N. centripetal) N., formed by sensitive nerve fibers and conducting nervous excitation from receptors to nerve centers.

Large medical dictionary. 2000 .

See what a “sensory nerve” is in other dictionaries:

The nerve through which afferent information from peripheral parts of the body enters the central nervous system. Various sensory nerves transmit information to the brain about temperature, pain, touch, food taste, etc. For comparison:... ... Medical terms

SENSITIVE NERVE, SENSORY NERVE- (sensory nerve) a nerve through which afferent information from peripheral parts of the body enters the central nervous system. Various sensory nerves transmit information to the brain about temperature, pain, touch, taste of food, etc.... ... Explanatory dictionary of medicine

SENSITIVE, sensitive, sensitive; sensitive, sensitive, sensitive. 1. Capable of vividly feeling, perceiving, having developed feelings, impressionable. “He was kind and sensitive, but cold and somewhat arrogant... Ushakov's Explanatory Dictionary

The nerve through which impulses arrive from the central nervous system, ensuring the active activity of the muscles and glands located in the human body. For comparison: The nerve is sensitive. Source: Medical Dictionary... Medical terms

MOTOR NERVE- (motor nerve) a nerve through which impulses arrive from the central nervous system, ensuring the active activity of the muscles and glands located in the human body. For comparison: The nerve is sensitive... Explanatory dictionary of medicine

- (n. afferens) see Sensory nerve... Large medical dictionary

- (n. centripetalis) see Sensory nerve... Large medical dictionary

The eighth cranial sensory nerve (VIII), which carries impulses from the vestibular apparatus and the organ of Corti of the inner ear from the inner ear to the brain. This nerve has two parts: the vestibular nerve and... Medical terms

VESTICOCHELLAR NERVE, AUDITORY NERVE- (auditory nerve) the eighth cranial sensory nerve (VIII), through which impulses from the vestibular apparatus and the organ of Corti of the inner ear arrive from the inner ear to the brain. This nerve has two parts: the nerve of the vestibule... ... Explanatory dictionary of medicine

The fifth (largest) mixed cranial nerve (V), which along its course is divided into three branches: the ophthalmic (sensitive), maxillary (sensitive) and mandibular (mixed) nerves. Motor fibers innervate... ... Medical terms

Mechanical stimulation turns into a nervous process in the tactile receptors themselves, a special place among which in humans is occupied by the tactile Meissnerian corpuscles. The excitation that arises in them is transmitted along nerve fibers, which are sensitive conductors, to the central nervous system. The paths of sensitive conductors are very diverse. What they have in common is that they enter the peripheral nerve, which is a nerve trunk. Both sensory and motor fibers are created in this nerve trunk. Before entering the spinal cord, the sensory (afferent) and motor (efferent) nerves are separated: all the motor nerves make up the anterior pair of spinal roots, and the sensory nerves make up the posterior pair of spinal roots.

For the most part, the nerves of the human body are mixed, and therefore, when they are damaged, sensory disorders are almost always combined with motor disorders. However, in some cases, due to the unequal vulnerability of the fibers, the latter are selectively affected (for example, diphtheria toxin affects motor fibers more strongly, and the influenza virus affects sensitive ones). But this position applies to the peripheral nerves before the divergence of sensory and motor fibers in the spinal cord.

Here the anterior (motor) roots leave the spinal cord and go again to the periphery, forming a common nerve trunk with sensory fibers. The path from the periphery to the spinal cord and back to the periphery is the nervous one

the path of spinal motor reflexes, the most elementary in their organization.

Otherwise, the path of sensory or sensory nerves that conduct mechanical stimulation develops. These nerves pass through the posterior spinal ganglion and divide into ascending and descending branches, which give off branches to various cells of the spinal cord. The descending branches end in the same segment of the spinal cord, and the ascending branches rise to the medulla oblongata, where they end in the nuclei from which nerve fibers go to the thalamus opticus and further to the cerebral cortex. On this path, the sensory nerves have, as it were, two switching stations: one in the spinal ganglion, the other in the medulla oblongata.

In diseases of the nervous system, changes in the localization of sensory nerves along this entire path are clearly distinguishable. Sensitive fibers belonging to one dorsal root or to one segment supply a certain continuous area on the skin called the radicular sensitivity zone. Therefore, it is easy for a neurologist to distinguish a disorder of skin sensitivity of spinal origin from disorders of tactile sensitivity of peripheral origin.

The further course of the sensory nerves that conduct stimulation of tactile receptors can be judged by sensitivity disorders with lesions of the visual thalamus. In this case, tactile sensitivity is most severely upset only on one half of the body, and the skin sensitivity of the hand suffers more than the skin sensitivity of the leg. With this lesion, the boundary between tactile and pain sensitivity disappears. A simple touch causes pain. Such painfully increased sensitivity is called hyperesthesia (as opposed to loss of sensitivity, anesthesia). This type of disorder indicates that the circular localization of skin sensations at the level of the spinal “station” of sensory nerves has been replaced by a unilateral localization of these sensations at the level of the visual thalamus.

An electrophysiological study of the action currents of tactile sensory nerves showed that the impulse that occurs when applying weak mechanical stimulation (touch) is characterized by a high frequency (up to 200 m in 1 sec), speed, discontinuity (up to 80 m in 1 sec) and the rapid onset of adaptation to the stimulus. The speed of transmission of tactile stimulation impulses into the cortex exceeds the transmission of pain impulses by approximately 8 times.

The nervous system regulates and coordinates the activities of all organs. It also ensures the interaction of the body with the environment. The nervous system includes the brain and spinal cord (central nervous system), which process information and generate commands to change the activity of organs, as well as nerves (peripheral nervous system), which connect the brain with organs.

What are nerves?

Nerves are bundles of fibers (nerve cell processes) surrounded by special sheaths. The number of nerve fibers in one nerve reaches tens and hundreds of thousands, so the diameter of the nerve varies from fractions of a millimeter to a centimeter. The length of the nerves and the number of their branches are determined by the structural features and development of the organs to which the nerves are directed.

From the spinal cord there are 31 pairs of spinal nerves (to the right and left sides of the body), which serve the organs, muscles and skin of the trunk and limbs. 12 pairs of cranial nerves depart from the brain, regulating the activity of mainly the organs of the head and neck. The longest of all cranial nerves, the vagus nerve, is involved in regulating the functioning of the organs of the thoracic and abdominal cavities. Cranial nerves have serial numbers and their own names. They originate primarily from the brain stem - there are the nuclei (nerve centers) of the cranial nerves. There are sensory, motor and mixed cranial nerves.

Sensory cranial nerves

Sensory nerves transmit information from the senses to the brain. These include the olfactory, optic and vestibulocochlear nerves.

Olfactory nerve
The olfactory nerves transmit information to the brain from receptor cells located in the mucous membrane of the nasal cavity. Thin threads of the nerve (15-20) penetrate into the cranial cavity, the olfactory bulbs lying on the lower surface of the frontal lobes of the cerebral hemispheres. This is where the olfactory tracts begin, along which information is sent to the subcortical centers and to the cerebral cortex. If the frontal region is damaged, smell disturbances may occur.

Optic nerve
The optic nerve is formed by processes of nerve cells in the retina that emerge near the posterior pole of the eyeball. Inside the skull, the fibers of the optic nerve cross and pass into the visual tract, which ends in the subcortical centers. Next, the pathways go to the higher center in the cortex of the occipital lobe of the hemispheres. At the site of the optic chiasm, only the nerve fibers coming from the inner halves of the retina cross, creating the conditions for binocular vision (receiving the same image in both eyes). When the optic nerve, optic chiasm or optic tract is damaged, visual impairment will vary, which makes it possible to diagnose their localization.

vestibulocochlear nerve
The vestibular-cochlear nerve consists of 2 parts: cochlear and vestibular. The first conducts impulses from the organ of hearing, the second - from the organ of balance. The hearing and balance receptors are located inside the temporal bone. Both parts of the nerve connect in the internal auditory canal, from there they enter the cranial cavity. In the brain, the pathways for auditory and vestibular information are different: the auditory center is located in the temporal lobe of the cerebral hemispheres, and the vestibular center is in the cerebellum. If the temporal bone is damaged, not only hearing loss and balance disorders are possible, but also impaired salivation and facial expressions, since next to the vestibulocochlear nerve in the internal auditory canal there is a nerve (facial) involved in the innervation of the salivary glands and facial muscles.

Motor cranial nerves

The motor cranial nerves carry commands to the muscles of the eyeball, tongue, and some neck muscles.

Oculomotor, trochlear and abducens nerves
The oculomotor, trochlear and abducens nerves penetrate from the cranial cavity into the orbit and provide all the variety of movements of the eyeballs and the muscle that lifts the upper eyelid. When the oculomotor nerve is damaged, divergent strabismus, drooping of the eyelid and dilation of the pupil are observed. Damage to the trochlear nerve results in a slanted position of the eyeballs and causes doubling of the objects in question. If the abducens nerve is damaged, internal strabismus develops.

Accessory and hypoglossal nerves
The accessory nerve supplies the muscles involved in movements of the head and neck. When it is damaged, torticollis is observed - a tilt of the head with a turn in the other direction. The hypoglossal nerve carries commands to the muscles of the tongue. When it is affected, the tongue deviates to the affected side, which affects the position of the larynx.

Mixed cranial nerves

The mixed cranial nerves include the trigeminal, facial, glossopharyngeal and vagus nerves.

Trigeminal nerve
The trigeminal nerve has three main branches: the ophthalmic, maxillary and mandibular nerves.
The optic nerve passes into the orbit and innervates its contents, the upper eyelid, the skin of the forehead and crown, the mucous membrane of the upper part of the nasal cavity and paranasal sinuses. The maxillary nerve is sensitive to the gums and teeth of the upper jaw, the mucous membrane of the palate, the nasal cavity and maxillary sinus, the skin of the nose and cheeks. The sensory fibers of the mandibular nerve are directed to the gums and teeth of the lower jaw, the mucous membrane of the tongue and cheeks, as well as to the skin of the chin and the lower part of the auricle. The motor branches of the mandibular nerve carry commands to the masticatory muscles. If the trigeminal nerve is damaged, disturbances in the sensitivity of the skin of the face and palate are observed, and paralysis of the masticatory muscles may develop.

Facial nerve
The facial nerve gets its name because its motor branches regulate the functioning of facial muscles. Sensory fibers of the facial nerve conduct taste stimulation from the anterior 2/3 of the tongue. Commands transmitted along the fibers of the facial nerve increase salivation and the production of tear fluid.

Glossopharyngeal nerve
The glossopharyngeal nerve innervates the mucous membrane of the posterior 1/3 of the tongue, the upper part of the pharynx and the tympanic cavity. The nerve contains a branch that carries information from the carotid arteries to the brain about the state of blood pressure and the chemical composition of the blood. The branches of the glossopharyngeal nerve, going to the muscles of the pharynx and the parotid salivary gland, cause increased salivation.

Nervus vagus
The vagus nerve is the longest of the cranial nerves. Its numerous branches are directed to the muscles of the pharynx and soft palate, the organs of the neck, the skin of the auricle, the heart, the respiratory and digestive organs, the kidneys, and the endocrine glands. The large length of the vagus nerve is explained by the fact that in the distant ancestors of humans, the organs innervated by it lay near the head and only in the process of evolution gradually moved back, stretching the nerve fibers.

In the neck, the vagus nerve passes in the area of ​​the carotid artery and internal jugular vein, then goes to the mucous membrane of the root of the tongue, larynx, pharynx and esophagus. Its motor fibers regulate the volume and pitch of the voice and the act of swallowing. A large number of branches of the vagus nerve extend to the heart. In the chest cavity, it passes along the wall of the esophagus and gives off branches to the esophagus, trachea, bronchi, lungs and heart, forming nerve plexuses near these organs. Under the influence of the vagus nerve, the heart slows down and weakens contractions, and the bronchi narrow.

Together with the esophagus, the vagus nerve passes through the diaphragm into the abdominal cavity, where it innervates the stomach, liver, spleen, pancreas, kidneys, small intestine and part of the colon. Under the influence of the vagus nerve, the secretion of the digestive glands and intestinal motility are activated; The adrenal glands reduce the production of hormones. The vagus nerve is involved in vomiting. Damage to the vagus nerve, depending on the location, can lead to dysfunction of the gastrointestinal tract (spastic conditions), cardiac dysfunction, laryngeal function (loss of sonority of the voice) and breathing.

Vagotomy
Vagotomy reduces the acidity of gastric juice, because it blocks the conduction
to the gastric mucosa of nerve impulses that increase secretion
acids by parietal cells of the mucous membrane. With stem
Vagotomies cross the entire vagus nerve. With selective
Vagotomies only cross certain branches of the nerve.

Cranial nerves(cranial nerves, lat. nervi craniales) - twelve pairs of nerves extending from. They are designated by Roman numerals in the order in which they are located, each of them has its own name.

In Russian-language sources, the term cranial nerves is often used. According to the latest anatomical terminology adopted in Sao Paulo in 1997, the term is designated as lat. Nervi craniales(cranial nerves). In the 6th edition of Sinelnikov’s atlas of human anatomy, monographs dedicated to human anatomy, the term is unified under the international anatomical classification. At the same time, the frequency of use of the combination “cranial nerves” is evidenced by the first phrase of the corresponding article in the Great Soviet Encyclopedia:

Cranial nerves, more correctly cranial

List of nerves

• I pair - (lat. nervus olfactorius)
• II pair - optic nerve (lat. nervus opticus)
• III pair - oculomotor nerve (lat. nervus oculomotorius)
• IV pair - trochlear nerve (lat. nervus trochlearis)
• V pair - trigeminal nerve (lat. nervus trigeminus)
• VI pair - abducens nerve (lat. nervus abducens)
• VII pair - facial nerve (lat. nervus facialis)
• VIII pair - vestibulocochlear nerve (lat. nervus vestibulocochlearis)
• IX pair - glossopharyngeal nerve (lat. nervus glossopharyngeus)
• X pair - vagus nerve (lat. nervus vagus)
• XI pair - accessory nerve (lat. nervus accessorius)
• XII pair - hypoglossal nerve (lat. nervus hypoglossus)

Mnemonic rules

Onegin Knew Where Tatyana Was, He Loved to Listen to the Language of his Infinitely Dear Friend.

Onegin Knew Where Tatyana Was, He Was Flying Like a Bullet, His Tongue Lolling Out to His Waist.

To memorize a pair of cranial nerves in Latin: About Oryasin, the Donkey sharpens the axe, And the Fakir, having kicked out the Guests, wants to howl like a Shark.

Smell, look, move your eyes, remove the trigeminal block, face, tongue and throat. Don't fornicate in vain. Add under tongues.

I smelled, I saw, I moved my eye, and the trigeminal block abducted. Face and hearing, and glossopharynx, wandering, walked with an additional gait, finding all the nerves under the tongue.

Development of cranial nerves in embryogenesis

The olfactory and optic nerves develop from protrusions of the anterior medullary bladder and consist of axons of neurons that are located in the mucous membrane of the nasal cavity (organ) or in the retina of the eye. The remaining sensory nerves are formed by the eviction of young nerve cells from the developing brain, the processes of which form sensory nerves or sensory (afferent) fibers of mixed nerves. Motor cranial nerves are formed from motor (efferent) nerve fibers, which are processes of cells of the motor nuclei located in the brain stem. The formation of cranial nerves in phylogenesis is associated with the development of visceral arches and their derivatives, and the reduction of somites in the head region.

Where cranial nerves exit the brain

It is impossible to say about the first (olfactory) nerve that it “comes out” of the brain, since it carries only afferent (sensitive) information. The olfactory nerve is the processes of the olfactory cells of the nasal mucosa, collected in olfactory filaments. The olfactory filaments reach the olfactory bulb through the openings of the cribriform plate of the ethmoid bone.

It is also impossible to say about the second (optic) nerve that it “comes out” of the brain, for the same reason. It originates from the optic nerve head, located at the posterior pole of the eye. The optic nerve passes into the cranial cavity through the optic canal formed by the lesser wing of the sphenoid bone. In the cranial cavity, the optic nerves of both eyes form a chiasm, and only part of the fibers intersect. Further, the fiber paths are called the “optic tract”.

The third (oculomotor) nerve exits from the ventral (“facial”) side of the trunk next to the interpeduncular fossa (fossa interpeduncularis).

The IV (trochlear) nerve is the only one emerging from the dorsal (“dorsal”) side of the trunk, from the upper edge, bending, exiting to the ventral side from under the cerebral peduncles.

The V (trigeminal) nerve exits the ventral side of the pons.

Nerves VI through VIII also exit on the ventral side of the brain stem between and the pons, from the edges to the center in a row, with VII and VIII lying close to each other at the “angle” of the medulla oblongata, and VI (abducens) at the level of the anterolateral sulcus.

Nerves IX to XII emerge from the medulla oblongata on the ventral side. The XI (accessory) nerve stands somewhat apart - it combines, in addition to the head part, some roots. Nerves IX to XI emerge from the lateral surface of the medulla, from bottom to top in a row.

The XII (hypoglossal) nerve emerges from the anterolateral groove (lat. sulcus ventrolateralis).

Cranial nerve nuclei

Functions of cranial nerves

Olfactory nerve (olfactory nerves) (lat. nervi olfactorii) is the first of the cranial nerves responsible for olfactory sensitivity.

Optic nerve(lat. Nervus opticus) - the second pair of cranial nerves through which visual stimuli perceived by the sensitive cells of the retina are transmitted to the brain.

Oculomotor nerve(lat. nervus oculomotorius) - III pair of cranial nerves, responsible for the movement of the eyeball, raising the eyelid, and the reaction of the pupils to light.

Trochlear nerve lat. nervus trochlearis- IV pair of cranial nerves, which innervates the superior oblique muscle (lat. m.obliquus superior), which turns the eyeball outward and downward.

V (trigeminal) nerve is mixed. Its three branches (ramus ophthalmicus - V1, ramus maxillaris - V2, ramus mandibularis - V3) through the Gasserian ganglion (ganglion trigeminale) carry information from the upper, middle and lower thirds of the face, respectively. Each branch carries information from the muscles, skin and pain receptors of each third of the face. In the Gaserian ganglion, information is sorted by type, and information from the muscles of the entire face goes to the sensitive nucleus of the trigeminal nerve, located mostly in (partially enters the pons); cutaneous information from the entire face goes to the “main nucleus” (nucleus pontinus nervi trigemini), located in the pons; and pain sensitivity is in the nucleus spinalis nervi trigemini, coming from the bridge through the medulla oblongata to the spinal cord.

The trigeminal nerve also belongs to the motor nucleus (lat. nucleus motorius nervi trigemini), located in the bridge and responsible for the innervation of the masticatory muscles.

Abducens nerve(lat. nervus abducens) - VI pair of cranial nerves, which innervates the lateral rectus muscle (lat. m. rectus lateralis) is responsible for abduction of the eyeball.

Facial nerve(lat. nervus facialis), the seventh (VII) of the twelve cranial nerves, exits the brain between the pons and the medulla oblongata. The facial nerve innervates the facial muscles. Also included in the facial nerve is the intermediate nerve, which is responsible for the innervation of the lacrimal gland, the stapedius muscle and the taste sensitivity of the two anterior third tongues.

vestibulocochlear nerve(lat. nervus vestibulocochlearis) - a nerve of special sensitivity responsible for the transmission of auditory impulses and impulses emanating from the vestibular part of the inner ear.

Glossopharyngeal nerve(lat. nervus glossopharyngeus) - IX pair of cranial nerves. Is mixed. Provides:

• motor innervation of the stylopharyngeal muscle (lat. m. stylohyoideus), elevating the pharynx
• innervation of the parotid gland (lat. glandula parotis) providing its secretory function
• general sensitivity of the pharynx, tonsils, soft palate, Eustachian tube, tympanic cavity
• taste sensitivity of the posterior third of the tongue.

Nervus vagus(lat. n.vagus) - X pair of cranial nerves. Is mixed. Provides:

• motor innervation of the muscles of the soft palate, pharynx, larynx, as well as striated muscles of the esophagus
• parasympathetic innervation of the smooth muscles of the lungs, esophagus, stomach and intestines (up to the splenic flexure of the colon), as well as the muscles of the heart. Also affects the secretion of the glands of the stomach and pancreas
• sensitive innervation of the mucous membrane of the lower part of the pharynx and larynx, the skin behind the ear and part of the external auditory canal, the eardrum and the dura mater of the posterior cranial fossa.

Accessory nerve(lat. nervus accessorius) - XI pair of cranial nerves. Contains motor nerve fibers that innervate the muscles responsible for turning the head, raising the shoulder and adducting the scapula to the spine.

Hypoglossal nerve(lat. nervus hypoglossus) - XII pair of cranial nerves. Responsible for the movement of the tongue.