To control the work of the whole organism or each individual organ, the motor apparatus, the pathways of the spinal cord are required. Their main task is to deliver impulses sent by the human "computer" to the body and limbs. Any failure in the process of sending or receiving impulses of a reflex or sympathetic nature is fraught with serious pathologies of he alth and all life activity.
What are pathways in the spinal cord and brain?
The pathways of the brain and spinal cord act as a complex of neural structures. In the course of their work, impulse impulses are sent to specific areas of gray matter. In essence, impulses are signals that prompt the body to act on the call of the brain. Several groups of nerve fibers, different in accordance with functional characteristics, are the pathways of the spinal cord. These include:
- projective nerve endings;
- associative paths;
- commissural tie roots.
In addition, the performance of the spinal conductors necessitates the selection of the following classification, according to which they can be:
- motor;
- touch.
Sensitive perception and human motor activity
Sensory or sensitive pathways of the spinal cord and brain serve as an indispensable element of contact between these two most complex systems in the body. They also send an impulsive message to every organ, muscle fiber, arms and legs. The instantaneous sending of an impulse signal is a fundamental moment in the implementation by a person of coordinated coordinated body movements performed without any conscious effort. Impulses sent by the brain, nerve fibers can recognize through touch, pain, body temperature, musculoskeletal motility.
The motor pathways of the spinal cord predetermine the quality of a person's reflex reaction. Providing the sending of impulse signals from the head to the reflex endings of the ridge and the muscular apparatus, they endow a person with the ability to self-control motor skills - coordination. Also, these pathways are responsible for the transmission of stimulating impulses towards the visual and auditory organs.
Where are the pathways?
Having become familiar with the anatomical distinguishing features of the spinal cord, it is necessary to figure out where the very pathways of the spinal cord are located, because this term implies a lot of nerve matter and fibers. They are located in specific vital substances: gray and white. Connecting each otherthe spinal horns and cortex of the left and right hemispheres, conducting pathways through neural connections, provide contact between these two departments.
The functions of the conductors of the main human organs are to implement the intended tasks with the help of specific departments. In particular, the pathways of the spinal cord are within the upper vertebrae and head, which can be described in more detail as follows:
- Associative connections are a kind of "bridges" that connect the areas between the cortex of the hemispheres and the nuclei of the spinal substance. In their structure there are fibers of various sizes. Relatively short ones do not go beyond the hemisphere or its brain lobe. Longer neurons transmit impulses that travel some distance to the gray matter.
- Commissural pathways are a body with a corpus callosum and perform the task of connecting the newly formed sections in the head and spinal cord. The fibers from the main lobe radiate out, they are placed in the white spinal substance.
- Projective nerve fibers are located directly in the spinal cord. Their performance makes it possible for impulses to arise in the hemispheres in a short time and establish communication with internal organs. The division into ascending and descending pathways of the spinal cord concerns precisely fibers of this type.
Ascending and descending conductor system
The ascending pathways of the spinal cord fill the human need for vision, hearing, motor functions and their contact with importantbody systems. The receptors for these connections are located in the space between the hypothalamus and the first segments of the spinal column. The ascending pathways of the spinal cord are able to receive and send further an impulse impulse coming from the surface of the upper layers of the epidermis and mucous membranes, life-support organs.
In turn, the descending pathways of the spinal cord include the following elements in their system:
- Pyramidal neuron (originates in the cerebral cortex, then rushes down, bypassing the brain stem; each of its bundles is located on the spinal horns).
- The central neuron (it is a motor neuron, connecting the anterior horns and the cortex of the hemispheres with reflex roots; along with axons, elements of the peripheral nervous system also enter the chain).
- Spinocerebellar fibers (conductors of the lower extremities and spinal column, including the sphenoid and thin ligaments).
It is rather difficult for an ordinary person who does not specialize in the field of neurosurgery to understand the system represented by the complex pathways of the spinal cord. The anatomy of this department is indeed an intricate structure consisting of neural impulse transmissions. But it is thanks to her that the human body exists as a whole. Due to the double direction in which the conductive pathways of the spinal cord operate, instantaneous transmission of impulses is ensured, which carry information from the controlled organs.
Deep sensory conductors
The structure of the nerve cords, acting in an upward direction, is multi-component. These pathways of the spinal cord are formed by several elements:
- Burdach's bundle and Gaull's bundle (they are paths of deep sensitivity located on the back of the spinal column);
- spinothalamic bundle (located on the side of the spinal column);
- Govers' bundle and Flexig's bundle (cerebellar pathways located on the sides of the column).
Inside the intervertebral nodes are cells of neurons of a deep degree of sensitivity. The processes localized in the peripheral areas terminate in the most suitable muscle tissues, tendons, bone and cartilage fibers and their receptors.
In turn, the central processes of the cells, located behind, keep the direction towards the spinal cord. Conducting deep sensitivity, the posterior nerve roots do not go deep into the gray matter, forming only the posterior spinal columns.
Where these fibers enter the spinal cord, they are divided into short and long. Further, the pathways of the spinal cord and brain are sent to the hemispheres, where their cardinal redistribution takes place. Most of them remain in the zones of the anterior and posterior central gyri, as well as in the region of the crown.
It follows that these paths conduct sensitivity, thanks to which a person can feel how his muscular-articular apparatus works, feel any vibrational movement ortactile touch. Gaulle's bundle, located right in the center of the spinal cord, distributes sensation from the lower torso. Burdach's bundle is located above and serves as a conductor of the sensitivity of the upper limbs and the corresponding part of the body.
How to find out about the degree of sensory?
You can determine the degree of deep sensitivity with a few simple tests. For their implementation, the patient's eyes are closed. Its task is to determine the specific direction in which the doctor or researcher makes movements of a passive nature in the joints of the fingers, hands or feet. It is also desirable to describe in detail the posture of the body or the position that its limbs have assumed.
With the help of a tuning fork for vibration sensitivity, you can examine the conductive pathways of the spinal cord. The functions of this device will help to accurately determine the time during which the patient clearly feels the vibration. To do this, take the device and click on it to make a sound. At this point, it is necessary to put on any bony protrusion on the body. In the case where this sensitivity drops out earlier than in other cases, it can be assumed that the posterior pillars are affected.
The test for the sense of localization implies that the patient, closing his eyes, accurately points to the place where the researcher touched him a few seconds before. A satisfactory indicator is considered if the patient made an error within one centimeter.
Sensory susceptibility of the skin
The structure of the pathways of the spinal cord allows forperipheral level to determine the degree of skin sensitivity. The fact is that the nerve processes of the protoneuron are involved in skin receptors. The processes located in the center of the posterior processes rush directly to the spinal cord, as a result of which the Lysauer zone is formed there.
Just like the path of deep sensitivity, the skin path is made up of several successively combined nerve cells. Compared to the spinothalamic bundle of nerve fibers, information impulses transmitted from the lower extremities or lower trunk are slightly higher and in the middle.
Skin sensitivity varies according to criteria based on the nature of the stimulus. She happens:
- temperature;
- thermal;
- pain;
- tactile.
In this case, the last type of skin sensitivity, as a rule, is transmitted by conductors of deep sensitivity.
How to know about pain threshold and temperature difference?
To determine the level of pain, doctors use the injection method. In the most unexpected places for the patient, the doctor inflicts several light injections with a pin. The patient's eyes should be closed, because. he must not see what is happening.
The temperature sensitivity threshold is easy to determine. In a normal state, a person experiences various sensations at temperatures, the difference of which was about 1-2 °. To identify a pathological defect in the form of a violation of skin sensitivity, doctorsusing a special apparatus - a thermoesthesiometer. If not, you can test for warm and hot water.
Pathologies associated with disruption of pathways
In the ascending direction, the pathways of the spinal cord are formed in a position due to which a person can feel tactile touches. For the study, you need to take something soft, gentle and in a rhythmic manner conduct a subtle examination to identify the degree of sensitivity, as well as check the reaction of hairs, bristles, etc.
Skin sensitivity disorders currently considered to be:
- Anesthesia is the complete loss of skin sensation on a specific superficial area of the body. In case of violation of pain sensitivity, analgesia occurs, in case of temperature - termanesthesia.
- Hyperesthesia is the opposite of anesthesia, a phenomenon that occurs when the threshold of excitation decreases, and when it rises, hypalgesia appears.
- Incorrect perception of irritants (for example, the patient confuses cold and warm) is called dysesthesia.
- Paresthesia is a disorder that can manifest in a myriad of ways, ranging from crawling shivers, a feeling of electric shock and its passage through the entire body.
- Hyperpathy is the most pronounced. It is also characterized by damage to the thalamus, an increase in the threshold of excitability, the inability to locally determine the stimulus, a severe psycho-emotional coloring of everything that happens and toosharp motor reaction.
Features of the structure of descending conductors
The descending pathways of the brain and spinal cord include several ligaments, including:
- pyramid;
- rubro-spinal;
- vestibulo-spinal;
- reticulo-spinal;
- rear longitudinal.
All of the above elements are the motor pathways of the spinal cord, which are the components of the nerve cords in the downward direction.
The so-called pyramidal path starts from the largest cells of the same name located in the upper layer of the cerebral hemisphere, mainly in the central gyrus. The pathway of the anterior cord of the spinal cord is also located here - this important element of the system is directed downward and passes through several sections of the posterior femoral capsule. At the point of intersection of the medulla oblongata and spinal cord, an incomplete decussation can be found, forming a straight pyramidal bundle.
In the tegmentum of the midbrain there is a conducting rubro-spinal path. It starts from the red nuclei. Upon exiting, its fibers cross and pass into the spinal cord through the varoli and medulla oblongata. Rubro-spinal path allows you to conduct impulses from the cerebellum and subcortical nodes.
The pathways of the white matter of the spinal cord begin in Deiters' nucleus. Located in the brainstem, the vestibulo-spinal path continues in the spinal cord and ends in its anterior horns. The passage of impulses from the vestibular apparatus to the motor neuron depends on this conductor.peripheral system.
In the cells of the reticular formation of the hindbrain, the reticulo-spinal path begins, which is scattered in separate bundles in the white matter of the spinal cord, mainly from the side and front. In fact, this is the main connecting element between the reflex brain center and the musculoskeletal system.
The posterior longitudinal ligament is also involved in connecting motor structures to the brainstem. The work of the oculomotor nuclei and the vestibular apparatus as a whole depends on it. The posterior longitudinal bundle is located in the cervical spine.
Consequences of diseases of the spinal cord
Thus, the tracts of the spinal cord are vital connecting elements that provide a person with the ability to move and feel. The neurophysiology of these pathways is associated with the structural features of the spine. It is known that the structure of the spinal cord, surrounded by muscle fibers, has a cylindrical shape. Within the substances of the spinal cord, associative and motor reflex pathways control the functionality of all body systems.
When there is a disease of the spinal cord, mechanical damage or malformations, the conductivity between the two main centers can be significantly reduced. Violations of the pathways threaten a person with a complete cessation of motor activity and loss of sensory perception.
The main reason for the lack of impulse conduction is the death of nerveendings. The most difficult degree of conduction disturbance between the brain and spinal cord is paralysis and lack of sensation in the limbs. Then there may be problems in the work of internal organs associated with the brain with a damaged neural bundle. For example, disorders in the lower part of the spinal cord lead to uncontrolled urination and defecation processes.
Are diseases of the spinal cord and pathways treated?
Only emerging degenerative changes are almost instantly reflected in the conductive activity of the spinal cord. Inhibition of reflexes leads to pronounced pathological changes due to the death of neuronal fibers. It is impossible to completely restore the disturbed conduction areas. The disease comes on rapidly and progresses at lightning speed, so gross conduction disturbances can only be avoided if medical treatment is started in a timely manner. The sooner this is done, the more likely there will be a cessation of pathological development.
The impermeability of the passing tracts of the spinal cord needs treatment, the primary task of which will be to stop the processes of dying of nerve endings. This can be achieved only if the factors that influenced the onset of the disease are suppressed. Only after that, you can start therapy in order to restore the maximum possible sensitivity and motor functions.
Medicine treatment aims to stop the process of brain cell death. Their task is alsorestoration of impaired blood supply to the damaged area of the spinal cord. In the course of treatment, doctors take into account age-related characteristics, the nature and severity of damage and progression of the disease. In pathway therapy, it is important to maintain constant stimulation of nerve fibers with electrical impulses. This will help maintain satisfactory muscle tone.
Surgical intervention is performed to restore the conductivity of the spinal cord, so it is carried out in two directions:
- Suppression of the causes of paralysis of the activity of neural connections.
- Stimulation of the spinal cord for the speedy acquisition of lost functions.
The operation should be preceded by a complete medical examination of the whole organism. This will allow to determine the localization of the processes of degeneration of nerve fibers. In the case of severe spinal injuries, the causes of compression must first be eliminated.
