The cerebellum lies in the posterior cranial fossa, covered from above by a process of the dura mater - the cerebellar integument, which separates it from the occipital lobes hanging from above (Fig. 3).

In the cerebellum, two hemispheres are distinguished, connected by an unpaired lobule-worm, and three pairs of legs: upper middle, lower ().

The horizontal fissure, running along the posterior edge of the cerebellum, serves as the boundary between the upper and lower surfaces of the hemispheres. On the lower surface there is a recess - a valley, with which the cerebellum is adjacent to the trunk. The entire surface of the cerebellum is indented with deep grooves - cracks, between which there are gyrus-leaves. Groups of convolutions, separated by deeper grooves, form the lobules of the cerebellum.

The furrows run across the cerebellum without interruption through the hemispheres and the worm, so each lobule of the worm corresponds to two (left and right) lobes of the hemispheres. The lobules are combined into 3 lobes of the cerebellum: anterior, posterior and flocculent-nodular. CEREBELLAR CORK (). Due to deep furrows, the area of ​​​​the cerebellar cortex is about 850 square meters. cm and has three layers: inner-granular, middle - ganglionic, outer - molecular.

The granular layer consists of a large number of granule cells (about 100 billion), their axons rise to the outer layer of the cerebellar cortex, branch in a T-shape into two fibers that run parallel to the surface and enter into numerous synaptic contacts. Between the granule cells are interneurons - Golgi cells.

In the ganglion layer (with the exception of shreds) there are the largest pear-shaped nerve cells - Purkinje cells, a powerful branched dendritic tree of which rises into the outer layer of the cerebellar cortex, and the axons of Purkinje cells go deep into the nuclei of the cerebellum. Thus, the molecular layer of the cortex is represented by an accumulation of T-shaped branches, dendrites of Purkinje cells in contact with them, and interneurons scattered between the fibers: stellate and basket cells.

Rice. 12. Cerebellum: A - top view, B - bottom view

1. hemisphere
2. worm
3. horizontal fissure of the cerebellar peduncle
4. primary gap
5. secondary gap
6. posterior lateral fissure
7. valley
8. superior cerebellar peduncles
9. middle cerebellar peduncles
10. inferior cerebellar peduncle

WORMS AND HEMISPHERES

Lobes of the cerebellum	Worm segments	Lobes of the hemispheres
Front	11. uvula of the cerebellum	12. ligamentous gyrus
	13. central	14. wings of the central lobule
	15. top of the hill	16. anterior quadrangular
rear	17. stingray	18. back quadrangular
	19. leaf	20. superior lunate
	21. tubercle	22. inferior lunate
	23. pyramid	24. thin, digastric (D)
		26. tonsil
Klochkovo-nodular	25. sleeve	28. shred, leg, okolochok
	27. knot

Rice. 13. Scheme of the structure of the cerebellar cortex

1. molecular layer
2. ganglion layer
3. granular layer
4. white matter
5. Purkinje cells
6. dendrites class Purkinje
7. axons of the Purkinje class
8. golgi cells
9. stellate cells
10. mossy fibers
11. liana fibers

Fig.14. Cerebellar nuclei
(on the front section)

A. Diencephalon
B. Midbrain
C. Cerebellum

12. worm
13. hemisphere
14. furrows
15. bark
16. white matter
17. upper legs
18. core tent
19. spherical nuclei
20. cork kernels
21. jagged nuclei

Afferents enter the cerebellar cortex through bryophyte (mossy) and climbing (liana-shaped) fibers. Mossy fibers braid granular cells and carry information from the vestibular system, the cerebral cortex, the spinal cord and the reticular formation.

RF projections are diffuse i.e. they enter all layers of the cortex, including HA - ergic fibers from the blue spot and serotonergic fibers from the raphe nuclei. Climbing fibers go from the lower olives to the outer layer of the cortex on the dendritic tree of Purkinje cells.

Faculty of Biology and Chemistry, UdGU, 2004, Bolycheva E.V.

The cerebellum is involved in almost all movements, it helps a person to throw a ball or walk around the room. Cerebellar problems are rare and are mainly associated with impaired movement and coordination.

Anatomy of the brain

(c) Shutterstock

The brain consists of four lobes, each lobe has its own function.

The frontal lobe is located in the front and top of the brain. It is responsible for high levels of human thinking and behavior such as planning, judgment, decision making, control, and attention.

The parietal lobe is located at the top of the brain, behind the frontal lobe. It is responsible for receiving sensory information. The parietal lobe of the brain is responsible for understanding someone's position in their environment.

The temporal lobe is located in the lower anterior part of the brain. It is associated with visual memory, language and emotions.

And finally, the occipital lobe is located at the back of the brain and processes what a person sees.

Along with the lobes, the brain includes the cerebellum and the brain stem.

The brain stem controls vital functions such as breathing, circulation, sleep, digestion, and swallowing. These involuntary functions are under the control of the autonomic nervous system. The brain stem also controls reflexes.

The cerebellum is located in the lower back of the brain, behind the brainstem.

Cerebellar functions:

Movement coordination. Most body movements require the coordination of several muscle groups. The cerebellum allows the body to move smoothly.

Maintaining a balance. The cerebellum detects changes in the balance of movement. It sends signals to the body to adjust to movement.

Eye movement coordination.

The cerebellum helps the body learn movements that require practice and fine tuning. For example, the cerebellum plays a role in learning the movements required to ride a bicycle.

Researchers believe that the cerebellum influences thinking and is associated with language and mood, but these functions are not well understood.

Symptoms of damage to the cerebellum

The most common sign of a cerebellar disorder is impaired muscle control. This is because the cerebellum is responsible for controlling balance and voluntary movements.

Symptoms and signs of a cerebellar disorder include:

Lack of muscle control and coordination;

Difficulty walking;

Difficulties with speech;

Pathological eye movements;

Headaches.

Cerebellar ataxia

Change in gait in a woman with cerebellar disease

ICD-10:

G11.1 Early cerebellar ataxia

G11.2 Late cerebellar ataxia

G11.3 Cerebellar ataxia with impaired DNA repair

Ataxia is a disorder of the cerebellum.Ataxiais a loss of muscle coordination and control due to a problem with the cerebellum. It can be caused by a virus or a brain tumor. Loss of coordination is often the initial sign of ataxia. Other symptoms include blurry vision, difficulty swallowing, fatigue, difficulty with precise muscle control, and changes in mood and thinking.

There are several diseases that cause symptoms of ataxia. These are heredity, poisons, stroke, tumors, head injuries, multiple sclerosis, cerebral palsy, viral infections.

Genetic or hereditary ataxia is caused by a genetic mutation. There are several different mutations and types of hereditary ataxia. These disorders are rare, the most common type being Friedreich's ataxia, which affects up to 1 in 50,000 people. Symptoms of Friedreich's ataxia usually appear already in childhood.

Idiopathic (sporadic) ataxia is a group of degenerative movement disorders with no evidence of inheritance. Impaired coordination and speech are the first symptoms. Idiopathic ataxia usually progresses slowly and may be accompanied by syncope, abnormal heart contractions, erectile dysfunction, and loss of bladder control.

So far, there is no specific treatment to alleviate or eliminate the symptoms of the disease, except in cases of ataxia, where the cause is a lack of vitamin E.

There is ataxia caused by toxins. Poisons damage the nerve cells of the brain - the cerebellum, which leads to ataxia.

Toxins that cause cerebellar ataxia:

Alcohol;

Medications, especially barbiturates and benzodiazepines;

Heavy metals such as mercury and lead;

Paint solvents.

Treatment and recovery depends on the toxin that caused the brain damage.

Viral ataxia. This disorder is called acute cerebellar ataxia and most often affects children. Ataxia is a rare complication of chickenpox.

Acute cerebellar ataxia can also be caused by Coxsackie virus, Epstein-Barr virus and HIV. Lyme disease, caused by bacteria, is also associated with these conditions.

Ataxia usually disappears a few months after the disappearance of the viral infection.

Strokecan affect any area of ​​the brain. The cerebellum is a less common site for stroke. A blood clot or hemorrhage in the cerebellum can cause ataxia, resulting in headache, dizziness, nausea, and vomiting. Stroke treatment can reduce the symptoms of ataxia.

brain tumorsare benign when they do not spread throughout the body, and malignant when tumors metastasize.

Symptoms of a tumor in the cerebellum include:

Headache;

Vomiting without nausea;

Difficulty walking;

Diagnosis and treatment will vary depending on age, health status, course of the disease, and other factors.

To avoid damage to the cerebellum, the overall health of the brain must be maintained. Reducing the risk of stroke, brain injury, and exposure to poisons can help prevent some forms of ataxia.

Used Books:

1. De Smet, Hyo Jung, et al. " The cerebellum: its role in language and related cognitive and affective functions» Brain and language 127.3 (2013): 334-342.
2. Lippard, Jim. " The Skeptics Society & Skeptic magazine.»

Did you like the news? Follow us on Facebook

The cerebellum of the human brain is one of the structures of the central nervous system responsible for the coordination of movements, the state of muscle tone and balance control. This structure is located behind the bridge of Varolia and the medulla oblongata.

In the early studies, the cerebellum was not assigned specific functions. The first researchers believed that this structure is a small copy of the telencephalon, and it is responsible for memory function. However, in later centuries, through surgical removal procedures, scientists concluded that the “small brain” is responsible for some balance mechanisms. At the end of the 19th century, Luciani managed to study some diseases of this department, such as ataxia or muscle atony. In the modern world of science, the cerebellum is actively studied in the course of many experiments confirming its role in shaping the motor control of the departments of the human body.

Structure

Like the telencephalon, the cerebellar hemispheres have a cortex. The structure itself consists of white and . represented by the body of the cerebellum itself. Two lobes of a small brain are interconnected by a worm. The mass of the cerebellum reaches an average of 130 g, and the diameter is up to 10 cm. The occipital cortex of the telencephalon rises directly above the cerebellum.

The cerebellum of the human brain is separated from the cerebrum by a deep fissure. A small process of the dura mater of the telencephalon is wedged into it. This outgrowth, called the cerebellum, stretches over the region of the posterior cranial fossa.

Functional links

The cerebellum performs its functions due to its connections with neighboring brain structures. Located between the cortex of the two hemispheres and the spinal cord, the cerebellum receives a copy of the sensitive information coming from the spinal cord to the brain. This structure also receives efferent information from the motor centers. The cerebral cortex of the telencephalon supplies data on the current state of the position of body parts in space, and the spinal cord requires this data. Thus, the cerebellar cortex acts as a filter, comparing the first and second types of information.

Functions of the cerebellum

Despite the fact that the cerebellar cortex is almost directly connected with the cerebral cortex, the functions of the cerebellum of the human brain are not controlled by consciousness.

In all living creatures that have a spine, the cerebellum performs similar functions, which include the following:

• Movement coordination.
• muscle memory.
• Management of muscle tone.
• Regulation of body position in space.

All functions are confirmed by experiments. Removing or violating the structure of the cerebellum, a person has various kinds of disorders of coordination, regulation of movements and retention of posture. Since the cerebellum is not subject to human consciousness, its functions are carried out reflexively.

Anatomically and physiologically, the cerebellum is connected with other parts of the nervous system by a variety of connections, among which there are afferent and efferent fibers. The latter pass through the upper legs of the structure. As you can see, the middle legs connect the cerebellum and some parts of the cerebral cortex directly.

Consequences of disruption

One way or another, the cerebellum, like any structure of the nervous system, is able to succumb to various diseases and conditions, including infectious diseases, traumatic brain injuries or tumors. People who have experienced various diseases subsequently ask themselves the question of how train the cerebellum.

The development of the functions of the cerebellum can be achieved by performing a number of simple exercises, including:

• Performing 15 tilts in a position where the feet are adjacent to each other with eyes closed.
• Raising and lowering the leg with flexion of the knee joint with eyes closed. It is necessary to repeat up to 20 times.

A static position where one foot is placed in front of the other. To do this, close your eyes and stand for 20-30 seconds. The key to how to develop the cerebellum lies in the performance of these actions, which are imprinted in the brain and, after a short course of repetitions, are fixed as reflexes. These exercises should be performed systematically for a month.

Diseases

Lesions of the cerebellum are reflected in the form of motor disorders, impaired coordination, speech disorders and impaired muscle tone.

Abscess of the cerebellum, otogenic- This is a serious disease characterized by the presence of pathological cavities in the structure of the organ, which are filled with pus. The disease begins with inflammation in the ear. In the future, inflammation, along the way of the middle and inner ear, penetrates into the cranial cavity and spreads to the cerebellum.

Among the symptoms, there is a sharp increase in temperature, an increase in intracranial pressure and the development of some focal signs. The neurological clinic manifests itself in the form of the following symptoms:

• Gait disorders.
• Disorders of conscious movements.
• Loss of coordination of the whole body or its individual parts.

Agenesia of the cerebellar vermis- This is a pathology that is caused by the congenital absence of the connecting structure of the lobes of the cerebellum - the worm. Among the reasons are:

• chronic smoking of the mother during gestation;
• the use of alcoholic beverages, drugs or toxic substances in the same period;
• exposure;
• maternally transmitted acute infections.

A baby born without a worm has the following symptoms:

• Inhibition in the development of motor functions.
• Impaired coordination in the work of bodily muscles.
• Scanned speech.
• Difficulty maintaining balance both while sitting and standing.
• Violation of the uniformity of gait.

In addition, congenital cerebellar agenesis may be in the Dandy-Walker syndrome complex. This pathology is characterized, in addition to the absence of a worm, by cystic formations in the fourth ventricle and an increase in the volume of the posterior cranial fossa.

The cerebellum is located in the posterior cranial fossa above the medulla oblongata and the pons.

It consists of a worm and two hemispheres. The white matter contains its own nuclei of the cerebellum - dentate, corky, spherical, tent. The cerebellum is connected with other parts of the central nervous system by three pairs of legs.

Afferent impulses to the cerebellum come through somatosensory pathways, including the Flexig and Gowers bundles, from the nuclei of Gol and Burdakh, along the vestibulocerebellar pathways, the olivocerebellar pathways and from the cerebral cortex, mainly along the frontal pontine pathway and the occipitotemporal pontine pathway.

The efferent connections of the cerebellum are carried out with the supraspinal motor centers through their own nuclei, and the latter through the segmental motor apparatus. The tent nucleus sends impulses to the vestibular nuclei (Deiters' nucleus) and the reticular formation, the spherical and corky nuclei send information to the red nucleus, and the dentate nucleus sends information to the red nucleus and thalamus.

The cerebellar cortex has three layers: molecular, ganglionic and granular. Afferent impulses enter the cerebellar cortex through two types of fibers: mossy (bryophyte) and liana-shaped. Excitatory impulses are sent along mossy fibers from nuclei to granule cells, and from them Golgi cells, stellate cells and basket cells are excited along parallel fibers. Afferent impulses from the somatosensory pathways, vestibular and cortical pathways travel along the liana-like fibers and excite Purkinje cells. Golgi cells inhibit efferent corn cells, and stellate and basket cells inhibit Purkinje cells. The main efferent Purkinje cells, when excited, always inhibit their own nuclei of the cerebellum. Thus, any excitation that comes to the cerebellar cortex turns into a whole series of inhibitory impulses that are important for coordinating the work of the segmental apparatus.

Layers of the cerebellar cortex:

1. Molecular (external)
2. Ganglionic (layer of Purkinje cells).
3. Granular (cell layer of grains)

Cerebellar connections:

Inferior cerebellar peduncles:

to the RF of the medulla oblongata - the cerebellar-reticular path,

to the olive of the medulla oblongata - cerebellar-olive,

from the vestibular nuclei - the vestibulo-cerebellar pathway,

from proprioceptors - the posterior spinal cerebellar pathway Flexig,

from the nuclei of Gaulle and Burdakh - bulbar-cerebellar,

from the nuclei of FMN - nuclear-cerebellar,

from the olive of the medulla oblongata - olive-cerebellar

Middle peduncles of the cerebellum:

from the own nuclei of the bridge - the cortical-bridge-cerebellar path (the own nuclei of the bridge also receive collaterals from the pyramidal path)

superior cerebellar peduncle:

to the RF of the midbrain - cerebellar-reticular,

to the red nucleus of the midbrain - cerebellar-dentate-red nuclear path

to the central nuclei of the thalamus - the cerebellar-dentate-thalamic path.

from proprioreceptors - anterior spinal-cerebellar path of Gowers

CONNECTIONS OF THE CEREBELLAR CORTEX

1. Afferent connections
   • MOSHY FIBERS: from
     • Vestibular nuclei - vestibulocerebellar tracts
     • Spinal cord - spinocerebellar tracts
     • Reticular formation - reticulocerebellar tracts
     • The cerebral cortex - corticocerebellar tracts
   • LIANOID FIBERS: from the lower olive - Purkinje cells (1 fiber-1 cell)
2. Efferent connections- to the subcortical nuclei

CONNECTIONS OF THE NUCLEI OF THE CEREbellum

1. Afferent connections of all nuclei- from the cerebellar cortex:

• JENTATED NUCLEI: from the lateral zones of the cerebellar cortex
• INTERMEDIATE NUCLEI (CORK AND GLOBULAR): from the middle part of the cerebellar cortex
• CORE OF THE TENT: from the medial part of the cortex (worm)

1. Efferent connections of nuclei:

• JENTATED NUCLEI: to the motor nuclei of the thalamus and then to the motor cortex of the cerebral hemispheres
• INTERMEDIATE NUCLEI: to the red nuclei, part - to the thalamus
• CORE OF THE TENT: to the reticular formation, vestibular nuclei, part - to the red nucleus

Functions of the cerebellum:

1. Regulation of muscle tone, posture and balance
2. Coordination of posture and performed purposeful movement, synergy of slow and fast movements, including those with the participation of the cerebral cortex
3. Programming of purposeful movements.
4. Movement initiation: activity of neurons of the cerebellum (dentate nucleus) precedes the onset of movement by 0.1-0.3 s
5. Influence on the autonomic functions of the body

Symptoms of cerebellar damage: Static, statokinetic reflexes are disturbed:

1. Ataxia - a violation of coordination of movement, a disorder of strength, size, speed and direction of movement (Dysmetria - insufficiency or redundancy of movements.)
2. Adiadochokinesis is a violation of the correct alternation of opposing movements (for example, pronation and supination of the hand).
3. Asynergy - the inability to simultaneously include synergistic muscles in the work, a violation of their friendly reactions.
4. Dystonia - lack of tone of some muscles, with a predominance of the tone of another muscle group.
5. Astasia - muscles lose their ability to fused tetanic contraction. As a result, the head, trunk and limbs constantly tremble and sway, especially when performing voluntary movements.
6. Intention tremor is a tremor that is absent when at rest and manifests itself when moving.
7. Abasia - a violation of gait: gait "drunk") - shaky, with legs wide apart and sweeping movements.
8. Asthenia - increased fatigue, since movements are not economical, with the participation of a large number of muscles.
9. Nystagmus - twitching of the eyeballs (horizontal, vertical, rotational).
10. Dysarthria can take one of two forms: slow or slurred speech (as in pseudobulbar palsy) or "scanned speech" in which words are fragmented into syllables, each of which may be pronounced with more or less force than normal.

The cerebellum is a part of the vertebrate brain responsible for coordination of movements, regulation of balance and muscle tone. In humans, it is located behind the medulla oblongata and the pons, under the occipital lobes of the cerebral hemispheres. Through three pairs of legs, the cerebellum receives information from the cerebral cortex, the basal ganglia of the extrapyramidal system, the brain stem and spinal cord. Relationships with other parts of the brain may vary in different taxa of vertebrates.

In vertebrates with cerebral cortex, the cerebellum is a functional offshoot of the main cortex-spinal cord axis. The cerebellum receives a copy of the afferent information transmitted from the spinal cord to the cerebral cortex, as well as efferent information from the motor centers of the cerebral cortex to the spinal cord. The first signals the current state of the controlled variable, while the second gives an idea of ​​the required final state. By comparing the first and second, the cerebellar cortex can calculate the error, which is reported to the motor centers. So the cerebellum continuously corrects both voluntary and automatic movements.

Although the cerebellum is connected to the cerebral cortex, its activity is not controlled by consciousness..

Cerebellum - Comparative anatomy and evolution

The cerebellum phylogenetically developed in multicellular organisms due to the improvement of voluntary movements and the complication of the body control structure. The interaction of the cerebellum with other parts of the central nervous system allows this part of the brain to provide accurate and coordinated body movements in various external conditions.

In different groups of animals, the cerebellum varies greatly in size and shape. The degree of its development correlates with the degree of complexity of body movements.

The cerebellum is present in representatives of all classes of vertebrates, including cyclostomes, in which it has the form of a transverse plate that spreads over the anterior part of the rhomboid fossa.

The functions of the cerebellum are similar in all classes of vertebrates, including fish, reptiles, birds, and mammals. Even cephalopods have a similar brain formation.

There are significant differences in shape and size in different biological species. For example, the cerebellum of lower vertebrates is connected to the hindbrain by a continuous plate in which fiber bundles are not anatomically distinguished. In mammals, these bundles form three pairs of structures called the cerebellar peduncles. Through the legs of the cerebellum, the connections of the cerebellum with other parts of the central nervous system are carried out.

Cyclostomes and fish

The cerebellum has the largest range of variability among the sensorimotor centers of the brain. It is located at the anterior edge of the hindbrain and can reach enormous sizes, covering the entire brain. Its development depends on several factors. The most obvious is associated with pelagic lifestyle, predation or the ability to swim efficiently in the water column. The cerebellum reaches its greatest development in pelagic sharks. Real furrows and convolutions are formed in it, which are absent in most bony fish. In this case, the development of the cerebellum is caused by the complex movement of sharks in the three-dimensional environment of the world's oceans. The requirements for spatial orientation are too great for it not to affect the neuromorphological provision of the vestibular apparatus and the sensorimotor system. This conclusion is confirmed by the study of the brain of sharks that live near the bottom. The nurse shark does not have a developed cerebellum, and the cavity of the IV ventricle is completely open. Its habitat and way of life does not impose such stringent requirements on spatial orientation as those of the long-winged shark. The result was a relatively modest size of the cerebellum.

The internal structure of the cerebellum in fish differs from that of humans. The cerebellum of fish does not contain deep nuclei, there are no Purkinje cells.

The size and shape of the cerebellum in primary aquatic vertebrates can change not only in connection with a pelagic or relatively sedentary lifestyle. Since the cerebellum is the center of somatic sensitivity analysis, it takes an active part in the processing of electroreceptor signals. Very many primary aquatic vertebrates possess electroreception. In all fish with electroreception, the cerebellum is extremely well developed. If the electroreception of one's own electromagnetic field or external electromagnetic fields becomes the main afferent system, then the cerebellum begins to play the role of a sensory and motor center. Their cerebellum is often so large that it covers the entire brain from the dorsal surface.

Many vertebrate species have areas of the brain that are similar to the cerebellum in terms of cellular cytoarchitectonics and neurochemistry. Most fish and amphibian species have a lateral line organ that senses changes in water pressure. The part of the brain that receives information from this organ, the so-called octavolateral nucleus, has a structure similar to the cerebellum.

Amphibians and reptiles

In amphibians, the cerebellum is very poorly developed and consists of a narrow transverse plate above the rhomboid fossa. In reptiles, an increase in the size of the cerebellum is noted, which has an evolutionary justification. A suitable environment for the formation of the nervous system in reptiles could be giant coal blockages, consisting mainly of club mosses, horsetails and ferns. In such multi-meter blockages from rotten or hollow tree trunks, ideal conditions could have developed for the evolution of reptiles. Modern deposits of coal directly indicate that such blockages from tree trunks were very widespread and could become a large-scale transitional environment for amphibians to reptiles. In order to take advantage of the biological benefits of tree blockages, it was necessary to acquire several specific qualities. First, it was necessary to learn how to navigate well in a three-dimensional environment. For amphibians, this is not an easy task, since their cerebellum is very small. Even specialized tree frogs, which are a dead-end evolutionary branch, have a much smaller cerebellum than reptiles. In reptiles, neuronal interconnections are formed between the cerebellum and the cerebral cortex.

The cerebellum in snakes and lizards, as well as in amphibians, is located in the form of a narrow vertical plate above the anterior edge of the rhomboid fossa; in turtles and crocodiles it is much wider. At the same time, in crocodiles, its middle part differs in size and bulge.

Birds

The cerebellum of birds consists of a larger middle part and two small lateral appendages. It completely covers the rhomboid fossa. The middle part of the cerebellum is divided by transverse grooves into numerous leaflets. The ratio of the mass of the cerebellum to the mass of the entire brain is the highest in birds. This is due to the need for fast and accurate coordination of movements in flight.

In birds, the cerebellum consists of a massive middle part, usually crossed by 9 convolutions, and two small lobes, which are homologous to a piece of the cerebellum of mammals, including humans. Birds are characterized by a high perfection of the vestibular apparatus and the system of coordination of movements. The result of the intensive development of the coordination sensorimotor centers was the appearance of a large cerebellum with real folds - furrows and convolutions. The avian cerebellum was the first vertebrate brain structure to have a cortex and a folded structure. Complex movements in a three-dimensional environment became the reason for the development of the cerebellum of birds as a sensorimotor center for coordinating movements.

mammals

A distinctive feature of the mammalian cerebellum is the enlargement of the lateral parts of the cerebellum, which mainly interact with the cerebral cortex. In the context of evolution, the enlargement of the lateral parts of the cerebellum occurs together with the enlargement of the frontal lobes of the cerebral cortex.

In mammals, the cerebellum consists of a vermis and paired hemispheres. Mammals are also characterized by an increase in the surface area of ​​the cerebellum due to the formation of furrows and folds.

In monotremes, as in birds, the middle section of the cerebellum predominates over the lateral ones, which are located in the form of insignificant appendages. In marsupials, edentulous, bats and rodents, the middle section is not inferior to the lateral ones. Only in carnivores and ungulates do the lateral parts become larger than the middle section, forming the cerebellar hemispheres. In primates, the middle section, in comparison with the hemispheres, is already very undeveloped.

The predecessors of man and lat. Homo sapiens of the Pleistocene time, the increase in the frontal lobes occurred at a faster rate compared to the cerebellum.

Cerebellum - Human Cerebellum Anatomy

A feature of the human cerebellum is that it, like the brain, consists of the right and left hemispheres and the unpaired structure connecting them - the "worm". The cerebellum occupies almost the entire posterior cranial fossa. The diameter of the cerebellum is much larger than its anteroposterior size.

The mass of the cerebellum in an adult ranges from 120 to 160 g. By the time of birth, the cerebellum is less developed than the cerebral hemispheres, but in the first year of life it develops faster than other parts of the brain. A pronounced increase in the cerebellum is noted between the 5th and 11th months of life, when the child learns to sit and walk. The mass of the cerebellum of a newborn is about 20 g, at 3 months it doubles, at 5 months it increases 3 times, at the end of the 9th month - 4 times. Then the cerebellum grows more slowly, and by the age of 6 its mass reaches the lower limit of the norm for an adult - 120 g.

Above the cerebellum lie the occipital lobes of the cerebral hemispheres. The cerebellum is separated from the cerebrum by a deep fissure, into which a process of the dura mater of the brain is wedged - the cerebellum, stretched over the posterior cranial fossa. Anterior to the cerebellum is the pons and medulla oblongata.

The cerebellar vermis is shorter than the hemispheres, therefore notches are formed on the corresponding edges of the cerebellum: on the anterior edge - anterior, on the posterior edge - posterior. The most protruding sections of the anterior and posterior edges form the corresponding anterior and posterior angles, and the most prominent lateral sections form the lateral angles.

A horizontal fissure running from the middle cerebellar peduncles to the posterior notch of the cerebellum divides each hemisphere of the cerebellum into two surfaces: an upper one, relatively flat and obliquely descending to the edges, and a convex lower one. With its lower surface, the cerebellum is adjacent to the medulla oblongata, so that the latter is pressed into the cerebellum, forming an invagination - the valley of the cerebellum, at the bottom of which the worm is located.

On the cerebellar vermis, the upper and lower surfaces are distinguished. Grooves running longitudinally along the sides of the worm: on the anterior surface - smaller, on the back - deeper - separate it from the cerebellar hemispheres.

The cerebellum consists of gray and white matter. The gray matter of the hemispheres and the cerebellar vermis, located in the surface layer, forms the cerebellar cortex, and the accumulation of gray matter in the depths of the cerebellum forms the cerebellar nucleus. White matter - the brain body of the cerebellum, lies in the thickness of the cerebellum and, through three pairs of cerebellar peduncles, connects the gray matter of the cerebellum with the brain stem and spinal cord.

Worm

The cerebellar vermis governs posture, tone, supportive movement, and body balance. Worm dysfunction in humans manifests itself in the form of static-locomotor ataxia.

Slices

The surfaces of the hemispheres and the vermis of the cerebellum are divided by more or less deep fissures of the cerebellum into numerous arcuately curved sheets of the cerebellum of various sizes, most of which are located almost parallel to one another. The depth of these furrows does not exceed 2.5 cm. If it were possible to straighten the leaves of the cerebellum, then the area of ​​​​its cortex would be 17 x 120 cm. Groups of convolutions form separate lobules of the cerebellum. The lobules of the same name in both hemispheres are delimited by the same groove, which passes through the worm from one hemisphere to the other, as a result of which two - right and left - lobules of the same name in both hemispheres correspond to a certain lobule of the worm.

Individual lobules form the lobes of the cerebellum. There are three such shares: anterior, posterior and flocculent-nodular.

The worm and hemispheres are covered with gray matter, inside of which is white matter. The white matter, branching, penetrates into each gyrus in the form of white stripes. On sagittal sections of the cerebellum, a peculiar pattern is visible, called the "tree of life". The subcortical nuclei of the cerebellum lie within the white matter.

10. tree of life cerebellum
11. brain body of the cerebellum
12. white stripes
13. cerebellar cortex
18. dentate nucleus
19. gate of the dentate nucleus
20. corky nucleus
21. globular nucleus
22. tent core

The cerebellum is connected to neighboring brain structures by means of three pairs of legs. The cerebellar peduncles are a system of pathways, the fibers of which follow to and from the cerebellum:

1. The inferior cerebellar peduncles run from the medulla oblongata to the cerebellum.
2. Middle cerebellar peduncles - from the pons to the cerebellum.
3. The superior cerebellar peduncles lead to the midbrain.

Nuclei

The nuclei of the cerebellum are paired accumulations of gray matter, which lie in the thickness of the white, closer to the middle, that is, the cerebellar vermis. There are the following cores:

1. the dentate lies in the medial-lower areas of the white matter. This nucleus is a wave-like curving plate of gray matter with a small break in the medial section, which is called the gate of the dentate nucleus. The jagged kernel is similar to the kernel of an olive. This similarity is not accidental, since both nuclei are connected by conductive pathways, olive-cerebellar fibers, and each gyrus of one nucleus is similar to the gyrus of the other.
2. cork is located medially and parallel to the dentate nucleus.
3. the spherical lies somewhat medially to the cork-like nucleus and can be presented in the form of several small balls on the cut.
4. the core of the tent is localized in the white matter of the worm, on both sides of its median plane, under the uvula lobule and the central lobule, in the roof of the fourth ventricle.

The nucleus of the tent, being the most medial, is located on the sides of the midline in the area where the tent protrudes into the cerebellum. Lateral to it are the spherical, corky, and dentate nuclei, respectively. These nuclei have different phylogenetic ages: nucleus fastigii belongs to the most ancient part of the cerebellum, associated with the vestibular apparatus; nuclei emboliformis et globosus - to the old part, which arose in connection with the movements of the body, and the nucleus dentatus - to the youngest, which developed in connection with movement with the help of the limbs. Therefore, with the defeat of each of these parts, various aspects of the motor function are disturbed, corresponding to different stages of phylogenesis, namely: with damage to the archicerebellum, the balance of the body is disturbed;

The nucleus of the tent is located in the white matter of the "worm", the remaining nuclei lie in the hemispheres of the cerebellum. Almost all information leaving the cerebellum is switched to its nuclei.

blood supply

arteries

Three large paired arteries originate from the vertebral and basilar arteries, delivering blood to the cerebellum:

1. superior cerebellar artery;
2. anterior inferior cerebellar artery;
3. posterior inferior cerebellar artery.

The cerebellar arteries pass along the crests of the gyri of the cerebellum without forming a loop in its grooves, as do the arteries of the cerebral hemispheres. Instead, small vascular branches extend from them into almost every groove.

Superior cerebellar artery

It arises from the upper part of the basilar artery at the border of the bridge and the brain stem before its division into the posterior cerebral arteries. The artery goes below the trunk of the oculomotor nerve, bends around the anterior cerebellar peduncle from above and, at the level of the quadrigemina, under the notch, makes a right angle turn back, branching on the upper surface of the cerebellum. Branches branch off from the artery and supply blood to:

• lower colliculi of the quadrigemina;
• superior cerebellar peduncles;
• dentate nucleus of the cerebellum;
• upper sections of the vermis and cerebellar hemispheres.

The initial parts of the branches that supply blood to the upper sections of the worm and its surrounding areas can be located within the posterior part of the notch of the cerebellum, depending on the individual size of the tentorial foramen and the degree of physiological protrusion of the worm into it. Then they cross the edge of the cerebellum and go to the dorsal and lateral parts of the upper hemispheres. This topographic feature makes the vessels vulnerable to possible compression by the most eminent part of the vermis when the cerebellum is wedged into the posterior part of the tentorial foramen. The result of such compression is partial and even complete heart attacks of the cortex of the upper hemispheres and the cerebellar vermis.

The branches of the superior cerebellar artery anastomose widely with the branches of both inferior cerebellar arteries.

Anterior inferior cerebellar artery

Departs from the initial part of the basilar artery. In most cases, the artery runs along the lower edge of the pons in an arc, convex downwards. The main trunk of the artery is most often located anterior to the root of the abducens nerve, goes outward and passes between the roots of the facial and vestibulocochlear nerves. Further, the artery goes around the top of the patch and branches on the anteroinferior surface of the cerebellum. In the region of the shred, two loops formed by the cerebellar arteries can often be located: one is the posterior lower, the other is the anterior lower.

The anterior inferior cerebellar artery, passing between the roots of the facial and vestibulocochlear nerves, gives off the labyrinth artery, which goes to the internal auditory canal and, together with the auditory nerve, penetrates into the inner ear. In other cases, the labyrinth artery departs from the basilar artery. The terminal branches of the anterior inferior cerebellar artery feed the roots of the VII-VIII nerves, the middle cerebellar peduncle, the tuft, the anteroinferior sections of the cerebellar cortex, and the choroid plexus of the IV ventricle.

The anterior villous branch of the IV ventricle departs from the artery at the level of the flocculus and enters the plexus through the lateral aperture.

Thus, the anterior inferior cerebellar artery supplies blood to:

• inner ear;
• roots of the facial and vestibulocochlear nerves;
• middle cerebellar peduncle;
• shred-nodular lobule;
• choroid plexus of the IV ventricle.

The zone of their blood supply in comparison with the rest of the cerebellar arteries is the smallest.

Posterior inferior cerebellar artery

Departs from the vertebral artery at the level of the chiasm of the pyramids or at the lower edge of the olive. The diameter of the main trunk of the posterior inferior cerebellar artery is 1.5–2 mm. The artery bends around the olive, rises, makes a turn and passes between the roots of the glossopharyngeal and vagus nerves, forming loops, then descends down between the inferior cerebellar peduncle and the inner surface of the tonsil. Then the artery turns outward and passes to the cerebellum, where it diverges into internal and external branches, the first of which rises along the worm, and the second goes to the lower surface of the cerebellar hemisphere.

An artery can form up to three loops. The first loop, directed downwards with a bulge, is formed in the region of the groove between the pons and the pyramid, the second loop with a bulge upwards is on the lower cerebellar peduncle, the third loop, directed downwards, lies on the inner surface of the tonsil. Branches from the trunk of the posterior inferior cerebellar artery to:

• ventrolateral surface of the medulla oblongata. The defeat of these branches causes the development of the Wallenberg-Zakharchenko syndrome;
• tonsil;
• lower surface of the cerebellum and its nuclei;
• roots of the glossopharyngeal and vagus nerves;
• choroid plexus of the IV ventricle through its median aperture in the form of the posterior villous branch of the IV ventricle).

Vienna

Cerebellar veins form a wide network on its surface. They anastomose with the veins of the cerebrum, brainstem, spinal cord and flow into the nearby sinuses.

The superior vein of the cerebellar vermis collects blood from the superior vermis and adjacent sections of the cortex of the upper surface of the cerebellum and flows above the quadrigemina into the great cerebral vein from below.

The inferior vein of the cerebellar vermis receives blood from the inferior vermis, the inferior surface of the cerebellum, and the tonsil. The vein goes backwards and up along the groove between the hemispheres of the cerebellum and flows into the direct sinus, less often into the transverse sinus or into the sinus drain.

The superior cerebellar veins run along the upper lateral surface of the brain and empty into the transverse sinus.

The inferior cerebellar veins, which collect blood from the inferior lateral surface of the cerebellar hemispheres, drain into the sigmoid sinus and superior petrosal vein.

Cerebellum - Neurophysiology

The cerebellum is a functional offshoot of the main cortex-spinal cord axis. On the one hand, sensory feedback closes in it, that is, it receives a copy of the afferentation, on the other hand, a copy of the efferentation from the motor centers also comes here. Technically speaking, the first signalizes the current state of the controlled variable, while the second gives an idea of ​​the required final state. By comparing the first and second, the cerebellar cortex can calculate the error, which is reported to the motor centers. So the cerebellum continuously corrects both intentional and automatic movements. In lower vertebrates, information also enters the cerebellum from the acoustic region, in which sensations related to balance are recorded, supplied by the ear and the lateral line, and in some even from the organ of smell.

Phylogenetically, the most ancient part of the cerebellum consists of a tuft and a nodule. Vestibular inputs predominate here. In evolutionary terms, the structures of the archcerebellum arise in the class of cyclostomes in lampreys, in the form of a transverse plate that spreads over the anterior part of the rhomboid fossa. In lower vertebrates, the archicerebellum is represented by paired ear-shaped parts. In the process of evolution, a decrease in the size of the structures of the ancient part of the cerebellum is noted. Archicerebellum is the most important component of the vestibular apparatus.

The "old" structures in humans also include the region of the vermis in the anterior lobe of the cerebellum, the pyramid, the uvula of the worm, and the peritoneum. The paleocerebellum receives signals mainly from the spinal cord. Paleocerebellum structures appear in fish and are present in other vertebrates.

The medial elements of the cerebellum project to the nucleus of the tent, as well as to the spherical and corky nuclei, which in turn form connections mainly with the stem motor centers. Deiters' nucleus, the vestibular motor center, also receives signals directly from the vermis and from the flocculonodular lobe.

Damage to the archi- and paleocerebellum lead primarily to imbalances, as in the pathology of the vestibular apparatus. A person is manifested by dizziness, nausea and vomiting. Oculomotor disorders in the form of nystagmus are also typical. It is difficult for patients to stand and walk, especially in the dark, for this they have to grab onto something with their hands; gait becomes staggering, as if in a state of intoxication.

Signals go to the lateral elements of the cerebellum mainly from the cortex of the cerebral hemispheres through the nuclei of the pons and inferior olive. The Purkinje cells of the cerebellar hemispheres project through the lateral dentate nuclei to the motor nuclei of the thalamus and further to the motor areas of the cerebral cortex. Through these two inputs, the cerebellar hemisphere receives information from the cortical areas that are activated in the phase of preparation for movement, that is, participating in its “programming”. Neocerebellum structures are found only in mammals. At the same time, in humans, in connection with upright walking, improvement of hand movements, they have reached the greatest development in comparison with other animals.

Thus, part of the impulses that have arisen in the cerebral cortex reaches the opposite hemisphere of the cerebellum, bringing information not about the produced, but only about the active movement planned for execution. Having received such information, the cerebellum immediately sends out impulses that correct voluntary movement, mainly by extinguishing inertia and the most rational regulation of the muscle tone of agonists and antagonists. As a result, the clarity and refinement of voluntary movements are ensured, and any inappropriate components are eliminated.

Functional plasticity, motor adaptation and motor learning

The role of the cerebellum in motor adaptation has been demonstrated experimentally. If vision is impaired, the vestibulo-ocular reflex of compensatory eye movement when turning the head will no longer correspond to the visual information received by the brain. A subject wearing prism glasses initially finds it very difficult to move correctly in the environment, but after a few days he adjusts to the anomalous visual information. At the same time, clear quantitative changes in the vestibulo-ocular reflex and its long-term adaptation were noted. Experiments with the destruction of nervous structures have shown that such motor adaptation is impossible without the participation of the cerebellum. The plasticity of cerebellar function and motor learning and the determination of their neuronal mechanisms have been described by David Marr and James Albus.

The plasticity of the function of the cerebellum is also responsible for motor learning and the development of stereotyped movements, such as writing, typing on the keyboard, etc.

Although the cerebellum is connected to the cerebral cortex, its activity is not controlled by consciousness.

Functions

The functions of the cerebellum are similar in various species, including humans. This is confirmed by their disturbance in case of damage to the cerebellum in the experiment in animals and the results of clinical observations in diseases affecting the cerebellum in humans. The cerebellum is a brain center that is extremely important for coordinating and regulating motor activity and maintaining posture. The cerebellum works mainly reflexively, maintaining the balance of the body and its orientation in space. It also plays an important role in locomotion.

Accordingly, the main functions of the cerebellum are:

1. movement coordination
2. balance regulation
3. regulation of muscle tone

Conducting paths

The cerebellum is connected to other parts of the nervous system by numerous pathways that run in the cerebellar peduncles. Distinguish between afferent and efferent pathways. Efferent pathways are present only in the upper legs.

Cerebellar pathways do not cross at all or cross twice. Therefore, with a half lesion of the cerebellum itself or a unilateral lesion of the cerebellar peduncles, the symptoms of the lesion develop on the sides of the lesion.

upper legs

Efferent pathways pass through the superior cerebellar peduncles, with the exception of Govers's afferent pathway.

1. Anterior spinal-cerebellar tract - the first neuron of this path starts from the proprioreceptors of the muscles, joints, tendons and periosteum and is located in the spinal ganglion. The second neuron is the cells of the posterior horn of the spinal cord, the axon of which passes to the opposite side and rises up in the anterior part of the lateral column, passes the medulla oblongata, the pons, then crosses again and through the upper legs enter the cortex of the cerebellar hemispheres, and then into the dentate nucleus .
2. The dentate-red path starts from the dentate nucleus and passes through the superior cerebellar peduncles. These paths double-cross and end at red nuclei. The axons of the neurons of the red nuclei form the rubrospinal pathway. After leaving the red nucleus, this path crosses again, descends in the brainstem, as part of the lateral column of the spinal cord, and reaches the α- and γ-motoneurons of the spinal cord.
3. Cerebellar-thalamic path - goes to the nuclei of the thalamus. Through them, it connects the cerebellum with the extrapyramidal system and the cerebral cortex.
4. Cerebellar-reticular path - connects the cerebellum with the reticular formation, from which, in turn, the reticular-spinal path begins.
5. The cerebellar-vestibular path is a special path, since, unlike other pathways that begin in the nuclei of the cerebellum, it is the axons of Purkinje cells heading to the lateral vestibular nucleus of Deiters.

Medium legs

Through the middle cerebellar peduncle are afferent pathways that connect the cerebellum to the cerebral cortex.

1. The fronto-bridge-cerebellar path starts from the anterior and middle frontal gyri, passes through the anterior thigh of the internal capsule to the opposite side and switches on the cells of the pons varolii, which are the second neuron of this path. From them, it enters the contralateral middle cerebellar peduncle and ends on the Purkinje cells of its hemispheres.
2. The temporal-bridge-cerebellar path - starts from the cells of the cortex of the temporal lobes of the brain. Otherwise, its course is similar to that of the fronto-bridge-cerebellar path.
3. Occipital-bridge-cerebellar path - starts from the cells of the cortex of the occipital lobe of the brain. Transmits visual information to the cerebellum.

lower legs

In the lower legs of the cerebellum, afferent pathways run from the spinal cord and brain stem to the cerebellar cortex.

1. The posterior spinal cord connects the cerebellum to the spinal cord. Conducts impulses from proprioreceptors of muscles, joints, tendons and periosteum, which reach the posterior horns of the spinal cord as part of sensory fibers and posterior roots of the spinal nerves. In the posterior horns of the spinal cord, they switch to the so-called. Clark cells, which are the second neuron of deep sensitivity. The axons of Clark cells form the Flexig pathway. They pass in the back of the lateral column on their side and, as part of the lower legs of the cerebellum, reach its cortex.
2. Olive-cerebellar path - begins in the nucleus of the inferior olive on the opposite side and ends on the Purkinje cells of the cerebellar cortex. The olive-cerebellar path is represented by climbing fibers. The nucleus of the inferior olive receives information directly from the cerebral cortex and thus conducts information from its premotor areas, that is, the areas responsible for planning movements.
3. Vestibulo-cerebellar path - starts from the upper vestibular nucleus of Bekhterev and through the lower legs reaches the cerebellar cortex of the flocculo-nodular region. The information of the vestibulo-cerebellar pathway, having switched on the Purkinje cells, reaches the nucleus of the tent.
4. Reticulo-cerebellar path - starts from the reticular formation of the brain stem, reaches the cortex of the cerebellar vermis. Connects the cerebellum and the basal ganglia of the extrapyramidal system.

Cerebellum - Symptoms of lesions

Damage to the cerebellum is characterized by disorders of statics and coordination of movements, as well as muscle hypotension. This triad is characteristic of both humans and other vertebrates. At the same time, the symptoms of cerebellar damage are described in most detail for humans, since they are of direct applied importance in medicine.

Damage to the cerebellum, especially its worm, usually leads to a violation of the statics of the body - the ability to maintain a stable position of its center of gravity, which ensures stability. When this function is disturbed, static ataxia occurs. The patient becomes unstable, therefore, in a standing position, he seeks to spread his legs wide, balance with his hands. Especially clearly static ataxia is manifested in the Romberg position. The patient is invited to stand up, tightly moving his feet, slightly raise his head and stretch his arms forward. In the presence of cerebellar disorders, the patient in this position is unstable, his body sways. The patient may fall. In the case of damage to the cerebellar vermis, the patient usually sways from side to side and often falls back, with pathology of the cerebellar hemisphere, he tends mainly towards the pathological focus. If the static disorder is moderately expressed, it is easier to identify it in a patient in the so-called complicated or sensitized Romberg position. In this case, the patient is invited to put his feet on the same line so that the toe of one foot rests on the heel of the other. The assessment of stability is the same as in the usual Romberg position.

Normally, when a person is standing, the muscles of his legs are tense, with the threat of falling to the side, his leg on this side moves in the same direction, and the other leg comes off the floor. With the defeat of the cerebellum, mainly its worm, the patient's support and jump reactions are disturbed. Violation of the support reaction is manifested by the instability of the patient in a standing position, especially if his legs are closely shifted at the same time. Violation of the jump reaction leads to the fact that if the doctor, standing behind the patient and insuring him, pushes the patient in one direction or another, then the latter falls with a small push.

The gait of a patient with cerebellar pathology is very characteristic and is called "cerebellar". The patient, due to the instability of the body, walks uncertainly, spreading his legs wide, while he is “thrown” from side to side, and if the hemisphere of the cerebellum is damaged, it deviates when walking from a given direction towards the pathological focus. The instability is especially pronounced when cornering. During walking, the human torso is excessively straightened. The gait of a patient with a cerebellar lesion is in many ways reminiscent of the gait of a drunk person.

If static ataxia is pronounced, then patients completely lose the ability to control their body and cannot not only walk and stand, but even sit.

Predominant lesion of the cerebellar hemispheres leads to a breakdown of its counter-inertial influences and, in particular, to the occurrence of dynamic ataxia. It is manifested by the awkwardness of the movements of the limbs, which is especially pronounced with movements that require precision. To identify dynamic ataxia, a number of coordination tests are performed.

Muscular hypotension is detected with passive movements made by the examiner in various joints of the patient's limbs. Damage to the cerebellar vermis usually leads to diffuse hypotension of the muscles, while with damage to the cerebellar hemisphere, a decrease in muscle tone is noted on the side of the pathological focus.

Pendulum reflexes are also due to hypotension. When examining the knee reflex in a sitting position with legs hanging freely from the couch after a blow with a hammer, several “swinging” movements of the lower leg are observed.

Asynergia is the loss of physiological synergistic movements during complex motor acts.

The most common asynergy tests are:

1. The patient, standing with shifted legs, is offered to bend over backwards. Normally, simultaneously with the tilting of the head, the legs synergistically bend at the knee joints, which allows maintaining the stability of the body. With cerebellar pathology, there is no friendly movement in the knee joints and, throwing back the head, the patient immediately loses balance and falls in the same direction.
2. The patient, standing with his legs shifted, is invited to lean on the palms of the doctor, who then suddenly removes them. If the patient has cerebellar asynergy, he falls forward. Normally, there is a slight deviation of the body back or the person remains motionless.
3. The patient, lying on his back on a hard bed without a pillow, with his legs spread apart to the width of the shoulder girdle, is offered to cross his arms over his chest and then sit down. Due to the absence of friendly contractions of the gluteal muscles, a patient with cerebellar pathology cannot fix the legs and pelvis to the support area, as a result, he cannot sit down, while the patient's legs, breaking away from the bed, rise up.

Cerebellum - Pathology

Cerebellar lesions occur in a wide range of diseases. Based on the ICD-10 data, the cerebellum is directly affected in the following pathologies:

Neoplasms

Cerebellar neoplasms are most commonly represented by medulloblastomas, astrocytomas, and hemangioblastomas.

Abscess

Cerebellar abscesses account for 29% of all brain abscesses. They are localized more often in the cerebellar hemispheres at a depth of 1-2 cm. They are small in size, round or oval in shape.

There are metastatic and contact abscesses of the cerebellum. Metastatic abscesses are rare; develop as a result of purulent diseases of distant parts of the body. Sometimes the source of the infection cannot be identified.

Contact abscesses of otogenic origin are more common. The ways of infection in them are either the bone canals of the temporal bone or the vessels that drain blood from the middle and inner ear.

hereditary diseases

A group of hereditary diseases is accompanied by the development of ataxia.

In some of them, a predominant lesion of the cerebellum is noted.

Hereditary cerebellar ataxia of Pierre Marie

Hereditary degenerative disease with a primary lesion of the cerebellum and its pathways. The mode of inheritance is autosomal dominant.

With this disease, a degenerative lesion of the cells of the cortex and nuclei of the cerebellum, spinocerebellar pathways in the lateral cords of the spinal cord, in the nuclei of the bridge and the medulla oblongata is determined.

Olivopontocerebellar degenerations

A group of hereditary diseases of the nervous system, characterized by degenerative changes in the cerebellum, nuclei of the inferior olives and the pons of the brain, in rare cases - the nuclei of the cranial nerves of the caudal group, to a lesser extent - damage to the pathways and cells of the anterior horns of the spinal cord, basal ganglia. Diseases differ in the type of inheritance and a different combination of clinical symptoms.

Alcoholic cerebellar degeneration

Alcoholic cerebellar degeneration is one of the most common complications of alcohol abuse. It develops more often in the 5th decade of life after many years of ethanol abuse. It is caused both by the direct toxic effect of alcohol, and by electrolyte disturbances caused by alcoholism. Severe atrophy of the anterior lobes and the upper part of the cerebellar vermis develops. In the affected areas, an almost complete loss of neurons is revealed in both the granular and molecular layers of the cerebellar cortex. In advanced cases, the dentate nuclei may also be involved.

Multiple sclerosis

Multiple sclerosis is a chronic demyelinating disease. With it, there is a multifocal lesion of the white matter of the central nervous system.

Morphologically, the pathological process in multiple sclerosis is characterized by numerous changes in the brain and spinal cord. The favorite localization of the foci is the periventricular white matter, the lateral and posterior cords of the cervical and thoracic spinal cord, the cerebellum and the brain stem.

Cerebral circulation disorders

Hemorrhage in the cerebellum

Cerebral cerebrovascular accidents can be either ischemic or hemorrhagic.

Cerebellar infarction occurs when blockage of the vertebral, basilar or cerebellar arteries and, with extensive damage, is accompanied by severe cerebral symptoms, impaired consciousness. Blockage of the anterior inferior cerebellar artery leads to a heart attack in the cerebellum and pons, which can cause dizziness, tinnitus, nausea on the side of the lesion - paresis of facial muscles, cerebellar ataxia, Horner's syndrome. When blockage of the superior cerebellar artery often occurs dizziness, cerebellar ataxia on the side of the focus.

Hemorrhage in the cerebellum is usually manifested by dizziness, nausea and repeated vomiting while maintaining consciousness. Patients often suffer from headache in the occipital region, they usually have nystagmus and ataxia in the extremities. In the event of a cerebellar-tentorial displacement or wedging of the cerebellar tonsils into the foramen magnum, a disturbance of consciousness develops up to coma, hemi- or tetraparesis, lesions of the facial and abducent nerves.

Traumatic brain injury

Cerebellar contusions dominate among lesions of the formations of the posterior cranial fossa. Focal lesions of the cerebellum are usually caused by an impact mechanism of injury, as evidenced by frequent fractures of the occipital bone below the transverse sinus.

Cerebral symptoms in cerebellar injuries often have an occlusive color due to the proximity to the CSF outflow pathways from the brain.

Among the focal symptoms of cerebellar contusion, unilateral or bilateral muscular hypotension, coordination disorders, and large tonic spontaneous nystagmus dominate. Characterized by localization of pain in the occipital region with irradiation to other areas of the head. Often, one or another symptomatology from the side of the brain stem and cranial nerves manifests itself simultaneously. With severe damage to the cerebellum, respiratory disorders, hormetonia, and other life-threatening conditions occur.

Due to the limited subtentorial space, even with a relatively small amount of damage to the cerebellum, dislocation syndromes often unfold with infringement of the medulla oblongata by the cerebellar tonsils at the level of the occipital-cervical dural funnel or infringement of the midbrain at the level of the tenon due to the upper parts of the cerebellum being displaced from bottom to top.

Malformations

MRI. Arnold's syndrome - Chiari I. The arrow indicates the protrusion of the tonsils of the cerebellum into the lumen of the spinal canal

Cerebellar malformations include several diseases.

Allocate total and subtotal agenesis of the cerebellum. Total agenesis of the cerebellum is rare, combined with other severe anomalies in the development of the nervous system. Most often, subtotal agenesis is observed, combined with malformations of other parts of the brain. Hypoplasia of the cerebellum occurs, as a rule, in two variants: reduction of the entire cerebellum and hypoplasia of individual parts while maintaining the normal structure of its other departments. They can be unilateral or bilateral, as well as lobar, lobular and intracortical. There are various changes in the configuration of the sheets - allogyria, polygyria, agyria.

Dandy-Walker Syndrome

Dandy-Walker syndrome is characterized by a combination of cystic enlargement of the fourth ventricle, total or partial aplasia of the cerebellar vermis, and supratentorial hydrocephalus.

Arnold-Chiari Syndrome

Arnold-Chiari syndrome includes 4 types of diseases, designated Arnold-Chiari syndrome I, II, III and IV, respectively.

Arnold-Chiari I syndrome - descent of the cerebellar tonsils more than 5 mm beyond the foramen magnum into the spinal canal.

Arnold-Chiari II syndrome - descent into the spinal canal of the structures of the cerebellum and brain stem, myelomeningocele and hydrocephalus.

Arnold-Chiari III syndrome - occipital encephalocele in combination with signs of Arnold-Chiari II syndrome.

Arnold-Chiari IV syndrome - aplasia or hypoplasia of the cerebellum.