shifting a child or preparing him for feeding, it is advisable to do this not silently, but to address the child with the appropriate words, naming your actions.

The first signaling system is the analysis and synthesis of direct, specific signals of objects and phenomena of the surrounding world, coming from visual, auditory and other receptors of the body and components

The second signaling system is (only in humans) the connection between verbal signals and speech, the perception of words - audible, spoken (aloud or silently) and visible (when reading).

In the second year of child development, all types of conditioned reflex activity are improved and the formation of the second signaling system continues, the vocabulary increases significantly (250-300 words); immediate stimuli or their complexes begin to evoke verbal reactions. If in a one-year-old child conditioned reflexes to direct stimuli are formed 8-12 times faster than to a word, then at two years old words acquire signal meaning.

Of decisive importance in the formation of the child’s speech and the entire second signaling system as a whole is the child’s communication with adults, i.e. surrounding social environment and learning processes. This fact is yet another proof of the decisive role of the environment in the development of the potential capabilities of the genotype. Children deprived of a linguistic environment and communication with people do not speak; moreover, their intellectual abilities remain at a primitive animal level. Moreover, the age from two to five is “critical” in mastering speech. There are cases where children abducted by wolves in early childhood and returned to human society after five years are able to learn to speak only to a limited extent, and those returned only after 10 years are no longer able to utter a single word.

The second and third years of life are distinguished by lively orientation and research activities. “At the same time,” writes M. M. Koltsova, “the essence of the orienting reflex of a child of this age can be more correctly characterized not by the question “what is this?”, but by the question “what can be done with it?” The child reaches out to every object, touches touches him, pushes him, tries to lift him, etc.”

Thus, the described age of the child is characterized by the “objective” nature of thinking, i.e. decisive muscle sensations. This feature is largely associated with the morphological maturation of the brain, since many motor cortical zones and zones of musculocutaneous sensitivity already reach a fairly high functional usefulness by the age of 1-2 years. The main factor stimulating the maturation of these cortical zones is muscle contractions and high motor activity of the child. Limiting his mobility at this stage of ontogenesis significantly slows down mental and physical development.

The period up to three years is also characterized by the extraordinary ease of formation of conditioned reflexes to a wide variety of stimuli, including the size, heaviness, distance and color of objects. Pavlov considered these types of conditioned reflexes to be prototypes of concepts developed without words (“grouped reflection of external world phenomena in the brain”).

A notable feature of a two to three year old child is the ease of developing dynamic stereotypes. Interestingly, each new stereotype is developed more easily. M. M. Koltsova writes: “Now not only the daily routine becomes important for a child: hours of sleep, wakefulness, nutrition and walks, but also the sequence in putting on or taking off clothes or the order of words in a familiar fairy tale and song - everything acquires meaning. Obviously “that when the nervous processes are not yet strong and mobile enough, children need stereotypes that facilitate adaptation to the environment.”

Conditional connections and dynamic stereotypes in children under three years of age are extremely strong, so changing them is always an unpleasant event for a child. An important condition in educational work at this time is a careful attitude towards all developed stereotypes.

The age from three to five years is characterized by further development of speech and improvement of nervous processes (their strength, mobility and balance increase), the processes of internal inhibition acquire dominant importance, but delayed inhibition and conditioned inhibition are developed with difficulty. Dynamic stereotypes are still developed just as easily. Their number increases every day, but their alteration no longer causes disturbances in higher nervous activity, which is due to the above-mentioned functional changes. The indicative reflex to extraneous stimuli is longer and more intense than in school-age children, which can be used effectively to inhibit bad habits and skills in children.

Thus, truly inexhaustible possibilities open up for the teacher’s creative initiative during this period. Many outstanding teachers (D. A. Ushinsky, A. S. Makarenko) empirically considered the age from two to five to be especially responsible for the harmonious formation of all physical and mental capabilities of a person. Physiologically, this is based on the fact that conditioned connections and dynamic stereotypes that arise at this time are exceptionally strong and are carried by a person throughout his entire life. Moreover, their constant manifestation is not necessary; they can be inhibited for a long time, but under certain conditions they are easily restored, suppressing conditioned connections developed later.

By the age of five to seven years, the role of the signal system of words increases even more, and children begin to speak freely. “A word at this age already has the meaning of a “signal of signals,” that is, it receives a general meaning close to that which it has for an adult.”

This is due to the fact that only by the seven years of postnatal development does the material substrate of the second signaling system functionally mature. In this regard, it is especially important for educators to remember that only by the age of seven can a word be effectively used to form conditional connections. Abuse of words before this age without sufficient connection with immediate stimuli is not only ineffective, but also causes functional harm to the child, forcing the child’s brain to work in non-physiological conditions.

Higher nervous activity of school-age children

The few existing physiological data indicate that primary school age (from 7 to 12 years) is a period of relatively “quiet” development of higher education. nervous activity. The strength of the processes of inhibition and excitation, their mobility, balance and mutual induction, as well as a decrease in the strength of external inhibition, provide opportunities for extensive learning of the child. This is the transition “from reflexive emotionality to intellectualization of emotions”

However, only on the basis of learning to write and read does the word become an object of the child’s consciousness, increasingly moving away from the images of objects and actions associated with it. A slight deterioration in the processes of higher nervous activity is observed only in the 1st grade in connection with the processes of adaptation to school. It is interesting to note that at primary school age, based on the development of the second signaling system, the child’s conditioned reflex activity acquires a specific character, characteristic only of humans. For example, when developing vegetative and somato-motor conditioned reflexes in children, in some cases a response is observed only to the unconditioned stimulus, while the conditioned stimulus does not cause a reaction. Thus, if the subject was given verbal instructions that after the bell he would receive cranberry juice, then salivation begins only when an unconditioned stimulus is presented. Such cases of “non-formation” of a conditioned reflex appear more often the older the age of the subject, and among children of the same age - among the more disciplined and capable.

Verbal instructions significantly accelerate the formation of conditioned reflexes and in some cases do not even require unconditional reinforcement: conditioned reflexes are formed in a person in the absence of direct stimuli. These features of conditioned reflex activity determine the enormous importance of verbal pedagogical influence in the process of educational work with primary schoolchildren.

1) Dorsal induction or Primary neurulation - period 3-4 weeks of gestation;
2) Ventral induction - period 5-6 weeks of gestation;
3) Neuronal proliferation - period 2-4 months of gestation;
4) Migration - period 3-5 months of gestation;
5) Organization - period 6-9 months of fetal development;
6) Myelination - takes place from the moment of birth and in the subsequent period of postnatal adaptation.

IN first trimester of pregnancy The following stages of development of the fetal nervous system occur:

Dorsal induction or Primary neurulation - due to individual developmental characteristics, it can vary in time, but always adheres to 3-4 weeks (18-27 days after conception) of gestation. During this period, the formation of the neural plate occurs, which, after the closure of its edges, turns into the neural tube (4-7 weeks of gestation).

Ventral induction - this stage of the formation of the fetal nervous system reaches its peak at 5-6 weeks of gestation. During this period, 3 expanded cavities appear at the neural tube (at its anterior end), from which the following are formed:

from the 1st (cranial cavity) - the brain;

from the 2nd and 3rd cavities - the spinal cord.

Due to division into three bladders, the nervous system develops further and the embryonic brain of the fetus from three bladders turns into five by division.

From the forebrain the telencephalon and interstitial brain are formed.

From the posterior cerebral vesicle - the anlage of the cerebellum and medulla oblongata.

During the first trimester of pregnancy, partial neuronal proliferation also occurs.

The spinal cord develops faster than the brain and, therefore, also begins to function faster, which is why it plays a more important role in the initial stages of fetal development.

But in the first trimester of pregnancy, the process of development of the vestibular analyzer deserves special attention. It is a highly specialized analyzer that is responsible in the fetus for the perception of movement in space and the sensation of changes in position. This analyzer is formed already at the 7th week of intrauterine development (earlier than other analyzers!), and by the 12th week nerve fibers are already approaching it. Myelination of nerve fibers begins by the time the fetus begins to move, at 14 weeks of gestation. But in order to conduct impulses from the vestibular nuclei to the motor cells of the anterior horns of the spinal cord, the vestibulo-spinal tract must be myelinated. Its myelination occurs after 1-2 weeks (15 - 16 weeks of gestation).

Therefore, thanks to the early formation vestibular reflex, when a pregnant woman moves in space, the fetus moves into the uterine cavity. At the same time, the movement of the fetus in space is an “irritating” factor for the vestibular receptor, which sends impulses for the further development of the fetal nervous system.

Fetal developmental disorders from exposure various factors during this period leads to violations vestibular apparatus in a newborn child.

Until the 2nd month of gestation, the fetus has a smooth brain surface covered with an ependymal layer consisting of medulloblasts. By the 2nd month of intrauterine development, the cerebral cortex begins to form by migrating neuroblasts into the overlying marginal layer, and thus forming the anlage gray matter brain.

All adverse factors affecting the development of the fetal nervous system in the first trimester lead to severe and, in most cases, irreversible damage functioning and further formation of the fetal nervous system.

Second trimester of pregnancy.

If in the first trimester of pregnancy the main formation of the nervous system occurs, then in the second trimester its intensive development occurs.

Neuronal proliferation is a fundamental process of ontogenesis.

At this stage of development, physiological hydrocele of the brain bubbles occurs. This happens because cerebrospinal fluid, entering the brain vesicles, expands them.

By the end of the 5th month of gestation, all the main grooves of the brain are formed, and the foramina of Luschka also appear, through which the cerebrospinal fluid exits the outer surface of the brain and washes it.

During the 4th to 5th month of brain development, the cerebellum develops intensively. It acquires its characteristic tortuosity and divides transversely, forming its main parts: the anterior, posterior and folliculonodular lobes.

Also in the second trimester of pregnancy, a stage of cell migration occurs (month 5), as a result of which zonation appears. The fetal brain becomes more similar to the brain of an adult child.

When the fetus is exposed to unfavorable factors during the second period of pregnancy, disorders occur that are compatible with life, since the formation of the nervous system took place in the first trimester. At this stage, disorders are associated with underdevelopment of brain structures.

Third trimester of pregnancy.

During this period, the organization and myelination of brain structures occurs. The furrows and convolutions are approaching the final stage of their development (7 - 8 months of gestation).

The stage of organization of nervous structures is understood as morphological differentiation and the emergence of specific neurons. In connection with the development of the cytoplasm of cells and the increase in intracellular organelles, there is an increase in the formation of metabolic products that are necessary for the development of nervous structures: proteins, enzymes, glycolipids, mediators, etc. In parallel with these processes, the formation of axons and dendrites occurs to ensure synoptic contacts between neurons.

Myelination of nervous structures begins from 4-5 months of gestation and ends by the end of the first, beginning of the second year of the child’s life, when the child begins to walk.

When exposed to unfavorable factors in the third trimester of pregnancy, as well as during the first year of life, when the processes of myelination of the pyramidal tracts end, serious violations does not arise. Slight changes in the structure are possible, which are determined only by histological examination.

Development of the cerebrospinal fluid and circulatory system of the brain and spinal cord.

In the first trimester of pregnancy (1 - 2 months of gestation), when the formation of five brain vesicles occurs, the formation of choroid plexuses in the cavity of the first, second and fifth medullary vesicle. These plexuses begin to secrete highly concentrated cerebrospinal fluid, which is, in fact, nutrient medium because of great content in its composition of protein and glycogen (exceeds 20 times in contrast to adults). Liquor - in this period is the main source nutrients for the development of nervous system structures.

While the development of brain structures is supported by cerebrospinal fluid, at 3-4 weeks of gestation the first vessels of the circulatory system are formed, which are located in the soft arachnoid membrane. Initially, the oxygen content in the arteries is very low, but during the 1st to 2nd month of intrauterine development, the circulatory system takes on a more mature appearance. And in the second month of gestation blood vessels begin to grow into the medulla, forming a circulatory network.

By the 5th month of development of the nervous system, the anterior, middle and posterior cerebral arteries, which are interconnected by anastomoses, and represent a complete structure of the brain.

The blood supply to the spinal cord comes from more sources than to the brain. Blood to the spinal cord comes from two vertebral arteries, which branch into three arterial tracts, which, in turn, run along the entire spinal cord, feeding it. The front horns receive more nutrients.

The venous system eliminates the formation of collaterals and is more isolated, which facilitates the rapid removal of metabolic end products through the central veins to the surface of the spinal cord and excretion into venous plexuses spine.

A feature of the blood supply to the third, fourth and lateral ventricles in the fetus is the wider size of the capillaries that pass through these structures. This leads to slower blood flow, which promotes more intense nutrition.

Many mothers wonder: when does the nervous system of the fetus form? Almost from the very beginning of cell laying. According to medical theories, all body systems develop unevenly in a baby. First, those systems that are most important for the future activities of the baby in the mother’s belly begin to function. The formation of the nervous system in the fetus is one of the first most important processes in the development of the body.

Already at 8-9 weeks of pregnancy, gynecologists can see the first signs of the nervous system on an echogram. The second month is marked by the baby making his first barely noticeable movements. Well, at 22-24 weeks you can accurately see a child who is sucking appendages.

At what time does the fetal nervous system develop?

The fetal nervous system emerges from a peculiar formation, which in medicine is called the neural tube. It must subsequently ensure the proper functioning of the entire body. Before the tube appears, nervous tissue, which consists of several types of cells, must grow. The first type is responsible for the basic specific functions of nerves, that is, these cells (neurons) are actually responsible for regulating the psyche. The second type provides good nutrition neurons and protects them from damage.

Nervous tissue with normal conditions The development of the child begins to develop already on the eighteenth day after fertilization of the egg. At 3-4 weeks the neural tube itself is already visible.

At what week does the fetal nervous system develop? Already on the first one! The nervous system is one of the first that must develop so that the baby can continue to grow. If with formation nerve tissue any problems arise, the fetus soon dies. Therefore, if you find out about pregnancy, try to immediately change your lifestyle.

What is a neural tube?

The formation of the nervous system in the fetus directly depends on the development of the tube. It is formed from a neural plate, which gradually closes into a tube, forming a small process - the rudiment of the future nervous system. If you examine the neural tube in section, you will notice several layers: internal, marginal and intermediate. The intermediate and marginal layers provide the production of gray and white matter spinal cord, which is then located in the spine. Several processes occur in the inner layer at once: cell division and synthesis of future material responsible for the baby’s genetics.

It takes the first weeks of pregnancy for the baby's neural tube to develop.

Development of the nervous system at 4-5 weeks of pregnancy

So, we found out at what period the fetal nervous system is formed. But what happens to her next?

The neural tube has some extensions called medullary vesicles. When the fetal nervous system is established, three brain vesicles appear. One of them turns into forebrain(it includes two hemispheres), the other - in the visual center of the head, and the third - in the rhomboid brain, which includes several more sections.

The marginal part of the neural tube also secretes new organ– neural crest, which is responsible for the development of several systems. At 4-5 weeks only visible on ultrasound black dot. So far, this is all that has managed to grow. However, this is already a lot for a child, because at that moment the cells responsible for his brain were born. At this moment for good development neurons needed folic acid. Under no circumstances should you treat your teeth in the first trimester! Any medications, even local anesthesia, can reverse the normal course of cell division in the nervous system. Because of this, the baby may be born with disabilities.

Development of the fetal nervous system at 6-12 weeks of pregnancy

When the nervous system of the fetus is formed, the mother should be at rest. The first weeks of pregnancy are important because the health of the child depends on them. Already at 7-8 weeks the baby is capable of reflexes. For example, it was noticed that when his lips came into contact with the processes, he tilted his head back, thereby protecting himself from danger. This is how a protective reflex develops. At 10 weeks, the baby is able to open his mouth if something irritates his lips. At the same time, the grasping reflex occurs when something bothers the baby’s hand.

By the twelfth week, the baby can move his toes. From this, doctors concluded that those areas of the brain that are responsible for bottom part fetal body. Until the child reaches three months of uterine age, he will not be able to fully respond to irritations. His movements will be sharp and short. This happens because excitation is still affecting small areas of the nervous system. But the fetus grows and develops, and over time its systems become more advanced.

Fetal development at 14-20 weeks of pregnancy

The norms of development of the fetal nervous system can only be determined using ultrasound. If you are told that the fetus meets all developmental standards, you don’t have to worry. But what is your child doing at this time? By the fourteenth week the baby becomes quite active. If before he could not move yet, then by the fifteenth week one can already count about 15 new movements the baby has mastered.

When the nervous system of the fetus is formed, the mother feels the first tremors of the baby. They appear at 19-20 weeks. An ultrasound can already distinguish movements of the arms and legs, as well as hiccups, swallowing, yawning and other mouth movements. Between 15 and 20 weeks, the number of synapses, the places in the nervous system to which signals are transmitted, increases. Due to this, the scope of the baby’s activities expands.

Condition of the fetus at 20-40 weeks of pregnancy

After the 20th week, when the nervous system is still developing, the fetal medulla begins to branch. This means that naked nerve cells will be covered with a layer of fat and will be able to fully function. Nerve impulses The baby will speed up, and he will soon be able to add new movements to his range of skills. The fetal limbs are the first to develop. The sense of smell improves a little later (about 24 weeks). In parallel with these changes, the brain also develops, in which a framework for nerve cells is built.

It is noteworthy that the mass of the brain accounts for up to 15% of the total mass of the fetus. After the main processes in the brain have ended, it is time for one more thing - the destruction of certain types of cells. According to scientists, there is nothing terrible in this process. This is simply how the body cleanses itself of unnecessary structures that have already done their job. So, when the nervous system of the fetus is formed, the body spends all its energy on its proper development.

Anomalies of the development of the nervous system in the fetus

When the nervous system of the fetus is formed, there may be various kinds anomalies and factors that appeared spontaneously. For example, a fertilized cell began to multiply incorrectly and as a result it was damaged. Fortunately, the percentage of such defects is very low: up to 1.5 per 1000 births. It is known for sure that the cells of the unborn baby are destroyed both from environmental factors and from genetic nature. World Organization Health care has established that the percentage of development of anomalies also depends on the nationalities and habitat of people. Here is a list of the main fetal development disorders:

Absence of spinal cord and brain. This happens when the neural tube does not close. The skull and spine in this case are greatly exposed.
Tube not closed in the head compartment. This means that the child is deprived of a brain. That is, it does not have hemispheres and subcortex. There is only midbrain. Children born with this disorder live only the first months.
Hernias brain section . Protrusions of the skull bone or its tissues are found on the baby’s head. Small hernias can be quickly removed.
Spinal hernias. They are very common - 1 in 200. Strong hair growth may be observed at the site of some hernias. Children with this disease cannot walk or relieve themselves.

The only method to combat these diseases is surgery. In some cases, doctors cannot help. The child either lives with this deviation all his life, or dies soon after birth.

Causes affecting damage to the nervous system

Any factors that influence the destruction of the fetal nervous system present a complex picture. After all, it all depends on how long this factor acted on the child, whether it was very negative, etc.

First and main reason of all central nervous system lesions is alcoholism of one of the parents. The toxins contained in alcohol settle in the body of the mother and father. When a woman has a child, all these harmful substances are transferred to new cells.
Some medications (for example, anti-convulsants) should not be taken during pregnancy at all. Therefore, if you have a disease that requires constant medication, talk to your gynecologist about it. He will definitely help you.
Damage to the fetus cannot pass without leaving a trace in the mother’s body. A woman can get sick with infectious diseases (herpes, rubella, etc.).
Also, the development of the fetal nervous system can be affected by the mother’s illnesses (diabetes, hypertension) and genetic predisposition. Such troubles lead to chromosomal abnormalities that cannot be cured.
Some defects, whether acquired or hereditary, may be mild. But they affect the overall development of the baby: autism, lack of attention, hyperactivity, different kinds depression.

Try to lead a healthy lifestyle, because a child with a disability, born as such due to your negligence, will suffer all his life.

When the nervous system of the fetus is formed, the mother must take full care of the right food, good rest and peace. Although gynecologists do not take into account the first two weeks of pregnancy, it is at this moment that your baby’s first vital systems are formed.

CHAPTER 10. DEVELOPMENT OF THE NERVOUS SYSTEM IN NEWBORN AND YOUNG CHILDREN. RESEARCH METHODOLOGY. LESION SYNDROMES

In a newborn baby reflex acts are carried out at the level of the stem and subcortical parts of the brain. By the time the child is born, the limbic system, the precentral region, especially field 4, which provides the early phases of motor reactions, the occipital lobe and field 17 are the most well formed. The temporal lobe (especially the temporo-parieto-occipital region), as well as the inferior parietal and frontal regions, are less mature. However, field 41 temporal lobe(projection field auditory analyzer) by the time of birth is more differentiated than field 22 (projection-associative).

10.1. Development of motor functions

Motor development in the first year of life is a clinical reflection of the most complex and currently insufficiently studied processes. These include:

The action of genetic factors is the composition of expressed genes that regulate the development, maturation and functioning of the nervous system, changing in a spatiotemporal manner; neurochemical composition of the central nervous system, including the formation and maturation of mediator systems (the first mediators are found in the spinal cord from 10 weeks of gestation);

Myelination process;

Macro- and microstructural formation of the motor analyzer (including muscles) in early ontogenesis.

First spontaneous movements embryos appear at the 5-6th week of intrauterine development. During this period, motor activity is carried out without the participation of the cortex big brain; segmentation of the spinal cord and differentiation of the musculoskeletal system occur. The formation of muscle tissue begins from the 4-6th week, when active proliferation occurs in the places where muscles are formed with the appearance of primary muscle fibers. The developing muscle fiber is already capable of spontaneous rhythmic activity. At the same time, the formation of neuromuscular

synapses under the influence of neuron induction (i.e., axons of developing spinal cord motor neurons grow into the muscles). In this case, each axon branches repeatedly, forming synaptic contacts with dozens of muscle fibers. Activation of muscle receptors influences the establishment of intracerebral connections in the embryo, which provides tonic stimulation of brain structures.

In the human fetus, reflexes develop from local to generalized and then to specialized reflex acts. First reflex movements appear at 7.5 weeks of gestation - trigeminal reflexes that arise from tactile stimulation of the facial area; at 8.5 weeks, lateral flexion of the neck is first noted. At the 10th week, a reflex movement of the lips is observed (the sucking reflex is formed). Subsequently, as the reflexogenic zones in the area of the lips and oral mucosa mature, complex components are added in the form of opening and closing the mouth, swallowing, stretching and compressing the lips (22 weeks), and sucking movements (24 weeks).

Tendon reflexes appear at the 18-23rd week of intrauterine life, at the same age the grasping reaction is formed, by the 25th week all unconditioned reflexes caused by upper limbs. From 10.5-11 weeks are detected reflexes from the lower extremities, primarily plantar, and a reaction such as the Babinski reflex (12.5 weeks). First irregular breathing movements chest (Cheyne-Stokes type), which appear at 18.5-23 weeks, pass into spontaneous breathing by the 25th week.

In postnatal life, improvement of the motor analyzer occurs at the micro level. After birth, thickening of the cerebral cortex in areas 6, 6a and the formation of neuronal groups continue. The first networks formed from 3-4 neurons appear at 3-4 months; after 4 years, the thickness of the cortex and the size of neurons (except for Betz cells, which grow until puberty) stabilize. The number of fibers and their thickness increase significantly. The differentiation of muscle fibers is associated with the development of spinal cord motor neurons. Only after the appearance of heterogeneity in the population of motor neurons in the anterior horns of the spinal cord does the division of muscles into motor units occur. Subsequently, at the age of 1 to 2 years, not individual muscle fibers develop, but “superstructures” - motor units consisting of muscles and nerve fibers, and changes in muscles are primarily associated with the development of the corresponding motor neurons.

After the birth of a child, as the controlling parts of the central nervous system mature, its pathways also develop, in particular, myelination of peripheral nerves occurs. At the age of 1 to 3 months, the development of the frontal and temporal regions brain The cerebellar cortex is still poorly developed, but the subcortical ganglia are clearly differentiated. Up to the midbrain region, myelination of fibers is well expressed; in the cerebral hemispheres, only sensory fibers are completely myelinated. From 6 to 9 months, long associative fibers are most intensively myelinated, and the spinal cord is completely myelinated. By the age of 1 year, myelination processes cover the long and short associative pathways of the temporal and frontal lobes and the spinal cord along its entire length.

There are two periods of intense myelination: the first of them lasts from 9-10 months of intrauterine life to 3 months of postnatal life, then from 3 to 8 months the rate of myelination slows down, and from 8 months the second period of active myelination begins, which lasts until the child learns to walk (t i.e. on average up to 1 year 2 months). With age, both the number of myelinated fibers and their content in individual peripheral nerve bundles change. These processes, most intense in the first 2 years of life, are mostly completed by 5 years.

An increase in the speed of impulse transmission along the nerves precedes the emergence of new motor skills. Thus, in the ulnar nerve, the peak increase in impulse conduction velocity (ICV) occurs in the 2nd month of life, when the child can a short time clasp your hands while lying on your back, and at the 3-4th month, when hypertonicity in the hands is replaced by hypotension, the volume increases active movements(holds objects in hand, brings them to mouth, clings to clothes, plays with toys). In the tibial nerve, the largest increase in SPI appears first at 3 months and precedes the disappearance of physiological hypertension in lower limbs, which coincides with the disappearance of automatic gait and positive ground reaction. For ulnar nerve the next increase in SPI is observed at 7 months with the appearance of the reaction of preparing to jump and the extinction of the grasping reflex; Moreover, there is a contradiction thumb, active force appears in the hands: the child shakes the bed and breaks toys. For the femoral nerve, the next increase in conduction velocity corresponds to 10 months, for the ulnar nerve - 12 months.

At this age, free standing and walking appear, hands are freed up: the child waves them, throws toys, and claps his hands. Thus, there is a correlation between an increase in SPI in peripheral nerve fibers and the development of a child’s motor skills.

10.1.1. Newborn reflexes

Newborn reflexes - this is an involuntary muscle reaction to a sensitive stimulus, they are also called: primitive, unconditioned, innate reflexes.

Unconditioned reflexes, according to the level at which they are closed, can be:

1) segmental stem (Babkina, sucking, proboscis, searching);

2) segmental spinal (grasping, crawling, support and automatic gait, Galant, Perez, Moro, etc.);

3) posotonic suprasegmental - levels of the trunk and spinal cord (asymmetric and symmetric cervical tonic reflexes, labyrinthine tonic reflex);

4) posotonic suprasegmental - the level of the midbrain (righting reflexes from head to neck, from torso to head, from head to torso, start reflex, balance reaction).

The presence and severity of the reflex is an important indicator of psychomotor development. Many newborn reflexes disappear as the child develops, but some of them can be detected in adulthood, but they have no topical significance.

The absence of reflexes or pathological reflexes in a child, a delay in the reduction of reflexes characteristic of an earlier age, or their appearance in an older child or adult indicate damage to the central nervous system.

Unconditioned reflexes are examined in the position on the back, stomach, vertically; in this case it is possible to identify:

Presence or absence, suppression or strengthening of the reflex;

Time of appearance from the moment of irritation (latency period of the reflex);

Expressiveness of the reflex;

The speed of its decline.

Unconditioned reflexes are influenced by factors such as the type of higher nervous activity, time of day, general state child.

The most constant unconditioned reflexes In the supine position:

search reflex- the child lies on his back, when stroking the corner of his mouth, he lowers himself, and his head turns in the direction of irritation; options: opening the mouth, lowering the lower jaw; the reflex is especially well expressed before feeding;

defensive reaction- painful stimulation of the same area causes the head to turn in the opposite direction;

proboscis reflex- the child lies on his back, a light, quick blow to the lips causes contraction of the orbicularis oris muscle, while the lips are extended “proboscis”;

sucking reflex- active sucking of a pacifier placed in the mouth;

palm-oral reflex (Babkina)- pressing on the thenar area of the palm causes the mouth to open, the head to tilt, and the shoulders and forearms to flex;

grasp reflex occurs when a finger is placed in the child’s open palm, while his hand covers the finger. An attempt to free the finger leads to increased gripping and suspension. In newborns, the grasp reflex is so strong that they can be lifted off the changing table if both hands are used. The inferior grasp reflex (Werkom) can be induced by pressing on the balls of the toes at the base of the foot;

Robinson reflex- when trying to free the finger, suspension occurs; this is a logical continuation of the grasping reflex;

inferior grasp reflex- plantar flexion of the fingers in response to touching the base of the II-III toes;

Babinski reflex- with line irritation of the sole of the foot, fan-shaped divergence and extension of the toes occur;

Moro reflex: Phase I - raising the arms, sometimes so pronounced that it occurs with a rotation around the axis; Phase II - return to the starting position after a few seconds. This reflex is observed when the child is suddenly shaken, loud sound; the spontaneous Moro reflex is often the cause of a child falling from the changing table;

protective reflex- when the sole is pricked, the leg flexes three times;

cross extensor reflex- an injection of the sole, fixed in an extended position of the leg, causes straightening and slight adduction of the other leg;

start reflex(extension of arms and legs in response to a loud sound).

Upright (normally, when a child is suspended vertically by the armpits, flexion occurs in all joints of the legs):

support reflex- in the presence of solid support under the feet, the torso straightens and the foot rests on the full foot;

automatic gait occurs if the child is slightly tilted forward;

rotational reflex- when rotating in a vertical suspension by the armpits, the head turns in the direction of rotation; if the head is fixed by the doctor, then only the eyes turn; after the appearance of fixation (by the end of the neonatal period), eye rotation is accompanied by nystagmus - assessment of the vestibular response.

In the prone position:

protective reflex- when placing the child on his stomach, the head turns to the side;

crawling reflex (Bauer)- lightly pushing the hand towards the feet causes repulsion from it and movements reminiscent of crawling;

talent reflex- when the skin of the back near the spine is irritated, the body bends in an arc open towards the irritant; the head turns in the same direction;

Perez reflex- when running a finger along the spinous processes of the spine from the tailbone to the neck, a painful reaction and a cry occur.

Reflexes that persist in adults:

Corneal reflex (squinting of the eye in response to touch or sudden bright light);

Sneezing reflex (sneezing when the nasal mucosa is irritated);

Gag reflex (vomiting when the back of the throat or root of the tongue is irritated);

Yawning reflex (yawning when there is a lack of oxygen);

Cough reflex.

Assessment of a child's motor development of any age is carried out at the moment of maximum comfort (warmth, satiety, peace). It should be taken into account that the child’s development occurs craniocaudally. This means that the upper parts of the body develop before the lower parts (e.g.

manipulations precede the ability to sit, which, in turn, precedes the appearance of walking). Muscle tone also decreases in the same direction - from physiological hypertonicity to hypotension by 5 months of life.

Components of motor function assessment are:

muscle tone and postural reflexes(proprioceptive reflexes of the muscular-articular apparatus). There is a close connection between muscle tone and postural reflexes: muscle tone affects posture in sleep and in a state of quiet wakefulness, and posture, in turn, affects tone. Tone options: normal, high, low, dystonic;

tendon reflexes. Options: absence or decrease, increase, asymmetry, clonus;

volume of passive and active movements;

unconditioned reflexes;

pathological movements: tremor, hyperkinesis, convulsions.

In this case, it is necessary to pay attention to the general condition of the child (somatic and social), the characteristics of his emotional background, the function of analyzers (especially visual and auditory) and the ability to communicate.

10.1.2. Development of motor skills in the first year of life

Newborn. Muscle tone. Normally, tone predominates in the flexors (flexor hypertension), and the tone in the arms is higher than in the legs. As a result of this, a “fetal position” occurs: the arms are bent at all joints, brought to the body, pressed to the chest, the hands are clenched into fists, the thumbs are clasped with the rest; the legs are bent at all joints, slightly abducted at the hips, dorsiflexed in the feet, and the spine is curved. Muscle tone is increased symmetrically. To determine the degree of flexor hypertension, the following tests are available:

traction test- the child lies on his back, the researcher takes him by the wrists and pulls him towards himself, trying to sit him up. In this case, the arms are slightly extended at the elbow joints, then the extension stops, and the child is pulled up to the arms. If the flexor tone is excessively strengthened, there is no extension phase, and the body immediately moves behind the hands; if there is insufficiency, the volume of extension increases or there is no stretching of the hands;

With normal muscle tone in a horizontal hanging position by the armpits, face down, the head is positioned in line with the body. In this case, the arms are bent and the legs are extended. When decreasing muscle tone The head and legs hang passively; when raised, there is a pronounced flexion of the arms and, to a lesser extent, the legs. When extensor tone predominates, the head is thrown back;

labyrinthine tonic reflex (LTR) occurs when the position of the head in space changes as a result of irritation of the labyrinths. At the same time, the tone in the extensors in the supine position and in the flexors in the prone position increases;

symmetrical cervical tonic reflex (SCTR)- in a supine position with a passive tilt of the head, the tone of the flexors in the arms and extensors in the legs increases; when the head is extended, the opposite reaction occurs;

asymmetric cervical tonic reflex (ASTR), Magnus-Klein reflex occurs when the head of a child lying on his back is turned to the side. At the same time, in the hand to which the child’s face is turned, the tone of the extensors increases, as a result of which it extends and moves away from the body, the hand opens. At the same time, the opposite arm is bent and its hand is clenched into a fist (fencing pose). When you turn your head, your position changes accordingly.

Volume of passive and active movements

Flexor hypertension surmountable, but limits the range of passive movements in the joints. It is impossible for a child to fully straighten his arms at the elbow joints, raise his arms above the horizontal level, or spread his hips without causing pain.

Spontaneous (active) movements: periodic bending and extension of the legs, crossing, pushing away from the support in a position on the stomach and back. Movements in the hands are performed in the elbow and wrist joints (hands clenched into fists move at chest level). The movements are accompanied by an athetoid component (a consequence of the immaturity of the striatum).

Tendon reflexes: in a newborn it is possible to evoke only knee reflexes, which are usually elevated.

Unconditioned reflexes: All reflexes of newborns are evoked, they are moderately expressed, and slowly deplete.

Posotonic reactions: the newborn lies on his stomach, his head is turned to the side (protective reflex), his limbs are bent in

all joints and brought to the body (tonic labyrinth reflex). Direction of development: exercises for holding the head upright, resting on the hands.

Walking Ability: a newborn and a child 1-2 months of age have a primitive reaction of support and automatic gait, which fades by 2-4 months of life.

Grasping and manipulation: In a newborn and a 1-month-old child, the hands are clenched into a fist, he cannot open the hand on his own, and a grasping reflex is triggered.

Social contacts: A newborn's first impressions of the world around him are based on skin sensations: warm, cold, soft, hard. The child calms down when he is picked up and fed.

Child aged 1-3 months. When assessing motor function, in addition to those listed earlier (muscle tone, postural reflexes, range of spontaneous movements, tendon reflexes, unconditioned reflexes), the initial elements of voluntary movements and coordination begin to be taken into account.

Skills:

Development of analyzer functions: fixation, tracking (visual), localization of sound in space (auditory);

Integration of analyzers: finger sucking (sucking reflex + influence of the kinesthetic analyzer), examining one’s own hand (visual-kinesthetic analyzer);

The appearance of more expressive facial expressions, a smile, and a complex of animation.

Muscle tone. Flexor hypertension gradually decreases. At the same time, the influence of postural reflexes increases - ASTR and LTR are more pronounced. The meaning of postural reflexes is to create a static posture, while the muscles are “trained” to actively (rather than reflexively) maintain this posture (for example, the upper and lower Landau reflex). As the muscles are trained, the reflex gradually fades away, as the processes of central (voluntary) regulation of posture are activated. By the end of the period, the flexion posture becomes less pronounced. When testing traction, the extension angle increases. By the end of 3 months, postural reflexes weaken and are replaced by straightening reflexes of the torso:

labyrinthine righting reflex to the head- in the tummy position, the baby’s head is located in the middle

line, a tonic contraction of the neck muscles occurs, the head rises and is held. Initially, this reflex ends with the head falling and turning to the side (the influence of the protective reflex). Gradually, the head can remain in a raised position longer and longer, while the legs are tense at first, but over time they begin to actively move; the arms are increasingly extended at the elbow joints. A labyrinthine one is formed righting reflex in an upright position (holding your head upright);

righting reflex from trunk to head- when the feet touch the support, the body straightens and the head rises;

cervical erection reaction - with passive or active rotation of the head, the torso turns.

Unconditioned reflexes still well expressed; The exception is the support and automatic gait reflexes, which gradually begin to fade. At 1.5-2 months, the child is in an upright position, placed on a hard surface, resting on the outer edges of the feet, and does not make stepping movements when bending forward.

By the end of 3 months, all reflexes weaken, which is expressed in their inconstancy, prolongation of the latent period, rapid exhaustion, and fragmentation. The Robinson reflex disappears. Moro reflexes, sucking and withdrawal are still well evoked.

Combined reflex reactions appear - a sucking reflex at the sight of a breast (kinesthetic food reaction).

The range of movements increases. The athetoid component disappears, the number of active movements increases. Arises revitalization complex. The first ones become possible purposeful movements: straightening the arms upward, raising the hands to the face, sucking fingers, rubbing the eyes and nose. At the 3rd month, the child begins to look at his hands, reach out with his hands to an object - visual blink reflex. Due to the weakening of the synergy of the flexors, flexion in the elbow joints occurs without bending the fingers, and the ability to hold an inserted object in the hand.

Tendon reflexes: in addition to the knee, the Achilles and bicipital are caused. Abdominal reflexes appear.

Posotonic reactions: During the 1st month, the child raises his head for a short time, then “drops” it. Arms bent under the chest (labyrinthine righting reflex to the head, tonic contraction of the neck muscles ends with the head falling and turning it to the side -

element of the protective reflex). Direction of development: exercise to increase the time of holding the head, extension of the arms at the elbow joint, opening of the hand. At 2 months, the child can hold his head at an angle of 45 for some time. to the surface, while the head still sways uncertainly. The angle of extension in the elbow joints increases. At 3 months, the child confidently holds his head while lying on his stomach. Support on the forearms. The pelvis is lowered.

Walking Ability: a 3-5 month old child holds his head well in an upright position, but if you try to stand him up, he tucks his legs in and hangs in the arms of an adult (physiological astasia-abasia).

Grasping and manipulation: at the 2nd month the hands are slightly open. At the 3rd month, you can put a small light rattle in the child’s hand; he grabs it and holds it in his hand, but he himself is not yet able to open his hand and release the toy. Therefore, after playing for some time and listening with interest to the sounds of the rattle that are heard when it is shaken, the child begins to cry: he gets tired of holding the object in his hand, but cannot voluntarily release it.

Social contacts: at the 2nd month a smile appears, which the child addresses to all living beings (as opposed to non-living ones).

Child aged 3-6 months. At this stage, the assessment of motor functions consists of the previously listed components (muscle tone, range of motion, tendon reflexes, unconditioned reflexes, voluntary movements, their coordination) and newly emerged general motor skills, in particular manipulation (hand movements).

Skills:

Increased period of wakefulness;

Interest in toys, looking at, grasping, bringing to the mouth;

Development of facial expressions;

The appearance of humming;

Communication with an adult: the indicative reaction turns into a revival complex or a fear reaction, a reaction to the departure of an adult;

Further integration (sensorimotor behavior);

Auditory vocal reactions;

Auditory-motor reactions (turning the head towards the call);

Visual-tactile-kinesthetic (looking at one’s own hands is replaced by looking at toys and objects);

Visual-tactile-motor (grasping objects);

Visual-motor coordination - the ability to control with one's gaze the movements of a hand reaching for a nearby object (feeling one's hands, rubbing, joining hands, touching one's head, holding a breast or bottle while sucking);

The reaction of active touch is feeling an object with the feet and grasping it with their help, stretching the arms in the direction of the object, palpating; this reaction disappears when the object-grabbing function appears;

Skin concentration reaction;

Visual localization of an object in space based on the visual-tactile reflex;

Increasing visual acuity; the child can distinguish small objects on a plain background (for example, buttons on clothes of the same color).

Muscle tone. The tone of the flexors and extensors is synchronized. Now the posture is determined by a group of reflexes that straighten the torso and voluntary motor activity. In a dream, the brush is open; ASTR, SSHTR, LTR faded away. The tone is symmetrical. Physiological hypertension is replaced by normotension.

Further formation is observed straightening reflexes of the body. In the position on the stomach, stable holding of the raised head, support on a slightly extended arm, and later support on an outstretched arm are noted. The upper Landau reflex appears in the prone position (“swimmer’s pose,” i.e., raising the head, shoulders and torso in a prone position with straightened arms). Head control in a vertical position is stable and sufficient in a supine position. A straightening reflex occurs from torso to torso, i.e. the ability to rotate the shoulder girdle relative to the pelvic girdle.

Tendon reflexes everyone is called.

Developing motor skills the following.

Attempts to pull the body towards outstretched arms.

Ability to sit with support.

The appearance of a “bridge” is an arching of the spine with support on the buttocks (feet) and head when tracking an object. Subsequently, this movement is transformed into an element of turning onto the stomach - a “block” turn.

Turn from back to stomach; at the same time, the child can rest his hands, raising his shoulders and head and looking around in search of objects.

Objects are grasped with the palm (squeezing the object in the palm using the flexor muscles of the hand). There is no opposable thumb yet.

Grasping an object is accompanied by many unnecessary movements (both arms, mouth, legs move at the same time), and there is still no clear coordination.

Gradually the number of unnecessary movements decreases. Grasping an attractive object with both hands appears.

The number of movements in the hands increases: lifting up, to the sides, clutching together, feeling, putting in the mouth.

Movements in large joints and fine motor skills are not developed.

Ability to sit independently (without support) for a few seconds/minutes.

Unconditioned reflexes fade away, with the exception of the sucking and withdrawal reflex. Elements of the Moro reflex are preserved. The appearance of the parachute reflex (in the position of hanging horizontally by the armpits, face down, as if falling, the arms are extended and the fingers are spread apart - as if in an attempt to protect yourself from falling).

Posotonic reactions: at 4 months the baby’s head is stably raised; support on an extended arm. In the future, this pose becomes more complicated: the head and shoulder girdle are raised, arms are straightened and extended forward, legs are straight (swimmer’s pose, superior Landau reflex). Raising your legs (inferior Landau reflex), The baby can rock and turn around on his stomach. At the 5th month, the ability to turn from the position described above onto the back appears. At first, turning from the stomach to the back occurs accidentally when throwing the arm far forward and disturbing the balance on the stomach. Direction of development: exercises for purposeful turns. At the 6th month, the head and shoulder girdle are raised above the horizontal surface at an angle of 80-90?, the arms are straightened at the elbow joints, the support is on fully open hands. This position is already so stable that the child can follow the object of interest by turning his head, and also transfer his body weight to one hand, and with the other hand try to reach the object and grab it.

Ability to sit - keeping the body in a static state is a dynamic function and requires the work of many muscles and clear coordination. This position allows you to free up your hands for fine motor actions. To learn to sit, you need to master three fundamental functions: holding your head upright in any position of the body, bending your hips and actively rotating your torso. At 4-5 months, when pulling the arms, the child seems to “sit down”: bends his head, arms and legs. At 6 months, the child can be seated, and for some time he will hold his head and torso upright.

Walking Ability: at 5-6 months, the ability to stand with the support of an adult, leaning on a full foot, gradually appears. At the same time, the legs are straightened. Quite often, in an upright position, the hip joints remain slightly bent, as a result of which the child does not stand on his full foot, but on his toes. This isolated phenomenon is not a manifestation of spastic hypertonicity, but a normal stage of gait formation. The “jumping phase” appears. The child begins to jump, being placed on his feet: the adult holds the child under the arms, he squats and pushes off, straightening his hips, knees and ankle joints. This causes a lot of positive emotions and is usually accompanied by loud laughter.

Grasping and manipulation: at the 4th month, the range of movements in the hand increases significantly: the child brings his hands to his face, examines them, brings them up and puts them in his mouth, rubs hand against hand, touches one hand with the other. He may accidentally grab a toy lying within his reach and also bring it to his face or mouth. Thus, he explores the toy - with his eyes, hands and mouth. At 5 months, the child can voluntarily pick up an object lying in his field of vision. At the same time, he extends both hands and touches it.

Social contacts: from 3 months the child begins to laugh in response to communication with him, a complex of revival and cries of joy appear (before this time, a cry occurs only with unpleasant sensations).

Child aged 6-9 months. During this age period the following functions are noted:

Development of integrative and sensory-situational connections;

Active cognitive activity based on visual-motor behavior;

Chain motor combination reflex - listening, observing one’s own manipulations;

Development of emotions;

Games;

Variety of facial movements. Muscle tone - fine. Tendon reflexes are evoked by all. Motor skills:

Development of voluntary purposeful movements;

Development of the straightening reflex of the torso;

Turns from stomach to back and from back to stomach;

One arm support;

Synchronization of the work of antagonist muscles;

Stable independent sitting for a long time;

Chain symmetrical reflex in the prone position (the basis of crawling);

Crawling backwards, in a circle, using pull-ups on your hands (legs are not involved in crawling);

Crawling on all fours with the body raised above the support;

Attempts to take a vertical position - when pulling the arms from a position lying on the back, one immediately stands on straightened legs;

Attempts to stand up while holding onto support with your hands;

Start walking along support (furniture);

Attempts to sit up independently from a vertical position;

Attempts to walk while holding the hand of an adult;

Plays with toys; the second and third fingers are involved in manipulations. Coordination: coordinated clear movements of the hands; at

manipulations in a sitting position, there are a lot of unnecessary movements, instability (i.e. voluntary actions with objects in a sitting position are a stress test, as a result of which the pose is not maintained and the child falls).

Unconditioned reflexes have faded away, except for sucking.

Posotonic reactions: at 7 months the child is able to turn from his back to his stomach; For the first time, based on the righting reflex of the torso, the ability to sit down independently is realized. At the 8th month, turns improve and the phase of crawling on all fours develops. At the 9th month, the ability to purposefully crawl with support on the hands appears; leaning on the forearms, the child pulls up the entire torso.

Sitting Ability: at the 7th month, the child lying on his back takes a “sitting” position, bending his legs at the hip and knee joints. In this position, the baby can play with his feet and pull them into his mouth. At 8 months, a seated child can sit independently for a few seconds, and then “fall over” to one side, leaning on the surface with one hand to protect himself from falling. At the 9th month, the child sits for a longer time on his own with a “round back” (lumbar lordosis has not yet been formed), and when tired, he leans back.

Walking Ability: At 7-8 months, a support reaction to the arms appears if the child is sharply tilted forward. At 9 months, the child, placed on the surface and supported by the hands, stands independently for several minutes.

Grasping and manipulation: At 6-8 months, the accuracy of grasping an object improves. The child takes it with the entire surface of his palm. Can transfer an object from one hand to another. At 9 months, the child randomly releases the toy from his hands, it falls, and the child carefully monitors the trajectory of its fall. He likes it when an adult picks up a toy and gives it to a child. He releases the toy again and laughs. Such an activity, in the opinion of an adult, is a stupid and meaningless game, in fact it is a complex training of hand-eye coordination and a difficult social act- playing with an adult.

Child aged 9-12 months. In this age period the following are noted:

Development and complexity of emotions; the revitalization complex fades away;

Various facial expressions;

Sensory speech, understanding simple commands;

The appearance of simple words;

Story games.

Muscle tone, tendon reflexes remain unchanged compared to the previous stage and throughout later life.

Unconditioned reflexes everything has faded away, the sucking reflex is fading away.

Motor skills:

Improving complex chain reflexes of verticalization and voluntary movements;

Ability to stand on support; attempts to stand without support, on your own;

The appearance of several independent steps, further development of walking;

Repeated actions with objects (“learning” of motor patterns), which can be considered as the first step towards the formation of complex automated movements;

Purposeful actions with objects (putting in, putting on).

Development of gait in children it is very variable and individual. Manifestations of character and personality are clearly demonstrated in attempts to stand, walk and play with toys. In most children, by the time they start walking, the Babinski reflex and the lower grasping reflex disappear.

Coordination: immaturity of coordination when taking a vertical position, leading to falls.

Improvement fine motor skills: grasping small objects with two fingers; Opposition of the thumb and little finger appears.

In the 1st year of a child’s life, the main areas of motor development are distinguished: postural reactions, elementary movements, crawling on all fours, the ability to stand, walk, sit, grasping abilities, perception, social behavior, making sounds, understanding speech. Thus, several stages are distinguished in development.

Posotonic reactions: at the 10th month, in the position on the stomach with the head raised and supported on the arms, the child can simultaneously raise the pelvis. Thus, he rests only on his palms and feet and swings back and forth. At 11 months he begins to crawl using his hands and feet. Next, the child learns to crawl in a coordinated manner, i.e. alternately taking out right hand- left leg and left hand - right leg. At the 12th month, crawling on all fours becomes more rhythmic, smooth, and fast. From this moment on, the child begins to actively master and explore his home. Crawling on all fours is a primitive form of movement, atypical for adults, but at this stage the muscles are prepared for the next stages of motor development: muscle strength increases, coordination and balance are trained.

The ability to sit develops individually from 6 to 10 months. This coincides with the development of a position on all fours (support on the palms and feet), from which the child easily sits down, turning the pelvis relative to the body ( righting reflex from the pelvic girdle to the torso). The child sits independently, stably with a straight back and legs straightened at the knee joints. In this position, the child can play for a long time without losing balance. In the future, sitting

becomes so stable that the child can perform extremely complex actions while sitting, requiring excellent coordination: for example, holding a spoon and eating with it, holding a cup with both hands and drinking from it, playing with small objects, etc.

Walking Ability: at 10 months, the child crawls to the furniture and, holding on to it, stands up independently. At 11 months, the child can walk along furniture, holding on to it. At 12 months, it becomes possible to walk while holding one hand, and finally take a few independent steps. Subsequently, the coordination and strength of the muscles involved in walking develop, and the walking itself becomes more and more improved, becoming faster and more purposeful.

Grasping and manipulation: at 10 months, a “pincer-like grip” with an opposable thumb appears. The child can take small items, while he pulls out a large and index fingers and holds the object with them like tweezers. At the 11th month, a “pincer grip” appears: the thumb and index finger form a “claw” when gripping. The difference between a pincer grip and a pincer grip is that in the former the fingers are straight, while in the latter the fingers are bent. At 12 months, the child can accurately place an object in a large dish or in the hand of an adult.

Social contacts: by the 6th month, the child distinguishes “friends” from “strangers.” At 8 months, the child begins to be afraid of strangers. He no longer allows everyone to pick him up, touch him, and turns away from strangers. At 9 months, the child begins to play hide and seek - “peek-a-boo.”

10.2. Examination of a child from the neonatal period to six months

When examining a newborn baby, its gestational age should be taken into account, because even slight immaturity or prematurity of less than 37 weeks can significantly affect the nature of spontaneous movements (movements are slow, generalized, with tremor).

Muscle tone is altered, and the degree of hypotonia is directly proportional to the degree of maturity, usually in the direction of its decrease. A full-term baby has a pronounced flexor posture (reminiscent of an embryonic one), while a premature baby has an extension posture. A full-term baby and a child with stage I prematurity, when pulling the arms, holds his head for a few seconds; children with prematurity

This problem is of a deeper degree and children with damaged central nervous system cannot hold their head. It is important to determine the severity of physiological reflexes in the neonatal period, especially grasping, hanging, as well as reflexes that ensure sucking and swallowing. When studying the function of the cranial nerves, it is necessary to pay attention to the size of the pupils and their reaction to light, the symmetry of the face, and the position of the head. Most healthy newborns fix their gaze on the 2-3rd day after birth and try to follow an object. Symptoms such as Graefe's sign and nystagmus in the extreme leads are physiological and are caused by the immaturity of the posterior longitudinal fasciculus.

Severe swelling of a child can cause depression of all neurological functions, but if it does not decrease and is combined with an enlarged liver, a congenital form of hepatocerebral dystrophy (hepatolenticular degeneration) or a lysosomal disease should be suspected.

Specific (pathognomonic) neurological symptoms characteristic of dysfunction of a particular area of the central nervous system are absent until 6 months of age. The main neurological symptoms are usually disturbances of muscle tone with or without motor deficits; communication disorders, which are determined by the ability to fix the gaze, follow objects, highlight acquaintances with a glance, etc., and reactions to various stimuli: the more clearly a child’s visual control is expressed, the more perfect his nervous system. Great importance is attached to the presence of paroxysmal epileptic phenomena or their absence.

An accurate description of all paroxysmal phenomena is more difficult the younger the child is. Convulsions that occur in this age period are often polymorphic.

The combination of altered muscle tone with movement disorders (hemiplegia, paraplegia, tetraplegia) indicates severe focal damage to the brain substance. In approximately 30% of cases of central hypotension, no cause can be found.

History and somatic symptoms have special meaning in newborns and children up to 4 months due to the paucity of neurological examination data. For example, respiratory disorders at this age can often be a consequence of damage to the central nervous system and occur when

congenital forms of myatonia and spinal amyotrophy. Apnea and respiratory rhythm disturbances can be caused by abnormalities of the brain stem or cerebellum, Pierre Robin's anomaly, as well as metabolic disorders.

10.3. Examination of a child aged 6 months to 1 year

In children from 6 months to 1 year, both acute neurological disorders with a catastrophic course and slowly progressive ones often occur, so the doctor must immediately outline the range of diseases that can lead to these conditions.

The appearance of febrile and unprovoked seizures such as infantile spasms is characteristic. Movement disorders manifested by changes in muscle tone and its asymmetry. In this age period, such congenital diseases, such as spinal amyotrophy and myopathy. The doctor must remember that the asymmetry of muscle tone in a child of this age may be due to the position of the head in relation to the body. Delays in psychomotor development may be a consequence of metabolic and degenerative diseases. Disturbances in the emotional sphere - poor facial expressions, lack of a smile and loud laughter, as well as disturbances in pre-speech development (babbling) are caused by hearing impairment, brain underdevelopment, autism, degenerative diseases of the nervous system, and when combined with skin manifestations- tuberous sclerosis, which is also characterized by motor stereotypies and convulsions.

10.4. Examination of a child after the 1st year of life

Progressive maturation of the central nervous system causes the appearance of specific neurological symptoms indicating focal damage, and dysfunction of a particular area of the central or peripheral nervous system can be determined.

The most common reasons for visiting a doctor are a delay in the formation of gait, its disturbance (ataxia, spastic paraplegia, hemiplegia, diffuse hypotonia), gait regression, and hyperkinesis.

The combination of neurological symptoms with extraneural (somatic), their slow progression, development of dysmorphia of the skull and face, lag in mental development and disturbance of emotions should prompt the doctor to think about the presence of metabolic diseases - mucopolysaccharidosis and mucolipidosis.

The second most common reason for treatment is mental retardation. Severe retardation is observed in 4 children out of 1000, and in 10-15% this delay is the cause of learning difficulties. It is important to diagnose syndromic forms in which oligophrenia is only a symptom of general underdevelopment of the brain against the background of dysmorphia and multiple developmental anomalies. Intellectual impairment can be caused by microcephaly; progressive hydrocephalus can also cause developmental delay.

Cognitive impairment in combination with chronic and progressive neurological symptoms in the form of ataxia, spasticity or hypotonia with high reflexes should lead the doctor to think about the onset of mitochondrial disease, subacute panencephalitis, HIV encephalitis (in combination with polyneuropathy), Creutzfeldt-Jakob disease. Disorders of emotions and behavior combined with cognitive deficits suggest the presence of Rett syndrome, Santavuori disease.

Neurosensory disorders (visual, oculomotor, auditory) are very widely represented in childhood. There are many reasons for their appearance. They can be congenital, acquired, chronic or developing, isolated or combined with other neurological symptoms. They can be caused by embryofetal damage to the brain, an abnormal development of the eye or ear, or the consequences of meningitis, encephalitis, tumors, metabolic or degenerative diseases.

Oculomotor disorders in some cases are a consequence of damage to the oculomotor nerves, including congenital anomaly Graefe-Moebius.

From 2 yearsThe incidence of febrile seizures sharply increases, which should completely disappear by 5 years. After 5 years, epileptic encephalopathy debuts - Lennox-Gastaut syndrome and most childhood idiopathic forms of epilepsy. Acute occurrence of neurological disorders with impaired consciousness, pyramidal and extrapyramidal neurological symptoms, debuting against the background of febrility, especially with concomitant purulent diseases in the facial area (sinusitis), should raise suspicion of bacterial meningitis, brain abscess. These conditions require urgent diagnosis and specific treatment.

At a younger age develop and malignant tumors, most often the brain stem, cerebellum and its vermis, the symptoms of which can develop acutely, subacutely, often after children stay in southern latitudes, and manifest not only as headaches, but also dizziness, ataxia due to occlusion of the cerebrospinal fluid tract.

Blood diseases are not uncommon, in particular lymphomas, which begin with acute neurological symptoms in the form of opsomyoclonus and transverse myelitis.

In children after 5 years most common cause Seeing a doctor is headache. If it is particularly persistent and chronic, accompanied by dizziness, neurological symptoms, especially cerebellar disorders (static and locomotor ataxia, intention tremor), it is necessary first to exclude a brain tumor, mainly a tumor of the posterior cranial fossa. These complaints and the listed symptoms are an indication for CT and MRI studies of the brain.

Slowly progressive development of spastic paraplegia, sensory disorders in the presence of asymmetry and body dysmorphia may raise suspicion of syringomyelia, and acute development symptoms - for hemorrhagic myelopathy. Acutely developed peripheral paralysis with radicular pain, sensory disturbances and pelvic disorders are characteristic of polyradiculoneuritis.

Delays in psychomotor development, especially in combination with the collapse of intellectual functions and progressive neurological symptoms, occur against the background of metabolic and neurodegenerative diseases at any age and have different rates of development, but in this age period it is very important to know that impairment of intellectual functions and motor skills and speech may be a consequence of epileptiform encephalopathy.

Progressive neuromuscular diseases debut at different times with gait disturbances, muscle atrophy and changes in the shape of the feet and legs.

In older children, more often in girls, episodic attacks of dizziness, ataxia with sudden blurred vision and the appearance of attacks may appear, which at first

difficult to distinguish from epileptic ones. These symptoms are accompanied by changes in the child’s affective sphere, and observations of family members and assessment of their psychological profile make it possible to reject the organic nature of the disease, although in isolated cases additional research methods are required.

They often make their debut during this period various shapes epilepsy, infections and autoimmune diseases of the nervous system, less often - neurometabolic. Circulatory disorders may also occur.

10.5. Formation of pathological postural activity and movement disorders in early organic damage brain

Impaired motor development of a child is one of the most common consequences of damage to the nervous system in the ante- and perinatal period. Delayed reduction of unconditioned reflexes leads to the formation of pathological postures and attitudes, inhibits and distorts further motor development.

As a result, all this is expressed in a violation of motor function - the appearance of a complex of symptoms, which by the 1st year is clearly formed into a child syndrome cerebral palsy. Components of the clinical picture:

Damage to motor control systems;

Delayed reduction of primitive postural reflexes;

Delay general development, including mental;

Impaired motor development, sharply enhanced tonic labyrinthine reflexes, leading to the appearance of reflex-blocking positions in which the “embryonic” posture is preserved, delayed development of extensor movements, chain symmetrical and alignment reflexes of the body;

Page 2 of 12

The nervous system regulates the physiological functions of the body in accordance with changing external conditions and maintains a certain constancy of it internal environment at a level that ensures life activity. And understanding the principles of its functioning is based on knowledge of the age-related development of brain structures and functions. In a child’s life, the constant complication of forms of nervous activity is aimed at the formation of an increasingly complex adaptive ability of the body, corresponding to the conditions of the surrounding social and natural environment.
Thus, the adaptive capabilities of a growing human body determined by the level of age-related organization of his nervous system. The simpler it is, the more primitive its answers, boiling down to simple defensive reactions. But as the structure of the nervous system becomes more complex, when the analysis of environmental influences becomes more differentiated, the child’s behavior also becomes more complex, and the level of his adaptation increases.

How does the nervous system “mature”?

In the mother's womb, the embryo receives everything it needs and is protected from any adversity. And during the maturation of the embryo, 25 thousand nerve cells are born in its brain every minute (the mechanism of this amazing process is unclear, although it is clear that a genetic program is being implemented). Cells divide and form organs while the growing fetus floats in amniotic fluid. And through the mother’s placenta he continuously, without any effort, receives food and oxygen, and toxins are removed from his body in the same way.
The fetal nervous system begins to develop from the outer germ layer, from which the neural plate, groove, and then the neural tube are first formed. In the third week, three primary brain vesicles are formed from it, two of which (anterior and posterior) divide again, resulting in the formation of five brain vesicles. From each brain vesicle, different parts of the brain subsequently develop.
Further division occurs during fetal development. The main parts of the central nervous system are formed: the hemispheres, subcortical nuclei, trunk, cerebellum and spinal cord: the main grooves of the cerebral cortex are differentiated; the predominance of the higher parts of the nervous system over the lower ones becomes noticeable.
As the fetus develops, many of its organs and systems conduct a kind of “dress rehearsal” even before their functions become truly necessary. For example, contractions of the heart muscle occur when there is still no blood and no need to pump it; peristalsis of the stomach and intestines appears, gastric juice is released, although there is no food as such yet; in complete darkness, eyes open and close; arms and legs move, which gives the mother indescribable joy from the feeling of life emerging in her; a few weeks before birth, the fetus even begins to breathe when there is no air to breathe.
By the end of the prenatal period, the general structure of the central nervous system reaches almost full development, but the adult brain is much more more complex than the brain newborn

Development of the human brain: A, B - at the stage of the brain vesicles (1 - terminal; 2 intermediate; 3 - middle, 4 - isthmus; 5 - posterior; 6 - oblong); B - embryonic brain (4.5 months); G - newborn; D - adult

The brain of a newborn makes up approximately 1/8 of the body weight and weighs on average about 400 grams (slightly more for boys). By 9 months the brain weight doubles, by the 3rd year of life it triples, and at the age of 5 the brain makes up 1/13 - 1/14 of the body weight, by the age of 20 - 1/40. The most pronounced topographic changes in various parts of the growing brain occur in the first 5-6 years of life and end only by 15-16 years.
Previously, it was believed that by the time of birth a child’s nervous system has a full set of neurons (nerve cells) and develops only due to the complication of connections between them. It is now known that in some formations of the temporal lobe of the hemispheres and cerebellum, up to 80-90% of neurons are formed only after birth with an intensity depending on the influx of sensory information (from the sense organs) from the external environment.
The activity of metabolic processes in the brain is very high. Up to 20% of all blood sent by the heart to the arteries great circle blood circulation, flows through the brain, which consumes a fifth of the oxygen absorbed by the body. High speed blood flow in cerebral vessels and its saturation with oxygen are necessary primarily for the life of cells of the nervous system. Unlike cells of other tissues, a nerve cell does not contain any energy reserves: the oxygen and nutrition supplied with the blood are consumed almost instantly. And any delay in their delivery is dangerous; if the oxygen supply is stopped for just 7-8 minutes, the nerve cells die. On average, an influx of 50-60 ml of blood per 100 g of brain matter is required per minute.

Proportions of the skull bones of a newborn and an adult

According to the increase in brain mass, significant changes occur in the proportions of the skull bones in the same way as the proportion of body parts changes during the process of growth. The skull of newborns is not fully formed, and its sutures and fontanelles may still be open. In most cases, by birth, a diamond-shaped hole at the junction of the frontal and parietal bones (the greater fontanel) remains open, which usually closes only by the age of one year; the child’s skull is actively growing, while the head increases in circumference.
This occurs most intensively in the first three months of life: the head increases in circumference by 5-6 cm. Later the pace slows down, and by the year it increases by a total of 10-12 cm. Usually in a newborn (with a weight of 3-3.5 kg ) head circumference is 35-36 cm, reaching 46-47 cm by one year. Further, head growth slows down even more (does not exceed 0.5 cm per year). Excessive head growth, as well as its noticeable lag, indicates the possibility of the development of pathological phenomena (in particular, hydrocephalus or microcephaly).
With age, the spinal cord also undergoes changes, the length of which in a newborn averages about 14 cm and doubles by the age of 10. Unlike the brain, the spinal cord of a newborn has a more functionally perfect, complete morphological structure, almost completely occupying the space spinal canal. As the vertebrae develop, the growth of the spinal cord slows down.
Thus, even with normal intrauterine development and normal childbirth, a child is born with a structurally formed, but immature nervous system.

What do reflexes give the body?

The activity of the nervous system is basically reflexive. A reflex is a response to a stimulus from the external or internal environment of the body. To implement it, a receptor with a sensory neuron that perceives irritation is required. The nervous system's response ultimately comes to motor neuron, reflexively reacting, inducing activity or “inhibiting” the organ or muscle it innervates. This simplest chain is called reflex arc, and only if it is preserved can the reflex be realized.
An example is the reaction of a newborn to a slight stroke irritation of the corner of the mouth, in response to which the child turns his head towards the source of irritation and opens his mouth. The arc of this reflex, of course, is more complex than, for example, the knee reflex, but the essence is the same: in response to irritation of the reflexogenic zone, the child appears searching movements of the head and a readiness to suck.
There are simple reflexes and complex ones. As can be seen from the example, the searching and sucking reflexes are complex, and the knee reflex is simple. At the same time, congenital (unconditioned) reflexes, especially during the newborn period, are of the nature of automatisms, mainly in the form of food, protective and postural reactions. Such reflexes in humans are provided on different “floors” of the nervous system, which is why they distinguish between spinal, brainstem, cerebellar, subcortical and cortical reflexes. In a newborn child, taking into account the unequal degree of maturity of the nervous system, reflexes of spinal and brainstem automatisms predominate.
During individual development and the accumulation of new skills due to the development of new temporary connections with the obligatory participation of the higher parts of the nervous system, conditioned reflexes are formed. Greater hemispheres The brain plays a special role in the formation of conditioned reflexes formed on the basis of innate connections in the nervous system. Therefore, unconditioned reflexes exist not only on their own, but are a constant component in all conditioned reflexes and the most complex acts of life.
If you look closely at a newborn, you will notice the erratic nature of the movements of his arms, legs, and head. The perception of irritation, for example on the leg, cold or painful, does not result in an isolated withdrawal of the leg, but in a general (generalized) motor reaction of excitation. The maturation of the structure is always expressed in the improvement of function. This is most noticeable in the formation of movements.
It is noteworthy that the first movements in a three-week-old fetus (length 4 mm) are associated with heart contractions. A motor reaction in response to skin irritation appears from the second month of intrauterine life, when the nerve elements of the spinal cord necessary for reflex activity are formed. At the age of three and a half months, most of the physiological reflexes observed in newborns can be detected in the fetus, with the exception of crying, grasping reflex and breathing. As the fetus grows and its weight increases, the volume of spontaneous movements also becomes larger, which can be easily verified by causing fetal movements by gently tapping the mother's abdomen.
In the development of a child’s motor activity, two interrelated patterns can be traced: the complication of functions and the extinction of a number of simple unconditioned, innate reflexes, which, of course, do not disappear, but are used in new, more complex movements. Delay or later extinction of such reflexes indicates a lag in motor development.
The motor activity of a newborn and a child in the first months of life is characterized by automatisms (sets of automatic movements, unconditioned reflexes). With age, automatisms are replaced by more conscious movements or skills.

Why are motor automatisms needed?

The main reflexes of motor automatism are food, protective spinal, tonic position reflexes.

Food motor automatisms provide the child with the ability to suck and search for a source of food for him. The preservation of these reflexes in a newborn indicates normal function nervous system. Their manifestation is as follows.
When pressing on the palm, the child opens his mouth, turns or bends his head. If you apply a light blow to the lips with your fingertips or a wooden stick, in response they stretch out into a tube (that’s why the reflex is called the proboscis reflex). When stroking the corner of the mouth, the child develops a search reflex: he turns his head in the same direction and opens his mouth. The sucking reflex is the main one in this group (characterized by sucking movements when a pacifier, breast nipple, or finger enters the mouth).
If the first three reflexes normally disappear by 3-4 months of life, then the sucking reflex disappears by one year. These reflexes are most actively expressed in the child before feeding, when he is hungry; after eating, they may fade somewhat, as a well-fed child calms down.

Spinal motor automatisms appear in a child from birth and persist for the first 3-4 months and then fade away.
The simplest of these reflexes is protective: if you place the baby face down on his stomach, he will quickly turn his head to the side, making it easier for himself to breathe through his nose and mouth. The essence of another reflex is that in the position on the stomach the child makes crawling movements if support is placed on the soles of the feet (for example, a palm). Therefore, the inattentive attitude of parents to this automatism can end sadly, since a child left unattended by his mother on the table may, resting his feet on something, push himself onto the floor.

Let's check the reflexes: 1 - palm-oral; 2 - proboscis; 3 - search; 4 - sucking

Parents are touched by the ability of a tiny man to lean on his legs and even walk. These are the reflexes of support and automatic walking. To check them, you should lift the child, holding him under the arms, and place him on a support. Having felt the surface with the soles of his feet, the child will straighten his legs and rest against the table. If he is leaned forward slightly, he will take a reflex step with one leg and then the other.
From birth, a child has a well-expressed grasping reflex: the ability to hold an adult’s fingers well when placed in his palm. The force with which he grasps is sufficient to support himself and he can be lifted upward. The grasping reflex in newborn monkeys allows the babies to hold themselves on the mother's body as she moves.
Sometimes parents are worried about the child's hands scattering during various manipulations with him. Such reactions are usually associated with the manifestation of an unconditioned grasping reflex. It can be caused by any stimulus of sufficient strength: patting the surface on which the child is lying, raising the straightened legs above the table, or quickly straightening the legs. In response to this, the baby spreads his arms to the sides and opens his fists, and then returns them to their original position. With increased excitability of the child, the reflex intensifies, caused by stimuli such as sound, light, simple touch or swaddling. The reflex fades after 4-5 months.

Tonic postural reflexes. Newborns and children in the first months of life exhibit reflex motor automatisms associated with changes in head position.
For example, turning it to the side leads to a redistribution of muscle tone in the limbs so that the arm and leg towards which the face is turned extend, and the opposite ones bend. In this case, movements in the arms and legs are asymmetrical. When bending the head towards the chest, the tone in the arms and legs increases symmetrically and leads them to flexion. If the child’s head is straightened, then the arms and legs will also straighten due to increased tone in the extensors.
With age, at the 2nd month, the child develops the ability to hold his head, and after 5-6 months he can turn from his back to his stomach and vice versa, as well as hold the “swallow” pose if he is supported (under the stomach) with a hand.

Let's check the reflexes: 1 - protective; 2 - crawling; 3 - support and automatic walking; 4 - grasping; 5 - hold; 6 - grasping

In the development of motor functions in a child, a descending type of development of movement can be traced, that is, first the movement of the head (in the form of its vertical position), then the child forms the supporting function of the hands. When turning from back to stomach, the head turns first, then the shoulder girdle, and then the torso and legs. Later, the child masters leg movements - support and walking.

Let's check the reflexes: 1 - asymmetrical cervical tonic; 2 - symmetrical cervical tonic; 3 - holding the head and legs in the “swallow” pose

When, at the age of 3-4 months, a child, who was previously able to lean on his legs well with support and make stepping movements, suddenly loses this ability, parents’ concern forces them to consult a doctor. Fears are often unfounded: at this age, reflex reactions of support and the step reflex disappear and are replaced by the development of vertical standing and walking skills (by 4-5 months of life). This is what the “program” looks like for a child to master movements during the first year and a half of life. Motor development provides the ability to hold the head by 1-1.5 months, purposeful movements of the arms - by 3-4 months. At about 5-6 months, the child grasps objects well in his hand and holds them, can sit and is ready to stand. At 9-10 months he will already begin to stand with support, and at 11-12 months he can move with assistance and independently. The initially unsteady gait becomes more and more stable, and by 15-16 months the child rarely falls while walking.