Which cranial nerve is mixed in function? Damage to cranial nerves

Olfactory nerve(n. olfactorius).

Olfactory receptor cells are scattered in the epithelium of the mucous membrane of the olfactory region of the nasal cavity. The thin central processes of these cells are collected into olfactory filaments, which are the olfactory nerve itself. From the nasal cavity, the nerve enters the cranial cavity through the openings of the ethmoid bone and ends in the olfactory bulb. From the cells of the olfactory bulb, the central olfactory pathways begin to the cortical zone of the olfactory analyzer in the temporal lobe of the brain.

Bilateral complete loss of smell (anosmia) or its decrease (hyposmia) is often the result of a disease of the nose or is congenital (sometimes in this case combined with certain endocrine disorders). Unilateral disturbances of smell are mainly associated with a pathological process in the anterior cranial fossa (tumor, hematoma, traumatic brain injury, etc.). Unusual paroxysmal olfactory sensations (parosmia), often some vague unpleasant odor, are harbingers of an epileptic seizure caused by irritation of the temporal lobe of the brain. Irritation of the temporal lobe of the brain can cause a variety of olfactory hallucinations.

Research methodology. The study of smell is carried out using a special set of aromatic substances (camphor, mint, valerian, pine extract, eucalyptus oil). The subject, with his eyes closed and one half of his nose pinched, is presented with odorous substances and asked to say what smell he smells and whether he perceives the smells equally well in each nostril separately. Do not use substances with strong odors (ammonia, acetic acid), because in this case, irritation of the endings of the trigeminal nerve occurs, so the results of the study will be inaccurate.

Symptoms of the lesion. They vary depending on the level of damage to the olfactory nerve. The main ones are loss of smell - anosmia, decreased sense of smell - hyposmia, increased sense of smell - hyperosmia, perversion of smell - dysosmia, olfactory hallucinations. For the clinic, a unilateral decrease or loss of smell is mainly important, because bilateral hypo- or anosmia is caused by symptoms of acute or chronic rhinitis.

Hypoosmia or anosmia occurs when the olfactory pathways up to the olfactory triangle are affected, i.e. at the level of the first and second neurons. Due to the fact that third neurons have cortical representation on both their own and the opposite side, damage to the cortex in the olfactory projection field does not cause loss of smell. However, in cases of irritation of the cortex of this area, sensations of non-existent odors may occur.

The proximity of the olfactory filaments, olfactory bulb and olfactory tract to the base of the skull leads to the fact that during pathological processes at the base of the skull and brain, the sense of smell is also impaired.

Optic nerve(n. opticus).

It is formed by the axons of neurons of the ganglion layer of the retina, which, through the cribriform plate of the sclera, exit the eyeball through a single trunk of the optic nerve into the cranial cavity. At the base of the brain in the area of ​​the sella turcica, the fibers of the optic nerves converge on both sides, forming the optic chiasm and optic tracts. The latter continue to the external geniculate body and the thalamic cushion, then the central visual pathway goes to the cerebral cortex (occipital lobe). Incomplete decussation of the fibers of the optic nerves causes the presence in the right optic tract of fibers from the right halves, and in the left optic tract - from the left halves of the retinas of both eyes.

Symptoms of the lesion.

When the conduction of the optic nerve is completely interrupted, blindness occurs on the side of the damage with the loss of the direct reaction of the pupil to light. When only part of the optic nerve fibers are damaged, focal loss of the visual field (scotomy) occurs. When the chiasm is completely destroyed, bilateral blindness develops. However, in many intracranial processes, damage to the chiasm can be partial - loss of the outer or inner halves of the visual fields develops (heteronymous hemianopsia). With unilateral damage to the optic tracts and overlying visual pathways, unilateral loss of visual fields on the opposite side occurs (homonymous hemianopsia).

Damage to the optic nerve can be inflammatory, congestive and dystrophic in nature; detected by ophthalmoscopy. The causes of optic neuritis can be meningitis, encephalitis, arachnoiditis, multiple sclerosis, influenza, inflammation of the paranasal sinuses, etc. They are manifested by a decrease in acuity and a narrowing of the field of vision, which is not corrected by the use of glasses. A congested optic nerve papilla is a symptom of increased intracranial pressure or impaired venous outflow from the orbit. As congestion progresses, visual acuity decreases and blindness may occur. Optic nerve atrophy can be primary (with tabes dorsalis, multiple sclerosis, optic nerve injury) or secondary (as a result of neuritis or congestive nipple); There is a sharp decrease in visual acuity up to complete blindness, and a narrowing of the field of vision.

Ocular fundus– part of the inner surface of the eyeball visible during ophthalmoscopic examination (optic disc, retina and choroid). The optic disc stands out against the red background of the fundus as a rounded formation with clear boundaries and a pale pink color. In the posterior pole of the eye there is the most sensitive area of ​​the retina - the so-called macula macula, which has the shape of a horizontal oval of a yellowish tint. The macula consists of cones, which provide daytime vision and are involved in the accurate perception of the shape, color and details of an object. As you move away from the macula, the number of cones decreases and the number of rods increases. The rods have very high light sensitivity and provide the perception of objects at dusk or at night.

Research methodology. Find out whether there are complaints about decreased visual acuity, loss of the visual field, the appearance of sparks, dark spots, flies, etc. before the eyes.

Visual acuity is examined using special tables on which letters are depicted in rows. Moreover, each bottom row is smaller than the previous one. On the side of each row there is a number indicating from what distance the letters of this row should be read with normal visual acuity.

Visual fields are examined using the perimeter. It is often necessary to use an approximate method for measuring visual fields. To do this, a person sits with his back to the light source, closes one eye, but without pressing on the eyeball. The examiner sits in front of the patient, asks the patient to fix the gaze on some point in front of him, moves the hammer from the patient’s ear in a circle to the bridge of the nose, and asks the patient to tell him when he sees him. The external field of view is usually 90 degrees. The internal, upper and lower visual fields are examined in a similar way and are 60, 60, 70 deg. respectively.

Color perception is studied using special polychromatic tables, on which numbers, figures, etc. are depicted in spots of different colors.

The fundus is examined using an ophthalmoscope and a photo-ophthalmoscope, which allows obtaining both black-and-white and color photographs of the fundus.

Oculomotor nerve. (n. oculomotorius).

Innervates the external muscles of the eye (with the exception of the external rectus and superior oblique), the muscle that lifts the upper eyelid, the muscle that constricts the pupil, the ciliary muscle, which regulates the configuration of the lens, which allows the eye to adapt to near and far vision.

System III pair consists of two neurons. The central one is represented by the cells of the cortex of the precentral gyrus, the axons of which, as part of the corticonuclear tract, approach the nuclei of the oculomotor nerve on both its own and the opposite side.

A wide variety of functions performed by the third pair is carried out using 5 nuclei for the innervation of the right and left eyes. They are located in the cerebral peduncles at the level of the superior colliculi of the midbrain roof and are peripheral neurons of the oculomotor nerve. From the two magnocellular nuclei, the fibers go to the external muscles of the eye on their own and partially the opposite side. The fibers innervating the muscle that lifts the upper eyelid come from the nucleus of the same and opposite side. From two small cell accessory nuclei, parasympathetic fibers are directed to the muscle constrictor pupil, on its own and the opposite side. This ensures a friendly reaction of the pupils to light, as well as a reaction to convergence: constriction of the pupil while simultaneously contracting the rectus intrinsic muscles of both eyes. From the posterior central unpaired nucleus, which is also parasympathetic, the fibers are directed to the ciliary muscle, which regulates the degree of convexity of the lens. When looking at objects located near the eye, the convexity of the lens increases and at the same time the pupil narrows, which ensures a clear image on the retina. If accommodation is impaired, a person loses the ability to see clear outlines of objects at different distances from the eye.

The fibers of the peripheral motor neuron of the oculomotor nerve begin from the cells of the above nuclei and emerge from the cerebral peduncles on their medial surface, then pierce the dura mater and then follow in the outer wall of the cavernous sinus. From the skull, the oculomotor nerve exits through the superior orbital fissure and enters the orbit.

Symptoms of defeat.

Disruption of the innervation of individual external muscles of the eye is caused by damage to one or another part of the magnocellular nucleus; paralysis of all muscles of the eye is associated with damage to the nerve trunk itself. An important clinical sign that helps to distinguish between damage to the nucleus and the nerve itself is the state of innervation of the muscle that lifts the upper eyelid and the internal rectus muscle of the eye. The cells from which the fibers go to the muscle that lifts the upper eyelid are located deeper than the rest of the cells of the nucleus, and the fibers going to this muscle in the nerve itself are located most superficially. The fibers innervating the internal rectus muscle of the eye run in the trunk of the opposite nerve. Therefore, when the trunk of the oculomotor nerve is damaged, the first to be affected are the fibers innervating the muscle that lifts the upper eyelid. Weakness of this muscle or complete paralysis develops, and the patient can either only partially open the eye or not open it at all. With a nuclear lesion, the muscle that lifts the upper eyelid is one of the last to be affected. When the core is hit, “the drama ends with the curtain falling.” In the case of a nuclear lesion, all external muscles on the affected side are affected, with the exception of the internal rectus muscle, which is isolated in isolation on the opposite side. As a result of this, the eyeball on the opposite side will be turned outward due to the external rectus muscle of the eye - divergent strabismus. If only the magnocellular nucleus is affected, the external muscles of the eye are affected - external ophthalmoplegia. Because when the nucleus is damaged, the process is localized in the cerebral peduncle, then the pyramidal tract and fibers of the spinothalamic tract are often involved in the pathological process, alternating Weber syndrome occurs, i.e. lesion of the third pair on one side and hemiplegia on the opposite side.

The nerves that leave and enter the brain are called cranial nerves. Their distribution and brief characteristics are discussed separately in the next article.

Types of nerves and pathologies

There are several types of nerves:

• motor;
• mixed;
• sensitive.

The neurology of motor cranial nerves, both sensory and mixed, has pronounced manifestations that specialists can easily diagnose. In addition to isolated damage to individual nerves, those that simultaneously belong to different groups can also be affected. Thanks to knowledge of their location and functions, it is possible not only to understand which nerve is damaged, but also to localize the affected area. This becomes achievable through special techniques using high-tech equipment. For example, in ophthalmological practice, using modern technology, it is possible to find out the condition of the fundus, optic nerve, determine the field of vision and areas of loss.

Carotid and verbal angiography reveal good values. But more detailed information can be obtained using computed tomography. With it you can see individual nerve trunks and identify tumors and other changes in the auditory, optic and other nerves.

It became possible to study the trigeminal and auditory nerves thanks to the method of cortical somatosensory potentials. Also in this case, audiography and nystagmography are used.

The development of electromyography has expanded the ability to obtain more detailed information about cranial nerves. Now you can study, for example, the reflex blink response, spontaneous muscle activity during facial expressions and chewing, the palate, and so on.

Let us dwell in more detail on each of the pairs of these nerves. There are a total of 12 pairs of cranial nerves. A table containing all of them is indicated at the end of the article. For now, let's look at each of the pairs separately.

1 pair. Description

This includes the sensitive group. In this case, receptor cells are scattered in the epithelium of the nasal cavity in the olfactory part. Thin nerve cell processes are concentrated in the olfactory filaments, which are the olfactory nerves. From the nasal nerve it enters the cranial cavity through the openings of the plate and ends in the bulb, where the central olfactory pathways originate.

2 pair. Optic nerve

This pair includes the optic nerve, which belongs to the sensitive group. The axons of neurons here exit through the cribriform plate from the eyeball with one trunk, which enters the cranial cavity. At the base of the brain, the fibers of these nerves on both sides converge and create the optic chiasm and tracts. The tracts go to the geniculate body and the thalamus of the pillow, after which the central visual pathway is directed to the occipital lobe of the brain.

3 pair. Motor nerve

The oculomotor (motor) nerve, created by fibers, passes from those nerves that are located in the gray matter under the aqueduct of the brain. To the base it passes between the legs, after which it enters the orbit and innervates the eye muscles (except for the superior oblique and external rectus, other cranial nerves are responsible for their innervation, 12 pairs, the table indicating which clearly illustrates all of them together). This occurs due to the parasympathetic fibers contained in the nerve.

4 pair. Trochlear nerve

This pair includes (motor), originating from the nucleus under the aqueduct of the brain and emerging to the surface in the area of ​​the medullary velum. In this part, a cross is obtained, going around the leg and penetration into the orbit. This pair innervates the superior oblique muscle.

5th pair of 12 pairs of cranial nerves

The table continues with the trigeminal nerve, which is already classified as mixed. Its trunk contains sensory and motor nuclei, and at the base there are their roots and branches. Sensitive fibers originate from the cells of the trigeminal ganglion, whose dendrites create peripheral branches that innervate the skin of the scalp in front, as well as the face, gums with teeth, ocular conjunctiva, mucous membranes of the nose, mouth, and tongue.
Motor fibers (from the trigeminal nerve root) connect to the mandibular nerve branch, pass through and innervate the masticatory muscles.

6 pair. Abducens nerve

The next pair included in the 12 pairs of cranial nerves (the table classifies it as a group of motor nerves) includes It starts from the cell nuclei in the pons, penetrates the base and moves forward to the orbital fissure from above and further to the orbit. It innervates the rectus eye muscle (external).

7 pair. Facial nerve

This pair consists of the facial nerve (motor), created from the cellular processes of the motor nucleus. The fibers begin their journey in the trunk at the bottom of the fourth ventricle, pass around the nucleus of the fourth nerve, descend to the base and exit into the cerebellopontine angle. Then it moves to the auditory opening, into the facial nerve canal. After the parotid gland, it is divided into branches that innervate the facial muscles and muscles, as well as a number of others. In addition, one branch extending from its trunk innervates the muscle located in the middle ear.

8 pair. Auditory nerve

The eighth pair of 12 pairs of cranial nerves (the table ranks it among the sensory nerves) consists of the auditory, or vestibular-cochlear nerve, which includes two parts: vestibular and cochlear. The cochlear part consists of dendrites and axons of the spiral ganglion located in the bony cochlea. And the other part departs from the vestibular node at the bottom of the auditory canal. The nerve on both sides connects in the ear canal to form the auditory nerve.

The fibers of the vestibular part end in those nuclei that are located in the rhomboid fossa, and the cochlear part ends in the cochlear nuclei of the pons.

9 pair. Glossopharyngeal nerve

The table of cranial nerves continues with the ninth pair, which is represented by sensory, motor, secretory and taste fibers. There are close connections with the vagus and intermediate nerves. Many nuclei of the nerve in question are located in the medulla oblongata. They are shared with the tenth and twelfth pairs.

The nerve fibers of the pair unite into a trunk that leaves the cranial cavity. For the posterior third of the palate and tongue it is a taste and sensory nerve, for the inner ear and pharynx it is sensitive, for the pharynx it is motor, for the parotid gland it is secretory.

10 pair. Nervus vagus

Next, the table of cranial nerves continues with a pair consisting of the vagus nerve, which is endowed with different functions. The trunk begins from the roots in the medulla oblongata. Coming out of the cranial cavity, the nerve innervates the striated muscles in the pharynx, as well as in the larynx, palate, trachea, bronchi and digestive organs.

Sensitive fibers innervate the occipital region of the brain, the external auditory canal, and other organs. Secretory fibers are directed to the stomach and pancreas, vasomotor fibers to the vessels, parasympathetic fibers to the heart.

11 pair. Description of the accessory nerve

The accessory nerve represented in this pair consists of an upper and lower section. The first comes from the motor nucleus of the medulla oblongata, and the second from the nucleus in the horns of the spinal cord. The roots are connected to each other and leave the skull along with the tenth pair. Some of them go to this vagus nerve.

It innervates the muscles - sternocleidomastoid and trapezius.

12 pair

The summary table of cranial nerves ends with a pair with Its nucleus is located at the bottom of the medulla oblongata. Coming out of the skull, it innervates the lingual muscles.

These are approximate diagrams of 12 pairs of cranial nerves. Let's summarize the above.

Look at the list of cranial nerves, 12 pairs. The table is as follows.

Conclusion

This is the structure and function of these nerves. Each couple plays its most important role. Each nerve is a part of a huge system and depends on it in the same way as the entire system - on the functioning of individual nerves.

There are 13 pairs of cranial nerves (Fig. 222): zero pair - terminal nerve n. terminalis); I - olfactory (n. olfactorius); II - visual (n. opticus); III - oculomotor (n. oculomotorius); IV - block, (n. trochlearis); V- trigeminal (n. trigeminus); VI - abducens (n. abducens); VII - facial (n. facialis); VIII - vestibulocochlearis (n. vestibulocochlearis); IX- glossopharyngeus (n. glossopharyngeus); X- wandering (n. vagus); XI - additional (n. accessorius); XII - sublingual (n. hypoglossus).

DEVELOPMENT AND PRINCIPLES OF STRUCTURE OF CRANIAL NERVES

The olfactory and optic nerves are specific nerves of the sensory organs that develop from the forebrain and are its outgrowths. The remaining cranial nerves differentiated from the spinal nerves and therefore are fundamentally similar in structure to them. The differentiation and transformation of primary spinal nerves into cranial nerves is associated with the development of sensory organs and gill arches with their associated muscles, as well as with the reduction of myotomes in the head region (Fig. 223). However, none of the cranial nerves corresponds completely to the spinal nerves, since they are not composed of anterior and posterior roots, but only of one anterior or posterior. Cranial nerves III, IV, VI pairs correspond to the anterior roots. Their nuclei are located ventrally, they innervate the muscles that developed from the 3 anterior somites of the head. The remaining anterior roots are reduced.

Other cranial nerves V, VII, VIII, X, XI and XII pairs can be considered as homologues of the dorsal roots. These nerves are associated with muscles that, during evolution, originated from the muscles of the gill apparatus and developed in embryogenesis from the lateral plates of the mesoderm. In lower vertebrates, the nerves form two branches: anterior motor and posterior sensory.

Rice. 222. Cranial nerves:

a - places of exit from the brain; b - places of exit from the skull;

1 - olfactory tract; 2 - optic nerve; 3 - oculomotor nerve; 4 - trochlear nerve; 5 - trigeminal nerve; 6 - abducens nerve; 7 - facial nerve; 8 - vestibulocochlear nerve; 9 - oculomotor nerve; 10 - vagus nerve; 11 - accessory nerve; 12 - hypoglossal nerve; 13 - spinal cord; 14 - medulla oblongata; 15 - bridge; 16 - midbrain; 17 - diencephalon; 18 - olfactory bulb

In higher vertebrates, the posterior branch of the cranial nerves is usually reduced.

The X and XII cranial nerves have a complex origin, since during evolution they are formed by the fusion of several spinal nerves. Due to the assimilation of metameres of the body by the occipital region of the head, part of the spinal nerves moves cranially and enters the region of the medulla oblongata. Subsequently, the IX and XI cranial nerves are separated from a common source - the primary vagus nerve; they are, as it were, its branches (Table 14).

Rice. 222. Ending

Table 14. Correlation of somites of the head, branchial arches and cranial nerves with

their roots

Rice. 223.Cranial nerves of a human embryo. The gill arches are indicated by Arabic numerals, the nerves by Roman numerals:

1 - preauricular somites; 2 - postauricular somites; 3 - accessory nerve associated with the mesenchyme of the 5th branchial arch; 4 - parasympathetic and visceral sensory fibers of the vagus nerve to the anterior and middle primary gut; 5 - cardiac protrusion; 6 - tympanic nerve (visceral sensory fibers to the middle ear and parasympathetic fibers to the parotid salivary gland); 7 - taste fibers to the anterior 2/3 of the tongue and parasympathetic fibers to the salivary glands; 8 - olfactory placode; 9 - mesenchyme of the head; 10 - submandibular node; 11 - optic cup; 12 - lens rudiment; 13 - pterygopalatine node; 14 - ciliary node; 15 - ear node; 16 - optic nerve (sensitive to the eye socket, nose and front of the head)

Rice. 224. Functional features of the cranial nerves: I - olfactory nerve; II - optic nerve; III - oculomotor: motor (external muscles of the eye, ciliary muscle and muscle that constricts the pupil); IV - trochlear nerve: motor (superior oblique muscle of the eye); V - trigeminal nerve: sensitive (face, paranasal sinuses, teeth); motor (muscles of mastication); VI - abducens nerve: motor (lateral rectus muscle of the eye); VII - facial nerve: motor (facial muscles); Intermediate nerve: sensory (taste sensitivity); efferent (parasympathetic) (submandibular and sublingual salivary glands); VIII - vestibulocochlear nerve: sensitive (cochlea and vestibule); IX - glossopharyngeal nerve: sensitive (posterior third of the tongue, tonsil, pharynx, middle ear); motor (stylopharyngeal muscle); efferent (parasympathetic) (parotid salivary gland); X - vagus nerve: sensitive (heart, larynx, trachea, bronchi, lungs, pharynx, gastrointestinal tract, outer ear); motor (parasympathetic) (same area); XI - accessory nerve: motor (sternocleidomastoid and trapezius muscles); XII - hypoglossal nerve: motor (tongue muscles)

According to their functional affiliation, the cranial nerves are distributed as follows (Fig. 224). I, II and VIII pairs belong to the sensory nerves; III, IV, VI, XI and XII pairs are motor and contain fibers for striated muscles; Pairs V, VII, IX and X are mixed nerves, as they contain both motor and sensory fibers. At the same time, parasympathetic fibers pass through the III, VII, IX and X nerves, innervating smooth muscles and glandular epithelium. Along the cranial nerves and their branches, sympathetic fibers can join them, which significantly complicates the anatomy of the innervation pathways of the head and neck organs.

The nuclei of the cranial nerves are located predominantly in the rhombencephalon (V, VI, VII, VIII, IX, X, XI, XII pairs); in the tegmentum of the cerebral peduncles, in the midbrain, there are nuclei of the III and IV pairs, as well as one nucleus of the V pair; I and II pairs of cranial nerves are connected to the diencephalon (Fig. 225).

0 pair - terminal nerves

Terminal nerve (zero pair)(n. terminalis)- This is a pair of small nerves that are closely adjacent to the olfactory nerves. They were first discovered in lower vertebrates, but their presence has been shown in human fetuses and in adult humans. They contain many unmyelinated fibers and associated small groups of bipolar and multipolar nerve cells. Each nerve passes along the medial side of the olfactory tract, their branches pierce the cribriform plate of the ethmoid bone and branch in the mucous membrane of the nasal cavity. Centrally, the nerve is connected to the brain near the anterior perforated space and the septum pellucidum. Its function is unknown, but it is thought to be the head of the sympathetic nervous system, which extends to the blood vessels and glands of the nasal mucosa. There is also an opinion that this nerve is specialized for the perception of pheromones.

I pair - olfactory nerves

Olfactory nerve(n. olfactorius) educated 15-20 olfactory filaments (fila olfactoria), which consist of nerve fibers - processes of olfactory cells located in the mucous membrane of the upper part of the nasal cavity (Fig. 226). Olfactory threads

Rice. 225.Nuclei of cranial nerves in the brain stem, posterior view: 1 - oculomotor nerve; 2 - red core; 3 - motor nucleus of the oculomotor nerve; 4 - accessory autonomous nucleus of the oculomotor nerve; 5 - motor nucleus of the trochlear nerve; 6 - trochlear nerve; 7 - motor nucleus of the trigeminal nerve; 8, 30 - trigeminal nerve and ganglion; 9 - abducens nerve; 10 - motor nucleus of the facial nerve; 11 - knee of the facial nerve; 12 - upper and lower salivary nuclei; 13, 24 - glossopharyngeal nerve; 14, 23 - vagus nerve; 15 - accessory nerve; 16 - double core; 17, 20 - dorsal nucleus of the vagus nerve; 18 - nucleus of the hypoglossal nerve; 19 - spinal nucleus of the accessory nerve; 21 - core of a single bundle; 22 - spinal tract of the trigeminal nerve; 25 - nuclei of the vestibular nerve; 26 - nuclei of the cochlear nerve; 27 - vestibulocochlear nerve; 28 - facial nerve and knee node; 29 - main sensory nucleus of the trigeminal nerve; 31 - mesencephalic nucleus of the trigeminal nerve

Rice. 226. Olfactory nerve (diagram):

I - subcallosal area; 2 - septal field; 3 - anterior commissure; 4 - medial olfactory stripe; 5 - parahippocampal gyrus; 6 - dentate gyrus; 7 - fimbriae of the hippocampus; 8 - hook; 9 - amygdala; 10 - anterior perforated substance; 11 - lateral olfactory stripe; 12 - olfactory triangle; 13 - olfactory tract; 14 - cribriform plate of the ethmoid bone; 15 - olfactory bulb; 16 - olfactory nerve; 17 - olfactory cells; 18 - mucous membrane of the olfactory region

enter the cranial cavity through an opening in the cribriform plate and end at the olfactory bulbs, which continue into olfactory tract (tractus olfactorius)(see Fig. 222).

IIpair - optic nerves

Optic nerve(n. opticus) consists of nerve fibers formed by processes of multipolar nerve cells of the retina of the eyeball (Fig. 227). The optic nerve is formed on the posterior hemisphere of the eyeball and passes through the orbit to the optic canal, from where it exits into the cranial cavity. Here, in the pre-cross sulcus, both optic nerves connect, forming optic chiasm (chiasma opticum). The continuation of the visual pathways is called the optic tract (tractus opticus). At the optic chiasm, the medial group of nerve fibers of each nerve passes into the optic tract of the opposite side, and the lateral group continues into the corresponding optic tract. The visual tracts reach the subcortical visual centers (see Fig. 222).

Rice. 227. Optic nerve (diagram).

The visual fields of each eye are superimposed on one another; the dark circle in the center corresponds to the yellow spot; each quadrant has its own color: 1 - projection on the retina of the right eye; 2 - optic nerves; 3 - visual chiasm; 4 - projection onto the right geniculate body; 5 - visual tracts; 6, 12 - visual radiance; 7 - lateral geniculate bodies; 8 - projection onto the cortex of the right occipital lobe; 9 - calcarine groove; 10 - projection onto the cortex of the left occipital lobe; 11 - projection onto the left geniculate body; 13 - projection onto the retina of the left eye

III pair - oculomotor nerves

Oculomotor nerve(n. oculomotorius) mainly motor, arises in the motor nucleus (nucleus nervi oculomotorii) midbrain and visceral autonomous accessory nuclei (nuclei visceralis accessorii n. oculomotorii). It exits at the base of the brain at the medial edge of the cerebral peduncle and goes forward in the upper wall of the cavernous sinus to the superior orbital fissure, through which it enters the orbit and divides into upper branch (r. superior) - to the superior rectus muscle and the muscle that lifts the eyelid, and the inferior branch (r. inferior) - to the medial and inferior rectus and inferior oblique muscles (Fig. 228). A branch departs from the lower branch to the ciliary ganglion, which is its parasympathetic root.

Rice. 228. Oculomotor nerve, lateral view: 1 - ciliary ganglion; 2 - nasociliary root of the ciliary node; 3 - superior branch of the oculomotor nerve; 4 - nasociliary nerve; 5 - optic nerve; 6 - oculomotor nerve; 7 - trochlear nerve; 8 - accessory nucleus of the oculomotor nerve; 9 - motor nucleus of the oculomotor nerve; 10 - nucleus of the trochlear nerve; 11 - abducens nerve; 12 - lateral rectus muscle of the eye; 13 - lower branch of the oculomotor nerve; 14 - medial rectus muscle of the eye; 15 - inferior rectus muscle of the eye; 16 - oculomotor root of the ciliary ganglion; 17 - inferior oblique muscle of the eye; 18 - ciliary muscle; 19 - pupillary dilator, 20 - pupillary sphincter; 21 - superior rectus muscle of the eye; 22 - short ciliary nerves; 23 - long ciliary nerve

IVpair - trochlear nerves

Trochlear nerve(n. trochlearis) motor, originates in the motor nucleus (nucleus n. trochlearis), located in the midbrain at the level of the inferior colliculus. It extends to the base of the brain outward from the pons and continues forward in the outer wall of the cavernous sinus. It flows into the orbit through the superior orbital fissure and branches into the superior oblique muscle (Fig. 229).

Vpair - trigeminal nerves

Trigeminal nerve(n. trigeminus) is mixed and contains motor and sensory nerve fibers. Innervates the muscles of mastication, the skin of the face and anterior part of the head, the dura mater of the brain, as well as the mucous membranes of the nasal and oral cavities, and teeth.

The trigeminal nerve has a complex structure. It distinguishes

(Fig. 230, 231):

1) nuclei (one motor and three sensitive);

2) sensitive and motor roots;

3) trigeminal ganglion on the sensitive root;

4) 3 main branches of the trigeminal nerve: ophthalmic, maxillary And mandibular nerves.

Sensitive nerve cells, the peripheral processes of which form the sensory branches of the trigeminal nerve, are located in trigeminal ganglion, ganglion trigeminale. The trigeminal ganglion lies on trigeminal depression, inpressio trigeminalis, anterior surface of the pyramid of the temporal bone in trigeminal cavity (cavum trigeminale), formed by the dura mater. The node is flat, semilunar in shape, length (frontal size) 9-24 mm and width (sagittal size) 3-7 mm. In people with a brachycephalic skull, the nodes are large, in the form of a straight line, while in dolichocephals they are small, in the form of an open circle.

The cells of the trigeminal ganglion are pseudounipolar, i.e. They give off one process at a time, which, near the cell body, is divided into central and peripheral. The central processes form sensitive root (radix sensorial) and through it they enter the brain stem, reaching the sensory nuclei of the nerve: main core (nucleus principalis nervi trigemini)- in the bridge and spinal nucleus (nucleus spinalis nervi trigemini) - in the lower part of the bridge, in the medulla oblongata and in the cervical segments of the spinal cord. Located in the midbrain mesencephalic nucleus of the trigeminal nerve (nucleus mesencephalicus

Rice. 229. Nerves of the orbit, top view. (The upper wall of the orbit has been removed): 1 - supraorbital nerve; 2 - muscle that lifts the upper eyelid; 3 - superior rectus muscle of the eye; 4 - lacrimal gland; 5 - lacrimal nerve; 6 - lateral rectus oculi muscle; 7 - frontal nerve; 8 - maxillary nerve; 9 - mandibular nerve; 10 - trigeminal node; 11 - tentorium of the cerebellum; 12 - abducens nerve; 13, 17 - trochlear nerve; 14 - oculomotor nerve; 15 - optic nerve; 16 - optic nerve; 18 - nasociliary nerve; 19 - subtrochlear nerve; 20 - superior oblique muscle of the eye; 21 - medial rectus muscle of the eye; 22 - supratrochlear nerve

Rice. 230. Trigeminal nerve (diagram):

1 - mesencephalic nucleus; 2 - main sensitive core; 3 - spinal tract; 4 - facial nerve; 5 - mandibular nerve; 6 - maxillary nerve; 7 - optic nerve; 8 - trigeminal nerve and node; 9 - motor core. The red solid line indicates motor fibers; blue solid line - sensitive fibers; blue dotted line - proprioceptive fibers; red dotted line - parasympathetic fibers; red broken line - sympathetic fibers

nervi trigemini). This nucleus consists of pseudounipolar neurons and is believed to be related to the proprioceptive innervation of the facial and masticatory muscles.

The peripheral processes of the neurons of the trigeminal ganglion are part of the listed main branches of the trigeminal nerve.

Motor nerve fibers originate in motor nucleus of the nerve (nucleus motorius nervi trigemini), lying at the back of the bridge. These fibers leave the brain and form motor root (radix motoria). The place where the motor root exits the brain and the sensory entrance is located at the transition of the pons to the middle cerebellar peduncle. Between the sensory and motor roots of the trigeminal nerve there is often (in 25% of cases)

Rice. 231. Trigeminal nerve, lateral view. (The lateral wall of the orbit and part of the lower jaw have been removed):

1 - trigeminal node; 2 - greater petrosal nerve; 3 - facial nerve; 4 - mandibular nerve; 5 - auriculotemporal nerve; 6 - inferior alveolar nerve; 7 - lingual nerve; 8 - buccal nerve; 9 - pterygopalatine node; 10 - infraorbital nerve; 11 - zygomatic nerve; 12 - lacrimal nerve; 13 - frontal nerve; 14 - optic nerve; 15 - maxillary nerve

anastomotic connections, as a result of which a certain number of nerve fibers pass from one root to another.

The diameter of the sensory root is 2.0-2.8 mm, it contains from 75,000 to 150,000 myelinated nerve fibers with a diameter of mainly up to 5 microns. The thickness of the motor root is less - 0.8-1.4 mm. It contains from 6,000 to 15,000 myelinated nerve fibers with a diameter, usually more than 5 microns.

The sensory root with its trigeminal ganglion and the motor root together make up the trunk of the trigeminal nerve with a diameter of 2.3-3.1 mm, containing from 80,000 to 165,000 myelinated nerve fibers. The motor root bypasses the trigeminal ganglion and becomes part of the mandibular nerve.

Parasympathetic nerve ganglia are connected to the 3 main branches of the trigeminal nerve: the ciliary ganglion - with the ophthalmic nerve, the pterygopalatine ganglion - with the maxillary nerve, the auricular, submandibular and hypoglossal ganglia - with the mandibular nerves.

The general plan for dividing the main branches of the trigeminal nerve is as follows: each nerve (ophthalmic, maxillary and mandibular) gives off a branch to the dura mater; visceral branches - to the mucous membrane of the accessory sinuses, oral and nasal cavities and organs (lacrimal gland, eyeball, salivary glands, teeth); external branches, among which there are medial branches - to the skin of the anterior areas of the face and lateral branches - to the skin of the lateral areas of the face.

Optic nerve

Optic nerve(n. ophthalmicus) is the first, thinnest branch of the trigeminal nerve. It is sensitive and innervates the skin of the forehead and the anterior part of the temporal and parietal regions, the upper eyelid, the back of the nose, as well as partially the mucous membrane of the nasal cavity, the membranes of the eyeball and the lacrimal gland (Fig. 232).

The nerve is 2-3 mm thick, consists of 30-70 relatively small bundles and contains from 20,000 to 54,000 myelinated nerve fibers, mostly of small diameter (up to 5 microns). After originating from the trigeminal ganglion, the nerve passes through the outer wall of the cavernous sinus, where it gives off recurrent shell (tentorial) branch (r. meningeus recurrens (tentorius) to the tentorium of the cerebellum. Near the superior orbital fissure, the optic nerve divides into 3 branches: lacrimal, frontal And nasociliary nerves.

Rice. 232. Nerves of the orbit, top view. (The muscle that lifts the upper eyelid, and the superior rectus and superior oblique muscles of the eye are partially removed): 1 - long ciliary nerves; 2 - short ciliary nerves; 3, 11 - lacrimal nerve; 4 - ciliary node; 5 - oculomotor root of the ciliary ganglion; 6 - additional oculomotor root of the ciliary ganglion; 7 - nasociliary root of the ciliary node; 8 - branches of the oculomotor nerve to the inferior rectus muscle of the eye; 9, 14 - abducens nerve; 10 - lower branch of the oculomotor nerve; 12 - frontal nerve; 13 - optic nerve; 15 - oculomotor nerve; 16 - trochlear nerve; 17 - branch of the cavernous sympathetic plexus; 18 - nasociliary nerve; 19 - superior branch of the oculomotor nerve; 20 - posterior ethmoidal nerve; 21 - optic nerve; 22 - anterior ethmoidal nerve; 23 - subtrochlear nerve; 24 - supraorbital nerve; 25 - supratrochlear nerve

1. Lacrimal nerve(n. lacrimalis) located near the outer wall of the orbit, where it receives connecting branch with the zygomatic nerve (r. communicans cum nervo zygomatico). Provides sensitive innervation to the lacrimal gland, as well as the skin of the upper eyelid and lateral canthus.

2.Frontal nerve(n. frontalis) - the thickest branch of the optic nerve. It passes under the upper wall of the orbit and divides into two branches: supraorbital nerve (n. supraorbital), passing through the supraorbital notch to the skin of the forehead, and supratrochlear nerve (n. supratrochlearis), emerging from the orbit at its inner wall and innervating the skin of the upper eyelid and medial corner of the eye.

3.Nasociliary nerve(n. nasociliaris) lies in the orbit at its medial wall and under the block of the superior oblique muscle exits the orbit in the form of a terminal branch - subtrochlear nerve (n. infratrochlearis), which innervates the lacrimal sac, conjunctiva and medial corner of the eye. Along its length, the nasociliary nerve gives off the following branches:

1)long ciliary nerves (nn. ciliares longi) to the eyeball;

2)posterior ethmoidal nerve (n. ethmoidalis posterior) to the mucous membrane of the sphenoid sinus and the posterior cells of the ethmoidal labyrinth;

3)anterior ethmoidal nerve (n. ethmoidalis anterior) to the mucous membrane of the frontal sinus and nasal cavity (rr. nasales interni laterales et mediales) and to the skin of the tip and wing of the nose.

In addition, a connecting branch departs from the nasociliary nerve to the ciliary ganglion.

Ciliary knot(ganglion ciliare)(Fig. 233), up to 4 mm long, lies on the lateral surface of the optic nerve, approximately on the border between the posterior and middle thirds of the length of the orbit. In the ciliary ganglion, as in other parasympathetic ganglia of the trigeminal nerve, there are parasympathetic multi-process (multipolar) nerve cells on which preganglionic fibers, forming synapses, switch to postganglionic ones. Sensitive fibers pass through the node in transit.

Connecting branches in the form of its roots approach the node:

1)parasympathetic (radix parasympathica (oculomotoria) gangliiciliaris) - from the oculomotor nerve;

2)sensitive (radix sensorial (nasociliaris) ganglii ciliaris) - from the nasociliary nerve.

From the ciliary node extends from 4 to 40 short ciliary nerves (nn. ciliares breves), going inside the eyeball. They contain postganglionic parasympathetic fibers innervating the ciliary muscle, sphincter and, to a lesser extent, the pupillary dilator, as well as sensory fibers to the membranes of the eyeball. (Sympathetic fibers to the dilator muscle are described below.)

Rice. 233. Ciliary node (preparation by A.G. Tsybulkin). Impregnation with silver nitrate, clearing in glycerin. Uv. x 12.

1 - ciliary node; 2 - branch of the oculomotor nerve to the inferior oblique muscle of the eye; 3 - short ciliary nerves; 4 - ophthalmic artery; 5 - nasociliary root of the ciliary node; 6 - accessory oculomotor roots of the ciliary ganglion; 7 - oculomotor root of the ciliary ganglion

Maxillary nerve

Maxillary nerve(n. maxillaries) - second branch of the trigeminal nerve, sensory. It has a thickness of 2.5-4.5 mm and consists of 25-70 small bundles containing from 30,000 to 80,000 myelinated nerve fibers, mostly of small diameter (up to 5 microns).

The maxillary nerve innervates the dura mater of the brain, the skin of the lower eyelid, the lateral corner of the eye, the anterior part of the temporal region, the upper part of the cheek, the wings of the nose, the skin and mucous membrane of the upper lip, the mucous membrane of the posterior and lower parts of the nasal cavity, the mucous membrane of the sphenoid sinus, the palate , teeth of the upper jaw. Upon exiting the skull through the foramen rotundum, the nerve enters the pterygopalatine fossa, passes from back to front and from the inside to the outside (Fig. 234). The length of the segment and its position in the fossa depend on the shape of the skull. With a brachycephalic skull, the length of the segment

The nerve in the fossa is 15-22 mm, it is located deep in the fossa - up to 5 cm from the middle of the zygomatic arch. Sometimes the nerve in the pterygopalatine fossa is covered by a bone crest. In a dolichocephalic skull, the length of the nerve section in question is 10-15 mm; it is located more superficially - up to 4 cm from the middle of the zygomatic arch.

Rice. 234. Maxillary nerve, lateral view. (The wall and contents of the orbit have been removed):

1 - lacrimal gland; 2 - zygomaticotemporal nerve; 3 - zygomaticofacial nerve; 4 - external nasal branches of the anterior ethmoidal nerve; 5 - nasal branch; 6 - infraorbital nerve; 7 - anterior superior alveolar nerves; 8 - mucous membrane of the maxillary sinus; 9 - middle superior alveolar nerve; 10 - dental and gingival branches; 11 - upper dental plexus; 12 - infraorbital nerve in the canal of the same name; 13 - posterior superior alveolar nerves; 14 - nodal branches to the pterygopalatine node; 15 - greater and lesser palatine nerves; 16 - pterygopalatine node; 17 - nerve of the pterygoid canal; 18 - zygomatic nerve; 19 - maxillary nerve; 20 - mandibular nerve; 21 - oval hole; 22 - round hole; 23 - meningeal branch; 24 - trigeminal nerve; 25 - trigeminal node; 26 - optic nerve; 27 - frontal nerve; 28 - nasociliary nerve; 29 - lacrimal nerve; 30 - eyelash node

Within the pterygopalatine fossa, the maxillary nerve gives off meningeal branch (r. meningeus) to the dura mater and divides into 3 branches:

1) nodal branches to the pterygopalatine node;

2) zygomatic nerve;

3) the infraorbital nerve, which is a direct continuation of the maxillary nerve.

1. Nodal branches to the pterygopalatine ganglion(rr. ganglionares ad ganglio pterygopalatinum)(numbering 1-7) depart from the maxillary nerve at a distance of 1.0-2.5 mm from the round foramen and go to the pterygopalatine node, giving sensory fibers to the nerves starting from the node. Some nodal branches bypass the node and join its branches.

Pterygopalatine ganglion(ganglion pterygopalatinum) - formation of the parasympathetic part of the autonomic nervous system. The node is triangular in shape, 3-5 mm long, contains multipolar cells and has 3 roots:

1) sensitive - nodal branches;

2) parasympathetic - greater petrosal nerve (n. petrosus major)(branch of the intermediate nerve), contains fibers to the glands of the nasal cavity, palate, lacrimal gland;

3) sympathetic - deep petrosal nerve (n. petrosus profundus) originates from the internal carotid plexus and contains postganglionic sympathetic nerve fibers from the cervical ganglia. As a rule, the large and deep petrosal nerves unite into the nerve of the pterygoid canal, which passes through the canal of the same name at the base of the pterygoid process of the sphenoid bone.

Branches extend from the node, which include secretory and vascular (parasympathetic and sympathetic) and sensory fibers (Fig. 235):

1)orbital branches (rr. orbitales), 2-3 thin trunks, penetrate through the inferior orbital fissure and then, together with the posterior ethmoidal nerve, go through the small openings of the sphenoid-ethmoidal suture to the mucous membrane of the posterior cells of the ethmoidal labyrinth and the sphenoid sinus;

2)posterior superior nasal branches (rr. nasales posteriores superiors)(8-14 in number) emerge from the pterygopalatine fossa through the sphenopalatine foramen into the nasal cavity and are divided into two groups: lateral and medial (Fig. 236). Lateral branches

Rice. 235. Pterygopalatine node (diagram):

1 - superior salivary nucleus; 2 - facial nerve; 3 - knee of the facial nerve; 4 - greater petrosal nerve; 5 - deep petrosal nerve; 6 - nerve of the pterygoid canal; 7 - maxillary nerve; 8 - pterygopalatine node; 9 - posterior superior nasal branches; 10 - infraorbital nerve; 11 - nasopalatine nerve; 12 - postganglionic autonomic fibers to the mucous membrane of the nasal cavity; 13 - maxillary sinus; 14 - posterior superior alveolar nerves; 15 - greater and lesser palatine nerves; 16 - tympanic cavity; 17 - internal carotid nerve; 18 - internal carotid artery; 19 - upper cervical node of the sympathetic trunk; 20 - autonomous nuclei of the spinal cord; 21 - sympathetic trunk; 22 - spinal cord; 23 - medulla oblongata

(rr. nasales posteriores superiores laterales)(6-10), go to the mucous membrane of the posterior sections of the superior and middle nasal concha and nasal passages, the posterior cells of the ethmoid bone, the upper surface of the choanae and the pharyngeal opening of the auditory tube. Medial branches (rr. nasales posteriores superiores mediales)(2-3), branch in the mucous membrane of the upper part of the nasal septum. One of the medial branches is nasopalatine nerve (n. nasopalatinus) - passes between the periosteum and the mucous membrane

Rice. 236. Nasal branches of the pterygopalatine ganglion, view from the nasal cavity: 1 - olfactory filaments; 2, 9 - nasopalatine nerve in the incisive canal; 3 - posterior superior medial nasal branches of the pterygopalatine ganglion; 4 - posterior superior lateral nasal branches; 5 - pterygopalatine node; 6 - posterior lower nasal branches; 7 - lesser palatine nerve; 8 - greater palatine nerve; 10 - nasal branches of the anterior ethmoidal nerve

the septum together with the posterior artery of the nasal septum forward to the nasal opening of the incisive canal, through which it reaches the mucous membrane of the anterior part of the palate (Fig. 237). Forms a connection with the nasal branch of the superior alveolar nerve.

3) palatal nerves (nn. palatine) spread from the node through the greater palatine canal, forming 3 groups of nerves:

Rice. 237. Sources of innervation of the palate, ventral view (soft tissues removed): 1 - nasopalatine nerve; 2 - greater palatine nerve; 3 - lesser palatine nerve; 4 - soft palate

1)greater palatine nerve (n. palatinus major) - the thickest branch exits through the large palatine foramen onto the palate, where it splits into 3-4 branches that innervate most of the mucous membrane of the palate and its glands in the area from the canines to the soft palate;

2)minor palatine nerves (nn. palatini minores) enter the oral cavity through the small palatine openings and branch in the mucous membrane of the soft palate and the region of the palatine tonsil;

3)lower posterior nasal branches (rr. nasales posteriores inferiors) They enter the greater palatine canal, leave it through small openings and, at the level of the inferior turbinate, enter the nasal cavity, innervating the mucous membrane of the inferior turbinate, middle and lower nasal passages and the maxillary sinus.

2. Zygomatic nerve(n. zygomaticus) branches from the maxillary nerve within the pterygopalatine fossa and penetrates through the inferior orbital fissure into the orbit, where it runs along the outer wall, gives off a connecting branch to the lacrimal nerve, containing secretory parasympathetic fibers to the lacrimal gland, enters the zygomatic orbital foramen and is divided into two branches:

1)zygomaticofacial branch (r. zygomaticofacialis ), which exits through the zygomaticofacial foramen onto the anterior surface of the zygomatic bone; in the skin of the upper part of the cheek it gives off a branch to the area of ​​the outer canthus and a connecting branch to the facial nerve;

2)zygomaticotemporal branch (r. zygomaticotemporalis ), which leaves the orbit through the opening of the same name in the zygomatic bone, pierces the temporalis muscle and its fascia and innervates the skin of the anterior part of the temporal and posterior part of the frontal regions.

3. Infraorbital nerve(n. infraorbitalis ) is a continuation of the maxillary nerve and gets its name after the above branches depart from it. The infraorbital nerve leaves the pterygopalatine fossa through the inferior orbital fissure, passes along the lower wall of the orbit along with the vessels of the same name in the infraorbital groove (in 15% of cases there is a bone canal instead of a groove) and exits through the infraorbital foramen under the muscle that lifts the upper lip, dividing into terminal branches. The length of the infraorbital nerve is different: with brachycephaly, the nerve trunk is 20-27 mm, and with dolichocephaly - 27-32 mm. The position of the nerve in the orbit corresponds to the parasagittal plane drawn through the infraorbital foramen.

The origin of the branches can also be different: scattered, in which numerous thin nerves with many connections depart from the trunk, or mainline with a small number of large nerves. Along its path, the infraorbital nerve gives off the following branches:

1) superior alveolar nerves (nn. alveolares superiors) innervate the teeth and upper jaw (see Fig. 235). There are 3 groups of branches of the superior alveolar nerves:

1) posterior superior alveolar branches (rr. alveolares superiores posteriors) They branch from the infraorbital nerve, as a rule, in the pterygopalatine fossa, numbering 4-8 and located together with the vessels of the same name along the surface of the tubercle of the upper jaw. Some of the most posterior nerves go along the outer surface of the tubercle down to the alveolar process, the rest enter through the posterior superior alveolar foramina into the alveolar canals. Branching together with other superior alveolar branches, they form the nervous superior dental plexus (plexus dentalis superior), which lies in the alveolar process of the upper jaw above the apices of the roots. The plexus is dense, broadly looped, stretched along the entire length of the alveolar process. They depart from the plexus upper gums

superior branches (rr. gingivales superiors) to the periodontium and periodontium in the area of ​​the upper molars and upper dental branches (rr. dentales superiors) - to the tips of the roots of large molars, in the pulp cavity of which they branch. In addition, the posterior superior alveolar branches send thin nerves to the mucous membrane of the maxillary sinus;

2)middle superior alveolar branch (r. alveolaris superior) in the form of one or (less often) two trunks it branches off from the infraorbital nerve, most often in the pterygopalatine fossa and (less often) within the orbit, passes in one of the alveolar canals and branches in the bone canaliculi of the upper jaw as part of the superior dental plexus. It has connecting branches with the posterior and anterior superior alveolar branches. Innervates the periodontium and periodontium in the area of ​​the upper premolars through the upper gingival branches and the upper premolars through the upper dental branches;

3)anterior superior alveolar branches (rr. alveolares superiores anteriores) arise from the infraorbital nerve in the anterior part of the orbit, which leaves through the alveolar canals, penetrating the anterior wall of the maxillary sinus, where they form part of the superior dental plexus. Upper gingival branches innervate the mucous membrane of the alveolar process and the walls of the alveoli in the area of ​​the upper canines and incisors, upper dental branches- upper canines and incisors. The anterior superior alveolar branches send a thin nasal branch to the mucous membrane of the anterior floor of the nasal cavity;

2)lower branches of the eyelids (rr. palpebrales inferiors) they branch from the infraorbital nerve as they exit the infraorbital foramen, penetrate through the levator labii superioris muscle, and, branching, innervate the skin of the lower eyelid;

3)external nasal branches (rr. nasales superiors) innervate the skin in the area of ​​the wing of the nose;

4)internal nasal branches (rr. nasales interni) approach the mucous membrane of the vestibule of the nasal cavity;

5)superior labial branches (rr. labiales superiors)(3-4 in number) go down between the upper jaw and the muscle that lifts the upper lip; innervate the skin and mucous membrane of the upper lip to the corner of the mouth.

All of the listed external branches of the infraorbital nerve form connections with the branches of the facial nerve.

Mandibular nerve

Mandibular nerve(n. mandibularis) - the third branch of the trigeminal nerve is a mixed nerve and is formed by sensory nerve fibers coming from the trigeminal ganglion and motor fibers of the motor root (Fig. 238, 239). The thickness of the nerve trunk ranges from 3.5 to 7.5 mm, and the length of the extracranial part of the trunk is 0.5-2.0 cm. The nerve consists of 30-80 bundles of fibers, including from 50,000 to 120,000 myelinated nerve fibers.

The mandibular nerve provides sensory innervation to the dura mater of the brain, skin of the lower lip, chin, lower part of the cheek, anterior part of the auricle and external auditory canal, part of the surface of the eardrum, mucous membrane of the cheek, floor of the mouth and anterior two-thirds of the tongue, teeth of the lower jaw , as well as motor innervation of all masticatory muscles, the mylohyoid muscle, the anterior belly of the digastric muscle and the muscles that strain the tympanic membrane and the velum palatine.

From the cranial cavity, the mandibular nerve exits through the foramen ovale and enters the infratemporal fossa, where it divides near the exit site into a number of branches. Branching of the mandibular nerve is possible either loose type(more often with dolichocephaly) - the nerve splits into many branches (8-11), or along trunk type(more often with brachycephaly) with branching into a small number of trunks (4-5), each of which is common to several nerves.

Three nodes of the autonomic nervous system are associated with the branches of the mandibular nerve: ear(ganglion oticum);submandibular(ganglion submandibulare);sublingual(ganglion sublinguale). From the nodes postganglionic parasympathetic secretory fibers go to the salivary glands.

The mandibular nerve gives off a number of branches.

1.Meningeal branch(r. meningeus) passes through the foramen spinosum along with the middle meningeal artery into the cranial cavity, where it branches into the dura mater.

2.Masseteric nerve(n. massetericus), predominantly motor, often (especially in the main form of branching of the mandibular nerve) has a common origin with other nerves of the masticatory muscles. It passes outward over the upper edge of the lateral pterygoid muscle, then through the notch of the mandible and is embedded in the masseter muscle. Sends a thin branch before entering the muscle

Rice. 238. Mandibular nerve, left view. (Mandibular ramus removed):

1 - auriculotemporal nerve; 2 - middle meningeal artery; 3 - superficial temporal artery; 4 - facial nerve; 5 - maxillary artery; 6 - inferior alveolar nerve; 7 - mylohyoid nerve; 8 - submandibular node; 9 - internal carotid artery; 10 - mental nerve; 11 - medial pterygoid muscle; 12 - lingual nerve; 13 - drum string; 14 - buccal nerve; 15 - nerve to the lateral pterygoid muscle; 16 - pterygopalatine node; 17 - infraorbital nerve; 18 - maxillary nerve; 19 - zygomaticofacial nerve; 20 - nerve to the medial pterygoid muscle; 21 - mandibular nerve; 22 - chewing nerve; 23 - deep temporal nerves; 24 - zygomaticotemporal nerve

Rice. 239. Mandibular nerve, view from the medial side: 1 - motor root; 2 - sensitive root; 3 - greater petrosal nerve; 4 - lesser petrosal nerve; 5 - nerve to the muscle that strains the eardrum; 6, 12 - drum string; 7 - auriculotemporal nerve; 8 - inferior alveolar nerve; 9 - maxillary-hyoid nerve; 10 - lingual nerve; 11 - medial pterygoid nerve; 13 - ear node; 14 - nerve to the muscle that strains the velum palatine; 15 - mandibular nerve; 16 - maxillary nerve; 17 - optic nerve; 18 - trigeminal node

to the temporomandibular joint, providing its sensitive innervation.

3.Deep temporal nerves(nn. temporales profundi), motor, pass along the outer base of the skull outward, bend around the infratemporal crest and enter the temporal muscle from its inner surface in the anterior (n. temporalis profundus anterior) and rear (n. temporalis profundus posterior) departments

4.Lateral pterygoid nerve(n. pterygoideus lateralis), motor, usually leaves a common trunk with the buccal nerve, approaches the muscle of the same name, in which it branches.

5.Medial pterygoid nerve(n. pterygoideus medialis), mainly motor. It passes through the ear ganglion or is adjacent to its surface and follows forward and down to the inner surface of the muscle of the same name, into which it penetrates near its upper edge. In addition, near the ear node it gives off nerve to the tensor veli palatine muscle (n. musculi tensoris veli palatine), nerve to the tensor tympani muscle (n. musculi tensoris tympani), and a connecting branch to the node.

6.Buccal nerve(n. buccalis), sensitive, penetrates between the two heads of the lateral pterygoid muscle and runs along the inner surface of the temporal muscle, spreading further along with the buccal vessels along the outer surface of the buccal muscle to the corner of the mouth. On its way, it gives off thin branches that pierce the buccal muscle and innervate the mucous membrane of the cheek (to the gum of the 2nd premolar and 1st molar) and branches to the skin of the cheek and corner of the mouth. Forms a connecting branch with the branch of the facial nerve and with the ear ganglion.

7.Auriculotemporal nerve(n. auriculotemporalis ), sensitive, starts from the posterior surface of the mandibular nerve with two roots covering the middle meningeal artery, which then connect into a common trunk. Receives from the ear ganglion a connecting branch containing parasympathetic fibers. Near the neck of the articular process of the lower jaw, the auriculotemporal nerve goes upward and through the parotid salivary gland enters the temporal region, where it branches into terminal branches - superficial temporal (rr. temporales superficiales). Along its path, the auriculotemporal nerve gives off the following branches:

1)articular (rr. articulares), to the temporomandibular joint;

2)parotid (rr. parotidei), to the parotid salivary gland. These branches contain, in addition to sensory ones, parasympathetic secretory fibers from the ear ganglion;

3)nerve of the external auditory canal (n. meatus acustuci externi), to the skin of the external auditory canal and the eardrum;

4)anterior auricular nerves (nn. auriculares anteriores), to the skin of the anterior part of the auricle and the middle part of the temporal region.

8.Lingual nerve(n. lingualis), sensitive. It originates from the mandibular nerve near the foramen ovale and is located between the pterygoid muscles anterior to the inferior alveolar nerve. At the upper edge of the medial pterygoid muscle or slightly lower, it joins the nerve drum string (chorda tympani), which is a continuation of the intermediate nerve.

As part of the chorda tympani, the lingual nerve includes secretory fibers that go to the submandibular and sublingual nerve ganglia, and taste fibers to the papillae of the tongue. Next, the lingual nerve passes between the inner surface of the lower jaw and the medial pterygoid muscle, above the submandibular salivary gland along the outer surface of the hyoglossus muscle to the lateral surface of the tongue. Between the hyoglossus and genioglossus muscles, the nerve splits into terminal lingual branches (rr. linguales).

Along the course of the nerve, connecting branches with the hypoglossal nerve and the chorda tympani are formed. In the oral cavity, the lingual nerve gives off the following branches:

1)branches to the isthmus of the pharynx (rr. isthmi faucium), innervating the mucous membrane of the pharynx and posterior floor of the mouth;

2)hypoglossal nerve (n. sublingualis) departs from the lingual nerve at the posterior edge of the hypoglossal ganglion in the form of a thin connecting branch and spreads forward along the lateral surface of the sublingual salivary gland. Innervates the mucous membrane of the floor of the mouth, gums and sublingual salivary gland;

3)lingual branches (rr. linguales) pass along with the deep arteries and veins of the tongue through the muscles of the tongue forward and end in the mucous membrane of the apex of the tongue and its body to the border line. As part of the lingual branches, taste fibers pass to the papillae of the tongue, passing from the chorda tympani.

9. Inferior alveolar nerve(n. alveolaris inferior), mixed. This is the largest branch of the mandibular nerve. Its trunk lies between the pterygoid muscles behind and lateral to the lingual nerve, between the mandible and the sphenomandibular ligament. The nerve enters, together with the vessels of the same name, into the mandibular canal, where it gives off multiple branches that anastomose with each other and form inferior dental plexus (plexus dentalis inferior)(in 15% of cases), or directly the lower dental and gingival branches. It leaves the canal through the mental foramen, dividing before exiting onto the mental nerve and incisive branch. Gives the following branches:

1) mylohyoid nerve (n. mylohyoides) arises near the entrance of the inferior alveolar nerve into the mandibular foramen, is located in the groove of the same name in the branch of the mandible and goes to the mylohyoid muscle and the anterior belly of the digastric muscle;

2)lower dental and gingival branches (rr. dentales et gingivales inferiors) originate from the inferior alveolar nerve in the mandibular canal; innervate the gums, alveoli of the alveolar part of the jaw and teeth (premolars and molars);

3)mental nerve (n. mentalis) is a continuation of the trunk of the inferior alveolar nerve as it exits through the mental foramen from the canal of the mandible; here the nerve is divided fan-shaped into 4-8 branches, among which there are chin (rr. mentales), to the skin of the chin and lower labials (rr. labials inferiors), to the skin and mucous membrane of the lower lip.

Ear node(ganglion oticum) - rounded flattened body with a diameter of 3-5 mm; located under the foramen ovale on the posteromedial surface of the mandibular nerve (Fig. 240, 241). The lesser petrosal nerve (from the glossopharyngeal) approaches it, bringing preganglionic parasympathetic fibers. A number of connecting branches extend from the node:

1) to the auriculotemporal nerve, which receives postganglionic parasympathetic secretory fibers, which then go as part of the parotid branches to the parotid salivary gland;

2) to the buccal nerve, through which postganglionic parasympathetic secretory fibers reach the small salivary glands of the oral cavity;

3) to the drum string;

4) to the pterygopalatine and trigeminal nodes.

Submandibular node(ganglion submandibulare)(size 3.0-3.5 mm) is located under the trunk of the lingual nerve and is associated with it nodal branches (rr. ganglionares)(Fig. 242, 243). Along these branches the preganglionic parasympathetic fibers of the chorda tympani go to the node and end there. The branches extending from the node innervate the submandibular and sublingual salivary glands.

Sometimes (up to 30% of cases) there is a separate sublingual node(ganglion sublingualis).

VI pair - abducens nerves

Abducens nerve (n. abducens) - motor. Abducens nerve nucleus (nucleus n. abducentis) located in the anterior part of the bottom of the fourth ventricle. The nerve leaves the brain at the posterior edge of the pons, between it and the pyramid of the medulla oblongata, and soon, outside the back of the sella turcica, it enters the cavernous sinus, where it is located along the outer surface of the internal carotid artery (Fig. 244). Further

Rice. 240. Autonomous nodes of the head, view from the medial side: 1 - nerve of the pterygoid canal; 2 - maxillary nerve; 3 - optic nerve; 4 - ciliary node; 5 - pterygopalatine node; 6 - greater and lesser palatine nerves; 7 - submandibular node; 8 - facial artery and nerve plexus; 9 - cervical sympathetic trunk; 10, 18 - internal carotid artery and nerve plexus; 11 - upper cervical node of the sympathetic trunk; 12 - internal carotid nerve; 13 - drum string; 14 - auriculotemporal nerve; 15 - lesser petrosal nerve; 16 - ear node; 17 - mandibular nerve; 19 - sensitive root of the trigeminal nerve; 20 - motor root of the trigeminal nerve; 21 - trigeminal node; 22 - greater petrosal nerve; 23 - deep petrosal nerve

Rice. 241. Ear node of an adult (preparations by A.G. Tsybulkin): a - macromicropreparation, stained with Schiff’s reagent, UV. x12: 1 - mandibular nerve in the foramen ovale (medial surface); 2 - ear node; 3 - sensitive root of the ear node; 4 - connecting branches to the buccal nerve; 5 - additional ear nodes; 6 - connecting branches to the auriculotemporal nerve; 7 - middle meningeal artery; 8 - lesser petrosal nerve; b - histotopogram, hematoxylin-eosin staining, UV. X 10X 7

penetrates through the superior orbital fissure into the orbit and follows forward over the oculomotor nerve. Innervates the external rectus muscle of the eye.

VII pair - facial nerves

Facial nerve(n. facialis) develops in connection with the formation of the second branchial arch (see Fig. 223), therefore it innervates all facial muscles (facial muscles). The nerve is mixed, including motor fibers from its efferent nucleus, as well as sensory and autonomic (gustatory and secretory) fibers belonging to the facial nerve. intermediate nerve(n. intermedins).

Motor nucleus of the facial nerve(nucleus n. facialis) located at the bottom of the IV ventricle, in the lateral region of the reticular formation. The root of the facial nerve leaves the brain together with the root of the intermediate nerve in front of the vestibulocochlear nerve, between

Rice. 242. Submandibular ganglion, lateral view. (Most of the lower jaw has been removed):

1 - mandibular nerve; 2 - deep temporal nerves; 3 - buccal nerve; 4 - lingual nerve; 5 - submandibular node; 6 - submandibular salivary gland; 7 - mylohyoid nerve; 8 - inferior alveolar nerve; 9 - drum string; 10 - auriculotemporal nerve

the posterior edge of the pons and the olive of the medulla oblongata. Next, the facial and intermediate nerves enter the internal auditory canal and enter the facial nerve canal. Here both nerves form a common trunk, making two turns according to the bends of the canal (Fig. 245, 246).

First, the common trunk is positioned horizontally, heading anteriorly and laterally over the tympanic cavity. Then, according to the bend of the facial canal, the barrel turns at a right angle back, forming a knee (geniculum n. facialis) and elbow assembly (ganglion geniculi), belonging to the intermediate nerve. Having passed above the tympanic cavity, the trunk makes a second downward turn, located behind the middle ear cavity. In this area, branches of the intermediate nerve depart from the common trunk, the facial nerve exits the canal

Rice. 243. Submandibular node (preparation by A.G. Tsybulkin): 1 - lingual nerve; 2 - nodal branches; 3 - submandibular node; 4 - glandular branches; 5 - submandibular salivary gland; 6 - branch of the submandibular node to the sublingual gland; 7 - submandibular duct

Rice. 244.Nerves of the oculomotor system (diagram):

1 - superior oblique muscle of the eye; 2 - superior rectus muscle of the eye; 3 - trochlear nerve; 4 - oculomotor nerve; 5 - lateral rectus oculi muscle; 6 - inferior rectus muscle of the eye; 7 - abducens nerve; 8 - inferior oblique muscle of the eye; 9 - medial rectus oculi muscle

Rice. 245. Facial nerve (diagram):

1 - internal carotid plexus; 2 - elbow assembly; 3 - facial nerve; 4 - facial nerve in the internal auditory canal; 5 - intermediate nerve; 6 - motor nucleus of the facial nerve; 7 - superior salivary nucleus; 8 - nucleus of the solitary tract; 9 - occipital branch of the posterior auricular nerve; 10 - branches to the ear muscles; 11 - posterior auricular nerve; 12 - nerve to the stapes muscle; 13 - stylomastoid foramen; 14 - tympanic plexus; 15 - tympanic nerve; 16 - glossopharyngeal nerve; 17 - posterior belly of the digastric muscle; 18 - stylohyoid muscle; 19 - drum string; 20 - lingual nerve (from the mandibular); 21 - submandibular salivary gland; 22 - sublingual salivary gland; 23 - submandibular node; 24 - pterygopalatine node; 25 - ear node; 26 - nerve of the pterygoid canal; 27 - lesser petrosal nerve; 28 - deep petrosal nerve; 29 - greater petrosal nerve

Rice. 246. Intraosseous part of the facial nerve trunk:

1 - greater petrosal nerve; 2 - node of the facial nerve; 3 - facial canal; 4 - tympanic cavity; 5 - drum string; 6 - hammer; 7 - anvil; 8 - semicircular tubules; 9 - spherical bag; 10 - elliptical pouch; 11 - vestibule node; 12 - internal auditory canal; 13 - nuclei of the cochlear nerve; 14 - inferior cerebellar peduncle; 15 - nuclei of the vestibular nerve; 16 - medulla oblongata; 17 - vestibulocochlear nerve; 18 - motor portion of the facial nerve and intermediate nerve; 19 - cochlear nerve; 20 - vestibular nerve; 21 - spiral ganglion

Rice. 247. Parotid plexus of the facial nerve:

a - main branches of the facial nerve, right view: 1 - temporal branches; 2 - zygomatic branches; 3 - parotid duct; 4 - buccal branches; 5 - marginal branch of the lower jaw; 6 - cervical branch; 7 - digastric and stylohyoid branches;

8- main trunk of the facial nerve at the exit from the stylomastoid foramen;

9- posterior auricular nerve; 10 - parotid salivary gland;

b - facial nerve and parotid gland on a horizontal section: 1 - medial pterygoid muscle; 2 - branch of the lower jaw; 3 - chewing muscle; 4 - parotid salivary gland; 5 - mastoid process; 6 - main trunk of the facial nerve;

c - three-dimensional diagram of the relationship between the facial nerve and the parotid salivary gland: 1 - temporal branches; 2 - zygomatic branches; 3 - buccal branches; 4 - marginal branch of the lower jaw; 5 - cervical branch; 6 - lower branch of the facial nerve; 7 - digastric and stylohyoid branches of the facial nerve; 8 - main trunk of the facial nerve; 9 - posterior auricular nerve; 10 - superior branch of the facial nerve

through the stylomastoid foramen and soon enters the parotid salivary gland. The length of the trunk of the extracranial part of the facial nerve ranges from 0.8 to 2.3 cm (usually 1.5 cm), and the thickness - from 0.7 to 1.4 mm; the nerve contains 3500-9500 myelinated nerve fibers, among which thick ones predominate.

In the parotid salivary gland, at a depth of 0.5-1.0 cm from its outer surface, the facial nerve is divided into 2-5 primary branches, which are divided into secondary ones, forming parotid plexus (plexus intraparotideus)(Fig. 247).

There are two forms of the external structure of the parotid plexus: reticulate and trunk. At reticulate form the nerve trunk is short (0.8-1.5 cm), in the thickness of the gland it is divided into many branches that have multiple connections among themselves, as a result of which a narrow-loop plexus is formed. Multiple connections with the branches of the trigeminal nerve are observed. At mainline form the nerve trunk is relatively long (1.5-2.3 cm), divided into two branches (superior and lower), which give rise to several secondary branches; there are few connections between the secondary branches, the plexus is broadly looped (Fig. 248).

Along its path, the facial nerve gives off branches as it passes through the canal, as well as as it exits it. Inside the canal, a number of branches branch off from it:

1.Greater petrosal nerve(n. petrosus major) originates near the genu ganglion, leaves the facial nerve canal through the cleft of the greater petrosal nerve canal and passes along the groove of the same name to the foramen lacerum. Having penetrated the cartilage to the outer base of the skull, the nerve connects with the deep petrosal nerve, forming pterygoid nerve (n. canalis pterygoidei), entering the pterygoid canal and reaching the pterygopalatine node.

The greater petrosal nerve contains parasympathetic fibers to the pterygopalatine ganglion, as well as sensory fibers from cells of the genu ganglion.

2.Stapedial nerve(n. stapedius) - a thin trunk, branches in the canal of the facial nerve at the second turn, penetrates into the tympanic cavity, where it innervates the stapedius muscle.

3.Drum string(chorda tympani) is a continuation of the intermediate nerve, separates from the facial nerve in the lower part of the canal above the stylomastoid foramen and enters through the canaliculus of the chorda tympani into the tympanic cavity, where it lies under the mucous membrane between the long leg of the incus and the handle of the malleus. Through

Rice. 248. Differences in the structure of the facial nerve:

a - network-like structure; b - main structure;

1 - facial nerve; 2 - chewing muscle

Through the petrotympanic fissure, the chorda tympani emerges from the outer base of the skull and merges with the lingual nerve in the infratemporal fossa.

At the point of intersection with the inferior alveolar nerve, the chorda tympani gives off a connecting branch with the auricular ganglion. The chorda tympani consists of preganglionic parasympathetic fibers to the submandibular ganglion and gustatory fibers to the anterior two-thirds of the tongue.

4. Connecting branch with tympanic plexus(r. communicans cum plexus tympanico) - thin branch; starts from the genu ganglion or from the greater petrosal nerve, passes through the roof of the tympanic cavity to the tympanic plexus.

Upon exiting the canal, the following branches depart from the facial nerve.

1.Posterior auricular nerve(n. auricularis posterior) departs from the facial nerve immediately after exiting the stylomastoid foramen, goes back and up along the anterior surface of the mastoid process, dividing into two branches: ear (r. auricularis), innervating the posterior auricular muscle, and occipital (r. occipitalis), innervating the occipital belly of the supracranial muscle.

2.Digastric branch(r. digasricus) arises slightly below the auricular nerve and, going down, innervates the posterior belly of the digastric muscle and the stylohyoid muscle.

3.Connecting branch with glossopharyngeal nerve(r. communicans cum nerve glossopharyngeo) branches near the stylomastoid foramen and spreads anteriorly and down the stylopharyngeal muscle, connecting with the branches of the glossopharyngeal nerve.

Branches of the parotid plexus:

1.Temporal branches(rr. temporales)(2-4 in number) go up and are divided into 3 groups: the anterior ones, innervating the upper part of the orbicularis oculi muscle, and the corrugator muscle; middle, innervating the frontal muscle; posterior, innervating the rudimentary muscles of the auricle.

2.Zygomatic branches(rr. zygomatici)(3-4 in number) spread forward and upward to the lower and lateral parts of the orbicularis oculi muscle and the zygomatic muscle, which innervate.

3.Buccal branches(rr. buccales)(3-5 in number) run horizontally anteriorly along the outer surface of the masticatory muscle and supply branches to the muscles around the nose and mouth.

4.Marginal branch of the mandible(r. marginalis mandibularis) runs along the edge of the lower jaw and innervates the muscles that depress the angle of the mouth and the lower lip, the mental muscle and the laughter muscle.

5. Cervical branch(r. colli) descends to the neck, connects with the transverse nerve of the neck and innervates m. platysma.

Intermediate nerve(n. intermedius) consists of preganglionic parasympathetic and sensory fibers. Sensitive unipolar cells are located in the genu ganglion. The central processes of the cells ascend as part of the nerve root and end in the nucleus of the solitary tract. The peripheral processes of sensory cells go through the chorda tympani and the greater petrosal nerve to the mucous membrane of the tongue and soft palate.

Secretory parasympathetic fibers originate in the superior salivary nucleus in the medulla oblongata. The root of the intermediate nerve leaves the brain between the facial and vestibulocochlear nerves, joins the facial nerve and runs in the facial nerve canal. The fibers of the intermediate nerve leave the facial trunk, passing into the chorda tympani and the greater petrosal nerve, reaching the submandibular, sublingual and pterygopalatine nodes.

Questions for self-control

1.Which cranial nerves are classified as mixed?

2.What cranial nerves develop from the forebrain?

3.What nerves innervate the external muscles of the eye?

4.What branches arise from the optic nerve? Indicate their areas of innervation.

5.What nerves innervate the upper teeth? Where do these nerves come from?

6.What branches of the mandibular nerve do you know?

7.What nerve fibers pass through the chorda tympani?

8.What branches depart from the facial nerve inside their canal? What do they innervate?

9.What branches arise from the facial nerve in the area of ​​the parotid plexus? What do they innervate?

VIII pair - vestibulocochlear nerves

vestibulocochlear nerve(n. vestibulocochlearis)- sensitive, consists of two functionally different parts: vestibule And cochlear(see Fig. 246).

Vestibular nerve (n. vestibularis) conducts impulses from the static apparatus of the vestibule and semicircular canals of the labyrinth of the inner ear. Cochlear nerve (n. cochlearis) ensures the transmission of sound stimuli from the spiral organ of the cochlea. Each part of the nerve has its own sensory nodes containing bipolar nerve cells: the vestibular part - vestibular node(ganglion vestibulare), located at the bottom of the internal auditory canal; cochlear part - cochlear node (spiral node of the cochlea), ganglion cochleare (ganglion spirale cochleare), which is located in the cochlea.

The vestibular node is elongated, there are two parts: upper (pars superior) And lower (pars inferior). The peripheral processes of the cells of the upper part form the following nerves:

1)elliptical saccular nerve (n. utricularis), to the cells of the elliptical sac of the vestibule of the cochlea;

2)anterior ampullary nerve (n. ampularis anterior), to the cells of the sensitive strips of the anterior membranous ampulla of the anterior semicircular canal;

3)lateral ampullary nerve (n. ampulis lateralis), to the lateral membranous ampulla.

From the lower part of the vestibular ganglion, the peripheral processes of cells go in the composition spherical saccular nerve (n. saccularis)

Rice. 249. Vestibulocochlear nerve:

1 - elliptical saccular nerve; 2 - anterior ampullary nerve; 3 - posterior ampullary nerve; 4 - spherical-saccular nerve; 5 - lower branch of the vestibular nerve; 6 - superior branch of the vestibular nerve; 7 - vestibular node; 8 - root of the vestibular nerve; 9 - cochlear nerve

Rice. 250. Glossopharyngeal nerve:

1 - tympanic nerve; 2 - knee of the facial nerve; 3 - lower salivary nucleus; 4 - double core; 5 - nucleus of the solitary tract; 6 - nucleus of the spinal tract; 7, 11 - glossopharyngeal nerve; 8 - jugular foramen; 9 - connecting branch to the auricular branch of the vagus nerve; 10 - upper and lower nodes of the glossopharyngeal nerve; 12 - vagus nerve; 13 - upper cervical node of the sympathetic trunk; 14 - sympathetic trunk; 15 - sinus branch of the glossopharyngeal nerve; 16 - internal carotid artery; 17 - common carotid artery; 18 - external carotid artery; 19 - tonsil, pharyngeal and lingual branches of the glossopharyngeal nerve (pharyngeal plexus); 20 - stylopharyngeal muscle and the nerve to it from the glossopharyngeal nerve; 21 - auditory tube; 22 - tubal branch of the tympanic plexus; 23 - parotid salivary gland; 24 - auriculotemporal nerve; 25 - ear node; 26 - mandibular nerve; 27 - pterygopalatine node; 28 - lesser petrosal nerve; 29 - nerve of the pterygoid canal; 30 - deep petrosal nerve; 31 - greater petrosal nerve; 32 - carotid-tympanic nerves; 33 - stylomastoid foramen; 34 - tympanic cavity and tympanic plexus

to the auditory spot of the saccule and in the composition posterior ampullary nerve (n. ampularis posterior) to the posterior membranous ampulla.

The central processes of the cells of the vestibular ganglion form vestibule (upper) spine, which exits through the internal auditory foramen behind the facial and intermediate nerves and enters the brain near the exit of the facial nerve, reaching the 4 vestibular nuclei in the pons: medial, lateral, superior and inferior.

From the cochlear ganglion, the peripheral processes of its bipolar nerve cells go to the sensitive epithelial cells of the spiral organ of the cochlea, collectively forming the cochlear part of the nerve. The central processes of the cells of the cochlear ganglion form cochlear (lower) spine, going along with the superior root into the brain to the dorsal and ventral cochlear nuclei.

IX pair - glossopharyngeal nerves

Glossopharyngeal nerve(n. glossopharyngeus) - nerve of the third branchial arch, mixed. Innervates the mucous membrane of the posterior third of the tongue, palatine arches, pharynx and tympanic cavity, parotid salivary gland and stylopharyngeal muscle (Fig. 249, 250). The nerve contains 3 types of nerve fibers:

1) sensitive;

2) motor;

3) parasympathetic.

Sensitive fibers - afferent cell processes upper And lower nodes (ganglia superior et inferior). The peripheral processes follow as part of the nerve to the organs where they form receptors, the central ones go to the medulla oblongata, to the sensory nucleus of the solitary tract (nucleus tractus solitarii).

Motor fibers begin from nerve cells common to the vagus nerve double nucleus (nucleus ambiguous) and pass as part of the nerve to the stylopharyngeal muscle.

Parasympathetic fibers originate in the autonomic parasympathetic inferior salivatory nucleus (nucleus salivatorius superior), which is located in the medulla oblongata.

The root of the glossopharyngeal nerve emerges from the medulla oblongata behind the exit site of the vestibulocochlear nerve and, together with the vagus nerve, leaves the skull through the jugular foramen. In this hole the nerve has its first extension - top knot (ganglion superior), and upon exiting the hole - a second expansion - bottom knot (ganglion inferior).

Outside the skull, the glossopharyngeal nerve lies first between the internal carotid artery and the internal jugular vein, and then in a gentle arc bends around the stylopharyngeal muscle behind and outside and approaches from the inside of the hyoglossus muscle to the root of the tongue, dividing into terminal branches.

Branches of the glossopharyngeal nerve.

1.Tympanic nerve(n. tympanicus) branches off from the inferior ganglion and passes through the tympanic canaliculus into the tympanic cavity, where it forms together with the carotid-tympanic nerves tympanic plexus (plexus tympanicus). The tympanic plexus innervates the mucous membrane of the tympanic cavity and the auditory tube. The tympanic nerve leaves the tympanic cavity through its superior wall as lesser petrosal nerve (n. petrosus minor) and goes to the ear node. Preganglionic parasympathetic secretory fibers, which are part of the lesser petrosal nerve, are interrupted in the ear node, and postganglionic secretory fibers enter the auriculotemporal nerve and reach the parotid salivary gland in its composition.

2.Branch of the stylopharyngeal muscle(r. m. stylopharyngei) goes to the muscle of the same name and the mucous membrane of the pharynx.

3.Sinus branch(r. sinus carotid), sensitive, branches in the carotid glomus.

4.Almond branches(rr. tonsillares) are directed to the mucous membrane of the palatine tonsil and arches.

5.Pharyngeal branches(rr. pharyngei)(3-4 in number) approach the pharynx and, together with the pharyngeal branches of the vagus nerve and sympathetic trunk, form on the outer surface of the pharynx pharyngeal plexus (plexus pharyngealis). Branches extend from it to the muscles of the pharynx and to the mucous membrane, which, in turn, form intramural nerve plexuses.

6.Lingual branches(rr. linguales) - terminal branches of the glossopharyngeal nerve: contain sensory taste fibers to the mucous membrane of the posterior third of the tongue.

X pair - vagus nerves

Nervus vagus(n. vagus), mixed, develops in connection with the fourth and fifth gill arches, and is widely distributed due to which it got its name. Innervates the respiratory organs, organs of the digestive system (up to the sigmoid colon), thyroid and parathyroid glands, adrenal glands, kidneys, and participates in the innervation of the heart and blood vessels (Fig. 251).

Rice. 251. Nervus vagus:

1 - dorsal nucleus of the vagus nerve; 2 - nucleus of the solitary tract; 3 - nucleus of the spinal tract of the trigeminal nerve; 4 - double core; 5 - cranial root of the accessory nerve; 6 - vagus nerve; 7 - jugular foramen; 8 - superior node of the vagus nerve; 9 - lower node of the vagus nerve; 10 - pharyngeal branches of the vagus nerve; 11 - connecting branch of the vagus nerve to the sinus branch of the glossopharyngeal nerve; 12 - pharyngeal plexus; 13 - superior laryngeal nerve; 14 - internal branch of the superior laryngeal nerve; 15 - external branch of the superior laryngeal nerve; 16 - superior cardiac branch of the vagus nerve; 17 - lower cardiac branch of the vagus nerve; 18 - left recurrent laryngeal nerve; 19 - trachea; 20 - cricothyroid muscle; 21 - lower pharyngeal constrictor; 22 - middle pharyngeal constrictor; 23 - stylopharyngeal muscle; 24 - superior pharyngeal constrictor; 25 - palatopharyngeal muscle; 26 - muscle that lifts the velum palatine, 27 - auditory tube; 28 - auricular branch of the vagus nerve; 29 - meningeal branch of the vagus nerve; 30 - glossopharyngeal nerve

The vagus nerve contains sensory, motor and autonomic parasympathetic and sympathetic fibers, as well as small intra-stem nerve ganglia.

Sensitive nerve fibers of the vagus nerve originate from afferent pseudounipolar nerve cells, clusters of which form 2 sensory node: superior (ganglion superior), located in the jugular foramen, and lower (ganglion inferior), lying at the exit of the hole. The central processes of the cells go into the medulla oblongata to the sensitive nucleus - nucleus of the solitary tract(nucleus tractus solitarii), and the peripheral ones - as part of the nerve to the vessels, heart and viscera, where they end in receptor apparatus.

Motor fibers for the muscles of the soft palate, pharynx and larynx originate from the upper cells of the motor double core.

Parasympathetic fibers originate from the autonomic dorsal nucleus (nucleus dorsalis nervi vagi) and spread as part of the nerve to the heart muscle, muscle tissue of the membranes of blood vessels and viscera. Impulses traveling along parasympathetic fibers reduce the heart rate, dilate blood vessels, narrow the bronchi, and increase peristalsis of the tubular organs of the gastrointestinal tract.

Autonomous postganglionic sympathetic fibers enter the vagus nerve along its connecting branches with the sympathetic trunk from the cells of the sympathetic ganglia and spread along the branches of the vagus nerve to the heart, blood vessels and viscera.

As noted, the glossopharyngeal and accessory nerves are separated from the vagus nerve during development, so the vagus nerve maintains connections with these nerves, as well as with the hypoglossal nerve and the sympathetic trunk through connecting branches.

The vagus nerve leaves the medulla oblongata behind the olive through numerous roots, merging into a common trunk, which leaves the skull through the jugular foramen. Next, the vagus nerve goes downward as part of the cervical neurovascular bundle, between the internal jugular vein and the internal carotid artery, and below the level of the upper edge of the thyroid cartilage - between the same vein and the common carotid artery. Through the superior thoracic aperture, the vagus nerve penetrates the posterior mediastinum between the subclavian vein and artery on the right and in front of the aortic arch on the left. Here, by branching and connections between the branches, it forms in front of the esophagus (left nerve) and behind it (right nerve) esophageal nerve plexus (plexus oesophagealis), which near the esophageal opening of the diaphragm forms 2 vagus trunk: anterior

(tractus vagalis anterior) And posterior (tractus vagalis posterior), corresponding to the left and right vagus nerves. Both trunks exit the chest cavity through the esophageal opening, give branches to the stomach and end with a number of terminal branches in celiac plexus. From this plexus, fibers of the vagus nerve spread along its branches. Throughout the entire length of the vagus nerve, branches extend from it.

Branches of the cerebral vagus nerve.

1.Meningeal branch(r. meningeus) starts from the superior node and through the jugular foramen reaches the dura mater of the posterior cranial fossa.

2.Auricular branch(r. auricularis) goes from the superior node along the anterolateral surface of the jugular vein bulb to the entrance to the mastoid canal and further along it to the posterior wall of the external auditory canal and part of the skin of the auricle. On its way it forms connecting branches with the glossopharyngeal and facial nerves.

Branches of the cervical vagus nerve.

1.Pharyngeal branches(rr. pharyngeales) originate from the bottom node or immediately below it. They receive thin branches from the upper cervical ganglion of the sympathetic trunk and, between the external and internal carotid arteries, penetrate to the lateral wall of the pharynx, on which, together with the pharyngeal branches of the glossopharyngeal nerve and the sympathetic trunk, they form the pharyngeal plexus.

2.Superior laryngeal nerve(n. laryngeus superior) branches from the lower node and descends down and forward along the lateral wall of the pharynx medially from the internal carotid artery (Fig. 252). At the greater horn, the hyoid bone is divided into two branches: external (r. externus) And internal (r. internus). The external branch connects with branches from the superior cervical ganglion of the sympathetic trunk and runs along the posterior edge of the thyroid cartilage to the cricothyroid muscle and the inferior constrictor of the pharynx, and also intermittently gives branches to the arytenoid and lateral cricoarytenoid muscles. In addition, branches extend from it to the mucous membrane of the pharynx and the thyroid gland. The internal branch is thicker, more sensitive, pierces the thyrohyoid membrane and branches in the mucous membrane of the larynx above the glottis, as well as in the mucous membrane of the epiglottis and the anterior wall of the nasal pharynx. Forms a connecting branch with the inferior laryngeal nerve.

3.Superior cervical cardiac branches(rr. cardiaci cervicales superiors) - variable in thickness and level of branch, usually thin-

cues, originate between the superior and recurrent laryngeal nerves and go down to the cervicothoracic nerve plexus.

4. Inferior cervical cardiac branches(rr. cardiaci cervicales inferiors) depart from the laryngeal recurrent nerve and from the trunk of the vagus nerve; participate in the formation of the cervicothoracic nerve plexus.

Branches of the thoracic vagus nerve.

1. Recurrent laryngeal nerve(n. laryngeus recurrens) arises from the vagus nerve as it enters the chest cavity. The right recurrent laryngeal nerve bends around the subclavian artery from below and behind, and the left one around the aortic arch. Both nerves ascend in the groove between the esophagus and trachea, giving branches to these organs. Final branch - inferior laryngeal nerve (n. laryngeus inferior) fits the larynx

Rice. 252. Laryngeal nerves:

a - right view: 1 - superior laryngeal nerve; 2 - internal branch; 3 - outer branch; 4 - lower pharyngeal constrictor; 5 - cricopharyngeal part of the lower pharyngeal constrictor; 6 - recurrent laryngeal nerve;

b - plate of thyroid cartilage removed: 1 - internal branch of the superior laryngeal nerve; 2 - sensitive branches to the mucous membrane of the larynx; 3 - anterior and posterior branches of the inferior laryngeal nerve; 4 - recurrent laryngeal nerve

and innervates all the muscles of the larynx, with the exception of the cricothyroid, and the mucous membrane of the larynx below the vocal cords.

Branches from the recurrent laryngeal nerve extend to the trachea, esophagus, thyroid and parathyroid glands.

2.Thoracic cardiac branches(rr. cardiaci thoracici) begin from the vagus and left laryngeal recurrent nerves; participate in the formation of the cervicothoracic plexus.

3.Tracheal branches go to the thoracic trachea.

4.Bronchial branches are directed to the bronchi.

5.Esophageal branches approach the thoracic esophagus.

6.Pericardial branches innervate the pericardium.

Within the cavities of the neck and chest, the branches of the vagus, recurrent and sympathetic trunks form the cervicothoracic nerve plexus, which includes the following organ plexuses: thyroid, tracheal, esophageal, pulmonary, cardiac:

Branches of the vagus trunks (ventral part).

1)anterior gastric branches start from the anterior trunk and form the anterior gastric plexus on the anterior surface of the stomach;

2)posterior gastric branches originate from the posterior trunk and form the posterior gastric plexus;

3)celiac branches originate mainly from the posterior trunk and take part in the formation of the celiac plexus;

4)hepatic branches are part of the hepatic plexus;

5)renal branches form renal plexuses.

XI pair - accessory nerve

Accessory nerve(n. accessories) mainly motor, separated during development from the vagus nerve. It begins in two parts - the vagus and the spinal cord - from the corresponding motor nuclei in the medulla oblongata and spinal cord. Afferent fibers enter the trunk through the spinal part from the cells of the sensory nodes (Fig. 253).

The wandering part comes out cranial root (radix cranialis) from the medulla oblongata below the exit of the vagus nerve, the spinal part is formed spinal root (radix spinalis), emerging from the spinal cord between the dorsal and anterior roots.

The spinal part of the nerve rises to the large foramen, enters through it into the cranial cavity, where it connects with the vagus part and forms the common trunk of the nerve.

In the cranial cavity, the accessory nerve divides into two branches: internal And external

1. Internal branch(r. internus) approaches the vagus nerve. Through this branch, motor nerve fibers are included in the vagus nerve, which leave it through the laryngeal nerves. It can be assumed that sensory fibers also pass into the vagus and further into the laryngeal nerve.

Rice. 253. Accessory nerve:

1 - double core; 2 - vagus nerve; 3 - cranial root of the accessory nerve; 4 - spinal root of the accessory nerve; 5 - large hole; 6 - jugular foramen; 7 - superior node of the vagus nerve; 8 - accessory nerve; 9 - lower node of the vagus nerve; 10 - first spinal nerve;

11 - sternocleidomastoid muscle; 12 - second spinal nerve; 13 - branches of the accessory nerve to the trapezius and sternocleidomastoid muscles; 14 - trapezius muscle

2. Outer branch(r. externus) exits from the cranial cavity through the jugular foramen to the neck and goes first behind the posterior belly of the digastric muscle, and then from inside the sternocleidomastoid muscle. Perforating the latter, the external branch goes down and ends in the trapezius muscle. Connections are formed between the accessory and cervical nerves. Innervates the sternocleidomastoid and trapezius muscles.

XII pair - hypoglossal nerve

Hypoglossal nerve(n. hypoglossus) predominantly motor, formed as a result of the fusion of several primary spinal segmental nerves innervating the hypoglossal muscles (see Fig. 223).

The nerve fibers that make up the hypoglossal nerve extend from its cells motor core, located in the medulla oblongata (see Fig. 225). The nerve emerges from it between the pyramid and the olive with several roots. The formed nerve trunk passes through the canal of the hypoglossal nerve to the neck, where it is located first between the external (outside) and internal carotid arteries, and then descends under the posterior belly of the digastric muscle in the form of an open upward arc along the lateral surface of the hypoglossal muscle, constituting the upper side of Pirogov's triangle (lingual triangle) (Fig. 254, see Fig. 193); branches into terminal lingual branches (rr. linguales), innervating muscles of the tongue.

From the middle of the nerve arch goes down along the common carotid artery upper root of the cervical loop (radix superior ansae cervicalis), which connects with her lower root (radix inferior) from the cervical plexus, resulting in the formation neck loop (ansa cervicalis). Several branches extend from the cervical loop to the neck muscles located below the hyoid bone.

The position of the hypoglossal nerve in the neck can vary. In people with long necks, the arc formed by the nerve lies relatively low, while in people with short necks it lies high. This is important to consider when performing nerve operations.

The hypoglossal nerve also contains other types of fibers. Sensitive nerve fibers come from the cells of the lower ganglion of the vagus nerve and, possibly, from the cells of the spinal ganglia along the connecting branches between the hypoglossal, vagus and

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Rice. 254. Hypoglossal nerve:

1 - hypoglossal nerve in the canal of the same name; 2 - nucleus of the hypoglossal nerve; 3 - lower node of the vagus nerve; 4 - anterior branches of the 1st-3rd cervical spinal nerves (form the cervical loop); 5 - upper cervical node of the sympathetic trunk; 6 - upper root of the neck loop; 7 - internal carotid artery; 8 - lower root of the neck loop; 9 - neck loop; 10 - internal jugular vein; 11 - common carotid artery; 12 - lower belly of the omohyoid muscle; 13 - sternothyroid muscle; 14 - sternohyoid muscle; 15 - upper belly of the omohyoid muscle; 16 - thyrohyoid muscle; 17 - hypoglossus muscle; 18 - geniohyoid muscle; 19 - genioglossus muscle; 20 - own muscles of the tongue; 21 - styloglossus muscle

cervical nerves. Sympathetic fibers enter the hypoglossal nerve along its connecting branch with the superior ganglion of the sympathetic trunk.

The areas of innervation, fiber composition and names of the cranial nerve nuclei are presented in Table. 15.

Questions for self-control

1.What nerves arise from the vestibular ganglion?

2.What branches of the glossopharyngeal nerve do you know?

3.What branches arise from the head and cervical parts of the vagus nerve? What do they innervate?

4.What branches of the thoracic and abdominal vagus nerve do you know? What do they innervate?

5.What do the accessory and hypoglossal nerves innervate?

Cervical plexus

Cervical plexus (plexus cervicalis) is formed by the anterior branches of the 4 upper cervical spinal nerves (C I -C IV), which have connections with each other. The plexus lies on the side of the transverse processes between the vertebral (back) and prevertebral (front) muscles (Fig. 255). The nerves emerge from under the posterior edge of the sternocleidomastoid muscle, slightly above its middle, and spread in a fan-like manner upward, forward and downward. The following nerves depart from the plexus:

1.Lesser occipital nerve(n. occipitalis mino)(from C I -C II) spreads upward to the mastoid process and further to the lateral parts of the back of the head, where it innervates the skin.

2.Greater auricular nerve(n. auricularis major)(from C III -C IV) runs along the sternocleidomastoid muscle upward and anteriorly, to the auricle, innervates the skin of the auricle (posterior branch) and the skin above the parotid salivary gland (anterior branch).

3.Transverse cervical nerve(n. transverse colli)(from C III -C IV) goes anteriorly and at the anterior edge of the sternocleidomastoid muscle is divided into upper and lower branches, innervating the skin of the anterior neck.

4.Supraclavicular nerves(nn. supraclaviculars)(from C III -C IV) (from 3 to 5 in number) spread downwards in a fan-like manner under the subcutaneous muscle of the neck; branch in the skin of the posterior lower part of the neck (lateral

Table 15. Areas of innervation, fiber composition and names of cranial nerve nuclei

Continuation of the table. 15

End of table. 15

Rice. 255. Cervical plexus:

1 - hypoglossal nerve; 2 - accessory nerve; 3, 14 - sternocleidomastoid muscle; 4 - great auricular nerve; 5 - lesser occipital nerve; 6 - greater occipital nerve; nerves to the anterior and lateral rectus capitis muscles; 8 - nerves to the long muscles of the head and neck; 9 - trapezius muscle; 10 - connecting branch to the brachial plexus; 11 - phrenic nerve; 12 - supraclavicular nerves; 13 - lower belly of the omohyoid muscle; 15 - neck loop; 16 - sternohyoid muscle; 17 - sternothyroid muscle; 18 - upper belly of the omohyoid muscle; 19 - transverse nerve of the neck; 20 - lower root of the neck loop; 21 - upper root of the neck loop; 22 - thyrohyoid muscle; 23 - geniohyoid muscle

branches), in the region of the clavicle (intermediate branches) and the upper anterior part of the chest to the third rib (medial branches).

5. Phrenic nerve(n. phrenicis)(from C III -C IV and partly from C V), predominantly the motor nerve, goes down the anterior scalene muscle into the chest cavity, where it passes to the diaphragm in front of the root of the lung between the mediastinal pleura and the pericardium. Innervates the diaphragm, gives off sensory branches to the pleura and pericardium (rr. pericardiaci), sometimes to the cervicothoracic nerve

mu plexus. In addition, it sends diaphragmatic-abdominal branches (rr. phrenicoabdominales) to the peritoneum covering the diaphragm. These branches contain nerve ganglia (ganglii phrenici) and connect to the celiac nerve plexus. The right phrenic nerve especially often has such connections, which explains the phrenicussymptom - irradiation of pain to the neck area due to liver disease.

6.Lower root of the cervical loop(radix inferior ansae cervicalis) formed by nerve fibers from the anterior branches of the second and third spinal nerves and goes anteriorly to connect with upper root (radix superior), arising from the hypoglossal nerve (XII pair of cranial nerves). As a result of the connection of both roots, a cervical loop is formed (ansa cervicalis), from which branches extend to the omohyoid, sternohyoid, thyrohyoid and sternothyroid muscles.

7.Muscular branches(rr. musculares) go to the prevertebral muscles of the neck, to the levator scapulae muscle, as well as to the sternocleidomastoid and trapezius muscles.

Cervical sympathetic trunk lies in front of the transverse processes of the cervical vertebrae on the surface of the deep muscles of the neck (Fig. 256). There are 3 cervical nodes in each cervical region: upper, middle (ganglia cervicales superior et media) And cervicothoracic (stellate ) (ganglion cervicothoracicum (stellatum)). The middle cervical node is the smallest. The stellate node often consists of several nodes. The total number of nodes in the cervical region can range from 2 to 6. Nerves extend from the cervical nodes to the head, neck and chest.

1.Gray connecting branches(rr. communicantens grisei)- to the cervical and brachial plexuses.

2.Internal carotid nerve(n. caroticus internus) usually departs from the upper and middle cervical nodes to the internal carotid artery and forms around it internal carotid plexus (plexus caroticus internus), which extends to its branches. Branches off from the plexus deep petrosal nerve (n. petrosus profundus) to the pterygopalatine ganglion.

3.Jugular nerve(n. jugularis) starts from the superior cervical ganglion, within the jugular foramen it divides into two branches: one goes to the superior ganglion of the vagus nerve, the other to the inferior ganglion of the glossopharyngeal nerve.

Rice. 256. Cervical sympathetic trunk:

1 - glossopharyngeal nerve; 2 - pharyngeal plexus; 3 - pharyngeal branches of the vagus nerve; 4 - external carotid artery and nerve plexus; 5 - superior laryngeal nerve; 6 - internal carotid artery and sinus branch of the glossopharyngeal nerve; 7 - carotid glomus; 8 - carotid sinus; 9 - upper cervical cardiac branch of the vagus nerve; 10 - upper cervical cardiac nerve;

11 - middle cervical ganglion of the sympathetic trunk; 12 - middle cervical cardiac nerve; 13 - vertebral node; 14 - recurrent laryngeal nerve; 15 - cervicothoracic (stellate) node; 16 - subclavian loop; 17 - vagus nerve; 18 - lower cervical cardiac nerve; 19 - thoracic cardiac sympathetic nerves and branches of the vagus nerve; 20 - subclavian artery; 21 - gray connecting branches; 22 - upper cervical node of the sympathetic trunk; 23 - vagus nerve

4.Vertebral nerve(n. vertebralis) departs from the cervicothoracic node to the vertebral artery, around which it forms vertebral plexus(plexus vertebralis).

5.Cardiac cervical superior, middle and inferior nerves(nn. cardiaci cervicales superior, medius et inferior) originate from the corresponding cervical nodes and are part of the cervicothoracic nerve plexus.

6.External carotid nerves(nn. carotici externi) extend from the upper and middle cervical nodes to the external carotid artery, where they participate in the formation external carotid plexus (plexus caroticus externus), which extends to the branches of the artery.

7.Laryngopharyngeal branches(rr. laryngopharyngei) go from the superior cervical ganglion to the pharyngeal nerve plexus and as a connecting branch to the superior laryngeal nerve.

8.Subclavian branches(rr. subclavii) move away from subclavian loop (ansa subclavia), which is formed by the division of the internodal branch between the middle cervical and cervicothoracic nodes.

Cranial division of the parasympathetic nervous system

Centers cranial region The parasympathetic part of the autonomic nervous system is represented by nuclei in the brain stem (mesencephalic and bulbar nuclei).

Mesencephalic parasympathetic nucleus - accessory nucleus of the oculomotor nerve (nucleus accessories n. oculomotorii)- located at the bottom of the midbrain aqueduct, medial to the motor nucleus of the oculomotor nerve. Preganglionic parasympathetic fibers go from this nucleus as part of the oculomotor nerve to the ciliary ganglion.

The following parasympathetic nuclei lie in the medulla oblongata and pons:

1)superior salivary nucleus(nucleus salivatorius superior), associated with the facial nerve - in the bridge;

2)inferior salivary nucleus(nucleus salivatorius inferior), associated with the glossopharyngeal nerve - in the medulla oblongata;

3)dorsal nucleus of the vagus nerve(nucleus dorsalis nervi vagi),- in the medulla oblongata.

Preganglionic parasympathetic fibers pass from the cells of the salivary nuclei as part of the facial and glossopharyngeal nerves to the submandibular, sublingual, pterygopalatine and auricular nodes.

Peripheral department parasympathetic nervous system is formed by preganglionic nerve fibers, originating

from the indicated cranial nuclei (they pass as part of the corresponding nerves: III, VII, IX, X pairs), the nodes listed above and their branches containing postganglionic nerve fibers.

1. Preganglionic nerve fibers running as part of the oculomotor nerve follow to the ciliary ganglion and end at synapses on its cells. They depart from the node short ciliary nerves (nn. ciliares breves), in which, along with sensory fibers, there are parasympathetic fibers: they innervate the sphincter of the pupil and the ciliary muscle.

2. Preganglionic fibers from the cells of the superior salivary nucleus spread as part of the intermediate nerve, from it through the greater petrosal nerve they go to the pterygopalatine ganglion, and through the chorda tympani - to the submandibular and hypoglossal nodes, where they end in synapses. From these nodes, postganglionic fibers follow along their branches to the working organs (submandibular and sublingual salivary glands, glands of the palate, nose and tongue).

3. Preganglionic fibers from the cells of the lower salivary nucleus go as part of the glossopharyngeal nerve and further along the lesser petrosal nerve to the ear ganglion, on the cells of which they end in synapses. Postganglionic fibers from the cells of the ear ganglion emerge as part of the auriculotemporal nerve and innervate the parotid gland.

Preganglionic parasympathetic fibers, starting from the cells of the dorsal ganglion of the vagus nerve, pass as part of the vagus nerve, which is the main conductor of parasympathetic fibers. Switching to postganglionic fibers occurs mainly in small ganglia of the intramural nerve plexuses of most internal organs, therefore postganglionic parasympathetic fibers appear to be very short compared to preganglionic fibers.

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Mammals, including humans, have 12 pairs of cranial (cranial) nerves; fish and amphibians have 10, since they have XI and XII pairs of nerves that arise from the spinal cord.

The cranial nerves contain afferent (sensory) and efferent (motor) fibers of the peripheral nervous system. Sensitive nerve fibers begin with terminal receptor endings that perceive changes that occur in the external or internal environment of the body. These receptor endings can enter the sense organs (organs of hearing, balance, vision, taste, smell), or, as, for example, skin receptors, form encapsulated and non-encapsulated endings that are sensitive to tactile, temperature and other stimuli. The sensory fibers carry impulses to the central nervous system. Similar to the spinal nerves, in the cranial nerves the sensory neurons lie outside the central nervous system in the ganglia. The dendrites of these neurons extend to the periphery, and the axons follow into the brain, mainly into the brain stem, and reach the corresponding nuclei.

Motor fibers innervate skeletal muscles. They form neuromuscular synapses on muscle fibers. Depending on which fibers predominate in the nerve, it is called sensory (sensory) or motor (motor). If a nerve contains both types of fibers, it is called a mixed nerve. In addition to these two types of fibers, some cranial nerves contain fibers of the autonomic nervous system, its parasympathetic division.

I pair - olfactory nerves and II pair - optic nerve

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I pair– olfactory nerves (p. olfactorii) and II pair– the optic nerve (n. opticus) occupy a special position: they are classified as the conductive section of the analyzers and are described together with the corresponding sensory organs. They develop as outgrowths of the anterior vesicle of the brain and represent pathways (tracts), rather than typical nerves.

III–XII pairs of cranial nerves

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III–XII cranial nerves differ from spinal nerves due to the fact that the conditions for the development of the head and brain are different than the conditions for the development of the trunk and spinal cord. Due to the reduction of myotomes, there are few neurotomes left in the head area. In this case, the cranial nerves innervating the myotomes are homologous to the incomplete spinal nerve, consisting of the ventral (motor) and dorsal (sensitive) roots. Each somatic cranial nerve includes fibers homologous to one of these two roots. Due to the fact that derivatives of the branchial apparatus take part in the formation of the head, the cranial nerves also include fibers that innervate the formations developing from the muscles of the visceral arches.

III, IV, VI and XII pairs of cranial nerves

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III, IV, VI and XII pairs of cranial nerves - oculomotor, trochlear, abducens and hypoglossal - are motor and correspond to the ventral, or anterior, roots of the spinal nerves. However, in addition to motor fibers, they also contain afferent fibers, along which proprioceptive impulses from the musculoskeletal system rise. III, IV and VI nerves branch in the muscles of the eyeball, originating from the three anterior (preauricular) myotomes, and XII in the muscles of the tongue, developing from the occipital myotomes.

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VIII pair - the vestibulocochlear nerve consists only of sensory fibers and corresponds to the dorsal root of the spinal nerves.

V, VII, IX and X pairs of cranial nerves

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V, VII, IX and X pairs - trigeminal, facial, glossopharyngeal and vagus nerves contain sensory fibers and are homologous to the dorsal roots of the spinal nerves. Like the latter, they consist of neurites of cells of the sensory ganglia of the corresponding nerve. These cranial nerves also contain motor fibers related to the visceral apparatus. The fibers passing as part of the trigeminal nerve innervate the muscles originating from the muscles of the first visceral, jaw arch; as part of the facial - derivatives of the muscles of the II visceral, hyoid arch; as part of the glossopharyngeal - derivatives of the first branchial arch, and the vagus nerve - derivatives of the mesoderm of II and all subsequent branchial arches.

XI pair - accessory nerve

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Pair XI - the accessory nerve consists only of motor fibers of the branchial apparatus and acquires the significance of a cranial nerve only in higher vertebrates. The accessory nerve innervates the trapezius muscle, which develops from the muscles of the last branchial arches, and the sternocleidomastoid muscle, which is separated from the trapezius in mammals.

III, VII, IX, X pairs of cranial nerves

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III, VII, IX, X cranial nerves also contain unmyelinated parasympathetic fibers of the autonomic nervous system. In the III, VII and IX nerves, these fibers innervate the smooth muscles of the eye and glands of the head: salivary, lacrimal and mucous. The X nerve carries parasympathetic fibers to the glands and smooth muscles of the internal organs of the neck, chest and abdominal cavities. This extent of the branching area of ​​the vagus nerve (hence its name) is explained by the fact that the organs innervated by it at the early stages of phylogenesis lay near the head and in the region of the gill apparatus, and then during evolution they gradually moved back, pulling the nerve fibers behind them.

Branches of cranial nerves. All cranial nerves, with the exception of IV, arise from the base of the brain ().

III pair - oculomotor nerve

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III pair - oculomotor nerve (p. oculomotorius) is formed by neurites of cells of the nucleus of the oculomotor nerve, which lies in front of the central gray matter of the aqueduct (see Atl.). In addition, this nerve has an accessory (parasympathetic) nucleus. The nerve is mixed, it emerges on the surface of the brain near the anterior edge of the bridge between the cerebral peduncles and enters the orbit through the superior orbital fissure. Here, the oculomotor nerve innervates almost all the muscles of the eyeball and upper eyelid (see Atl.). After the nerve enters the orbit, parasympathetic fibers leave it and go to the ciliary ganglion. The nerve also contains sympathetic fibers from the internal carotid plexus.

IV pair - trochlear nerve

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IV pair - trochlear nerve (p. trochlearis) consists of fibers of the nucleus of the trochlear nerve, located in front of the aqueduct. The axons of the neurons of this nucleus pass to the opposite side, form a nerve and exit to the surface of the brain from the anterior medullary velum (). The nerve bends around the cerebral peduncle and enters the orbit through the superior orbital fissure, where it innervates the superior oblique muscle of the eye (see Atl.).

V pair - trigeminal nerve

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V pair - trigeminal nerve (n. trigeminus) appears on the surface of the brain between the pons and the middle cerebellar peduncles with two roots: large - sensitive and small - motor (see Atl.).

The sensitive root consists of neurites of sensory neurons of the trigeminal ganglion, which is located on the anterior surface of the pyramid of the temporal bone, near its apex. Having entered the brain, these fibers end in three switching nuclei located: in the tegmentum of the bridge, along the medulla oblongata and cervical spinal cord, on the sides of the aqueduct. The dendrites of the cells of the trigeminal ganglion form three main branches of the trigeminal nerve (hence its name): the orbital, maxillary and mandibular nerves, which innervate the skin of the forehead and face, teeth, mucous membrane of the tongue, oral and nasal cavities (see Atl.; Fig. 3.28 ). Thus, the sensory root of the V pair of nerves corresponds to the dorsal sensory root of the spinal nerve.

Rice. 3.28. Trinity nerve (sensory root):
1 – mesencephalic nucleus; 2 – main sensory nucleus; 3 – IV ventricle; 4 – spinal nucleus; 5 – mandibular nerve; 6 – maxillary nerve; 7 – orbital nerve; 8 – sensory root; 9 – trigeminal ganglion

The motor root contains processes of cells of the motor nucleus, which lies in the tegmentum of the bridge, medial to the switching superior sensory nucleus. Having reached the trigeminal ganglion, the motor root passes it, becomes part of the mandibular nerve, exits the skull through the foramen ovale and supplies with its fibers all the masticatory and other muscles developing from the jaw arch. Thus, the motor fibers of this root are of visceral origin.

VI pair – abducens nerve

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VI pair – abducens nerve (n. abducens), consists of fibers of cells of the nucleus of the same name, lying in a rhomboid fossa. The nerve enters the surface of the brain between the pyramid and the pons, penetrates through the superior orbital fissure into the orbit, where it innervates the external rectus muscle of the eye (see Atl.).

VII pair - facial nerve

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VII pair – facial nerve (p. facialis), consists of fibers of the motor nucleus lying in the tegmentum of the bridge. Together with the facial nerve, the intermediate nerve is considered, the fibers of which join it. Both nerves emerge on the surface of the brain between the pons and the medulla oblongata, lateral to the abducens nerve. Through the internal auditory foramen, the facial nerve, together with the intermediate nerve, penetrates the canal of the facial nerve, which penetrates the pyramid of the temporal bone. In the canal of the facial nerve lies geniculate ganglion – sensory ganglion of the intermediate nerve. It gets its name from the bend (elbow) that forms the nerve in the bend of the canal. Having passed through the canal, the facial nerve separates from the intermediate nerve, exits through the stylomastoid foramen into the thickness of the parotid salivary gland, where it splits into terminal branches that form the “large crow's foot” (see Atl.). These branches innervate all facial muscles, the subcutaneous muscle of the neck and other muscles derived from the mesoderm of the hyoid arch. The nerve thus belongs to the visceral apparatus.

Intermediate nerve consists of a small number of fibers that extend from geniculate ganglion, lying in the initial part of the facial canal. Having entered the brain, these fibers end in the tegmentum of the bridge (on the cells of the nucleus of the solitary bundle). The dendrites of the cells of the geniculate ganglion are part of the chorda tympani - a branch of the intermediate nerve, and then join the lingual nerve (branch of the V pair) and innervate the taste (fungiform and foliate) papillae of the tongue. These fibers, carrying impulses from the taste organs, are homologous to the dorsal roots of the spinal cord. The remaining fibers of the intermediate nerve are parasympathetic, they originate from the superior salivary nucleus. These fibers reach the pterygopalatine ganglion.

VIII pair – vestibulocochlear nerve

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VIII pair – vestibular-cochlear nerve (p. vestibulocochlearis), consists of sensory fibers of the cochlear nerve and the vestibule nerve.

Cochlear nerve conducts impulses from the organ of hearing and is represented by cell neurites spiral knot, lying inside the bony cochlea.

Nerve of the vestibule carries impulses from the vestibular apparatus; they signal the position of the head and body in space. The nerve is represented by neurites of cells vestibule node, located at the bottom of the internal auditory canal.

The neurites of the vestibule and cochlear nerves unite in the internal auditory canal to form the common vestibular-cochlear nerve, which enters the brain next to the intermediate and facial nerves lateral to the olive medulla oblongata.

The cochlear nerve fibers end in the dorsal and ventral auditory nuclei of the pontine tegmentum, and the vestibular nerve fibers end in the vestibular nuclei of the rhomboid fossa (see Atl.).

IX pair - glossopharyngeal nerve

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IX pair – glossopharyngeus nerve (p. glossopharyngeus), appears on the surface of the medulla oblongata, outside the olive, with several roots (from 4 to 6); exits from the cranial cavity through a common trunk through the jugular foramen. The nerve consists mainly of sensory fibers that innervate the grooved papillae and the mucous membrane of the posterior third of the tongue, the mucous membrane of the pharynx and middle ear (see Atl.). These fibers are the dendrites of the cells of the sensory ganglia of the glossopharyngeal nerve, located in the area of ​​the jugular foramen. The neurites of the cells of these nodes end in the switching nucleus (single fascicle), under the bottom of the fourth ventricle. Some fibers pass to the posterior nucleus of the vagus nerve. The described part of the glossopharyngeal nerve is homologous to the dorsal roots of the spinal nerves.

The nerve is mixed. It also contains motor fibers of gill origin. They start from the motor (double) nucleus of the tegmentum of the medulla oblongata and innervate the muscles of the pharynx. These fibers represent nerve I of the branchial arch.

The parasympathetic fibers that make up the nerve originate from the inferior salivary nucleus.

X pair – vagus nerve

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X pair – vagus nerve (p. vagus), the longest of the cranial ones, leaves the medulla oblongata behind the glossopharyngeal with several roots and leaves the skull through the jugular foramen along with the IX and XI pairs. Near the opening are located the ganglia of the vagus nerve, giving rise to its sensitive fibers(see Atl.). Having descended along the neck as part of its neurovascular bundle, the nerve is located in the chest cavity along the esophagus (see Atl.), and the left one gradually shifts to the anterior surface, and the right one to its posterior surface, which is associated with the rotation of the stomach in embryogenesis. Having passed along with the esophagus through the diaphragm into the abdominal cavity, the left nerve branches on the anterior surface of the stomach, and the right one is part of celiac plexus.

Sensitive fibers of the vagus nerve innervate the mucous membrane of the pharynx, larynx, root of the tongue, as well as the dura mater of the brain and are the dendrites of the cells of its sensory ganglia. The dendrites of the cells end in the nucleus of a single bundle. This nucleus, like the double nucleus, is common to nerves IX and X pairs.

Motor fibers The vagus nerve originates from the cells of the double tegmental nucleus of the medulla oblongata. The fibers belong to the nerve II of the branchial arch; they innervate the derivatives of its mesoderm: the muscles of the larynx, palatine arches, soft palate and pharynx.

The bulk of the fibers of the vagus nerve are parasympathetic fibers, originating from the cells of the posterior nucleus of the vagus nerve and innervating the viscera.

XI pair - accessory nerve

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XI pair – accessory nerve (n. accessorius), consists of fibers of the cells of the double nucleus (common with the IX and X nerves), located in the medulla oblongata outside the central canal, and the fibers of its spinal nucleus, which is located in the anterior horns of the spinal cord over 5–6 cervical segments. The roots of the spinal nucleus, having formed a common trunk, enter through the foramen magnum into the skull, where they join the roots of the cranial nucleus. The latter, 3–6 in number, emerge behind the olive, located directly behind the roots of the X pair.

The accessory nerve leaves the skull along with the glossopharyngeal and vagus nerves through the jugular foramen. Here are the fibers of it internal branch become part of the vagus nerve (see Atl.).

enters the cervical plexus and innervates the trapezius and sternocleidomastoid muscles - derivatives of the branchial apparatus (see Atl.).

Cranial nerves make our lives easier every day, as they ensure the functioning of our body and the connection of the brain with the senses.

What it is?

How many are there in total and what functions does each of them perform? How are they usually classified?

General information

The cranial nerve is a collection of nerves that begin or end in the brainstem. There are 12 nerve pairs in total. Their numbering is based on the order of exit:

• I – responsible for the sense of smell
• II – responsible for vision
• III – allows the eyes to move
• IV – directs the eyeball down and out;
• V – is responsible for the measure of sensitivity of facial tissues.
• VI – abducts the eyeball
• VII – connects facial muscles and lacrimal glands with the CNS (central nervous system);
• VIII – transmits auditory impulses, as well as impulses emitted by the vestibular part of the inner ear;
• IX - moves the stylopharyngeal muscle, which lifts the pharynx, connects the parotid gland with the central nervous system, makes the tonsils, pharynx, soft palate, etc. sensitive;
• X - innervates the chest and abdominal cavities, cervical organs and head organs;
• XI - provides nerve cells with muscle tissue that turns the head and raises the shoulder;
• XII - responsible for the movements of the lingual muscles.

Leaving the brain area, the cranial nerves go to the skull, which has characteristic openings for them. They exit through them, and then branching occurs.

Each of the nerves of the skull is different in composition and functionality.

How does it differ from, for example, a spinal cord nerve: the spinal nerves are predominantly mixed, and diverge only in the peripheral region, where they are divided into 2 types. FMNs represent either one or the other type and in most cases are not mixed. Pairs I, II, VIII are sensitive, and III, IV, VI, XI, XII are motor. The rest are mixed.

Classification

There are 2 fundamental classifications of nerve pairs: by location and functionality:
At exit point:

• extending above the brain stem: I, II;
• the exit site is the midbrain: III, IV;
• the exit point is Varoliev Bridge: VIII,VII,VI,V;
• the exit site is the medulla oblongata, or rather its bulb: IX, X, XII and XI.

By functional purpose:

• perception functions: I, II, VI, VIII;
• motor activity of the eyes and eyelids: III, IV, VI;
• motor activity of the cervical and lingual muscles: XI and XII
• parasympathetic functions: III, VII, IX, X

Let's take a closer look at the functionality:

ChMN functionality

Sensitive group

I – olfactory nerve.
Consists of receptors, which are thin processes that thicken towards the end. There are special hairs on the ends of the processes that capture odors.
II – nerve of vision.
It runs through the entire eye, ending in the visual canal. At the exit from it, the nerves cross, after which they continue their movement to the central part of the brain. The visual nerve delivers signals received from the outside world to the necessary sections of the brain.
VIII – vestibulocochlear nerve.
Belongs to the sensory type. Consists of 2 components, different in functionality. The first conducts impulses emanating from the vestibule of the inner ear, and the second transmits hearing impulses that emanate from the cochlea. In addition, the vestibular component is involved in regulating the position of the body, arms, legs and head and, in general, coordinates movements.

Motor group

III – oculomotor nerve.

These are processes of nuclei. Runs from the midbrain to the orbit. Its function is to engage the muscles of the eyelashes, which carry out accommodation, and the muscle that constricts the pupil.

IV - trochlear nerve.

It is of the motor type, located in the orbit, entering there through a gap from above (on the side of the previous nerve). It ends at the eyeball, or more precisely its superior muscle, which it supplies with nerve cells.

VI – abducens nerve.

Like the block one, it is motor. It is formed by processes. It is located in the eye, where it penetrates from above, and provides nerve cells to the external eye muscle.

XI – accessory nerve.

Representative of the motor type. Dual-core. The nuclei are located in the spinal cord and medulla oblongata.

XII – hypoglossal nerve.

Type - motor. Nucleus in the medulla oblongata. Provides nerve cells to the muscles and muscles of the tongue and some parts of the neck.

Mixed group

V – trigeminal.

Leader in thickness. It got its name because it has several branches: ophthalmic, mandibular and maxillary.

VII – facial nerve.

It has a front and an intermediate component. The facial nerve forms 3 branches and provides normal movement of the facial muscles.

IX – glossopharyngeal nerve.

Belongs to the mixed type. Consists of three types of fibers.

X – vagus nerve.

Another representative of the mixed type. Its length exceeds that of the others. Consists of three types of fibers. One branch is the depressor nerve, ending in the aortic arch, regulating blood pressure. The remaining branches, which have a higher susceptibility, provide nerve cells to the membrane of the brain and the skin of the ears.

It can be divided (conditionally) into 4 parts: the head section, the neck section, the chest section and the abdominal section. The branches extending from the head go to the brain and are called meningeal. And those that suit the ears are ear-friendly. The pharyngeal branches come from the neck, and the cardiac branches and thoracic branches depart from the chest, respectively. The branches directed to the plexus of the esophagus are called esophageal.

What can failure lead to?

The symptoms of the lesions depend on which nerve was damaged:

Olfactory nerve

Symptoms appear more or less pronounced, depending on the severity of the nerve damage. Basically, the defeat manifests itself in the fact that a person either senses odors more acutely, or does not distinguish between them, or does not feel them at all. A special place can be given to cases when symptoms appear only on one side, since their bilateral manifestation usually means that a person has chronic rhinitis

Optic nerve

If it is affected, vision deteriorates to the point of blindness on the side where it occurred. If part of the retinal neurons is affected or during the formation of a scotoma, there is a risk of local vision loss in a certain area of ​​the eye. If blindness develops bilaterally, it means that the optic fibers have been affected at the crosshairs. If damage occurs to the middle visual fibers, which completely intersect, then half of the visual field may fall out.

However, there are also cases when the visual field is lost in only one eye. This usually occurs due to damage to the optic tract itself.

Oculomotor nerve

When the nerve trunk is damaged, the eyes stop moving. If only part of the nucleus is affected, then the external eye muscle becomes immobilized or very weak. If, however, complete paralysis occurs, then the patient has no way to open his eyes. If the muscle responsible for raising the eyelid is very weak, but still functions, the patient will be able to open the eye, but only partially. The muscle that raises the eyelid is usually the last to be damaged. But if the damage reaches it, it can cause divergent strabismus or external ophthalmoplegia.

Trochlear nerve

Defeats for this couple are quite rare. It is expressed in the fact that the eyeball loses the ability to move freely outward and downward. This happens due to a violation of innervation. The eyeball seems to freeze in a position turned inward and upward. A characteristic feature of such damage will be double vision or diplopia, when the patient tries to glance down, to the right, or to the left.

Trigeminal nerve

The main symptom is segmental disturbance of perception. Sometimes sensitivity to pain or temperature may be completely lost. At the same time, the sensation from changes in pressure or other deeper changes are perceived adequately.

If the facial nerve is inflamed, then the half of the face that was affected hurts. The pain is localized in the ear area. Sometimes the pain can spread to the lips, forehead or lower jaw. If the optic nerve is affected, the corneal and brow reflexes disappear.

In cases of damage to the mandibular nerve, the tongue almost completely (2/3 of its area) loses the ability to distinguish tastes, and if its motor fiber is damaged, it can paralyze the masticatory muscles.

Abducens nerve

The main symptom is convergent strabismus. Most often, patients complain that they have double vision, and objects that are located horizontally appear double.

However, defeat of this particular pair separately from others rarely occurs. Most often, 3 pairs of nerves (III, IV and VI) are affected at once, due to the proximity of their fibers. But if the lesion has already occurred at the exit from the skull, then most likely the lesion will reach the abducens nerve, due to its greater length compared to the others.

Facial nerve

If the motor fibers are damaged, it can paralyze the face. Facial paralysis occurs on the affected half, which manifests itself in facial asymmetry. This is complemented by Bell syndrome - when trying to close the affected half, the eyeball turns upward.

Since one half of the face is paralyzed, the eye does not blink and begins to water - this is called paralytic lacrimation. Facial muscles can also be immobilized if the motor nucleus of the nerve is damaged. If the lesion also affects the radicular fibers, then this is fraught with the manifestation of Millard-Hubler syndrome, which manifests itself in blocking the movement of the arms and legs on the unaffected half.

vestibulocochlear nerve

When nerve fibers are damaged, hearing is not lost at all.
However, various hearing problems, irritation and hearing loss, even deafness, can easily occur if the nerve itself is damaged. Hearing acuity decreases if the lesion is of a receptor nature or if the anterior or posterior nucleus of the cochlear component of the nerve is damaged.

Glossopharyngeal nerve

If he is affected, the back of the tongue ceases to distinguish tastes, the top of the pharynx loses its receptivity, and the person confuses tastes. Loss of taste is most likely when the projection cortical areas are damaged. If the nerve itself is irritated, the patient feels a burning pain of ragged intensity in the tonsils and tongue, at intervals of 1-2 minutes. Pain can also occur in the ear and throat. When palpated, most often between attacks, the pain sensation is strongest behind the lower jaw.

Nervus vagus

If it is affected, the esophageal and swallowing muscles are paralyzed. Swallowing becomes impossible, and liquid food enters the nasal cavity. The patient speaks through his nose and wheezes, since the vocal cords are also paralyzed. If the nerve is affected on both sides, a suffocating effect may occur. Bari- and tachycardia begins, breathing becomes impaired and the heart may malfunction.

Accessory nerve

If the lesion is one-sided, it becomes difficult for the patient to raise his shoulders, and his head does not turn in the direction opposite to the affected area. But it leans towards the affected area willingly. If the lesion is bilateral, then the head cannot turn in either direction and falls back.

Hypoglossal nerve

If it is affected, the tongue will be completely or partially paralyzed. Paralysis of the periphery of the tongue is most likely if the nucleus or nerve fibers are affected. If the lesion is one-sided, the functionality of the tongue is slightly reduced, but if it is bilateral, the tongue paralyzes, and it can also paralyze the limbs.