There are 13 pairs of cranial nerves (Fig. 222): zero pair - terminal nerve n. terminalis); I- olfactory (n. olfactorius); II - visual (n. opticus); III - oculomotor (n. oculomotorius); IV- block, (n. trochlearis); V- trigeminal (n. trigeminus); VI- outlet (n. abducens); VII - facial (n. facialis); VIII - vestibulocochlearis (n. vestibulocochlearis); IX- glossopharyngeal (n. glossopharyngeus); X- wandering (n. vagus); XI- additional (n. accessorius); XII- sublingual (n. hypoglossus).
DEVELOPMENT AND STRUCTURAL PRINCIPLES OF CRANIAL NERVE
Olfactory and optic nerves - specific nerves of the sense organs, develop from the forebrain and are its outgrowths. The rest of the cranial nerves differentiated from the spinal nerves and therefore are fundamentally similar in structure to them. Differentiation and transformation of the primary spinal nerves into cranial nerves are associated with the development of the sense organs and gill arches with their muscles, as well as with the reduction of myotomes in the head region (Fig. 223). However, none of the cranial nerves corresponds completely to the spinal nerves, since it is not composed of anterior and posterior roots, but only of one anterior or posterior one. Cranial nerves III, IV, VI pairs correspond to the anterior roots. Their nuclei are located ventrally, they innervate the muscles developed from the 3 anterior somites of the head. The remaining anterior roots are reduced.
The other cranial nerves V, VII, VIII, X, XI and XII pairs can be considered as homologues of the posterior roots. These nerves are associated with muscles that originate in the course of evolution from the muscles of the gill apparatus and developed in embryogenesis from the lateral plates of the mesoderm. In lower vertebrates, the nerves form two branches: anterior motor and posterior sensory.
Rice. 222. cranial nerves:
a - places of exit from the brain; b - places of exit from the skull;
1 - olfactory tract; 2 - optic nerve; 3 - oculomotor nerve; 4 - block nerve; 5 - trigeminal nerve; 6 - abducens nerve; 7 - facial nerve; 8 - vestibulocochlear nerve; 9 - oculomotor nerve; 10 - vagus nerve; 11 - accessory nerve; 12 - hypoglossal nerve; 13 - spinal cord; 14 - medulla oblongata; 15 - bridge; 16 - midbrain; 17 - diencephalon; 18 - olfactory bulb
In higher vertebrates, the posterior branch of the cranial nerves is usually reduced.
The X and XII cranial nerves have a complex origin, as they are formed during evolution by the fusion of several spinal nerves. In connection with the assimilation of the trunk metameres by the occipital region of the head, part of the spinal nerves moves cranially and enters the region of the medulla oblongata. Subsequently, the IX and XI cranial nerves are separated from a common source - the primary vagus nerve; they are, as it were, its branches (Table 14).
Rice. 222. Ending
Table 14 The ratio of somites of the head, branchial arches and cranial nerves with
their roots
Rice. 223.Cranial nerves of the human embryo. The gill arches are indicated by Arabic numerals, the nerves by Roman numerals:
1 - pre-ear somites; 2 - behind the ear somites; 3 - accessory nerve associated with the mesenchyme of the 5th gill arch; 4 - parasympathetic and visceral sensory fibers of the vagus nerve to the anterior and middle primary intestine; 5 - cardiac ledge; 6 - tympanic nerve (visceral sensory fibers to the middle ear and parasympathetic fibers to the parotid salivary gland); 7 - taste fibers to the anterior 2/3 of the tongue and parasympathetic fibers to the salivary glands; 8 - olfactory placode; 9 - mesenchyme of the head; 10 - submandibular node; 11 - eye glass; 12 - the rudiment of the lens; 13 - pterygopalatine node; 14 - ciliary knot; 15 - ear knot; 16 - ophthalmic nerve (sensitive to the orbit, nose and front of the head)
Rice. 224. Functional features of the cranial nerves: I - olfactory nerve; II - optic nerve; III - oculomotor: motor (external muscles of the eye, ciliary muscle and muscle that narrows the pupil); IV - trochlear nerve: motor (superior oblique muscle of the eye); V - trigeminal nerve: sensitive (face, paranasal sinuses, teeth); motor (chewing muscles); VI - abducens nerve: motor (lateral rectus muscle of the eye); VII - facial nerve: motor (facial muscles); intermediate nerve: sensitive (taste sensitivity); efferent (parasympathetic) (submandibular and sublingual salivary glands); VIII - vestibulocochlear nerve: sensitive (cochlea and vestibule); IX - glossopharyngeal nerve: sensitive (posterior third of the tongue, tonsil, pharynx, middle ear); motor (stylo-pharyngeal muscle); efferent (parasympathetic) (parotid salivary gland); X - vagus nerve: sensitive (heart, larynx, trachea, bronchi, lungs, pharynx, gastrointestinal tract, outer ear); motor (parasympathetic) (same area); XI - accessory nerve: motor (sternocleidomastoid and trapezius muscles); XII - hypoglossal nerve: motor (muscles of the tongue)
According to their functional affiliation, the cranial nerves are distributed as follows (Fig. 224). I, II and VIII pairs belong to the sensory nerves; III, IV, VI, XI and XII pairs are motor and contain fibers for striated muscles; V, VII, IX and X pairs are mixed nerves, as they contain both motor and sensory fibers. At the same time, parasympathetic fibers innervating smooth muscles and glandular epithelium pass through the III, VII, IX and X nerves. Along the cranial nerves and their branches, sympathetic fibers can join them, which greatly complicates the anatomy of the pathways of innervation of the organs of the head and neck.
The nuclei of the cranial nerves are located mainly in the rhomboid brain (V, VI, VII, VIII, IX, X, XI, XII pairs); in the cover of the legs of the brain, in the midbrain, there are nuclei of III and IV pairs, as well as one nucleus of the V pair; I and II pairs of cranial nerves are connected with the diencephalon (Fig. 225).
0 para - terminal nerves
Terminal nerve (null pair)(n. terminalis) are a pair of small nerves that are closely adjacent to the olfactory nerves. They were first discovered in lower vertebrates, but their presence has been shown in human fetuses and adults. They contain many unmyelinated fibers and associated small groups of bipolar and multipolar nerve cells. Each nerve runs along the medial side of the olfactory tract, their branches pierce the ethmoid plate of the ethmoid bone and branch out in the nasal mucosa. Centrally, the nerve is connected to the brain near the anterior perforated space and the septum pellucidum. Its function is unknown, but presumably it represents the head of the sympathetic nervous system, which extends to the blood vessels and glands of the nasal mucosa. There is also an opinion that this nerve is specialized for the perception of pheromones.
I pair - olfactory nerves
Olfactory nerve(n. olfactorius) educated 15-20 olfactory filaments (fila olfactoria), which consist of nerve fibers - processes of olfactory cells located in the mucous membrane of the upper part of the nasal cavity (Fig. 226). Olfactory threads
Rice. 225.The nuclei of the cranial nerves in the brain stem, rear view: 1 - oculomotor nerve; 2 - red core; 3 - motor nucleus of the oculomotor nerve; 4 - additional autonomous nucleus of the oculomotor nerve; 5 - the motor nucleus of the block nerve; 6 - block nerve; 7 - the motor nucleus of the trigeminal nerve; 8, 30 - trigeminal nerve and node; 9 - abducens nerve; 10 - the motor nucleus of the facial nerve; 11 - knee of the facial nerve; 12 - upper and lower salivary nuclei; 13, 24 - glossopharyngeal nerve; 14, 23 - vagus nerve; 15 - accessory nerve; 16 - double core; 17, 20 - dorsal nucleus of the vagus nerve; 18 - the nucleus of the hypoglossal nerve; 19 - spinal nucleus of the accessory nerve; 21 - the core of a single beam; 22 - spinal tract of the trigeminal nerve; 25 - nuclei of the vestibular nerve; 26 - nuclei of the cochlear nerve; 27 - vestibulocochlear nerve; 28 - facial nerve and knee node; 29 - the main sensory nucleus of the trigeminal nerve; 31 - mesencephalic trigeminal nucleus
Rice. 226. Olfactory nerve (diagram):
I - subcalcified field; 2 - partition field; 3 - anterior commissure; 4 - medial olfactory strip; 5 - parahippocampal gyrus; 6 - dentate gyrus; 7 - fringes of the hippocampus; 8 - hook; 9 - amygdala; 10 - anterior perforated substance; 11 - lateral olfactory strip; 12 - olfactory triangle; 13 - olfactory tract; 14 - ethmoid plate of the ethmoid bone; 15 - olfactory bulb; 16 - olfactory nerve; 17 - olfactory cells; 18 - mucous membrane of the olfactory region
enter the cranial cavity through a hole in the cribriform plate and end at the olfactory bulbs, which continue into olfactory tract (tractus olfactorius)(see fig. 222).
IIpair - optic nerves
optic nerve(n. opticus) consists of nerve fibers formed by the processes of multipolar nerve cells of the retina of the eyeball (Fig. 227). The optic nerve is formed in the posterior hemisphere of the eyeball and passes in the orbit to the optic canal, from where it exits into the cranial cavity. Here, in the precross sulcus, both optic nerves are connected, forming visual decussation (chiasma opticum). The continuation of the visual pathways is called the optic tract. (tractus opticus). At the optic chiasm, the medial group of nerve fibers of each nerve passes into the optic tract of the opposite side, and the lateral group continues into the corresponding optic tract. The visual tracts reach the subcortical visual centers (see Fig. 222).
Rice. 227. Optic nerve (diagram).
The fields of view of each eye are superimposed on one another; the dark circle in the center corresponds to the yellow spot; each quadrant has its own color: 1 - projection onto the retina of the right eye; 2 - optic nerves; 3 - optic chiasm; 4 - projection on the right geniculate body; 5 - visual tracts; 6, 12 - visual radiance; 7 - lateral cranked bodies; 8 - projection onto the cortex of the right occipital lobe; 9 - spur furrow; 10 - projection onto the cortex of the left occipital lobe; 11 - projection on the left geniculate body; 13 - projection on the retina of the left eye
III pair - oculomotor nerves
oculomotor nerve(n. oculomotorius) mainly motor, originates in the motor nucleus (nucleus nervi oculomotorii) midbrain and visceral autonomous accessory nuclei (nuclei visceralis accessorii n. oculomotorii). It comes to the base of the brain at the medial edge of the brain stem and goes forward in the upper wall of the cavernous sinus to the superior orbital fissure, through which it enters the orbit and is divided into upper branch (r. superior) - to the superior rectus muscle and the muscle that lifts the eyelid, and the lower branch (r. inferior)- to the medial and lower straight and lower oblique muscles (Fig. 228). A branch departs from the lower branch to the ciliary node, which is its parasympathetic root.
Rice. 228. Oculomotor nerve, lateral view: 1 - ciliary node; 2 - nasociliary root of the ciliary node; 3 - the upper branch of the oculomotor nerve; 4 - nasociliary nerve; 5 - ophthalmic nerve; 6 - oculomotor nerve; 7 - block nerve; 8 - accessory nucleus of the oculomotor nerve; 9 - motor nucleus of the oculomotor nerve; 10 - the nucleus of the trochlear nerve; 11 - abducens nerve; 12 - lateral rectus muscle of the eye; 13 - lower branch of the oculomotor nerve; 14 - medial rectus muscle of the eye; 15 - lower rectus muscle of the eye; 16 - oculomotor root of the ciliary node; 17 - lower oblique muscle of the eye; 18 - ciliary muscle; 19 - pupil dilator, 20 - pupil sphincter; 21 - upper rectus muscle of the eye; 22 - short ciliary nerves; 23 - long ciliary nerve
IVpara-trochlear nerves
Block nerve(n. trochlearis) motor, originates in the motor nucleus (nucleus n. trochlearis), located in the midbrain at the level of the inferior colliculus. It comes to the base of the brain outward from the bridge and continues forward in the outer wall of the cavernous sinus. Through the superior orbital fissure flows into the orbit and branches in the superior oblique muscle (Fig. 229).
Vpara - trigeminal nerves
Trigeminal nerve(n. trigeminus) is mixed and contains motor and sensory nerve fibers. Innervates masticatory muscles, skin of the face and anterior part of the head, hard shell of the brain, as well as mucous membranes of the nasal and oral cavities, teeth.
The trigeminal nerve has a complex structure. It distinguishes
(Fig. 230, 231):
1) nuclei (one motor and three sensitive);
2) sensitive and motor roots;
3) trigeminal knot on a sensitive spine;
4) 3 main branches of the trigeminal nerve: ocular, maxillary And mandibular nerve.
Sensory nerve cells, the peripheral processes of which form the sensory branches of the trigeminal nerve, are located in trigeminal node, ganglion trigeminale. The trigeminal knot rests on trigeminal depression, inpressio trigeminalis, anterior surface of the pyramid of the temporal bone trigeminal cavity (cavum trigeminale), formed by the dura mater. The node is flat, crescent-shaped, 9-24 mm long (frontal size) and 3-7 mm wide (sagittal size). In people with a brachycephalic skull, the nodes are large, in the form of a straight line, while in dolichocephals they are small, in the form of an open circle.
The cells of the trigeminal node are pseudo-unipolar, i.e. give one process, which near the cell body is divided into central and peripheral. The central processes form sensitive spine (radix sensorial) and through it they enter the brain stem, reaching the sensitive nuclei of the nerve: main nucleus (nucleus principalis nervi trigemini)- in the bridge and spinal nucleus (nucleus spinalis nervi trigemini) - in the lower part of the bridge, in the medulla oblongata and in the cervical segments of the spinal cord. In the midbrain is mesencephalic trigeminal nucleus (nucleus mesencephalicus
Rice. 229. Nerves of the orbit, dorsal view. (The upper wall of the orbit is removed): 1 - supraorbital nerve; 2 - muscle that lifts the upper eyelid; 3 - upper rectus muscle of the eye; 4 - lacrimal gland; 5 - lacrimal nerve; 6 - lateral rectus muscle of the eye; 7 - frontal nerve; 8 - maxillary nerve; 9 - mandibular nerve; 10 - trigeminal knot; 11 - a hint of the cerebellum; 12 - abducens nerve; 13, 17 - trochlear nerve; 14 - oculomotor nerve; 15 - optic nerve; 16 - ophthalmic nerve; 18 - nasociliary nerve; 19 - subblock nerve; 20 - upper oblique muscle of the eye; 21 - medial rectus muscle of the eye; 22 - supratrochlear nerve
Rice. 230. Trigeminal nerve (diagram):
1 - midbrain nucleus; 2 - the main sensitive core; 3 - spinal tract; 4 - facial nerve; 5 - mandibular nerve; 6 - maxillary nerve; 7 - ophthalmic nerve; 8 - trigeminal nerve and node; 9 - motor nucleus. Red solid line indicates motor fibers; solid blue line - sensitive fibers; blue dotted line - proprioceptive fibers; red dotted line - parasympathetic fibers; red dashed line - sympathetic fibers
nervi trigemini). This nucleus consists of pseudo-unipolar neurons and is believed to be related to the proprioceptive innervation of the muscles of the face and masticatory muscles.
The peripheral processes of the neurons of the trigeminal ganglion are part of the listed main branches of the trigeminal nerve.
Motor nerve fibers originate in motor nucleus of the nerve (nucleus motorius nervi trigemini), at the back of the bridge. These fibers leave the brain and form motor root (radix motoria). The exit point of the motor root from the brain and the entrance of the sensitive one is located at the transition of the bridge to the middle cerebellar peduncle. Between the sensory and motor roots of the trigeminal nerve, there is often (in 25% of cases)
Rice. 231. Trigeminal nerve, lateral view. (The lateral wall of the orbit and part of the lower jaw are removed):
1 - trigeminal node; 2 - large stony nerve; 3 - facial nerve; 4 - mandibular nerve; 5 - ear-temporal nerve; 6 - lower alveolar nerve; 7 - lingual nerve; 8 - buccal nerve; 9 - pterygopalatine node; 10 - infraorbital nerve; 11 - zygomatic nerve; 12 - lacrimal nerve; 13 - frontal nerve; 14 - ophthalmic nerve; 15 - maxillary nerve
anastomotic connections, as a result of which a certain number of nerve fibers pass from one root to another.
The diameter of the sensitive root is 2.0-2.8 mm, it contains from 75,000 to 150,000 myelinated nerve fibers with a diameter mainly up to 5 microns. The thickness of the motor root is less - 0.8-1.4 mm. It contains from 6,000 to 15,000 myelinated nerve fibers with a diameter, usually more than 5 microns.
The sensory root with its trigeminal node and the motor root together make up the trunk of the trigeminal nerve with a diameter of 2.3-3.1 mm, containing from 80,000 to 165,000 myelinated nerve fibers. The motor root bypasses the trigeminal ganglion and enters the mandibular nerve.
Parasympathetic nerve nodes are connected with 3 main branches of the trigeminal nerve: the ciliary node - with the ophthalmic nerve, the pterygopalatine node - with the maxillary, ear, submandibular and sublingual nodes - with the mandibular nerves.
The general plan for dividing the main branches of the trigeminal nerve is as follows: each nerve (ophthalmic, maxillary and mandibular) gives off a branch to the dura mater; visceral branches - to the mucous membrane of the accessory sinuses, oral and nasal cavities and organs (lacrimal gland, eyeball, salivary glands, teeth); external branches, among which medial ones are distinguished - to the skin of the anterior regions of the face and lateral - to the skin of the lateral regions of the face.
ophthalmic nerve
ophthalmic nerve(n. ophthalmicus) is the first, thinnest branch of the trigeminal nerve. It is sensitive and innervates the skin of the forehead and the anterior part of the temporal and parietal regions, the upper eyelid, the back of the nose, and also partially the mucous membrane of the nasal cavity, the membranes of the eyeball and the lacrimal gland (Fig. 232).
The nerve is 2-3 mm thick, consists of 30-70 relatively small bundles and contains from 20,000 to 54,000 myelinated nerve fibers, mostly of small diameter (up to 5 microns). Upon departure from the trigeminal node, the nerve passes in the outer wall of the cavernous sinus, where it gives return shell (tentorial) branch (r. meningeus recurrens (tentorius) to the cerebellum. Near the superior orbital fissure, the optic nerve divides into 3 branches: lacrimal, frontal And nasociliary nerves.
Rice. 232. Nerves of the orbit, dorsal view. (Partially removed the muscle that lifts the upper eyelid, and the upper rectus and upper oblique muscles of the eye): 1 - long ciliary nerves; 2 - short ciliary nerves; 3, 11 - lacrimal nerve; 4 - ciliary knot; 5 - oculomotor root of the ciliary node; 6 - additional oculomotor root of the ciliary node; 7 - nasociliary root of the ciliary node; 8 - branches of the oculomotor nerve to the lower rectus muscle of the eye; 9, 14 - abducens nerve; 10 - lower branch of the oculomotor nerve; 12 - frontal nerve; 13 - ophthalmic nerve; 15 - oculomotor nerve; 16 - block nerve; 17 - branch of the cavernous sympathetic plexus; 18 - nasociliary nerve; 19 - the upper branch of the oculomotor nerve; 20 - posterior ethmoid nerve; 21 - optic nerve; 22 - anterior lattice nerve; 23 - subblock nerve; 24 - supraorbital nerve; 25 - supratrochlear nerve
1. Lacrimal nerve(n. lacrimalis) located near the outer wall of the orbit, where it receives connecting branch with the zygomatic nerve (r. communicans cum nervo zygomatico). Provides sensitive innervation of the lacrimal gland, as well as the skin of the upper eyelid and lateral canthus.
2.frontal nerve(n. frontalis) - the thickest branch of the optic nerve. Passes under the upper wall of the orbit and is divided into two branches: supraorbital nerve (n. supraorbital), going through the supraorbital notch to the skin of the forehead, and supratrochlear nerve (n. supratrochlearis), emerging from the orbit at its inner wall and innervating the skin of the upper eyelid and medial corner of the eye.
3.Nasociliary nerve(n. nasociliaris) lies in the orbit near its medial wall and, under the block of the superior oblique muscle, leaves the orbit in the form of a terminal branch - subtrochlear nerve (n. infratrochlearis), which innervates the lacrimal sac, conjunctiva and medial angle of the eye. In its course, the nasociliary nerve gives off the following branches:
1)long ciliary nerves (nn. ciliares longi) to the eyeball;
2)posterior ethmoidal nerve (n. ethmoidalis posterior) to the mucous membrane of the sphenoid sinus and the posterior cells of the ethmoid labyrinth;
3)anterior ethmoid nerve (n. ethmoidalis anterior) to the mucous membrane of the frontal sinus and nasal cavity (rr. nasales interni laterales et mediales) and to the skin of the tip and wing of the nose.
In addition, a connecting branch departs from the nasociliary nerve to the ciliary ganglion.
eyelash knot(ganglion ciliare)(Fig. 233), up to 4 mm long, lies on the lateral surface of the optic nerve, approximately on the border between the posterior and middle thirds of the length of the orbit. In the ciliary node, as in other parasympathetic nodes of the trigeminal nerve, there are parasympathetic multi-processed (multipolar) nerve cells, on which preganglionic fibers, forming synapses, switch to postganglionic ones. Sensory fibers transit through the node.
Connecting branches in the form of its roots approach the node:
1)parasympathetic (radix parasympathica (oculomotoria) gangliiciliaris) - from the oculomotor nerve;
2)sensitive (radix sensorial (nasociliaris) ganglii ciliaris) - from the nasopharyngeal nerve.
From the ciliary node departs from 4 to 40 short ciliary nerves (nn. ciliares breves), going inside the eyeball. They contain postganglionic parasympathetic fibers that innervate the ciliary muscle, sphincter and, to a lesser extent, pupil dilator, as well as sensitive fibers to the membranes of the eyeball. (Sympathetic fibers to the dilator muscle are described below.)
Rice. 233. Ciliary knot (preparation of A.G. Tsybulkin). Impregnation with silver nitrate, clearing in glycerin. SW. x 12.
1 - ciliary knot; 2 - branch of the oculomotor nerve to the inferior oblique muscle of the eye; 3 - short ciliary nerves; 4 - ophthalmic artery; 5 - nasociliary root of the ciliary node; 6 - additional oculomotor roots of the ciliary node; 7 - oculomotor root of the ciliary node
maxillary nerve
maxillary nerve(n. maxillaries) - the second branch of the trigeminal nerve, sensitive. It has a thickness of 2.5-4.5 mm and consists of 25-70 small bundles containing from 30,000 to 80,000 myelinated nerve fibers, mostly of small diameter (up to 5 microns).
The maxillary nerve innervates the dura mater, the skin of the lower eyelid, the lateral angle of the eye, the anterior part of the temporal region, the upper part of the cheek, the wings of the nose, the skin and mucous membrane of the upper lip, the mucous membrane of the posterior and lower parts of the nasal cavity, the mucous membrane of the sphenoid sinus, and the palate. , teeth of the upper jaw. Upon exiting the skull through a round hole, the nerve enters the pterygopalatine fossa, passes from back to front and from the inside to the outside (Fig. 234). The length of the segment and its position in the fossa depend on the shape of the skull. With a brachycephalic skull, the length of the segment
the nerve in the fossa is 15-22 mm, it is located deep in the fossa - up to 5 cm from the middle of the zygomatic arch. Sometimes the nerve in the pterygopalatine fossa is covered by a bony crest. With a dolichocephalic skull, the length of the considered section of the nerve is 10-15 mm, it is located more superficially - up to 4 cm from the middle of the zygomatic arch.
Rice. 234. Maxillary nerve, lateral view. (The wall and contents of the orbit have been removed):
1 - lacrimal gland; 2 - zygomaticotemporal nerve; 3 - zygomaticofacial nerve; 4 - external nasal branches of the anterior ethmoid nerve; 5 - nasal branch; 6 - infraorbital nerve; 7 - anterior superior alveolar nerves; 8 - mucous membrane of the maxillary sinus; 9 - middle upper alveolar nerve; 10 - dental and gingival branches; 11 - upper dental plexus; 12 - infraorbital nerve in the canal of the same name; 13 - posterior superior alveolar nerves; 14 - nodal branches to the pterygopalatine node; 15 - large and small palatine nerves; 16 - pterygopalatine node; 17 - nerve of the pterygoid canal; 18 - zygomatic nerve; 19 - maxillary nerve; 20 - mandibular nerve; 21 - oval hole; 22 - round hole; 23 - meningeal branch; 24 - trigeminal nerve; 25 - trigeminal knot; 26 - ophthalmic nerve; 27 - frontal nerve; 28 - nasociliary nerve; 29 - lacrimal nerve; 30 - eyelash knot
Within the pterygo-palatine fossa, the maxillary nerve gives off meningeal branch (r. meningeus) to the dura mater and is divided into 3 branches:
1) nodal branches to the pterygopalatine node;
2) zygomatic nerve;
3) infraorbital nerve, which is a direct continuation of the maxillary nerve.
1. Nodal branches to the pterygopalatine node(rr. ganglionares ad ganglio pterygopalatinum)(1-7 in number) depart from the maxillary nerve at a distance of 1.0-2.5 mm from the round hole and go to the pterygopalatine node, giving sensory fibers to the nerves starting from the node. Some nodal branches bypass the node and join its branches.
Pterygopalatine node(ganglion pterygopalatinum) - formation of the parasympathetic part of the autonomic nervous system. The node is triangular in shape, 3-5 mm long, contains multipolar cells and has 3 roots:
1) sensitive - nodal branches;
2) parasympathetic - great stony nerve (n. petrosus major)(branch of the intermediate nerve), contains fibers to the glands of the nasal cavity, palate, lacrimal gland;
3) sympathetic - deep stony nerve (n. petrosus profundus) departs from the internal carotid plexus, contains postganglionic sympathetic nerve fibers from the cervical nodes. As a rule, the large and deep stony nerves are connected to the nerve of the pterygoid canal, passing through the canal of the same name at the base of the pterygoid process of the sphenoid bone.
Branches depart from the node, which include secretory and vascular (parasympathetic and sympathetic) and sensory fibers (Fig. 235):
1)orbital branches (rr. orbitales), 2-3 thin trunks penetrate through the inferior orbital fissure and then, together with the posterior ethmoid nerve, go through the small holes of the sphenoid-ethmoid suture to the mucous membrane of the posterior cells of the ethmoid labyrinth and sphenoid sinus;
2)posterior superior nasal branches (rr. nasales posteriores superiors)(8-14 in number) exit the pterygopalatine fossa through the sphenopalatine opening into the nasal cavity and are divided into two groups: lateral and medial (Fig. 236). Lateral branches
Rice. 235. Pterygopalatine node (diagram):
1 - upper salivary nucleus; 2 - facial nerve; 3 - knee of the facial nerve; 4 - large stony nerve; 5 - deep stony nerve; 6 - nerve of the pterygoid canal; 7 - maxillary nerve; 8 - pterygopalatine node; 9 - posterior superior nasal branches; 10 - infraorbital nerve; 11 - nasopalatine nerve; 12 - postganglionic autonomic fibers to the mucous membrane of the nasal cavity; 13 - maxillary sinus; 14 - posterior superior alveolar nerves; 15 - large and small palatine nerves; 16 - tympanic cavity; 17 - internal carotid nerve; 18 - internal carotid artery; 19 - upper cervical node of the sympathetic trunk; 20 - autonomous nuclei of the spinal cord; 21 - sympathetic trunk; 22 - spinal cord; 23 - medulla oblongata
(rr. nasales posteriores superiores laterales)(6-10), go to the mucous membrane of the posterior sections of the superior and middle turbinates and nasal passages, the posterior cells of the ethmoid bone, the upper surface of the choanae and the pharyngeal opening of the auditory tube. Medial branches (rr. nasales posteriores superiores mediales)(2-3), branch out in the mucous membrane of the upper part of the nasal septum. One of the medial branches nasopalatine nerve (n. nasopalatinus) - passes between the periosteum and the mucosa
Rice. 236. Nasal branches of the pterygopalatine node, view from the side of the nasal cavity: 1 - olfactory filaments; 2, 9 - nasopalatine nerve in the incisive canal; 3 - posterior superior medial nasal branches of the pterygopalatine node; 4 - posterior upper lateral nasal branches; 5 - pterygopalatine node; 6 - posterior lower nasal branches; 7 - small palatine nerve; 8 - large palatine nerve; 10 - nasal branches of the anterior ethmoid nerve
septum together with the posterior artery of the nasal septum forward, to the nasal opening of the incisive canal, through which it reaches the mucous membrane of the anterior part of the palate (Fig. 237). Forms a connection with the nasal branch of the superior alveolar nerve.
3) palatine nerves (nn. palatine) spread from the node through the large palatine canal, forming 3 groups of nerves:
Rice. 237. Sources of innervation of the palate, bottom view (soft tissues removed): 1 - nasopalatine nerve; 2 - large palatine nerve; 3 - small palatine nerve; 4 - soft palate
1)great palatine nerve (n. palatinus major) - the thickest branch, goes through the large palatine opening to the palate, where it breaks up into 3-4 branches, innervating most of the mucous membrane of the palate and its glands in the area from the fangs to the soft palate;
2)small palatine nerves (nn. palatini minores) enter the oral cavity through the small palatine openings and branch in the mucous membrane of the soft palate and the region of the palatine tonsil;
3)lower posterior nasal branches (rr. nasales posteriores inferiors) enter the greater palatine canal, leave it through small openings and enter the nasal cavity at the level of the inferior nasal concha, innervating the mucous membrane of the inferior concha, middle and lower nasal passages and maxillary sinus.
2. Zygomatic nerve(n. zygomaticus) branches off from the maxillary nerve within the pterygo-palatine fossa and penetrates through the inferior orbital fissure into the orbit, where it goes along the outer wall, gives off a connecting branch to the lacrimal nerve, containing secretory parasympathetic fibers to the lacrimal gland, enters the zygomatic-orbital foramen and inside the zygomatic bone is divided into two branches:
1)zygomaticofacial branch (r. zygomaticofacialis ), which exits through the zygomatic-facial opening to the anterior surface of the zygomatic bone; in the skin of the upper part of the cheek, it gives off a branch to the area of the outer canthus and a connecting branch to the facial nerve;
2)zygomaticotemporal branch (r. zygomaticotemporalis ), which exits the orbit through the opening of the zygomatic bone of the same name, perforates the temporal muscle and its fascia, and innervates the skin of the anterior part of the temporal and posterior parts of the frontal regions.
3. Infraorbital nerve(n. infraorbitalis ) is a continuation of the maxillary nerve and gets its name after the above-mentioned branches depart from it. The infraorbital nerve leaves the pterygopalatine fossa through the inferior orbital fissure, passes along the lower wall of the orbit along with the vessels of the same name in the infraorbital sulcus (in 15% of cases, there is a bone canal instead of the sulcus) and exits through the infraorbital foramen under the muscle that lifts the upper lip, dividing into terminal branches. The length of the infraorbital nerve is different: with brachycephaly, the nerve trunk is 20-27 mm, and with dolichocephaly - 27-32 mm. The position of the nerve in the orbit corresponds to the parasagittal plane drawn through the infraorbital foramen.
The branching can also be different: scattered, in which numerous thin nerves with many connections depart from the trunk, or main, with a small number of large nerves. On its way, the infraorbital nerve gives off the following branches:
1) superior alveolar nerves (nn. alveolares superiors) innervate the teeth and upper jaw (see Fig. 235). There are 3 groups of branches of the superior alveolar nerves:
1) posterior superior alveolar branches (rr. alveolares superiores posteriors) branch off from the infraorbital nerve, as a rule, in the pterygo-palatine fossa, 4-8 in number and are located along with the vessels of the same name along the surface of the tubercle of the upper jaw. Part of the most posterior nerves goes along the outer surface of the tubercle down to the alveolar process, the rest enter through the posterior superior alveolar openings into the alveolar canals. Branching together with other upper alveolar branches, they form the nervous superior dental plexus (plexus dentalis superior), which lies in the alveolar process of the upper jaw above the tops of the roots. The plexus is dense, wide-looped, stretched along the entire length of the alveolar process. depart from the plexus upper gums
high branches (rr. gingivales superiors) to the periodontium and periodontium in the area of the upper molars and upper dental branches (rr. dentales superiors) - to the tops of the roots of large molars, in the pulp cavity of which they branch out. In addition, the posterior superior alveolar rami send fine nerves to the mucosa of the maxillary sinus;
2)middle upper alveolar branch (r. alveolaris superior) in the form of one or (rarely) two trunks, it branches off from the infraorbital nerve, more often in the pterygo-palatine fossa and (less often) within the orbit, passes in one of the alveolar canals and branches in the bone canals of the upper jaw as part of the superior dental plexus. It has connecting branches with posterior and anterior superior alveolar branches. Innervates through the upper gingival branches the periodontium and periodontium in the area of the upper premolars and through the upper dental branches - the upper premolars;
3)anterior superior alveolar branches (rr. alveolares superiores anteriores) arise from the infraorbital nerve in the anterior part of the orbit, which they leave through the alveolar canals, penetrating into the anterior wall of the maxillary sinus, where they are part of the superior dental plexus. Upper gingival branches innervate the mucous membrane of the alveolar process and the walls of the alveoli in the area of the upper canines and incisors, upper dental branches- upper canines and incisors. The anterior superior alveolar branches send a thin nasal branch to the mucosa of the anterior floor of the nasal cavity;
2)lower rami of the eyelids (rr. palpebrales inferiors) branches off from the infraorbital nerve at the exit from the infraorbital foramen, penetrates through the muscle that raises the upper lip, and, branching, innervates the skin of the lower eyelid;
3)external nasal branches (rr. nasales superiors) innervate the skin in the wing of the nose;
4)internal nasal branches (rr. nasales interni) approach the mucous membrane of the vestibule of the nasal cavity;
5)superior labial branches (rr. labiales superiors)(number 3-4) go between the upper jaw and the muscle that raises the upper lip, down; innervate the skin and mucous membrane of the upper lip to the corner of the mouth.
All of these external branches of the infraorbital nerve form connections with the branches of the facial nerve.
Mandibular nerve
Mandibular nerve(n. mandibularis) - the third branch of the trigeminal nerve is a mixed nerve and is formed by sensory nerve fibers coming from the trigeminal ganglion and motor fibers of the motor root (Fig. 238, 239). The thickness of the nerve trunk ranges from 3.5 to 7.5 mm, and the length of the extracranial part of the trunk is 0.5-2.0 cm. The nerve consists of 30-80 fiber bundles, including from 50,000 to 120,000 myelinated nerve fibers.
The mandibular nerve carries out sensitive innervation of the hard shell of the brain, the skin of the lower lip, chin, lower cheek, anterior part of the auricle and external auditory canal, part of the surface of the tympanic membrane, buccal mucosa, floor of the mouth and the anterior two-thirds of the tongue, teeth of the lower jaw , as well as the motor innervation of all the masticatory muscles, the maxillofacial muscle, the anterior belly of the digastric muscle and the muscles that strain the eardrum and the palatine curtain.
The mandibular nerve exits the cranial cavity through the foramen ovale and enters the infratemporal fossa, where it divides near the point of exit into a number of branches. Branching of the mandibular nerve is possible or loose type(more often with dolichocephaly) - the nerve splits into many branches (8-11), or along trunk type(more often with brachycephaly) with branching into a small number of trunks (4-5), each of which is common to several nerves.
Three nodes of the autonomic nervous system are associated with the branches of the mandibular nerve: ear(ganglion oticum);submandibular(ganglion submandibulare);sublingual(ganglion sublinguale). From the nodes go postganglionic parasympathetic secretory fibers to the salivary glands.
The mandibular nerve gives off a number of branches.
1.Meningeal branch(r. meningeus) passes through the foramen spinosa together with the middle meningeal artery into the cranial cavity, where it branches into the dura mater.
2.chewing nerve(n. massetericus), predominantly motor, often (especially with the main form of branching of the mandibular nerve) has a common origin with other nerves of the masticatory muscles. Passes outwards over the upper edge of the lateral pterygoid muscle, then through the notch of the lower jaw and is introduced into the masticatory muscle. Before entering the muscle sends a thin branch
Rice. 238. Mandibular nerve, left view. (Mandibular branch removed):
1 - ear-temporal nerve; 2 - middle meningeal artery; 3 - superficial temporal artery; 4 - facial nerve; 5 - maxillary artery; 6 - lower alveolar nerve; 7 - maxillofacial nerve; 8 - submandibular node; 9 - internal carotid artery; 10 - mental nerve; 11 - medial pterygoid muscle; 12 - lingual nerve; 13 - drum string; 14 - buccal nerve; 15 - nerve to the lateral pterygoid muscle; 16 - pterygopalatine node; 17 - infraorbital nerve; 18 - maxillary nerve; 19 - zygomaticofacial nerve; 20 - nerve to the medial pterygoid muscle; 21 - mandibular nerve; 22 - chewing nerve; 23 - deep temporal nerves; 24 - zygomaticotemporal nerve
Rice. 239. Mandibular nerve, medial view: 1 - motor root; 2 - sensitive root; 3 - large stony nerve; 4 - small stony nerve; 5 - nerve to the muscle straining the eardrum; 6, 12 - drum string; 7 - ear-temporal nerve; 8 - lower alveolar nerve; 9 - maxillofacial nerve; 10 - lingual nerve; 11 - medial pterygoid nerve; 13 - ear knot; 14 - nerve to the muscle that strains the palatine curtain; 15 - mandibular nerve; 16 - maxillary nerve; 17 - ophthalmic nerve; 18 - trigeminal knot
to the temporomandibular joint, providing its sensitive innervation.
3.Deep temporal nerves(nn. temporales profundi), motor, pass along the outer base of the skull outward, bend around the infratemporal crest and enter the temporal muscle from its inner surface in the anterior (n. temporalis profundus anterior) and back (n. temporalis profundus posterior) departments.
4.Lateral pterygoid nerve(n. pterygoideus lateralis) motor, usually departs in a common trunk with the buccal nerve, approaches the muscle of the same name, in which it branches.
5.medial pterygoid nerve(n. pterygoideus medialis), mainly motor. It passes through the ear node or is adjacent to its surface and follows forward and downward to the inner surface of the muscle of the same name, into which it penetrates near its upper edge. In addition, near the ear node, he gives nerve to the muscle that strains the palatine curtain (n. musculi tensoris veli palatine), nerve to the muscle that strains the eardrum (n. musculi tensoris tympani), and a connecting branch to the node.
6.buccal nerve(n. buccalis), sensitive, penetrates between the two heads of the lateral pterygoid muscle and goes along the inner surface of the temporal muscle, spreading further along with the buccal vessels along the outer surface of the buccal muscle to the corner of the mouth. On its way, it gives off thin branches that pierce the buccal muscle and innervate the mucous membrane of the cheek (up to the gums of the 2nd premolar and 1st molar) and branches to the skin of the cheek and corner of the mouth. Forms a connecting branch with a branch of the facial nerve and with the ear node.
7.Auriculotemporal nerve(n. auriculotemporalis ), sensitive, starts from the posterior surface of the mandibular nerve with two roots covering the middle meningeal artery, which then join into a common trunk. Receives from the ear node a connecting branch containing parasympathetic fibers. Near the neck of the articular process of the lower jaw, the auricular-temporal nerve goes up and through the parotid salivary gland exits into the temporal region, where it branches into terminal branches - superficial temporal (rr. temporales superficiales). On its way, the ear-temporal nerve gives off the following branches:
1)articular (rr. articulares), to the temporomandibular joint;
2)parotid (rr. parotidei), to the parotid salivary gland. These branches contain, in addition to sensitive, parasympathetic secretory fibers from the ear node;
3)nerve of the external auditory canal (n. meatus acustuci externi), to the skin of the external auditory canal and eardrum;
4)anterior ear nerves (nn. auriculares anteriores), to the skin of the anterior part of the auricle and the middle part of the temporal region.
8.lingual nerve(n. lingualis), sensitive. It originates from the mandibular nerve near the foramen ovale and is located between the pterygoid muscles anterior to the inferior alveolar nerve. At the upper edge of the medial pterygoid muscle or slightly lower, it joins the nerve drum string (chorda tympani), which is a continuation of the intermediate nerve.
As part of the drum string, secretory fibers are included in the lingual nerve, following to the submandibular and hypoglossal nerve nodes, and taste fibers to the papillae of the tongue. Further, the lingual nerve passes between the inner surface of the lower jaw and the medial pterygoid muscle, above the submandibular salivary gland along the outer surface of the hyoid-lingual muscle to the lateral surface of the tongue. Between the hyoid-lingual and genio-lingual muscles, the nerve breaks up into terminal lingual branches (rr. linguales).
Along the course of the nerve, connecting branches form with the hypoglossal nerve and the tympanic string. In the oral cavity, the lingual nerve gives off the following branches:
1)branches to the isthmus of the pharynx (rr. isthmi faucium), innervating the mucous membrane of the pharynx and the posterior part of the floor of the mouth;
2)hypoglossal nerve (n. sublingualis) departs from the lingual nerve at the posterior edge of the hyoid node in the form of a thin connecting branch and extends forward along the lateral surface of the hyoid salivary gland. Innervates the mucous membrane of the bottom of the mouth, gums and sublingual salivary gland;
3)lingual branches (rr. linguales) pass along with the deep artery and veins of the tongue through the muscles of the tongue forward and end in the mucous membrane of the apex of the tongue and its body to the boundary line. As part of the lingual branches, taste fibers pass to the papillae of the tongue, passing from the drum string.
9. inferior alveolar nerve(n. alveolaris inferior) mixed. This is the largest branch of the mandibular nerve. Its trunk lies between the pterygoid muscles behind and lateral to the lingual nerve, between the mandible and the sphenomandibular ligament. The nerve enters, together with the vessels of the same name, into the mandibular canal, where it gives off multiple branches that anastomose with each other and form inferior dental plexus (plexus dentalis inferior)(in 15% of cases), or directly the lower dental and gingival branches. It leaves the canal through the mental foramen, dividing before entering the mental nerve and the incisive branch. Gives the following branches:
1) maxillofacial nerve (n. mylohyoides) arises near the entrance of the lower alveolar nerve into the mandibular foramen, is located in the sulcus of the same name of the branch of the lower jaw and goes to the maxillohyoid muscle and the anterior belly of the digastric muscle;
2)lower dental and gingival branches (rr. dentales et gingivales inferiors) originate from the inferior alveolar nerve in the mandibular canal; innervate the gums, alveoli of the alveolar part of the jaw and teeth (premolars and molars);
3)mental nerve (n. mentalis) is a continuation of the trunk of the lower alveolar nerve at the exit through the mental foramen from the mandibular canal; here the nerve is fan-shaped into 4-8 branches, among which there are chin (rr. mentales), to the skin of the chin and lower labials (rr. labials inferiors), to the skin and mucous membrane of the lower lip.
ear knot(ganglion oticum) - rounded flattened body with a diameter of 3-5 mm; located under the foramen ovale on the posteromedial surface of the mandibular nerve (Fig. 240, 241). A small stony nerve (from the glossopharyngeal) approaches it, bringing preganglionic parasympathetic fibers. A number of connecting branches depart from the node:
1) to the ear-temporal nerve, which receives postganglionic parasympathetic secretory fibers, which then go as part of the parotid branches to the parotid salivary gland;
2) to the buccal nerve, through which the postganglionic parasympathetic secretory fibers reach the small salivary glands of the oral cavity;
3) to the drum string;
4) to the pterygopalatine and trigeminal nodes.
Submandibular knot(ganglion submandibulare)(size 3.0-3.5 mm) is located under the trunk of the lingual nerve and is associated with it nodal branches (rr. ganglionares)(Fig. 242, 243). These branches lead to the node and terminate in it the preganglionic parasympathetic fibers of the tympanic string. Branches leaving the node innervate the submandibular and sublingual salivary glands.
Sometimes (up to 30% of cases) there is a separate sublingual node(ganglion sublingualis).
VI pair - abducens nerves
Abducens nerve (n. abducens - motor. Abducens nucleus (nucleus n. abducentis) located in the anterior part of the bottom of the IV ventricle. The nerve exits the brain at the posterior edge of the bridge, between it and the pyramid of the medulla oblongata, and soon outside the back of the Turkish saddle enters the cavernous sinus, where it is located along the outer surface of the internal carotid artery (Fig. 244). Further
Rice. 240. Autonomous nodes of the head, view from the medial side: 1 - nerve of the pterygoid canal; 2 - maxillary nerve; 3 - ophthalmic nerve; 4 - ciliary knot; 5 - pterygopalatine node; 6 - large and small palatine nerves; 7 - submandibular node; 8 - facial artery and nerve plexus; 9 - cervical sympathetic trunk; 10, 18 - internal carotid artery and nerve plexus; 11 - upper cervical node of the sympathetic trunk; 12 - internal carotid nerve; 13 - drum string; 14 - ear-temporal nerve; 15 - small stony nerve; 16 - ear knot; 17 - mandibular nerve; 19 - sensitive root of the trigeminal nerve; 20 - motor root of the trigeminal nerve; 21 - trigeminal node; 22 - large stony nerve; 23 - deep stony nerve
Rice. 241. The ear node of an adult (preparations of A.G. Tsybulkin): a - macromicropreparation, stained with Schiff's reagent, SW. x12: 1 - mandibular nerve in the foramen ovale (medial surface); 2 - ear knot; 3 - sensitive root of the ear node; 4 - connecting branches to the buccal nerve; 5 - additional ear nodes; 6 - connecting branches to the ear-temporal nerve; 7 - middle meningeal artery; 8 - small stony nerve; b - histotopogram, stained with hematoxylin-eosin, SW. X 10X 7
penetrates through the superior orbital fissure into the orbit and follows forward over the oculomotor nerve. Innervates the external rectus muscle of the eye.
VII pair - facial nerves
facial nerve(n. facialis) develops in connection with the formations of the second gill arch (see Fig. 223), so it innervates all the muscles of the face (mimic). The nerve is mixed, including motor fibers from its efferent nucleus, as well as sensory and autonomic (gustatory and secretory) fibers belonging to a closely related facial intermediate nerve(n. intermedins).
Motor nucleus of the facial nerve(nucleus n. facialis) located at the bottom of the IV ventricle, in the lateral region of the reticular formation. The facial nerve root emerges from the brain along with the intermediate nerve root anterior to the vestibulocochlear nerve, between
Rice. 242. Submandibular node, lateral view. (Most of the lower jaw removed):
1 - mandibular nerve; 2 - deep temporal nerves; 3 - buccal nerve; 4 - lingual nerve; 5 - submandibular node; 6 - submandibular salivary gland; 7 - maxillofacial nerve; 8 - lower alveolar nerve; 9 - drum string; 10 - ear-temporal nerve
the posterior margin of the pons and the olive of the medulla oblongata. Further, the facial and intermediate nerves enter the internal auditory opening and enter the canal of the facial nerve. Here, both nerves form a common trunk, making two turns corresponding to the bends of the canal (Fig. 245, 246).
First, the common trunk is located horizontally, heading anteriorly and laterally above the tympanic cavity. Then, according to the bend of the facial canal, the barrel turns at a right angle back, forming a knee (geniculum n. facialis) and knee joint (ganglion geniculi), belonging to the intermediate nerve. Having passed over the tympanic cavity, the trunk makes a second downward turn, located behind the cavity of the middle ear. In this area, the branches of the intermediate nerve depart from the common trunk, the facial nerve exits the canal
Rice. 243. Submandibular node (drug A.G. Tsybulkin): 1 - lingual nerve; 2 - nodal branches; 3 - submandibular node; 4 - glandular branches; 5 - submandibular salivary gland; 6 - branch of the submandibular node to the sublingual gland; 7 - submandibular duct
Rice. 244.Nerves of the oculomotor apparatus (diagram):
1 - superior oblique muscle of the eye; 2 - upper rectus muscle of the eye; 3 - block nerve; 4 - oculomotor nerve; 5 - lateral rectus muscle of the eye; 6 - lower rectus muscle of the eye; 7 - abducens nerve; 8 - lower oblique muscle of the eye; 9 - medial rectus muscle of the eye
Rice. 245. Facial nerve (diagram):
1 - internal carotid plexus; 2 - knee assembly; 3 - facial nerve; 4 - facial nerve in the internal auditory canal; 5 - intermediate nerve; 6 - the motor nucleus of the facial nerve; 7 - upper salivary nucleus; 8 - the core of a single path; 9 - occipital branch of the posterior auricular nerve; 10 - branches to the ear muscles; 11 - posterior ear nerve; 12 - nerve to the stirrup muscle; 13 - stylomastoid opening; 14 - tympanic plexus; 15 - tympanic nerve; 16 - glossopharyngeal nerve; 17 - posterior belly of the digastric muscle; 18 - stylohyoid muscle; 19 - drum string; 20 - lingual nerve (from the mandibular); 21 - submandibular salivary gland; 22 - sublingual salivary gland; 23 - submandibular node; 24 - pterygopalatine node; 25 - ear knot; 26 - nerve of the pterygoid canal; 27 - small stony nerve; 28 - deep stony nerve; 29 - large stony nerve
Rice. 246. Intraosseous part of the facial nerve trunk:
1 - large stony nerve; 2 - knot of the knee of the facial nerve; 3 - front channel; 4 - tympanic cavity; 5 - drum string; 6 - hammer; 7 - anvil; 8 - semicircular canaliculi; 9 - spherical bag; 10 - elliptical bag; 11 - node vestibule; 12 - internal auditory meatus; 13 - nuclei of the cochlear nerve; 14 - lower cerebellar peduncle; 15 - nuclei of the vestibular nerve; 16 - medulla oblongata; 17 - vestibulocochlear nerve; 18 - motor portion of the facial nerve and intermediate nerve; 19 - cochlear nerve; 20 - vestibular nerve; 21 - spiral ganglion
Rice. 247. Parotid plexus of the facial nerve:
a - main branches of the facial nerve, right side view: 1 - temporal branches; 2 - zygomatic branches; 3 - parotid duct; 4 - buccal branches; 5 - marginal branch of the lower jaw; 6 - cervical branch; 7 - digastric and stylohyoid branches;
8 - the main trunk of the facial nerve at the exit from the stylomastoid foramen;
9- posterior ear nerve; 10 - parotid salivary gland;
b - facial nerve and parotid gland in a horizontal section: 1 - medial pterygoid muscle; 2 - branch of the lower jaw; 3 - chewing muscle; 4 - parotid salivary gland; 5 - mastoid process; 6 - the main trunk of the facial nerve;
c - three-dimensional diagram of the relationship between the facial nerve and the parotid salivary gland: 1 - temporal branches; 2 - zygomatic branches; 3 - buccal branches; 4 - marginal branch of the lower jaw; 5 - cervical branch; 6 - lower branch of the facial nerve; 7 - digastric and stylohyoid branches of the facial nerve; 8 - the main trunk of the facial nerve; 9 - posterior ear nerve; 10 - the upper branch of the facial nerve
through the stylomastoid opening and soon enters the parotid salivary gland. The length of the trunk of the extracranial part of the facial nerve ranges from 0.8 to 2.3 cm (usually 1.5 cm), and the thickness is from 0.7 to 1.4 mm; the nerve contains 3500-9500 myelinated nerve fibers, among which thick ones predominate.
In the parotid salivary gland, at a depth of 0.5-1.0 cm from its outer surface, the facial nerve divides into 2-5 primary branches, which are divided into secondary ones, forming parotid plexus (plexus intraparotidus)(Fig. 247).
There are two forms of the external structure of the parotid plexus: reticular and main. At network form the nerve trunk is short (0.8-1.5 cm), in the thickness of the gland it is divided into many branches that have multiple connections with each other, as a result of which a narrow-loop plexus is formed. There are multiple connections with the branches of the trigeminal nerve. At trunk form the nerve trunk is relatively long (1.5-2.3 cm), divided into two branches (upper and lower), which give rise to several secondary branches; there are few connections between the secondary branches, the plexus is wide-looped (Fig. 248).
On its way, the facial nerve gives off branches when passing through the canal, as well as when leaving it. Inside the channel, a number of branches depart from it:
1.Greater stony nerve(n. petrosus major) originates near the node of the knee, leaves the canal of the facial nerve through the cleft of the canal of the large stony nerve and passes along the sulcus of the same name to the ragged foramen. Having penetrated through the cartilage to the outer base of the skull, the nerve connects to the deep petrosal nerve, forming pterygoid canal nerve (n. canalis pterygoidei), entering the pterygoid canal and reaching the pterygopalatine node.
The large stony nerve contains parasympathetic fibers to the pterygopalatine ganglion, as well as sensory fibers from the cells of the geniculate ganglion.
2.Stapes nerve(n. stapedius)- a thin trunk, branches off in the canal of the facial nerve at the second turn, penetrates the tympanic cavity, where it innervates the stapedius muscle.
3.drum string(chorda tympani) is a continuation of the intermediate nerve, separates from the facial nerve in the lower part of the canal above the stylomastoid foramen and enters through the tubule of the tympanic string into the tympanic cavity, where it lies under the mucous membrane between the long leg of the anvil and the handle of the malleus. Across
Rice. 248. Differences in the structure of the facial nerve:
a - network structure; b - main structure;
1 - facial nerve; 2 - chewing muscle
stony-tympanic fissure, the tympanic string goes to the outer base of the skull and merges with the lingual nerve in the infratemporal fossa.
At the point of intersection with the lower alveolar nerve, the drum string gives a connecting branch with the ear node. The string tympani consists of preganglionic parasympathetic fibers to the submandibular ganglion and taste-sensitive fibers to the anterior two-thirds of the tongue.
4. Connecting branch with tympanic plexus(r. communicans cum plexus tympanico) - thin branch; starts from the node of the knee or from the large stony nerve, passes through the roof of the tympanic cavity to the tympanic plexus.
Upon exiting the canal, the following branches depart from the facial nerve.
1.Posterior ear nerve(n. auricularis posterior) departs from the facial nerve immediately after exiting the stylomastoid foramen, goes back and up along the anterior surface of the mastoid process, dividing into two branches: ear (r. auricularis), innervates the posterior ear muscle, and occipital (r. occipitalis), innervates the occipital belly of the supracranial muscle.
2.Digastric branch(r. digasricus) arises slightly below the ear nerve and, going down, innervates the posterior belly of the digastric muscle and the stylohyoid muscle.
3.Connecting branch with glossopharyngeal nerve(r. communicans cum nervo glossopharyngeo) branches off near the stylomastoid foramen and extends anteriorly and down the stylo-pharyngeal muscle, connecting with the branches of the glossopharyngeal nerve.
Branches of the parotid plexus:
1.Temporal branches(rr. temporales)(2-4 in number) go up and are divided into 3 groups: anterior, innervating the upper part of the circular muscle of the eye, and the muscle wrinkling the eyebrow; medium, innervating the frontal muscle; back, innervating the vestigial muscles of the auricle.
2.zygomatic branches(rr. zygomatici)(number 3-4) spread forward and upward to the lower and lateral parts of the circular muscle of the eye and the zygomatic muscle, which innervate.
3.buccal branches(rr. buccales)(number 3-5) go horizontally anteriorly along the outer surface of the masticatory muscle and supply the branches of the muscle in the circumference of the nose and mouth.
4.Marginal branch of the lower jaw(r. marginalis mandibularis) runs along the edge of the lower jaw and innervates the muscles that lower the corner of the mouth and lower lip, the chin muscle and the muscle of laughter.
5. cervical branch(r. colli) descends to the neck, connects with the transverse nerve of the neck and innervates m. platysma.
Intermediate nerve(n. intermediate) consists of preganglionic parasympathetic and sensory fibers. Sensitive unipolar cells are located in the knee node. The central processes of the cells ascend as part of the nerve root and terminate in the nucleus of the solitary pathway. Peripheral processes of sensory cells go through the tympanic string and the large stony nerve to the mucous membrane of the tongue and soft palate.
Secretory parasympathetic fibers originate in the superior salivary nucleus in the medulla oblongata. The root of the intermediate nerve emerges from the brain between the facial and vestibulocochlear nerves, joins the facial nerve and goes in the canal of the facial nerve. The fibers of the intermediate nerve leave the trunk of the facial, passing into the tympanic string and the large stony nerve, reach the submandibular, hyoid and pterygopalatine nodes.
Questions for self-control
1. What cranial nerves are mixed?
2. What cranial nerves develop from the forebrain?
3. What nerves innervate the external muscles of the eye?
4. What branches depart from the optic nerve? Specify their areas of innervation.
5. What nerves innervate the upper teeth? Where do these nerves come from?
6. What branches of the mandibular nerve do you know?
7. What nerve fibers pass through the drum string?
8. What branches depart from the facial nerve inside its canal? What do they innervate?
9. What branches depart from the facial nerve in the region of the parotid plexus? What do they innervate?
VIII pair - vestibulocochlear nerves
Vestibulocochlear nerve(n. vestibulocochlearis)- sensitive, consists of two functionally different parts: vestibular And cochlear(see fig. 246).
Vestibular nerve (n. vestibularis) conducts impulses from the static apparatus of the vestibule and semicircular canals of the labyrinth of the inner ear. Cochlear nerve (n. cochlearis) provides the transmission of sound stimuli from the spiral organ of the cochlea. Each part of the nerve has its own sensory nodes containing bipolar nerve cells: the vestibulum - vestibulum(ganglion vestibulare) located at the bottom of the internal auditory canal; cochlear part - cochlear node (cochlear node), ganglion cochleare (ganglion spirale cochleare), which is in the snail.
The vestibular node is elongated, it distinguishes two parts: upper (pars superior) And lower (pars inferior). The peripheral processes of the cells of the upper part form the following nerves:
1)elliptic saccular nerve (n. utricularis), to the cells of the elliptical sac of the vestibule of the cochlea;
2)anterior ampullar nerve (n. ampularis anterior), to the cells of the sensitive strips of the anterior membranous ampulla of the anterior semicircular canal;
3)lateral ampullar nerve (n. ampularis lateralis), to the lateral membranous ampulla.
From the lower part of the vestibular node, peripheral processes of cells go in the composition spherical saccular nerve (n. saccularis)
Rice. 249. Vestibulocochlear nerve:
1 - elliptical saccular nerve; 2 - anterior ampullar nerve; 3 - posterior ampullar nerve; 4 - spherical-saccular nerve; 5 - lower branch of the vestibular nerve; 6 - the upper branch of the vestibular nerve; 7 - vestibular node; 8 - root of the vestibular nerve; 9 - cochlear nerve
Rice. 250. Glossopharyngeal nerve:
1 - tympanic nerve; 2 - knee of the facial nerve; 3 - lower salivary nucleus; 4 - double core; 5 - the core of a single path; 6 - the core of the spinal cord; 7, 11 - glossopharyngeal nerve; 8 - jugular opening; 9 - connecting branch to the ear branch of the vagus nerve; 10 - upper and lower nodes of the glossopharyngeal nerve; 12 - vagus nerve; 13 - upper cervical node of the sympathetic trunk; 14 - sympathetic trunk; 15 - sinus branch of the glossopharyngeal nerve; 16 - internal carotid artery; 17 - common carotid artery; 18 - external carotid artery; 19 - tonsil, pharyngeal and lingual branches of the glossopharyngeal nerve (pharyngeal plexus); 20 - stylo-pharyngeal muscle and nerve to it from the glossopharyngeal nerve; 21 - auditory tube; 22 - tubal branch of the tympanic plexus; 23 - parotid salivary gland; 24 - ear-temporal nerve; 25 - ear knot; 26 - mandibular nerve; 27 - pterygopalatine node; 28 - small stony nerve; 29 - nerve of the pterygoid canal; 30 - deep stony nerve; 31 - large stony nerve; 32 - carotid-tympanic nerves; 33 - stylomastoid opening; 34 - tympanic cavity and tympanic plexus
to the auditory spot of the sac and in the composition posterior ampullar nerve (n. ampularis posterior) to the posterior membranous ampulla.
The central processes of the cells of the vestibular ganglion form vestibular (upper) spine, which exits through the internal auditory opening behind the facial and intermediate nerves and enters the brain near the exit of the facial nerve, reaching 4 vestibular nuclei in the bridge: medial, lateral, superior and inferior.
From the cochlear node, the peripheral processes of its bipolar nerve cells go to the sensitive epithelial cells of the spiral organ of the cochlea, forming together the cochlear part of the nerve. The central processes of the cochlear ganglion cells form cochlear (lower) spine, going along with the upper root to the brain to the dorsal and ventral cochlear nuclei.
IX pair - glossopharyngeal nerves
Glossopharyngeal nerve(n. glossopharyngeus) - nerve of the third gill arch, mixed. It innervates the mucous membrane of the posterior third of the tongue, the palatine arches, the pharynx and the tympanic cavity, the parotid salivary gland and the stylo-pharyngeal muscle (Fig. 249, 250). There are 3 types of nerve fibers in the composition of the nerve:
1) sensitive;
2) motor;
3) parasympathetic.
Sensitive fibers - outgrowths of afferent cells top And bottom nodes (ganglia superior et inferior). The peripheral processes follow as part of the nerve to the organs where they form receptors, the central ones go to the medulla oblongata, to the sensitive the nucleus of the solitary path (nucleus tractus solitarii).
motor fibers originate from nerve cells in common with the vagus nerve double nucleus (nucleus ambiguous) and pass as part of the nerve to the stylo-pharyngeal muscle.
Parasympathetic fibers originate in the autonomic parasympathetic lower salivary nucleus (nucleus salivatorius superior), which is located in the medulla oblongata.
The glossopharyngeal nerve root emerges from the medulla oblongata behind the exit site of the vestibulocochlear nerve and, together with the vagus nerve, leaves the skull through the jugular foramen. In this hole, the nerve has the first expansion - top node (ganglion superior), and at the exit from the hole - the second expansion - bottom knot (ganglion inferior).
Outside the skull, the glossopharyngeal nerve lies first between the internal carotid artery and the internal jugular vein, and then in a gentle arc it goes around the back and outside of the stylo-pharyngeal muscle and comes from the inside of the hyoid-lingual muscle to the root of the tongue, dividing into terminal branches.
Branches of the glossopharyngeal nerve.
1.Tympanic nerve(n. tympanicus) branches off from the lower node and passes through the tympanic canaliculus into the tympanic cavity, where it forms together with the carotid-tympanic nerves tympanic plexus (plexus tympanicus). The tympanic plexus innervates the mucous membrane of the tympanic cavity and the auditory tube. The tympanic nerve leaves the tympanic cavity through its superior wall as small stony nerve (n. petrosus minor) and goes to the ear node. Preganglionic parasympathetic secretory fibers, suitable as part of the small stony nerve, are interrupted in the ear node, and postganglionic secretory fibers enter the ear-temporal nerve and reach the parotid salivary gland in its composition.
2.Branch of the stylo-pharyngeal muscle(r. m. stylopharyngei) goes to the muscle of the same name and the mucous membrane of the pharynx.
3.sinus branch(r. sinus carotici) sensitive, branches in the sleepy glomus.
4.almond branches(rr. tonsillares) are sent to the mucous membrane of the palatine tonsil and arches.
5.Pharyngeal branches(rr. pharyngei)(3-4 in number) approach the pharynx and, together with the pharyngeal branches of the vagus nerve and the sympathetic trunk, form on the outer surface of the pharynx pharyngeal plexus (plexus pharyngealis). Branches depart from it to the muscles of the pharynx and to the mucous membrane, which, in turn, form intramural nerve plexuses.
6.lingual branches(rr. linguales) - terminal branches of the glossopharyngeal nerve: contain sensitive taste fibers to the mucous membrane of the posterior third of the tongue.
X pair - vagus nerves
Nervus vagus(n. vagus), mixed, develops in connection with the fourth or fifth gill arches, is widely distributed due to which it got its name. Innervates the respiratory organs, organs of the digestive system (up to the sigmoid colon), thyroid and parathyroid glands, adrenal glands, kidneys, participates in the innervation of the heart and blood vessels (Fig. 251).
Rice. 251. Nervus vagus:
1 - dorsal nucleus of the vagus nerve; 2 - the core of a single path; 3 - the nucleus of the spinal tract of the trigeminal nerve; 4 - double core; 5 - cranial root of the accessory nerve; 6 - vagus nerve; 7 - jugular opening; 8 - upper node of the vagus nerve; 9 - the lower node of the vagus nerve; 10 - pharyngeal branches of the vagus nerve; 11 - connecting branch of the vagus nerve to the sinus branch of the glossopharyngeal nerve; 12 - pharyngeal plexus; 13 - upper laryngeal nerve; 14 - internal branch of the superior laryngeal nerve; 15 - external branch of the superior laryngeal nerve; 16 - the upper cardiac branch of the vagus nerve; 17 - lower cardiac branch of the vagus nerve; 18 - left recurrent laryngeal nerve; 19 - trachea; 20 - cricoid muscle; 21 - lower constrictor of the pharynx; 22 - middle constrictor of the pharynx; 23 - stylo-pharyngeal muscle; 24 - upper constrictor of the pharynx; 25 - palatopharyngeal muscle; 26 - muscle that raises the palatine curtain, 27 - auditory tube; 28 - ear branch of the vagus nerve; 29 - meningeal branch of the vagus nerve; 30 - glossopharyngeal nerve
The vagus nerve contains sensory, motor and autonomic parasympathetic and sympathetic fibers, as well as small ganglions inside the trunk.
Sensory nerve fibers of the vagus nerve originate from afferent pseudo-unipolar nerve cells, clusters of which form 2 sensory node: upper (ganglion superior), located in the jugular foramen, and lower (ganglion inferior), lying at the exit from the hole. The central processes of cells go to the medulla oblongata to the sensitive nucleus - single path core(nucleus tractus solitary), and peripheral - as part of the nerve to the vessels, heart and viscera, where they end with receptor apparatus.
Motor fibers for the muscles of the soft palate, pharynx and larynx originate from the upper cells of the motor double core.
Parasympathetic fibers originate from the autonomic dorsal nucleus (nucleus dorsalis nervi vagi) and spread as part of the nerve to the muscle of the heart, the muscle tissue of the membranes of the vessels and the viscera. Impulses traveling along the parasympathetic fibers reduce the heart rate, dilate blood vessels, constrict the bronchi, and increase the peristalsis of the tubular organs of the gastrointestinal tract.
Autonomous postganglionic sympathetic fibers enter the vagus nerve along its connecting branches with the sympathetic trunk from the cells of the sympathetic nodes and spread along the branches of the vagus nerve to the heart, blood vessels and viscera.
As noted, the glossopharyngeal and accessory nerves are separated from the vagus nerve during development, so the vagus nerve retains connections with these nerves, as well as with the hypoglossal nerve and the sympathetic trunk through connecting branches.
The vagus nerve emerges from the medulla oblongata behind the olive in numerous roots that merge into a common trunk, which leaves the skull through the jugular foramen. Further, the vagus nerve goes down as part of the cervical neurovascular bundle, between the internal jugular vein and the internal carotid artery, and below the level of the upper edge of the thyroid cartilage - between the same vein and the common carotid artery. Through the upper aperture of the chest, the vagus nerve enters the posterior mediastinum between the subclavian vein and artery on the right and anterior to the aortic arch on the left. Here, by branching and connections between the branches, it forms in front of the esophagus (left nerve) and behind it (right nerve) esophageal nerve plexus (plexus oesophagealis), which near the esophageal opening of the diaphragm forms 2 wandering trunk: front
(tractus vagalis anterior) And back (tractus vagalis posterior), corresponding to the left and right vagus nerves. Both trunks leave the chest cavity through the esophagus, give branches to the stomach and end in a number of terminal branches in celiac plexus. From this plexus, the fibers of the vagus nerve spread along its branches. Throughout the vagus nerve, branches depart from it.
Branches of the head of the vagus nerve.
1.Meningeal branch(r. meningeus) starts from the superior node and through the jugular foramen reaches the dura mater of the posterior cranial fossa.
2.ear branch(r. auricularis) goes from the upper node along the anterolateral surface of the bulb of the jugular vein to the entrance to the mastoid canal and further along it to the posterior wall of the external auditory canal and part of the skin of the auricle. On its way, it forms connecting branches with the glossopharyngeal and facial nerves.
Branches of the cervical vagus nerve.
1.Pharyngeal branches(rr. pharyngeales) originate from the lower node or just below it. They take thin branches from the upper cervical node of the sympathetic trunk and penetrate between the external and internal carotid arteries to the lateral wall of the pharynx, on which, together with the pharyngeal branches of the glossopharyngeal nerve and the sympathetic trunk, they form the pharyngeal plexus.
2.superior laryngeal nerve(n. laryngeus superior) branches off from the lower node and goes down and forward along the side wall of the pharynx medially from the internal carotid artery (Fig. 252). At the greater horn, the hyoid bone is divided into two branches: external (r. externus) And internal (r. internus). The external branch connects with the branches from the superior cervical node of the sympathetic trunk and goes along the posterior edge of the thyroid cartilage to the cricoid muscle and the inferior constrictor of the pharynx, and also gives off branches to the arytenoid and lateral cricoarytenoid muscles inconsistently. In addition, branches depart from it to the mucous membrane of the pharynx and the thyroid gland. The internal branch is thicker, sensitive, pierces the thyroid-hyoid membrane and branches in the mucous membrane of the larynx above the glottis, as well as in the mucous membrane of the epiglottis and the anterior wall of the nasal pharynx. Forms a connecting branch with the lower laryngeal nerve.
3.Superior cervical cardiac branches(rr. cardiaci cervicales superiors) - variable in thickness and branch level, usually thin
cues, originate between the superior and recurrent laryngeal nerves and go down to the cervicothoracic nerve plexus.
4. Inferior cervical cardiac branches(rr. cardiaci cervicales inferiors) depart from the laryngeal recurrent nerve and from the trunk of the vagus nerve; participate in the formation of the cervicothoracic nerve plexus.
Branches of the thoracic vagus nerve.
1. recurrent laryngeal nerve(n. laryngeus recurrents) departs from the vagus nerve as it enters the chest cavity. The right recurrent laryngeal nerve bends around the subclavian artery from below and behind, and the left one - the aortic arch. Both nerves rise in the groove between the esophagus and trachea, giving off branches to these organs. terminal branch - inferior laryngeal nerve (n. laryngeus inferior) approaches the throat
Rice. 252. Laryngeal nerves:
a - right side view: 1 - superior laryngeal nerve; 2 - internal branch; 3 - outer branch; 4 - lower constrictor of the pharynx; 5 - crico-pharyngeal part of the lower constrictor of the pharynx; 6 - recurrent laryngeal nerve;
b - the plate of the thyroid cartilage is removed: 1 - the internal branch of the superior laryngeal nerve; 2 - sensitive branches to the mucous membrane of the larynx; 3 - anterior and posterior branches of the lower laryngeal nerve; 4 - recurrent laryngeal nerve
and innervates all the muscles of the larynx, with the exception of the cricoid, and the mucous membrane of the larynx below the vocal cords.
Branches depart from the recurrent laryngeal nerve to the trachea, esophagus, thyroid and parathyroid glands.
2.Thoracic cardiac branches(rr. cardiaci thoracici) start from the vagus and left laryngeal recurrent nerves; participate in the formation of the cervicothoracic plexus.
3.Tracheal branches go to the thoracic trachea.
4.Bronchial branches go to the bronchi.
5.Esophageal branches approach the thoracic esophagus.
6.Pericardial branches innervate the pericardium.
Within the cavities of the neck and chest, the branches of the wandering, recurrent and sympathetic trunks form the cervicothoracic nerve plexus, which includes organ plexuses: thyroid, tracheal, esophageal, pulmonary, cardiac:
Branches of wandering trunks (abdominal part).
1)anterior gastric branches start from the anterior trunk and form the anterior gastric plexus on the anterior surface of the stomach;
2)posterior gastric branches depart from the posterior trunk and form the posterior gastric plexus;
3)celiac branches depart mainly from the posterior trunk and take part in the formation of the celiac plexus;
4)hepatic branches are part of the hepatic plexus;
5)renal branches form renal plexuses.
XI pair - accessory nerve
accessory nerve(n. accessories) mainly motor, separated in the process of development from the vagus nerve. It begins in two parts - vagus and spinal - from the corresponding motor nuclei in the medulla oblongata and spinal cord. Afferent fibers fit into the trunk through the spinal part from the cells of sensory nodes (Fig. 253).
The wandering part comes out cranial root (radix cranialis) from the medulla oblongata below the exit of the vagus nerve, the spinal part is formed spinal root (radix spinalis), emerging from the spinal cord between the posterior and anterior roots.
The spinal part of the nerve rises to a large hole, enters through it into the cranial cavity, where it connects with the vagus part and forms a common nerve trunk.
In the cranial cavity, the accessory nerve divides into two branches: internal And external.
1. Internal branch(r. internus) approaches the vagus nerve. Through this branch, motor nerve fibers are included in the composition of the vagus nerve, which leave it through the laryngeal nerves. It can be assumed that sensory fibers also pass into the vagus and further into the laryngeal nerve.
Rice. 253. accessory nerve:
1 - double core; 2 - vagus nerve; 3 - cranial root of the accessory nerve; 4 - spinal root of the accessory nerve; 5 - a large hole; 6 - jugular opening; 7 - upper node of the vagus nerve; 8 - accessory nerve; 9 - the lower node of the vagus nerve; 10 - the first spinal nerve;
11 - sternocleidomastoid muscle; 12 - second spinal nerve; 13 - branches of the accessory nerve to the trapezius and sternocleidomastoid muscles; 14 - trapezius muscle
2. outer branch(r. externus) exits the cranial cavity through the jugular foramen to the neck and goes first behind the posterior belly of the digastric muscle, and then from the inside of the sternocleidomastoid muscle. Perforating the last, the external branch goes down and ends in the trapezius muscle. Connections are formed between the accessory and cervical nerves. Innervates the sternocleidomastoid and trapezius muscles.
XII pair - hypoglossal nerve
hypoglossal nerve(n. hypoglossus) predominantly motor, is formed as a result of the fusion of several primary spinal segmental nerves that innervate the hyoid muscles (see Fig. 223).
Nerve fibers that make up the hypoglossal nerve depart from its cells motor nucleus, located in the medulla oblongata (see Fig. 225). The nerve leaves it between the pyramid and the olive with several roots. The formed nerve trunk passes through the canal of the hyoid nerve to the neck, where it is located first between the external (outside) and internal carotid arteries, and then descends under the posterior belly of the digastric muscle in the form of an arc open upwards along the lateral surface of the hyoid-lingual muscle, making up the upper side of the Pirogov triangle (lingual triangle) (Fig. 254, see Fig. 193); branches into terminal lingual branches (rr. linguales), innervating muscles of the tongue.
From the middle of the arc of the nerve down along the common carotid artery goes upper root of the cervical loop (radix superior ansae cervicalis), which connects with her lower spine (radix inferior) from the cervical plexus, resulting in the formation cervical loop (ansa cervicalis). Several branches depart from the cervical loop to the muscles of the neck located below the hyoid bone.
The position of the hypoglossal nerve in the neck can be different. In people with a long neck, the arc formed by the nerve lies relatively low, while in people with a short neck it is high. This is important to consider when operating on a nerve.
Other types of fibers also pass through the hypoglossal nerve. Sensitive nerve fibers come from the cells of the inferior node of the vagus nerve and, possibly, from the cells of the spinal nodes along the connecting branches between the hypoglossal, vagus and
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Rice. 254. Hypoglossal nerve:
1 - hypoglossal nerve in the canal of the same name; 2 - the nucleus of the hypoglossal nerve; 3 - the lower node of the vagus nerve; 4 - anterior branches of the 1st-3rd cervical spinal nerves (form a cervical loop); 5 - upper cervical node of the sympathetic trunk; 6 - upper spine of the neck loop; 7 - internal carotid artery; 8 - lower root of the neck loop; 9 - neck loop; 10 - internal jugular vein; 11 - common carotid artery; 12 - lower belly of the scapular-hyoid muscle; 13 - sternothyroid muscle; 14 - sternohyoid muscle; 15 - upper abdomen of the scapular-hyoid muscle; 16 - shield-hyoid muscle; 17 - hyoid-lingual muscle; 18 - chin-hyoid muscle; 19 - chin-lingual muscle; 20 - own muscles of the tongue; 21 - styloid muscle
cervical nerves. Sympathetic fibers enter the hypoglossal nerve along its connecting branch with the superior node of the sympathetic trunk.
Areas of innervation, fiber composition and names of the cranial nerve nuclei are presented in Table. 15.
Questions for self-control
1. What nerves depart from the vestibular node?
2. What branches of the glossopharyngeal nerve do you know?
3. What branches depart from the head and cervical sections of the vagus nerve? What do they innervate?
4. What branches of the thoracic and abdominal parts of the vagus nerve do you know? What do they innervate?
5. What do the accessory and hypoglossal nerves innervate?
cervical plexus
cervical plexus (plexus cervicalis) is formed by the anterior branches of the 4 upper cervical spinal nerves (C I -C IV), which have interconnections. The plexus lies on the side of the transverse processes between the vertebral (back) and prevertebral (front) muscles (Fig. 255). The nerves emerge from under the posterior edge of the sternocleidomastoid muscle, slightly above its middle, and fan out upward, forward, and downward. The following nerves depart from the plexus:
1.Lesser occipital nerve(n. occipitalis mino)(from C I -C II) extends upward to the mastoid process and further to the lateral sections of the occiput, where it innervates the skin.
2.Great ear nerve(n. auricularis major)(from C III -C IV) goes up and anteriorly along the sternocleidomastoid muscle to the auricle, innervates the skin of the auricle (posterior branch) and the skin above the parotid salivary gland (anterior branch).
3.Transverse nerve of the neck(n. transverse colli)(from C III -C IV) goes anteriorly and at the anterior edge of the sternocleidomastoid muscle is divided into upper and lower branches that innervate the skin of the anterior neck.
4.Supraclavicular nerves(nn. supraclavicularis)(From C III -C IV) (numbering 3 to 5) spread downward in a fan-like fashion under the subcutaneous muscle of the neck; branch in the skin of the back of the neck (lateral
Table 15 Areas of innervation, fiber composition and names of cranial nerve nuclei
Continuation of the table. 15
The end of the table. 15
Rice. 255. cervical plexus:
1 - hypoglossal nerve; 2 - accessory nerve; 3, 14 - sternocleidomastoid muscle; 4 - large ear nerve; 5 - small occipital nerve; 6 - large occipital nerve; nerves to the anterior and lateral rectus muscles of the head; 8 - nerves to the long muscles of the head and neck; 9 - trapezius muscle; 10 - connecting branch to the brachial plexus; 11 - phrenic nerve; 12 - supraclavicular nerves; 13 - lower belly of the scapular-hyoid muscle; 15 - neck loop; 16 - sternohyoid muscle; 17 - sternothyroid muscle; 18 - upper abdomen of the scapular-hyoid muscle; 19 - transverse nerve of the neck; 20 - lower root of the neck loop; 21 - upper spine of the neck loop; 22 - thyroid muscle; 23 - geniohyoid muscle
branches), in the region of the clavicle (intermediate branches) and the upper anterior part of the chest up to the III rib (medial branches).
5. Phrenic nerve(n. phrenicis)(from C III -C IV and partly from C V), predominantly a motor nerve, goes down the anterior scalene muscle into the chest cavity, where it passes to the diaphragm in front of the lung root between the mediastinal pleura and the pericardium. Innervates the diaphragm, gives sensitive branches to the pleura and pericardium (rr. pericardiaci), sometimes to the cervicothoracic neuro-
mu plexus. In addition, it sends diaphragmatic-abdominal branches (rr. phrenicoabdominales) to the peritoneum covering the diaphragm. These branches contain nerve nodes (ganglia phrenici) and connect with the celiac nerve plexus. Especially often, the right phrenic nerve has such connections, which explains the phrenicus symptom - irradiation of pain in the neck with liver disease.
6.Lower spine of the neck loop(radix inferior ansae cervicalis) formed by nerve fibers from the anterior branches of the second and third spinal nerves and goes anteriorly to connect with top spine (radix superior), arising from the hypoglossal nerve (XII pair of cranial nerves). As a result of the connection of both roots, a neck loop is formed. (ansa cervicalis), from which branches depart to the scapular-hyoid, sternohyoid, thyroid-hyoid and sternothyroid muscles.
7.Muscular branches(rr. musculares) go to the prevertebral muscles of the neck, to the muscle that lifts the scapula, as well as to the sternocleidomastoid and trapezius muscles.
Cervical sympathetic trunk lies in front of the transverse processes of the cervical vertebrae on the surface of the deep muscles of the neck (Fig. 256). In each cervical region there are 3 cervical nodes: top, middle (ganglia cervicales superior et media) And cervicothoracic (stellate ) (ganglion cervicothoracicum (stellatum)). The middle cervical node is the smallest. The stellate node often consists of several nodes. The total number of nodes in the cervical region can vary from 2 to 6. Nerves depart from the cervical nodes to the head, neck and chest.
1.gray connecting branches(rr. communicantens grisei)- to the cervical and brachial plexuses.
2.Internal carotid nerve(n. caroticus internus) usually departs from the upper and middle cervical nodes to the internal carotid artery and forms around it internal carotid plexus (plexus caroticus internus), which extends to its branches. Branches from the plexus deep stony nerve (n. petrosus profundus) to the pterygoid node.
3.jugular nerve(n. jugularis) starts from the upper cervical node, within the jugular opening is divided into two branches: one goes to the upper node of the vagus nerve, the other - to the lower node of the glossopharyngeal nerve.
Rice. 256. Cervical department of sympathetic trunk:
1 - glossopharyngeal nerve; 2 - pharyngeal plexus; 3 - pharyngeal branches of the vagus nerve; 4 - external carotid artery and nerve plexus; 5 - upper laryngeal nerve; 6 - internal carotid artery and sinus branch of the glossopharyngeal nerve; 7 - sleepy glomus; 8 - sleepy sinus; 9 - upper cervical cardiac branch of the vagus nerve; 10 - upper cervical cardiac nerve;
11 - middle cervical node of the sympathetic trunk; 12 - middle cervical cardiac nerve; 13 - vertebral node; 14 - recurrent laryngeal nerve; 15 - cervicothoracic (star-shaped) node; 16 - subclavian loop; 17 - vagus nerve; 18 - lower cervical cardiac nerve; 19 - thoracic cardiac sympathetic nerves and branches of the vagus nerve; 20 - subclavian artery; 21 - gray connecting branches; 22 - upper cervical node of the sympathetic trunk; 23 - vagus nerve
4.Vertebral nerve(n. vertebralis) departs from the cervicothoracic node to the vertebral artery, around which it forms vertebral plexus(plexus vertebralis).
5.Cardiac cervical superior, middle and inferior nerves(nn. cardiaci cervicales superior, medius et inferior) originate from the corresponding cervical nodes and are part of the cervicothoracic nerve plexus.
6.External carotid nerves(nn. carotici externi) depart from the upper and middle cervical nodes to the external carotid artery, where they participate in the formation external carotid plexus (plexus caroticus externus), which extends to the branches of the artery.
7.Laryngo-pharyngeal branches(rr. laryngopharyngei) go from the superior cervical ganglion to the pharyngeal plexus and as a connecting branch to the superior laryngeal nerve.
8.Subclavian branches(rr. subclavii) move away from subclavian loop (ansa subclavia), which is formed by the division of the internodal branch between the middle cervical and cervicothoracic nodes.
Cranial division of the parasympathetic nervous system
Centers cranial department The parasympathetic part of the autonomic nervous system is represented by nuclei in the brainstem (mesencephalic and bulbar nuclei).
Mesencephalic parasympathetic nucleus - accessory nucleus of the oculomotor nerve (nucleus accessories n. oculomotorii)- located at the bottom of the aqueduct of the midbrain, medial to the motor nucleus of the oculomotor nerve. Preganglionic parasympathetic fibers run from this nucleus as part of the oculomotor nerve to the ciliary ganglion.
The following parasympathetic nuclei lie in the medulla oblongata and pons:
1)superior salivary nucleus(nucleus salivatorius superior), associated with the facial nerve - in the bridge;
2)inferior salivary nucleus(nucleus salivatorius inferior), associated with the glossopharyngeal nerve - in the medulla oblongata;
3)dorsal nucleus of the vagus nerve(nucleus dorsalis nervi vagi),- in the medulla oblongata.
Preganglionic parasympathetic fibers pass from the cells of the salivary nuclei as part of the facial and glossopharyngeal nerves to the submandibular, sublingual, pterygopalatine and ear nodes.
Peripheral department parasympathetic nervous system is formed by preganglionic nerve fibers, occurring
from the indicated cranial nuclei (they pass as part of the corresponding nerves: III, VII, IX, X pairs), the nodes listed above and their branches containing postganglionic nerve fibers.
1. Preganglionic nerve fibers, which go as part of the oculomotor nerve, follow to the ciliary node and end on its cells with synapses. Depart from the node short ciliary nerves (nn. ciliares breves), in which, along with sensory fibers, there are parasympathetic: they innervate the sphincter of the pupil and the ciliary muscle.
2. Preganglionic fibers from the cells of the superior salivary nucleus spread as part of the intermediate nerve, from it through the large stony nerve they go to the pterygopalatine node, and through the tympanic string to the submandibular and hyoid nodes, where they end in synapses. From these nodes, along their branches, postganglionic fibers follow to the working organs (submandibular and sublingual salivary glands, glands of the palate, nose and tongue).
3. Preganglionic fibers from the cells of the lower salivary nucleus go as part of the glossopharyngeal nerve and further along the small stony nerve to the ear node, on the cells of which they end in synapses. Postganglionic fibers from the cells of the ear node exit as part of the ear-temporal nerve and innervate the parotid gland.
Preganglionic parasympathetic fibers, starting from the cells of the dorsal node of the vagus nerve, pass as part of the vagus nerve, which is the main conductor of parasympathetic fibers. Switching to postganglionic fibers occurs mainly in the small ganglia of the intramural nerve plexuses of most internal organs, so postganglionic parasympathetic fibers appear to be very short compared to preganglionic ones.
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Cranial nerve injuries (CNI) are often the main cause of disability in patients who have suffered a traumatic brain injury. In many cases, PCF occurs with mild and moderate trauma to the skull and brain, sometimes against the background of preserved consciousness (at the time of injury and after it). The significance of PCN can be different: if damage to the olfactory nerves leads to a decrease or absence of smell, then patients may not notice or ignore this defect. At the same time, damage to the optic or facial nerve can lead to severe disability and social exclusion of patients due to visual impairment or the appearance of a gross cosmetic defect.
It has been noted that direct damage to the intracranial segments of the CN by the type of neurot-mesis (rupture) or neuropraxia (intraneural destruction) is very rare, due to the fact that the length of the intracranial segments is several millimeters longer than the distance between the points of exit from the brain stem and from the cranial cavity, as well as due to the shock-absorbing properties of the cerebrospinal fluid contained in the basal cisterns.
In TBI, damage to the cranial nerves in most cases is due to their compression in the bone canals (I, II, VII, VIII nn), either due to compression by their edematous brain or intracranial hematoma (III n), or in the wall of the cavernous sinus in traumatic carotid-cavernous fistulas (III, IV, VI, the first branch of V).
Special mechanisms of damage to the cranial nerves inherent in wounds by foreign bodies and gunshot wounds.
According to the literature, more often with TBI suffer V (from 19 to 26 %) and VII nerves (from 18 to 23%), less often III nerve (from 9 to 12%), XII nerve (from 8 to 14%),
VI nerve (from 7 to 11%), IX nerve (from 6 to K)%). We point out that damage to a number of cranial nerves is considered in the chapters devoted to the neuro-ophthalmological and otoneurological consequences of TBI.
DAMAGEtrigeminal nerve
Anatomy
The trigeminal nerve has three main branches. I branch - ophthalmic nerve - innervates the skin of the forehead, temporal and parietal regions, upper eyelid, back of the nose, nasal mucosa and its paranasal sinuses, the membrane of the eyeball and the lacrimal gland. As it moves away from the Gasser node, the nerve passes through the thickness of the outer wall of the cavernous sinus and through the superior orbital fissure enters the orbit.
II branch - the maxillary nerve - innervates the dura mater of the brain, the skin of the lower eyelid, the outer canthus of the eye, the anterior part of the temporal region, the upper part of the cheek, the wings of the nose, the skin and mucous membrane of the upper lip, the mucous membrane of the maxillary sinus, palate, teeth of the upper jaw . The maxillary nerve exits the cranial cavity through a round opening into the pterygopalatine fossa. The infraorbital nerve, which is a continuation of the II branch, passes in the infraorbital groove, leaving the face through the infraorbital foramen.
III branch - mandibular nerve - innervates the dura mater, skin of the lower lip, chin, lower cheek, anterior part of the auricle and anterior auditory canal, tympanic membrane, buccal mucosa, floor of the mouth and anterior 2/3 of the tongue, teeth of the lower jaw, chewing muscles and muscles of the palatine curtain. It exits the cranial cavity through the foramen ovale into the infratemporal fossa and forms a series of branches.
Mechanisms of damage
Injuries to the gasser node and trigeminal nerve roots occur with fractures of the base of the skull. Damage to the temporal bone, passing to the openings of the sphenoid bone, the base of the middle cranial fossa, can cause compression or rupture of the branches of the trigeminal nerve. Direct damage to the soft tissues of the face, dislocation of orbital structures, trauma to the upper and lower jaws can also damage the trigeminal nerve.
Clinic and diagnostics
When the gasser node is damaged, dull, periodically aggravated pains occur in the zone of innervation of all branches of the trigeminal nerve, sensitivity disorders and herpetic eruptions are observed, as well as neurotrophic complications (keratitis, conjunctivitis). When the branches of the V nerve are damaged, pain syndromes of varying severity manifest, localized in the zones of their innervation. Recognition of damage to the trigeminal nerve is based on characteristic signs - hypesthesia or hyperpathy in the areas of its innervation, disorders of chewing and movements of the lower jaw, irritation or inhibition of corneal and other reflexes realized through the Vth nerve, as well as autonomic disorders.
Treatment
In post-traumatic trigeminal pain syndromes, a complex of analgesic, absorbable, vascular, metabolic therapy is used.
The priority indication for surgery is damage to the I branch of the trigeminal nerve, leading to neuroparalytic keratitis, with the formation of corneal ulcers. Retroganglionic damage to the I branch of the trigeminal nerve can be treated by combined trigeminal nerve plasty with an autograft from the lower leg connected to the greater occipital nerve. The operation consists of a frontolateral epidural approach with an approach to the roof of the orbit, opening it and isolating the ophthalmic nerve.
Autograft n.suralis is sutured with one end to the ophthalmic branch, the other - to the great occipital nerve. Restoration of sensitivity is possible after 6 months.
The indication for the reconstruction of the inferior alveolar nerve is anesthesia in the region of the lower lip, its dysfunction and possible trauma. The operation is performed by neurosurgeons together with maxillofacial surgeons. The distal and proximal ends of the nerve are isolated in the mandible and mental foramen, identified, marked, followed by nerve suture, if necessary, using an autograft.
DAMAGE TO THE FACIAL NERVE
One of the serious complications arising from traumatic brain injury is peripheral paralysis of the facial nerve. In terms of frequency of occurrence, traumatic injuries of the facial nerve are in second place after idiopathic Bell's palsy. In the structure of traumatic brain injury, damage to the facial nerve is observed in 7-53% of patients with fractures of the base of the skull.
Injuries to the facial nerve resulting from a fracture of the base of the skull are divided into early and late. Paresis and paralysis arising immediately after the injury, indicating direct nerve damage, as a rule, have an unfavorable outcome. Peripheral paresis of the facial nerve may also occur later after injury, most often after 12-14 days. These paresis are caused by secondary compression, edema, or hematoma in the nerve sheath. In these cases, the continuity of the nerve is preserved.
Mechanisms of damage
Longitudinal fractures of the temporal bone account for over 80% of all fractures of the temporal bone. More often occur with side, oblique blows to the head. The fracture line runs parallel to the axis of the pyramid and often, bypassing the labyrinth capsule, deviates to the sides, splitting the tympanic cavity, displacing the hammer and anvil, which leads to fractures and dislocation of the stirrup. As a rule, otorrhea occurs on the side of the lesion, the eardrum is injured.
Damage to the 7th nerve in longitudinal fractures occurs in 10-20% of all injuries, in most cases in the near-knee zone, in the bone canal of the temporal bone. They rarely cause a complete rupture of the nerve trunk, and have a favorable prognosis.
Transverse fractures occur in 10-20% of cases. The mechanism of the fracture is a blow to the head in the anterior-posterior direction. The fracture line runs from the tympanic cavity through the wall of the facial nerve canal in its horizontal segment to the internal auditory meatus through the vestibule of the labyrinth. Transverse fractures are also divided into external and internal, depending on the communication of the fracture with the external auditory canal. Hearing loss occurs in the form of sensory hearing loss. The tympanic membrane may remain intact, which does not exclude the possibility of the formation of a hematotympanum on the side of the lesion. The occurrence of rhinorrhea with these fractures is explained by the penetration of cerebrospinal fluid from the middle ear through the Eustachian tube into the nasal cavity. In 50% loss of vestibular function is possible. Damage to the facial nerve in transverse fractures is much grosser and occurs much more frequently than in longitudinal fractures. .
With gunshot wounds, the nerve is damaged in 50% of cases. The nerve can be crossed by a wounding projectile (bullet, fragment) damaged secondarily by the kinetic energy of the bullet. Bullet wounds are more severe than shrapnel, because. the bullet is much larger than the fragments in mass and, flying at a higher speed, gives more severe damage. Most often, with a gunshot wound, the mastoid process, the exit site of the nerve from the awl-mastoid opening, and the tympanic membrane are damaged.
pathohistology
With traumatic injuries of the facial nerve, various biochemical and histological changes occur not only distally, but also in the proximal portion of the nerve. At the same time, in addition to the nature of the injury (intersection during surgery, traumatic compression), the severity of the clinical manifestation of damage depends on the proximity to its nucleus of the facial nerve - the closer to the latter, the more severe and pronounced the degree of damage to the nerve trunk.
A pathohistological classification has been proposed to assess the degree of damage to the facial nerve (Sunderland S.):
1 degree - neuropraxia - block of impulse conduction, with compression of the nerve trunk. At the same time, the integrity of the nerve and its elements are preserved.
(endo-periepineurium). Valerian regeneration is not observed in this case. When the pressure is removed, the function of the nerve is restored completely in a relatively short time.
Grade 2 - axonotmesis - parietal tear of the axon with the outflow of axoplasmic fluid. This creates a Valerian degener
tion, expressed distal to the site of damage to the nerve trunk. The nerve sheath is preserved, and the connective tissue elements remain intact. The nerve retains the ability to regenerate (at a rate of 1 mm per day) distally, potentially facilitating recovery.
Grade 3 - endoneurotmesis - the endoneurium and axon are damaged, parietal degeneration occurs, but the perineurium remains intact. Valerian degeneration is distal and proximal to the damage for some extent in both directions. Axons in this case can regenerate, but complete recovery is impossible due to the cicatricial adhesive process that develops at the site of damage and interferes with the advancement of the fibers. This leads to partial reinnervation of the nerve trunk. In addition, the directed growth of the axon changes, leading to synkinesis and incomplete restoration of nerve functions.
Grade 4 - perineuromesis. Only the epineurium remains intact, while the axon, endo-, and perineurium are destroyed. Severe Valerian degeneration. This is an aberrant form of regeneration, as there is no chance for restoration of nerve functions, without surgical comparison.
Grade 5 - epineurotmesis. Complete damage to all elements of the nerve trunk, the occurrence of neuromas. Recovery, even partial, in
this stage does not occur. The surgical solution of the problem also does not lead to the desired results.
Clinic
The clinical picture of damage to the facial nerve is well known and depends on the level of damage and the degree of conduction disturbance. The leading symptom of damage to the facial nerve is peripheral paresis or paralysis of the mimic muscles of the corresponding half of the face.
Facial nerve syndrome (syn.: Bell's syndrome) includes paralysis of all facial muscles of the homolateral half of the face (lack of the possibility of wrinkling the forehead and frowning, lack of closure of the palpebral fissure, smoothness of the nasolabial fold, lowering of the corner of the mouth, impossibility of baring teeth and puffing out the cheeks, masking of the affected half of the face) and is often accompanied by a taste disorder in the anterior 2/3 of the half of the tongue of the same name, hyperracusia (unpleasant, increased perception of sound), impaired lacrimation (hyper- or alacrimania), and dry eyes.
There are 3 segments of the facial nerve: intracranial, which includes a segment from the exit point of the nerve from the brain stem to the internal auditory canal, intrapyramidal from the internal auditory canal to the stylomastoid foramen, and extracranial. Features of the topographic anatomy of the facial nerve, due to its location in close proximity to the brain stem, cochleovestibular nerve, structures of the inner and middle ear, parotid salivary gland, determine both the high frequency of its lesions and the difficulties of surgical treatment.
Depending on the level of damage, Bell's syndrome has several topical variants (Fig. 12-1).
With damage to the facial nerve root emerging from the brain stem in the lateral cistern of the bridge (ponto-cerebellar angle) along with the V, VI and VIII cranial nerves of its half, the clinical picture of the syndrome will include symptoms of dysfunction of these nerves. Pain and disturbances of all types of sensitivity in the area of innervation of the branches of the trigeminal nerve are noted, sometimes combined with damage to the homolateral masticatory muscles (damage to the Vth nerve), peripheral paralysis of the facial nerve, hearing loss, noise and vestibular disorders (damage to the VIII nerve), sometimes combined with cerebellar symptoms Is that on this side:
Topical variants of the seventh nerve syndrome when it is damaged in the fallopian canal depend on the level of the lesion:
With damage to the discharge of n. petrosus major, in which all accompanying fibers are involved in the process, in the clinical picture, in addition to peripheral paralysis of the mimic muscles, there is dryness of the eye (damage to n. petrosus), hyperacusis (damage to n. stapedius), a violation of taste in the anterior 2/3 of the tongue (lesion of chordae tympani);
Rice. 12-1. Levels of damage to the facial nerve and their recognition.
With a lower localization of the lesion above the place of origin of n. stapedius, in addition to peripheral paralysis of the mimic muscles of the same half of the face, hyperacusis is observed, a violation of taste in the anterior 2/3 of the tongue of the same half of the latter. Dryness of the eye is replaced by increased lacrimation;
With a lesion above the discharge of the chordae tympani, lacrimation and a violation of taste in the anterior 2/3 of the tongue are noted;
With a lesion below the discharge of the chordae tympani or at the exit from the stylomastoid opening, paralysis of all the facial muscles of its half occurs, combined with lacrimation.
The most common lesion of the VII nerve occurs at the exit from the facial canal and after exit from the skull.
With a total lesion of the facial nerve (the nucleus and trunk of the facial nerve), peripheral paralysis of all facial muscles occurs - the affected side is mask-like, there are no nasolabial and frontal folds. The face is asymmetrical - the tone of the muscles of the healthy half of the face "pulls" the mouth to the healthy side. The eye is open (lesion of m. orbicularis oris) - lagophthalmos - "hare's eye". When you try to close the eye, the eyeball shifts upward, the iris goes under the upper eyelid, there is no closure of the palpebral fissure (Bell's symptom). With incomplete damage to the orbicular muscle of the eye, the palpebral fissure closes, but less tightly than on the healthy side, and eyelashes often remain visible (eyelash symptom). With lagophthalmos, lacrimation is often observed (if the normal function of the lacrimal glands is preserved). Due to the defeat of m. orbicularis oris, whistling is impossible, speech is somewhat difficult. On the affected side, liquid food spills out of the mouth. In the future, atrophy of isolated muscles develops and the reaction of degeneration corresponding to it and changes in EMG of a peripheral nature are observed. There are no superciliary, corneal and conjunctival reflexes (damage to the efferent part of the corresponding reflex arc).
Diagnostics
Along with the described neurological symptoms, when recognizing damage to the facial nerve, various tests and techniques are used.
Schirmer test includes the identification of dysfunction of the superficial petrosal nerve through the study of lacrimation. Two strips of filter paper, 7 cm long and 1 cm wide, are inserted into the conjunctival sac for two minutes, and the area of soaking of the strips with tears is determined, in millimeters. After 3-5 minutes, the length of the wetted area of the paper is compared. A 25% reduction in the length of the wetted area is considered to be a manifestation of damage at this level. Damage proximal to the geniculate node can lead to the development of keratitis.
Stapedius reflex designed to test a branch of the facial nerve, the stapedial nerve, which leaves the main nerve trunk just after the second genu in the mastoid process. Of all the tests - the most correct. Examine using standard audiograms. This test is important only in case of trauma; in case of infectious lesions of the nerve, it is not informative.
The study of taste sensitivity, by applying various paper taste tests to the anterior 2/3 of the tongue, reveals lesions at the chorda tympani level. But this test is not entirely objective. More correct, in this case, is to study under a microscope the reaction of the papillae of the tongue to various taste tests in the form of a change in the shape of the papillae. But during the first 10 days after the injury, the papillae do not respond to the taste stimulus. Lately the taste is explored electrometrically (electrogustometry), determining the threshold sensations of an electric current, causing a specific sour taste when the tongue is irritated.
Salivation test - damage to the facial nerve at the level of the tympanic string is also detected. The Wharton duct is cannulated from 2 sides, and salivation is measured for 5 minutes. Also not very convenient, and not quite an objective test.
Electrophysiological tests are the most informative studies in patients with complete facial nerve palsies both for prognosis and study of the dynamics of axon growth, as well as for deciding on nerve surgery - whether to decompress the nerve or not.
Tests for excitability, for maximum stimulation, electroneuronography. They give the most correct results within the first 72 hours after a nerve injury. After 3-4 days, due to the increase in the degree of nerve degeneration, these research methods become therapeutic (nerve regeneration is accelerated).
Excitability test - stimulating electrodes are located in the stylomastoid foramen on both sides, to which electrical discharges are applied. Further, the indicators are compared with each other, and, depending on the results obtained, they build a prognosis in terms of restoring nerve function. Quite a cheap test, but with a large number of errors.
Maximum stimulation of the branches of the facial nerve is a modified version of the first test. The mechanism is the depolarization of all facies branches. The test starts from the 3rd day after the injury, and is repeated periodically.
Electroneprography is an objective test that consists in the qualitative study of nerve degeneration by stimulating the nerve in the stylomastoid foramen with direct current pulses. The response to stimuli is recorded using bipolar electrodes attached near the nasolabial fold. The number of evoked potentials is equal to the number of intact axons, and the intact side, in percentage terms, is compared with the damaged one. The detection of evoked potentials in less than 10% indicates a poor prognosis for spontaneous recovery. The disadvantage of this test is discomfort for the patient, the difficult position of the electrodes, and the high cost of the study.
Electromyography using 2x and 3x phase potentials, through needle transcutaneous electrodes installed in the facial muscles, records the potentials from the latter, revealing the electrical conductivity of the facial nerve. The method is of limited value, because up to 2 weeks after injury, due to the resulting fibrillations of the facial muscles (caused by neuronal degeneration), it is not possible to obtain true results. But it becomes important after 2 weeks, due to the reinnervation of axons into muscles. Registration of polyphasic potentials indicates the beginning of reinnervation.
Examination algorithm for traumatic injury of the facial nerve: anamnesis, primary examination, neurological examination (including examination of all nerves), otoscopy, Weber test, Rinne test, audiometry (clear sound and speech), stapedius reflex, Schirmer test, electrogustometry, electroneuro and electromyography, X-ray of the skull (survey and in laying according to Schüller, Mayer, Stanvers, CT-MRI of the brain, angiography (with penetrating wounds of the temporal bone, gunshot bullet wounds).
Treatment
Surgery
Methods of surgical interventions for persistent syndromes of complete violation of the conduction of the facial nerve can be divided into two groups:
1. Surgical interventions on the facial nerve in order to restore its conduction and voluntary motor function of facial muscles (decompression operations).
2. Plastic surgery on the skin, muscles and tendons of the face in order to reduce the cosmetic defect and replace the function of paralyzed muscles.
In case of fractures of the temporal bone, decompression of the nerve at the site of compression is carried out - removal of the bone, evacuation of the hematoma; if a nerve break is detected, the perineural sheath should be sutured with at least three sutures around the circumference with preliminary refreshment of the ends of the nerve at a right angle. On the other hand, clinical experience shows that without surgery, nerve function can recover to some extent in 2/3 of the victims. Kamerer D.B., Kazanijian V.H. and others recommend decompression as early as possible in all cases of paralysis (within the first 24-48 hours). Most experts consider the optimal period for surgical treatment of severe injuries of the VII nerve to be from 4 to 8 weeks after the injury, since the results of operations after 8-10 weeks. from the development of paralysis are ineffective. Fisch U. considers it appropriate to intervene on the 7th day from the onset of paralysis of VII n. over time, it is possible to reveal the dynamics of the process. CT, MRI, electrodiagnostics are necessary for the timely decision to perform surgery in case of injury to the VII nerve.
The facial nerve was the first nerve to undergo reinnervation (neuroplasty, nerve anastomosis), which consisted in suturing the peripheral segment of the facial nerve with the central segment of another, specially crossed, motor nerve. For the first time in the clinic, reinnervation of the facial nerve by the accessory nerve was performed by Drobnik in 1879, and by the hypoglossal nerve by Korte in 1902. Soon these operations began to be used by many surgeons. As donor nerves for the reinnervation of the facial nerve, in addition to the accessory and hypoglossal nerves, the glossopharyngeal nerve, the phrenic nerve, and the descending branch of the hypoglossal nerve were used; II and III cervical nerves, muscular branch of the accessory nerve to the sternocleidomastoid muscle. To date, considerable experience has been accumulated in operations of extracranial reinnervation of the facial nerve.
Reinnervation of the facial nerve by the accessory nerve: the main effect of the operation is to prevent muscle atrophy and restore their tone.
Hyoid nerve reinnervation of the facial nerve is the most commonly used technique for extracranial facial nerve reinnervation. Many authors, giving preference to this technique, emphasize that there are functional relationships between the motor areas of the face and tongue in the central nervous system.
Reinnervation of the facial nerve by the hypoglossal nerve with simultaneous reinnervation of the hypoglossal nerve by its descending branch is the most commonly used operation for injuries of the facial nerve.
Reinnervation of the facial nerve by the phrenic nerve. The intersection of the phrenic nerve is usually not accompanied by serious neurological disorders. Restoration of the function of mimic muscles after reinnevation of the facial nerve by the phrenic nerve is accompanied by pronounced friendly movements, synchronous with breathing, the elimination of which requires long-term conservative treatment.
Reinnervation of the facial nerve by the anterior branch of the 2nd cervical nerve, the glossopharyngeal nerve, has not been widely used in clinical practice.
Methods of extracranial reinnervation of the facial nerve, being technically simple and less traumatic, ensure the restoration of the function of facial muscles, however, they have a number of serious drawbacks. The crossing of the donor nerve entails additional neurological disorders, the restoration of the function of facial muscles is accompanied by friendly movements, which are not always successfully relearned. These shortcomings significantly reduce the effectiveness of operations, and the results are not fully satisfactory for patients and surgeons.
Cross autoplasty of the facial nerve (cross-face anastomose, cross-face nerve grafting). The first publications on L.Scaramella cross transplantation, J.W.Smith, H.Andrel. The essence of the operation is the reinnervation of the affected facial nerve or its branches with separate branches of a healthy facial nerve through autografts, which makes it possible to create connections between the corresponding branches of the facial nerves. Usually three autografts are used (one for the muscles of the eye and two for the muscles of the cheek and circumference of the mouth). The operation can be performed in one or (more often) in two steps. Early dates are preferred. Surgical technique is of great importance.
To improve the results, facial plastic surgery is also used, which can be divided into static and dynamic. Static operations are aimed at reducing facial asymmetry - tarsorrhaphy to reduce lagophthalmos, tightening of the facial skin.
Methods of multi-directional suspensions have been proposed to eliminate eyebrow overhangs, lagophthalmos, and pubescence of the cheek and corner of the mouth. For this, fascial bands are used, cut from the wide fascia of the thigh. Even cases of implantation of a metal spring in the upper eyelid are described. However, the authors themselves note that a rejection reaction may develop. In the absence of good fixation, the spring can be pushed out, even with perforation of the skin. A similar complication also occurs when magnets are implanted into the eyelids (rejection reaction in 15% of cases).
Plastic surgery aims to replace the function of paralyzed muscles. In 1971, a free muscle-tendon autograft was transplanted for the first time. This operation was undertaken by many surgeons. The authors note that transplanted muscles often undergo cicatricial degeneration. With the development of microsurgical techniques, muscle transplantation with microvascular and nerve anastomosis and the transfer of muscle flaps from the temporalis muscle, masseter muscle, and subcutaneous muscle of the neck began to be more widely used. The following indications for the use of plastic surgery have been formulated:
1. To improve the results after surgical interventions on the facial nerve.
2. In the later stages after damage to the facial nerve (4 or more years).
3. After extensive damage to the face, when intervention on the facial nerve is not possible.
Conservative treatment
Treatment of lesions of the facial nerve should be comprehensive. Conservative treatment should be carried out from the first week. Schemes of conservative treatment and methods of phased exercise therapy have been developed to eliminate friendly movements of the mimic muscles for patients who underwent reinnervation of the facial nerve.
Physiotherapy exercises in the surgical treatment of facial nerve injuries can be divided into three distinct periods: preoperative, early postoperative, late postoperative.
In the preoperative period, the main task is to actively prevent asymmetries of the healthy and diseased sides of the face. The sharp asymmetry of the face, which was created on the first day after the main operation, requires immediate and strictly directed correction. Such a correction is achieved by two methodological methods: positional treatment with the help of adhesive plaster tension and special gymnastics for the muscles of the healthy half of the face.
The adhesive plaster tension is carried out in such a way that the adhesive plaster is applied to the active points of the healthy side of the linden - the area of the square muscle of the upper lip, the circular muscle of the mouth (on the healthy side) and with a sufficiently strong tension directed towards the diseased side, is attached to a special helmet-mask or postoperative bandage, to its side straps. Such tension is carried out during the day from 2 to 6 hours a day with a gradual increase in the time of treatment with the position. Such a bandage is especially important during active facial actions: eating, speech articulation, emotional situations, because the weakening of the asymmetric traction of the muscles of the healthy side improves the overall functional position of the paralyzed muscles, which plays a huge role in the postoperative period, especially after the germination of the sutured nerve.
Separately, treatment is considered with the position for the circular muscle of the eye on the affected side. Here, a crow's foot adhesive plaster is applied to the middle of the upper and lower eyelids and stretched outwards and slightly upwards. At the same time, the palpebral fissure narrows significantly, which ensures almost complete closure of the upper and lower eyelids when blinking, normalizes tear secretion, and protects the cornea from drying out and ulceration. During sleep, the main adhesive plaster tension is removed, and may remain in the eye area.
Special gymnastics in this period is also mainly aimed at the muscles of the healthy side - training is provided for active muscle relaxation, dosed and, of course, differentiated tension of the main facial muscle groups - the zygomatic, circular muscles of the mouth and eye, triangular muscle. Such exercises with the muscles of the healthy half also improve the symmetry of the face, prepare these muscles for such a dosed tension, which in subsequent periods will be the most adequate, functionally beneficial, slowly recovering paretic muscles.
The second period, early postoperative - from the moment of plastic surgery to the first signs of nerve germination. In this period, basically, the same rehabilitation measures continue as in the first period: treatment with position and special gymnastics, aimed mainly at dosed training of the muscles of the healthy side of the face. Additional to the previous exercises is the need for reflex exercises - static tension of the muscles of the tongue and forced swallowing training.
Tension of the tongue is achieved as follows: the patient is instructed to "rest" with the tip of the tongue against the line of closed teeth (2-3 seconds of tension), then relax and again "rest" against the gum - now above the teeth. After relaxation - focus on the gum below the teeth. Similar series of tensions (emphasis in the middle, up, down) are done 3-4 times a day, 5-8 times during each series.
Swallowing is also carried out in series, 3-4 sips in a row. Ordinary swallowing can be combined with liquid pouring, especially if the patient complains of dry mouth. Combined movements are also possible - static tension of the tongue and, at the same time, swallowing. After such a combined exercise, a longer rest (3-4 minutes) is needed than after individual exercises. During this period, various types of restorative treatment can be recommended - vitamin therapy, massage of the collar zone, etc. A course of dibazol is recommended for 2 months. Massage of the face, especially the affected side, in this period is considered inappropriate.
The third, late postoperative period begins from the moment of the first clinical manifestations of nerve ingrowth. Before others, the movement of the muscles of laughter and one of the portions of the zygomatic muscle appears. In this period, the main emphasis is on therapeutic exercises. Static exercises for the muscles of the tongue and swallowing continue, however, the number of exercises is significantly increased - 5-6 times a day and the duration of these exercises. Before and after classes, massage of the affected half of the face is recommended.
Especially valuable is the massage from the inside of the mouth, when the exercise therapy instructor massages (with a hand in a surgical glove) individual (if possible) muscle groups - the square muscle of the upper lip, the zygomatic, circular muscle of the mouth, the cheek muscle.
As the amplitude of voluntary movements increases, exercises are added in symmetrical tension on both sides - healthy and affected. Here, an important methodological principle is the need to equate the strength and amplitude of muscle contraction of the healthy side to the limited capabilities of the muscles of the affected side, but not vice versa, because the tertiary muscles, even with maximum contraction, cannot equalize with healthy muscles, and, thereby, provide facial symmetry. Only equating healthy muscles to paretic ones eliminates the asymmetry and thus increases the overall effect of surgical treatment.
The movements of the circular muscle of the eye appear much later and are at first synergistic with contractions of the muscles of the lower and middle parts of the face. This synergy should be strengthened in every possible way for two to three months (by joint contractions of all the muscles of the affected side), and after reaching a sufficient amplitude of contraction of the circular muscle of the eye, it is necessary to achieve a differentiated separation of these contractions. This is achieved by a certain function of the muscles and the transfer of the skill of separate contraction of the muscles of the healthy side (see the first period) to the affected side. In the same period, it is recommended to carry out treatment with the position according to a known method, however, the time is reduced to 2-3 hours every other day.
Apply medical treatment; recovery course: gliatilin 1000 mg 2 times a day, with a gradual decrease in dosage to 400 mg 2 times a day, for a month; sermion 400 mg once a day for 10 days; Cavinton 5 mg 2 times a day for a month. Two weeks after the course, they begin taking vazobral 2 ml 2 times a day and pantogam 250 mg 1 time a day for a month, followed by taking glycine 1/2 tab. at night under the tongue, later increasing the dose to 1 tablet.
With paresis of the VII nerve, physical methods of treatment are widely used in the absence of contraindications (severe general condition of the patient, trophic disorders in the face, the presence of blood in the cerebrospinal fluid, the development of meningoencephalitis after injury). Minina on the affected half of the face, 10-15 minutes daily. Apply iodine-electrophoresis of the ear endoaurally. To do this, the ear canal and auricle are filled with a gauze swab dipped in a medicinal solution; an electrode-cathode is placed on the swab. The second electrode 6 x 8 cm is placed on the opposite cheek, the current strength is 1-2 mA, 15-20 minutes, every other day or every day. Galvanization is also used with a current strength of 1 mA to 5 mA for 15-20 minutes, 10-15 procedures. Often shown electrophoresis with prozerin 0.1% and Yu 2% in the form of Bourguignon's half mask; current strength from 1 mA to 3-5 mA for 20 minutes, 10-15 sessions per course; UHF with a power of 40-60 watts at a distance of electrodes 2 cm from the face for 10-15 minutes, without feeling warm, 10-15 sessions per course.
To restore the functions of the facial muscles, it is advisable to use electrical stimulation. It starts 3-4 weeks after the injury, taking into account the data of electrodiagnostics. Usually, a technique is used in which stimulation with current is combined with “volitional” movements - the method of so-called “active” stimulation. with an area of 2-3 sq. cm, pulsed current with a pulse frequency of 100 and a current of 8-16 mA). With the appearance of a pronounced pain reaction, the current strength decreases.
Shown is the heat treatment in the form of paraffin, ozocerite and mud applications (duration of sessions 15-20 minutes, temperature 50-52 ° C, for a course of 12-18 procedures). Thermal applications should cover the face, mastoid process and neck area.
Complications
Motor deficit due to paresis of the VII nerve leads not only to a cosmetic defect, but also violates the usefulness of the acts of chewing and swallowing, changes the phonation. Neuroparalytic keratitis, the cause of which in patients with lesions of the facial nerve is lagophthalmos and impaired lacrimation, ultimately leads to corneal scarring, up to the loss of the eye. All taken together reduces the quality of life of the victim and inflicts severe mental trauma on him.
CAUDAL NERVE INJURIES
Caudal nerves suffer from: severe TBI, when the brain stem is damaged, craniocervical injury with damage to the atlas, penetrating wounds of the craniocervical region with damage to the soft tissues of the neck. A case of paralysis of the tongue due to traction detachment of both nerves from the base of the skull in case of a head injury is described.
With bilateral damage to the glossopharyngeal nerve, motor disorders can be one of the manifestations of bulbar palsy, which occurs with combined damage to the nuclei, roots, or trunks of the IX, X, XII nerves. If the vagus nerve is damaged, disorders of swallowing, voice formation, articulation and breathing develop (bulbar palsy). Lesions of the vagus nerve are manifested by symptoms of irritation or phenomena of loss of its function.
In case of damage to the caudal nerves, conservative therapy is prescribed to improve the conduction of excitation in neuromuscular synapses and restore neuromuscular conduction (prozerin 0.05%, 1 ml subcutaneously daily for 10 days, then galantamine 1%, 1 ml subcutaneously; oksazil 0.05, gliatilin 1 g twice daily Prevention of aspiration of food and saliva is important.
With paralysis of the trapezius muscles, a surgical reconstruction of the accessory nerve is performed on its extra cranial segments. A description of the reconstruction of intracranial segments was not found in the literature. Damage to the hypoglossal nerve is often combined with damage to the extracranial part of the carotid artery (on the neck). In this regard, reconstructive surgery is performed in the acute phase of injury using microsurgical techniques.
O.N.Dreval, I.A.Shirshov, E.B.Sungurov, A.V.Kuznetsov
1. Olfactory nerve - has no nuclei, olfactory cells are located in the mucous membrane of the olfactory region of the nasal cavity. Contains visceral sensory fibers.
The exit from the brain is from the olfactory bulb.
The exit from the skull is from the ethmoid plate of the ethmoid bone.
The nerve is a collection of 15-20 thin nerve threads, which are the central processes of the olfactory cells. They pass through holes in the ethmoid bone and then end in the olfactory bulb, which continues into the olfactory tract and triangle.
2. Optic nerve - has no nuclei, ganglionic neurocytes are located in the retina of the eyeball. Contains somatic sensory fibers.
Exit from the brain - optic chiasm at the base of the brain
Exit from the skull - optic canal
Moving away from the posterior pole of the eyeball, the nerve leaves the orbit through the optic canal and, entering the cranial cavity together with the same nerve of the other side, forms the optic chiasm, which lies in the optic groove of the sphenoid bone. The continuation of the optic pathway beyond the chiasm is the optic tract, ending in the lateral geniculate body and in the superior colliculus of the roof of the midbrain.
3. Oculomotor nerve - has 2 nuclei: autonomic and motor, located in the tegmentum of the midbrain (at the level of the upper mounds). Contains efferent (motor) fibers to most of the external muscles of the eyeball and parasympathetic fibers to the internal eye muscles (ciliary muscles and muscles that narrow the pupil).
The exit from the brain is from the medial sulcus of the brain stem / interpeduncular fossa / from the oculomotor sulcus.
The oculomotor nerve leaves the brain along the medial edge of the brain stem, then goes to the superior orbital fissure, through which it enters the orbit.
Entering the orbit is divided into 2 branches:
A) Superior branch - to the superior rectus muscle of the eyeball and to the muscle that lifts the upper eyelid.
B) The lower branch - to the lower and medial rectus muscles of the eyeball and the lower oblique muscle of the eyeball. From the lower branch the nerve root departs to the ciliary node, carrying parasympathetic fibers for the ciliary muscle and the muscle that narrows the pupil.
4. Block nerve - has 1 motor nucleus, located in the tegmentum of the midbrain (at the level of the lower mounds). Contains only efferent (motor) fibers.
The exit from the brain is from under the lower hillocks / on the sides of the frenulum of the upper medullary velum.
The exit from the skull is the superior orbital fissure.
After leaving the brain, it goes around the brain stem laterally and through the superior orbital fissure enters the orbit, where it innervates the superior oblique muscle of the eyeball.
5. Trigeminal nerve - has 4 nuclei: 3 sensory and 1 motor nucleus. Located in the tegmentum of the midbrain, the tegmentum of the bridge, the tegmentum of the medulla oblongata. Contains afferent (sensory) fibers and efferent (motor) fibers.
The exit from the brain is the place of the bridge and the middle cerebellar peduncle.
The exit from the skull is the ophthalmic nerve - the superior orbital fissure, the maxillary nerve - a round hole, the mandibular nerve - an oval hole.
Branches of the trigeminal nerve:
1. The ophthalmic nerve enters the orbital cavity through the superior orbital fissure, but before entering it it is divided into 3 more branches:
a) The frontal nerve, runs directly anteriorly under the roof of the orbit through the supraorbital notch (or foramen) into the skin of the forehead, here it is called the supraorbital nerve, giving branches along the way into the skin of the upper eyelid and medial angle of the eye.
b) Lacrimal nerve, go to the lacrimal gland and, passing through it, ends in the skin and conjunctiva of the lateral corner of the eye. Before entering the lacrimal gland, it connects to the zygomatic nerve (from the second branch of the trigeminal nerve). Through this anastomosis, the lacrimal nerve receives secretory fibers for the lacrimal gland and supplies it with sensory fibers as well.
c) Nasociliary nerve, innervates the anterior part of the nasal cavity (anterior and posterior ethmoid nerves), the eyeball (long ciliary nerves), the skin of the medial angle of the eye, the conjunctiva and the lacrimal sac (subtrochlear nerve).
2. The maxillary nerve exits the cranial cavity through a round opening into the pterygopalatine fossa; from here, its direct continuation is the infraorbital nerve, which goes through the inferior orbital fissure to the infraorbital groove and canal on the lower wall of the orbit and then exits through the supraorbital foramen to the face, where it splits into a bundle of branches. These branches, connecting with the branches of the facial nerve, innervate the skin of the lower eyelid, lateral surface of the nose and lower lip..
Branches of the maxillary and its continuation of the infraorbital nerves:
a) Zygomatic nerve, Inn. skin of the cheek and anterior part of the temporal region.
b) The upper alveolar nerves, in the thickness of the upper jaw, form a plexus, from which the upper alveolar branches and branches innervating the upper gums depart.
c) Nodal nerves connect the maxillary nerve with the pterygopalatine ganglion, which belongs to the autonomic nervous system.
3. The mandibular nerve, has in its composition, in addition to the sensory, the entire motor root of the trigeminal nerve. Upon exiting the skull through the foramen ovale, it divides into 2 groups of branches:
a) Muscular branches: to all the masticatory muscles, to the muscle that strains the palatine curtain, to the muscle that strains the eardrum, to the maxillohyoid muscle and the anterior belly of the digastric muscle, the corresponding nerves go.
b) Sensitive branches:
- The buccal nerve goes to the buccal mucosa.
The lingual nerve is located under the mucous membrane of the floor of the mouth.
Having given the hypoglossal nerve to the mucous membrane of the floor of the mouth, it innervates the mucous membrane of the back of the tongue for the anterior two-thirds. It is joined by a thin branch emerging from the stony-tympanic fissure, carrying parasympathetic fibers from the superior salivary nucleus (related to the facial nerve) - a tympanic string, which will provide innervation for the hyoid and sublingual salivary glands. The drum string also carries taste fibers from the anterior two-thirds of the tongue.
3. The lower alveolar nerve, through the mandibular foramen, together with the artery of the same name, goes into the canal of the lower jaw, where it gives branches to all the lower teeth, having previously formed a plexus. At the anterior end of the mandibular canal, the nerve gives off a thick branch - the mental nerve, which emerges from the mental foramen and extends into the skin of the chin and lower lip.
4. Auriculotemporal nerve, penetrates into the upper part of the parotid gland and goes to the temporal region, accompanying the superficial temporal artery. Gives secretory branches to the parotid gland, as well as sensitive fibers to the temporomandibular joint, to the skin of the anterior part of the auricle, external auditory canal and to the skin of the temple.
6. Abducens nerve - has one motor nucleus located in the pons tire. Contains only
The exit from the brain is from the groove between the bridge and the pyramid.
The exit from the skull is the superior orbital fissure.
It leaves the brain between the bridge and the pyramid, passes through the superior orbital fissure into the orbit and enters the lateral rectus muscle of the eyeball.
7. Facial nerve - incorporates motor, autonomic and sensory nuclei, located in the cover of the bridge. It contains efferent (motor), afferent (sensory) and parasympathetic fibers.
The exit from the brain is behind the middle cerebellar peduncle / cerebellopontine angle.
Exit from the skull - internal auditory canal - facial canal - stylomastoid opening.
The facial nerve enters the surface of the brain laterally along the posterior edge of the pons, next to the vestibulocochlear nerve. Then, together with the last nerve, it enters the internal auditory meatus and enters the facial canal. In the canal, the nerve first goes horizontally, heading outward, then in the area of the gap of the canal of the large stony nerve, it turns back at a right angle and also runs horizontally along the inner wall of the tympanic cavity in its upper part. Having passed the limits of the tympanic cavity, the nerve again bends and descends vertically down, leaving the skull through the stylomastoid foramen. When exiting, the nerve enters the thickness of the parotid gland and is divided into terminal branches.
Gives the following branches before exiting the channel :
- The large stony nerve originates in the area of the knee and exits through the gap of the canal of the large stony nerve; then it goes along the groove of the same name on the anterior surface of the pyramid of the temporal bone, passes into the pterygoid canal along with the sympathetic nerve, the deep stony nerve, forming with it the nerve of the pterygopalatine canal and reaches the pterygopalatine node.
The nerve is interrupted at the node and its fibers as part of the posterior nasal and palatine nerves go to the glands of the mucous membrane of the nose and palate; part of the fibers in the zygomatic nerve through connections with the lacrimal nerve reaches the lacrimal gland. The posterior nasal branches also give off the nasopalatine nerve to the glands of the mucous membrane of the hard palate. The palatine nerves innervate the glands of the mucous membrane of the soft and hard palate.
- stapedial nerve, innervates the corresponding muscle.
- drum string, having separated from the facial nerve in the lower part of the facial canal, penetrates into the tympanic cavity, lies there on the medial surface of the tympanic membrane, and then leaves through the stony-tympanic fissure; leaving the gap to the outside, it joins the lingual nerve, supplying the anterior two-thirds of the tongue with taste fibers. The secretory part approaches the submandibular node and, after a break in it, supplies the submandibular and sublingual salivary glands with secretory fibers.
After exiting the stylomastoid foramen, it gives the following branches:
- Posterior ear nerve, innervates the posterior ear muscle and the occipital abdomen of the cranial vault.
- Digastric branch, innervates the posterior belly of the digastric muscle and the stylohyoid muscle.
- parotid plexus, formed by numerous branches to the facial muscles of the face:
Temporal branches - Inn. upper and anterior ear muscles, frontal belly of the cranial vault, circular muscle of the eye;
Zygomatic branches - inn. circular muscle of the eye and zygomatic muscle;
Buccal branches - to the muscles of the circumference of the mouth and nose;
Marginal mandibular branch - a branch that runs along the edge of the lower jaw to the muscles of the chin and lower lip;
Neck branch - inn. superficial neck muscle.
Intermediate nerve, is a mixed nerve. It contains afferent (gustatory) fibers going to its sensory nucleus (single nucleus) and efferent (secretory, parasympathetic) fibers coming from its autonomic (secretory) nucleus (superior salivary nucleus). The intermediate nerve exits the brain as a thin trunk between the facial and vestibulocochlear nerves, after passing some distance, joins the facial nerve, becomes its integral part. Further, it passes into a large stony nerve. Conducts sensory impulses from the taste buds of the anterior part of the tongue and soft palate. Secretory parasympathetic fibers are sent to the submandibular and sublingual salivary glands.
8. Vestibulocochlear nerve, has in its composition 6 sensitive nuclei located in the cover of the bridge. It contains only afferent (sensory) fibers.
The exit from the brain is lateral to the facial nerve, from the cerebellopontine angle.
The exit from the skull is the internal auditory meatus.
It consists of two parts: the vestibular part and the cochlear part. Sensory fibers are responsible for the specific innervation of the organ of hearing (fibers from the cochlear nuclei; cochlear part) and the specific innervation of the balance organ (fibers from the vestibular nuclei; vestibular part).
9. The glossopharyngeal nerve has 3 different nuclei: motor, autonomic and sensory, located in the tegmentum of the medulla oblongata. It contains efferent (motor) fibers, parasympathetic fibers and afferent (motor) fibers.
Out of the brain - lateral to the two previous nerves / from the posterolateral groove, behind the olive.
The glossopharyngeal nerve emerges with its roots from the medulla oblongata behind the olive, above the vagus nerve, and together with the latter leaves the skull through the jugular foramen. Within the jugular foramen, the sensitive part of the nerve forms the upper node, and upon exiting the hole, the lower node, which lies on the lower surface of the temporal bone pyramid. The nerve descends, first between the internal jugular vein and the internal carotid artery, and then goes around the stylohyoid muscle from behind and, along the lateral side of this muscle, approaches the root of the tongue in a gentle arc, where it divides into terminal branches.
Branches of the glossopharyngeal nerve:
The tympanic nerve departs from the lower node and enters the tympanic cavity, where it forms the tympanic plexus, to which branches also come from the sympathetic plexus with the internal carotid artery. This plexus innervates the mucous membrane of the tympanic cavity and the auditory tube. After exiting the tympanic cavity through the upper wall, it will be called the small stony nerve, which passes to the groove of the same name, along the anterior surface of the temporal bone pyramid and reaches the ear node.
Parasympathetic secretory fibers for the parotid gland are brought to this node; after switching fibers at this node, the postganglionic fibers go as part of the auriculotemporal nerve (the third branch of the trigeminal nerve).
The stylo-pharyngeal branch innervates the muscle of the same name.
Tonsil branches innervate the mucous membrane of the palatine tonsils and arches.
Pharyngeal branches go to the pharyngeal plexus.
The lingual branches, the terminal branches of the glossopharyngeal nerve, are sent to the mucous membrane of the posterior third of the tongue, supplying sensory fibers, among which the taste fibers also pass.
Branch of the carotid sinus, sensory nerve to the carotid sinus.
10. The vagus nerve has 3 different nuclei: motor, autonomic and sensory nuclei, located in the tegmentum of the medulla oblongata. It contains efferent (motor), afferent (sensory) and parasympathetic fibers.
The exit from the brain is from the posterolateral groove, behind the olive.
The exit from the skull is the jugular foramen.
Fibers of all kinds exit the medulla oblongata in its posterior lateral groove, below the glossopharyngeal nerve, in 10-15 roots, which form a thick nerve trunk that leaves the cranial cavity through the jugular foramen. In the jugular foramen, the sensitive part of the nerve forms top node, and after leaving the hole bottom knot. Upon exiting the cranial cavity, the vagus nerve trunk descends to the neck behind the vessels in the groove, first between the internal jugular vein and the internal carotid artery, and then between the same vein and the common carotid artery.
The vagus nerve then passes through the superior thoracic inlet into the thoracic cavity, where its right trunk is located in front of the subclavian artery, and the left one is on the front side of the aortic arch. Going down, both vagus nerves bypass the root of the lung behind on both sides and accompany the esophagus, forming plexuses on its walls, moreover, the left nerve - passes along the front side, and the right - along the right side. Together with the esophagus, both vagus nerves penetrate through the esophageal opening into the abdominal cavity, where they form plexuses on the walls of the stomach.
Branches of the vagus nerves:
A) At the head:
Meningeal branch - Inn. hard shell of the brain in the region of the posterior cranial fossa.
Ear branch - Inn. the back wall of the external auditory canal and part of the skin of the auricle.
B) In the neck:
The pharyngeal nerves, together with the branches of the glossopharyngeal nerve, form the pharyngeal plexus; pharyngeal branches of the vagus nerve innervate constrictors of the pharynx, muscles of the palatine arches and soft palate; the pharyngeal plexus also provides sensory innervation to the pharyngeal mucosa.
The superior laryngeal nerve supplies sensory fibers to the mucous membrane of the larynx above the glottis, part of the root of the tongue and epiglottis, and motor fibers - part of the muscles of the larynx and the lower constrictor of the pharynx.
3. Superior and inferior cardiac cervical branches, form the heart plexus.
B) In the chest:
The recurrent laryngeal nerve, on the right side, this nerve bends around the subclavian artery from below and behind, and on the left, also from below and behind the aortic arch and then rises upward in the groove between the esophagus and trachea, giving numerous esophageal and tracheal branches. The end of the nerve, called the lower laryngeal nerve, innervates part of the muscles of the larynx, its mucous membrane below the vocal folds, the mucous membrane of the root of the tongue near the epiglottis, as well as the trachea, pharynx and esophagus, thyroid and thymus glands, lymph nodes of the neck, heart and mediastinum.
Cardiac thoracic branches go to the cardiac plexus.
Bronchial and tracheal branches, parasympathetic, together with the branches of the sympathetic trunk form the pulmonary plexus on the walls of the bronchi. Due to the branches of this plexus, the muscles and glands of the trachea and bronchi are innervated, and in addition, it contains sensory fibers for the trachea, bronchi and lungs.
Esophageal branches go to the wall of the esophagus.
D) in the abdomen:
The plexus of the vagus nerves, going through the esophagus, continues to the stomach, forming pronounced trunks (anterior and posterior). The continuation of the left vagus nerve, descending from the anterior side of the esophagus to the anterior wall of the stomach, forms anterior gastric plexus, located mainly along the lesser curvature of the stomach, from which depart mixed with sympathetic branches anterior gastric branches.
The continuation of the right vagus nerve, descending along the posterior wall of the esophagus, is the posterior gastric plexus, in the region of the lesser curvature of the stomach, which gives off the posterior gastric branches. In addition, most of the fibers of the right vagus nerve in the form of celiac branches go along with the left gastric artery to the celiac trunk, and from here along the branches of the vessels, along with the sympathetic plexuses, to the liver, spleen, pancreas, kidneys, small and large intestine to the sigmoid.
11. Accessory nerve, has 1 motor nucleus, located in the tegmentum of the medulla oblongata. It contains only efferent (motor) fibers.
The exit from the brain is from the same furrow as the vagus nerve, below it.
The exit from the skull is the jugular foramen.
According to the nuclei in the nerve, the cerebral and spinal parts are distinguished. cerebral part emerges from the medulla oblongata below the vagus nerve . spinal part accessory nerve is formed between the anterior and posterior roots of the spinal nerves (from 2-5) and partly from the anterior roots of the three upper cervical nerves, rises in the form of a nerve stem and joins the cerebral part. The accessory nerve, together with the vagus nerve, exits the cranial cavity through the jugular foramen and innervates the trapezius muscle of the back and the sternocleidomastoid muscle. The cerebral portion of the accessory nerve, together with the recurrent laryngeal nerve, innervates the muscles of the larynx.
12. The hypoglossal nerve has one motor nucleus located in the tegmentum of the medulla oblongata. Contains only efferent (motor) fibers.
The exit from the brain is the anterolateral sulcus of the medulla oblongata, between the pyramid and the olive.
The exit from the skull is the hyoid canal.
Appearing on the base of the brain between the pyramid and the olive with several roots, the nerve then passes in the canal of the same name of the occipital bone, descends down the lateral side of the internal carotid artery, passes under the posterior belly of the digastric muscle and goes in the form of an arc, convex downwards, along the lateral surface of the hyoid-lingual muscle. One of the branches of the nerve, the upper root, goes down, connects with the lower root of the cervical plexus and forms a cervical loop with it. From this loop, the muscles located below the hyoid bone are innervated. + Innervates the derivatives of the occipital myotomes - all the muscles of the tongue.
The person has 12 pairs of cranial nerves(see diagrams below). Scheme of localization of the nuclei of cranial nerves: anteroposterior (a) and lateral (b) projections
The red color indicates the nuclei of the motor nerves, blue - sensitive, green - the nuclei of the vestibulocochlear nerve
Olfactory, visual, vestibulocochlear - nerves of highly organized specific sensitivity, which in their morphological features represent, as it were, peripheral parts of the central nervous system.
The article below will list all 12 pairs of cranial nerves, information about which will be accompanied by tables, diagrams and figures.
For more convenient navigation through the article, there is a picture with clickable links above: just click on the name of the pair of CNs you are interested in and you will immediately be transferred to information about it.
12 pairs of cranial nerves
Motor nuclei and nerves are marked in red, sensory in blue, parasympathetic in yellow, predvernocochlear nerve in green
1 pair of cranial nerves - olfactory (nn. olfactorii)
NN. olfactorii (scheme) 2 pair of cranial nerves - visual (n. opticus)
N. opticus (diagram) With damage to the 2nd pair of cranial nerves, various types of visual impairment can be observed, shown in the figure below.
amaurosis (1);
hemianopsia — bitemporal (2); binasal (3); the same name (4); square (5); cortical (6).
Any pathology of the optic nerve requires a mandatory check of the fundus, the possible results of which are shown in the figure below.
Fundus examination
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Primary atrophy of the optic nerve. The color of the disk is gray, its borders are clear.
Secondary atrophy of the optic nerve. The color of the disk is white, the contours are fuzzy.3 pair of cranial nerves - oculomotor (n. oculomotorius)
N. oculomotorius (diagram) Innervation of the muscles of the eye
Scheme of innervation of the muscles of the eyeball by the oculomotor nerve 3rd pair of cranial nerves is involved in the innervation of the muscles involved in the movement of the eye.
Schematic representation of the path - this is a complex reflex act, in which not only 3 pairs, but also 2 pairs of cranial nerves participate. The diagram of this reflex is shown in the figure above.
4 pair of cranial nerves - block (n. trochlearis)
5 pair of cranial nerves - trigeminal (n. trigeminus)
Kernels and central paths n. trigeminus The dendrites of sensitive cells form three nerves along their course (see the innervation zones in the figure below):
- orbital- (zone 1 in the figure),
- maxillary- (zone 2 in the figure),
- mandibular- (zone 3 in the figure).
Areas of innervation of the skin branches n. trigeminus From skull n. ophthalmicus exits through fissura orbitalis superior, n. maxillaris - through foramen rotundum, n. mandibularis - through the foramen ovale. As part of one of the branches n. mandibularis, which is called n. lingualis, and chorda tympani taste fibers are suitable for the sublingual and mandibular glands.
When involved in the process of the trigeminal node, all types of sensitivity suffer. This is usually accompanied by excruciating pain and the appearance of herpes zoster on the face.
When involved in the pathological process of the nucleus n. trigeminus, located in the spinal tract, the clinic is accompanied by dissociated anesthesia or hypesthesia. With a partial lesion, segmental annular zones of anesthesia are noted, known in medicine under the name of the scientist who discovered them " Zelder zones" (see diagram). When the upper parts of the nucleus are affected, the sensitivity around the mouth and nose is disturbed; lower - outer parts of the face. Processes in the nucleus are usually not accompanied by pain.
6 pair of cranial nerves - abducens (n. abducens)
Abducens nerve (n. abducens) - motor. The nerve nucleus is located in the inferior part of the pons, under the floor of the fourth ventricle, lateral and dorsal to the dorsal longitudinal bundle.
Damage to the 3rd, 4th, and 6th pairs of cranial nerves causes total ophthalmoplegia. With paralysis of all the muscles of the eye, there is external ophthalmoplegia.
The defeat of the above pairs, as a rule, is peripheral.
Eye innervation
Without the friendly functioning of several components of the muscular apparatus of the eye, it would be impossible to carry out the movements of the eyeballs. The main formation, thanks to which the eye can move, is the dorsal longitudinal bundle of fasciculus longitudinalis, which is a system that connects the 3rd, 4th and 6th cranial nerves with each other and with other analyzers. Cells of the nucleus of the dorsal longitudinal bundle (Darkshevich) are located in the cerebral peduncles laterally from the cerebral aqueduct, on the dorsal surface in the region of the posterior commissure of the brain and frenulum. The fibers go down along the aqueduct of the large brain to the rhomboid fossa and on their way approach the cells of the nuclei of 3, 4 and 6 pairs, carrying out the connection between them and the coordinated function of the eye muscles. The composition of the dorsal bundle includes fibers from the cells of the vestibular nucleus (Deiters), which form the ascending and descending pathways. The first ones contact with the cells of the nuclei of the 3rd, 4th and 6th pairs, the descending branches stretch down, pass in the composition, which end at the cells of the anterior horns, forming tractus vestibulospinalis. The cortical center, which regulates voluntary gaze movements, is located in the region of the middle frontal gyrus. The exact course of the conductors from the cortex is unknown; apparently, they go to the opposite side to the nuclei of the dorsal longitudinal bundle, then along the dorsal bundle to the nuclei of these nerves.
Through the vestibular nuclei, the dorsal longitudinal bundle is connected with the vestibular apparatus and the cerebellum, as well as with the extrapyramidal part of the nervous system, through the tractus vestibulospinalis - with the spinal cord.
7 pair of cranial nerves - facial (n. facialis)
N. facialis The scheme of the topography of the facial nerve is presented above.
Intermediate nerve (n. intermedius)
Paralysis of mimic muscles: a - central;
b - peripheral.
The intermediate nerve is essentially part of the facial.
With damage to the facial nerve, or rather its motor roots, there is paralysis of the mimic muscles of the peripheral type. The central type of paralysis is a rare phenomenon and is observed when the pathological focus is localized in, in particular, in the precentral gyrus. The differences between the two types of mimic muscle paralysis are shown in the figure above.
8 pair of cranial nerves - vestibulocochlear (n. vestibulocochlearis)
The vestibulocochlear nerve anatomically has two roots with completely different functional abilities (this is reflected in the name of the 8th pair):
- pars cochlearis, performing the auditory function;
- pars vestibularis, which performs the function of a static feeling.
Pars cochlearis
Other names for the root: "lower cochlear" or "cochlear part".
Cranial nerves - twelve pairs of nerves of the brain; there is also an intermediate nerve, which some authors consider the XIII pair. The cranial nerves are located at the base of the brain (Fig. 1). Part of the cranial nerves has predominantly motor functions (III, IV, VI, XI, XII pairs), others are sensitive (I, II, VIII pairs), the rest are mixed (V, VII, IX, X, XIII pairs). Some cranial nerves contain parasympathetic and sympathetic fibers.
Rice. 1. The base of the brain. Exit sites of cranial nerves:
a - olfactory bulb;
b - optic nerve;
c - olfactory tract;
d - oculomotor nerve;
d - trochlear nerve;
e - trigeminal nerve;
g - abducens nerve;
h - facial and intermediate nerves;
i - vestibulocochlear nerve;
to - glossopharyngeal and vagus nerves;
l - hypoglossal nerve;
m - accessory nerve.
I couple olfactory nerve(n. olfactorius), originates from the nerve cells of the nasal mucosa. Thin fibers of this nerve pass through the holes of the ethmoid plate of the ethmoid bone, enter the olfactory bulb, which then passes into the olfactory tract. Expanding backwards, this tract forms an olfactory triangle. At the level of the olfactory tract and the triangle lies the olfactory tubercle, in which the fibers coming from the olfactory bulb end. In the cortex, olfactory fibers are distributed in the hippocampus. When the olfactory nerve is damaged, there is a complete loss of smell - anosmia or a partial violation of it - hyposmia.
II pair, optic nerve(n. opticus), starts from the cells of the ganglionic layer of the retina. The processes of these cells are collected in the optic nerve, which, after entering the cavity, forms an optic chiasm, or chiasma, on the basis of the brain. But this decussation is not complete, only the fibers coming from the inner halves of the retina of the eyes intersect in it. After decussation, the optic nerve is called the optic tract, which ends in the lateral geniculate body. From the external geniculate body, the central visual pathway begins, which ends in the cortex of the occipital lobe of the brain. With any pathological processes in the brain affecting the optic chiasm, optic tract or path, various forms of prolapse occur - hemianopsia.
Diseases of the optic nerve can be inflammatory (neuritis), congestive (stagnant nipple) and dystrophic (atrophy) character.
The cause of optic neuritis can be various diseases (meningitis, arachnoiditis, influenza, etc.).
Manifested by a sudden decrease in visual acuity and narrowing of the field of view.
Congestive nipple is the most important symptom of increased intracranial pressure, which can be most often associated with a brain tumor, occasionally gumma, solitary tubercle, cyst, etc. Congestive nipple does not lead to visual impairment for a long time and is detected when examining the fundus. With the progression of the disease, it decreases and may occur.
Optic nerve atrophy can be primary (with cerebral syphilis, multiple sclerosis, with optic nerve injury, etc.) or secondary, as the outcome of neuritis or congestive nipple. With this disease, there is a sharp decrease in visual acuity up to complete blindness, as well as a narrowing of the visual field.
Treatment depends on the etiology of the disease.
Rice. 2. Scheme of the visual pathways.
III pair, oculomotor nerve(n. oculomotorius), formed by fibers coming from the nuclei of the same name, lying in the central gray matter, under the aqueduct of the brain (Sylvian aqueduct). It enters the base of the brain between its legs through the superior orbital fissure, penetrates the orbit and innervates all the muscles of the eyeball, with the exception of the superior oblique and external rectus muscles. The parasympathetic fibers contained in the oculomotor nerve innervate the smooth muscles of the eye. The defeat of the III pair is characterized by the drooping of the upper eyelid (), divergent strabismus and mydriasis (pupil dilation).
