Spinal cord and spinal nerves. What is the spinal cord and where is it located? What is the human spinal cord responsible for?

The spinal cord is a section of the central nervous system of the spine, which is a cord 45 cm long and 1 cm wide.

Structure of the spinal cord

The spinal cord is located in the spinal canal. Behind and in front there are two grooves, thanks to which the brain is divided into right and left halves. It is covered with three membranes: vascular, arachnoid and hard. The space between the choroid and arachnoid membranes is filled with cerebrospinal fluid.

In the center of the spinal cord you can see gray matter, shaped like a butterfly when cut through. Gray matter consists of motor and interneurons. The outer layer of the brain is white matter of axons collected in descending and ascending pathways.

There are two types of horns in the gray matter: anterior, which contains motor neurons, and posterior, where interneurons are located.

The structure of the spinal cord has 31 segments. From each of them extend the anterior and posterior roots, which, merging, form the spinal nerve. When they leave the brain, the nerves immediately split into roots - posterior and anterior. The dorsal roots are formed with the help of axons of afferent neurons and they are directed into the dorsal horns of the gray matter. At this point they form synapses with efferent neurons, whose axons form the anterior roots of the spinal nerves.

The dorsal roots contain the spinal nodes, which contain sensory nerve cells.

The spinal canal runs through the center of the spinal cord. To the muscles of the head, lungs, heart, thoracic organs and upper extremities, nerves arise from segments of the upper thoracic and cervical parts of the brain. The abdominal organs and trunk muscles are controlled by the lumbar and thoracic segments. The muscles of the lower abdominal cavity and the muscles of the lower extremities are controlled by the sacral and lower lumbar segments of the brain.

Functions of the spinal cord

There are two main functions of the spinal cord:

• Conductor;
• Reflex.

The conductor function is that nerve impulses move along the ascending pathways of the brain to the brain, and commands are sent through the descending pathways from the brain to the working organs.

The reflex function of the spinal cord is that it allows you to perform the simplest reflexes (knee reflex, withdrawal of the hand, flexion and extension of the upper and lower extremities, etc.).

Only simple motor reflexes are carried out under the control of the spinal cord. All other movements, such as walking, running, etc., require the participation of the brain.

Spinal cord pathologies

Based on the causes of spinal cord pathologies, three groups of spinal cord diseases can be distinguished:

• Developmental defects – postnatal or congenital abnormalities in the structure of the brain;
• Diseases caused by tumors, neuroinfections, spinal circulatory disorders, hereditary diseases of the nervous system;
• Spinal cord injuries, which include bruises and fractures, compression, concussions, dislocations and hemorrhages. They can appear either independently or in combination with other factors.

Any disease of the spinal cord has very serious consequences. A special type of disease includes spinal cord injuries, which, according to statistics, can be divided into three groups:

• Car accidents are the most common cause of spinal cord injury. Driving motorcycles is especially dangerous because there is no backrest to protect the spine.
• A fall from a height can be either accidental or intentional. In any case, the risk of spinal cord damage is quite high. Often athletes, fans of extreme sports and jumping from heights get injured in this way.
• Everyday and extraordinary injuries. They often occur as a result of going down and falling in the wrong place, falling down the stairs or when there is ice. This group also includes knife and bullet wounds and many other cases.

With spinal cord injuries, the conduction function is primarily disrupted, which leads to very disastrous consequences. For example, damage to the brain in the cervical region leads to the fact that brain functions are preserved, but they lose connections with most organs and muscles of the body, which leads to paralysis of the body. The same disorders occur when peripheral nerves are damaged. If the sensory nerves are damaged, sensation in certain areas of the body is impaired, and damage to the motor nerves impairs the movement of certain muscles.

Most nerves are of a mixed nature, and their damage causes both the inability to move and loss of sensation.

Spinal cord puncture

A spinal puncture involves inserting a special needle into the subarachnoid space. A puncture of the spinal cord is performed in special laboratories, where the patency of this organ is determined and the pressure of the cerebrospinal fluid is measured. The puncture is performed for both therapeutic and diagnostic purposes. It allows you to timely diagnose the presence of hemorrhage and its intensity, find inflammatory processes in the meninges, determine the nature of the stroke, and determine changes in the nature of the cerebrospinal fluid, signaling diseases of the central nervous system.

Often a puncture is performed to administer radiopaque and medicinal fluids.

For therapeutic purposes, a puncture is performed to extract blood or purulent fluid, as well as to administer antibiotics and antiseptics.

Indications for spinal cord puncture:

• Meningoencephalitis;
• Unexpected hemorrhages in the subarachnoid space due to rupture of an aneurysm;
• Cysticercosis;
• Myelitis;
• Meningitis;
• Neurosyphilis;
• Traumatic brain injury;
• Liquororrhea;
• Echinococcosis.

Sometimes, during brain surgery, spinal cord puncture is used to reduce intracranial pressure parameters, as well as to facilitate access to malignant neoplasms.

The spinal cord is part of the central nervous system and has a direct connection with the internal organs, skin and muscles of a person. In appearance, the spinal cord resembles a cord that occupies a place in the spinal canal. Its length is about half a meter, and its width usually does not exceed 10 millimeters.

The spinal cord is divided into two parts - right and left. On top of it there are three membranes: hard, soft (vascular) and arachnoid. Between the last two there is a space filled with cerebrospinal fluid. In the central region of the spinal cord, gray matter can be found that, in a horizontal section, resembles a “moth” in appearance. Gray matter is formed from the bodies of nerve cells (neurons), the total number of which reaches 13 million. Cells similar in structure and having the same functions create the nuclei of gray matter. There are three types of projections (horns) in the gray matter, which are divided into the anterior, posterior and lateral horn of the gray matter. The anterior horns are characterized by the presence of large motor neurons, the posterior horns are formed by small interneurons, and the lateral horns are the location of the visceral motor and sensory centers.

The white matter of the spinal cord surrounds the gray matter on all sides, forming a layer created by myelinated nerve fibers stretching in an ascending and descending direction. Bundles of nerve fibers formed by a set of nerve cell processes form pathways. There are three types of conductive bundles of the spinal cord: short ones, which determine the connection of brain segments at different levels, ascending (sensitive) and descending (motor). The formation of the spinal cord involves 31-33 pairs of nerves, divided into separate sections called segments. The number of segments is always similar to the number of pairs of nerves. The function of the segments is to innervate specific areas of the human body.

Functions of the spinal cord

The spinal cord is endowed with two important functions - reflex and conduction. The presence of the simplest motor reflexes (withdrawing a hand when burned, straightening the knee joint when hitting a tendon with a hammer, etc.) is due to the reflex function of the spinal cord. The connection between the spinal cord and skeletal muscles is possible thanks to the reflex arc, which is the path of nerve impulses. The conductor function is to transmit nerve impulses from the spinal cord to the brain using ascending pathways, as well as from the brain along descending pathways to the organs of various body systems.

The spinal cord of a person or animal is the most important part of the central nervous system. Through it, the brain communicates with muscles, skin, internal organs, and the autonomic nervous system. This ensures the vital functions of the human body, dog, cat or other mammal. The structure of the spinal cord is distinguished by its complex organization and narrow specialization of each area. Its biology is structured in such a way that any serious disorder manifests itself in problems with motor functions and somatic anomalies.

Externally, this organ is very similar to a cord stretched in a special canal of the spine. It has a right side and a left side. Its length does not exceed half a meter, and its diameter is about a centimeter.

We will consider in detail the structure of the spinal cord, the features of its organization, and the principles of operation. Knowing what the structure of the spinal cord is, you can easily understand how our movements are born, how the activity of neurons can manifest itself. We will also tell you what functions the spinal cord performs.

The spinal cord contains from 31 to 33 pairs of nerves, so it is divided into 31-32 segments. Each corresponds to a part of our body and continuously carries out its functions. The mass of such an important organ, without which not a single movement is possible, is only 35 grams.

Location area: spinal canal. At the top it immediately passes into the medulla oblongata, and at the bottom it is completed by the vertebrae of the coccyx.

Segmentation

The role of the spinal cord is to organize all human movements. To ensure maximum efficiency of its work, segments were identified during evolution, each of which ensures the functioning of a specific area of ​​the body.

This part of the nervous system begins to form already in the 4th week of embryonic development, but it will not be able to perform the main functions of the spinal cord immediately.

The sections of the spinal cord and their functions are now well studied. It is segmented into:

• cervical segments (8 pieces);
• chest (12 pieces);
• lumbar (5 pieces);
• sacral (5 pieces);
• coccygeal (from 1 to 3 pieces).

The human back ends with a small tailbone. It is a rudiment, that is, a part that has lost its significance in the course of evolution. This is actually the rest of the tail. Therefore, a person has very few coccygeal segments. He simply doesn't need the tail anymore.

What is it needed for

The spinal cord is the center that collects all information coming from the periphery. It then sends commands to the muscles and tissues, toning them. This is how all movements are born. This is complex and painstaking work, because a person makes hundreds of thousands of tiny movements per day. Its physiology is characterized by the complex organization and interaction of all parts of the central nervous system.

The spinal cord is reliably protected by three membranes at once:

• hard;
• soft;
• arachnoid.

Inside there is cerebrospinal fluid. The center of the brain is filled with gray matter. In cross-section, this area looks like a butterfly with its wings spread. Gray matter is a concentrate of neurons; they are the ones capable of transmitting a bioelectric signal.

Each segment consists of tens and even hundreds of thousands of neurons. They ensure full functioning of the musculoskeletal system.

There are three types of projections (horns) in the gray matter:

• front;
• rear;
• side.

Different types of neurons are distributed between the zones. This is a complex and well-organized system that has its own characteristics. There are a huge number of large motor neurons in the anterior horn area. Small intercalary neurons are located in the dorsal horns, and visceral (sensory and motor) neurons are located in the lateral horns.

It is the nerve fibers that form the pathways along which the signal is transmitted.

In total, scientists have counted more than thirteen million nerve fibers in the human spinal cord. The protective function for them is performed by the external vertebrae that form the spine. It is in them that the inner delicate and vulnerable spinal cord is located.

The gray matter is surrounded on all sides by many nerve fibers. The transmission of bioelectric signals occurs through the thinnest processes of neurons. Each person may have from one to many such processes. Neurons themselves are extremely small in size. Their diameter is no more than 0.1 mm, but the processes are striking in their length - it can reach one and a half meters.

There are different types of cells in gray matter. The anterior sections consist of motor cells and are very large. As the name itself suggests, they are responsible for motor functions. These are thin but very long fibers that go from the spinal cord directly to the muscles and set them in motion. Such fibers form large bundles and exit the spinal cord. These are the anterior roots. One of them goes out to the right, and the other goes out to the left.

In each section there are such sensitive fibers, from which a pair of roots are formed. Some sensory fibers connect to the brain. The second part is directed directly to the gray matter. The fibers end there. The end for them are different types of cells - motor, intermediate, intercalary. Through them, continuous regulation of movements and organs is carried out.

Organization of pathways

The pathways of the entire body are usually divided into:

• associative;
• afferent;
• efferent.

The task of associative pathways is to connect neurons between all segments. These connections are considered short.

Afferents provide sensitivity. These are ascending pathways that receive information from all receptors and send it to the brain. Efferent pathways transmit signals from the brain to neurons throughout the body. They belong to the descending paths.

Functions

The activity of the spinal cord is continuous. It provides motor activity of the body. There are two main functions of the human spinal cord - reflex and conduction.

Each department ensures the functioning of a completely specific area of ​​the body. Segments (cervical, thoracic, for example) provide the functions of the organs of the sternum and arms. The lumbar segment is responsible for the proper functioning of the muscles and digestive system. The sacral segment is responsible for the functions of the pelvic organs and legs.

Reflex

The reflex brain function is to organize reflexes. This allows the body, for example, to instantly respond to a signal of pain. The action of reflexes is striking in its efficiency. A person withdraws his hand from a hot object in a split second. During this time, information from the receptors to the brain and back has traveled a long way along the reflex arc.

When the sensitive nerve endings of the skin, muscle fibers, tendons, and joints receive irritation, this means that a nerve impulse has been sent to them. Such signals travel along the dorsal roots of nerve fibers and enter the spinal cord. Receiving a signal, motor and intercalary cells are excited. Then, along the motor fibers of the anterior roots, impulses are sent to the muscles. Having received such a signal, the muscle fibers contract. Simple reflexes occur through this mechanism.

A reflex is a reaction of the body in response to received irritation. All reflexes are provided by the work of the central nervous system. One of the functions of the spinal cord is reflex. It is provided by the so-called reflex arc. This is a complex path that nerve impulses travel from the peripheral components of the body to its spinal cord, and from there directly to the muscles. This is a difficult but vital process.

The simplest reflexes can save a person’s life and health. Retracting the hand that touched the hot item, we do not even suspect that the signal from the skin was transmitted with lightning speed along the nerve fibers to the brain, and then to the spinal cord. In response, an impulse was sent that contracted the muscles of the arm to avoid being burned. This is a clear manifestation of the reflex function.

Neurophysiologists have studied in detail almost all reflexes and the neural arches that ensure their implementation. These data allow for effective rehabilitation after injuries and a number of diseases, and also help in their diagnosis.

It is on this reflex that a diagnosis by a neurologist is based, in which the doctor lightly hits the patient’s patella tendon with a hammer. This is how the knee reflex is studied, by which one can judge the state of a certain part of the spinal cord.

However, the spinal cord is not an independent reflex system. Its functions are constantly controlled by the brain. They are closely connected by special bundles of nerve fibers. The fibers are very long, thin, and consist of white matter. Some signals are transmitted upward to the brain, and others - to the spinal cord.

The entire central nervous system is involved in the formation of coordinated complex movements. Each movement is a continuous flow of impulses from the brain to the spinal cord, and from it to the muscle fibers.

Conductor

This is the second important function. It consists in the fact that from the spinal cord nerve signals are transmitted higher to the brain. There, in the subcortical and cortical areas, all information is instantly processed, and appropriate signals are sent in response to it.

The conductor function works in those moments when we decide to take something, get up, go. This happens instantly, without wasting time on thinking.

This function is mostly provided by intermediate or interneurons. They send signals to motor neurons and also process information that comes from the skin and muscles. This is where peripheral signals and impulses from the brain meet.

The excitatory impulse is sent by insertion cells to different groups of motor cells. At the same time, the activity of other groups is inhibited. It is this complex process that ensures coherence and high coordination of human movements. This is how the refined movements of a pianist and ballerina appear.

Possible diseases

The human body has a unique section called the cauda equina. The spinal cord itself is missing, and only cerebrospinal fluid and bundles of nerves remain. If they are compressed, the body begins to experience pain, and disorders of the musculoskeletal system are observed. This disease is called “cauda equina” based on the location of the main cause.

If a horse's tail develops, a person may experience a number of symptoms. Lower back pain appears, muscles experience weakness, and the body begins to respond much more slowly to external stimuli. Inflammation may appear, and the temperature may even rise. If these alarming symptoms are ignored, the condition worsens. It becomes difficult for a person to move or sit for a long time.

The spinal cord is an important link in the nervous system, connecting organs and parts of the human body together, ensuring adequate interaction with the world. This complex biological mechanism organizes the implementation of vital functions, working in close connection with the head centers. Damage to any area of ​​the spinal cord will have serious health consequences.

Location, external structure

The spinal cord is located in the spinal canal, composed of the voids of the vertebrae. Its reliable protection and fixation is provided by a multilayer membrane (dural sac).

The location of the spinal cord is from the back of the head to the second vertebra of the lumbar sector. Externally, you can navigate where this organ is located in a person by looking at the top point of the first vertebra, as well as along the bottom edge of the ribs. The length of the spinal cord in males is 45 cm, in females it is from 42 to 43 cm.

The external structure of the spinal cord is a thick cord (cord) tapering downwards with two pronounced broadenings.

The general diagram of the structure of the spinal cord under the vertebrae looks like this (from the back of the head):

• medulla;
• pyramidal region;
• cervical thickening;
• lumbosacral widening;
• cone (area of ​​transition to thread);
• a thread that is attached to the coccyx, ending in the area of ​​the 2nd vertebra of the coccygeal region.

The interaction of the spinal centers with the head centers is ensured by the bridge, localized in the occipital region.

Shells, intershell spaces

How is the spinal cord structured? From the outside, it would be incomplete without a description of the surrounding dural sac, which copies the shape of the spine.

The membranes of the human spinal cord are three separate layers around the central canal: soft, arachnoid and hard. The hard shell of the spinal cord is formed by connective tissue made of strong fibers. Maintaining the spatial position is ensured by fixation to the edges of the intervertebral foramina; special cords (dorsal, lateral) connect the tissue to the surface of the periosteum of the spinal canal. The dura mater is separated from the media (arachnoid) by the subdural space.

The arachnoid membrane of the spinal cord is an intermediate layer of the dural sac. Here are the nerve roots, the brain itself, which is fenced off from the walls of the shell by a subarachnoid space filled with fluid (cerebrospinal fluid). The arachnoid layer is very dense, but thin. It is represented by cellular connective tissue.

The soft (choroidal) membrane is fused with the medulla. The fabric is woven with bundles of collagen fibers forming outer and inner circular layers. They contain a dense network of blood vessels.

A series of jagged plates are located along the soft shell. On the one hand, they are fused to the brain itself in the area between the posterior and anterior roots, on the other - to the arachnoid membrane, and through it - to the dura mater, acting as a kind of end-to-end fastener. Additional communication between the membranes and intershell spaces of the spinal cord is provided by the nerve roots.

The main functions of the spinal cord membranes are protective and trophic (regulation of blood flow).

The fluid in the intershell spaces protects nervous tissues from vibrations and shocks, and takes an active part in metabolic processes, removing metabolic products.

Functions

A person fulfills his physiological needs thanks to the unique structure and functions of the spinal cord, without thinking about what this organ is and what the principles of its operation are.

The main functions of the spinal cord include:

1. Reflex. Provides a muscle response to external irritation (tactile, thermal, acid, pain reflexes), movements of skeletal muscles, blood vessels, rectum, and genitourinary system.
2. Conductor. The human spinal cord is a translator of external signals to and from the head center. The conductor function of the spinal cord ensures the relationship between consciousness and reflexes.
3. The tonic function of the spinal cord maintains minimal muscle tension at rest (muscle tone).
4. Endocrine. The central spinal canal is lined with a special layer of cells - ependymoglia. In young people, they produce bioactive substances that regulate sexual function, blood pressure, and circadian rhythms.

What are the functions of the spinal cord (main ones) are briefly described in Table 1.

Table 1

Impaired functioning of nerve tissue is almost always associated with a person’s partial or complete loss of legal capacity.

Internal structure

The body of the brain, located in the spine, is composed of various types of nerve cells and fibers that form innervating muscles and organs, roots, as well as pathways for external and internal impulses.

Thickenings and grooves

The internal structure of the spinal cord consists of several sectors formed by longitudinally located depressions:

• anterior median fissure, running along the entire frontal part;
• median groove dividing the dorsal surface into 2 equal halves;
• on the sides of the anterior median fissure are the anterolateral grooves;
• on both sides of the dorsal median sulcus there are posterolateral ones.

As a result, the cord is divided into 2 halves (in the jumper there is the central spinal canal), each of which consists of 3 cord sections:

• between the dorsal median and posterolateral sulcus - the posterior cord;
• between posterolateral and anterolateral – lateral;
• between the anterior median fissure and the anterolateral groove - anterior.

Externally, the cords resemble long, voluminous ridges that make up the body of the cord.

Gray and white matter

The central canal (a remnant of the neural tube) is surrounded by the gray matter of the spinal cord, which in cross section looks like a butterfly (the letter “H”). The lower part is the anterior horns (wide, short, thick), the upper part is the posterior horns of the spinal cord (narrow, elongated). Along the canal in the area from the last cervical segment to the first lumbar segment, with anterior and posterior, lateral horns (pillars) stretch.

The gray matter consists of multipolar nerve cells (neurons) and fibers. Neurons consist of a body (soma, perikaryon), around which short branches (dendrites) grow, and a long process (axon). Dendrites catch impulses, transmit them to the body of the neuron, and from there the signal is transmitted to the tissue through axons.

Types of neurons:

• radicular. The processes of neurons extend beyond the membranes of the dural sac, reach muscle fibers, where they form synapses (the place of contact between neurons and cells receiving the signal);
• internal. Axons are located within the gray matter;
• fascicular. Their processes form pathways to the thickness of the white matter.

• sensitive (form lateral cords);
• vegetative (part of the anterior roots);
• associative (form internal segments);
• motor (directed to muscle fibers).

Diffusely scattered cells of the gray matter provide internal connections, some are grouped into the nuclei of the spinal cord.

On top, the gray matter is surrounded by white matter, which ensures the conduction of generated signals.

• short bundles connecting brain structures;
• afferent long (sensitive);
• efferent long (motor).

The connection between gray and white matter is provided by glia, a layer of cells that serves as a layer between neurons and capillaries.

Roots

The roots of the spinal nerves are formed by the axons of nerve cells. There are 2 types: front and rear. The anterior roots of the spinal cord grow in longitudinal rows from the anterior lateral sulcus. Composed of processes of motor neurons from the nuclei of the anterior and partially lateral horns of the gray matter. The posterior ones are formed from the processes of sensory neurons located in the spinal ganglia (in the intervertebral foramina). They enter through the posterior lateral sulcus. The anterior and posterior roots at the exit from the dural sac merge into the spinal nerve, forming a short trunk, which splits into 2 branches (receiving the signal and executing).

If the posterior (sensitive) roots are damaged, the ability to touch the areas attached to them is lost. If the anterior roots are crossed or compressed, then paralysis of the corresponding muscles occurs.

To date, it has been determined how many spinal nerve roots come from the spinal cord - 31 pairs.

Pathways

The spinal cord pathways provide internal intersectoral signal transmission and communication with the head center in both directions. The ascending tracts of the spinal cord are formed by thin and wedge-shaped bundles of afferent fibers located in the posterior and lateral cords (along the entire length of the cord). Excitation that occurs in the receptors of organs and skin as a reaction to external stimuli is transmitted by nerves to the dorsal roots and processed by neurons of the spinal nodes. From here the signal is sent to the head center or to the cells of the dorsal horns.

The descending tracts of the spinal cord are composed of bundles of efferent fibers of the anterior and lateral cords that go to the anterior horns of the gray matter. The fibers transmit the signal from the head center to the motor neurons of the spinal center, from where the information goes further to the recipient organ.

Thus, a reflex arc is formed, represented by three types of neurons:

• sensitive, perceiving an external signal and conducting it through their processes;
• intercalary, forming a synapse with the axon of sensitive cells, and transmitting a signal along their processes to the anterior horns;
• motor (in the anterior horns), which receive information from intercalary cells into their bodies and transmit it to muscle fibers along axons in the anterior roots.

There are several pathways along which nerve impulses travel. They are distributed among innervation zones (signal reception and transmission areas).

Segments: structure

The structure of the human spinal cord implies its division along its entire length into structural and functional units - segments:

• 8 cervical;
• 12 breast;
• 5 lumbar and sacral;
• 1 coccygeal.

The internal structure of the spinal cord is designed in such a way that each sector has its own area of ​​innervation, which is provided by four spinal roots, forming one nerve on each side of the segment.

The designation of the spinal cord segments and their functions is presented in Table 1.

Table 1

The sections of the spinal cord are displaced upward relative to the corresponding vertebral bones. The lumbar segments lag significantly behind, so the lower part of the spine is innervated by descending lashes of roots in the form of a horse's tail. The ratio of segments (neuromeres), parts of the body and spine (somites) is called skeletotopy.

Video

Video - structure of the spinal cord

Injuries and defeats

Damage to the spinal cord due to injury (bruise, compression, rupture (hemorrhage), concussion) or disease leads to serious consequences.

Chronic pathologies (myelopathy): General symptoms of spinal cord damage with complete mechanical transverse injury:

• below the level of destruction there are no voluntary motor reflexes, skin reflexes are also absent;
• no control over the pelvic organs (voluntary defecation and urination);
• violation of thermoregulation.

Specific signs of disease and brain damage depend on the location of the injury.

When the dural sac is compressed by a hernia or due to displacement of the vertebrae, as well as with the development of diseases, back pain occurs (usually in the neck, lower back). If the conical part is damaged, then pain impulses are localized in the lower section. There is weakness in the limbs, numbness in certain areas of the body, headaches, migraines, the urge to urgently urinate, and sexual dysfunction.

MRI, CT, and cerebrospinal fluid analysis (puncture) are used as diagnostic methods. The puncture procedure is performed under local anesthesia. A thin needle inserted into the intervertebral space under the control of an X-ray machine removes a small amount of fluid for examination.

Treatment of the spinal cord is as complex as its structure. Therefore, this area should be protected as much as possible from injury, using protective devices, preventing infectious lesions, and treating diseases in a timely manner (including acute respiratory viral infections, otitis media, sinusitis). The state of this part of the nervous system is largely determined by the integrity of the spinal structure

The human spinal cord is one of the organs of the central nervous system that performs regulatory functions. The structure of the spinal cord of the brain.

The human spinal cord is located in the spinal canal, where there is a cavity formed by all parts of the spine.

There is no clear boundary between the spinal cord and the brain; therefore, the upper level of the first cervical vertebra is taken as the approximate boundary.

In fact, the spinal cord is formed from white and gray matter, which are surrounded by three membranes: pia mater, arachnoid mater and dura mater. The cavities between them and the spinal canal are filled with cerebrospinal fluid.

The soft shell is represented by connective tissue, in the thickness of which there is a blood network that nourishes the soft tissues. The arachnoid membrane is separated from the soft membrane by a subarachnoid space filled with cerebrospinal fluid and blood vessels. The arachnoid membrane has growths or granulations that protrude into the venous circulatory network, and carries out the outflow of cerebrospinal fluid into the venous network. The dura mater, together with the periosteum, forms the epidural space, where adipose tissue and the circulatory network are located. Fusing with the periosteum of the intervertebral foramen, it forms a sheath for the spinal ganglia.

Human anatomy examines the structure of an organ above the intracellular level. The external is organized by segmentation type. Each segment is connected to the brain and peripheral nerves that innervate a specific area of ​​the human body.

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