Bridge its structure and functional significance. Functions and structure of the brain bridge, its description. The structure of the brain

Bridge, pons, represents a thick white shaft from the side of the base of the brain, bordering behind the upper end of the medulla oblongata, and in front - with the legs of the brain. The lateral border of the bridge is an artificially drawn line through the roots of the trigeminal and facial nerves, linea trigeminofacialis. Laterally from this line are the middle cerebellar peduncles, pedunculi cerebellares medii, plunging on both sides into the cerebellum. The dorsal surface of the bridge is not visible from the outside, as it is hidden under the cerebellum, forming the upper part of the rhomboid fossa (the bottom of the IV ventricle). The ventral surface of the pons is fibrous in nature, the fibers generally running transversely and running into the pedunculi cerebellares medii. A gentle groove, sulcus basilaris, runs along the midline of the ventral surface, in which lies a. basilaris.

The internal structure of the bridge. On the transverse sections of the bridge, you can see that it consists of a larger anterior, or ventral, part, pars ventralis pontis, and a smaller dorsal, pars dorsalis pontis. The boundary between them is a thick layer of transverse fibers - the trapezoid body, corpus trapezoideum, the fibers of which belong to the auditory pathway. In the region of the trapezoid body, there is a nucleus, which is also related to the auditory pathway, the nucleus dorsalis corporis trapezoidei. Pars ventralis contains longitudinal and transverse fibers, between which are scattered their own nuclei of gray matter, nuclei pontis. The longitudinal fibers belong to the pyramidal tracts, to the fibrae corticopontine, which are connected with their own nuclei of the bridge, from which the transverse fibers originate, going to the cerebellar cortex, tractus pontocerebellaris. This whole system of pathways connects the cortex of the hemispheres through the bridge big brain with the cerebral cortex.

The more developed the cerebral cortex, the more developed the bridge and the cerebellum. Naturally, the bridge is most pronounced in humans, which is a specific feature of the structure of his brain. In pars dorsalis there is a formatio reticularis pontis, which is a continuation of the same formation of the medulla oblongata, and on top reticular formation- the bottom of the rhomboid fossa lined with ependyma with the nuclei of the cranial nerves (VIII-V pairs) lying under it. In pars dorsalis, the pathways of the medulla oblongata also continue, located between middle line and nucleus dorsalis corporis trapezoidei and included in the medial loop, lemniscus medialis; in the latter, the ascending paths of the medulla oblongata, tractus bulbothalamicus, cross.

The bridge of the brain performs many important functions, they are associated with the fact that it contains the nuclei of the cranial nerves. This part of the hindbrain performs motor, sensory, conduction and integrative functions.

This department plays an important role, both in the connection of different departments, and in itself strongly influences the life of a person, it controls reflexes and conscious behavior.

Structure

The department is part of the hindbrain. The structure and functions of the bridge are very closely related, as in any other structure. He took a position in front of the cerebellum, being the department between the middle and medulla oblongata.

It is separated from the first by the beginning of the 4th pair of cranial nerves, and from the second by a transverse groove. Outwardly, it resembles a roller with a furrow, with nerves passing through it, they are responsible for the sensory abilities of the skin of the face. In the furrow there was a place for the basilar arteries, their features include the fact that they supply blood to the back of the brain.

This department has a special rhomboid fossa, located in the back of the pons varilla. From above, the fossa is limited by the brain strips, and above them are the facial mounds.

Above them there is a median eminence, and next to me is a blue spot, which is responsible for the feeling of anxiety, it includes many nerve endings of the norepinephrine type. The pathways look like thick fibers of nervous tissue that run from the pons to the cerebellum. Thus, they form the handles of the bridge and the peduncles of the cerebellum.

Among other things, the structure of the bridge has a "tire", which is an accumulation of gray matter. This gray matter is the centers of the cranial nerves and the parts that contain pathways. That is, the upper brain part is reserved for the centers that have a connection with the cranial nerves (fifth, sixth, seventh and eighth pairs).

Good to know: The cerebral cortex, structure and functions

Speaking of pathways, the medial loop and the lateral loop pass through this part. The same tire contains the reticular formation, it is part of six nuclei and contains structures that are responsible for auditory analyzers.

At the base are paths that run from the cerebral cortex to different parts:

brain bridge;
medulla;
spinal cord;
cerebellum.

And the blood supply occurs due to the arteries, which belong to the vertebrobasilar basin.

Conductor function

The Variliev Bridge was named for a reason. The thing is that absolutely all the paths that go both in the ascending and in the descending direction pass through this department.

They connect the forebrain and other structures such as the cerebellum, spinal cord and others.

Motor and sensory functions

Speaking in more detail about motor and sensory function, let's talk about the cranial nerves. Mentioning the cranial nerves, it should be noted the ternary or mixed nerve (V pair). This pair of nerves is responsible for the movement of the chewing muscles, as well as the muscles that are responsible for the tension of the tympanic membrane and the palatine curtain.

Afferent connections of nerve cells from receptors that are located in the skin of the human face, nasal mucosa, 60% of the tongue, eyeball and teeth go to the sensory part of the trigeminal nerve. The sixth pair, or the so-called abducens nerve, is responsible for the movement of the eyeballs, namely for its rotation to the outside.

One of the most important functions for human interaction is the 7th pair, it is responsible for the innervation of the muscles that allow the production of facial expressions. In addition, three glands are controlled by the facial nerve: salivary, sublingual, and submandibular. These glands provide reflexes such as salivation and swallowing.

The bridge also has a connection with the vestibulocochlear nerve. It is clear from the name that the cochlear part reaches the cochlear nuclei, but the vestibular part ends in the triangular nucleus. The eighth pair of nerves is responsible for the analysis of vestibular stimuli, it determines the degree of their severity and where they are directed.

Integrating function

These bridge functions connect parts of the brain called the cerebral hemispheres. Also, all other paths pass through the bridge, both ascending and descending, connecting it with many departments of the central nervous system. These include the spinal cord, cerebellum, and cerebral cortex.

Impulses passing through the bridge-cerebellar pathways of the cerebral cortex have their effect on the work of the cerebellum. The bark cannot influence directly, therefore it uses the bridge as an intermediary for these purposes. The bridge regulates the medulla oblongata, influencing the centers that are responsible for the respiratory process and its intensity.

Results

Now it became clear that the bridge is the most important part of the central nervous system, providing conscious control of the body together with the cerebellum.

In addition, it helps a person to perceive their own position in space. Under his responsibility is the sensitivity of the tongue, face, nasal mucosa and ocular conjunctiva.

The bridge (pons) is an elevation located between the medulla oblongata and midbrain, 25–27 mm long. Its lower border is the pyramids and olives of the medulla oblongata, the upper one is the legs of the brain, the lateral one is the line passing between the roots of the trigeminal and facial nerves. On the dorsal side, the upper border of the bridge is the upper cerebellar peduncles (pedunculi cerebellares superiores) and the upper medullary velum (velum medullare superius), and from below is a deep horizontal groove, from which, starting from the main groove, the roots of the efferent (VI pair), facial ( VII pair) and auditory (VIII pair) nerves.

The bridge is divided into front and rear parts. The anterior part of the bridge (pars anterior pontis) is convex and formed by transverse nerve fibers connecting the cells of the cortex of the cerebral hemispheres with the nuclei of the bridge (nucll. pontis) and then with the cerebellar cortex. Together with them, the fibers from the cerebellar cortex to the cerebral cortex go in the opposite direction. These fibers cover the perpendicular bundles of the pyramidal path (Fig. 465), and then in the lateral parts of the bridge are collected in the middle cerebellar peduncles (pedunculi cerebellares medii). Along the midline of the bridge between the elevations formed by the fibers of the pyramidal path, there is a basilar groove (sulcus basilaris), in which the artery of the same name lies.

465. Diagram of the arrangement of conductive paths and nuclei on the cross section of the bridge.
1 - nuclei of the V pair; 2 - nuclei of the VIII pair; 3-tr. rubrospinalis; 4-tr. spinocerebellaris anterior; 5-tr. spinocerebellaris posterior; 6-tr. spinothalamicus lateralis; 7 - VII pair; 8 - VI pair; 9-tr. corticospinalis (pyramidalis); 10 - fast. longitudinalis medialis; 11-tr. spinothalamicus anterior: 12 - tr. tectospinalis; 13-tr. reticulospinalis.

The dorsal part of the bridge is thinner and participates in the formation of the upper part of the rhomboid fossa. In the dorsal part of the bridge are the nuclei of the V, VI, VII, VIII cranial nerves, the reticular formation, and the superior olive. The latter is associated with the auditory nuclei and has connections with the reticular formation of the medulla oblongata and midbrain.

The sensory and motor nuclei of the trigeminal nerve (V pair) are located in the upper part of the bridge. The sensitive nucleus (nucleus sensorius n. trigemini) is the site of switching of the processes of the cells of the trigeminal ganglion. The motor nucleus (nucl. motorius n. trigemini) consists of small pyramidal cells that innervate the masticatory muscles.

The nucleus of the abducens nerve (nucl. n. abducentis) (VI pair) is located in the lower part of the bridge near the midline.

The nucleus of the facial nerve (nucl. n. facialis) is formed by motor cells that innervate the mimic muscles. They are arranged in a mesh formation. The fibers of the nucleus form a knee that goes around the nucleus of the abducens nerve. Behind the motor nucleus of the facial nerve lies the superior salivary nucleus (nucl. salivatorius superior), where fibers begin to innervate the lacrimal, sublingual, and submandibular glands. Lateral to the superior salivary nucleus is the nucleus of the solitary pathway (nucl. tr. solitarii), (the nucleus of the VII pair), which has the form of a column reaching the medulla oblongata. In the nucleus, the sensitive fibers of the cells of the knee node (gangl. geniculi), which are conductors of taste sensations, terminate.

The nuclei of the vestibulocochlear nerve (n. vestibulocochlearis) are located in the lower lateral part of the back of the bridge.

Olives. The upper olive (oliva superior) has nuclei lying in the lateral sections of the bridge at the level of the trapezoid body, that is, on the border of its ventral and dorsal parts.

The reticular formation (formatio reticularis) has several nuclei, predominantly oriented in the plane of the cross section (Fig. 465).
1. The lateral reticular nucleus (nucl. reticularis lateralis) lies lateral and below the lower olive. Sends its fibers through the opposite lower cerebellar peduncles to the cerebellum.

2. The reticular core of the pons (Bechterew) (nucl. reticularis tegmenti pontis) surrounds the own core of the bridge. Some of its fibers reach the cerebellar worm, others, crossing, end in the cerebellar hemispheres.

3. Paramedial reticular nucleus (nucl. paramedialis) is medial and dorsal to the lower olive. Part of the fibers crosses and reaches the vermis, hemispheres and tent nucleus of the cerebellum.

4. Reticular giant cell nucleus (nucl. retucularis gigantocellularis) represents 2/3 of the volume of the reticular formation. It is located dorsal to the superior olive, at the top it extends to the nucleus of the facial nerve. Long processes of cells of the giant cell nucleus reach the overlying and underlying parts of the brain.

5. The caudal reticular nucleus (nucl. reticularis caudalis) is located above the previous one.

6. The oral reticular nucleus (nucl. reticularis oralis) is located on the border with the midbrain. It continues into the mesencephalic reticular formation. The fibers of the caudal and oral nuclei, together with the fibers of the giant cell nucleus, form ascending and descending fiber systems.

The trapezoidal body (corpus trapezoideum) is located between the anterior and posterior parts of the bridge in the form of a 2-3 mm wide sill. It is formed by the own nuclei of the trapezoid body (nucl. proprius), as well as by the fibers of the ventral and dorsal auditory nuclei (nucl. cochleares anterior et posterior). The processes of the cells of the nuclei of the trapezoid body, the anterior and posterior nuclei are combined into a lateral loop (lemniscus lateralis), which also has its own nucleus (nucl. lemniscus lateralis). The trapezoid body, the anterior and posterior nuclei, and the lateral loop are involved in the formation of the auditory pathway.

Age features. The bridge in newborns lies 5 mm above the back of the Turkish saddle. By the age of 2-3, it descends onto the slope of the skull. The nuclei of the cranial nerves are well differentiated, the fibers of the cortical-spinal tract are covered with myelin by the age of 8.

The brain and spinal cord are one of the independent structures in the human body, but not many people know that for their normal functioning and interaction with each other, the Varolii bridge is necessary.

What is Varolii formation and what functions does it perform, you can learn all this from this article.

General information

Varoliev Bridge is a formation in nervous system, which is located between the middle and medulla oblongata. Through it stretch the bundles of the upper parts of the brain, as well as veins and arteries. In the pons itself, there are nuclei of the central nerves in the cranial brain, which are responsible for the masticatory function of a person. In addition, it helps to ensure the sensitivity of the entire face, as well as the mucous membranes of the eyes and sinuses. Education performs two functions in the human body: binding and conducting. The bridge got its name in honor of the Bolognese anatomist Constanzo Varolia.

The structure of the varoli formation

Education is located on the surface of the brain.
If we talk about the internal structure of the bridge, then it contains an accumulation of white matter, where the nuclei of gray matter are located. In the back of the formation are the nuclei, consisting of 5,6,7, and 8 pairs of nerves. One of the most important structures located on the bridge is the reticular formation. It performs a particularly important function, it is responsible for the activation of all departments located above.
The pathways are represented by thickened nerve fibers that connect the pons to the cerebellum, thus forming the brooks of the formation itself and the cerebellar peduncles.

It saturates with blood the Varolian bridge of the artery of the vertebrobasilar basin.
Outwardly, it looks like a roller, which is attached to the brain stem. The cerebellum is attached to it from the back. In its lower part there is a transition to the medulla oblongata, and from the upper part to the middle. Basic characteristic feature Varolieva formation is that it contains a mass of pathways and nerve endings in the brain.

Four pairs of nerves diverge directly from the bridge:

ternary;
diverting;
facial;
auditory.

Formation in the prenatal period

The formation of varoli begins to form even in the embryonic period from the rhomboid bladder. The bubble, in the process of its maturation and formation, is also divided into oblong and posterior. In the process of formation, the hindbrain gives rise to the origin of the cerebellum, and the bottom and its walls become the components of the bridge. The cavity of the rhomboid bladder will subsequently be common.
The nuclei of the cranial nerves at the stage of formation are located in the medulla oblongata and only with time do they move directly to the bridge.

When the baby is born, the bridge is located just above the back of the Turkish saddle. Only after 2-3 years, he begins to rise and thus is fixed in a permanent place for him - the upper part of the skull.

At the age of 8, all spinal fibers begin to grow in a myelin sheath in a child.

VM functions

As mentioned earlier, the Varoliev bridge contains a lot of various functions necessary for the normal functioning of the human body.

Functions of the Varolii education:

controlling function, behind purposeful movements in the entire human body;
perception of the location of the body in space and time;
sensitivity of taste, skin, and mucous membranes of the nose and eyeballs;
facial expression;
eating: chewing, salivation and swallowing;
conductor, through its paths nerve endings pass to the cerebral cortex, as well as the spinal cord; interactive.
CM is used to communicate between the anterior and posterior parts of the brain;
hearing perception.

It contains the centers from which the cranial nerves exit. They are responsible for swallowing, chewing and the perception of skin sensitivity.
The nerves extending from the bridge contain motor fibers (provide the rotation of the eyeballs).

Triple nerves of the fifth pair affect the tension of the muscles of the palate, as well as the tympanic membrane in the cavity of the auricle.

The nucleus of the facial nerve is located in the Varolium formation, which is responsible for the motor, autonomic and sensory functions. In addition, the center depends on its normal functioning. respiratory system medulla oblongata.

VM pathologies

Like any organ in the human body, the VM can also stop functioning and the following diseases become the reason for this:

cerebral artery stroke;
multiple sclerosis;
head injury. Can be obtained at any age, including during childbirth;
tumors (malignant or benign) of the brain.

In addition to the main causes that can provoke brain pathologies, it is necessary to know the symptoms of such a lesion:

the process of swallowing and chewing is disturbed;
loss of sensitivity of the skin;
nausea and vomiting;
- these are eye movements in one specific direction, as a result of such movements, the head can often begin to spin, up to loss of consciousness;
can double in the eyes, with sharp turns of the head;
disturbances in the functioning of the motor system, paralysis of certain parts of the body, muscles or tremor in the hands;
in case of violations in the work of the facial nerves, the patient may experience complete or partial anemia, lack of strength in the facial nerve;
speech disorders;
asthenia - a decrease in the strength of muscle contraction, rapid muscle fatigue;
- incompatibility between the task of the performed movement and muscle contraction, for example, when walking, a person can raise his legs much higher than necessary or, on the contrary, can stumble over small bumps;
snoring, in cases where it has never been observed before.

Conclusion

From this article, we can draw such conclusions that the Varoli formation is an integral part of the human body. Without this education all parts of the brain cannot exist and perform their functions.

Without the Varoliev bridge, a person could not: eat, drink, walk and perceive the world the way he is. Therefore, there is only one conclusion, this small formation in the brain is extremely important and necessary for every person and living being in the world.

The internal structure of the bridge. On the transverse sections of the bridge, you can see that it consists of a larger anterior, or ventral, part, pars ventralis pontis, and a smaller dorsal, pars dorsalis pontis. The boundary between them is a thick layer of transverse fibers - the trapezoid body, corpus trapezoideum, the fibers of which belong to the auditory pathway. In the region of the trapezoid body, there is a nucleus, which is also related to the auditory pathway, the nucleus dorsalis corporis trapezoidei. Pars ventralis contains longitudinal and transverse fibers, between which are scattered their own nuclei of gray matter, nuclei pontis. The longitudinal fibers belong to the pyramidal tracts, to the fibrae corticopontine, which are connected with their own nuclei of the bridge, from which the transverse fibers originate, going to the cerebellar cortex, tractus pontocerebellaris. This entire system of pathways connects the cortex of the cerebral hemispheres with the cortex of the cerebellum through the bridge.

The more developed the cerebral cortex, the more developed the bridge and the cerebellum. Naturally, the bridge is most pronounced in humans, which is a specific feature of the structure of his brain. In pars dorsalis there is a formatio reticularis pontis, which is a continuation of the same formation of the medulla oblongata, and on top of the reticular formation is the bottom of the rhomboid fossa lined with ependyma with the nuclei of the cranial nerves (VIII-V pairs) lying underneath. In the pars dorsalis, the pathways of the medulla oblongata also continue, located between the midline and the nucleus dorsalis corporis trapezoidei and are part of the medial loop, lemniscus medialis; in the latter, the ascending paths of the medulla oblongata, tractus bulbothalamicus, cross.