Internal rectus muscle of the eye. Oculomotor muscles and their disorders

The movements of each eyeball are provided by the reduction of six striated (external, extraocular) eye muscles. These include the lateral, medial, superior and inferior rectus muscles (respectively m. rectus lateralis, m. rectus me-dialis, m. rectus superior, m. rectus inferior) and superior and inferior oblique muscles (m. obliquus superior, etc.). obliquus inferior).

All rectus and superior oblique muscles begin in the depths of the orbit from a common tendon ring covering the optic nerve and ophthalmic artery (a. ophtalmica), pass along the walls of the orbit, penetrate the vagina of the eyeball and penetrate the sclera. The rectus muscles, with the help of tendons fused with the sclera, are attached to the four sides of the eyeball in front of its equator. The superior oblique muscle is thrown over the cartilaginous ring of the block (trochlea), which is attached to the block fossa (fovea trochlearis) or block protrusion (spina trochlearis) on the lower surface of the orbital part of the frontal bone at the border of the upper and inner walls of the orbit. The superior rectus then turns sharply backward and sideways, passes under the superior rectus, and attaches to the sclera on the superolateral surface of the eyeball behind the equator (Fig. 1.1).

M. rectus inferior M. obliquus inferior

Rice. 1.1. External muscles of the eye, a - view of the orbit from above; b - side view of the orbit

The inferior oblique muscle originates from the orbital surface of the maxillary bone, lateral to the fossa of the lacrimal sac, goes laterally, backwards and upwards under the eyeball between the inferior rectus muscle and the inferior wall of the orbit, and is attached by a tendon to the sclera on the lateral surface of the eyeball behind the equator between the inferior rectus and lateral rectus muscles. The inferior oblique tendon, located under the eyeball, is parallel to the superior oblique tendon, located above the eyeball (see Fig. 1.1).

The eyeball is held in the orbit by a connective tissue bag (Tenon's capsule) attached to the walls of the orbit by ligaments, and can freely rotate in all directions around three axes: vertical, horizontal and sagittal.

It should be taken into account that the optical axes and the axes of the orbits do not coincide (Fig. 1.2), so the result of contraction of the external muscles of the eye depends on the initial position of the eye. Fig. Figure 1.3 demonstrates the different effects of contraction of the superior rectus muscle that occur with different initial positions of the eye in the orbit.

Rice. 1.3.

eyes (right eyeball)

A- starting position: the eye looks straight ahead. Eye movement during muscle contraction: lifting, adduction, intarsia; b - starting position: the eye is retracted. Eye movement during muscle contraction: lifting; V- starting position: the eye is brought.

Eye movement during muscle contraction: intarsia and slight elevation

In general, the main action of the upper and lower rectus muscles is the rotation of the eyeball around the transverse axis, moving it up or down, respectively. At the same time, the eye makes small movements around the vertical and sagittal axes.

The lateral and medial rectus muscles rotate the eyeball around the vertical axis, directing it to the lateral or medial side, respectively. The oblique muscles rotate the eyeball mainly around the sagittal axis, although they also cause movements around the other two axes of space (Fig. 1.4). So, the right upper oblique muscle normally rotates the right eye around the sagittal axis clockwise (toward the nose), lowers and abducts it. The right inferior oblique muscle rotates the right eyeball around the sagittal axis counterclockwise (away from the nose), lifts and retracts it.

a B C Where

Rice. 1.4. The action of the external muscles of the eye relative to the three axes of space A- m. rectus inferior, b - t. rectus superior, V- t. rectus medialis, r- t. rectus lateralis, d - t. obliquus superior, e - t. obliquus inferior

In general terms, the direction of gaze provided by the contraction of various external muscles of the eye is shown in Fig. 1.5.

Rice. 1.5. Direction of action of the external muscles of the eye (according to Lindsay K.W., Bone J.R., 2004)

The muscles of the eye perform coordinated movements of the eyeballs, providing high-quality and volumetric vision.

There are only six oculomotor muscles in the eye, of which four are straight and two are oblique, which received this name because of the peculiarities of the muscle in the orbit and attachment to the eyeball. Muscle function is controlled by three cranial nerves: oculomotor, abducens, and trochlear. Each muscle fiber of this muscle group is richly supplied with nerve endings, which ensures special clarity and accuracy in movements.

Thanks to the oculomotor muscles, numerous options for the movement of the eyeballs are possible, both unidirectional: up, to the right, and so on; and multidirectional, for example, reducing the eyes when working at close range. The essence of such movements is that, due to the coordinated work of the muscles, the same image of objects falls on the same parts of the retina - the macular area, providing good vision and a sense of depth.

Features of the structure of the muscles of the eye

There are 6 oculomotor muscles, of which 4 are straight, going in the forward direction: internal, external, upper and lower. The remaining 2 are called oblique, as they have an oblique direction of travel and attachment to the eyeball - the upper and lower oblique muscles.

All muscles, with the exception of the inferior oblique, start from a dense connective tissue ring surrounding the external opening of the optic canal. Anterior to its origin, 5 muscles form a muscular funnel, inside which the optic nerve, blood vessels, and nerves pass. Further, the superior oblique muscle gradually deviates upward and inwards, following to the so-called block. At this point, the muscle passes into the tendon, which is thrown over the loop of the block and changes its direction to oblique, attaching in the upper outer quadrant of the eyeball under the superior rectus muscle. The inferior oblique muscle originates at the inferior inner edge of the orbit, runs outward and posteriorly under the inferior rectus muscle, and inserts in the inferior outer quadrant of the eyeball.

Approaching the eyeball, the muscles are surrounded by a dense capsule - Tenon's membrane and join the sclera at different distances from the limbus. Closest of all of the rectus muscles to the limbus, the internal is attached, and then the upper rectus, while the oblique muscles are attached to the eyeball slightly posterior to the equator, that is, the middle of the length of the eyeball.

The work of the muscles is regulated, for the most part, by the oculomotor nerve: the superior, internal, inferior rectus and inferior oblique muscles, with the exception of the external rectus muscle, the work of which is provided by the abducens nerve and the superior oblique - the trochlear nerve. A feature of nervous regulation is that one branch of the motor nerve controls the work of a very small number muscle fibers, due to which maximum accuracy is achieved when moving the eyes.

The movements of the eyeball depend on the features of muscle attachment. The places of attachment of the internal and external rectus muscles coincide with the horizontal plane of the eyeball, due to this, it is possible horizontal movements eyes: turn to the nose with the contraction of the internal rectus and to the temple with the contraction of the external rectus muscle.

The upper and lower rectus muscles mainly provide vertical eye movements, but since the line of attachment of the muscles is located somewhat obliquely with respect to the limbus line, simultaneously with the vertical movement, the eye also moves inwards.

The oblique muscles during contraction cause more complex actions, this is due to the peculiarities of the location of the muscles and their attachment to the sclera. The superior oblique muscle lowers the eye and turns outward, while the inferior oblique muscle raises it and also withdraws it outward.

In addition, the superior and inferior rectus muscles, as well as the oblique muscles, provide small turns of the eyeball clockwise and counterclockwise. Due to good nervous regulation and well-coordinated work of the muscles of the eyeball, complex movements are possible, both unilateral and directed to different sides, due to which there is a three-dimensionality of vision, or binocularity, and, in addition, the quality of vision increases.

Diagnostic methods

• Determination of eye mobility - the completeness of eye movements is assessed when tracking a moving object.
• Strabometry - assessment of the angle or degree of deviation of the eyeball from the midline in strabismus.
• Cover test - alternately cover one and the second eye to determine latent strabismus - heterophoria, and in case of obvious strabismus, its type is determined.
• Ultrasound diagnostics - determination of changes in the oculomotor muscles in close proximity to the eyeball.
• Computed tomography, magnetic resonance imaging - detection of changes in the oculomotor muscles throughout their length.

Disease symptoms

• Double vision is possible with obvious strabismus and with pronounced latent strabismus.
• Nystagmus - occurs when the ability of the eyes to fix objects is impaired.

7-06-2012, 14:35

Description

The muscular apparatus of the eye is represented by 6 muscles: four straight lines - upper, lower, medial, lateral and two oblique - upper and lower. The place of origin of all the listed extraocular muscles, except for the inferior oblique, is the top of the orbit, where the muscles, merging, form a dense tendon ring located around the optic opening and the medial part of the superior orbital fissure. All rectus muscles in the form of flat wide belts are directed anteriorly, to the place of their attachment. Gradually diverging, all four rectus muscles of the eye form the so-called muscular funnel. The concept of the muscular funnel plays an important role in the topography of the orbit and in the differential diagnosis of pathological processes in the orbit, especially tumors, which give different symptoms and a different prognosis depending on the localization inside the funnel or outside it (Figure 2).

Figure 2.
The location of the external muscles of the eye in the orbit. Muscle funnel. The optic nerve passes between the diverging muscles along the axis of the muscle funnel. 1 - tendon ring of Zinn (annulus tendineus communis Zinnii); 2 - m. obliquus superior; 3 - the place of its passage through the block; 4 - m. rectus superior; 5 - m. obliquus inferior; 6 - m. rectus lateralis; 7 - m. rectus inferior; 8 - m. rectus medialis (no Beninghoff, 1957).

Perforating the Tenon's capsule at the level of the equator of the eye, the muscles are attached to the eyeball by wide tendons woven into the sclera.

Superior oblique muscle begins, like the rectus muscles of the eye, in the depths of the orbit, but outside the zinn ring, in the immediate vicinity of it, goes along the superomedial wall of the orbit, to the spina trochlearis. The muscle looks like a round cord. Passing through the block, it sharply narrows, upon exiting the block, it thickens again and turns posteriorly outward. Passing between the eyeball and the superior rectus muscle, it attaches behind the equator in the upper outer quadrant.

Inferior oblique muscle originates separately from all other muscles, from the inner bone wall of the orbit, goes downwards outward, encircling the eyeball between the lower wall of the orbit and the lower rectus muscle, rises upward and attaches to the sclera behind the equator in the same outer quadrant as the upper one.

According to their function, the muscles of the eyeball are divided into three pairs of antagonists, acting in exactly opposite directions:

- medial and lateral straight lines- turn the eye inward and outward;

- top and bottom straight- raise and lower the eyeball;

- oblique muscles- convey rotational movements to the eye.

However only the external and internal rectus muscles are pure antagonists, they rotate the eye in the horizontal plane, regardless of the initial position of the eyeball. The remaining muscles act as pure antagonists only in the abduction position, when the axis of the orbit and the anatomical axis of the eye coincide. With the direct direction of gaze, when the anatomical axis of the orbit and the axis of the eye are at an angle of 25 - 27 degrees, the actions of the muscles are more complex:

- inferior rectus lowers the eyeball down, leads it, tilts its vertical meridian outward.

- superior rectus raises the eyeball up, leads it, tilts the vertical axis of the eye inwards.

- inferior oblique muscle raises the eye up, takes it away, tilts the vertical meridian outward.

- superior oblique muscle lowers the eyeball downwards, abducts it, tilts the vertical axis of the eye inwards.

In addition, the tone of the rectus muscles of the eye tends to pull the eyeball posteriorly, and the two oblique muscles anteriorly.

Thus, all muscular system eyes is in very fine balance.

Upper and lower eyelids protect the eyeball from the front and due to their blinking movements, which contribute to the uniform distribution of tears, they protect it from drying out.

The eyelids regulate the amount of light entering the eye.. Reflex closure of the eyelids occurs in response to mechanical, visual or
sound stimuli. The upward reflex movement of the eye (Bell's phenomenon) during closure of the eyelids protects the cornea from the ingress of foreign bodies and the drying of the cornea during sleep.

The edges of the eyelids form palpebral fissure(rima palpebrarum). (Figure 3).

Figure 3. Eyelid structure.
Sagittal section through both eyelids, conjunctival sac and anterior eyeball.
1 - supreorbital edge of the frontal bone; 2 - orbital fat; 3 - levator musculus palpebrae superior; bundles of its tendon fibers penetrate from the left through the circular muscle of the eyelids into the skin; 4 - tendon m. rectus superior. Eyeball: 5 - sclera; 6 - conjunctiva of the upper fornix - upper transitional fold; 7 - cornea; 8 - conjunctiva of the lower fornix; 9 - tendon m. rectus inferior; 10 - section of the inferior oblique muscle; 11 - lower orbital edge of the upper jawbone; 12 - orbital fat; 13 - tarsoorbital fascia - septum orbitale; 14 - cartilage of the lower eyelid; 15 - conjunctiva of the cartilage of the lower eyelid; 16 - conjunctiva of the cartilage of the upper eyelid; 17 - cartilage of the upper eyelid; 18 - m. orbicularis palpebrarum (according to M. L. Krasnov, 1952).

The border of the upper eyelid runs along the eyebrow, the lower eyelid along the lower edge of the orbit. Both eyelids are connected at the corners of the palpebral fissure by the internal and external ligaments (l.palpebrale mediale et laterale). The width and shape of the palpebral fissure varies normally: its horizontal length in an adult is 30 mm, its height varies from 10 to 14 mm, the edge of the lower eyelid does not reach the limbus 0.5-1 mm, the edge of the upper eyelid covers the limbus by 2 mm. The outer edge of the palpebral fissure is sharp, the inner edge is blunted in the form of a horseshoe-shaped bend. The latter limits the space called the lacrimal lake, in which the lacrimal caruncle (caruncula lacrimalis) is located - a small pink tubercle that has a skin structure with sebaceous and sweat glands, and a semilunar fold (plica semilunaris) of a thickened mucous membrane, which are vestiges of the third century. The free edges of the eyelids, about 2 mm thick, fit snugly against each other. They distinguish between anterior, posterior ribs and intermarginal space. On the front, more rounded rib, eyelashes grow (75-150 pieces), into the bulbs of which the excretory ducts of Zeiss's sebaceous glands open. Between the eyelashes are modified Moll's sweat glands. The excretory ducts of the meibomian glands open into the intermarginal space, the fatty secretion of which lubricates the edges of the eyelids, contributing to their sealing. At the inner corner of the eye, i.e. near the lacrimal lake, the intermarginal space narrows and passes into lacrimal papillae(papilli lacrimales). At the top of each of them is the lacrimal opening - an opening leading to the lacrimal canaliculus. The diameter of the lacrimal opening with open eyelids is 0.25 - 0.5 mm. The eyelids consist of 2 plates: the outer plate is formed by skin with muscles, the inner one is cartilage (tarsus) and the cartilage conjunctiva tightly fused with it.

Eyelid skin is very thin, tender, poor in fatty tissue, loosely connected to the underlying tissues. On the skin surface of the upper eyelid there is a deep orbito-palpebral upper, on the lower - orbito-palpebral lower folds. The first is located just below the upper orbital edge and is due to the tone of the anterior leg of the levator attached to the posterior surface of the skin. The thinness and slight displacement of the skin of the eyelids relative to the underlying tissues are good conditions to perform plastic surgery. But in this regard, the skin easily swells with local inflammation, venous congestion, a number of common diseases, hemorrhages and subcutaneous emphysema.

The mobility of the eyelids is provided by two groups of antagonist muscles: circular muscle th eyes and ve lifters to (m. levator palpebrae superior and m. tarsalis inferior).

Circular muscle of the eyelid- m. orbicularis oculi, s. palpebrarum, in which the palpebral, orbital and lacrimal parts are distinguished. The orbicular muscle is involved in lowering the upper eyelid and closing the palpebral fissure. The palpebral part is located within the eyelids themselves and does not go beyond their edges. Muscle fibers, both on the upper and on lower eyelids are woven into a dense medial ligament. Describing a semicircle along each eyelid, they are temporally attached to the outer commissure (lateral ligament) of the eyelids. Thus, they form two crescents in each eyelid. With the contraction of the palpebral part, blinking and slight closing of the eyelids occurs, as in a dream. The muscle fibers running along the edge of the eyelids between the roots of the eyelashes and the excretory ducts of the meibomian glands make up the ciliary muscle, or the Riolan muscle (m.ciliaris Riolani), the contraction of which contributes to the secretion of the meibomian glands, as well as a tight fit of the edges of the eyelids to the eyeball. Orbital: fibers originate from the medial ligament and from the frontal segment of the maxilla and run along the periphery of the palpebral part of the orbicularis muscle. The muscle has view of a wide layer extending beyond the edges of the orbit and connects with mimic muscles faces. Having described a full circle, the muscle is attached near the place of its beginning. With the contraction of this muscle, together with the contraction of the palpebral part, tight closing of the eyelids is carried out.

Lacrimal part of the orbicular muscle of the eye(Horner's muscle) is represented by a deep portion of muscle fibers that begin somewhat posterior to the posterior crest of the lacrimal bone (crista lacrimalis posterior os lacrimale). Then they pass behind the lacrimal sac and are woven into the palpebral fibers of the orbicularis muscle, coming from the anterior lacrimal crest. As a result, the lacrimal sac is covered by a muscle loop, which, when contracting and relaxing during blinking movements, either expands or narrows the lumen of the lacrimal sac. Absorption and promotion of the lacrimal fluid along the lacrimal ducts is also facilitated by the contraction of those bundles of the lacrimal muscle that cover the lacrimal canaliculi.

In raising the upper eyelid and opening the palpebral fissure involved striated- m.levator palpebrae superior and smooth muscle- superior and inferior tarsal or Müllerian muscles. There is no muscle similar to the levator on the lower eyelid. The function of raising the lower eyelid is carried out by a weakly expressed muscle (m. tarsalis inferior) and the lower rectus muscle of the eye, which gives an additional tendon to the thickness of the lower eyelid.

M. levator palpebrae superior - starts in the depth of the orbit, where at the top it departs from the tendon ring (annulus tendineus communis) together with the rectus muscles of the eyeball, goes under the roof of the orbit anteriorly and at the level of the supraorbital edge passes into a wide tendon, which diverge fan-shaped and divide into three departments. The anterior part of the tendon in the form of thin bundles of fibers passes the tarsoorbital fascia and the orbicular muscle, diverges fan-shaped and merges with the subepithelial layer of the skin of the eyelids. back portion penetrates into the upper fornix of the conjunctiva and is attached here. Medium - the most powerful(Muller's muscle) is attached along the upper edge of the cartilage throughout its continuation. In its structure, the Müller muscle is reticulate, only part of its muscle bundles comes perpendicular to the edge of the cartilage, penetrating between the levator fibers and accompanying them in places to the upper edge of the cartilage. In this case, the levator tendon is stratified by smooth muscle fibers. The other part of the fibers approaches in an oblique direction. The third forms a well-defined transverse beam, weaving into the aponeurosis of the levator. Such contact with the levator aponeurosis provides not only elevation, but also prevents wrinkling of the eyelid. The lateral branches of the levator tendon fix it to the periorbit. Contraction of the muscle leads to pulling up simultaneously the skin, tarsal plate and conjunctival fornix. The main muscle is the muscle that lifts the upper eyelid, the auxiliary muscle of Müller lying under it, and when looking up, the frontal and superior rectus. The Muller muscle is innervated by the sympathetic nerve, and the remaining two portions are innervated by the III pair (oculomotor nerve).

With the contraction of the palpebral part of the circular muscle of the eye blinking and slight squeezing of the eyelids. It was established by electromyography that during voluntary blinking movements, the muscle, levator levator lid and orbicularis muscle act reciprocally: the activity of one is accompanied by the passivity of the other. If the upper eyelid slowly descends, then not only the activity of the muscle that lifts it decreases, but the antagonist (circular muscle) also remains passive. However, the general mechanism of closing the eyelids is more complicated due to the combined connection of the orbicular muscle with the mimic muscles on the one hand and the epidermis of the facial skin on the other. As a result of these connections, the eyelids, when closed, move not only up and down, but also in a horizontal direction - inwards, especially the lower one, which plays an important role in the advancement of the lacrimal fluid. When the eyelids close, the palpebral fissure shortens by 2 mm. In addition, the deep part of the palpebral portion of the circular muscle plays a leading role in the mechanism of lacrimal evacuation.

Ligaments of the eyelids

medial and lateral ligaments serve as the main apparatus that attaches various elements of the eyelid to the bone wall of the orbit: the edges of the eyelids themselves, the circular muscle of the eye, the edges of the cartilage and the tarsoorbital fascia. The medial ligament has two legs: front and back. The first in the form of a powerful collagen cord formed by the tendon of the orbicular muscle and merging with it by the collagen fibers of the medial sections of the cartilage and the orbicular fascia, runs in the horizontal direction in front of the lacrimal sac from the inner corner of the eyelids to the anterior lacrimal scallop (upper jaw). The cord is well palpable and becomes visible when the conjunctiva is pulled down, due to the tension of the internal ligament. Its back leg branches slightly away from the angle of the eyelids in the form of a tendon, bends around the lacrimal sac outside and behind and is attached to the posterior lacrimal crest of the lacrimal bone. Thus, the medial ligament covers the lacrimal sac both anteriorly and posteriorly. The lateral ligament of the eyelids, in comparison with the internal one, is poorly developed and is only a suture with a tendon bridge between the outer parts of the orbicular muscle of the upper and lower eyelids. The ligament is reinforced by the collagen fibers woven into it from the outer ends of the cartilage and the tarsoorbital fascia. It also runs horizontally from the outer corner of the eyelids to the bony tubercle of the zygomatic bone - tuberculum orbitae, where it is attached 2-3 mm away from the edge of the orbit.

Cartilage of the eyelid

It is a crescent-shaped plate with pointed edges (during incision in the intermarginal space, it easily splits into 2 plates). The collagen tissue that forms this plate with an admixture of elastic fibers is distinguished by a special cartilaginous density. Therefore, the name cartilage has taken root, although histologically, there are no elements of cartilage here. The pointed ends of the cartilages are firmly connected to each other by a binding of collagen fibers. Collagen fibers running from the edges of the cartilage to the medial and lateral ligaments of the eyelids fix the cartilage to the bony walls of the orbit. The density of cartilage determines its protective “skeletal” function. Cartilage repeats the convex shape of the eyeball. The length of the cartilage of the upper eyelid is 2 cm, the height is 1 cm, the thickness is 1 mm, the cartilage of the lower eyelid is smaller, its height is 5 mm. The anterior surface borders on loose connective tissue, the posterior one is closely connected with the conjunctiva.

In the thickness of the cartilage, modified sebaceous glands - meibomian(on the upper eyelid - 27-30, on the lower - about 20). They have an alveolar structure and secrete a fatty secret. Very short ducts of the alveoli flow into a long common excretory duct. The glands are parallel to each other and perpendicular to the free edge of the eyelids, occupying the entire height of the cartilage. The openings of the ducts open in front of the posterior rib of the eyelid in the form of pores. The secret of the meibomian glands serves as a fatty lubricant, protects the edges of the eyelids from maceration, prevents the transfusion of tears over the edge of the eyelids, contributing to its proper outflow.

Thus, the cartilage is like direct continuation of the tarsoorbital fascia, strongly associated with the orbital edge. This septum (septum orbitae) completely separates the contents of the orbit from the tissues of the eyelids, preventing the spread of pathological processes in depth. The back surface of the eyelids is covered with conjunctiva, which is tightly fused with cartilage, and outside it forms mobile vaults. Deep upper vault and shallower and easily accessible lower vault.

The conjunctiva is a thin, transparent mucous tissue, which in the form of a thin shell covers the entire rear surface eyelid (tunica conjunctiva palpebrarum), forms deep arches (fornix conjunctivae superior et inferior) and passes to the eyeball (tunica conjunctiva bulbi) ending at the limbus. In the conjunctiva of the eyelids, in turn, they distinguish the tarsal part - tightly fused with the underlying tissue, and the mobile - orbital, in the form of a fold transitional to the arches.

cartilage conjunctiva covered with a two-layer cylindrical epithelium and contains goblet cells at the edge of the eyelids, and the crypts of Henle at the distal end of the cartilage. Both those and others secrete mucin. Under the epithelium is the reticular tissue tightly soldered to the cartilage. At the free edge of the eyelids, the mucous membrane is smooth, but already 2-3 mm from it, roughness appears, due to the presence of papillae here.

Conjunctiva of transitional fold smooth and covered with 5-6 layer transitional epithelium, also with a large number of mucin-secreting goblet cells. Under the epithelium is loose connective tissue, consisting of elastic fibers and containing plasma cells and lymphocytes. The conjunctiva here is easily displaced and forms folds that facilitate the free movements of the eyeball.

On the border between the tarsal and orbital parts in the conjunctiva are additional lacrimal glands s, similar to the structure and function of the main lacrimal gland: Wolfring - 3 at the upper edge of the upper cartilage and one more below the lower cartilage, and in the area of ​​\u200b\u200bthe arches - Krause. The number of the latter reaches 6-8 on the lower eyelid and from 15 to 40 on the upper one. The blood circulation of the eyelids is carried out by two systems: the system of the internal carotid artery (branches of a. ophthalmica). a.supraorbitalis, a.lacrimalis and the system of the external carotid artery (anastomoses a.facialis and a.maxillaris, a.temporales superfacialis).

From the nasal side, they penetrate into the thickness of both eyelids from the depth of the orbit medial palpebral arteries of the eyelid- upper and lower (a. palpebralis mediales superiores et inferiores) - terminal branches of a. supraorbitalis. From the lateral side, a.palpebralis lateralis departs from a.lacrimalis. In the loose connective tissue layer between the musculocutaneous and tarsal-conjunctival plates of the eyelid, these medial and lateral branches of the palpebral arteries are directed towards each other, merge and form transversely located arterial arches: upper and lower - (arcus tarseus sup. et inf., or arr subtarsalis sup.et inf.). Both arterial arches run along the edges of the eyelid, the upper one is 1-2 mm from the edge of the eyelid, the lower one is 1-3 mm. At the level of the upper edge of the cartilage, a second peripheral arc or arcus tarseus sup is formed. On the lower eyelid, it is not always expressed. Between the peripheral and subtarsal arches there are vertical anastomoses with the arteries of the face. In the vascularization of the lower eyelid and the surrounding area are involved and branches of the infraorbital artery, departing from the maxillary artery (from the system of the external carotid artery). These arcs nourish all the tissues of the eyelids. The veins of the eyelid go according to the arteries, forming two networks: superficial and deep. There are much more anastomoses - with veins of the face and veins of the orbit. Because there are no valves in the veins, blood flows both into the venous network of the face and the orbit and through v.ophthalmica. superior, pouring blood into the cavernous sinus (therefore, there is a high probability of infection entering the cranial cavity). On their way to the orbit, the veins that drain blood from the eyelids also penetrate the orbital muscle. Its spasm in diseases of the eyeball (scrofula) can lead to swelling of the eyelids.

The most important anastomoses of the venous network of the eyelids- with the lacrimal vein (v.lacrimalis) and with the superficial temporal (v.temporalis superfacialis). Of particular importance are anastomoses with v.angularis, passing from the inner canthus and anastomosing with v.ophthalmica superior.

lymphatic system- a network of widely branched lymphatic vessels in both deep and subtarsal layers. Both networks anastomose widely with each other. The regional lymph node draining lymph from the upper eyelid is the anterior one, from the region of the lower eyelid it is the submandibular one.

Eyelid innervation

The III and VII pairs of cranial nerves take part in the motor innervation of the eyelids.

Circular muscle of the eye- a branch of the facial nerve (VII pair), its motor fibers provide closure of the eyelids. The facial nerve has a mixed composition: includes motor, sensory and secretory fibers that belong to the intermediate nerve, which is closely related to the facial nerve. The motor nucleus of the nerve is located in the lower part of the pons varolii at the bottom of the IV ventricle, bending around the nucleus of the abducens nerve localized from above, forms the knee (genu n. Facialis) and goes to the base of the brain in the cerebellopontine angle. Then, through the internal auditory opening, it enters the canalis facialis, in which it makes two turns with the formation of a knee and a knee node (geniculum et ganglium gen.). From the node of the knee originates a large stony nerve (n. petrosus major) carrying secretory fibers to the lacrimal gland, extending from a special lacrimal nucleus, and itself facial nerve exits the canal through the foramen stilomastoideum, giving off branches n at this level. auricularis posterior et r. digastricus. Then, with a single trunk, it pierces the parotid gland and divides into upper and lower branches, which give off multiple branches, including the circular muscle of the eye. The muscle that lifts the upper eyelid is innervated by the oculomotor nerve (III pair), only its middle part, i.e. Müller's muscle is a sympathetic nerve.

Nucleus of the oculomotor nerve located at the bottom of the sylvian aqueduct. The oculomotor nerve exits the skull through the superior orbital fissure, attaching sympathetic (from the plexus of the internal carotid artery) and sensory fibers (from n.ophthalmicus), passes through the cavernous sinus. In the orbit, within the muscular infundibulum, it divides into superior and inferior branches. The upper, thinner branch, passing between the upper rectus muscles and the muscle lifting the upper eyelid, innervates them.

Sensitive nerves to the upper eyelid and forehead skin come from the ophthalmic nerve (n.ophthalmicus) of the 1st branch of the trigeminal nerve, which exits through the superior orbital fissure and is divided into three main branches: n.lacrimalis, n.frontalis et n.nasociliaris. In the innervation of the skin of the eyelids, n.frontalis takes the main part., in the medial region of the upper eyelid, its branches n.supraorbitalis et n.supratrochlearis go under the skin. The ophthalmic nerve supplies sensitive innervation to the skin of the forehead, the anterior surface of the scalp, upper eyelid, inner corner of the eye, back of the nose, the eyeball itself, the mucous membranes of the upper part of the nasal cavity, the frontal and ethmoid sinuses, and the meninges. The lower eyelid receives sensitive innervation from n.infraorbitalis, extending from the 2nd branch of the trigeminal nerve (n.maxillaris). maxillary nerve exits the cranial cavity through a round hole and innervates the dura mater, skin, cartilage and conjunctiva of the lower eyelid (except for the innermost and outer corners of the palpebral fissure), lower half the lacrimal sac and the upper half of the nasolacrimal duct, the skin of the anterior part of the temporal region, the upper part of the cheek, the wings of the nose, as well as the upper lip, the upper jaw (and the teeth located on it), the mucous membranes of the posterior part of the nasal cavity and the maxillary sinus.

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Six striated muscles are attached to the eyeball: four straight - upper, lower, lateral and medial and two oblique - upper and lower. All the rectus muscles and the superior oblique begin deep in the orbit at the common tendon ring (anulus tendineus communis), fixed to the sphenoid bone and periosteum around the optic canal and partly at the edges of the superior orbital fissure. This ring surrounds the optic nerve and the ophthalmic artery. From the common tendon ring also begins the muscle that lifts the upper eyelid (m. Levator palpebrae superioris). It is located in the orbit above the superior rectus muscle of the eyeball, and ends in the thickness of the upper eyelid. The rectus muscles are directed along the corresponding walls of the orbit, on the sides of the optic nerve, pierce the vagina of the eyeball (vagina bulbi) and are woven into the sclera in front of the equator with short tendons, 5-8 mm away from the edge of the cornea. The rectus muscles rotate the eyeball around two mutually perpendicular axes: vertical and horizontal (transverse).

The lateral and medial rectus muscles (mm. recti lateralis et medialis) rotate the eyeball outward and inward around the vertical axis, each in its own direction, and the pupil also rotates accordingly. The upper and lower rectus muscles (mm. recti superior et inferior) rotate the eyeball up and down around the transverse axis. The pupil, when the superior rectus muscle contracts, goes up and somewhat outward, and when the lower rectus muscle works, it goes down and inwards. The superior oblique muscle (m. obliquus superior) lies in the upper medial part of the orbit between the superior and medial rectus muscles. Near the trochlear fossa, it passes into a thin round tendon wrapped in the synovial sheath, which is thrown over the block (trochlea), built in the form of a ring of fibrous cartilage. After passing through the block, the tendon lies under the superior rectus muscle and attaches to the eyeball in its upper lateral part, behind the equator. The lower oblique muscle (m. obliquus inferior), unlike the rest of the muscles of the eyeball, begins on the orbital surface of the upper jaw, near the opening of the nasolacrimal canal, on the lower wall of the orbit. The muscle is directed between the lower wall of the orbit and the lower rectus obliquely upward and backward. Its short tendon is attached to the eyeball from its lateral side, behind the equator. Both oblique muscles rotate the eyeball around the anteroposterior axis: the superior oblique muscle rotates the eyeball and pupil downward and laterally, the inferior oblique muscle rotates upward and laterally. The movements of the right and left eyeballs are coordinated due to the friendly action of the oculomotor muscles.

The oculomotor apparatus is a complex sensorimotor mechanism, the physiological significance of which is determined by its two main functions: motor (motor) and sensory (sensitive).

The motor function of the oculomotor apparatus ensures the guidance of both eyes, their visual axes and the central pits of the retinas on the object of fixation, the sensory function - the merging of two monocular (right and left) images into a single visual image.

Innervation of the oculomotor muscles by cranial nerves causes a close relationship between neurological and ocular pathology, which requires an integrated approach to diagnosis.

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Anatomical and physiological features of the muscles of the eye

The movements of the eyeball are carried out with the help of six oculomotor muscles: four straight lines - external and internal (m. rectus externum, m. rectus internum), upper and lower (m. rectus superior, m. rectus inferior) and two oblique - upper and lower ( m. obliguus superior, m. obliguus inferior).

All rectus and superior oblique muscles of the eye begin at the tendon ring located around the canal of the optic nerve at the top of the orbit and fused with its periosteum. The rectus muscles in the form of ribbons are directed anteriorly parallel to the corresponding walls of the orbit, forming the so-called muscle funnel. At the equator of the eye, they pierce the Tenon's capsule (the vagina of the eyeball) and, not reaching the limbus, are woven into the surface layers of the sclera. Tenon's capsule supplies the muscles with a fascial covering that is absent in the proximal region where the muscles begin.

The superior oblique muscle of the eye originates at the tendon ring between the superior and internal rectus muscles and goes anteriorly to the cartilaginous block located in the upper inner corner of the orbit at its edge. At the block, the muscle turns into a tendon and, having passed through the block, turns backwards and outwards. Located under the superior rectus muscle, it attaches to the sclera outside of the vertical meridian of the eye. Two thirds of the entire length of the superior oblique muscle is located between the top of the orbit and the block, and one third is between the block and the place of attachment to the eyeball. This part of the superior oblique muscle determines the direction of movement of the eyeball during its contraction.

In contrast to the five muscles mentioned above, the inferior oblique muscle of the eye begins at the lower inner edge of the orbit (in the area of ​​the entrance of the lacrimal canal), goes posteriorly outward between the wall of the orbit and the inferior rectus muscle towards the external rectus muscle and is fan-shaped attached under it to the sclera in the posterior outer region eyeball, at the level of the horizontal meridian of the eye.

From the fascial sheath of the oculomotor muscles and the Tenon's capsule, there are numerous strands to the walls of the orbit.

The fascio-muscular apparatus provides a fixed position of the eyeball, gives smoothness to its movements.

The muscles of the eye are innervated by three cranial nerves:

• oculomotor nerve - n. osulomotorius (III pair) - innervates the internal, upper and lower rectus muscles, as well as the lower oblique;
• trochlear nerve - n. trochlearis (IV pair) - superior oblique muscle;
• abducens nerve - n. abducens (VI pair) - external rectus muscle.

All of these nerves pass into the orbit through the superior orbital fissure.

The oculomotor nerve divides into two branches after entering the orbit. The superior branch innervates the superior rectus muscle and the levator levator lid muscle, the inferior branch innervates the medial and inferior rectus muscles, as well as the inferior oblique.

The nucleus of the oculomotor nerve and behind it and next to it the nucleus of the trochlear nerve (provides the work of the oblique muscles) are located at the bottom of the Sylvian aqueduct (brain aqueduct). The nucleus of the abducens nerve (provides the work of the external rectus muscle) is located in the pons varoli under the bottom of the rhomboid fossa.

The rectus oculomotor muscles of the eye are attached to the sclera at a distance of 5-7 mm from the limbus, the oblique muscles - at a distance of 16-19 mm.

The width of the tendons at the place of attachment of the muscles ranges from 6-7 to 8-10 mm. Of the rectus muscles, the widest tendon is in the internal rectus muscle, which plays a major role in the implementation of the function of reducing the visual axes (convergence).

Line of insertion of the tendons of the internal and external muscles eyes, i.e., their muscular plane, coincides with the plane of the horizontal meridian of the eye and is concentric to the limbus. This causes horizontal eye movements, adduction, rotation to the nose - adduction during contraction of the internal rectus muscle and abduction, rotation to the temple - abduction during contraction of the external rectus muscle. Thus, these muscles by the nature of action are antagonists.

The upper and lower rectus and oblique muscles of the eye carry out mainly vertical movements of the eye. The line of attachment of the upper and lower rectus muscles is somewhat oblique, their temporal end is further from the limbus than the nasal. As a result, the muscular plane of these muscles does not coincide with the plane of the vertical meridian of the eye and forms an angle with it equal to an average of 20 ° and open to the temple.

Such attachment ensures the rotation of the eyeball under the action of these muscles not only upwards (with contraction of the superior rectus muscle) or downwards (with contraction of the inferior rectus), but simultaneously and inwards, i.e. adduction.

The oblique muscles form an angle of about 60° with the plane of the vertical meridian, open to the nose. This determines the complex mechanism of their action: the superior oblique muscle lowers the eye and produces its abduction (abduction), the inferior oblique muscle is an elevator and also an abductor.

In addition to horizontal and vertical movements, these four oculomotor muscles of the vertical action of the eye perform torsion movements of the eyes clockwise or counterclockwise. In this case, the upper end of the vertical meridian of the eye deviates towards the nose (intorsion) or temple (extorsion).

Thus, the oculomotor muscles of the eye provide the following movements of the eye:

• adduction (adduction), i.e., its movement towards the nose; this function is performed by the internal rectus muscle, additionally by the upper and lower rectus muscles; they are called adductors;
• abduction (abduction), i.e., eye movement towards the temple; this function is performed by the external rectus muscle, additionally by the upper and lower obliques; they are called abductors;
• upward movement - under the action of the upper straight and lower oblique muscles; they are called lifters;
• downward movement - under the action of the lower straight and upper oblique muscles; they are called droppers.

The complex interactions of the oculomotor muscles of the eye are manifested in the fact that when moving in one direction they act as synergists (for example, partial adductors - the upper and lower rectus muscles, in others - as antagonists (the upper rectus is the lifter, the lower rectus is the lowerer).

The oculomotor muscles provide two types of friendly movements of both eyes:

• unilateral movements (in the same direction - to the right, to the left, up, down) - the so-called version movements;
• opposite movements (in different directions) - vergent, for example, towards the nose - convergence (reduction of the visual axes) or to the temple - divergence (breeding of the visual axes), when one eye turns to the right, the other to the left.

Vergence and version movements can also be performed in vertical and oblique directions.

There are only six oculomotor muscles, four of them are straight, two are oblique. This name was given to the muscles because of the peculiarities of their course in the orbit, as well as attachment to the apple of the eye. The work of the muscles is controlled by three cranial nerves: oculomotor, abducent, block. Each muscle fiber of this muscle group is rich in nerve endings, which provides movements with special accuracy and clarity.

Thanks to the oculomotor muscles, the variability of the movements of the eyeballs is ensured, including unidirectional - up, to the right, etc., and multidirectional - bringing the eyes together. The essence of such movements lies in the fact that due to the well-coordinated muscular work, the same image of the object falls on one part of the retina - the macular region, which provides good vision, gives a sense of spatial depth.

It is customary to distinguish six oculomotor muscles, four of them go in the forward direction and are called straight: internal, external, upper, lower. The two remaining ones have a somewhat oblique direction of travel, as well as a way of attaching the eye to the apple, and therefore they are called oblique: upper and lower.

All muscles, excluding the inferior oblique, originate in a dense ring of connective tissue that surrounds the external opening in the optic canal. At the very beginning, 5 muscles form a kind of muscular funnel, where the optic nerve, blood vessels and nerves pass. After, the superior oblique muscle deviates gradually upward and inward, moving towards the so-called block. This is the place where the muscle transforms into a tendon thrown through the loop of the block, which is why it changes direction to oblique, then attaching in the region of the upper outer quadrant of the eyeball below the superior rectus muscle. The inferior oblique muscle originates from the infero-internal orbital margin, passes below the inferior rectus muscle outwards and backwards, and inserts in the region of the infero-outer quadrant of the eyeball.

In the immediate vicinity of the eyeball, a surface layer appears in the muscles - a dense capsule of the Tenon membrane. Their attachment to the sclera occurs at a different distance from the limbus. Especially close to the limbus of the rectus muscles, the inner one is attached, and farther than the rest, the upper rectus. The oblique muscles are attached to the apple of the eye a little behind the equator of the eyeball - the middle of its length.

The work of the muscles, to a greater extent, regulates the oculomotor nerve. It governs the internal, superior, inferior oblique, and inferior rectus muscles. The functions of the external rectus muscle are coordinated by the abducens nerve, while the superior oblique muscle is controlled by the trochlear nerve. The peculiarity of such nervous regulation is that one branch of the motor nerve controls the work of a very small number of muscle fibers, which makes it possible to ensure maximum accuracy in eye movements.

The movements of the eyeball are completely dependent on the features of muscle attachment. The attachment zone of the external and internal rectus muscles corresponds to the horizontal plane of the eyeball, which provides horizontal movements: turning them towards the nose (contraction of the internal rectus muscle) or to the temple (contraction of the external rectus muscle).

The lower and upper rectus muscles provide mainly vertical eye movements, but due to the fact that the line of attachment of the muscles is localized somewhat obliquely with respect to the limbus line, along with the vertical movement of the eyes, their inward movement also occurs.

Oblique muscles, contracting, cause more complex movements, this is due to certain features of the location of the muscles, as well as their attachment to the sclera. The function of the superior oblique muscle is to lower the eye and turn it outward, and the function of the inferior oblique muscle is to raise it and take it outward.

At the same time, the superior and inferior rectus and oblique muscles are able to provide small turns of the eye clockwise or counterclockwise. Good nervous regulation, as well as well-coordinated work of the muscles of the eyeball, make it possible to perform complex movements: unilateral or directed in different directions, which ensures the volume and quality of vision, its binocularity.

Video about the structure of the muscles of the eye

Diagnostic methods

• Visual study of eye mobility, with an assessment of the completeness of movements when tracking a moving object.
• Strabometry - assessment of the angle of deviation of the eye in strabismus from the midline.
• A test with alternately covering the eyes, which determines latent strabismus - heterophoria, and with obvious strabismus, which determines its appearance.
• Ultrasound diagnostics, to determine the lesions of the oculomotor muscles, localized close to the eyeball.
• Magnetic resonance imaging, computed tomography - detection of lesions of the oculomotor muscles throughout.

Symptoms of diseases

• Double vision - the condition may be due to obvious strabismus or pronounced latent strabismus.
• Nystagmus - occurs due to a violation of the ability to fix objects with a glance.
• Violation of friendly eye movement, limitation of mobility of the affected eye.
• Pain aggravated by eye movement.
• Omission of the eyelid.
• binocular vision disorder.

Diseases affecting the muscles of the eye

• Strabismus.
• Ptosis.
• Muscle inflammation (myositis).
• Lagophthalmos.
• Blepharospasm.
• Heterophoria.
• Refractive error (myopia, hypermetropia).