What nerves innervate the smooth muscles of the eye. Oculomotor muscles

04.06.2020

17-09-2011, 13:32

Description

Sensory innervation of the eye and orbital tissues is carried out by the first branch of the trigeminal nerve - the orbital nerve, which enters the orbit through the superior orbital fissure and is divided into 3 branches: lacrimal, nasal and frontal.

The lacrimal nerve innervates the lacrimal gland, the outer conjunctiva of the eyelids and eyeball, the skin of the lower and upper eyelids.

The nasal nerve gives off a branch to the ciliary node, 3-4 long ciliary branches go to the eyeball, in the suprachoroidal space at ciliary body they form a dense plexus, the branches of which penetrate into the cornea. At the edge of the cornea, they enter the middle sections of its own substance, while losing their myelin coating. Here, the nerves form the main corneal plexus. Its branches under the anterior boundary plate (Bowman's) form one plexus of the "closing chain" type. The stems coming from here, piercing the borderline plate, fold on its front surface into the so-called subepithelial plexus, from which branches extend, ending with end sensitive devices directly in the epithelium.

The frontal nerve is divided into two branches: the supraorbital and supra-block. All the branches, anastomosing with each other, innervate the middle and inner part of the upper eyelid skin.

Ciliary, or ciliary, the node is located in the orbit on the outside of the optic nerve at a distance of 10-12 mm from the posterior pole of the eye. Sometimes there are 3-4 nodes around the optic nerve. The ciliary node includes sensory fibers of the rhinoceros nerve, parasympathetic fibers of the oculomotor nerve, and sympathetic fibers of the plexus of the internal carotid artery.

4-6 short ciliary nerves depart from the ciliary node, penetrating into the eyeball through the posterior part of the sclera and supplying the eye tissues with sensitive parasympathetic and sympathetic fibers. Parasympathetic fibers innervate the sphincter of the pupil and the ciliary muscle. Sympathetic fibers go to the muscle that dilates the pupil.

The oculomotor nerve innervates all the rectus muscles except the external one, as well as the lower oblique, which lifts the upper eyelid, the sphincter of the pupil and the ciliary muscle.

The blocky nerve innervates the superior oblique muscle, the abducens nerve - the external rectus muscle.

The circular muscle of the eye is innervated by a branch of the facial nerve.

Accessory apparatus of the eye

The accessory apparatus of the eye includes the eyelids, conjunctiva, lacrimal and lacrimal organs, retrobulbar tissue.

Eyelids (palpebrae)

The main function of the eyelids is protective. The eyelids are a complex anatomical formation that includes two sheets - musculocutaneous and conjunctival cartilage.

The skin of the eyelids is thin and very mobile, freely folds when the eyelids are opened and also freely straightens when they are closed. Due to mobility, the skin can easily pull to the sides (for example, scarring, causing eversion or curvature of the eyelids). Displacement, mobility of the skin, the ability to stretch and move is used in plastic surgery.

The subcutaneous tissue is represented by a thin and loose layer, poor in fatty inclusions. As a result, there are easily pronounced edemas in local inflammatory processes, hemorrhages in trauma. When examining a milestone wound, it is necessary to remember about the mobility of the skin and the possibility of a large displacement of the wounding object in the subcutaneous tissue.

The muscular part of the eyelid consists of the circular muscle of the eyelids, the muscle that lifts the upper eyelid, the Riolan muscles (a narrow muscle strip along the edge of the eyelid at the root of the eyelashes) and Horner's muscles (muscle fibers from the circular muscle that cover the lacrimal sac).

The circular muscle of the eye consists of palpebral and orbital bundles. The fibers of both bundles start from the inner ligament of the eyelids - a powerful fibrous horizontal cord, which is the formation of the periosteum of the frontal process upper jaw... The fibers of the palpebral and orbital parts are in arcuate rows. The fibers of the orbital part in the area of \u200b\u200bthe outer corner pass to the other eyelid and form a full circle. The circular muscle is innervated by the facial nerve.

The muscle that lifts the upper eyelid consists of 3 parts: the anterior part is attached to the skin, the middle part is attached to the upper edge of the cartilage, and the posterior part to the upper fornix of the conjunctiva. This structure ensures the simultaneous lifting of all layers of the eyelids. The anterior and posterior parts of the muscle are innervated by the oculomotor nerve, the middle - by the cervical sympathetic nerve.

Behind the orbicular muscle of the eye is a dense connective tissue plate called the cartilage of the eyelids, although it does not contain cartilage cells. Cartilage gives the eyelids a slight bulge that follows the shape of the eyeball. With the edge of the orbit, the cartilage is connected by a dense tarzoorbital fascia, which serves as the topographic border of the orbit. The content of the orbit includes everything that lies behind the fascia.

In the thickness of the cartilage, perpendicular to the edge of the eyelids are modified sebaceous glands - meibomian glands. Their excretory ducts enter the intermarginal space and are located along the posterior rib of the eyelids. The secret of the meibomian glands prevents tears from flowing through the edges of the eyelids, forms a lacrimal stream and directs it into the lacrimal lake, protects the skin from maceration, and is part of the precorneal film that protects the cornea from drying out.

The blood supply to the eyelids is carried out from the temporal side by branches from the lacrimal artery, and from the nasal side from the ethmoid. Both are the terminal branches of the orbital artery. The largest accumulation of eyelid vessels is located 2 mm from its edge. This must be taken into account when surgical interventions and injuries, as well as the location of the muscle bundles of the eyelids. Given the high displacement capacity of the eyelid tissues, it is desirable to minimize the removal of damaged areas during the initial surgical treatment.

The outflow of venous blood from the eyelids goes to the superior orbital vein, which has no valves and anastomoses through the angular vein with the cutaneous veins of the face, as well as with the veins of the sinuses and pterygopalatine fossa. The superior orbital vein leaves the orbit through the superior orbital fissure and flows into the cavernous sinus. Thus, an infection from the skin of the face, sinuses can quickly spread to the orbit and into the cavernous sinus.

The regional lymph node of the upper eyelid is the anterior lymph node, and the lower one is the submandibular. This must be taken into account when spreading infection and metastasizing tumors.

Conjunctiva

The conjunctiva is the thin mucous membrane that lines the back of the eyelids and the anterior surface of the eyeball down to the cornea. The conjunctiva is a mucous membrane richly supplied with blood vessels and nerves. She easily responds to any irritation.

The conjunctiva forms a slit-like cavity (sac) between the eyelid and the eye, which contains the capillary layer of the tear fluid.

In the medial direction, the conjunctival sac reaches the inner corner of the eye, where the lacrimal meatus and the semilunar fold of the conjunctiva (rudimentary third eyelid) are located. Laterally, the border of the conjunctival sac extends beyond the outer corner of the eyelids. The conjunctiva performs protective, moisturizing, trophic and barrier functions.

There are 3 divisions of the conjunctiva: the conjunctiva of the eyelids, the conjunctiva of the arches (upper and lower) and the conjunctiva of the eyeball.

The conjunctiva is a thin and delicate mucous membrane, consisting of superficial epithelial and deep - submucosal layers. The deep layer of the conjunctiva contains lymphoid elements and various glands, including the lacrimal glands, which provide mucin and lipid production for the superficial tear film that covers the cornea. The accessory lacrimal glands of Krause are located in the conjunctiva of the superior fornix. They are responsible for the constant production of tear fluid under normal, non-extreme conditions. Glandular formations can become inflamed, which is accompanied by hyperplasia of lymphoid elements, an increase in glandular discharge and other phenomena (folliculosis, follicular conjunctivitis).

The conjunctiva of the eyelids (tun. Conjunctiva palpebrarum) is moist, pale pinkish in color, but sufficiently transparent, through it you can see the translucent glands of the eyelid cartilage (meibomian glands). The superficial layer of the eyelid conjunctiva is lined with a multi-row columnar epithelium, which contains a large number of goblet cells that produce mucus. Under normal physiological conditions, this mucus is small. The goblet cells respond to inflammation by increasing the number and increasing secretion. When the conjunctiva of the eyelid is infected, the goblet cell discharge becomes mucopurulent or even purulent.

In the first years of life in children, the conjunctiva of the eyelids is smooth due to the absence of adenoid formations here. With age, you observe the formation of focal accumulations of cellular elements in the form of follicles, which determine the special forms of follicular lesions of the conjunctiva.

An increase in the glandular tissue predisposes to the appearance of folds, depressions and elevations that complicate the surface relief of the conjunctiva, closer to its arches, in the direction of the free edge of the eyelids, the folding is smoothed out.

The conjunctiva of the arches. In the vaults (fornix conjunctivae), where the conjunctiva of the eyelids passes into the conjunctiva of the eyeball, the epithelium changes from a multilayer cylindrical to a multilayer flat one.

Compared with other departments in the area of \u200b\u200bthe fornices, the deep layer of the conjunctiva is more pronounced. Here, numerous glandular formations up to small additional lacrimal jellies (Krause's glands) are well developed.

Under the transitional folds of the conjunctiva, there is a pronounced layer of loose tissue. This circumstance determines the ability of the vault conjunctiva to fold and expand easily, which allows the eyeball to maintain full mobility.

Cicatricial changes in the fornices of the conjunctiva limit eye movement. Loose tissue under the conjunctiva contributes to the formation of edema here during inflammatory processes or stagnant vascular phenomena. The superior conjunctival fornix is \u200b\u200bmore extensive than the inferior one. The depth of the first is 10-11 mm, and the second is 7-8 mm. Usually, the superior fornix of the conjunctiva extends beyond the superior orbitopalpebral sulcus, and the inferior fornix is \u200b\u200bat the level of the inferior orbitopalpebral fold. In the upper-outer part of the upper fornix, pinpoint holes are visible, these are the mouths of the excretory ducts of the lacrimal gland

The conjunctiva of the eyeball (conjunctiva bulbi). It distinguishes between a mobile part that covers the eyeball itself, and a part of the limbus region, soldered to the underlying tissue. From the limbus, the conjunctiva passes to the anterior surface of the cornea, forming its epithelial, optically completely transparent layer.

Genetic and morphological commonality of the epithelium of the conjunctiva of the sclera and cornea determines the possibility of the transition of pathological processes from one part to another. This occurs in trachoma even in its initial stages, which is essential for diagnosis.

In the conjunctiva of the eyeball, the adenoid apparatus of the deep layer is poorly represented, it is completely absent in the corneal region. The stratified squamous epithelium of the conjunctiva of the eyeball is non-keratinizing and retains this property under normal physiological conditions. The conjunctiva of the eyeball is much more abundant than the conjunctiva of the eyelids and fornices, it is equipped with sensitive nerve endings (the first and second branches of the trigeminal nerve). In this regard, getting into the conjunctival sac of even small foreign bodies or chemicals causes a very unpleasant sensation. It is more significant in conjunctival inflammation.

The conjunctiva of the eyeball is not connected with the underlying tissues in the same way everywhere. Along the periphery, especially in the upper outer part of the eye, the conjunctiva lies on a layer of loose tissue and here it can be freely moved with the instrument. This circumstance is used when performing plastic surgeries when it is required to move parts of the conjunctiva.

Along the perimeter of the limbus, the conjunctiva is fixed quite firmly, as a result of which, with significant edema, a vitreous shaft is formed in this place, sometimes hanging over the cornea with its edges.

The vascular system of the conjunctiva is part of the general circulatory system of the eyelids and eyes. The main vascular distributions are located in its deep layer and are represented mainly by the links of the microcircular network. Many intramural blood vessels the conjunctiva provide the vital activity of all its structural components.

By changing the pattern of the vessels of certain areas of the conjunctiva (conjunctival, pericorneal and other types of vascular injections), differential diagnosis of diseases associated with the pathology of the eyeball itself, with diseases of purely conjunctival origin is possible.

The conjunctiva of the eyelids and eyeball is supplied from the arterial arches of the upper and lower eyelids and from the anterior ciliary arteries. Arterial arches of the eyelids are formed from the lacrimal and anterior ethmoid arteries. The anterior ciliary vessels are branches of the muscular arteries that supply blood to the outer muscles of the eyeball. Each muscular artery gives off two anterior ciliary arteries. An exception is the artery of the external rectus muscle, which gives off only one anterior ciliary artery.

These vessels of the conjunctiva, the source of which is the ophthalmic artery, belong to the internal carotid artery system. However, the lateral arteries of the eyelids, from which the branches supplying part of the conjunctiva of the eyeball originate, anastomose with the superficial temporal artery, which is a branch of the external carotid artery.

The blood supply to most of the conjunctiva of the eyeball is carried out by branches originating from the arterial arches of the upper and lower eyelids. These arterial branches and their accompanying veins form the conjunctival vessels, which in the form of numerous trunks go to the conjunctiva of the sclera from both anterior folds. The anterior ciliary arteries of the scleral tissue extend over the region of attachment of the rectus tendons towards the limbus. 3-4 mm from it, the anterior ciliary arteries are divided into superficial and perforating branches, which penetrate through the sclera into the eye, where they participate in the formation of the large arterial circle of the iris.

The superficial (recurrent) branches of the anterior ciliary arteries and the accompanying venous trunks are the anterior conjunctival vessels. The superficial branches of the conjunctival vessels and the posterior conjunctival vessels anastomosed with them form the superficial (subepithelial) ate of the vessels of the conjunctiva of the eyeball. In this layer, the elements of the microcircular bed of the bulbar conjunctiva are most abundant.

The branches of the anterior ciliary arteries, anastomosed with each other, as well as the tributaries of the anterior ciliary veins, form the circumference of the limbus, the marginal or perilimbal vasculature of the cornea.

Lacrimal organs

The lacrimal organs consist of two separate topographically different departments, namely the lacrimal and the lacrimal. The tear performs a protective one (flushes out foreign elements from the conjunctival sac), trophic (nourishes the cornea that does not have its own vessels), bactericidal (contains non-specific factors immune defense - lysozyme, albumin, lactoferin, b-lysine, interferon), moisturizing function (especially the cornea, maintaining its transparency and being part of the precorneal film).

Tear-producing organs.

Lacrimal gland (glandula lacrimalis) in anatomical structure, it is very similar to salivary and consists of many tubular glands, collected in 25-40 relatively isolated lobules. The lacrimal gland is divided into two unequal parts by the lateral section of the aponeurosis of the muscle lifting the upper eyelid, the orbital and palpebral, which communicate with each other by a narrow isthmus.

The orbital part of the lacrimal gland (pars orbitalis) is located in the upper outer part of the orbit along its edge. Its length is 20-25 mm, its diameter is 12-14 mm and its thickness is about 5 mm. In shape and size, it resembles a bean, which adjoins the convex surface to the periosteum of the lacrimal fossa. In front of the gland, it is covered by the tarsoorbital fascia, and in the back it comes into contact with the orbital tissue. The gland is held by connective tissue strands stretched between the capsule of the gland and the periorbital.

The orbital part of the gland is usually not palpable through the skin, since it is located behind the bony edge of the orbit overhanging here. When the gland is enlarged (for example, swelling, swelling, or prolapse), palpation becomes possible. The lower surface of the orbital part of the gland faces the aponeurosis of the muscle that lifts the upper eyelid. The consistency of the gland is soft, grayish-red in color. The lobules of the anterior part of the gland are closed more tightly than in its posterior part, where they are loosened by fatty inclusions.

3-5 excretory ducts of the orbital part of the lacrimal gland pass through the substance of the lower lacrimal gland, receiving part of its excretory ducts.

Palpebral, or secular part The lacrimal gland is located somewhat anteriorly and below the superior lacrimal gland, directly above the superior fornix of the conjunctiva. When the upper eyelid is turned out and the eye is turned inward and downward, the lower lacrimal gland is normally visible as a slight protrusion of a yellowish tuberous mass. In the case of inflammation of the gland (dacryoadenitis), a more pronounced swelling is found in this place due to edema and compaction of the glandular tissue. The increase in the mass of the lacrimal gland can be so significant that it sweeps away the eyeball.

The lower lacrimal gland is 2-2.5 times smaller than the upper lacrimal gland. Its longitudinal size is 9-10 mm, transverse - 7-8 mm and thickness - 2-3 mm. The anterior edge of the inferior lacrimal gland is covered with the conjunctiva and can be felt here.

The lobules of the lower lacrimal gland are loosely interconnected, its ducts partly merge with the ducts of the upper lacrimal gland, some open into the conjunctival sac on their own. Thus, there are 10-15 excretory ducts of the upper and lower lacrimal glands in total.

The excretory ducts of both lacrimal glands are concentrated in one small area. Cicatricial changes in the conjunctiva in this place (for example, with trachoma) can be accompanied by obliteration of the ducts and lead to a decrease in the lacrimal fluid secreted into the conjunctival sac. The lacrimal gland comes into action only in special cases when a lot of tears are needed (emotions, foreign agent getting into the eye).

In a normal state, to perform all functions, 0.4-1.0 ml of tears produce small accessory lacrimal glands Krause (from 20 to 40) and Wolfring (3-4), embedded in the thickness of the conjunctiva, especially along its upper transitional fold. During sleep, the secretion of tears slows down dramatically. Small conjunctival lacrimal glands located in the boulevard conjunctiva provide the production of mucin and lipids necessary for the formation of the precorneal tear film.

The tear is a sterile, transparent, slightly alkaline (pH 7.0-7.4) and somewhat opalescent liquid, consisting of 99% water and approximately 1% organic and inorganic parts (mainly sodium chloride and sodium carbonates and magnesium, calcium sulfate and phosphate).

With various emotional manifestations, the lacrimal glands, receiving additional nerve impulses, produce an excess of fluid that flows from the eyelids in the form of tears. There are persistent disorders of lacrimation in the direction of hyper- or, conversely, hyposecretion, which is often a consequence of the pathology of nerve conduction or excitability. So, lacrimation decreases with paralysis of the facial nerve (VII pair), especially with damage to its geniculate node; paralysis of the trigeminal nerve (V pair), as well as some poisoning and severe infectious diseases with high fever. Chemical, painful temperature irritations of the first and second branches of the trigeminal nerve or zones of its innervation - the conjunctiva, the anterior parts of the eye, the nasal mucosa, solid meninges accompanied by profuse lacrimation.

The lacrimal glands have sensory and secretory (autonomic) innervation. General sensitivity of the lacrimal glands (provided by the lacrimal nerve from the first branch of the trigeminal nerve). Secretory parasympathetic impulses are delivered to the lacrimal glands by fibers of the intermediate nerve (n. Intermedrus), which is part of the facial nerve. Sympathetic fibers to the lacrimal gland originate from the cells of the upper cervical sympathetic node.

Lacrimal ducts.

They are designed to drain tear fluid from the conjunctival sac. Tear, as an organic liquid, provides normal vital activity and the function of the anatomical formations that make up the conjunctival cavity. The excretory ducts of the main lacrimal glands open, as mentioned above, into the lateral part of the superior fornix of the conjunctiva, which creates a semblance of a lacrimal "shower". From here, the tear spreads throughout the conjunctival sac. The posterior surface of the eyelids and the anterior surface of the cornea limit the capillary gap - the lacrimal stream (rivus lacrimalis). With movements of the eyelids, the tear moves along the lacrimal stream in the direction of the inner corner of the eye. Here is the so-called lacrimal lake (lacus lacrimalis), limited by the medial areas of the eyelids and the lunar fold.

The lacrimal duct itself includes the lacrimal openings (punctum lacrimale), the lacrimal tubules (canaliculi lacrimales), the lacrimal sac (saccus lacrimalis), the nasolacrimal duct (ductus nasolacrimalis).

Lacrimal points(punctum lacrimale) - these are the initial openings of the entire lacrimal apparatus. Their diameter is normally about 0.3 mm. The lacrimal points are located at the top of small, conical eminences called the lacrimal papillae (papilla lacrimalis). The latter are located on the posterior ribs of the free edge of both eyelids, the upper one by about 6 mm, and the lower one by 7 mm from their internal commissure.

The lacrimal papillae face the eyeball and almost adjoin it, while the lacrimal openings are immersed in the lacrimal lake, at the bottom of which the lacrimal meatus (caruncula lacrimalis) lies. Constant tension of the tarsal muscle, especially its medial sections, contributes to the close contact of the eyelids, and therefore the lacrimal openings with the eyeball.

The holes located at the top of the lacrimal papillae lead into the corresponding thin tubes - upper and lower lacrimal tubules ... They are located entirely in the thickness of the eyelids. Directionally, each tubule is subdivided into a short oblique vertical and a longer horizontal part. The length of the vertical sections of the lacrimal tubules does not exceed 1.5-2 mm. They run perpendicular to the edges of the eyelids, and then the lacrimal canals are wrapped towards the nose, taking a horizontal direction. The horizontal sections of the tubules are 6-7 mm long. The lumen of the lacrimal tubules is not the same throughout. They are somewhat narrowed in the bend area and ampullary widened at the beginning of the horizontal section. Like many other tubular formations, the lacrimal tubules have a three-layer structure. The outer, adventitious membrane is composed of delicate, thin collagen and elastic fibers. The middle muscular membrane is represented by a loose layer of bundles of smooth muscle cells, which, apparently, play a certain role in the regulation of the lumen of the tubules. The mucous membrane, like the conjunctiva, is lined with columnar epithelium. Such a device of the lacrimal tubules allows them to be stretched (for example, with mechanical action - the introduction of conical probes).

The end sections of the lacrimal canals, each individually or merging with each other, open in upper section a wider reservoir - the lacrimal sac. The mouth of the lacrimal tubules usually lie at the level of the medial commissure of the eyelids.

Lacrimal sac(saccus lacrimale) is the upper, expanded part of the nasolacrimal duct. Topographically, it refers to the orbit and is placed in its medial wall in the bone cavity - the fossa of the lacrimal sac. The lacrimal sac is a membranous tube 10-12 mm long and 2-3 mm wide. Its upper end ends blindly, this place is called the vault of the lacrimal sac. Downward, the lacrimal sac narrows and passes into the nasolacrimal duct. The wall of the lacrimal sac is thin and consists of a mucous membrane and a submucous layer of loose connective tissue. The inner surface of the mucous membrane is lined with multi-row columnar epithelium with a small number of mucous glands.

The lacrimal sac is located in a kind of triangular space formed by various connective tissue structures. Medially, the sac is limited by the periosteum of the lacrimal fossa, in front it is covered by the internal ligament of the eyelids and the tarsal muscle attached to it. The tarsoorbital fascia passes behind the lacrimal sac, as a result of which it is believed that the lacrimal sac is located preseptally, in front of the septum orbitale, i.e. outside the orbital cavity. In this regard, the purulent processes of the lacrimal sac extremely rarely give complications towards the tissues of the orbit, since the sac is separated from its contents by a dense fascial septum - a natural obstacle to infection.

In the area of \u200b\u200bthe lacrimal sac under the skin of the inner corner, a large and functionally important vessel passes - the angular artery (a.angularis). It is the link between the systems of the external and internal carotid arteries. An angular vein forms at the inner corner of the eye, which then continues into the facial vein.

Nasolacrimal duct (ductus nasolacrimalis) - a natural continuation of the lacrimal sac. Its length is on average 12-15 mm, width 4 mm, the duct is located in the bone canal of the same name. The general direction of the canal is from top to bottom, front to back, outside to inside. The course of the nasolacrimal canal varies somewhat depending on the width of the nasal dorsum and the pear-shaped opening of the skull.

Between the wall of the nasolacrimal duct and the periosteum of the bone canal there is a densely branched network of venous vessels, this is a continuation of the cavernous tissue of the inferior nasal concha. Venous formations are especially developed around the mouth of the duct. The increased blood filling of these vessels as a result of inflammation of the nasal mucosa causes temporary compression of the duct and its outlet, which prevents the tears from moving into the nose. This phenomenon is well known to all as lacrimation with acute rhinitis.

The mucous membrane of the duct is lined with two-layer cylindrical epithelium, small branched tubular glands are found here. Inflammatory processes, ulceration of the mucous membrane of the nasolacrimal duct can lead to scarring and its persistent narrowing.

The lumen of the outlet end of the nasolacrimal canal has a slit-like shape: its opening is located in the front of the lower nasal passage, 3-3.5 cm away from the entrance to the nose. Above this opening is a special fold, called the lacrimal fold, which represents a duplication of the mucous membrane and prevents the return flow of the tear fluid.

In the prenatal period, the mouth of the nasolacrimal duct is closed by a connective tissue membrane, which dissolves by the time of birth. However, in some cases, this membrane can persist, which requires urgent measures to remove it. Delay threatens the development of dacryocystitis.

The lacrimal fluid that irrigates the anterior surface of the eye partially evaporates from it, and the excess is collected in the lacrimal lake. The mechanism of lacrimation is closely related to the blinking movements of the eyelids. The main role in this process is attributed to the pump-like action of the lacrimal tubules, the capillary lumen of which, under the influence of the tone of their intramural muscle layer, coupled with the opening of the eyelids, expands and sucks in fluid from the lacrimal lake. When the eyelids are closed, the tubules are compressed and the tear is squeezed into the lacrimal sac. Of no small importance is the suction action of the lacrimal sac itself, which, during blinking movements, alternately expands and squeezes due to the traction of the medial ligament of the eyelids and the contraction of a part of their circular muscle, known as Horner's muscle. Further outflow of tears along the nasolacrimal duct occurs as a result of the expelling action of the lacrimal sac, and also partly under the influence of gravity.

The passage of the tear fluid along the lacrimal duct under normal conditions lasts about 10 minutes. Approximately so much time is required for (3% collargol, or fluorecein 1%) from the lacrimal lake to reach the lacrimal sac (5 minutes - tubular test) and then the nasal cavity (5 minutes - positive nasal test).

Oculomotor nerve, III (n. Oculomotorius) -motor. Its nucleus is located in front of the midbrain tectum at the level of the upper mounds of the midbrain roof. This nucleus consists of five groups of cells, different in structure and function. The two groups occupying the most lateral position form the lateral paired large-cell nucleus. The axons of the motor cells of this nucleus are directed mainly along their own and opposite sides to the following striated external muscles of the eye: the muscle that lifts the upper eyelid (m. Levator palpebrae superioris), the upper rectus muscle (i.e. rectus superior), which moves the eyeball upward and somewhat inward , the lower rectus muscle (m. rectus inferior), which moves the eyeball inward and downward, the medial rectus muscle (m. rectus medialis), which turns the eyeball Inward, and to the lower oblique muscle (m. obliquus inferior), which rotates the eyeball upward and outwards.

Between the two parts of the lateral (main) nucleus there are groups of small vegetative (parasympathetic) cells - an accessory nucleus, which includes the paired small-cell nucleus of Yakubovich, which innervates the unmarked (smooth) internal muscle of the eyeball, constricting the pupil (pupil sphincter), providing the pupil's response to light and convergence, and the unpaired small-cell nucleus of Perlia, located between the nuclei of Yakubovich, which innervates the ciliary muscle (m. ciliaris), which regulates the configuration of the lens, which ensures accommodation, that is, close vision.

The axons of the nerve cells of the paired and unpaired parasympathetic nuclei end in the ciliary node (ganglion ciliare), the cell fibers of which reach the mentioned muscles of the eye, participating in the implementation of the pupillary reflex.

The oculomotor nerve leaves midbrain through the bottom of the inter-peduncular fossa (fossa interpeduncularis) at the upper edge of the bridge and the medial surface of the cerebral peduncle and goes to the lower surface of the brain, where it passes together with the block, abducens and optic (branch of the V pair) nerves through the superior orbital fissure, leaving the cranial cavity and innervating the above five outer and two inner muscles of the eye.

Complete damage to the oculomotor nerve causes:

Ptosis of the upper eyelid (ptosis) caused by paresis or paralysis of m. levator palpebrae superioris;

Diverging squint (strabismus divergens) - due to paresis or paralysis of m. rectus medialis and the predominance of the function of m. rectus lateralis (VI nerve) - the eyeball is turned outward and downward;

Doubling in the eyes (diplo-pia), observed when raising the upper eyelid and increasing when the object in question moves towards the other eye,

Lack of convergence of the eyeballs due to the impossibility of eye movements inward and upward;

Disturbance of accommodation (due to paralysis of the ciliary muscle) - the patient cannot see an object at close range;

Dilation of the pupil (midriasis) due to the predominance of the sympathetic innervation of m. dilatatoris pupillae;

Protrusion of the eyeball from the orbit (exophtalmus) due to paresis or paralysis of the external muscles of the eye while maintaining the tone of m. orbitalis with sympathetic innervation from centrum cilio-spinale (Cs-Thi);

Lack of pupillary reflex.

Violation of the pupillary reflex is explained by the defeat of his reflex arc.

Illumination of one eye causes direct (pupil constriction on the illumination side) and friendly (constriction of the pupil of the opposite eye) pupillary reactions.

The study of the function of the oculomotor nerve is carried out simultaneously with the study of the functions of the block and abducent nerves. On examination, the symmetry of the palpebral fissures, the presence of ptosis (drooping of the upper eyelid), converging or diverging strabismus are determined. Then check for the presence of diplopia, movements of each eyeball separately (upward, downward, inward and outward) and joint movements of the eyeballs in these directions.

The study of the pupils is reduced to determining their size, shape, uniformity, as well as the direct and friendly reaction of the pupils to light. When examining the direct reaction of the pupil to light, the examiner, with his palms, closes both eyes of the subject, facing the light, and, alternately taking his palms away, looks at how the pupil reacts depending on the intensity of its illumination. In the study of a friendly response, the pupil's response to light is assessed depending on the illumination of the other eye.

The study of the reaction of the pupils to convergence with accommodation is carried out by alternately bringing the object closer to the eyes, then moving it away (at the level of the nose bridge). When approaching the object on which the gaze is fixed, the pupils narrow, with distance, they expand.

The loss of a direct and friendly reaction of the pupils to light while maintaining their vivid reaction to accommodation with convergence is called Argyll Robertson's syndrome, which is observed with dorsal tabes. With this disease, there are other symptoms of the pupils: their irregularity (anisocoria), a change in shape. In the chronic stage of epidemic encephalitis, the reverse Argyll Robertson syndrome is noted (the preservation of the reaction of the pupils to light, but the weakening or loss of the reaction of the pupils to convergence with accommodation).

In a nuclear lesion, only individual muscles are often affected, which is explained by the dispersed arrangement of cell groups and the involvement of only individual of them in the process.

Block nerve, IV (item trochlearis) - motor. Its nucleus is located in the lining of the midbrain at the bottom of the midbrain aqueduct at the level of the lower hillocks. The axons of the motor cells are directed dorsally, bypassing the aqueduct of the midbrain, and enter the superior cerebral sail, where they make a partial crossing. Leaving the ^ -brain trunk behind the lower hillocks, the root of the trochlear nerve bends around the cerebral peduncle along its lateral surface, lies on the base of the skull, and then, together with the oculomotor, abducens and optic nerves, leaves the cranial cavity through the superior orbital fissure and enters the orbit cavity. Here he innervates the only muscle - the superior oblique muscle, which turns the eyeball outward and downward.

An isolated lesion of the abducens nerve is rare. In this case, a converging squint (strabismus convergens) and diplopia occur only when looking down.

Abducens nerve, VI (item abducens) - motor. It also belongs to the group of nerves of the cerebellopontine angle. Its nucleus is located in the bottom of the upper triangle of the rhomboid fossa within the lower part of the bridge, where the inner knee of the facial nerve, bending around this nucleus, forms the facial tubercle. The axons of the motor cells of the nucleus are directed in the ventral direction and, having passed through the entire thickness of the bridge, exit the brainstem between the lower edge of the bridge and the pyramids of the medulla oblongata. Then the abducens nerve lies on the lower surface of the brain, passes near the cavernous sinus and leaves the cranial cavity through the superior orbital fissure (together with pairs III, IV and the upper branch of the V pair) and penetrates into the orbit, where it innervates the rectus lateral muscle, during the contraction of which the ocular the apple turns outward. The dendrites of the motor cells of the nucleus are in contact with the fibers of the posterior longitudinal bundle and the cortical-nuclear pathway. With damage to the V nerve, isolated peripheral paresis or paralysis of the rectus lateral muscle occurs, manifested by the restriction or inability to move

Zhenia of the eyeball outwards. In such cases, there is a convergent strabismus and diplopia, which increases when looking towards the affected nerve. Diplopia gives the patient great inconvenience. In order to avoid it, he tries to keep his head turned to the side opposite to the affected muscle, or cover his eyes with his hand. Prolonged double vision may be accompanied by dizziness, pain in the back of the head and neck due to the forced position of the head.

With a nuclear lesion, the pathological process involves both the fibers of the facial nerve, which envelop the nucleus of the abducens nerve, and the fibers of the pyramidal pathways (section “Alternating syndromes”, p. 130).

Innervation of the gaze. The friendly movements of the eyeballs are due to the synchronous contraction of muscles innervated by different nerves. So, turning the eyes up or down with the simultaneous lowering or raising of the eyelids requires muscle contraction, innervated by two oculomotor or two oculomotor and block nerves. The rotation of the eyeballs to the side is carried out due to muscle contraction, which are innervated by the abducens nerve corresponding to the side and the opposite oculomotor nerve. Such synchronicity is possible due to the existence of a special innervation system - the posterior longitudinal bundle connecting pairs III, IV and VI with each other and with other analyzers. Its descending fibers begin in the nucleus of the posterior longitudinal fascicle (Darkshevich), located under the bottom of the oral end of the midbrain aqueduct. They are joined by descending fibers from the lateral vestibular nucleus (Deiters). The descending fibers end at the nuclei of the XI nerve and the cells of the anterior horns of the cervical part of the spinal cord, providing a connection with head movements. On its way, the descending fibers approach the cells of the nuclei of pairs III, IV and VI, making a connection between them. In other vestibular nuclei - superior and medial - ascending fibers begin, which connect the nucleus of the VI nerve with that part of the nucleus of the opposite oculomotor nerve, which innervates the medial rectus muscle. The nuclei of the posterior longitudinal bundle connect together the parts of the nuclei of the oculomotor nerves responsible for turning the eyes up and down. This ensures consistent eye movements.

Voluntary eye movements are innervated by the cortex. The fibers connecting the cortical center of the gaze (posterior parts of the middle frontal gyrus) with the posterior longitudinal bundle pass through the anterior parts of the anterior leg of the inner capsule near the cortical-nuclear pathway and are sent to the lining of the midbrain and pons, crossing in its anterior parts. They end in the nucleus of the abducens nerve (brainstem center of gaze). Fibers for vertical movements the eyes approach the nucleus of the posterior longitudinal fasciculus, which is the focal point of the vertical gaze.

The defeat of the posterior longitudinal beam or the trunk center of the gaze causes a violation of the combined movements of the eyes to the side corresponding to the defeat (paresis or gaze paralysis). Damage to the posterior parts of the middle frontal gyrus or paths leading from here to the posterior longitudinal fasciculus causes paresis or paralysis of the gaze in the direction opposite to the lesion. During irritative processes in the cortex of the named sections, clonic-tonic convulsions of the eye muscles and head appear in the direction opposite to the focus of irritation. Damage to the area in which the nuclei of the posterior longitudinal fascicle are located causes paresis or paralysis of the vertical gaze.

The nervous system of the eye is represented by all types of innervation: sensitive, sympathetic and motor. Before penetrating into the eyeball, the anterior ciliary arteries give off a number of branches that form a marginal looped network around the cornea. The anterior ciliary arteries also give off branches that supply the conjunctiva adjacent to the limbus (anterior conjunctival vessels).

The nasal nerve gives off a branch to the ciliary node, the other fibers are long ciliary nerves. Without interrupting in the ciliary node, 3-4 ciliary nerves pierce the eyeball around the optic nerve and reach the ciliary body along the suprachoroidal space, where they form a dense plexus. From the latter, nerve branches penetrate the cornea.

In addition to the long ciliary nerves, short ciliary nerves originating from the ciliary node enter the eyeball in the same area. The ciliary node is a peripheral nerve ganglion and has a size of about 2 mm. It is located in the orbit on the outside of the optic nerve, 8-10 mm from the posterior pole of the eye.

The ganglion, in addition to the nasal fibers, includes parasympathetic fibers from the plexus of the internal carotid artery.

The short ciliary nerves (4–6) entering the eyeball provide all tissues of the eye with sensory, motor and sympathetic fibers.

Sympathetic nerve fibersthat innervate the pupil dilator enter the eye as part of the short ciliary nerves, but, joining them between the ciliary node and the eyeball, do not enter the ciliary node.

In the orbit, sympathetic fibers from the plexus of the internal carotid artery that do not enter the ciliary node are attached to the long and short ciliary nerves. The ciliary nerves enter the eyeball near the optic nerve. Short ciliary nerves coming from the ciliary node in the amount of 4-6, passing through the sclera, increase to 20-30 nerve trunks, distributed mainly in the vascular tract, and there are no sensory nerves in the choroid, and the sympathetic fibers that join in the orbit innervate the iris dilator shell. Therefore, with pathological processes in one of the membranes, for example, in the cornea, changes are noted both in the iris and in the ciliary body. Thus, the main part of the nerve fibers goes to the eye from the ciliary node, which is located 7-10 mm from the posterior pole of the eyeball and is adjacent to the optic nerve.

The ciliary node includes three roots: sensitive (from the nasal nerve - branches of the trigeminal nerve); motor (formed by parasympathetic fibers passing through the oculomotor nerve) and sympathetic. From four to six short ciliary nerves emerging from the ciliary node, branch into 20-30 more branches, which are directed along all structures of the eyeball. They are accompanied by sympathetic fibers from the upper cervical sympathetic ganglion, which do not enter the ciliary node, innervating the muscle that dilates the pupil. In addition, 3-4 long ciliary nerves (branches of the nasal ciliary nerve) pass into the eyeball, bypassing the ciliary node.

Motor and sensory innervation of the eye and its auxiliary organs. The motor innervation of the human organ of vision is realized with the help of the III, IV, VI, VII pairs of cranial nerves, the sensitive - through the first and partly the second branches of the trigeminal nerve (V pair of cranial nerves).

The oculomotor nerve (the third pair of cranial nerves) begins from the nuclei lying at the bottom of the Sylvian aqueduct at the level of the anterior hillocks of the quadruple. These nuclei are heterogeneous and consist of two main lateral (right and left), including five groups of large cells, and additional small-cell - two paired lateral (Yakubovich - Edinger - Westphal nucleus) and one unpaired (Perlia nucleus) located between them. The length of the nuclei of the oculomotor nerve in the anteroposterior direction is 5 mm.

From the paired lateral large-cell nuclei, there are fibers for the three straight (upper, inner and lower) and lower oblique oculomotor muscles, as well as for two portions of the muscle that lifts the upper eyelid, moreover, the fibers innervating the inner and lower straight, as well as the lower oblique muscles , immediately overlap.

Fibers extending from paired small-cell nuclei through the ciliary node innervate the sphincter muscle of the pupil, and those extending from the unpaired nucleus - the ciliary muscle. Through the fibers of the medial longitudinal bundle, the nuclei of the oculomotor nerve are connected with the nuclei of the trochlear and abducens nerves, the system of the vestibular and auditory nuclei, the nucleus of the facial nerve and the anterior horns of the spinal cord. Thanks to this, the reactions of the eyeball, head, trunk to all kinds of impulses, in particular vestibular, auditory and visual, are provided.

Through the superior orbital fissure, the oculomotor nerve enters the orbit, where, within the muscular funnel, it is divided into two branches - the upper and lower. The upper thin branch is located between the upper muscle and the muscle that lifts the upper eyelid, and innervates them. The lower, larger branch passes under the optic nerve and is divided into three branches - the outer (from it the root goes to the ciliary node and fibers for the lower oblique muscle), the middle and inner (the lower and internal rectus muscles are innervated, respectively). The root carries fibers from the accessory nuclei of the oculomotor nerve. They innervate the ciliary muscle and the sphincter of the pupil.

The block nerve (the fourth pair of cranial nerves) begins from the motor nucleus (length 1.5–2 mm), located at the bottom of the Sylvian aqueduct immediately behind the nucleus of the oculomotor nerve. Penetrates into the orbit through the superior orbital fissure lateral to the muscle funnel. It innervates the superior oblique muscle.

The abducens nerve (the sixth pair of cranial nerves) starts from the nucleus located in the pons varoli at the bottom of the rhomboid fossa. It leaves the cranial cavity through the superior orbital fissure, located inside the muscle funnel between the two branches of the oculomotor nerve. It innervates the external rectus muscle of the eye.

The facial nerve (the seventh pair of cranial nerves) has a mixed composition, that is, it includes not only motor, but also sensory, taste and secretory fibers that belong to the intermediate nerve. The latter is closely adjacent to the facial nerve at the base of the brain from the outside and is its posterior root.

The motor nucleus of the nerve (length 2–6 mm) is located in the lower part of the pons varoli at the bottom of the fourth ventricle. The fibers departing from it come out in the form of a root to the base of the brain in the cerebellopontine angle. Then the facial nerve, together with the intermediate one, enters the facial canal temporal bone... Here they merge into a common trunk, which further penetrates the parotid salivary gland and divides into two branches that form the parotid plexus. From it to the facial muscles, the nerve trunks extend, including the circular muscle of the eye.

The intermediate nerve contains secretory fibers for the lacrimal gland, located in the brain stem, and through the knee knot they enter the greater petrosal nerve. The afferent pathway for the main and accessory lacrimal glands begins with the conjunctival and nasal branches of the trigeminal nerve. There are other zones of reflex stimulation of tear production - the retina, anterior frontal lobe of the brain, basal ganglion, thalamus, hypothalamus and cervical sympathetic ganglion.

The level of damage to the facial nerve can be determined by the state of secretion of tear fluid. When it is not broken, the focus is below the knee node, and vice versa.

The trigeminal nerve (the fifth pair of cranial nerves) is mixed, that is, it contains sensory, motor, parasympathetic and sympathetic fibers. It contains nuclei (three sensitive - spinal, bridge, midbrain - and one motor), sensory and motor roots, as well as the trigeminal node (on the sensory root).

Sensory nerve fibers start from the bipolar cells of the powerful trigeminal ganglion, 14–29 mm wide and 5–10 mm long.

The trigeminal axons form the three main branches of the trigeminal nerve. Each of them is associated with certain nerve nodes: the optic nerve - with the ciliary, the maxillary - with the pterygopalatine and the mandibular - with the ear, submandibular and sublingual.

The first branch of the trigeminal nerve, being the thinnest (2–3 mm), leaves the cranial cavity through the orbital cleft. When approaching it, the nerve is divided into three main branches: n. nasociliaris, n. frontalis, n. lacrimalis.

The nasociliary nerve, located within the muscle funnel of the orbit, in turn, is divided into long ciliary ethmoid and nasal branches and, in addition, gives a root to the ciliary node.

Long ciliary nerves in the form of 3-4 thin trunks are directed to the posterior pole of the eye, perforate the sclera in the optic nerve circumference and along the suprachoroidal space are directed anteriorly along with short ciliary nerves extending from the ciliary body and around the corneal circumference. The branches of these plexuses provide sensitive and trophic innervation of the corresponding structures of the eye and the perilimbal conjunctiva. The rest of it receives sensitive innervation from the palpebral branches of the trigeminal nerve.

On the way to the eye, sympathetic nerve fibers from the plexus of the internal carotid artery are attached to the long ciliary nerves, which innervate the pupil dilator.

Short ciliary nerves (4–6) depart from the ciliary node, the cells of which, through the sensory, motor and sympathetic roots, are connected to the fibers of the corresponding nerves. It is located at a distance of 18–20 mm behind the posterior pole of the eye under the external rectus muscle, adjoining in this zone to the surface of the optic nerve.

Like long ciliary nerves, short ones also approach the posterior pole of the eye, perforate the sclera along the circumference of the optic nerve and, increasing in number (up to 20-30), participate in the innervation of the eye tissues, primarily its choroid.

The long and short ciliary nerves are the source of sensory (cornea, iris, ciliary body), vasomotor and trophic innervation.

The terminal branch of the nasociliary nerve is the subclavian nerve, which innervates the skin in the region of the root of the nose, the inner corner of the eyelids and the corresponding parts of the conjunctiva.

The frontal nerve, being the largest branch of the optic nerve, after entering the orbit gives off two large branches - the supraorbital nerve with medial and lateral branches and the supra-block nerve. The first of them, having perforated the tarzoorbital fascia, passes through the nasopharyngeal opening of the frontal bone to the skin of the forehead, and the second comes out of the orbit at its internal ligament. In general, the frontal nerve provides sensory innervation to the midsection of the upper eyelid, including the conjunctiva, and to the forehead.

The lacrimal nerve, entering the orbit, goes anteriorly over the external rectus muscle of the eye and is divided into two branches - the upper (larger) and lower. The upper branch, being a continuation of the main nerve, gives off branches to the lacrimal gland and conjunctiva. Some of them, after passing through the gland, perforate the tarsoorbital fascia and innervate the skin in the outer corner of the eye, including the upper eyelid.

A small lower branch of the lacrimal nerve anastomoses with the zygomatic branch of the zygomatic nerve, which carries secretory fibers for the lacrimal gland.

The second branch of the trigeminal nerve takes part in the sensory innervation of only the auxiliary organs of the eye through its two branches - the zygomatic and infraorbital nerves. Both of these nerves are separated from the main trunk in the pterygopalatine fossa and penetrate into the orbital cavity through the inferior orbital fissure.

The infraorbital nerve, entering the orbit, passes along the groove of its lower wall and goes through the infraorbital canal to the front surface. Innervates central part the lower eyelid, the skin of the wings of the nose and the mucous membrane of its vestibule, as well as the mucous membrane of the upper lip, upper gums, alveolar depressions and, in addition, the upper dentition.

The zygomatic nerve in the cavity of the orbit is divided into two branches: zygomatic and zygomatic. Having passed through the corresponding channels in the zygomatic bone, they innervate the skin of the lateral forehead and a small zone of the zygomatic region.

Types of regional anesthesia in ophthalmic surgery:

Peribulbar block

Retrobulbar block

The most popular technique is currently the peribulbar block. It has largely replaced the retrobulbar block and general anesthesia in many ocular operations.

Training

1. An intravenous cannula is inserted for continuous venous access in case of an emergency.

2. The conjunctival sac is anesthetized with 1% ametocaine. Three drops are injected into each eye, the procedure is repeated three times with an interval of 1 minute.

3. Take a 10 ml syringe with 5 ml of 0.75% bupivacaine mixed with 5 ml of 2% lidocaine with 1: 200,000 adrenaline.

4. Add 75 units of hyaluronidase to improve diffusion of the anesthetic mixture into the orbit, which leads to a faster development of anesthesia and lengthens it.

5. Attach a 25 G needle with a length of 2.5 cm to the syringe.

6. The patient is placed on his back and asked to look straight up at a fixed point on the ceiling so that the eyes are in a neutral position.

Block execution

Two transconjunctival peribulbar injections are usually required.

Lower lateral injection (Fig. 3, 4). The lower eyelid is retracted and the needle is placed midway between the lateral canthus and the lateral limbus. The injection is not painful because is performed through a pre-anesthetic conjunctiva. The needle can also be inserted directly through the skin. The needle advances in the sagittal plane, parallel to the bottom of the orbit, passing under the eyeball. There is no need to apply excessive pressure when doing this. the needle runs freely without any resistance.

When you think that the needle has passed the equator of the eyeball, the direction is changed medially (20 °) and cranially (10 ° up) to avoid the bony border of the orbit. Advance the needle until its taper (i.e. 2.5 cm) is at the level of the iris. After control aspiration, 5 ml of solution is slowly injected. There shouldn't be much resistance. If there is resistance, then the tip of the needle may be in one of the external muscles of the eye and its position should be slightly changed. During the injection, the lower eyelid may fill with anesthetic and some swelling of the conjunctiva may appear.

5 minutes after this injection, some patients develop adequate anesthesia and akinesia, but most require another injection.

Medial injection (Fig. 5). The same needle is inserted through the conjunctiva in the nasal part and is guided straight back parallel to the medial wall of the orbit at a slightly cranial angle of 20 ° until the cone of the needle reaches the iris level. As the needle passes through the dense medial ligament, light pressure may be required, which can cause the eye to be abducted medially for a period of time.

After control aspiration, 5 ml of the specified anesthetic solution is injected. Then the eye is closed and the eyelids are fixed with a plaster. A piece of gauze is placed on top and pressure is provided using a McIntyre oculopressor of 30 mm Hg. If no oculopressor is available, gently apply pressure with the fingers of one hand. This is necessary to reduce intraocular pressure (IOP) by limiting the formation of ocular fluid and increasing its reabsorption.

Usually a block is evaluated 10 minutes after execution.

Signs of a successful block are:

Ptosis (drooping of the eyelid with inability to open the eyes)

Lack of movement or minimal movement of the eyeballs in all directions (akinesia)

pain during injection, sudden loss of vision, hypotension, or hematoma vitreous... Perforation can be avoided by carefully inserting the needle without pointing up and in until the end of the needle passes the equator of the eye.

Central penetration of local aiestetics: This is due to either direct injection under the dura mater, which envelops the optic nerve prior to its connection to the sclera, or during retrograde arterial spread. May occur various symptomsincluding lethargy, vomiting, contralateral blindness due to the effect of the anesthetic on the optic nerve intersection, seizures, respiratory depression, neurological symptoms, and even cardiac arrest. All of these symptoms usually develop within 5 minutes of injection.

Oculocardial reflex is bradycardia that can occur with traction of the eye. An effective block prevents the development of the oculocardiac reflex by interrupting the reflex chain. However, block execution and especially rapid tissue stretching with an anesthetic solution or bleeding can sometimes be accompanied by the development of this reflex. For its timely recognition, appropriate monitoring is necessary.

Optic nerve atrophy. Damage to the optic nerve and vascular retinal occlusion can be caused by direct damage to the optic nerve or the central retinal artery, injection into the optic nerve sheath, or bleeding under the optic nerve sheath. These complications can lead to partial or complete loss of vision.

The advantages of local anesthesia over general anesthesia:

1. Can be performed in a day hospital

2. Causes good akinesia and anesthesia

3. Minimal effect on intraocular pressure

4. Requires a minimum of equipment

Disadvantages:

1. Not suitable for some patients (children, mentally retarded, deaf, not speaking the language of the doctor)

2. The above complications

3. Depends on the skill of the anesthesiologist

4. Not suitable for certain types of surgery (for example, intraocular surgery, dacryocystorhinostomy, etc.)
Eye surgeries can be performed under both local and general anesthesia. In the previous issue of the journal, published in Russian, methods of regional anesthesia were described. This article discusses the principles of general anesthesia in ophthalmic surgery.

General anesthesia in ophthalmic surgery poses many different challenges to the anesthesiologist. Patients are often of old age and are burdened by various concomitant diseases, especially diabetes and arterial hypertension... The drugs used in ophthalmology can affect the course of anesthesia. For example, drugs for the treatment of glaucoma, including the β-blocker timolol or phospholine iodide, which have anticholinesterase properties, can prolong the action of succinylcholine.

The anesthesiologist should be familiar with the factors affecting intraocular pressure (IOP). IOP is the pressure inside the eyeball, which is normally in the range of 10-20 mm Hg. Art. When the surgeon operates on the intraocular ball, for example, removal of cataracts), the control of IOP by the anesthesiologist is very important. An increase in intraocular pressure can worsen the conditions of the operation and lead to the loss of the contents of the eyeball with irreversible consequences. A slight decrease in IOP improves the operating conditions. An increase in IOP is usually caused by external pressure, an increase in the volume of blood in the intraocular vessels, or an increase in the volume of the vitreous body.

9-11-2012, 12:24

Description

The nervous system of the eye is represented by all types of innervation:

sensitive,
sympathetic
and motor.

Before penetrating into the eyeball, the anterior ciliary arteries give off a number of branches that form a marginal looped network around the cornea. The anterior ciliary arteries also give off branches that supply the conjunctiva adjacent to the limbus (anterior conjunctival vessels).

Nasal nerve gives a twig to the ciliary node, other fibers are long ciliary nerves. Without interrupting in the ciliary node, 3-4 ciliary nerves pierce the eyeball around the optic nerve and but reach the suprachoroidal space the ciliary body, where they form a dense plexus. From the latter, nerve branches penetrate the cornea.

In addition to the long ciliary nerves, the eyeball in the same area includes short ciliary nerves, originating from the ciliary node. The ciliary node is a peripheral nerve ganglion and has a size of about 2 mm. It is located in the orbit on the outside of the optic nerve and 8-10 mm from the posterior pole of the eye.

The ganglion, in addition to the nasal fibers, includes parasympathetic fibers from the plexus of the internal carotid artery.

Short ciliary nerves (4-6) entering the eyeball provide all tissues of the eye with sensory, motor and sympathetic fibers.

Sympathetic nerve fibers, innervating the pupil dilator, enter the eye as part of the short ciliary nerves, but, joining them between the ciliary node and the eyeball, do not enter the ciliary node.

In the orbit, sympathetic fibers from the plexus of the internal carotid artery that do not enter the ciliary node are attached to the long and short ciliary nerves. The ciliary nerves enter the eyeball near the optic nerve. Short ciliary nerves coming from the ciliary node in the amount of 4-6, passing through the sclera, increase to 20-30 nerve trunks, which are distributed predominantly in the vascular tract, and there are no sensory nerves in the choroid, and the sympathetic fibers, which have joined the orbit, innervate the iris dilator shell. Therefore, in case of pathological processes in one of the membranes, for example, in the cornea, changes are noted in both the iris and the ciliary body... Thus, the main part of the nerve fibers goes to the eye from the ciliary node, which is located 7-10 mm from the posterior pole of the eyeball and is adjacent to the optic nerve.

The ciliary assembly includes three roots:

sensitive (from the nasal ciliary nerve - branches of the trigeminal nerve);
motor (formed by parasympathetic fibers passing through the oculomotor nerve)
and sympathetic.

From four to six short ciliary nerves emerging from the ciliary node branch out into another 20-30 branches, which are directed along all structures of the eyeball. They are accompanied by sympathetic fibers from the upper cervical sympathetic ganglion, which do not enter the ciliary node, innervating the muscle that dilates the pupil. In addition, 3-4 long ciliary nerves (branches of the nasal ciliary nerve) also pass into the eyeball, bypassing the ciliary node.

Motor and sensory innervation of the eye and its auxiliary organs... The motor innervation of the human organ of vision is realized with the help of the III, IV, VI, VII pairs of cranial nerves, the sensitive one - through the first and partly the second branches of the trigeminal nerve (V pair of cranial nerves).

Oculomotor nerve (the third pair of cranial nerves) begins from the nuclei lying at the bottom of the Sylvian aqueduct at the level of the anterior hillocks of the quadruple. These nuclei are heterogeneous and consist of two main lateral (right and left), including five groups of large cells, and additional small-cell ones - two paired lateral (Yakubovich - Edinger - Westphal nucleus) and one unpaired (Perlia nucleus) located between them. The length of the nuclei of the oculomotor nerve in the anteroposterior direction is 5 mm.

From the paired lateral large cell nuclei, there are fibers for three straight (upper, inner and lower) and lower oblique oculomotor muscles, as well as for two days of portions of the muscle that lifts the upper eyelid, and the fibers innervating the inner and lower straight lines, as well as the lower oblique muscles, immediately do overlap.

Fibers extending from paired small-cell nuclei through the ciliary node innervate the sphincter muscle of the pupil, and those extending from the unpaired nucleus - the ciliary muscle. Through the fibers of the medial longitudinal bundle, the nuclei of the oculomotor nerve are connected with the nuclei of the trochlear and abducens nerves, the system of the vestibular and auditory nuclei, the nucleus of the facial nerve and the anterior horns of the spinal cord. Thereby the reactions of the eyeball, head, trunk to all kinds of impulses are provided, in particular vestibular, auditory and visual.

Through the superior orbital fissure, the oculomotor nerve enters the orbit, where, within the muscular funnel, it is divided into two branches - upper and lower. Upper thin branch is located between the upper muscle and the muscle that lifts the upper eyelid, and innervates them. Lower, larger, branch passes under the optic nerve and is divided into three branches - the outer (from it the root departs to the ciliary node and the fibers for the lower oblique muscle), the middle and internal (the lower and internal rectus muscles are innervated, respectively). The root carries fibers from the accessory nuclei of the oculomotor nerve. They innervate the ciliary muscle and the sphincter of the pupil.

Block nerve (the fourth pair of cranial nerves) starts from the motor nucleus (length 1.5-2 mm), located at the bottom of the Sylvian aqueduct immediately behind the nucleus of the oculomotor nerve. Penetrates into the orbit through the superior orbital fissure lateral to the muscle funnel. It innervates the superior oblique muscle.

Abducens nerve (the sixth pair of cranial nerves) starts from the nucleus located in the pons of varoli at the bottom of the rhomboid fossa. It leaves the cranial cavity through the superior orbital fissure, located inside the muscle funnel between the two branches of the oculomotor nerve. It innervates the external rectus muscle of the eye.

Facial nerve (the seventh pair of cranial nerves) has a mixed composition, that is, it includes not only motor, but also sensory, taste and secretory fibers that belong to the intermediate nerve. The latter is closely adjacent to the facial nerve at the base of the brain from the outside and is its posterior root.

The motor nucleus of the nerve (length 2-6 mm) is also located in the lower part of the pons varoli at the bottom of the fourth ventricle. The fibers departing from it come out in the form of a root to the base of the brain in the cerebellopontine angle. Then the facial nerve with an intermediate one enters the facial canal of the temporal bone. Here they merge into a common trunk, which further penetrates the parotid salivary gland and divides into two branches that form the parotid plexus. From it to the facial muscles, the nerve trunks extend, including the circular muscle of the eye.

Intermediate nerve contains secretory fibers for the lacrimal gland, located in the brain stem, and through the knee node they enter the large petrosal nerve. The afferent pathway for the main and accessory lacrimal glands begins with the conjunctival and nasal branches of the trigeminal nerve. There are other zones of reflex stimulation of tear production - the retina, anterior frontal lobe of the brain, basal ganglion, thalamus, hypothalamus, and cervical sympathetic ganglion.

The level of damage to the facial nerve can be determined by the state of secretion of tear fluid. When it is not broken, the focus is below the knee node, and vice versa.

Trigeminal nerve (the fifth pair of cranial nerves) is mixed, that is, it contains sensory, motor, parasympathetic and sympathetic fibers. It contains nuclei (three sensitive - spinal, bridge, midbrain - and one motor), sensory and motor roots, as well as the trigeminal node (on the sensitive root).

Sensory nerve fibers start from the bipolar cells of a powerful trigeminal ganglion, 14-29 mm wide and 5-10 mm long.

The trigeminal axons form the three main branches of the trigeminal nerve. Each of them is associated with certain nerve nodes:

the optic nerve - with the ciliary,
maxillary - with pterygopalatine
and the mandibular - with the auricular, submandibular and sublingual.

The first branch of the trigeminal nerve, being the thinnest (2-3 mm), leaves the cranial cavity through the orbital fissure. When approaching it, the nerve is divided into three main branches: n. nasociliaris, n. frontalis, n. lacrimalis.

Nasociliary nerve, located within the muscle funnel of the orbit, in turn, is divided into long ciliary ethmoid and nasal branches and, in addition, gives the root to the ciliary node.

Long ciliary nerves in the form of 3-4 thin trunks are directed to the posterior pole of the eye, perforate the sclera in the circumference of the optic nerve and along the suprachoroidal space are directed anteriorly along with short ciliary nerves extending from the ciliary body and along the circumference of the cornea. The branches of these plexuses provide sensory and trophic innervation the corresponding structures of the eye and perilimbal conjunctiva. The rest of it receives sensitive innervation from the palpebral branches of the trigeminal nerve.

On the way to the eye, sympathetic nerve fibers from the plexus of the internal carotid artery are attached to the long ciliary nerves, which innervate the pupil dilator.

Short ciliary nerves (4-6) depart from the ciliary node, the cells of which are connected with the fibers of the corresponding nerves through the sensory, motor and sympathetic roots. It is located at a distance of 18-20 mm behind the posterior pole of the eye under the external rectus muscle, adjacent in this zone to the surface of the optic nerve.

Like the long ciliary nerves, the short ones also approach the posterior pole of the eye, perforate the sclera along the circumference of the optic nerve and, increasing in number (up to 20-30), participate in the innervation of the eye tissues, primarily its choroid.

The long and short ciliary nerves are the source of sensory (cornea, iris, ciliary body), vasomotor and trophic innervation.

The terminal branch of the nerve nasociliaris is subblock nerve, which innervates the skin in the area of \u200b\u200bthe root of the nose, the inner corner of the eyelids and the corresponding parts of the conjunctiva.

Frontal nerve, being the largest branch of the optic nerve, after entering the orbit, it gives off two large branches - the supraorbital nerve with medial and lateral branches and the supra-block nerve. The first of them, having perforated the tarzoorbital fascia, passes through the nasopharyngeal opening of the frontal bone to the skin of the forehead, and the second comes out of the orbit at its internal ligament. In general, the frontal nerve provides sensory innervation to the midsection of the upper eyelid, including the conjunctiva, and to the forehead.

Lacrimal nerve, entering the orbit, goes anteriorly over the external rectus muscle of the eye and is divided into two branches - the upper (larger) and lower. The upper branch, being a continuation of the main nerve, gives off branches to the lacrimal gland and conjunctiva. Some of them, after passing through the gland, perforate the tarzoorbital fascia and innervate the skin in the outer corner of the eye, including the upper eyelid. A small lower branch of the lacrimal nerve anastomoses with the zygomatic branch of the zygomatic nerve, which carries secretory fibers for the lacrimal gland.

Infraorbital nervehaving entered the orbit, it passes along the groove of its lower wall and through the infraorbital canal goes to the front surface. It innervates the central part of the lower eyelid, the skin of the wings of the nose and the mucous membrane of its vestibule, as well as the mucous membrane of the upper lip, upper gum, alveolar depressions and, in addition, the upper dentition.

Zygomatic nerve in the cavity of the orbit is divided into two branches: zygomatic and zygomatic. Having passed through the corresponding channels in the zygomatic bone, they innervate the skin of the lateral forehead and a small zone of the zygomatic region.

17-09-2011, 13:32

Description

The lacrimal nerve innervates the lacrimal gland, the outer conjunctiva of the eyelids and eyeball, the skin of the lower and upper eyelids.

The nasal nerve gives off a branch to the ciliary node, 3-4 long ciliary branches go to the eyeball, in the suprachoroidal space near the ciliary body they form a dense plexus, the branches of which penetrate into the cornea. At the edge of the cornea, they enter the middle sections of its own substance, while losing their myelin coating. Here, the nerves form the main corneal plexus. Its branches under the anterior boundary plate (Bowman's) form one plexus of the "closing chain" type. The stems coming from here, piercing the border plate, fold on its front surface into the so-called subepithelial plexus, from which branches extend, ending with end sensitive devices directly in the epithelium.

The frontal nerve is divided into two branches: the supraorbital and supra-block. All the branches, anastomosing with each other, innervate the middle and inner part of the upper eyelid skin.

The oculomotor nerve innervates all the rectus muscles except the external one, as well as the lower oblique, which lifts the upper eyelid, the sphincter of the pupil and the ciliary muscle.

The blocky nerve innervates the superior oblique muscle, the abducens nerve - the external rectus muscle.

The circular muscle of the eye is innervated by a branch of the facial nerve.

Accessory apparatus of the eye

The accessory apparatus of the eye includes the eyelids, conjunctiva, lacrimal and lacrimal organs, retrobulbar tissue.

Eyelids (palpebrae)

The main function of the eyelids is protective. The eyelids are a complex anatomical formation that includes two sheets - musculocutaneous and conjunctival cartilage.

The circular muscle of the eye consists of palpebral and orbital bundles. The fibers of both bundles start from the inner ligament of the eyelids - a powerful fibrous horizontal cord, which is the formation of the periosteum of the frontal process of the upper jaw. The fibers of the palpebral and orbital parts are in arcuate rows. The fibers of the orbital part in the area of \u200b\u200bthe outer corner pass to the other eyelid and form a full circle. The circular muscle is innervated by the facial nerve.

In the thickness of the cartilage, perpendicular to the edge of the eyelids, there are modified sebaceous glands - meibomian glands. Their excretory ducts enter the intermarginal space and are located along the posterior rib of the eyelids. The secret of the meibomian glands prevents tears from flowing through the edges of the eyelids, forms a lacrimal stream and directs it into the lacrimal lake, protects the skin from maceration, and is part of the precorneal film that protects the cornea from drying out.

The blood supply to the eyelids is carried out from the temporal side by branches from the lacrimal artery, and from the nasal side from the ethmoid. Both are the terminal branches of the orbital artery. The largest accumulation of eyelid vessels is located 2 mm from its edge. This must be taken into account during surgical interventions and injuries, as well as the location of the muscle bundles of the eyelids. Given the high displacement capacity of the eyelid tissues, it is desirable to minimize the removal of damaged areas during the initial surgical treatment.

The regional lymph node of the upper eyelid is the anterior lymph node, and the lower one is the submandibular. This must be taken into account when spreading infection and metastasizing tumors.

Conjunctiva

The conjunctiva forms a slit-like cavity (sac) between the eyelid and the eye, which contains the capillary layer of the tear fluid.

There are 3 divisions of the conjunctiva: the conjunctiva of the eyelids, the conjunctiva of the arches (upper and lower) and the conjunctiva of the eyeball.

In the conjunctiva of the eyeball, the adenoid apparatus of the deep layer is poorly represented, it is completely absent in the corneal region. The stratified squamous epithelium of the conjunctiva of the eyeball is non-keratinizing and retains this property under normal physiological conditions. The conjunctiva of the eyeball is much more abundant than the conjunctiva of the eyelids and arches, it is equipped with sensitive nerve endings (the first and second branches of the trigeminal nerve). In this regard, even small foreign bodies or chemicals getting into the conjunctival sac causes a very unpleasant sensation. It is more significant in conjunctival inflammation.

The vascular system of the conjunctiva is part of the general circulatory system of the eyelids and eyes. The main vascular distributions are located in its deep layer and are represented mainly by the links of the microcircular network. The many intramural blood vessels of the conjunctiva provide the vital activity of all its structural components.

Lacrimal organs

The lacrimal organs consist of two separate topographically different departments, namely the lacrimal and the lacrimal. The tear performs protective (washes out foreign elements from the conjunctival sac), trophic (nourishes the cornea that does not have its own vessels), bactericidal (contains nonspecific factors of immune defense - lysozyme, albumin, lactoferin, b-lysine, interferon), moisturizing function (especially the cornea , maintaining its transparency and being part of the precorneal film).

Tear-producing organs.

3-5 excretory ducts of the orbital part of the lacrimal gland pass through the substance of the lower lacrimal gland, receiving part of its excretory ducts.

With various emotional manifestations, the lacrimal glands, receiving additional nerve impulses, produce excess fluid, which drains from the eyelids in the form of tears. There are persistent disorders of lacrimation in the direction of hyper- or, conversely, hyposecretion, which is often a consequence of the pathology of nerve conduction or excitability. So, lacrimation decreases with paralysis of the facial nerve (VII pair), especially with damage to its geniculate node; paralysis of the trigeminal nerve (V pair), as well as some poisoning and severe infectious diseases with high fever. Chemical, painful temperature irritations of the first and second branches of the trigeminal nerve or zones of its innervation - the conjunctiva, the anterior parts of the eye, the mucous membrane of the nasal cavity, the dura mater are accompanied by profuse lacrimation.

Lacrimal ducts.

The end sections of the lacrimal canals, each individually or merging with each other, open into the upper section of a wider reservoir - the lacrimal sac. The mouth of the lacrimal tubules usually lie at the level of the medial commissure of the eyelids.

What nerves innervate the smooth muscles of the eye. Oculomotor muscles

Description

Accessory apparatus of the eye

Description

Description

Accessory apparatus of the eye

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