Cranial nerves in 12 pairs arise from the brain. These include: I pair - olfactory nerve, II pair - optic nerve, III pair - oculomotor nerve, IV pair - trochlear nerve, V pair - trigeminal nerve, VI pair - abducens nerve, VII pair - facial nerve, VIII pair - vestibular nerve -cochlear nerve, X pair - glossopharyngeal nerve, X pair - vagus nerve, XI pair - accessory nerve, XII pair - hypoglossal nerve (Fig. 24). In their structure and function, the cranial nerves differ significantly from the spinal nerves with the exception of pairs I and II. Sensitive fibers of nerves are peripheral processes of nerve cells embedded in special ganglia, which are equivalent to the intervertebral nodes of the spinal nerves. The central processes of these cells enter the sensory nuclei of the brain stem, which are essentially analogues of the dorsal horns spinal cord. The motor fibers of the cranial nerves arise from the motor nuclei of the brainstem, which are similar to the anterior (motor) horns of the spinal cord. However, unlike the spinal nerves, which are always displaced, three cranial nerves are purely sensory (olfactory, optic and vestibulocochlear), six are purely motor (oculomotor, trochlear, abducens, facial, accessory and hypoglossal) and three are mixed ( trigeminal, glossopharyngeal and vagus) (Fig. 25).

Rice. 24.

The openings through which the cranial nerves enter and exit on the right and left are depicted (nerves passing through the openings are indicated in brackets):

1 - optic chiasm (chiasm); 2 - orbital nerve; 3 - maxillary nerve; 4 - mandibular nerve; 5 - trigeminal node; 6 - foramen magnum; 7 - canal of the hypoglossal nerve (XII); 8 - jugular foramen (IX, X, XI); 9 - internal auditory opening (VII, VIII); 10 - foramen ovale (lower branch of V - mandibular nerve); 11 - round foramen (middle branch of V - maxillary nerve); 12 - superior orbital fissure (III, IV, VI, superior branch V - orbital nerve); 13 - optic nerve canal (II), 14 - cribriform plate (I)

Olfactory nerve

I pair - olfactory nerve. The nerve cells of the first neuron that form it lie in upper section nasal mucosa. These cells directly perceive irritation (molecules of an odorous substance or waves from vibrations of atoms in the air) and transmit it further through the central processes. The second neuron is located in the olfactory bulb, which lies at the base of the brain. Along the olfactory tract, starting from the olfactory bulb, the processes of the second neurons reach the primary olfactory centers (olfactory triangle, visual thalamus and other formations where the third neuron lies).

Fibers from the third neuron go to the cortical olfactory centers, which are located mainly in the hippocampal gyrus (see Fig. 6, 8). The hippocampal gyrus is part of the so-called limbic system, which takes part in the regulation of autonomic functions and emotional reactions associated with instincts.

Optic nerve

II. pair - optic nerve. Like the olfactory nerve, the optic nerve is essentially a reduced part of the brain brought to the periphery. The optic nerve is part of the visual analyzer system. In the retina (inner) shell of the eye there is a receptor apparatus - rods and cones that perceive light stimulation. The first neuron is the ganglion cell. Their peripheral processes are connected to rods (responsible for black-and-white perception) and cones (responsible for color perception). Their central processes make up the optic nerve. The optic nerves exit the eye sockets through the orbital foramen into the cranial cavity, located at the base of the brain. Anterior to the sella turcica, the optic nerves make a partial decussation (optic chiasm). Only the fibers coming from the inner halves of the retinas intersect. The fibers from the outer halves of the retinas remain uncrossed.

Due to the optical properties of the eye left half the retina perceives light from right side visual field and, conversely, the right half of the retina perceives light from the left side of the visual field. This means that the left half of the retina corresponds to the right visual field, and the right half corresponds to the left visual field (Fig. 26). Thus, after the optic chiasm, each optic tract carries fibers from the outer half of the retina of its own eye and the inner half of the retina of the opposite eye. The visual tracts are directed to the primary visual centers - the external geniculate body, the cushion of the visual thalamus and the anterior tubercles of the quadrigeminal. In the external geniculate bodies of the optic thalamus there is a second neuron, from which the path to occipital part cerebral cortex.

A - microscopic structure of the retina: 1 - retinal pigment epithelium; 2 - cones and rods; 3 - bipolar cells; 4 - ganglion cells; 5 - optic nerve; b - optic nerve path: 1 - visual fields; 2 - retina; 3 - optic nerve; 4 - chiasm; 5 - visual tract; 6 - lateral geniculate bodies; 7 - occipital lobe cortex; c - changes in visual fields when the visual pathway is damaged at various levels: 1 - right-sided ambiopia (amaurosis); 2 - heteronymous (binasal) hemianopsia; 3 - heteronymous (bitemporal) hemianopsia; 4 - left-sided homonymous hemianopsia; 5 - left-sided homonymous hemianopsia with preservation of central vision; 6 -

Fibers from the upper quadrant of the retina pass in the upper part of the optic tract and are projected into the region of the occipital lobe located above the calcarine sulcus. Fibers from the lower quadrant of the retina pass in the lower part of the optic tracts and project to the areas of the occipital cortex located below the calcarine sulcus.

The upper quadrants of the retinas correspond to the lower quadrants of the visual fields, and the lower quadrants of the retinas correspond to the upper quadrants of the visual fields. Thus, the outer half of the retina of one’s eye and the inner half of the retina of the opposite eye are projected in the occipital lobe of the cerebral cortex; they correspond to opposite fields of vision. Similarly, the lower quadrants of the visual fields are projected above the calcarine sulcus, and the upper quadrants of the visual fields are projected below the calcarine sulcus.

In the anterior tubercles of the quadrigeminal region there is a reflex center for the reaction of the pupil to light. When the eye is illuminated, the pupil contracts, and when it is darkened, it expands (direct reaction of the pupil to light). However, when one eye is illuminated, the pupil in the other eye also narrows (friendly reaction of the pupil to light).

The reflex arc of the pupillary reflex closes at the level of the quadrigeminal. Some of the fibers of the optic tract end in the anterior colliculus. Here the impulse is transmitted to the nuclei of the oculomotor nerves of one’s own and the other side, due to which the pupil constricts on one’s own and the opposite side.

Oculomotor nerve

III pair - oculomotor nerve. It innervates the muscles that move the eyeball and the muscle that constricts the pupil and changes the curvature of the lens. This change in the curvature of the lens adjusts the eye for better vision at near and far distances (accommodation).

The following eye muscles are distinguished (Fig. 27): superior rectus (moves the eyeball upward), inferior rectus (moves the eyeball downward), external rectus (moves the eyeball outward), internal rectus (moves the eyeball inward), superior oblique, or trochlear muscle (moves the eyeball downward outward due to the oblique arrangement), inferior oblique muscle (moves the eyeball upward outward also due to the oblique arrangement).

There is, in addition, a seventh muscle - the levator muscle upper eyelid.

Upper quadrant homonymous hemianopsia; 7 - lower quadrant homonymous hemianopsia

Oculomotor nerve (III) - innervates the superior rectus, inferior rectus, internal rectus, inferior oblique muscles; abducens nerve (VI) - external rectus muscle; trochlear nerve (IV) - superior oblique muscle. Top left shows the direction of movement of the eyeball during contraction of these muscles.

The oculomotor nerve innervates the following muscles: superior, inferior, internal rectus, inferior oblique, levator superior eyelid.

The nuclei of the oculomotor nerve are located in the cerebral peduncles, at the bottom of the cerebral aqueduct at the level of the superior colliculi. There are three of these nuclei: the external paired nucleus provides innervation to the oculomotor muscles; the internal paired nucleus innervates the muscle that constricts the pupil; The internal unpaired nucleus innervates the ciliary muscle, which changes the curvature of the lens.

Fibers from the nuclei of the brain extend to the base of the brain at the inner side of the cerebral peduncles, at their border with the pons. The third nerve enters the orbital cavity through the orbital fissure.

Trochlear nerve

IV pair - trochlear nerve. Innervates one muscle - the superior oblique muscle, which rotates the eyeball down and out. The nerve nucleus is located at the bottom of the Sylvian aqueduct at the level of the posterior tuberosities of the quadrigeminal. The nerve fibers leave the brain behind the posterior tubercles of the quadrigeminal and bend around the outer side of the cerebral peduncle, entering the orbit through the orbital fissure.

Trigeminal nerve

V pair - trigeminal nerve (mixed). It provides motor and sensory innervation, provides sensitivity from the skin of the face, the anterior part of the scalp, the mucous membrane of the nasal and oral cavities, the tongue, the eyeball, and the meninges. The motor fibers of the nerve innervate the masticatory muscles (masseter, temporal, pterygoid). The sensory fibers of the trigeminal nerve, like the spinal nerves, begin in the sensory ganglion - a powerful node lying on the anterior surface of the pyramid temporal bone. The peripheral processes of the nerve cells of this node end in receptors in the face, scalp, etc., and their central processes go to the sensory nuclei of the trigeminal nerve. There are two of these cores. One nucleus, the superior sensory one, receives fibers of tactile and joint-muscular sensitivity. Another nucleus, the nucleus of the spinal tract of the trigeminal nerve, receives fibers of pain and temperature sensitivity. The superior sensory nucleus of the trigeminal nerve lies in the pons. The elongated nucleus of the spinal tract of the trigeminal nerve descends from above (its head section is located in the pons) down to the upper cervical segments of the spinal cord. This nucleus, like the spinal cord, has a segmental structure. It distinguishes five segments, each of which provides sensitive innervation to a certain part of the face (Fig. 28).

In the sensory nuclei of the trigeminal nerve the second neurons of the sensory pathways from the face are located. The fibers coming from them (forming the so-called trigeminal loop) move to the opposite side and join the medial lemniscus(common sensory pathway from the spinal cord to the thalamus). The third neuron lies in the optic thalamus.

The motor nucleus is located in the pons.

At the base of the brain, the trigeminal nerve emerges from the thickness of the pons in the region of the cerebellopontine angle. Three branches arise from the trigeminal ganglion (see Fig. 28). The superior branch of the trigeminal nerve - the ophthalmic nerve - leaves the cranial cavity through the superior orbital fissure and provides sensitive innervation to the skin of the forehead, anterior scalp, upper eyelid, inner corner of the eye, dorsum of the nose, eyeball, mucous membrane of the upper part of the nasal cavity, meninges .

The second branch of the trigeminal nerve, the maxillary nerve, exits the cranial cavity through the round opening (in the cheek area under the zygomatic bone) and innervates the skin of the lower eyelid, outer corner of the eye, upper cheeks, upper lip, upper jaw and its teeth, mucous membrane of the lower part of the nasal cavities.

A - orbital branch of the trigeminal nerve; 6 - maxillary branch of the trigeminal nerve; c - mandibular branch of the trigeminal nerve; A - zones of innervation of the branches of the trigeminal nerve; B - segmental nature of the sensitive innervation of the face (segments 1-5 of the sensory nucleus of the trigeminal nerve and the corresponding innervation zones on the face).

The third branch of the trigeminal nerve - the mandibular nerve - exits the skull through the foramen ovale of the mandible and innervates the skin of the lower cheek, lower lip, lower jaw and its teeth, chin, mucous membrane of the cheeks, lower part of the oral cavity, and tongue. The third branch also contains motor fibers that innervate the masticatory muscles.

Abducens nerve

VI pair - abducens nerve. Innervates the external rectus muscle of the eye, which moves the eyeball outward. The nerve nucleus is located in the posterior part of the pons at the bottom of the rhomboid fossa. The nerve fibers extend from the base of the brain to the border between the pons and the medulla oblongata. Through the superior orbital fissure, the nerve enters the cranial cavity into the orbit.

Facial nerve

VII pair - facial nerve. This is a motor nerve. Innervates facial muscles and muscles of the auricle. The nerve nucleus is located on the border between the pons and the medulla oblongata (Fig. 29). The nerve fibers leave the brain in the region of the cerebellopontine angle and, together with the vestibulocochlear nerve (VIII pair) (see Fig. 24), enter the internal auditory opening of the temporal bone and from there into the canal of the temporal bone, where this nerve goes along with the intermediate nerve (XIII pair). XIII nerve mixed. It carries sensory fibers of taste from the anterior 2/3 tongue and autonomic salivary fibers to the sublingual and submandibular salivary glands. In addition, in the canal of the temporal bone, along with the facial nerve, autonomic fibers also go to the lacrimal gland. This branch is the first to leave the facial nerve in the same canal of the temporal bone. Somewhat lower from the trunk of the facial nerve, a nerve departs that innervates the stapes muscle, located in the tympanic cavity of the ear. Shortly after this branch, the intermediate nerve itself departs from the facial nerve, after which the fibers of the facial nerve itself remain. They exit the skull through the stylopapillary foramen, dividing into terminal branches that innervate the facial muscles.

1 - bottom of the IV ventricle; 2 - nucleus of the facial nerve; 3 - facial nerve; 4 - stylomastoid foramen; 5 - branches of the facial nerve to the facial muscles and subcutaneous muscle of the neck; 6 - drum string; 7 - lingual nerve; 8 - pterygopalatine node; 9 - ternary node; 10 - internal carotid artery; 11 - intermediate nerve (XIII)

vestibulocochlear nerve

VIII pair - vestibulocochlear nerve. Nerve of special sensitivity. It consists of two independent sensory nerves - the cochlear (cochlear, actually auditory) and the vestibular.

1 - organ of Corti; 2 - spiral knot; 3 - auditory nerve; 4 - nuclei of the auditory nerve; 5 - side loop; 6 - lower colliculi of the quadrigeminal; 7 - medial geniculate body; 8 - cortical area of ​​the auditory analyzer (temporal lobe of the cortex)

The auditory nerve (Fig. 30) has a sensory node (spiral ganglion) located in the cochlea of ​​the labyrinth (inner ear). The peripheral processes of the first neurons begin from the spiral (Corti) organ, which is the perceptive device of the auditory pathway. The central processes of the cells of the spiral ganglion form the cochlear (cochlear) part, which emerges from the internal auditory opening of the temporal bone and enters the substance of the brain. These fibers end in the two nuclei of the auditory nerve located in the bridge. There are also a number of other nuclei that take part in the formation of further pathways for auditory stimulation. In the nuclei of the auditory nerves there are second neurons, the fibers from which, partially crossing, pass to the opposite side, and partially go along their own side, forming a so-called lateral loop, ending in the primary auditory centers - in the posterior tubercles of the quadrigeminal tuberosity and in the internal geniculate body of the optic tuberosity . The third neuron is located in the internal geniculate body. Fibers from it are directed through the internal capsule to the auditory region of the cerebral cortex (temporal lobe).

The vestibular nerve (vestibular) has a sensory node located in the internal auditory canal. The peripheral processes of the cells of this node approach the receptor cells in the semicircular canals of the inner ear. Their central processes are part of the vestibular nerve, which goes to its nuclei located in the tegmentum of the bridge. The most important functionally are the nuclei of Bekhterev and Deiters. There are second neurons there. The nuclei of the vestibular nerves are closely connected with the nuclei of the cerebellar vermis, the nuclei of the oculomotor nerves (via the posterior longitudinal fasciculus), with the optic thalamus and, through it, with the cerebral cortex, with the spinal cord, with the autonomic nuclei of the intermediate nerve.

The vestibular apparatus is an important organ of balance in the body. Relates to extrapyramidal innervation of movements.

Glossopharyngeal nerve

IX pair - glossopharyngeal nerve. This is a mixed nerve. It contains motor, sensory and autonomic (parasympathetic) fibers. The nerve has four nuclei: 1) the motor nucleus is common with the vagus nerve; 2) sensory nucleus - common with the vagus nerve; 3) sensitive taste nucleus - common with the intermediate nerve; 4) the autonomic secretory nucleus for the parotid salivary gland - common with the intermediate nerve.

The nuclei are located in the medulla oblongata. The glossopharyngeal nerve appears on the inferior surface of the brain behind the vestibulocochlear nerve. It exits the skull through the jugular foramen. Has two sensitive nodes. These nodes contain the first neurons for sensitive innervation of the mucous membrane of the upper half of the pharynx, uvula, and soft palate. The second neurons lie in the sensory nucleus common with the vagus nerve. Beginning in the mucous membrane of the posterior third of the tongue, taste sensory fibers conduct taste stimuli through the peripheral nodes to the taste nucleus, which is common with the intermediate nerve. sensory fibers of which conduct taste stimulation from the anterior 2/3 of the tongue.

The motor fibers of the glossopharyngeal nerve innervate the muscles of the pharynx, uvula, and soft palate (together with the vagus nerve). Promote the act of swallowing and articulation.

Secretory autonomic fibers, starting from the corresponding nucleus, common with the intermediate nerve, innervate the parotid gland. The branches of the intermediate nerve innervate the sublingual and submandibular salivary glands.

Vagus nerve

X pair - vagus nerve. This is a mixed nerve. Provides sensitive innervation to the meninges, external auditory canal, pharynx, larynx, trachea, bronchi, lungs, gastrointestinal tract and other abdominal organs. The motor fibers of the nerve innervate the muscles of the pharynx, soft palate (together with the glossopharyngeal nerve), larynx, epiglottis, involuntary muscles of the trachea and bronchi, esophagus, stomach, and intestines. In addition, this nerve contains secretory fibers going to the stomach and pancreas, fibers that inhibit the heart, fibers going to the blood vessels. The nerve has a sensory and motor nucleus (common with the glossopharyngeal nerve), and an autonomic nucleus for innervation of internal organs.

Thus, the function of the vagus and glossopharyngeal nerves is very important in life. They innervate the muscles of the pharynx (provide the act of swallowing), larynx, epiglottis, and soft palate (provide phonation and articulation). The vagus nerve is a conductor of sensations coming from the internal organs, provides sensitivity to the entire respiratory and most digestive tract. The branches of the vagus nerve are even more important in regulating the cough and gag reflexes. The vagus nerve plays a huge role in regulating the activity of the heart, breathing, stomach, and intestines. This nerve is also of great importance in regulating the tone of blood vessels.

Accessory nerve

XI pair - accessory nerve. This is a motor nerve. The cells that give rise to this nerve are located in a long nucleus located in the gray matter of the spinal cord (in its upper cervical segments). The nerve roots (6-7 of them) emerge on the lateral surface of the spinal cord, unite into one trunk, then enter through the foramen magnum into the cranial cavity, from there through the jugular foramen the nerve exits the cranial cavity and innervates the sternocleidomastoid and trapezius muscles.

The function of the sternocleidomastoid muscle is to tilt the head to one side and turn it in the opposite direction; The function of the trapezius muscle is to elevate the shoulder, abduct the shoulder girdle posteriorly, and adduct the scapula toward the spine.

Hypoglossal nerve

XII pair - hypoglossal nerve. This is a motor nerve that innervates the muscles of the tongue. The nerve nucleus is located at the bottom of the rhomboid fossa. The nerve roots (there are 10-15 of them) come out of medulla oblongata along its lateral surface and are connected into one stem; this stem exits the cranial cavity through the canal of the hypoglossal nerve.

7. VII pair of cranial nerves - facial nerve

It is mixed. The motor pathway of the nerve is two-neuron. The central neuron is located in the cerebral cortex, in the lower third of the precentral gyrus. The axons of the central neurons are sent to the nucleus of the facial nerve, located on the opposite side in the pons, where the peripheral neurons of the motor pathway are located. The axons of these neurons make up the root of the facial nerve. The facial nerve, passing through the internal auditory foramen, goes to the pyramid of the temporal bone, located in the facial canal. The nerve then leaves the temporal bone through the stylomastoid foramen, entering the parotid salivary gland. In the thickness of the salivary gland, the nerve is divided into five branches, forming the parotid nerve plexus.

The motor fibers of the VII pair of cranial nerves innervate the facial muscles, the stapedius muscle, the muscles of the auricle, the skull, the subcutaneous muscle of the neck, and the digastric muscle (its posterior abdomen). In the facial canal of the pyramid of the temporal bone, three branches depart from the facial nerve: the greater petrosal nerve, the stapedial nerve, and the chorda tympani.

The greater petrosal nerve passes through the pterygopalatine canal and ends at the pterygopalatine ganglion. This nerve innervates the lacrimal gland by forming an anastomosis with the lacrimal nerve after interruption in the pterygopalatine ganglion. The greater petrosal nerve contains parasympathetic fibers. The stapedius nerve innervates the stapedius muscle, causing its tension, which creates conditions for the formation of better audibility.

The chorda tympani innervates the anterior 2/3 of the tongue, responsible for transmitting impulses during a variety of taste stimuli. In addition, the chorda tympani provides parasympathetic innervation to the sublingual and submandibular salivary glands.

Symptoms of defeat. When motor fibers are damaged, peripheral paralysis of the facial muscles on the affected side develops, which is manifested by facial asymmetry: half of the face on the side of the affected nerve becomes motionless, mask-like, the frontal and nasolabial folds are smoothed, the eye on the affected side does not close, the palpebral fissure widens, the corner of the mouth is lowered down .

Bell's phenomenon is noted - an upward rotation of the eyeball when attempting to close the eye on the affected side. Paralytic lacrimation is observed due to lack of blinking. Isolated paralysis of the facial muscles is characteristic of damage to the motor nucleus of the facial nerve. If a lesion of the radicular fibers is added to the clinical symptoms, Millard-Hübler syndrome (central paralysis of the limbs on the side opposite to the lesion) is added.

When the facial nerve is damaged in the cerebellopontine angle, in addition to paralysis of the facial muscles, decreased hearing or deafness and absence of the corneal reflex are observed, which indicates simultaneous damage to the auditory and trigeminal nerves. This pathology occurs with inflammation of the cerebellopontine angle (arachnoiditis), acoustic neuroma. The addition of hyperacusis and taste disturbance indicate damage to the nerve before the greater petrosal nerve departs from it in the facial canal of the pyramid of the temporal bone.

Damage to the nerve above the chorda tympani, but below the origin of the stapedial nerve is characterized by taste disorder and lacrimation.

Paralysis of facial muscles in combination with lacrimation occurs when the facial nerve is damaged below the origin of the chorda tympani. Only the cortical-nuclear pathway may be affected. Clinically, paralysis of the muscles of the lower half of the face on the opposite side is observed. Often paralysis is accompanied by hemiplegia or hemiparesis on the affected side.

From the book Nervous Diseases by M. V. Drozdov

50. Damage to the first and second pairs of cranial nerves. The pathway of the olfactory nerve consists of three neurons. The first neuron has two types of processes: dendrites and axons. The endings of the dendrites form olfactory receptors located in the mucous membrane of the nasal cavity.

From the book Nervous Diseases: Lecture Notes author A. A. Drozdov

51. Damage to the III and IV pairs of cranial nerves. The nerve pathway is two-neuron. The central neuron is located in the cells of the cortex of the precentral gyrus of the brain. The axons of the first neurons form the cortical-nuclear pathway, heading to the nuclei of the oculomotor

From the author's book

53. Damage to the VI pair of cranial nerves Damage to the VI pair of cranial nerves is clinically characterized by the appearance of convergent strabismus. A characteristic complaint of patients is double image, located in the horizontal plane. Joins often

From the author's book

55. Lesions of the IX–X pairs of cranial nerves IX–X pairs of cranial nerves are mixed. The sensitive nerve pathway is three-neural. The cell bodies of the first neuron are located in the ganglia of the glossopharyngeal nerve. Their dendrites end in receptors in the posterior third of the tongue, the soft

From the author's book

56. Lesions of the XI–XII pair of cranial nerves. It consists of two parts: the vagus and the spinal nerves. The motor pathway is two-neuron. The first neuron is located in the lower part of the precentral gyrus. Its axons enter the cerebral peduncle, pons, oblongata

From the author's book

1. I pair of cranial nerves - olfactory nerve The pathway of the olfactory nerve consists of three neurons. The first neuron has two types of processes: dendrites and axons. The endings of the dendrites form olfactory receptors located in the mucous membrane of the cavity

From the author's book

2. II pair of cranial nerves - optic nerve The first three neurons of the visual pathway are located in the retina. The first neuron is represented by rods and cones. Second neurons are bipolar cells. Ganglion cells are third neurons.

From the author's book

3. III pair of cranial nerves - oculomotor nerve The nerve pathway is two-neuron. The central neuron is located in the cells of the cortex of the precentral gyrus of the brain. The axons of the first neurons form a cortical-nuclear path leading to the nuclei

From the author's book

4. IV pair of cranial nerves - trochlear nerve The pathway is two-neuron. The central neuron is located in the cortex of the lower part of the precentral gyrus. The axons of the central neurons end in the cells of the nucleus of the trochlear nerve on both sides. The nucleus is located in

From the author's book

5. V pair of cranial nerves - trigeminal nerve It is mixed. The sensory pathway of a nerve consists of neurons. The first neuron is located in the semilunar ganglion of the trigeminal nerve, located between the layers of the dura mater on the anterior surface

From the author's book

6. VI pair of cranial nerves – abducens nerve The pathway is two-neuron. The central neuron is located in the lower cortex of the precentral gyrus. Their axons end on the cells of the nucleus of the abducens nerve on both sides, which are peripheral

From the author's book

8. VIII pair of cranial nerves - vestibular-cochlear nerve The nerve consists of two roots: the cochlear, which is the lower, and the vestibular, which is the upper root. The cochlear part of the nerve is sensitive, auditory. It starts from the cells of the spiral ganglion, in

From the author's book

9. IX pair of cranial nerves - glossopharyngeal nerve This nerve is mixed. The sensory nerve pathway is three-neuron. The cell bodies of the first neuron are located in the ganglia of the glossopharyngeal nerve. Their dendrites end in receptors in the posterior third of the tongue, the soft

From the author's book

10. X pair of cranial nerves - vagus nerve It is mixed. The sensitive pathway is three-neuron. The first neurons form the nodes of the vagus nerve. Their dendrites end in receptors on the dura mater of the posterior cranial fossa,

From the author's book

11. XI pair of cranial nerves - accessory nerve It consists of two parts: the vagus and the spinal nerve. The motor pathway is two-neuron. The first neuron is located in the lower part of the precentral gyrus. Its axons enter the cerebral peduncle, pons,

From the author's book

12. XII pair of cranial nerves - hypoglossal nerve For the most part, the nerve is motor, but it also contains a small part of the sensory fibers of the lingual nerve branch. The motor pathway is two-neuron. The central neuron is located in the inferior cortex

cranial nerves(lat. Nervi craniales)- nerves that begin directly in the brain. Most anatomy textbooks indicate that humans have twelve pairs of cranial nerves, although including the terminal nerve, humans have thirteen pairs of cranial nerves: the first three arise from the forebrain, the remaining ten from the brainstem. In other vertebrates, the number of cranial nerves varies.

13 pairs of cranial nerves (12 classical pairs and a pair of terminal nerves), together with 31 pairs of spinal nerves, make up the peripheral nervous system.

Cranial nerves are designated by Roman numerals from most rostral to most caudal, and each has its own name reflecting its location or function.

All cranial nerves, except the vagus, innervate the head and neck. The vagus nerve also innervates the organs of the thoracic and abdominal cavities. When cranial nerves are damaged, the functions they provide deteriorate or disappear.

General principles of structure and functioning

It is incorrect to consider the cranial nerve in the context of the nerve trunk alone. The cranial nerve is a system that consists of the nerve itself and nuclei, nodes, nerve tracts, columns in the medulla oblongata, cortical and subcortical analyzers that are connected to this nerve.

Cores

The nucleus is a collection of neurons that are compactly located among the white matter. Each set of neurons performs specific functions, that is, motor nuclei (consisting of motor neurons that innervate muscles), sensory nuclei (mainly the second neurons of the sensory nerve pathway) and autonomic nuclei (in the context of cranial nerves - parasympathetic, they can also be classified as motor nuclei - visceromotor nuclei). With the exception of the optic, olfactory and terminal nerves, each nerve has one or more nuclei. All nuclei are also paired formations (except for the debatable nucleus of Perlia, which belongs to the third pair of cranial nerves).:

Nerve	Sensitive core	Motor core	Vegetative nucleus	Images
III	—	Oculomotor nerve nucleus	Edinger-Westphal nucleus (Yakubovich nucleus) Perlian nucleus (considered in two ways: as part of the Edinger-Westphal nucleus, and as an independent nucleus)	Schematic representation of cranial nerve nuclei with fibers entering or exiting them (the serial number corresponds to the nerve)
IV	—	Trochlear nerve nucleus	—
V	Main nucleus of the trigeminal nerve spinal nucleus of the trigeminal nerve Serococervical nucleus of the trigeminal nerve	Motor nucleus of the trigeminal nerve	—
VI	—	Abducens nerve nucleus	—
VII	Lonely Path Core	Facial nerve nucleus	Superior salivary nucleus
VIII	Curl nucleus vestibular nuclei	—	—
IX	Lonely Path Core	Dual core	Inferior salivary nucleus
X	Lonely Path Core	Dual core	Posterior nucleus of the vagus nerve
XI	—	Posterior nucleus of the vagus Nucleus ambiguus	—
XII	—	Hypoglossal nerve nucleus	—

Also, the lateral line nerves have nuclei, but their number and type vary among species. In some animal species, the number of nerve nuclei that are present may differ in humans (for example, the lateral trigeminal nucleus in snakes of the family Boidae is additional to the trigeminal nerve).

Nodes

The node is a homolog of the nucleus, which is located outside the central nervous system.

The cranial nerves are connected to two types of ganglia - sensory and autonomic. The first are available only when the nerve includes fibers of general or special sensitivity, the second - when there are parasympathetic fibers:

• Sensitive:
  • The terminal node is a sensory node belonging to the nerve of the same name
  • Trigeminal ganglion - contains the primary neurons in the trigeminal nerve system
  • Cochlear ganglion - connected to the helix (hearing) part of the helix-parynx nerve
  • Vestibular ganglion - connected to the vestibular (balance) part of the helix-prisyncra nerve
  • The geniculate ganglion is connected to the facial (more precisely, the intermediate) nerve
  • The superior (jugular) and inferior (petrosal) nodes of the hypoglossal nerve
  • Superior (jugular) and inferior (nodular) ganglia of the vagus nerve
• The cranial nerves are connected to four vegetative head nodes:
  • The pterygopalatine ganglion - its sensory branch is formed by the trigeminal nerve, and the parasympathetic branch is formed by the facial nerve
  • The auricular node is a sensitive branch formed by the trigeminal nerve, the parasympathetic branch is formed by the glossopharyngeal nerve
  • The submandibular ganglion is a sensitive branch formed by the trigeminal nerve, the parasympathetic branch is formed by the facial nerve
  • The ciliary ganglion is a sensory branch formed by the trigeminal nerve, the parasympathetic branch is formed by the oculomotor nerve.
  • The vagus nerve is connected to a large number of intramural parasympathetic ganglia in the abdominal and thoracic cavities.

Anatomy in the Brainstem and Types of Information

Not all nerve components have separate nuclei. For example, the VII, IX and X pairs of cranial nerves carry sensory taste fibers, but they end in one nucleus - the nucleus of the solitary tract. The same is with the trigeminal nuclei, to which all superficial and deep sensory information follows, and the double nucleus, which is common to the three nerves. In addition, the topical motor nuclei with the fibers that are directed to them are located quite rectilinearly, forming “pillars”. The same goes for sensitive cores. In addition, these pillars are similar in organization to the horns of the spinal cord, and also indicate the embryonic development of the nerve components (sensory pillars are located dorsally and arise from the alar plate of the neural tube, and motor pillars are located ventrally and develop from the plate of the same name).

So, depending on the information, there are four columns of nuclei and their neurons, which correspond to four main types of information (two sensitive (afferent) and two motor (efferent)):

• Sensitive information may be:
  • general somatic general somatic afferents (GSA))- the column is formed by the trigeminal nuclei and perceives tactile, pain and temperature information (fibers V, VII, IX and X pairs of nerves are directed to these nuclei)
  • general visceral general visceral afferents (GVA))- a column formed by the nucleus of the solitary tract, perceives sensitive information from the organs of the neck, chest cavity, abdomen, parotid gland (fibers of the IX and X pairs of nerves)
• In addition to these two main types of information, which are also characteristic of the spinal nerves, two more are distinguished for the cranial nerves: special sensitive types of information:
  • special visceral special visceral afferents (SVA))- part of the solitary tract nucleus that perceives taste (the so-called “taste nucleus”); fibers are sent from VII, IX and X pairs of nerves
  • special somatic special somatic afferents (SSA))- the column is formed by the vestibular and helical nuclei, associated with the VIII pair (and in animals with the lateral line - with the nerves that innervate it)

There are several nuances associated with the classification of information. First, specific and general information did not differ in the way they were analyzed or produced. This is an artificial division that has developed historically. Secondly, such sensations as vision and smell are also classified as special sensitive (although there are no nuclei in the nerves that provide these senses).

• Motor information can be:
  • general visceromotor general visceral efferents (GVE))- a column formed by all parasympathetic nuclei (III, VII, IX and X pair of nerves) and innervates the organs of the head, neck, chest, abdominal cavity (saliva secretion, slow heartbeat, bronchospasm, etc.)
  • general somatomotor general somatic efferent (GSE))- a column that innervates the muscles formed from the somites and is supplied by the perioral nerves and the hypoglossal nerve
• As in the case of afferent columns There is special efferent information:
  • special visceromotor (brachiomotor) special visceral efferent (SVE))- provides innervation to the muscles formed from the pharyngeal arches (masticatory, facial, throat muscles) nerves that carry such information - V, VII, IX and X.

Special motor innervation does not differ in essence from general innervation; this division was also formed artificially and historically.

Similarities and differences with spinal nerves

Spinal nerves are nerves that arise directly from the spinal cord. There are a number of features that are common to both them and cranial ones; There are a number of signs that are excellent. Thus, cranial nerves are more specialized: if all spinal nerves carry all possible types information into its segment of innervation, then not all cranial nerves have both motor, sensory, and autonomic components. The posterior branch of the spinal nerve is associated with the sensory ganglion; The same is true for sensory (general sensitivity) nerves. The similarity of the exit of the nerves is preserved: the motor cranial nerves contain their nuclei ventrally, the sensory ones dorsally; in the spinal nerves, the motor root exits in front, the sensory root exits behind. Spinal nerves innervate the body with a segmental type; The segmentarism of the chairman is still within the scope of the discussion.

Embryogenesis

During the development of the neural tube (a derivative of the ectoderm, from which the entire central nervous system is subsequently formed), its lateral plate is divided into the anterior (basal) plate, from which motor components can arise, and the posterior (alarna, Krylov), from which sensory components can arise. Thus, the motor (somato- and viscero-) nuclei arise in the anterior plate, and the sensory ones - in the posterior plate.

The brain is formed from the rostral part of the neural tube, first passing through the stage of three primary and five secondary vesicles. Each primary vesicle consists of a certain number of neuromeres. The nuclei of cranial nerves IV-XII are formed in the rhombencephalon (lat. Rhombencephalon)), in eight available rhombometers. Only the nuclei of the oculomotor nerves are formed in the midbrain (lat. Mesencephalon), in mesomers.

Sensitive and autonomic ganglia of cranial nerves are formed from the neural crest and neural placodes (sensitive ganglia are formed from both neural crest cells and placode cells; autonomic ganglia are formed only from the neural crest). There are a nasal placode, ventrolateral or epibrachial, a group that includes sensory placodes that form the sensory nodes of the nerves of the pharyngeal arches (all except the trigeminal nerve) and a dorsolateral group of placodes, which includes the auricular placode, (in the anamnium) placodes of the lateral line, trigeminal and deep placode. In some animals (spur frog, salamanders, certain species of fish), the deep placode gives rise to the deep ganglion, which innervates the upper third of the face, and the nerve of this ganglion does not connect with the trigeminal nerve. In other animals, to a greater or lesser extent, the placodes merge and form one tripartite placode, the predecessor of the trigeminal ganglion, and the nerve of this placode turns into optic nerve.

Motor branches associated with somites, somitomeres and pharyngeal arches. Somites and somitomeres are derivatives of mesoderm. The mesoderm consists of three parts: the dorsal part, which is called the paraaxial mesoderm (epimere), and from which the muscles of the head are formed, which are not associated with the pharyngeal arches (oculomotor and tongue muscles); mesomere, with which the cranial nerves are not connected in any way; hypomeres, from which the muscles associated with the pharyngeal arches develop. The III, IV, VI and XII pairs of cranial nerves are connected to the oculomotor nerves and the muscles of the tongue.

The gill (pharyngeal) arch is an embryonic formation consisting of mesenchyme, externally covered with ectoderm, and internally with endoderm. There are five pharyngeal arches; the nerve that is connected to it innervates its derivatives:

The optic nerve develops as a process of the forebrain (namely, the diencephalon, lat. Diencephalon). The olfactory nerve and (present in some animals) Jacobson's nerve develop from the olfactory placode, but are strongly connected to the telencephalon (lat. Telencephalon), Therefore, how to grow it is considered.

Classification

So, depending on embryonic development, anatomical structure, functions, topography, there are many classifications of cranial nerves.

First of all, a distinction is made between real and fake cranial nerves - I and II, which develop as the brain grows to the periphery. Their myelin (central type) also differs from the myelin of other nerves (peripheral type), which explains the frequent involvement of these nerves in the pathological process in multiple sclerosis. These nerves are functionally sensitive.

Functionally, real nerves are divided into three large groups:

• motor (contain only somatomotor and visceromotor fibers) - III, IV, VI, XI and XII pairs of cranial nerves
• sensitive (contain only sensory fibers) - VIII pair of cranial nerves
• mixed (contain fibers of both types) - V, VII, IX and X pairs of cranial nerves

Topical nerves are divided into:

• forebrain nerves - 0, I and II pair of nerves
• midbrain nerves - III and IV pairs of nerves
• pons nerves - V, VI, VII and VII pairs of nerves
• nerves of the medulla oblongata (bulbar) - IX, X, XI and XII pairs of nerves

Clinically, nerves (real) are divided into:

• oculomotor nerves - III, IV and VI pairs of nerves
• nerves of the cerebellopontine angle - V, VI, VII and VII pairs of nerves
• caudal nerves - IX, X, XI and XII pairs of nerves

Embryologically, there is such a division of nerves:

• nerves of the pharyngeal arches - V, VII, IX, X and XI pairs of nerves
• nerves associated with somites - III, IV and VI pairs of nerves
• nerves associated with myotomes - XII pair of cranial nerves

According to the false nerves, they are considered outgrowths of the forebrain. However, they still of different origins: olfactory - develops from placodes, and visual is a continuation of the brain. Both the VIII (true) pair of nerves and the lateral line nerves develop from the placodes. The second pair and the epiphyseal nerve are true outgrowths of the diencephalon.

The above functional classification is traditional. Also created new classification, in which there is no concern of nerves for special and general innervation. This classification also takes into account the embryonic origin of the nerve for each component (both sensory and motor): the optic nerve is considered to be a derivative of the neural tube, the terminal nerve is a derivative of the neural crest, the sensitive part of the trigeminal is formed from the crest and placodes; somatosensory parts of the VII, IX and X nerves - from the crest; fibers that provide sensitivity to internal organs (fibers of the IX and X nerves) - also from the neural crest; taste component VII, IX and X - from placodes; somatomotor and visceromotor components - from the neural tube (basal plate).

Comparative anatomy

Twelve pairs of cranial nerves is a classic concept, and one that primarily concerns humans. In humans and other amniotes there is a thirteenth nerve - terminal. There is an ongoing debate about the separation of the intermediate nerve into a separate nerve. During embryonic development, humans have a vomeronasal nerve, which is subsequently reduced. Some amniotes have an epiphyseal nerve.

The anamny also more cranial nerves. In addition to the twelve classical nerves, the terminal and well-developed epiphyseal nerves, aquatic amniotes have lateral line nerves, the number of which can reach six.

Joint nerves

Among the “canonical” twelve pairs of cranial nerves, ten corresponding ones are found in the anamnia (the XI pair is a component of the X pair, there is no XII pair, there are only its homologues - branches of the vagus nerve). The remaining ten pairs have only some minor modifications. Some amniotes have an epiphyseal nerve. Thus, salamanders have a separate deep ophthalmic nerve (in most animals it, together with its ganglion, is united with the first branch of the trigeminal nerve). Sharks have a fourth branch of the trigeminal nerve, the superficial ophthalmic nerve.

Minor modifications associated with the oculomotor muscles, the number of which differs between species and classes. In most cases, the III pair innervates the medial, inferior and superior rectus muscles and the superior inferior oblique muscle. The IV pair innervates the superior oblique muscle. The VI pair innervates the external rectus muscle. Hagfish lack eye muscles, and moray eels lack the medial rectus muscle - this affects the number and function of nerves. In addition to the eyes, these nerves are responsible for the movements of the eyelids. Usually, only the upper eyelid can move, but in the anamnesis both move: the upper one is innervated by the third pair of cranial nerves, and the lower one by the V (trigeminal nerve). Amphibians, birds, reptiles and some mammals (hares) have a “third” eyelid. In lizards and birds, it is innervated by the VI pair (the main nerve, innervates the retractor muscle of the eyeball) and the III pair (additional, innervates the quadratus muscle). In crocodiles and turtles, the III nerve is also auxiliary, but innervates another muscle (pyramidal).

Another modification is associated with carp and catfish. They have a very developed taste system: not only the oral cavity, but their entire body is covered with taste buds. In addition, these fish filter the water in search of food, so they need a good taste. That is why the taste kernel (lat. Nucleus gustatorius)(part of the core of the lonely path) in them is a voluminous and large formation. The part that belongs to the vagus nerve is called the vagus lobe, and the part that belongs to the facial nerve is called the facial nerve.

These are not the only modifications with the number of nuclei and their function: snakes have a trifoliate nucleus, which receives information from the infrared organ.

Another convoluted nerve

In addition to the optic nerve, in many vertebrates there is another vitlosprimal nerve. In English literature it is called epiphyseal nerve(translated as epiphyseal nerve) and goes to the epiphysis. There is no corresponding Ukrainian deadline yet. However, this switch is not used for visual analysis in the central nervous system, but provides regulation of circadian rhythms.

The nerve consists of unmyelinated fibers and is ontogenetically very similar to the optic nerve, that is, it is also a process of the forebrain to the periphery. That is why many authors do not consider it a nerve, but only a nerve pathway.

This nerve can be divided into two others: pineal nerve and actually epiphyseal nerve The division depends on the structure of the pineal gland: in some animals, in addition to the pineal gland, there is also a photosensitive paripineal organ (“third eye”). Most lampreys, some bony fishes, some tailless amphibians and some reptiles (many lizards and hatteria) have both parts, so they have two nerves. In other anamnia and reptiles, only one part is accessible, so there is only one nerve in them (however, in hagfish and crocodiles, it, like the pineal gland, is absent altogether). In birds and mammals the nerve is either greatly reduced or absent.

Lateral line nerves

In addition to the senses common to all vertebral organs, the anamnesis also includes the lateral line, which provides electroreception and mechanoreception, which allows for better orientation in aquatic environment. The lateral line nervous apparatus consists of lateral line nerves, whose dendrites end in neuromasts - mechanical receptors of the lateral line - and ampullary or Gorbkoff receptors (these are electroreceptors of the lateral line).

Usually there are six of these nerves and they are divided into two groups: the anterior (located between the trigeminal and facial nerves) and the pislavicular (located between the glossopharyngeal and vagus nerves). The first group includes the anteroposterior lateral line nerve, the posteroposterior lateral line nerve and the lateral line auricular nerve. The second group includes the middle nerve of the lateral line, the supracroneal nerve of the lateral line and the posterior nerve of the lateral line. Some animals, such as the Ambystos, lack the auricular nerve.

In addition to communicating with receptors, the nerves give communicative branches to other nerves: the ophthalmic and buccal branches of the posteroposterior nerve to the first two branches of the trigeminal nerve, the anteroposterior nerve together with the facial nerve forms the hypoglossal-mandibular trunk.

The central endings of the nerves are directed to the cerebellum and to the sensory nuclei of the medulla oblongata. Next, the fibers are directed as part of the lateral lemniscus, which in bony fishes ends in the semilunar ridge, and in different sharks - in the lateral mesencephalic nucleus or lateral mesencephalic complex.

Vomeronasal nerve

The vomeronasal (lemish-nasal) nerve, or Jacobson's nerve, is a nerve that innervates the organ of the same name (Jacobson's organ). It is present only in some tetrapods (best developed in squamates (Squamosa), among mammals - in mouse-like). In humans it is present only during embryonic development. Absent in crocodiles, birds, and most mammals. The nerve is closely related to the olfactory nerve both anatomically and functionally. Its fibers are directed to the additional olfactory bulb.

Human anatomy

List of human cranial nerves and their functions

In humans, like other amniotes, there are thirteen pairs of cranial nerves - twelve “classical” and a terminal nerve:

Nerve name	Sensory/Motor fibers	Path	Function
0, N Terminal (lat. Nervus terminalis)	Sensitive	Starts from the nasal septum and goes to the terminal plate of the brain (the terminal branching of the nerve is a variable sign for different classes)	The function is not fully understood; thought to be responsible for the perception of pheromones and thus influence sexual behavior
I Olfactory (lat. Nervus olfactorius)	Sensitive	Begins with the olfactory receptors of the nose, nerve fibers through the openings in the ethmoid bone rise to the olfactory bulbs, from where the olfactory tract begins, passes to the primary olfactory cortex, which is contained in the telencephalon.	Transmission of information from olfactory receptors.
II Visual (lat. Nervus opticus)	Sensitive	Beginning in the retina, bundles of fibers from each eye are directed to the brain, where they partially intersect, forming the optic chiasm, and continue as the optic tract to the thalamus. From the thalamus begins the visual radiance, consisting of fibers directed to the primary visual cortex in the occipital lobe of the hemispheres.	Transmission of information from rods and cones, that is, ensuring the function of vision
III Oculomotor (lat. Nervus oculomotorius)	Motor	It begins in the ventral part of the midbrain, passes through the superior orbital fissure, after which it branches into several branches that innervate the oculomotor (except for the superior oblique and lateral rectus) muscles.	Somatic motor fibers innervate four muscles that provide eye movement: the inferior oblique, inferior, medial and superior rectus. Parasympathetic motor fibers innervate the pupillary sphincter and ciliary muscles and regulate the convexity of the lens.
IV Block (lat. Nervus trochlearis)	Motor	It begins in the dorsal part (the only nerve that exits from the back, on the posterior surface of the brain stem) of the midbrain, goes forward to the superior orbital fissure, through which it passes along with the oculomotor nerve.	Somatic motor fibers innervate the superior oblique muscle of the eye.
V Trigeminal (lat. Nervus trigeminus)		The nerve exits with two roots in front of the middle cerebellar peduncle; goes to the sensitive trigeminal ganglion, which itself forms a sensitive root with its axons; motor and proprioceptive fibers transit the node; Before leaving the skull, the trunk is divided into three branches:
Optic nerve (V 1) (lat. Nervus ophthalmicus)- dendrites pass through the superior palpebral fissure and are directed to the frontal region, eyeball, lacrimal gland, ethmoid bone and part of its elements - parts of the nasal cavity.	Relays sensory information from the upper face, upper eyelids, nose, nasal mucosa, cornea and lacrimal glands.
Maxillary nerve (V 2) (lat. Nervus maxillaris)- dendrites pass through the foramen rotundum and exit into the pterygopalatine fossa.	Transmits sensory information from the mucous membrane of the nasal cavity, larynx, upper teeth, upper lip, cheeks, lower eyelids.
Mandibular nerve (V 3) (lat. Nervus mandibularis)— the dendrites of sensory neurons and the axons of motor neurons together form one trunk, which passes through the oval foramen of the sphenoid bone.	Transmits sensory information from the lower part of the face, chin, front of the tongue (except taste buds), lower teeth. Motor fibers innervate the masticatory muscles.
VI Abductor (lat. Nervus abducens)	Motor	Passes from the lower part of the bridge (on the border with the pyramid of the medulla oblongata) to the eye through the superior orbital fissure.	Contains somatic motor fibers innervating the lateral rectus muscle of the eye.
VII Facial (lat. Nervus facialis)(it includes the intermediate nerve (lat. Nervus intermedius))	Sensory and motor	It departs from the cerebellopontine angle, enters the temporal bone through the internal auditory canal, passes some distance inside the bone, where the greater petrosal, stapedial nerves and chorda tympani gradually leave it; terminal (before the facial muscles) branches exit through the stylomastoid foramen.	Somatic motor fibers innervate the facial muscles, motor fibers of the parasympathetic nervous system innervate the lacrimal glands, glands of the nasal cavity and palate, submandibular and sublingual salivary glands. Sensory fibers transmit information from the taste buds of the two anterior thirds of the tongue.
VIII vestibular-cochlear (lat. Nervus vestibulocochlearis)	Sensory and motor	Vestibular and cochlear nerves start from the hair cells of the balance apparatus and hearing aid the inner ear, respectively, pass through the internal auditory canal, merge into one vestibulocochlear nerve, which enters the brain at the border between the pons and the medulla oblongata.	Transmits sensory information from the organs of hearing and balance.
IX tongue-pharyngeal (lat. Nervus glossopharyngeus)	Sensory and motor	It starts from the medulla oblongata and goes through the jugular foramen to the throat, posterior third of the tongue, carotid sinus and salivary gland.	Somatic motor fibers innervate the upper pharyngeal muscles, parasympathetic efferent fibers innervate the parotid salivary glands. Sensory fibers transmit information from taste buds And general feelings(touch, pressure, pain) from the pharynx and posterior third of the tongue, chemoreceptors of the carotid body and baroreceptors of the carotid sinus.
X Wandering (lat. Nervus vagus)	Sensory and motor	It begins in the medulla oblongata, exits the skull through the jugular foramen, after which its branches branch into the neck, throat, and torso. The only one of the cranial nerves that extends beyond the head and neck.	Somatic motor fibers innervate the muscles of the pharynx and larynx, most efferent fibers are parasympathetic, they transmit nerve impulses to the heart, lungs and abdominal organs. Sensitive fibers carry information from the abdominal and thoracic organs, baroreceptors of the aortic arch, chemoreceptors of the carotid and aortic bodies, and taste buds of the back of the tongue.
XI Additional (lat. Nervus accessorius)	Motor	Formed by two roots: cranial, which extends from the medulla oblongata, and spinal, which extends from the upper part (C 1 -C 5) of the spinal cord. The spinal root enters the skull through the foramen magnum, unites with the cranial nerve into a single accessory nerve, which, after leaving the skull through the jugular foramen, again divides into two branches: the cranial one joins the vagus nerve, and the spinal root innervates the muscles of the neck.	The cranial branch innervates the muscles of the pharynx, larynx and soft palate, the spinal branch innervates the trapezius and sternocleidomastoid.
XII Sublingual (lat. Nervus hypoglossus)	Motor	It begins with a number of roots in the medulla oblongata, leaves the skull through the canal of the hypoglossal nerve and goes to the tongue.	Innervates the muscles of the tongue, which ensure mixing of food, swallowing and the formation of sounds during speech.
Sensory proprioceptor fibers are not taken into account (contained in all motor (muscle-related) nerves) This refers to the nerve trunk, not the pathways to the central nervous system

Paths

The general structure of the pathways for cranial nerves is as follows:

• for sensory nerves (or mixed nerves containing sensory fibers):
  • The first neuron is contained in the sensory node (the only exception is for the proprioceptive fibers of the trigeminal nerve, which go directly to the central nervous system)
  • The second neuron is located in the brain stem
  • The third neuron is contained in the anterior nucleus of the anterior pubic group of the thalamus

Neurons in the thalamus mainly send their axons to the central gyrus of the telencephalon

• for the somatomotor component (the name of the path is cortical-nuclear (lat. tractus corticonuclearis)):
  • the first neuron is located in the precentral gyrus of the telencephalon
  • the second neuron is a neuron of one of the motor nuclei

• The visceromotor component is characterized by the following path:
  • the first neuron is a neuron of the autonomic nucleus of the brainstem
  • the second neuron is the neuron of the vegetative node.

Blood supply

The blood supply to the cranial nerves is variable, because their vascularization provides small vessels, arising from the branches of the three main arteries of the head - the internal carotid artery, the external carotid artery and the basilar artery - while in different individuals, branches from different large vessels may depart to the same nerve. Most often, the olfactory nerve is supplied with blood from the olfactory artery, which arises from the A2 segment of the anterior cerebral artery. The optic nerve is bleeding along almost its entire length from the exit from the brain by the central retinal artery, and only the terminal section is bleeding by short ciliary arteries. The group of oculomotor nerves (III, IV and VI) in the initial sections are supplied with blood from the vertebrobasilar basin, and the part that goes to the cavernous sinuses is supplied from the internal carotid artery basin. The trigeminal nerve in the initial section can be vascularized both due to the trigeminal artery or another branch from the cerebellar or basilar artery, and thanks to the meningeal-hyoid artery (basin of the internal carotid artery), and a branch from the ascending pharyngeal artery (external carotid artery). The terminal branches are supplied with blood from the basin of both carotid arteries. The facial nerve is approached by branches from the anterior inferior cerebellar or labyrinthine arteries (basilar basin), or from the middle meningeal artery (external carotid artery). The terminal branches are supplied with blood from the arteries located next to them. The vestibulocochlear nerve is supplied by the same arteries as the facial one. The bulbar group (IX, X, XI and XII) feeds mainly from the branches of the basilar artery, although quite often from the external carotid artery.

Clinic

Examination and symptoms

Each nerve has a specific function that is tested to determine whether the nerve is functioning properly and whether there is any damage. Testing is performed in an order that corresponds to the cranial nerve number. If a disorder is found, it is differentiated from all possible ones, which, however, are associated with damage to other parts of the nervous system. Below are tests for each nerve:

• Since the olfactory nerve is responsible for the perception of odors, to test it the patient is asked to close one nostril, and a stimulus (smell) is presented in the other. The patient must indicate what smell he smells. Do not use substances such as ammonia or gasoline. Disorders that can be found are anosmia (loss of smell), hyposmia (decreased sense of smell), hyperosmia (increased sense of smell).
• To study the functioning of the optic nerve, use the Golovin-Sivtsev table or Snellen table (determining visual acuity), visual fields (perimetroscopy), Rabkin table (color perception), examination of the fundus and optic nerve head, checking the pupillary reflex (also for the oculomotor nerve). Possible disorders are amaurosis, hemianopsia, impaired color vision, scotoma, congestive discs.
• To examine the function of the oculomotor nerve, first of all, pay attention to the position of the eyeball; if there is an external obliquity, this may indicate a violation of the innervation of this nerve. They also pay attention to the eyelid (or existing ptosis - drooping eyelid). They also check the reaction of the pupil to light, accommodation, and eye movements. Possible disturbances include external slanting, anisocoria (due to insensitivity to light), lack of accommodation, ptosis and double vision when looking in the direction opposite to the lesion.
• If the trochlear nerve is affected, a person cannot direct the eye downwards and laterally, and double vision also occurs.
• When examining the trigeminal nerve, they check superficial and deep sensitivity, reflexes, the link of which is the trigeminal nerve (supraglacial, mental, corneal, conjunctival), and chewing movements. Tactile sensitivity is checked with a cotton swab in the zones of innervation of the nerve branches and in the Zelder zones, pain sensitivity - thanks to a sharp object and in the same zones. The patient is asked to clench his teeth and move his lower jaw. Possible disturbances include anesthesia, hypoesthesia, hyperesthesia, pain, lack of chewing movements, trismus.
• The abducens nerve allows outward movement of the eye. This is the function that is tested when testing a nerve. Possible violations - double vision, internal slant.
• The facial nerve contains sensory, motor, and parasympathetic fibers. Check the general sensitivity of the auricle (similar to the trigeminal nerve); taste sensitivity is checked by applying a certain taste stimulus to the tongue (sweet, bitter, sour, salty); the patient is asked to smile, close his eyes; the function of the facial muscles is checked; hearing is checked (the function of the stapedius muscle, which is innervated by the nerve), Schirmer test to check the innervation of the lacrimal gland, checking salivation. Possible disorders - ageusia, facial paresis or paralysis, hyperacusis, lacrimation and salivation disorders.
• Hearing and balance depend on the vestibulocytic nerve. To test hearing, the doctor can whisper a word or sentence, and the patient has to repeat it; carry out the Rinne test, Weber test; the doctor observes the patient’s walking and stability in the Romberg position. Possible disorders are hypo- or hyperacusis, ataxia (with nystagmus), complete deafness.
• The ninth and tenth nerves are tested simultaneously. They check the condition of the soft palate, ask the patient to swallow, speak, listen to the patient’s voice (or it is not hoarse), and check the pharyngeal reflex. Possible disorders: overhang of the palate (half or full overhang), difficulty swallowing, hoarseness of voice. Also, with pathology of the vagus nerve, autonomic disorders can occur.
• Testing the accessory nerve involves asking the patient to turn his head to the side and raise his shoulders, that is, to check the innervation of the muscles. In the event of a disruption, movement will be limited or non-existent.
• To check the function of the hypoglossal nerve, the patient is asked to stick out his tongue (normally it extends along the midline), look at the condition of the tongue (absence or presence of atrophy, fasciculations).

Diseases

Peripheral neuropathies and neuralgia

Neuropathy is understood as any (inflammatory (neuritis) and non-inflammatory) process in the nerve trunk, which leads to deterioration or loss of innervation by this nerve and pain. In this case, the causes of inflammation can be a variety of factors: bacteria, viruses (usually herpeviruses), traumatic injuries, physical factors (for example, hypothermia or nerve compression), radiation, tumors. As already mentioned, neuritis leads to loss of innervation of the nerve: with neuritis of the facial nerve, facial expressions disappear, the functions of the salivary and lacrimal glands increase. With neuritis of the vestibulocochlear nerve, hearing loss occurs, coordination and balance deteriorate.

Non-inflammatory causes of neuropathy can be demyelinating diseases (such as multiple sclerosis), metabolic diseases (diabetes mellitus).

Neuralgia is a condition in which severe pain occurs in the area of ​​innervation of the sensory nerve. A common disease of this type is trigeminal neuralgia. It will cause a burning, sharp pain in the area of ​​innervation of the trigeminal nerve. Glossopharyngeal neuralgia manifests itself as pain in the pharynx, tonsils, tongue, that is, in the zone of innervation of the nerve of the same name. Sometimes only individual branches of nerves are involved in the process.

Strokes (neuropathies in the central nervous system)

Since, in addition to the trunk, the nerve system includes pathways to the central nervous system, nuclei and cortical centers, their damage also manifests itself as loss of innervation. If a hemorrhagic or ischemic stroke occurs in the area of ​​the trunk and affects the nuclei, then the nerve can be involved in alternating syndrome - loss of function of a certain cranial nerve on the affected side and paralysis or paresis, loss of sensitivity on the opposite side of the body. If a stroke occurs in the area of ​​the internal capsule or corona radiata, then all sensitivity and motor skills on the opposite side of the lesion, including the one provided by the cranial nerves, are lost. When the cortical analyzer is damaged, if the damage is located in the area that receives information from a certain cranial nerve, the function of this nerve is lost.

History of discovery and name

Opening

Ancient times and the Middle Ages

The first documentary descriptions of cranial nerves are found in the works of Claudius Galen, however, there is evidence that Herophilus already distinguished some cranial nerves (it is known for sure that he described the optic nerve, but did not give a name and believed that it was not a nerve, but a canal (poroi)). Also in his works, Galen referred to Marinos of Alexandria, who was the teacher of his teachers. Galen described (but did not give modern name) seven pairs of cranial nerves; he recognized as cranial nerves not only the cranial nerves themselves, but also the roots of the trigeminal nerve. So the Galenic classification is as follows (Roman numerals indicate the number of a pair of cranial nerves in its classification)

• I - optic nerve;
• II - oculomotor nerve;
• III - sensory root of the trigeminal nerve
• IV - motor root of the trigeminal nerve
• V - facial nerve + vestibulo-cochlear nerve;
• VI - glossopharyngeal nerve + vagus nerve + accessory nerve;
• VII - hypoglossal nerve

He did not consider the olfactory nerve a nerve, but only a process of the brain.

He also classified the sensory and motor nerves: the former were “soft”, the latter – “hard”.

This classification system persisted for a very long time, until the beginning of the Renaissance. Several factors contributed to this: dissections of human bodies were prohibited both in the Roman Empire and during the Middle Ages, Galen had very great authority in the world of medicine at that time, the Church followed science, and with the creation of the Inquisition increased its influence.

After the collapse of the Roman Empire, the center of scientific research shifted to the Middle East. However, Galen's works were also used here, so the classification of cranial nerves remained unchanged.

New time

Change came with the advent of the Renaissance, when access to bodies increased and the validity of old ideas could be tested.

The first classification, different from the Galenic ones, was created by Alessandro Benedetti in his Historia corporis humani 1502. So Galen’s VII nerve became II in his classification, the olfactory bulb and olfactory tract became the III pair of cranial nerves, the oculomotor and optic nerves formed the I pair of cranial nerves.

Andreas Vesalius in his De humani corporis fabrica(1543) also slightly changed the classification of nerves: two roots of the trigeminal nerve formed the III pair of cranial nerves, the IV pair became the palatine branch of the maxillary nerve. Other nerves were in the same positions as in Galena. Vesalius was also the first to describe the abducens and trochlear nerves, but considered them part of the oculomotor nerve.

Contributions to the understanding of the structure and branching of nerves were made by Fallopius, who described all three modern branches of the trigeminal nerve, the facial canal of the temporal bone and the string tympani.

The first classification to go beyond the seven nerves was that of Willis in his work Cerebri anatome(1,664). He identified the following nerves:

• I pair - olfactory tract and bulb
• II pair - optic nerve
• III pair - trochlear nerve
• IV pair - trigeminal nerve
• V pair - abducens nerve
• VII pair of facial nerve + auditory nerve
• VIII pair - glossopharyngeal nerve + vagus nerve + accessory nerve
• IX pair - hypoglossal nerve

Willis's work was very popular in Europe. Using it, the Dutch surgeon Godefroy described 11 cranial nerves: he separately described the glossopharyngeal, vagus and accessory nerves. However, this classification did not gain much popularity, and Sommering's classification was used by Willis.

The latest classification (modern) belongs to Samuel Thomas Semmering, who in 1778 described all 12 cranial nerves and arranged them according to modern classification. It was this classification that was adopted as the standard when the BNA was approved in 1895. It remained unchanged during the adoption of the PNA (1955) and during the approval of the latter anatomical terminology in Rio de Janeiro in 1997.

However, in 1878, Fritish described the neurostrangial nerve found in fish, which was later called the terminal nerve. In 1905, Vries' experiments on human embryos, and in 1914 (according to other sources in 1913) - experiments by Brookover and Johnston on adults - confirmed the presence of this nerve in humans. Since all the nerves already had their number from I to XII, he received the non-Roman symbol “0”. It is also denoted by the Roman letter "N".

Also in different times The term “cranial nerves” was different. Galen believed that cranial nerves are ending in the brain. Vesalius used the term “nervi a cerebro originem ducentes”, that is nerves that begin in the brain, or nerves of the brain. Willis called them those that are “born” in the skull. In 1895, the first unified anatomical terminology (Basel - BNA) for nerves they decided to use the term nerve cerebrales- brain nerves. In 1935, a revision of the nomenclature took place in Jena; this time the term was adopted nervi capitales- main nerves. It was only in 1955, in Paris, that the term began to be used nervi craniales- cranial nerves - and when viewing P.N.A. in 1980 alternative term nervi encephalici. However, at the last review and approval Terminology Anatomica a single term was adopted - nervi craniales.

History of nerve names

Nerve	Etymology of the name	First named	The scientist who gave the name	Reason for the name
Terminal nerve (lat. Nervus terminalis)	from lat. terminalis- extreme	1 905	Albert William Losey	The nerve was first called the accessory olfactory nerve, but due to its unexplored function, its name was changed to terminal, due to its proximity to the terminal plate of the brain
Olfactory nerve (lat. Nervus olfactorius)	classical lat. olfacere- sniff, post-classical olfactorius(two suffixes -tor- (suffix to form a noun from a specific verb) and -i-(indicates belonging to a function))	1651	Thomas Bartolin	The nerve got its name due to its connection with the function of smell
Optic nerve (lat. Nervus opticus)	from ancient Greek ὀπτικός (optikos)	not known for sure; Galen provides information that some of his contemporaries called the nerve the optic nerve	?	The nerve is so named because it is involved in the function of vision.
Oculomotor nerve (lat. Nervus oculomotorius)	postclassical Latin word, combined from two Latin words: oculus- eye and motore- moving; two suffixes are also added: -tor And -i-	1783	Johann Pfeffinger	So named because of its function (innervates the muscles of the eyeball and thus moves it)
Trochlear nerve (lat. Nervus trochlearis)	from lat. trochlea- block	1670	William Molins	The nerve is named because it innervates the superior oblique muscle, the tendon of which makes a bend that resembles a pulley
Trigeminal nerve (lat. Nervus trigeminus)	from lat. trigeminus- triple	One thousand seven hundred thirty two	Jacob Winslov	It got its name because of its shape: the main trunk, which emerges from the cerebellopontine angle, is divided into three massive branches
Abducens nerve (lat. Nervus abducens)	from lat. abducere- to divert, with the addition of a suffix -ens, characteristic of imperfect participles	1778	Samuel Thomas Semmering	The nerve received its name because of the function it provides, namely, the retraction of the eye outward
Facial nerve (lat. Nervus facialis)	from lat. faciei- face; postclassical facialis- something that relates to the face	1778	Samuel Thomas Semmering	The nerve received its name through the innervation of the facial muscles, its “belonging” to the face
Intermediate nerve (lat. Nervus intermedius) part of the facial nerve	from lat. intermedius- intermediate	1778	Heinrich August Wriesberg	Due to the close proximity of the facial and vestibulocochlear nerves, they were long considered one nerve; in this case, the intermediate nerve was considered as a connecting branch between them, that is, an intermediate
vestibulocochlear nerve (lat. Nervus vestibulocochlearis)	from lat. vestibulum- vestibule; from lat. cochlea- curl, twist and suffix -ari-	1961	Collegium when viewing PNA	The name comes from the two anatomical structures with which the nerve communicates in the inner ear
Glossopharyngeal nerve (lat. Nervus glossopharyngeus)	from ancient Greek γλῶσσα (glossa)- language and from other Greek φάρυγξ (pharynx)- pharynx, throat	1753	Albrecht von Haller	The name comes from the fact that the anatomist who examined the nerve described that it is woven into the pharynx and the root of the tongue
Vagus nerve (lat. Nervus vagus)	from lat. vagus- prodigal, wandering, traveling	1651	Thomas Bartolin	The nerve got its name due to its length and extensive branching in the human body
Accessory nerve (lat. Nervus accessorius)	from the Latin word POSTCLASSICAL accesorius- additional	One thousand six hundred sixty six	Thomas Willis	Due to the close location to the wandering one and the branches to it, it was considered as an “attachment” to the modern X pair
Hypoglossal nerve (lat. Nervus hypoglossus)	from ancient Greek γλῶσσα (glossa)- language and with the addition of a prefix hypo-- under-	One thousand seven hundred thirty two	Jacob Winslov	Characterizing the relationship to tongue function and anatomical placement

Video on the topic

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 is it?

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. It consists of 2 components, different in their 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 and is 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 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 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, 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

This couple has enough defeats rare case. 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, the masticatory muscles can be paralyzed.

Abducens nerve

The main symptom is convergent strabismus. Most often, patients complain that they have double vision, and those 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 in comparison with 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's hit rear end the tongue ceases to distinguish tastes, the top of the pharynx loses its receptivity, 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.

Vagus nerve

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.

CRANIAL NERVES [nervi craniales (PNA), nervi capitales (JNA), nervi cerebrales (BNA); synonym; head nerves, cranial nerves] - nerves extending from the brain in 12 pairs; innervate the skin, muscles, organs of the head and neck, as well as a number of organs of the thoracic and abdominal cavities.

The first mentions of cranial nerves are found in the works of Erasistratus (4-3 centuries BC) and Herophilus (He-philos, 3 century BC). According to the ideas of Erasistratus, a “spiritual pneuma” is formed in the brain, which flows out of it along the nerves. K. Galen adhered to the same idea about the functions of nerves, including cranial nerves. Cranial nerves were described in 1543 by A. Vesalius, the details of their structure were subsequently specified by K. Varoliy, Viessens (R. Vieussens, 4641 - 1715), H. Wrisberg (1739-1808), I. Prohaska, Arnold ( F. Arnold, 1803-1890). Recently, the main attention has been paid to the study of the intra-trunk structure of cranial nerves, the composition of nerve conductors, and the development of cranial nerves.

The specificity of the formation and structure of cranial nerves in phylogenesis and ontogenesis is determined by the peculiarities of the development of the head, which in turn is associated with the formation of sensory organs and gill arches (with their muscles), as well as the reduction of myotomes in the head region. During the process of phylogenesis, the cranial nerves lost their original segmental arrangement and became highly specialized. Thus, the first pair (olfactory nerve) and the second pair (optic nerve), formed by the processes of intercalary neurons, represent nerve pathways, connecting the organ of smell and organ of vision with the brain. III pair (oculomotor nerve), IV pair (trochlear nerve) and VI pair (abducens nerve), which developed in connection with the cephalic pre-auricular myotomes, innervate the muscles of the eyeball formed in these myotomes. These nerves are similar in origin and function to the anterior roots of the spinal nerves. V, VII, IX and X pairs, by origin and nature of branching, are visceral branchial nerves, since they innervate the skin, muscles of the corresponding visceral gill arches, and also contain visceral motor fibers innervating the glands and organs of the head and neck. A special place is occupied by the V pair (trigeminal nerve), which is formed by the fusion of two nerves - the deep ophthalmic nerve, innervating the skin of the front of the head, and the trigeminal nerve itself, innervating the skin and muscles of the mandibular arch. The deep optic nerve as an independent nerve is found only in lobe-finned fish. The VII pair (facial nerve) innervates the lateral line organs and muscles derived from the hyoid arch in fish; in terrestrial vertebrates - superficial muscles of the neck; in primates - facial muscles. During development, the VIII pair (vestibular-cochlear nerve) separates from the facial nerve, providing specific innervation to the organ of hearing and balance. Pair IX (glossopharyngeal nerve) and pair X (vagus nerve) are typical branchial nerves. In cyclostomes, fish and amphibians, only the ten pairs of cranial nerves listed above are constantly present. Pair XI - accessory nerve, consisting of visceral motor nerve fibers, develops only in higher vertebrates by separating the caudal part of the vagus nerve. The XII pair (hypoglossal nerve) appears for the first time in amniotes as a result of the fusion of roots that are released from the spinal nerves.

In ontogenesis in the human embryo, the formation of cranial nerves occurs at the stage of formation of the head somites. The cranial nerves include somatic and visceral sensory, as well as somatic and visceral motor conductors. Pairs I and II develop as outgrowths from the walls of the terminal and diencephalon vesicles (see Brain). The development of the remaining ten pairs of cranial nerves occurs similarly to the development of the anterior (motor) and posterior (sensory) roots of the spinal nerves (see Spinal Cord). The motor components of the cranial nerves are formed by the germination of bundles of nerve fibers into the anlage of the head muscles from the cellular accumulations formed in the stem part of the developing brain - the anlage of the motor nuclei (see Nuclei of the central nervous system). The sensory components of the cranial nerves are formed as a result of the germination of bundles of nerve fibers, which are processes of neuroblasts located in the germinal ganglia of the corresponding nerves.

Features of the subsequent formation of cranial nerves in humans are associated primarily with the timing of development and the degree of myelination of nerve fibers. The fibers of the motor nerves myelinate before the mixed and sensory nerves. The only exception is the fibers of the vestibular (vestibular) part of the VIII pair, which by the time of birth are almost completely myelinated. Myelination of cranial nerves precedes myelination of spinal nerves. Between the ages of 1 and 17 years, almost all nerve fibers of the cranial nerves are covered with myelin sheaths. The final formation of the gasserian ganglion of the trigeminal nerve occurs by the age of 7 years, the glossopharyngeal and vagus nerves - even later. In newborns, clusters of spinal ganglion cells are often found in the motor cranial nerves, which gradually disappear after 4 years of age, but individual cells sometimes persist in adults.

With age, as the head grows, the length and diameter of the trunks of the cranial nerves increase. Their thickening is partly due to an increase in the number connective tissue in the epineurium and endoneurium. IN old age the amount of connective tissue in the endoneurium decreases, and in the epineurium, on the contrary, it increases. In general, changes in cranial nerves associated with involution obey the laws of age-related restructuring of nerves (see).

In the cranial nerves, afferent fibers quantitatively significantly predominate over efferent ones. As part of the cranial nerves, on one side only, about 1.5 million afferent fibers enter the brain (of which the optic nerve accounts for approximately 1 million nerve fibers), and about 100 thousand efferent fibers leave it.

There is no uniform classification of cranial nerves. Depending on the predominant intra-trunk composition, motor nerves (III, IV, VI, XI and XII pairs) are distinguished, innervating the muscles of the eye, tongue, sternocleidomastoid and partially trapezius muscles; mixed nerves (V, VII, IX and X pairs), containing all functional components, with the exception of motor somatic nerve conductors; nerves of the sense organs - pairs I and II, which, due to the peculiarities of their origin and structure, are combined into a separate group. The VIII pair is also conventionally included in this group of sensory nerves on the grounds that the vestibulocochlear nerve provides specific innervation to the organ of hearing and balance (see Sense Organs).

All cranial nerves, with the exception of pairs I and II (see Optic nerve, Olfactory nerve), are connected to the brain stem, in which their motor, sensory and autonomic nuclei are located (see Autonomic nervous system). Thus, the nuclei of the III and IV pairs of cranial nerves are located in the midbrain (see), the nuclei of the V, VI, VII, VIII pairs are mainly in the tegmentum of the pons (see. The cerebral bridge), the nuclei IX, X, XI, XII pairs - in the medulla oblongata (see). The places where cranial nerves exit or enter the brain are associated with these same parts of the brain (Fig. 1). Each cranial nerve has a specific exit point from the cranial cavity.

Anatomy, physiology and methods of studying individual cranial nerves are set out in the articles Olfactory nerve (see), Optic nerve (see), Oculomotor nerve (see), Trochlear nerve (see). Trigeminal nerve (see), Abducens nerve (see), Facial nerve (see), Anterior cochlear nerve (see), Glossopharyngeal nerve (see), Vagus nerve (see), Accessory nerve (see. ), Hypoglossal nerve (see).

Pathology

Impaired function of each cranial nerve with different levels its lesions are manifested by clear symptoms, the analysis of which plays an important role in making a clinical and topical diagnosis of diseases of the nervous system. There are syndromes of isolated damage to individual cranial nerves, syndromes of complex damage to supranuclear conductors, nuclei and fibers of cranial nerves in the brain stem with simultaneous involvement in the pathological process of conductors of the motor, sensory, extrapyramidal and autonomic systems (the so-called cross, or alternating, syndromes ) and, finally, syndromes of combined lesions of several. Cranial nerve with extracerebral localization of the process in the cranial cavity (sometimes outside the skull). Clinical picture isolated lesions of cranial nerves are described in articles devoted to individual cranial nerves.

Cross, or alternating syndromes (see), have important topical and diagnostic significance. Alternating syndromes with damage to the oculomotor and trochlear nerves indicate the localization of the lesion in the region of the midbrain (see), with damage to the trigeminal, abducens, facial and vestibulocochlear nerves - the presence of a lesion in the pons (see Pontine cerebri), with damage to the glossopharyngeal, vagus, accessory and hypoglossal nerves - in the medulla oblongata (see). This topical division is somewhat arbitrary, since the nuclei of the facial and vestibulocochlear nerves are located on the border of the pons and the medulla oblongata, the sensory nuclei of the trigeminal nerve are located throughout the entire length of the brain stem, and the nucleus of the accessory nerve is actually already in the first cervical segments of the spinal cord.

Symptom complexes caused by damage to the extracerebral parts of several cranial nerves, in certain combinations and the sequence of occurrence of disorders, develop in various pathological processes of intracranial and sometimes extracranial localization. Below are the most common ones in clinical practice syndromes caused by combined lesions of the cranial nerves. Based on the identification of syndromes of combined lesions of extracerebral parts of the cranial nerves, it is possible to make not only a topical diagnosis, but to a certain extent also a clinical diagnosis of a tumor, aneurysm, or inflammatory process in this area.

The syndrome of unilateral damage to all cranial nerves in the area of ​​the base of the skull (synonym: half-base of the skull syndrome, intracranial hemipolyneuropathy syndrome, hemiplegia of cranial nerves, Garcin's syndrome) was described in 1926 by R. Garcin. Characterized by damage to the roots of the cranial nerves on one half of the base of the skull, the degree and sequence of development of the syndrome depend on the initial localization pathological process, its nature and distribution features. In this case, all functions of the cranial nerves (motor, sensory, autonomic) are affected in a peripheral manner. Conductive disturbances of movement and sensitivity, as well as congestion in the fundus of the eye are absent in this syndrome. An increase in intracranial pressure and pathological changes in the cerebrospinal fluid are also, as a rule, not observed. The syndrome develops with sarcomas of the base of the skull, metastases of various tumors in the meninges on the lower surface of the brain, with neuroleukemia (see Leukemia), extracranial tumors growing from the nasopharynx, paranasal (paranasal, T.) sinuses, parotid gland and spreading to the base of the skull through its various openings (round, oval, torn, jugular, etc.).

Anterior cranial fossa syndrome (synonym: basal frontal syndrome, Foster-Kennedy syndrome) was described in 1911 by Kennedy (F. Kennedy; see Kennedy syndrome). It is characterized by combined damage to the olfactory and optic nerves. It manifests itself as primary atrophy of the optic nerve with decreased vision (sometimes to the point of blindness) on one side, a congestive nipple (disc, T.) of the optic nerve on the other, impaired sense of smell, first on the affected side, then (sometimes) on the other side; Occasionally, mental disorders characteristic of damage to the frontal lobe of the brain (foolishness, untidiness, etc.) appear. The syndrome develops with intracranial tumors, hematomas, traumatic brain injuries with basal-frontal brain contusion, meningiomas of the olfactory triangle, abscesses of the frontal lobe, as well as with supranasal tumors that destroy the bones of the anterior cranial fossa and compress the structures located in it. A sign of a tumor or other space-occupying process in the cranial cavity is a predominantly unilateral lesion (especially in the initial stage), usually not characteristic of inflammatory processes - basal meningitis (for example, syphilitic), encephalitis, etc.

Olfactogenital syndrome (synonymous with Kallmann syndrome) was described by F. Kallmann in 1944. Characterized by a lack of sense of smell due to damage olfactory nerves and a complex of endocrine disorders that cause delayed sexual development (secondary or hypogonadotropic hypogonadism with eunuchoidism in men). The mechanism of damage to the first pair of cranial nerves, combined with a violation of the gonadotropic function of the pituitary gland (see), is not completely clear. Currently, the hereditary nature of this syndrome is assumed (cases of consanguinity between parents of patients have been described).

Superior orbital fissure syndrome (synonym: fissurae orbitalis superioris syndromum, sphenoidal fissure syndrome) was described by E. Pichon in 1924 and M. Casteran in 1926. It is characterized by a combined unilateral lesion of the oculomotor, trochlear, abducens nerves and the first branch of the trigeminal nerve, emerging through the superior orbital fissure from the cranial cavity into the orbital cavity (see Orbit, Ophthalmoplegia). It manifests itself as complete (less often partial) paralysis of the muscles of the eyeball (ptosis of the upper eyelid, complete ophthalmoplegia, pupil dilation and lack of reaction to light), pain and decreased sensitivity (or anesthesia) in the area of ​​innervation of the first branch of the trigeminal nerve (cornea, upper eyelid, half forehead). Most often, the syndrome develops with tumors and hyperostosis in the area of ​​the superior orbital fissure, with syphilitic periostitis of the wings of the sphenoid bone, etc. (Fig. 2).

Orbital apex syndrome (synonymous with Rolle's syndrome) was described by Rollet in 1927. It is characterized by a combination clinical manifestations superior orbital fissure syndrome with symptoms of damage to the optic nerve emerging from the orbit and passing through the optic canal (canalis opticus) into the cranial cavity. Along with symptoms of damage to the III, IV, VI cranial nerves and the I branch of the trigeminal nerve (see above), blindness develops on the same side due to optic nerve atrophy. The syndrome occurs when pathological processes spread from the area of ​​the superior orbital fissure to the apex of the orbit, causing compression of the optic nerve or disruption of the venous outflow from the orbital veins; in the latter case, secondary glaucoma usually develops (see). Most often, the lesion is caused by a retrobulbar tumor, osteomyelitis of the orbital bones, and tumors growing from the cavernous (cavernous, T.) sinus into the orbit.

Unilateral ophthalmic neuralgic syndrome (synonymous with Godtfredsen's syndrome) was described by E. Godtfredsen in 1944. Its distinctive feature is the combined damage to the cranial nerves. It begins with damage to the second branch of the trigeminal nerve; subsequently, the abducens nerve, oculomotor nerve, trochlear nerve, I branch of the trigeminal nerve, and optic nerve are involved in the process. The sympathetic perivascular plexus of the internal carotid artery (internal carotid plexus) is also involved in the process, which causes disturbances in the sympathetic innervation of the eye on the affected side. Clinically, the syndrome is manifested by neuralgia of the maxillary nerve (see Trigeminal nerve), symptoms of damage to the nerves innervating the muscles of the eyeball (starting with the abducens muscle), a progressive decrease in vision in one eye, the development of Bernard-Horner syndrome (narrowing of the palpebral fissure, miosis, enophthalmos) on the affected side (see Bernard-Horner syndrome). The syndrome is caused by the growth of extracranial malignant tumors (usually tumors of the nasopharynx) through the foramen rotundum into the cranial cavity and then into the orbit.

The syndrome of the lateral wall of the cavernous sinus (synonymous with the syndrome of the outer wall of the cavernous sinus) was described by S. Foix in 1920. It is characterized by a combined lesion of the cranial nerves innervating the muscles of the eyeball (III, IV, VI), and the I branch of the trigeminal nerve, passing in the lateral wall of the cavernous sinus to the superior orbital fissure and the orbit. It differs from the superior orbital fissure syndrome (see above) by the initial damage to the abducens nerve (convergent strabismus, diplopia) and the first branch of the trigeminal nerve (sharp pain in the orbital area, half of the forehead) with the subsequent addition of damage to the oculomotor, trochlear nerves and the development of complete ophthalmoplegia (see .). Usually the syndrome is caused by a pathological process in the middle cranial fossa (tumors of the temporal lobe, pituitary gland, craniopharyngiomas, sarcomas of the skull base, purulent process in the main, or sphenoid, sinus, etc.). acting externally on the cavernous sinus with the anatomical structures contained in it.

Foramen lacerum syndrome (synonym: foraminis lacerum syndromum, Jefferson syndrome) was described by G. Jefferson in 1937 as a neurological lesion that develops with an aneurysm of the internal carotid artery in the area of ​​the foramen laceration at the base of the skull. The severity of combined damage to the optic, oculomotor, trochlear and trigeminal nerves in this syndrome depends on the size of the aneurysm. Clinically, the syndrome is manifested by headache in the frontal and orbital areas, a sensation of pulsating noise in the head on the affected side, transient or persistent ptosis of the upper eyelid (see Ptosis) and diplopia (see), sometimes pulsating exophthalmos (see), pupil dilation, edema optic disc, hypoesthesia of the cornea, half of the forehead, cheeks.

Cavernous sinus syndrome (synonym: cavernous sinus syndrome, cavernous sinus syndrome, Bonnet syndrome) was described by P. Bonnet in 1955. Combines the clinical symptoms of four separately described syndromes - superior orbital fissure syndrome, orbital apex syndrome, lateral wall of the cavernous sinus syndrome and foramen lacerum syndrome. It manifests itself as complete ophthalmoplegia, pain and decreased sensitivity in the area of ​​innervation of the first branch of the trigeminal nerve, unilateral exophthalmos with swelling of the eyelids, hyperemia and swelling of the conjunctiva of the eye (chemosis). It is usually caused by space-occupying formations (meningioma, gumma, aneurysm, etc.), which are located in the cavernous sinus, compress the cranial nerves and disrupt venous circulation in the orbital and facial veins. With the development of the syndrome due to sinus thrombosis (see Thrombosis of cerebral vessels), symptoms of a septic condition may be observed (see Sepsis); with an aneurysm of the internal carotid artery in the cavernous sinus or in the case of arteriosinus anastomosis, a pulsating noise in the head on the affected side is often noted; exophthalmos may also be pulsating. With prolonged congestion in the fundus (see) and the spread of the process from the cavernous sinus along the optic nerve canal, damage to the optic nerve develops, leading to blindness, as well as secondary glaucoma. With a limited inflammatory process in the cavernous sinus, the pathological symptom complex usually quickly regresses under the influence of anti-inflammatory treatment and therapy with glucocorticoid hormones. In this case, cavernous sinus syndrome is referred to as Toulouse-Hunt syndrome.

Petrosphenoidal space syndrome (synonym: petrosphenoidal syndrome, Jaco's syndrome) was described by Jaco (M. Jacod) in 1921. A characteristic feature of the syndrome is hearing loss due to impaired patency of the Eustachian (auditory, T.) tube, the development of combined unilateral damage to the oculomotor, trochlear, abducens nerves, I and II branches (sometimes III branches) of the trigeminal nerve, and the optic nerve. The syndrome consists of unilateral deafness, ptosis, convergent strabismus (see), dilation of the pupil on the affected side, paresthesia, pain, and then decreased sensitivity on the face (in the innervation zones of the I and II branches of the trigeminal nerve), paralysis of the masticatory muscles (see. ), decreased vision. The syndrome is most often caused by growth malignant tumor from the nasopharynx or laryngopharynx, sarcoma eustachian tube, spreading through the lacerated foramen into the cranial cavity, into the cavernous sinus. With limited spread of the process in the cranial cavity, damage to the optic nerve may not occur and paralysis of the masticatory muscles may not develop.

Paratrigeminal syndrome (synonym: paratrigeminal sympathetic nerve palsy, Raeder's syndrome) was described by G. J. Raeder in 1918. It is characterized by a combined lesion of the sympathetic perivascular plexus of the internal carotid artery and the Gasserian (trigeminal, T.) node or the I and II branches of the trigeminal nerve located in close proximity to it (see). It manifests itself as a unilateral paroxysmal pulsating headache, pain and paresthesia of half the forehead, eyes, cheeks on the affected side, incomplete (sometimes complete) Bernard-Horner syndrome also on the affected side. Caused by limited pathological processes of various nature (tumors, inflammatory processes, injuries) at the base of the skull, near the gasserian node; can develop with aneurysms of the internal carotid artery of the same location.

The syndrome of the apex of the pyramid of the temporal bone (synonym: petrosum-syndromum, Gradenigo syndrome) was described by J. Gradenigo (see vol. 15, additional materials) in 1904. It is characterized by combined lesions of the abducens and trigeminal nerves on one side, and rarely also lesions of the oculomotor, trochlear and facial nerves. Develops with otogenic or viral infections(see Petrositis), fractures of the base of the skull (for more details, see Gradenigo syndrome).

Internal auditory canal syndrome (synonymous with Lyanitz syndrome) occurs with a combined unilateral lesion of the facial and vestibulocochlear nerves at the level of the internal auditory canal. Manifested by symptoms of peripheral damage to the facial nerve at this level (see Facial nerve), decreased hearing and noise in the ear on the affected side, in more late stages- changes in vestibular excitability (instability, dizziness). Most often caused by neuroma of the cochlear root of the vestibulocochlear nerve (see).

Syndrome of the geniculate ganglion (synonym: geniculatum-syndromum, neuralgia of the geniculate ganglion, Hunt's neuralgia) is a lesion of the geniculate ganglion (knot of the knee, T.) and the trunk of the facial nerve (see) in the fallopian (facial) canal. The syndrome is caused by a neuroviral infection, usually combined with damage to the vestibulocochlear nerve at this level, sometimes to the trigeminal nerve, as well as to the cervical nodes of the sympathetic trunk on the affected side. The clinical picture depends on the degree of involvement of the listed anatomical formations in the process (see Hunt syndrome). Sometimes the symptom complex is dominated by vestibular disorders with severe dizziness, nystagmus - Frankl-Hochwarth syndrome.

Jugular foramen syndrome (synonym: foraminis juqularis syndromum, Vernet's syndrome) was described by M. Vernet in 1916. Includes symptoms of unilateral combined damage to the glossopharyngeal, vagus and accessory nerves emerging from the cranial cavity through the jugular foramen (Fig. 3). In this case, peripheral paralysis of the muscles of the soft palate, larynx, pharynx, sternocleidomastoid and trapezius muscles on the side of the pathological focus occurs; impaired taste sensitivity in the root of the tongue, decreased sensitivity of the soft palate, mucous membrane of the posterior pharyngeal wall, pharynx, anterior surface of the epiglottis, eustachian tube, and tympanic cavity on the affected side. In addition, on the affected side there is a sagging of the soft palate, a displacement of the posterior wall of the pharynx to the healthy side, and drooping of the shoulder girdle (girdle of the upper limbs, T.). The patient's head is turned in the direction opposite to the lesion, the chin is raised. The voice is usually hoarse, with a nasal tint; swallowing solid food is difficult; the soft palate reflex and the pharyngeal reflex are absent on the affected side; Tachycardia, urge to cough, and suffocation are sometimes observed. The syndrome is caused by pathological processes at the base of the skull, in the area of ​​the jugular foramen, more often the growth of tumors (mainly sarcomas of the skull base), thrombosis of the sinuses of the dura mater (see Thrombosis of cerebral vessels) with the spread of the process to the area of ​​the superior bulb of the internal jugular vein, phlebitis of large veins of the neck, phlegmon of the submandibular (submandibular, T.) salivary glands, fractures of the base of the skull. In the latter case, when the fracture line passes not only through the jugular foramen, but also through the canal of the hypoglossal nerve (see), Vernet-Sicard-Collet syndrome develops - a combination of signs of damage to the cranial nerves in the area of ​​the jugular foramen with unilateral peripheral paralysis and atrophy muscles of the tongue (the tongue is tilted towards the affected side).

Retroparotid region syndrome (synonym: posterior pharyngeal region syndrome, Villaret syndrome) was described by Villaret (M. Villaret) in 1916. Includes symptoms of unilateral combined lesions of the glossopharyngeal, vagus, accessory, hypoglossal nerves and cervical ganglia of the sympathetic trunk. It manifests itself clinically as Vernet-Sicard-Collet syndrome (see above) and Bernard-Horner syndrome (see Bernard-Horner syndrome) on the affected side. Sometimes paresis of the facial muscles occurs due to damage to the extracranial branches of the facial nerve. The syndrome is caused by various pathological processes localized behind the parotid gland (abscesses, tumors, inflammatory infiltrates, injuries, etc.), involving the cranial nerves listed above.

Cerebellopontine angle syndrome was described by H. Cushing in 1917. Includes unilateral damage to the roots of the facial, vestibulocochlear nerve and the intermediate nerve passing between them. Depending on the size of the pathological focus and the direction of spread of the process (see. Cerebellopontine angle), lesions of the trigeminal and abducens nerves and disorders of cerebellar functions on the side of the lesion (see. Cerebellum), pyramidal symptoms on the side opposite to the lesion (see. Pyramid system). Main wedge, manifestations: hearing loss and noise in the ear, dizziness, peripheral paralysis of facial muscles (facial muscles, T.), hypoesthesia, pain and paresthesia in half of the face, unilateral decrease in taste sensitivity on the anterior 2/3 of the tongue, paresis of the rectus lateral muscle eyes with convergent strabismus and diplopia. When the process affects the brain stem, hemiparesis occurs on the side opposite to the lesion, cerebellar ataxia (see) on the side of the lesion. The syndrome is most often caused by neuroma of the cochlear root of the vestibulocochlear nerve, cholesteatomas, hemangiomas, cystic arachnoiditis, leitomeningitis of the cerebellopontine angle. Limited damage to only the nerves of the cerebellopontine angle (VII and VIII nerves) is often caused by an aneurysm of the basilar artery.

Bulbar palsy syndrome (see Bulbar palsy) is a symptom complex that occurs with combined damage to the roots or trunks of the glossopharyngeal, vagus and hypoglossal nerves both inside and outside the cranial cavity. In this case, speech is impaired (dysarthria, aphonia, nasal tone of voice), swallowing (dysphagia), which is caused by peripheral paralysis of the muscles of the soft palate, pharynx, larynx, and tongue. There is atrophy of the muscles of one half of the tongue, there is no pharyngeal reflex and a reflex from the soft palate on the affected side. On the same side, sensitivity in the area of ​​innervation of the affected nerves is impaired. Tachycardia and shortness of breath are possible. The syndrome is most often caused by tumors and inflammatory processes in the posterior cranial fossa; bilateral lesions sometimes develop with diphtheritic polyneuritis, with Guillain-Barré polyneuropathy, etc. (see Polyneuritis).

The diagnosis of a particular lesion syndrome is made on the basis of a characteristic combination of signs of damage to closely located cranial nerves and adjacent intracranial structures (the principle of anatomical syntopy). The clinical diagnosis must be confirmed by the results of additional studies, primarily craniography (see). To do this, special targeted images are taken that reveal changes in bone structures in the area of ​​the pathological process - expansion or narrowing of the superior orbital fissure, optic nerve canal, expansion of the internal auditory canal, changes in the contours and sizes of the round lacerated or jugular foramen, etc. (see Skull) . In cases of cerebellopontine angle syndrome, foramen lacerum syndrome, as well as in cavernous sinus syndrome caused by an aneurysm of the internal carotid artery or carotid-cavernous anastomosis, angiography is of great diagnostic importance (see Vertebral angiography, Carotid angiography). Computed tomography data of the head (see Computed tomography), which makes it possible to identify tumors of the cavernous sinus, apex of the orbit, cranio-orbital tumors, foci of brain contusion, etc., are of undoubted diagnostic value. However, with extracerebral processes of basal localization, which are often not widespread, computed tomography is not as informative as with intracerebral processes.

Treatment and prognosis depend on the location of the pathological process, its severity and the nature of its course.

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E. I. Minakova; 5. I. Kandel (superior orbital fissure syndrome), V. I. Kozlov (an.).