Morphofunctional features of the spinal cord. Morphofunctional characteristics of efferent formations of the central nervous system under the influence of experimental ischemia
The spinal cord consists of two symmetrical halves, separated from each other in front by a deep median fissure, and behind by a median sulcus. The spinal cord is characterized by a segmental (metameric) structure (31-33 segments); each segment is associated with a pair of anterior (ventral) and a pair of posterior (dorsal) roots.
In the spinal cord there are Gray matter located in the central part, and white matter lying on the periphery.
The outer border of the white matter of the spinal cord forms glial border membrane, consisting of fused flattened processes of astrocytes. This membrane is permeated by nerve fibers that make up the anterior and posterior roots.
Throughout the entire spinal cord in the center of the gray matter runs the central canal of the spinal cord, which communicates with the ventricles of the brain.
The gray matter on the transverse section has the appearance of a butterfly and includes front, or ventral, rear, or dorsal, and lateral, or lateral, horns. The gray matter contains the bodies, dendrites and (partly) axons of neurons, as well as glial cells. The main component of gray matter, which distinguishes it from white, are multipolar neurons. Between the bodies of neurons is neuropil- a network formed by nerve fibers and processes of glial cells.
Among all the neurons of the spinal cord, three types of cells can be distinguished:
radicular,
internal,
beam.
axons radicular cells leave the spinal cord as part of its anterior roots, these are cells of the lateral and anterior horns. offshoots internal cells end in synapses within the gray matter of the spinal cord (mainly neurons of the posterior horns). axons beam cells pass in the white matter in separate bundles of fibers that carry nerve impulses from certain nuclei of the spinal cord to its other segments or to the corresponding parts of the brain, forming pathways.
As the spinal cord develops from the neural tube, neurons are isogenetically grouped into 10 layers, or Rexeda plates. At the same time, plates I-V correspond to the posterior horns, plates VI-VII correspond to the intermediate zone, plates VIII-IX correspond to the anterior horns, plate X corresponds to the zone near the central canal. On transverse sections, nuclear groups of neurons are more clearly visible, and on sagittal sections, the lamellar structure is better seen, where neurons are grouped into Rexed columns.
Cells similar in size, structure and functional significance lie in gray matter in groups called nuclei.
AT posterior horns distinguish between a spongy layer, a gelatinous substance, the own nucleus of the posterior horn and the thoracic nucleus of Clark, Roland's nucleus with inhibitory neurons, Lissauer's zone.
Neurons spongy zone and gelatinous substance carry out a connection between the sensitive cells of the spinal ganglia and the motor cells of the anterior horns, closing the local reflex arcs.
Neurons clarke nuclei receive information from the receptors of muscles, tendons and joints (proprioceptive sensitivity) along the thickest radicular fibers and transmit it to the cerebellum, these are large multipolar neurons.
Neurons own core the posterior horn is intercalated small multipolar cells, the axons of which end within the gray matter of the spinal cord of the same side (associative cells) or the opposite side (commissural cells).
Between the posterior and lateral horns, the gray matter protrudes into the white as strands, as a result of which its mesh-like loosening is formed, which is called the mesh formation, or the reticular formation of the spinal cord.
In the intermediate zone (lateral horns) the centers of the autonomic (autonomous) nervous system are located - preganglionic cholinergic neurons of its sympathetic and parasympathetic divisions.
AT anterior horns are the largest neurons in the spinal cord. These are radicular cells, since their axons make up the bulk of the fibers of the anterior roots. In the anterior horns there are 3 types of neurons that form 5 groups of nuclei that are significant in volume (lateral - anterior and posterior groups, medial - anterior and posterior groups and the central or intermediate nucleus).
Alpha motor neurons- large neurons 100-140 microns. By function, they are motor and their axons, as part of the anterior roots, exit the spinal cord and go to the striated muscles.
Gamma motor neurons- smaller, are cells that control the strength and speed of contraction.
Renshaw cells - inhibitory cells carry out mutual inhibition of flexor and extensor motoneurons, and also carry out recurrent inhibition.
white matter The horns of the brain are divided into columns: anterior (descending), middle (mixed) and posterior (ascending). The white matter of the spinal cord is a collection of longitudinally oriented predominantly myelinated nerve fibers. Bundles of nerve fibers that communicate between different parts of the nervous system are called tracts, or pathways, of the spinal cord.
4. Reflex apparatus of the spinal cord (somatic reflex arcs)
The elementary reflex arc of the intrinsic apparatus of the spinal cord is represented by two neurons. The body of the first afferent neuron located in the spinal ganglion. Its dendrite goes to the periphery and ends with a receptor. The axon of the afferent neuron, as part of the posterior roots, enters the spinal cord, its posterior horns, and transits to the cells of the anterior horns of the spinal cord. Bodies in the anterior horns motor efferent cells- large alpha motor neurons, on which the axon of the sensitive cell ends with an axosomatic synapse. The axon of the efferent neuron leaves the spinal cord, enters into the anterior roots, then into the spinal nerve, plexus, and finally, as part of the somatic nerve, reaches effector organ(muscles, glands).
When irritation is applied (prick of a finger), the receptor apparatus (noceceptors of the skin) is irritated and a nerve impulse is generated, which is centripetally through the dendrite, the body of the afferent neuron and its axon is carried through the synaptic connection to the body of the second efferent neuron. From there, the nerve impulse centrifugally leaves the spinal cord, anterior root, nerve through the cell axon and causes excitation in the effector organ (biceps brachii), which, in turn, leads to the expected effect - pulling the hand away.
The principle of the structure and operation of vegetative reflex arcs is disassembled independently.
^ Nervous system: general morphofunctional characteristics; sources of development, classification.
The nervous system provides the regulation of all vital processes in the body and its interaction with the external environment. Anatomically, the nervous system is divided into central and peripheral. The first includes the brain and spinal cord, the second combines peripheral nerve nodes, trunks and endings.
From a physiological point of view, the nervous system is divided into somatic, which innervates the entire body, except for internal organs, vessels and glands, and autonomous, or vegetative, regulating the activity of these organs.
The nervous system develops from the neural tube and the ganglionic plate. The brain and sense organs differentiate from the cranial part of the neural tube. The spinal cord, spinal and autonomic nodes, and chromaffin tissue of the body are formed from the trunk region of the neural tube and the ganglionic plate.
The mass of cells in the lateral sections of the neural tube increases especially rapidly, while its dorsal and ventral parts do not increase in volume and retain their ependymal character. The thickened lateral walls of the neural tube are divided by a longitudinal groove into the dorsal - alar and ventral - main plate. At this stage of development, three zones can be distinguished in the lateral walls of the neural tube: the ependyma lining the canal, the mantle layer, and the marginal veil. The gray matter of the spinal cord subsequently develops from the mantle layer, and its white matter develops from the marginal veil.
Simultaneously with the development of the spinal cord, spinal and peripheral vegetative nodes are laid. The starting material for them is the cellular elements of the ganglionic plate, which differentiate into neuroblasts and glioblasts, from which neurons and mayial gliocytes of the spinal ganglia are formed. Part of the cells of the ganglionic plate migrates to the periphery to the localization of the autonomic nerve ganglia and chromaffin tissue.
^ Spinal cord: morphofunctional characteristics; structure of gray and white matter.
The gray matter on the cross section of the brain is presented in the form of the letter "H" or a butterfly. The protrusions of the gray matter are called horns. There are anterior, or ventral, posterior, or dorsal, and lateral, or lateral, horns.
The gray matter of the spinal cord consists of the bodies of neurons, unmyelinated and thin myelinated fibers and neuroglia. The main component of gray matter, which distinguishes it from white, are multipolar neurons.
The white matter of the spinal cord is a collection of longitudinally oriented predominantly myelinated fibers. The bundles of nerve fibers that communicate between different parts of the nervous system are called the pathways of the spinal cord.
Among the neurons of the spinal cord, one can distinguish: neurites, radicular cells, internal, bundle.
In the posterior horns, there are: a spongy layer, a gelatinous substance, a proper nucleus of the posterior horn and a thoracic nucleus. The posterior horns are rich in diffusely located intercalary cells. In the middle of the posterior horn is its own nucleus of the posterior horn.
The thoracic nucleus (Clark's nucleus) consists of large intercalary neurons with highly branched dendrites.
Of the structures of the posterior horn, of particular interest are the gelatinous substance, which stretches continuously along the spinal cord in plates I-IV. Neurons produce enkephalin, an opioid-type peptide that inhibits pain effects. The gelatinous substance has an inhibitory effect on the functions of the spinal cord.
The largest neurons of the spinal cord are located in the anterior horns, which have a body diameter of 100-150 microns and form nuclei of considerable volume. This is the same as the neurons of the nuclei of the lateral horns, radicular cells. These nuclei are motor somatic centers. In the anterior horns, the medial and lateral groups of motor cells are most pronounced. The first innervates the muscles of the trunk and is well developed throughout the spinal cord. The second is located in the region of the cervical and lumbar thickenings and innervates the muscles of the limbs.
^ Brain: morphofunctional characteristics.
The brain is enclosed in a reliable shell of the skull. In addition, it is covered with shells of connective tissue - hard, arachnoid and soft.
In the brain, gray and white matter are distinguished, but the distribution of these two components is much more complicated here than in the spinal cord. Most of the gray matter of the brain is located on the surface of the cerebrum and in the cerebellum, forming their cortex. A smaller part forms numerous nuclei of the brain stem.
The brainstem consists of the medulla oblongata, the pons, the cerebellum, and the structures of the midbrain and diencephalon. All nuclei of the gray matter of the brainstem are composed of multipolar neurons. There are nuclei of cranial nerves and switching nuclei.
The medulla oblongata is characterized by the presence of nuclei of the hypoglossal, accessory, vagus, glossopharyngeal, vestibulocochlear nerves. In the central region of the medulla oblongata there is an important coordination apparatus of the brain - the reticular formation.
The bridge is divided into dorsal (tire) and ventral parts. The dorsal part contains the fibers of the medulla oblongata, the nuclei of the V-VIII cranial nerves, the reticular formation of the bridge.
The midbrain consists of the roof of the midbrain (the quadrigemina), the tegmentum of the midbrain, the substantia nigra, and the legs of the brain. Substance nigra got its name from the fact that its small spindle-shaped neurons contain melanin.
In the diencephalon, the optic tubercle predominates in volume. Ventral to it is a hypothalamic (hypothalamic) region rich in small nuclei. Nerve impulses to the visual hillock from the brain go along the extrapyramidal motor pathway.
^ Cerebellum: structure and morphofunctional characteristics.
The bulk of the gray matter in the cerebellum is located on the surface and forms its cortex. A smaller part of the gray matter lies deep in the white matter in the form of central nuclei. Three layers are distinguished in the cerebellar cortex: the outer one is the molecular layer, the middle one is the ganglionic layer, and the inner one is the granular one.
The ganglionic layer contains pear-shaped neurons. They have neurites, which, leaving the cerebellar cortex, form the initial link of its efferent inhibitory pathways.
The molecular layer contains two main types of neurons: basket and stellate. Basket neurons are located in the lower third of the molecular layer. These are irregularly shaped small cells about 10-20 microns in size. Their thin long dendrites branch mainly in a plane located transversely to the gyrus. The long neurites of the cells always run across the gyrus and parallel to the surface above the pear-shaped neurons. The activity of the neurites of the basket neurons causes inhibition of the piriform neurons.
The stellate neurons lie above the basket cells and are of two types. Small stellate neurons are equipped with thin short dendrites and weakly branched neurites that form synapses on the dendrites of pear-shaped cells. Large stellate neurons, unlike small ones, have long and highly branched dendrites and neurites.
Basket and stellate neurons of the molecular layer are a single system of intercalary neurons that transmit inhibitory nerve impulses to the dendrites and bodies of pear-shaped cells in a plane transverse to the gyrus. The granular layer is very rich in neurons. The first type of cells in this layer can be considered granular neurons, or granule cells. They have a small volume. The cell has 3-4 short dendrites. The dendrites of granule cells form characteristic structures called cerebellar glomeruli.
The second type of cells in the granular layer of the cerebellum are inhibitory large stellate neurons. There are two types of such cells: with short and long neurites.
The third type of cells are spindle-shaped horizontal cells. They are found predominantly between the granular and ganglionic layers. Afferent fibers entering the cerebellar cortex are represented by two types - mossy and so-called climbing fibers. Mossy fibers are part of the olivocerebellar and cerebellopontine tracts. They end in the glomeruli of the granular layer of the cerebellum, where they come into contact with the dendrites of the granule cells.
Climbing fibers enter the cerebellar cortex, apparently, along the dorsal-cerebellar and vestibulocerebellar pathways. Climbing fibers transmit excitation directly to piriform neurons.
The cerebellar cortex contains various glial elements. The granular layer contains fibrous and protoplasmic astrocytes. All layers in the cerebellum contain oligodendrocytes. The granular layer and white matter of the cerebellum are especially rich in these cells. Glial cells with dark nuclei lie in the ganglion layer between pear-shaped neurons. Microglia are found in large quantities in the molecular and ganglionic layers.
^ The subject and tasks of human embryology.
In embryogenesis, 3 sections are distinguished: pre-embryonic, embryonic and early post-embryonic.
Actual tasks of embryology are the study of the influence of various endogenous and exogenous factors of the microenvironment on the development and structure of germ cells, tissues, organs and systems.
^ Medical Embryology.
Medical embryology studies the patterns of development of the human embryo. Particular attention in the course of histology with embryology is drawn to the sources and mechanisms of tissue development, metabolic and functional features of the mother-placenta-fetus system, which make it possible to establish the causes of deviations from the norm, which is of great importance for medical practice.
Knowledge of human embryology is necessary for all doctors, especially those working in the field of obstetrics. This helps in diagnosing disorders in the mother-fetus system, identifying the causes of deformities and diseases in children after birth.
Currently, knowledge of human embryology is used to uncover and eliminate the causes of infertility, the birth of "test-tube" children, transplantation of fetal organs, the development and use of contraceptives. In particular, the problems of culturing eggs, in vitro fertilization and implantation of embryos in the uterus have become topical.
The process of human embryonic development is the result of a long evolution and to a certain extent reflects the features of the development of other representatives of the animal world. Therefore, some of the early stages of human development are very similar to similar stages in the embryogenesis of lower organized chordates.
Human embryogenesis is a part of its ontogenesis, including the following main stages: I - fertilization, and the formation of a zygote; II - crushing and formation of the blastula (blastocyst); III - gastrulation - the formation of germ layers and a complex of axial organs; IV - histogenesis and organogenesis of germinal and extra-embryonic organs; V - systemogenesis.
Embryogenesis is closely related to progenesis (development and maturation of germ cells) and the early postembryonic period. Thus, the formation of tissues begins in the embryonic period and continues after the birth of a child.
^ Sex cells: the structure and functions of male and female germ cells, the main stages of their development.
The spermatozoon is covered with a cytolemma, which in the anterior section contains a receptor - glycosyltransferase, which ensures recognition of egg receptors.
The spermatozoon head includes a small dense nucleus with a haploid set of chromosomes containing nucleoprotamines and nucleohistones. The anterior half of the nucleus is covered with a flat sac that forms the cap of the spermatozoon. The acrosome is located in it (from the Greek asgop - top, soma - body). The acrosome contains a set of enzymes, among which an important place belongs to hyaluronidase and proteases. The human sperm nucleus contains 23 chromosomes, one of which is sexual (X or Y), the rest are autosomes. The tail section of the spermatozoon consists of an intermediate, main and terminal parts.
The intermediate part contains 2 central and 9 pairs of peripheral microtubules surrounded by a helical mitochondria. Paired protrusions, or “handles”, consisting of another protein, dynein, depart from the microtubules. Dynein breaks down ATP.
The main part (pars principalis) of the tail resembles a cilium in structure with a characteristic set of microtubules in the axoneme (9 * 2) + 2, surrounded by circularly oriented fibrils that give elasticity, and a plasma membrane.
The terminal, or final, part of the spermatozoon contains single contractile filaments. The movements of the tail are whip-like, which is due to the successive contraction of microtubules from the first to the ninth pair.
In the study of sperm in clinical practice, various forms of spermatozoa are counted in stained smears, counting their percentage (spermogram).
According to the World Health Organization (WHO), the normal characteristics of human sperm are the following: concentration 20-200 million/ml, content more than 60% of normal forms. Along with normal forms, human sperm always contains abnormal ones - biflagellated, with defective head sizes (macro and microforms), with an amorphous head, with fused heads, immature forms (with remnants of the cytoplasm in the neck and tail), with flagellum defects.
Oocytes, or oocytes (from Latin ovum - egg), mature in an immeasurably smaller amount than spermatozoa. In a woman during the sexual cycle B4-28 days), as a rule, one egg matures. Thus, during the childbearing period, about 400 mature eggs are formed.
The release of an oocyte from the ovary is called ovulation. The oocyte that comes out of the ovary is surrounded by a crown of follicular cells, the number of which reaches 3-4 thousand. It is picked up by the fringes of the fallopian tube (oviduct) and moves along it. Here the maturation of the germ cell ends. The egg cell has a spherical shape, a larger cytoplasmic volume than that of a sperm cell, and does not have the ability to move independently.
The classification of eggs is based on the signs of the presence, quantity and distribution of the yolk (lecithos), which is a protein-lipid inclusion in the cytoplasm used to nourish the embryo.
There are yolkless (alecital), low yolk (oligolecital), medium yolk (mesolecithal), multiyolk (polylecital) eggs.
In humans, the presence of a small amount of yolk in the egg is due to the development of the embryo in the mother's body.
Structure. The human egg has a diameter of about 130 microns. Adjacent to the cytolemma is a shiny, or transparent, zone (zona pellucida - Zp) and then a layer of follicular cells. The nucleus of the female germ cell has a haploid set of chromosomes with an X-sex chromosome, a well-defined nucleolus, and there are many pore complexes in the karyolemma. During the period of oocyte growth, intensive processes of mRNA and rRNA synthesis take place in the nucleus.
In the cytoplasm, the protein synthesis apparatus (endoplasmic reticulum, ribosomes) and the Golgi apparatus are developed. The number of mitochondria is moderate, they are located near the yolk nucleus, where there is an intensive synthesis of the yolk, the cell center is absent. The Golgi apparatus in the early stages of development is located near the nucleus, and in the process of egg maturation it shifts to the periphery of the cytoplasm. Here are the derivatives of this complex - cortical granules, the number of which reaches about 4000, and the size is 1 micron. They contain glycosaminoglycans and various enzymes (including proteolytic ones), participate in the cortical reaction, protecting the egg from polyspermy.
The transparent, or shiny, zone (zona pellucida - Zp) consists of glycoproteins and glycosaminoglycans. The shiny zone contains tens of millions of Zp3 glycoprotein molecules, each of which has more than 400 amino acid residues connected to many oligosaccharide branches. Follicular cells take part in the formation of this zone: the processes of follicular cells penetrate through the transparent zone, heading towards the cytolemma of the egg. The cytolemma of the egg has microvilli located between the processes of the follicular cells. Follicular cells perform trophic and protective functions.
Represents flattened strand located in the spinal canal, about 45 cm long in men and 42 cm in women. In places where the nerves exit to the upper and lower extremities, the spinal cord has two thickenings: cervical and lumbar.
The spinal cord is made up of two types of fabric: outer white (bundles of nerve fibers) and inner gray matter (nerve cell bodies, dendrites and synapses). In the center of the gray matter, a narrow channel with cerebrospinal fluid runs along the entire brain. The spinal cord has segmental structure(31-33 segments), each of its sections is associated with a specific part of the body, 31 pairs of spinal cords depart from the segments of the spinal cord nerves: 8 pairs of cervical (Ci-Cviii), 12 pairs of thoracic (Thi-Thxii), 5 pairs of lumbar (Li-Lv), 5 pairs of sacral (Si-Sv) and a pair of coccygeal (Coi-Coiii).
Each nerve divides into front and back roots. back roots- afferent pathways front roots efferent pathways. Afferent impulses from the skin, motor apparatus, and internal organs enter the spinal cord along the posterior roots of the spinal nerves. The anterior roots are formed by motor nerve fibers and transmit efferent impulses to the working organs. Sensory nerves predominate over motor nerves, so there is a primary analysis of incoming afferent signals and the formation of reactions that are most important for the body at the moment (the transmission of numerous afferent impulses to a limited number of efferent neurons is called convergence).
Total spinal cord neurons is about 13 million. They are subdivided: 1) according to the department of the nervous system - neurons of the somatic and autonomic NS; 2) by appointment - efferent, afferent, insertion; 3) by influence - excitatory and inhibitory.
Functions of neurons in the spinal cord.
Efferent neurons belong to the somatic nervous system and innervate skeletal muscles - motor neurons. There are alpha and gamma motor neurons. A-motor neurons carry out transmission of signals from the spinal cord to skeletal muscles. The axons of each motor neuron divide many times, so each of them covers many muscle fibers, forming a motor motor unit with it. G-motor neurons innervate the muscle fibers of the muscle spindle. They have a high frequency of impulses, receive information about the state of the muscle spindle through intermediate neurons (intercalary). Generate pulses with a frequency of up to 1000 per second. These are phonoactive neurons with up to 500 synapses on their dendrites.
Afferent neurons somatic NS are localized in the spinal ganglia and ganglia of the cranial nerves. Their processes conduct impulses from muscle, tendon, and skin receptors, enter the corresponding segments of the spinal cord, and connect by synapses with intercalary or alpha motor neurons.
Function intercalary neurons consists in the organization of communication between the structures of the spinal cord.
Neurons of the autonomic nervous system are intercalary . Sympathetic neurons located in the lateral horns of the thoracic spinal cord, they have a rare impulse frequency. Some of them are involved in maintaining vascular tone, others in the regulation of the smooth muscles of the digestive system.
The collection of neurons forms the nerve centers.
The spinal cord contains control centers most internal organs and skeletal muscles. Centers skeletal muscle control are located in all parts of the spinal cord and innervate, according to the segmental principle, the skeletal muscles of the neck (Ci-Civ), diaphragm (Ciii-Cv), upper limbs (Cv-Thii), trunk (Thiii-Li), lower limbs (Lii-Sv). When certain segments of the spinal cord or its pathways are damaged, specific motor and sensory disorders develop.
Functions of the spinal cord:
A) provides a two-way connection between the spinal nerves and the brain - a conductive function;
B) carries out complex motor and vegetative reflexes - a reflex function.
To control the work of internal organs, motor functions, timely receipt and transmission of sympathetic and reflex impulses, the pathways of the spinal cord are used. Violations in the transmission of impulses leads to serious malfunctions in the work of the whole organism.
What is the conduction function of the spinal cord
The term "conducting pathways" means a set of nerve fibers that provide signal transmission to various centers of gray matter. The ascending and descending tracts of the spinal cord perform the main function - the transmission of impulses. It is customary to distinguish three groups of nerve fibers:- Associative pathways.
- Commissary connections.
- Projective nerve fibers.
Sensory and motor pathways provide a strong relationship between the spinal cord and brain, internal organs, the muscular system and the musculoskeletal system. Due to the rapid transmission of impulses, all body movements are carried out in a coordinated manner, without tangible effort on the part of the person.
What are the conducting tracts of the spinal cord formed by?
The main pathways are formed by bundles of cells - neurons. This structure provides the necessary speed of pulse transmission.The classification of the pathways depends on the functional characteristics of the nerve fibers:
- Ascending pathways of the spinal cord - read and transmit signals: from the skin and mucous membranes of a person, life-support organs. Ensure the performance of the functions of the musculoskeletal system.
- Descending pathways of the spinal cord - transmit impulses directly to the working organs of the human body - muscle tissues, glands, etc. Connected directly to the cortical part of the gray matter. The transmission of impulses occurs through the spinal neural connection to the internal organs.
The spinal cord has a double direction of conducting paths, which provides a fast impulse transmission of information from controlled organs. The conductive function of the spinal cord is carried out due to the presence of an effective transmission of impulses through the nervous tissue.
In medical and anatomical practice, it is customary to use the following terms: 
Where are the pathways of the spinal cord located?
All nervous tissues are located in the gray and white matter, connect the spinal horns and the cerebral cortex.The morphofunctional characteristic of the descending pathways of the spinal cord limits the direction of impulses in only one direction. Synapses are irritated from the presynaptic to the postsynaptic membrane.
The conduction function of the spinal cord and brain corresponds to the following possibilities and the location of the main ascending and descending pathways:
- Associative pathways - are "bridges" connecting the areas between the cortex and the nuclei of gray matter. Composed of short and long fibers. The first are located within one half or lobe of the cerebral hemispheres.
Long fibers are able to transmit signals through 2-3 segments of the gray matter. In the cerebrospinal substance, neurons form intersegmental bundles. - Commissural fibers - form the corpus callosum, connecting the newly formed sections of the spinal cord and brain. Disperse in a radiant way. They are located in the white matter of the brain tissue.
- Projection fibers - the location of the pathways in the spinal cord allows impulses to reach the cerebral cortex as quickly as possible. By their nature and functional features, the projection fibers are divided into ascending (afferent pathways) and descending.
The first are divided into exteroceptive (vision, hearing), proprioceptive (motor functions), interoreceptive (communication with internal organs). The receptors are located between the spinal column and the hypothalamus.
The anatomy of the pathways is quite complicated for a person who does not have a medical education. But neural transmission of impulses is what makes the human body a single whole.
The consequences of damage to the pathways
To understand the neurophysiology of the sensory and motor pathways, it is necessary to become familiar with the anatomy of the spine. The spinal cord has a structure much like a cylinder surrounded by muscle tissue.
Inside the gray matter are conductive paths that control the functioning of internal organs, as well as motor functions. Associative pathways are responsible for pain and tactile sensations. Motor - for the reflex functions of the body.
As a result of injury, malformations or diseases of the spinal cord, conduction may decrease or stop completely. This happens due to the death of nerve fibers. For a complete violation of the conduction of impulses of the spinal cord is characterized by paralysis, lack of sensitivity of the limbs. Failures in the work of internal organs begin, for which the damaged neural connection is responsible. So, with damage to the lower part of the spinal cord, urinary incontinence and spontaneous defecation are observed.
The reflex and conduction activity of the spinal cord is disturbed immediately after the onset of degenerative pathological changes. There is a death of nerve fibers that are difficult to restore. The disease progresses rapidly and a gross violation of conduction occurs. For this reason, it is necessary to start medical treatment as early as possible.
How to restore patency in the spinal cord
The treatment of non-conductivity is primarily associated with the need to stop the death of nerve fibers, as well as to eliminate the causes that have become a catalyst for pathological changes.Medical treatment
It consists in the appointment of drugs that prevent the death of brain cells, as well as sufficient blood supply to the damaged area of the spinal cord. This takes into account the age-related features of the conductive function of the spinal cord, as well as the severity of the injury or disease.For additional stimulation of nerve cells, electrical impulse treatment is performed to help maintain muscle tone.
Surgery
The operation to restore the conduction of the spinal cord affects two main areas:- Elimination of catalysts that caused the paralysis of neural connections.
- Spinal cord stimulation to restore lost functions.
Traditional medicine for conduction disorders
Folk remedies for impaired conduction of the spinal cord, if used, should be used with extreme caution so as not to worsen the patient's condition.Particularly popular are: 
It is quite difficult to completely restore neural connections after an injury. Much depends on a quick appeal to a medical center and qualified assistance from a neurosurgeon. The more time passes from the onset of degenerative changes, the less chance there is to restore the functionality of the spinal cord.
The cerebellum is the central organ of balance and coordination of movements. It is formed by two hemispheres with a large number of grooves and convolutions, and a narrow middle part - a worm.
The bulk of the gray matter in the cerebellum is located on the surface and forms its cortex. A smaller part of the gray matter lies deep in the white matter in the form of the central nuclei of the cerebellum.
There are 3 layers in the cerebellar cortex: 1) the outer molecular layer contains relatively few cells, but many fibers. It distinguishes between basket and stellate neurons, which are inhibitory. Star-shaped - slow down vertically, basket-shaped - send axons over long distances, which end on the bodies of pear-shaped cells. 2) The middle ganglionic layer is formed by one row of large pear-shaped cells, first described by the Czech scientist Jan Purkinje. The cells have a large body, 2-3 short dendrites extend from the top, which branch in a small layer. 1 axon departs from the base, which goes into the white matter to the cerebellar nuclei. 3) The inner granular layer is characterized by a large number of tightly lying cells. Among the neurons, granule cells, Golgi cells (stellate), and fusiform horizontal neurons are distinguished here. Granule cells are small cells that have short dendrites, the latter forming excitatory synapses with mossy fibers in the cerebellar glamelurs. The granule cells excite the mossy fibers, and the axons go into the molecular layer and transmit information to the piriform cells and all the fibers located there. It is the only excitatory neuron in the cerebellar cortex. Golgi cells lie under the bodies of pear-shaped neurons, axons go to the cerebellar glameruli, and can inhibit impulses from mossy fibers to granule cells.
Afferent pathways enter the cerebellar cortex through 2 types of fibers: 1) liana-shaped (climbing) - they rise from the white matter through the granular and ganglionic layers. They reach the molecular layer, form synapses with the dendrites of pear-shaped cells and excite them. 2) Bryophytes - from the white matter they enter the granular layer. Here they form synapses with the dendrites of granular cells, and the axons of granular cells go into the molecular layer, forming synapses with the dendrites of pear-shaped neurons, which form inhibitory nuclei.
The cerebral cortex. Development, neural composition and layered organization. The concept of cyto- and myeloarchitectonics. Blood-brain barrier. Structural and functional unit of the cortex.
The cerebral cortex is the highest and most complexly organized nerve center of the screen type, whose activity ensures the regulation of various body functions and complex forms of behavior. The cortex is made up of a layer of gray matter. Gray matter contains nerve cells, nerve fibers, and neuroglial cells.
Among the multipolar neurons of the cortex, pyramidal, stellate, fusiform, arachnid, horizontal, "candelabra" cells, cells with a double bouquet of dendrites, and some other types of neurons are distinguished.
Pyramidal neurons constitute the main and most specific form for the cortex of the hemispheres. They have an elongated cone-shaped body, the apex of which faces the surface of the cortex. Dendrites extend from the apex and lateral surfaces of the body. Axons originate from the base of the pyramidal cells.
Pyramidal cells of different layers of the cortex differ in size and have different functional significance. Small cells are intercalary neurons. The axons of the large pyramids take part in the formation of motor pyramidal pathways.
The neurons of the cortex are located in unsharply demarcated layers, which are designated by Roman numerals and numbered from outside to inside. Each layer is characterized by the predominance of any one type of cell. There are six main layers in the cerebral cortex:
I - The molecular layer of the cortex contains a small number of small associative horizontal Cajal cells. Their axons run parallel to the surface of the brain as part of the tangential plexus of nerve fibers of the molecular layer. However, the bulk of the fibers of this plexus is represented by branching of the dendrites of the underlying layers.
II - The outer granular layer is formed by numerous small pyramidal and stellate neurons. The dendrites of these cells rise into the molecular layer, and the axons either go into the white matter, or, forming arcs, also enter the tangential plexus of fibers of the molecular layer.
III - The widest layer of the cerebral cortex is pyramidal. It contains pyramidal neurons, and spindle cells. The apical dendrites of the pyramids go into the molecular layer, the lateral dendrites form synapses with adjacent cells of this layer. The axon of the pyramidal cell always departs from its base. In small cells, it remains within the cortex; in large cells, it forms a myelin fiber that goes to the white matter of the brain. Axons of small polygonal cells are sent to the molecular layer. The pyramidal layer performs mainly associative functions.
IV - The inner granular layer in some areas of the cortex is very strongly developed (for example, in the visual and auditory cortex), while in others it may be almost absent (for example, in the precentral gyrus). This layer is formed by small stellate neurons. It consists of a large number of horizontal fibers.
V - The ganglionic layer of the cortex is formed by large pyramids, and the region of the motor cortex (precentral gyrus) contains giant pyramids, which were first described by the Kyiv anatomist V. A. Bets. The apical dendrites of the pyramids reach the 1st layer. The axons of the pyramids are projected to the motor nuclei of the brain and spinal cord. The longest axons of Betz cells in the pyramidal pathways reach the caudal segments of the spinal cord.
VI - The layer of polymorphic cells is formed by neurons of various shapes (fusiform, stellate). The axons of these cells go into the white matter as part of the efferent pathways, and the dendrites reach the molecular layer.
Cytoarchitectonics - features of the location of neurons in different parts of the cerebral cortex.
Among the nerve fibers of the cerebral cortex, one can single out associative fibers that connect individual parts of the cortex of one hemisphere, commissural fibers that connect the cortex of different hemispheres, and projection fibers, both afferent and efferent, that connect the cortex with the nuclei of the lower parts of the central nervous system.
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