What is the spinal cord. Brain and spinal cord

All vertebrates are spinal cord. It is a narrow elongated cord, the length of which is on average 50 cm. It plays the role of a channel connecting internal organs and the brain, and consists of several shells, between which are various kinds liquids.

Anatomical information

First of all, let's determine where the spinal cord is located and what is its structure. This body located in the cavity spinal canal, between the processes and cartilages of the ridge. It originates in the brain, namely on lower border large foramen magnum. The end point of this organ is between the 1st and 2nd lumbar vertebrae. In this place there is a transformation into a brain cone, which, in turn, is transformed into a terminal thread. It reaches the coccyx and forms a bundle of nerve connections there, which is called the "ponytail". The length of the spinal cord depends on the height of a person and can be either 40 centimeters or 50. Its weight also fluctuates - from 34 to 39 grams.

Constituent elements

Since the spinal cord is the second most important center of the nervous system, it consists mainly of neurons. The organ has three shells: soft, arachnoid and hard. In the center is the main channel that transports all impulses to the brain, and the space between it and the tissues is filled with cerebrospinal fluid. The hard outer shell is located in the epidural space, which is filled with a fatty layer and a venous network. It is worth adding that the organ has a structure that mimics the spine, that is, it looks like a long thin cord. For this reason, it was not difficult for our ancestors who worked in the field of anatomy to determine exactly where the spinal cord is located and to which other organs it is directly “connected”.

The main "working" elements

The functions that the spinal cord center possesses would be impossible without two substrates - white and gray. They are located directly in the channel of the brain itself, while the amount of one or another substance prevails on different areas. The bulk of the gray substrate is concentrated in the upper part of the tube and in lumbar. White matter predominates in the chest area, and the lower, the more its amount decreases and gradually reduces to zero. With a cross section of the spinal cord, we also see that the gray matter is the middle, which looks like the letter H, and it is surrounded on all sides by a white shell.

Features of gray matter

This substrate consists mainly of nerve fibers, cells and processes. Initially, it seems that the gray matter is the most central part brain, but in fact it performs the function of another, so to speak, shell. In the very center there is a very narrow cavity, which expands slightly only in the region of the cervical vertebrae (at this stage, the diameter is less than 1 mm). This cavity is the very channel through which the spinal cord transmits all the necessary information to the brain.

white matter characteristic

This substrate has much more complex structure, consists simultaneously of cells and tissues of different types, and is also characterized by an unstable thickness. The substance is based on myelinated and unmyelinated nerve fibers and neuroglia - supporting nervous tissue. All this is shrouded in cobwebs blood vessels between which connective tissue lies. Most of the neurons are bundled, which makes the substrate viscous and dense. Important components white matter are efferent and afferent passing paths to which associative fibers are attached. These elements ensure the connection of all parts of the spinal cord with each other.

How reflexes are formed

The main function of the spinal cord is reflex. Numerous nerve plexuses and channels adjoin the organ from all sides, which carry impulses from all components of our body. This system coordinating and directing involuntary movements that occur during sleep, sensations of pain, etc. The reflexes of all vertebrates are relatively identical and are divided into several types:

Flexion reflex - the name speaks for itself. To be more precise, this protective function body, allowing us to remove a damaging stimulus, for example, quickly pull our hand away from a hot one.
Proprioceptive is a reflex that prevents excessive stretching of muscle tissue.
Rhythmic and tonic functions are also the task of the spinal cord.
Animals and newborns have a primitive reflex - an extensor push. The bottom line is that when the heel is compressed, involuntary straightening occurs. knee joint. This function is considered primitive, and if a person, having matured, continues to respond to such a stimulus, then his spinal cord is damaged.

Connecting function

The tube that runs along the spine is called the brain for a reason. The structure of this organ is similar to the head center, in addition, they are directly related to each other. There is a whole web of neurons in the spinal cord, these fibers stretch to the most remote corners of our body and carry all the information about what is happening inside and outside of us. In addition, nerve cells are shrouded in vessels and capillaries, which form into special channels and go directly to the brain. As a result, it turns out that our spine, or rather what is in it, literally collects all the information about the work of the organs and transmits them to the main center.

It is worth remembering that any damage to the spinal cord is extremely dangerous. Losing at least one of its segments, you cut the “thread”, due to which your entire body functions.

When examining neurological patients, attention should be paid to the condition of the carotid and vertebral arteries. In this case, the leading role belongs to Doppler ultrasound (Fig. 4-14). The detected changes, if necessary, are confirmed by CT, MR or direct angiography.

Interventional radiology is the treatment of choice for intracranial aneurysms and other vascular malformations. For this purpose, the aneurysm cavity is embolized using a special embolization material (Fig. 4-15).

Rice. 4-13.CT angiography. Aneurysm of the right middle cerebral artery(arrow)

Rice. 4-14.duplex study carotid artery. On the left is a longitudinal section of the vessel, on the right is a transverse section. In the initial section of the internal carotid artery, a plaque is visible, causing a pronounced narrowing of the lumen of the vessel

4.5. INTRACRANIAL HEMORRHAGES

(HEMATOMS)

Intracerebral and meningeal hemorrhages (hematomas) may be manifestations of complications hypertension, atherosclerosis or malformation of the vessel. Hemorrhages may be accompanied by

Rice. 4-15.Angiography of the vertebrobasilar vessels of a patient with an aneurysm of the terminal basilar artery (indicated by an arrow). On the left is an angiogram before surgery, on the right - after aneurysm embolization with microcoils. Aneurysm is no longer visualized

lead to primary and secondary brain tumors. Hematomas are localized inside the brain (intracerebral) or between the membranes of the brain (subarachnoid, subdural, epidural).

By CT, hemorrhage is easily diagnosed immediately after its development. This is due to the high density gradient between the outflowing blood and the substance of the brain (Fig. 4-16). After some time, intracerebral hematoma is surrounded by a zone of cerebral edema with reduced density. Extensive hemorrhages can lead to a mass effect and break into the ventricles of the brain. Over time, the density of the hematoma decreases, and after 3-4 weeks it often becomes indistinguishable for CT. During the transition to a chronic state, atrophic and cystic changes develop at the site of the hematoma. The median structures and/or sulci and ventricles of the brain are usually displaced towards the lesion. Brain hematomas in all stages of development (especially in subacute and chronic) are clearly visible on MRI (Fig. 4-17).

Central nervous system- The brain and spinal cord are composed of gray and white matter.

Gray matter is a collection of bodies nerve cells, white matter is formed by the axons of nerve cells. Gray coloration is also characteristic of those parts of the nervous system that contain clusters of neuron bodies that have migrated far beyond the neural tube (sympathetic and other nodes).

In that part of the neural tube that forms the spinal cord, nerve cells are concentrated in the circumference of its cavity, forming Gray matter. The processes of these cells, located along the periphery of the tube wall, participate in the formation white matter. The cavity of the tube becomes narrower as the spinal cord develops and turns into central canal of the spinal cord filled with cerebrospinal fluid.

Two interceptions are visible in the anterior part of the neural tube, which divide it into three primary bladders: the anterior cerebral bladder, or forebrain , prosencephalon, midbrain oval bladder, or midbrain, mesencephalon, and the posterior cerebral bladder, or rhomboid brain, rhombencephalon.

Subsequently, five secondary bubbles are formed. forebrain divided into two vesicles: telencephalon, telencephalon and diencephalon, diencephalon.

The midbrain does not divide and becomes the third brain bubble. The rhomboid brain is divided into two vesicles: the hindbrain, metencephalon, and medulla oblongata myelencephalon.

At the same time, as a result of the uneven growth of the brain, a number of bends are formed: the parietal - at the level of the middle cerebral bladder, the bridge - in the region of the posterior cerebral bladder and the occipital -on the border transition of the spinal cord to the medulla oblongata.

Due to the significant thickening of the walls and the complication of the relief of the surface of the brain, the cavities of the cerebral vesicles take the form of cracks of various sizes and positions - ventricles of the brain.

The ventricles of the brain are filled with cerebrospinal fluid and communicate with each other and with the central canal of the spinal cord. The wall of each cerebral bladder develops into a certain part brain, and the cavity turns into the corresponding ventricle.

Ventral wall back section rhomboid brain is converted into medulla oblongata, and back wall remains a thin plate and forms lower brain sail.

Hind brain make up the cerebellum and pons. The cavity of the rhomboid brain turns into the fourth ventricle, which, through openings, communicates with the subarachnoid space. The dorsal wall of the midbrain forms the roof of the midbrain, or quadrigemina, and the ventral wall forms the legs of the brain.

The cavity of the midbrain turns into a narrow canal- brain plumbing, which connects the third and fourth ventricles.

The diencephalon is also intensively developing. The lateral walls of it form the thalamus, and the ventral wall - the hypothalamus.

The pineal body develops from the dorsal wall, but for the most part this wall remains undifferentiated and forms an epithelial plate. Cavity diencephalon turns into a narrow sagittally located gap between the thalamus -3 ventricle.

The telencephalon is represented by the right and left hemispheres big brain covering all other cerebral vesicles. The hemispheres consist of an externally located cerebral cortex (cloak), which makes up almost the entire mass of the hemispheres basal nuclei and occupying the most ventral position of the olfactory brain. Phollow telencephalon forms two lateral ventricles, of which the left is conditionally considered the first lateral ventricle.

The spinal and cerebral sections of the brain, which developed from the neural tube, together with the nerves extending from them, both anatomically and functionally represent a single whole. Nerves are a collection of processes of neurons. Dendrites of sensitive cells located in the nodes of the spinal cord and cranial nerves, terminate at the periphery with receptors. Receptors perceive stimuli from the external and internal environment, transforming them into nerve impulse. The latter is transmitted along the dendrites through the body of a sensitive neuron and then along its axon is transmitted to the spinal cord or brain.

The axons of cells located in the gray matter of the brain and spinal cord, as part of the nerves, are called motor fibers. They end at the periphery with effectors through which they transmit impulses from the brain and spinal cord to the executive organs.

The vast majority of nerves consist of afferent and efferent nerve fibers. Taking into account the predominant localization of the bodies of neurons in the brain and spinal cord and the special function of the brain and spinal cord, the entire unified nervous system is conditionally divided into central nervous system (CNS) brain and spinal cord and peripheral nervous system, which includes cranial and spinal nerves with a complex of nodes, as well as nerve plexuses.

according to functional - morphological features The nervous system is also divided into animal (somatic) and vegetative (autonomous) systems, and in the latter, sympathetic and parasympathetic are distinguished.

The spinal cord is formed from a cylindrical flattened tube with two thickenings. Its location is the canal of the spinal column.

The structure of the spinal cord

The length of the spinal cord with the central canal is 45 cm, and the diameter is 1 cm. It is located in cerebrospinal fluid, which provides homeostasis and nutrition, and also absorbs shocks and shocks.

At the top it goes on medulla oblongata, and the spinal cord ends with the first lumbar vertebrae.

The spinal cord is protected by three membranes. The arachnoid shell adjoins the outer hard, and the soft choroid close to the brain. The cavity between the pia mater and the arachnoid is filled with cerebrospinal fluid.

Gray matter, located on its cross section, occupies central part. It is surrounded by white matter that form nerve fibers. These processes of neurons are located along the spinal cord.

The gray matter looks like the letter H. The outgrowths that are facing forward are the anterior horns, and those that are facing back are called the back. Lateral horns are located in the thoracic region.

There are 31 segments in the spinal cord, each with a pair of anterior and posterior roots. Coming out of the spinal canal, they merge and form a mixed spinal nerve.

to the left and right sides 31 pairs of spinal nerves branch off from the body: 12 thoracic, 8 cervical, 5 sacral, 5 lumbar and 1 coccygeal. Also in the spinal cord is the lumbar and cervical thickening, which are formed by clusters of neurons.

Spinal Cord Functions

The spinal cord performs a reflex function - it provides the body with simple motor reactions. Also, his gray matter closes reflex arcs movement reflexes.

The functions of the spinal cord include the regulation of the skeletal muscles of the limbs and trunk. Functions sacral department associated with defecation, urination, and sexual reflexes, and thoracic region regulates the functioning of the respiratory system and the activity of the heart.

The spinal cord carries out conductive function . This is due to the fact that the impulses of the receptors enter it through the fibers of the posterior roots, and follow the ascending paths to the brain and departments that are higher.

And vice versa - from the departments of the central nervous system that lie above, the spinal cord receives command signals.

The connection between the spinal cord and the brain

Impulses coming from the brain and following along descending paths regulate the activity of the motor centers of the spinal cord. The brain controls the functioning of the spinal cord.

Pulses support muscle tone and form volitional and voluntary movements.

A person eats, breathes, moves and performs many other functions thanks to (CNS). It consists mainly of neurons (nerve cells) and their processes (axons), through which all signals pass. It should be noted glia, which is an auxiliary. Thanks to this tissue, neurons generate impulses going to the brain and spinal cord. It is these 2 organs that are the basis of the central nervous system and control all processes in the body.

The human spinal cord plays a special role and you can understand where it is located by looking at the cross section of the spine, since it is in it that it is located. Focusing on the structure of this organ, one can understand what it is responsible for and how the relationship with most human systems is carried out.

The spinal cord is composed primarily of arachnoid, as well as from soft and hard components. The fat layer located directly under the body protects the organ from damage. bone tissue in the epidural space.

Most people know where the spinal cord is located, but few understand its anatomical features. This organ can be represented as a thick (1 cm) wire, actually half a meter long, which is localized in the spine. The receptacle of the spinal cord is the spinal canal, consisting of vertebrae, due to which it is protected from external influences.

The organ starts from the occipital foramen, and ends at the level of the waist, where it is presented in the form of a cone, consisting of connective tissue. It resembles a thread in shape and goes straight to the coccyx (2 vertebrae). You can see the segments of the spinal cord in this picture:

The roots of the spinal nerves emerge from the canal, which serve to carry out the movements of the arms and legs. Above and in the center they have 2 thickenings at the level of the neck and lower back. In the lower part, the roots of the spinal cord resemble a tangle formed around the spinal filaments.

A cross section of the spinal cord looks like this:

The anatomy of the spinal cord is designed to answer many questions related to the work of this organ. Judging by the scheme, a furrow is localized behind the organ spinal nerve, and a special hole is located in front. It is through him that nerve roots that carry out the innervation of certain body systems.

The internal structure of the segment of the spinal cord tells many details of its work. The organ consists mainly of white (a set of axons) and gray (a set of bodies of neurons) matter. They are the beginning of many neural pathways and these segments of the spinal cord are primarily responsible for reflexes and signal transmission to the brain.

The functions of the spinal cord are diverse and depend on the level of which department the nerves are located. For example, from white matter go neural pathways anterior roots of the CNS. Rear end fibers are indicators of sensitivity. Of these, a segment of the spinal cord is formed, in which spinal roots at both sides. The main task of the white matter is the transmission of the received impulses to the brain for further processing.

The structure of the human spinal cord is not as complex as it seems. The main thing to remember is that the spine includes 31 segments. All of them differ in size and are divided into 5 departments. Each of them performs certain functions of the spinal cord.

white matter

The spinal canal is a collection of white matter. It consists of 3 cords surrounding, and consists mainly of axons covered with a myelin sheath. Thanks to myelin, the signal travels faster through them, and the substance gets its own shade.

White matter is responsible for the innervation of the lower extremities and the transmission of impulses to the brain. See his cords as well as horns gray matter you can in this picture:

Gray matter

Most people don't understand what gray matter looks like and why it's shaped like this, but it's actually quite simple. Due to the accumulation of nerve cells (motor and intercalary neurons) and in fact total absence it has axons grey colour. The gray matter is localized in the spinal canal and it seems to many that it is a butterfly because of the pillars and the plate in the center.

The gray matter is primarily responsible for motor reflexes.

A channel passes in its center, which is a receptacle for cerebrospinal fluid, which is. Its functions include damage protection and support. allowable pressure inside the cranium.

The main amount of gray matter falls on the anterior horns. They consist mainly of motor nerve cells that perform the function of innervation of muscle tissues at the level of this segment. A smaller amount of the substance goes to the posterior horns. They mainly include intercalary neurons, which serve to communicate with other nerve cells.

If you look at the spinal canal in section, then the intermediate zone is striking, localized in the space between the anterior and posterior horns. This area is located only at the level of the 8th vertebra cervical region and extends up to the 2nd lumbar segment. This area begins lateral horns, which are a collection of nerve cells.

The role of pathways

Pathways serve to connect the spinal cord and brain and originate in posterior funiculus white matter. They are divided into 2 types:

Ascending paths (transmitting a signal);
Descending paths (receiving a signal).

To have complete information about them anatomical features you need to look at this picture:

The signal is transmitted through certain beams, for example, upper part body in the spinal cord is the sphenoid plexus, and the lower thin. You can see next to what these fibers are located in this figure:

The cerebrospinal tract plays a special role in the conduction system. It starts from the skeletal muscles and ends directly in the cerebellum itself. Special attention should be paid to the thalamic pathway. It is responsible for the perception of pain and for the temperature of a person. The thalamus receives input from the anterior cerebellar tract, which is composed primarily of interneurons.

Functions

A person has always had many questions regarding his body, because it is difficult to understand how all systems are interconnected. In the spinal cord, the structure and functions are interconnected, therefore, for any pathological changes arise horrible consequences. It is virtually impossible to eliminate them, so you need to take care of your spine.

The spinal cord is responsible for the following functions:

Conductor. Its essence lies in the transmission of a signal certain parts organism depending on the localization of the nerve bundle. If the matter concerns upper half body, then responsible for it cervical region, for the lumbar organs, and the sacral innervates the pelvis and lower limbs.
Reflex. Such a function is performed without the participation of the brain, for example, if you touch a hot iron, the limb moves involuntarily.

Fixed spinal cord

Many are associated with the spinal cord. various pathologies whose treatment is carried out mainly in a hospital setting. Such diseases include the fixed spinal cord syndrome. This pathological process is diagnosed extremely rarely and the disease is characteristic of both children and adults. The pathology is characterized by fixation of the spinal cord to spinal column. Most often, the problem occurs in the lumbar region.

A fixed spinal cord is usually found in diagnostic center by using instrumental methods examination (MRI), and it occurs due to such reasons:

Neoplasms that compress the spinal cord;
Emerging scar tissue after surgery;
Severe injury in the lumbar region;
Vice Chiari.

Typically, fixed spinal cord syndrome in patients manifests itself in the form neurological symptoms and the main manifestations concern the legs and the area of damage. A person's lower limbs are deformed, it becomes difficult to walk and there are malfunctions in the work of the pelvic organs.

The disease occurs at any age and its course of treatment usually consists of surgery and long period recovery. Basically, after surgery, it is possible to eliminate the defect and partially save the patient from the consequences of the pathology. Because of what people begin to actually walk freely and cease to experience pain.

There is another pathology that some experts associate with the spinal cord, namely hemispasm (hemifacial spasm). It is a breach facial nerve as a result, there are contractions of the muscle tissue located on the face. The disease proceeds without pain and such spasms are called clonic. They occur due to compression. nervous tissue in the region of its exit from the brain. Diagnostics pathological process performed using MRI and electromyography. According to statistics compiled every year, hemifacial spasm can be diagnosed in 1 out of 120,000 people and the female gender suffers from it 2 times more often.

Basically, compression of the facial nerve occurs due to vessels or neoplasms, but sometimes hemispasm occurs due to such reasons:

Demyelination process;
Spikes;
Bone anomalies;
Tumors located in the brain.

Hemifacial spasm can be managed with medication. For the treatment of the facial nerve, Baclofen, Levatracem, Gabapentin, Carbamazepine, etc. are used. They will have to be taken enough for a long time, so this course has its drawbacks:

Over time, the effect of drugs begins to end faster and to treat the facial nerve, you will have to change drugs or increase the dosage;
Many of these drugs have a sedative effect, so people diagnosed with hemispasm are often drowsy.

Despite the disadvantages, many cases have been recorded complete cure facial nerve and removal of hemispasm. Worked especially well drug therapy on the early stages development of pathology.

Hemifacial spasm can also be eliminated with an injection of botulinum toxin. It effectively eliminates the problem at any stage. Of the minuses of the procedure can be noted high cost and contraindications, which include allergic reactions on the composition of the drug and eye diseases.

most efficient and fast treatment hemispasm is surgical intervention. It is carried out in order to eliminate compression, and in the case of a successful operation, the patient is discharged after a week. Achieved full effect recovery is fast enough, but in some cases stretches up to six months.

The spinal cord is an important center of the nervous system and any deviations in its structure can affect the entire body. That is why, with the manifestation of neurological symptoms, you should contact a neurologist for examination and diagnosis.