Skin of the eyelids very thin and mobile, since their subcutaneous tissue is extremely loose and devoid of fat. This contributes easy occurrence and the rapid spread of edema during local inflammatory processes, with venous stagnation and some common diseases. The looseness of the subcutaneous tissue also explains the rapid spread of bruising and subcutaneous emphysema of the eyelids.
Sensory nerves of the skin of the eyelids come from the trigeminal nerve. The upper eyelid is innervated by terminal branches coming from the first branch of the trigeminal nerve, and the lower eyelid is innervated by the second branch.
Located under the skin orbicularis eyelid muscle(m. orbicularis oculi), innervated by the facial nerve, consists of two parts - palpebral and orbital. When only the palpebral part is contracted, the eyelids slightly close; their complete closure is achieved by contraction of both parts of the muscle. Muscle fibers running parallel to the edge of the eyelids between the roots of the eyelashes and around the excretory ducts of the meibomian glands form the Riolan muscle; it presses the edge of the eyelid to the eye and promotes the removal of secretions from the meibomian glands to the surface of the intermarginal edge of the eyelid. Excessive tension of the orbicularis muscle leads to blepharospasm, and often to spastic volvulus, which can also be caused by contraction of the Riolan muscle, especially in the elderly.
It should be noted that with pronounced and prolonged spasm of the muscle, significant swelling of the eyelids also develops, since this greatly compresses the eyelid veins that pass between the fibers of the orbicularis muscle. Paralysis facial nerve can lead to inversion of the lower eyelid and non-closure of the palpebral fissure (lagophthalmos).
TO eyelid muscles also includes the levator muscle upper eyelid(m. levator palpebrae superior), innervated by the oculomotor nerve. Starting deep in the orbit, the levator reaches the cartilage and attaches to its upper edge and anterior surface. Between the two tendon layers of the levator there is a layer of smooth fibers - the Müller muscle, innervated by the sympathetic nerve; it is also attached to the upper edge of the cartilage. In the lower eyelid there is no muscle similar to the levator, but there is a Müller muscle (m. tarsalis inferior). An isolated contraction of the Müller muscle causes only a slight widening of the palpebral fissure, therefore, with sympathetic nerve palsy, slight ptosis is observed, while ptosis with levator palsy is more pronounced and may even be complete.
A solid foundation for the century forms cartilage (tarsus), consisting of dense connective tissue. The physiological significance of the eyelid cartilage, in addition to its protective function, is due to the presence of meibomian glands in its thickness, the secretion of which lubricates the intermarginal edge of the eyelid, protecting the skin of the eyelids from maceration by tear fluid. The most important feature The structure of the eyelids is their extremely rich blood supply. Numerous arteries anastomosing among themselves originate from two systems - from the ophthalmic artery system and from the facial artery system. Arterial branches running towards each other merge and form arterial arches - arcus tarseus. There are usually two of them on the upper eyelid, and often one on the lower eyelid.
The abundant blood supply to the eyelids is, of course, of great practical importance; in particular, this explains the excellent healing of eyelid wounds both with extensive damage and during plastic surgery.
Veins of the eyelids even more numerous than arteries; outflow from them occurs both in the veins of the face and in the veins of the orbit. It is necessary to emphasize that the orbital veins do not have valves, which are to a certain extent a natural barrier to the flow of venous blood. In view of this, severe infectious diseases of the eyelids (abscess, erysipelas, etc.) can spread directly through the venous bed not only into the orbit, but also into the cavernous sinus and cause the development of purulent meningitis.
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The eyelids are movable structures that protect the eyeball from the front. There are upper (palpebra superior) and lower (palpebra inferior) eyelids. Thanks to the mobility of the eyelids, namely due to their blinking, the tear fluid is evenly distributed over the front surface of the eye, moisturizing the cornea and conjunctiva. The connection of the upper and lower eyelids occurs through the medial commissure (commissura medialis palpebrarum) and the lateral commissure (commissura lateralis palpebrarum), which begin respectively in the outer (angulus oculi lateralis) and inner corner of the eye (angulus oculi medialis).
In the inner corner, at a distance of approximately 5 mm before the junction of the eyelids, a recess is formed - the lacrimal lake (lacus lacrimalis). At its bottom there is a rounded pink tubercle - the lacrimal caruncle (caruncula lacrimalis), to which is adjacent the semilunar fold of the conjunctiva (plica semilunaris conjunctivae). The almond-shaped space between the open eyelids is called the palpebral fissure (rima palpebrarum). Its horizontal length in an adult is 30 mm, and its height in the center is from 10 to 14 mm. When the eyelids are closed, the palpebral fissure completely disappears.
In the eyelids, two plates are conventionally distinguished - the outer (musculocutaneous) and the inner (conjunctival-cartilaginous). The skin of the eyelids contains sebaceous sweat glands. The subcutaneous tissue of the eyelids is devoid of fat, so swelling and hemorrhages easily spread in it, it easily folds, forming upper and lower folds that coincide with the corresponding edges of the cartilage. The cartilages of the eyelids (tarsus superior et inferior) look like a slightly convex plate about 20 mm long, up to 12 mm high and about 1 mm thick. The height of the cartilage on the lower eyelid is 5-6 mm; on the upper eyelid the cartilage is more pronounced. Cartilage consists of dense connective tissue and does not have its own cartilage cells. They are connected to the upper and lower walls of the orbit by ligaments of the eyelids (lig. palpebrale mediale et laterale).
The orbital part of the cartilage is connected to the edges of the orbit through dense fascia (septum orbitale). The cartilages contain elongated alveolar glands (glandulae tarsales), about 20 of them in the lower eyelid and 25 in the upper. The glands are located in parallel rows, their excretory ducts open near the posterior free edge of the eyelids. The lipid secretion of the glands lubricates the intercostal space of the eyelids, forming the outer layer of the precorneal tear film, which prevents tears from rolling down through the lower edge of the eyelid.
The connective tissue membrane (conjunctiva) covering the back surface of the eyelids is tightly fused with cartilage. When the conjunctiva passes from the eyelids to the eyeball, it forms movable vaults - upper and lower. The edges of the eyelids, forming the palpebral fissure, are limited in front by the anterior rib, and behind by the posterior rib. The narrow strip between them, up to 2 mm wide, is called the intercostal (intermarginal) space; here are located the roots of the eyelashes in 2-3 rows, sebaceous glands (Zeiss glands), modified sweat glands (Moll glands), openings of the excretory ducts of the meibomian glands. At the inner corner of the eye, the intermarginal space narrows and passes into the lacrimal papilla (papilla lacrimalis), at the top of which there is an opening - the lacrimal punctum (punctum lacrimale); it is immersed in the lacrimal lake and opens into the lacrimal canaliculus (canaliculus lacimalis).
Eyelid muscles
Under the skin of the eyelids, ensuring their mobility, there are two groups of muscles - antagonists in the direction of action: the circular muscle of the eye (m. orbicularis oculi) and the muscle that lifts the upper eyelid (m. levator palpebrae superioris).
Orbicularis oculi muscle consists of the following parts: orbital (pars orbitalis), palpebral, or age-old (pars palpebralis), and lacrimal (pars lacrimalis). The orbital part is a circular belt, the fibers of which are attached to the medial ligament of the eyelids (lig. parpebrale mediale) and the frontal process of the maxilla. When this part contracts, the eyelids close tightly. The fibers of the palpebral part begin from the medial ligament of the eyelids and, forming an arc, reach the outer corner of the eye, attaching to the lateral ligament of the eyelids. When this muscle group contracts, the eyelids close and blink.
The lacrimal part is a group of muscle fibers that start from the posterior lacrimal crest of the lacrimal bone (os lacrimalis), then pass behind the lacrimal sac (saccus lacrimalis), intertwining with the fibers of the palpebral part. The muscle fibers enclose the lacrimal sac in a loop, as a result of which, when the muscle contracts, the lumen of the lacrimal sac either expands or narrows. Thanks to this, the process of absorption and movement of tear fluid along the lacrimal ducts occurs.
There are muscle fibers of the orbicularis oculi muscle, which are located between the roots of the eyelashes around the duct of the meibomian glands (m. ciliaris Riolani). Contraction of the fibers promotes the secretion of the mentioned glands and a tight fit of the edge of the eyelids to the eyeball. The circular muscle is innervated by the zygomatic (rr. zygomatici) and temporal (rr. temporales) branches of the facial nerve.
Levator superioris muscle, begins near the optic canal (canalis opticus), goes under top part orbit and ends in three muscle plates. The superficial plate, forming a wide aponeurosis, perforates the tarso-orbital fascia and ends above the skin of the eyelid. The middle one consists of a thin layer of smooth fibers (m. tarsalis superior, m. Mulleri), intertwined with the upper edge of the cartilage, innervated by sympathetic nerve fibers. A deep plate in the form of a wide tendon reaches the upper fornix of the conjunctiva and is attached there. The superficial and deep plates are innervated by the oculomotor nerve.
The lower eyelid is retracted muscle of the lower eyelid cartilage(m. tarsalis inferior) and fascial processes of the inferior rectus muscle (m. rectus inferior).
Blood supply
The blood supply to the eyelids is carried out through the branches of the ophthalmic artery (a. ophthalmica), which is part of the internal carotid artery system, as well as anastomoses from the facial and maxillary artery(aa. facialis et maxiaJlaris) from the external carotid artery system. These arteries branch and form arterial arches: two on the upper eyelid, one on the lower. The arteries correspond to veins through which the outflow of venous blood occurs mainly towards the angular vein (v. angularis), the vein of the lacrimal gland (v. lacrnnalis) and the temporal superficial vein (v. temporalis superfirialis). The structural features of these veins include the absence of valves and the presence of a large number of anastomoses. It is clear that such features can cause the development of severe intracranial complications, for example, with the development of purulent processes on the face.
Lymphatic system
The lymphatic network is well developed on the eyelids; There are two levels, which are located on the anterior and posterior surfaces of the cartilage. Lymphatic vessels upper eyelid drain into the pre-auricular lymph nodes, the lower eyelid - into the submandibular lymph nodes.
Innervation
The branches of the facial nerve (n. facialis) and three branches of the trigeminal nerve (n. trigeminus), as well as the great auricular nerve (n. auricularis majos) provide sensitive innervation to the skin of the face. The skin and conjunctiva of the eyelid are innervated by two main branches of the maxillary nerve (n. maxillaris) - the infraorbital (n. infraorbitalis) and zygomatic (n. zygomaticus) nerve.
Eyelid research methods
To study the condition of the eyelids, the following research methods are used:
1. External examination of the eyelids, palpation.
2. Inspection with side (focal) lighting.
3. Inspection of the mucous membrane of the eyelids when everting the upper and lower eyelids.
4. Biomicroscopy.
Diseases of the eyelids
Among total number patients with inflammatory diseases 23.3% of eyes are patients with inflammation of the eyelids. The pathology of the auxiliary and protective apparatus of the eyes is of great socio-economic importance, as it is one of the most common reasons temporary disability and can lead to significant complications from the organ of vision.
Zhaboyedov G.D., Skripnik R.L., Baran T.V.
Origin: tendon ring around the optic canal
Attachment – cartilage of the upper eyelid
Function: raises the upper eyelid
VISUAL ANALYZER. VISUAL PATHWAY
Location of 1 neurons: Rods and cones, located in the retina, are converted neurons. Convert the energy of light quanta into a nerve impulse;
The course of axons of 1 neurons: inside the retina, to bipolar neurons;
Location of 2 neurons: Bipolar neurons, located in the retina, send axons to ganglion neurons;
The course of axons of 2 neurons: run in the retina and end at synapses on ganglion neurons
Location of 3 neurons: In the retina. The axons of ganglion neurons, leaving the eyeball, form the optic nerve;
The course of the axons of 3 neurons: Optic nerve (through the optic canal it enters the middle cranial fossa), Optic chiasm (Axons coming from the medial retinal fields cross at the chiasm and go into the optic tract of the opposite side; axons coming from the lateral retinal fields go into the optic tract of their side) , optic tract, further:
Lateral geniculate body (Ends with synapses on neurons of the nucleus of the lateral geniculate body);
Superior colliculus (ends with synapses on neurons of the nucleus of the superior colliculus)
The course of the axons of 4 neurons:
A) From the nucleus of the lateral geniculate body:
Posterior limb of the internal capsule (forms optic radiation), occipital lobe the hemispheres of the telencephalon, where they end in the cortical nucleus of the visual analyzer (Wedge, calcarine sulcus, lingual gyrus);
B) From the nucleus of the superior colliculus:
To the nuclei of the oculomotor nerve (III FMN pair), which control the movements of the muscles of the eyeball, accommodation and pupil diameter;
Through the posterior longitudinal fasciculus to the nuclei of the IV and VI pairs of cranial nerves and motor neurons of the cervical spinal cord
INNERVATION OF THE GAZE
This is a mechanism for controlling the synchronous rotation of the eyeballs and head towards the object of observation. The center of gaze innervation is located in the premotor zone of the left hemisphere. The conducting path from the center is directed to the bridge to the nuclei of the abducens nerves. From there, synchronizing commands through the posterior longitudinal fasciculus enter the midbrain to the nuclei of the oculomotor and trochlear nerves, as well as to the motor neurons of the cervical spinal cord.
CONTROL QUESTIONS
1. Specify the membranes of the eyeball
2. Indicate the parts of the light-refracting apparatus of the eyeball
3. Specify the parts of the tunica albuginea
4. Specify the parts choroid
5. Describe the structure ciliary body
6. What is the mechanism of accommodation?
7. Describe the structure of the iris
8. Describe the structure of the lens
9. Describe the structure of the anterior and posterior chambers of the eyeball
10. Indicate the place of formation and the route of outflow of aqueous humor
11. Describe the structure of the retina
12. Muscles of the eyeball: their location, origin, attachment, function;
13. Lacrimal apparatus: its parts, their structure. The path of outflow of tear fluid.
14. Conjunctiva, its structure and function.
15. Eyelids, their structure and function.
16. Visual pathway: its links, subcortical centers, cortical nucleus
Eyelids, palpebrae (Greek blepharon) , upper eyelid, palpebra superior, and lower eyelid, palpebra inferior, are folds of skin that limit the front of the eyeball.
When the eyelids are closed, they completely cover the eyeball; when the eyelids are open, their edges limit the eyelid fissure (palpebral fissure), rima palpebrarum; The upper eyelid is larger than the lower.
In each eyelid, there are anterior and posterior surfaces of the eyelids and two edges that form the eyelid fissure.
The anterior surface of the eyelid, facies anterior palpebrae, both upper and lower, is convex and covered with skin, which contains many sebaceous and sweat glands.
The upper eyelid is limited at the top eyebrow, supercilium. The eyebrow is a ridge-like projection of skin along the upper edge of the eye socket. It is more convex in the medial sections and becomes thinner in the outer sections. The surface of the eyebrow is abundantly covered with small hairs. When the upper eyelid is raised, its skin at the level of the upper edge of the orbit forms a noticeable superior groove.
The lower eyelid is separated from the cheek by a faint groove under the eyelid. When the eyelid is drooping, its skin at the level of the lower edge of the orbit, as in the area of the upper eyelid, forms a lower groove. The orbital edge of the eyelid is the place of transition of its skin into the skin of adjacent areas.
Along the inner edge of the surface of the eyelids, a faint vertical eyelid fold is sometimes visible, plica palpebronasalis, having a slightly concave shape and bending around the medial ligament of the eyelids from the inside.
The free edge of the eyelid is up to 2 mm thick. This edge of the eyelid is arched anteriorly for most of its length, only in the medial section does the curvature disappear.
Here the edges of the upper and lower eyelids become curved upward and downward, respectively, and, connecting to each other using the medial commissure of the eyelids, commissura palpebrarum medialis, form a rounded medial corner of the eye, angulus oculi medialis.
On the lateral side of the eyelids, connecting into the lateral commissure of the eyelids, commissura palpebrarum lateralis, form the acute lateral angle of the eye, angulus oculi lateralis.
Between the edges of the upper and lower eyelids, at the inner corner of the eye, there is a pinkish-colored elevation called the lacrimal caruncle, caruncula lacrimalis, around which there is a lake of tears, lacus lacrimalis. Inward to the lacrimal caruncle there is a small vertical fold of the conjunctiva, called the semilunar fold of the conjunctiva, plica semilunaris conjunctivae, being a vestigial third eyelid.
The edge of the eyelid passes into the anterior and posterior surfaces of the eyelid, separated from them by the anterior and posterior edges of the eyelid, respectively, limbis palpebrales anterior et posterior.
The anterior edge of the eyelid is somewhat rounded. Behind it, many hairs emerge from the thickness of the eyelid - eyelashes, cilia, curved downward at the lower eyelid, and upward at the upper one. Immediately, the excretory ducts of the sebaceous and modified sweat glands associated with the hair bags of the eyelashes open.
The edges of the upper and lower eyelids at the medial corner of the eye at the level of the outer periphery of the lacrimal caruncle bear a small elevation - the lacrimal papilla, papilla lacrimalis. This is where the superior and inferior lacrimal canaliculi begin. canaliculi lacrimales which open at the top of the eyelid papillae with clearly visible openings - lacrimal puncta, puncta lacrimalia.
The posterior edge of the eyelid passes directly into the posterior surface of the eyelid, facies posterior palpebrae.
The posterior surface of the eyelid is concave and covered throughout with the conjunctiva of the eyelids, tunica conjunctiva palpebrarum. The conjunctiva begins from the posterior edge of the eyelids and, having reached the orbital edge of the upper and lower eyelids, turns back and goes to the eyeball. This part of the conjunctiva is called the conjunctiva of the eyeball, tunica conjunctiva bulbi. Covering the anterior parts of the eyeball, the conjunctiva reaches the limbus of the cornea, forming a conjunctival ring at the junction of the sclera and the cornea, anulus conjunctivae. The conjunctiva of the eyeball is loosely connected to the sclera.
The transition of the conjunctiva of the eyelid into the conjunctiva of the eyeball forms the upper and lower fornix of the conjunctiva, fornices conjunctivae superior et inferior, which, together with other parts of the conjunctiva, limit the conjunctival sac, saccus conjunctivalis, open anteriorly along the line of the palpebral fissure and closed when the eyes are closed.
In the area of the upper and lower fornix, the conjunctiva forms a series of folds. In the thickness of the conjunctiva there are single conjunctival glands, glandulae conjunctivales.
The part of the eyelid located between the skin and the conjunctiva consists of a number of formations. Directly under the skin lies the orbicularis oculi muscle.
In the upper eyelid, behind this muscle, there is a tendon of the muscle that lifts the upper eyelid, m. levator palpebrae superioris; this muscle starts from the periosteum top wall of the orbit in front of the optic canal, goes forward and, near the upper edge of the orbit, becomes a flat tendon. The latter, entering the thickness of the upper eyelid, is divided into two plates: a superficial plate, lamina superficialis, which is located first behind the orbicularis oculi muscle, and then, perforating it with its fibers, goes to the skin of the eyelid, and a deep plate, lamina profunda, attached to the upper edge of the cartilage of the upper eyelid.
Deeper than the orbicularis oculi muscle and closer to the free edge lie, respectively, the upper cartilage of the eyelid, tarsus superior, and the lower cartilage of the eyelid, tarsus inferior, which is somewhat narrower than the upper one. They are formed by fibrous cartilage tissue and are durable. In the cartilage of the eyelid, there are posterior and anterior surfaces and two edges - orbital and free.
The posterior surface of the cartilaginous plate is concave corresponding to the convex surface of the eyeball and is tightly fused with the conjunctiva of the eyelid, which determines the smooth surface of the conjunctiva in this area.
The anterior surface of the eyelid cartilages is convex and connected to the orbicularis oculi muscle through loose connective tissue.
The free edges of the upper and lower eyelid cartilages are relatively smooth and facing each other. The orbital margins are arched, and in the upper cartilage of the eyelid this curvature is more pronounced. The length of the free edge of the eyelid cartilage is 20 mm, thickness 0.8-1.0 mm; the height of the upper eyelid is 10-12 mm, the lower - 5-6 mm.
The orbital edges of the cartilages are fixed at the corresponding edge of the orbit by means of the orbital fascia, fascia orbitalis, and muscles of the upper and lower eyelid cartilages.
In the area of the medial and lateral corners of the eye, the cartilages of the eyelids are connected to each other and fixed to the corresponding bone walls of the orbit through the medial and lateral ligaments of the eyelids, ligament a palpebrarum mediale et laterale.
The lateral ligament of the eyelid is divided by the lateral suture of the eyelid, raphe palpebralis lateralis, located horizontally.
The cartilages of the eyelids, located near the free edge of the eyelid, give this part a certain density, due to which it is called the cartilaginous part of the eyelid, in contrast to the rest of the eyelid, which is less dense and called the orbital part of the eyelid.
The corresponding small upper and lower muscles of the eyelid cartilages approach the cartilages of the eyelids. The peculiarity of these muscles is that, being built from smooth muscle tissue, they attach to skeletal muscles, attaching with them to the cartilage of the eyelids.
Upper eyelid cartilage muscle, m. tarsalis superior, joining the muscle that lifts the upper eyelid, is fixed to the inner surface of the upper edge of the upper cartilage, and the lower muscle of the cartilage of the eyelid, m. tarsalis inferior, connecting with the fibers of the inferior rectus muscle, is fixed to the lower edge of the lower cartilage of the eyelid.
In the cartilaginous plates of the upper and lower eyelids lie peculiarly modified sebaceous glands - the glands of the cartilage of the eyelid, glandulae tarsales; in the upper eyelid there are 27-40 of them, in the lower eyelid 17-22.
The excretory ducts of these glands open in the intermarginal space closer to the posterior edge, and the main sections are directed towards the orbital edge of the eyelid and, accordingly, the configuration of the eyelid cartilage is curved in the sagittal plane. The end parts of the main sections of the glands do not extend beyond the cartilage. In the upper eyelid, the glands do not occupy the entire cartilaginous plate, but leave its upper edge free; in the lower eyelid they occupy the entire cartilaginous plate.
In the upper eyelid, the glands are unequal in length along the entire length of the cartilaginous plate; in the middle section the glands are longer. In the lower eyelid there are no such sharp differences in the size of the glands.
On the free edge of the eyelids between the eyelashes, the ducts of the ciliary glands also open, glandulae ciliares, and the sebaceous glands approach the hair follicles of the eyelashes, glandulae sebaceae.
In addition to these glands, non-permanent lacrimal cartilaginous glands are found in the lower and upper cartilages of the eyelids.
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Description
Sensitive 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, nasociliary and frontal.
The lacrimal nerve innervates the lacrimal gland, the outer parts of the conjunctiva of the eyelids and eyeball, and the skin of the lower and upper eyelids.
The nasociliary nerve gives off a branch to the ciliary ganglion, 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 the cornea. At the edge of the cornea, they enter the middle sections of its own substance, losing their myelin coating. Here the nerves form the main plexus of the cornea. Its branches under the anterior border plate (Bowman's) form one plexus of the “closing chain” type. The stems coming from here, piercing the border plate, fold on its anterior surface into the so-called subepithelial plexus, from which branches extend, ending with terminal sensory devices directly in the epithelium.
The frontal nerve is divided into two branches: supraorbital and supratrochlear. All branches, anastomosing among themselves, innervate the middle and inner part of the skin of the upper eyelid.
Ciliary, or ciliary, the node is located in the orbit on the outside 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 ganglion includes sensory fibers of the nasopharynx 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 ganglion, penetrating the eyeball through the posterior part of the sclera and supplying the eye tissue with sensitive parasympathetic and sympathetic fibers. Parasympathetic fibers innervate the sphincter of the pupil and the ciliary muscle. Sympathetic fibers go to the dilator muscle.
The oculomotor nerve innervates all the rectus muscles except the external one, as well as the inferior oblique, levator superior pallidum, sphincter pupillary muscle, and ciliary muscle.
The trochlear nerve innervates the superior oblique muscle, and the abducens nerve innervates the external rectus muscle.
The orbicularis oculi muscle is innervated by a branch of the facial nerve.
Adnexa of the eye
TO adnexa The eyes include the eyelids, conjunctiva, tear-producing and tear-draining organs, and retrobulbar tissue.
Eyelids (palpebrae)
The main function of the eyelids is protective. The eyelids are a complex anatomical formation that includes two layers - musculocutaneous and conjunctival-cartilaginous.
The skin of the eyelids is thin and very mobile, freely gathers into folds when opening the eyelids and also freely straightens when they close. Due to mobility, the skin can easily be pulled to the sides (for example, by scars, causing eversion or inversion of the eyelids). The displaceability, mobility of the skin, the ability to stretch and move are used in plastic surgery.
Subcutaneous tissue is represented by a thin and loose layer, poor in fatty inclusions. As a result, severe swelling easily occurs here due to local inflammatory processes, and hemorrhages due to injuries. When examining a wound, it is necessary to remember about the mobility of the skin and the possibility of large displacement of the wounding object in the subcutaneous tissue.
The muscular part of the eyelid consists of the orbicularis palpebral muscle, the levator palpebrae superioris, the Riolan muscle (a narrow strip of muscle along the edge of the eyelid at the root of the eyelashes) and the Horner muscle (muscle fibers from the orbicularis muscle that surround the lacrimal sac).
The orbicularis oculi muscle consists of the palpebral and orbital bundles. The fibers of both bundles begin from the internal 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 run in arcuate rows. The fibers of the orbital part in the area of the outer corner pass to the other eyelid and form a complete circle. The orbicularis 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 is attached 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 orbicularis oculi muscle is a dense connective tissue plate called eyelid cartilage, although it does not contain cartilage cells. The cartilage gives the eyelids a slight bulge that follows the shape of the eyeball. The cartilage is connected to the edge of the orbit by a dense tarso-orbital fascia, which serves as the topographic boundary of the orbit. The contents of the orbit include everything that lies behind the fascia.
In the thickness of the cartilage, perpendicular to the edge of the eyelids, there are modified sebaceous glands - meibomian glands. Their excretory ducts exit into the intermarginal space and are located along the posterior edge of the eyelids. The secretion of the meibomian glands prevents the overflow of tears over 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 artery. Both are terminal branches of the ophthalmic artery. The greatest 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. Considering the high displacement capacity of eyelid tissues, minimal removal of damaged areas during primary surgical treatment is desirable.
The outflow of venous blood from the eyelids goes to the superior ophthalmic 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 and sinuses can quickly spread to the orbit and into the cavernous sinus.
The regional lymph node of the upper eyelid is the submandibular lymph node, and the lower one is the submandibular lymph node. This must be taken into account during the spread of infection and metastasis of tumors.
Conjunctiva
The conjunctiva is the thin mucous membrane that lines the back surface of the eyelids and the front surface of the eyeball up to the cornea. The conjunctiva is a mucous membrane richly supplied with vessels and nerves. She easily responds to any irritation.
The conjunctiva forms a slit-like cavity (bag) between the eyelid and the eye, which contains the capillary layer of tear fluid.
In the medial direction, the conjunctival sac reaches the inner corner of the eye, where the lacrimal caruncle and the semilunar fold of the conjunctiva (vestigial 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 sections of the conjunctiva: the conjunctiva of the eyelids, the conjunctiva of the fornix (upper and lower) and the conjunctiva of the eyeball.
The conjunctiva is a thin and delicate mucous membrane, consisting of a superficial epithelial and deep submucosal layer. The deep layer of the conjunctiva contains lymphoid elements and various glands, including lacrimal glands, which provide mucin and lipids for the superficial tear film covering 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 quite transparent, through it you can see the translucent glands of the cartilage of the eyelids (meibomian glands). The surface layer of the conjunctiva of the eyelid is lined with multirow columnar epithelium, which contains a large number of goblet cells that produce mucus. Under normal physiological conditions there is little of this mucus. Goblet cells respond to inflammation by increasing their numbers and increasing secretion. When the conjunctiva of the eyelid becomes 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 special forms follicular lesions of the conjunctiva.
An increase in 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.
Conjunctiva of the fornix. In the fornix (fornix conjunctivae), where the conjunctiva of the eyelids passes into the conjunctiva of the eyeball, the epithelium changes from multilayered cylindrical to multilayered flat.
Compared to other sections in the vault area, the deep layer of the conjunctiva is more pronounced. Numerous glandular formations are well developed here, including small additional lacrimal jelly (Krause's glands).
Under the transitional folds of the conjunctiva there is a pronounced layer of loose fiber. This circumstance determines the ability of the conjunctiva of the fornix to easily fold and straighten, which allows the eyeball to maintain full mobility.
Cicatricial changes in the conjunctival fornix limit eye movements. Loose fiber under the conjunctiva contributes to the formation of edema here during inflammatory processes or congestive vascular phenomena. The upper conjunctival fornix is wider than the lower one. The depth of the first is 10-11 mm, and the second - 7-8 mm. Typically, the superior fornix of the conjunctiva extends beyond the superior orbitopalpebral groove, and the inferior fornix is at the level of the inferior orbitopalpebral fold. In the upper outer part of the upper fornix, pinpoint openings are visible, these are the mouths of the excretory ducts of the lacrimal gland
Conjunctiva of the eyeball (conjunctiva bulbi). It distinguishes between a movable part, covering the eyeball itself, and a part of the limbus region, fused to the underlying tissue. From the limbus, the conjunctiva passes to the anterior surface of the cornea, forming its epithelial, optically completely transparent layer.
The genetic and morphological similarity of the epithelium of the conjunctiva of the sclera and cornea determines the possibility of transition pathological processes from one part to another. This occurs with 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 cornea area. The stratified squamous epithelium of the conjunctiva of the eyeball is non-keratinizing and under normal physiological conditions retains this property. The conjunctiva of the eyeball is much more abundant than the conjunctiva of the eyelids and fornix, equipped with sensitive nerve endings (the first and second branches of the trigeminal nerve). In this regard, the entry into the conjunctival sac of even small foreign bodies or chemicals causes very unpleasant feeling. It is more significant with inflammation of the conjunctiva.
The conjunctiva of the eyeball is not connected to 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 an instrument. This circumstance is used when performing plastic surgery when relocation of areas of the conjunctiva is required.
Along the perimeter of the limbus, the conjunctiva is fixed quite firmly, as a result of which, with significant swelling, a vitreous shaft is formed in this place, sometimes hanging over the edges of the cornea.
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 links of the microcircular network. Many intramural blood vessels of the conjunctiva ensure the vital activity of all its structural components.
By changing the pattern of blood vessels in certain areas of the conjunctiva (conjunctival, pericorneal and other types of vascular injections) it is possible differential diagnosis diseases associated with the pathology of the eyeball itself, with diseases of purely conjunctival origin.
The conjunctiva of the eyelids and eyeball is supplied with blood from the arterial arches of the upper and lower eyelids and from the anterior ciliary arteries. The arterial arches of the eyelids are formed from the lacrimal and anterior ethmoidal arteries. The anterior ciliary vessels are branches of the muscular arteries that supply blood to the external 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 system of the internal carotid artery. However, the lateral arteries of the eyelids, from which branches supplying part of the conjunctiva of the eyeball arise, 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 the accompanying veins form conjunctival vessels, which in the form of numerous stems go to the conjunctiva of the sclera from both anterior folds. The anterior ciliary arteries of the scleral tissue run above the area 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 anastomosing with them form the superficial (subepithelial) body of the vessels of the conjunctiva of the eyeball. This layer contains the greatest number of elements of the microcircular bed of the bulbar conjunctiva.
The branches of the anterior ciliary arteries, anastomosing with each other, as well as the tributaries of the anterior ciliary veins form the marginal circumference of the limbus, or the perilimbal vascular network of the cornea.
Lacrimal organs
The lacrimal organs consist of two separate topographically distinct departments, namely the tear-producing and lacrimal-discharge parts. The tear performs protective (washes out foreign elements from the conjunctival sac), trophic (nourishes the cornea, which does not have its own vessels), bactericidal (contains nonspecific factors immune defense- lysozyme, albumin, lactoferin, b-lysine, interferon), moisturizing functions (especially the cornea, maintaining its transparency and being part of the precorneal film).
Tear-producing organs.
Lacrimal gland (glandula lacrimalis) in its anatomical structure it is very similar to the salivary glands and consists of many tubular glands, collected in 25-40 relatively separate lobules. The lacrimal gland, by the lateral portion of the aponeurosis of the muscle that lifts the upper eyelid, is divided into two unequal parts, 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, diameter is 12-14 mm and thickness is about 5 mm. In shape and size it resembles a bean, which is attached convex surface to the periosteum of the lacrimal fossa. The gland is covered in front by the tarso-orbital fascia, and in the back it is in contact with the orbital tissue. The gland is held in place by connective tissue cords stretched between the gland capsule and the periorbita.
The orbital part of the gland is usually not palpable through the skin, since it is located behind the bony edge of the orbit that hangs here. When the gland enlarges (for example, tumor, 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, the color is grayish-red. The lobes 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 inferior 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 inverted and the eye is turned inward and downward, the lower lacrimal gland is normally visible in the form of a slight protrusion of a yellowish tuberous mass. In the case of inflammation of the gland (dacryoadenitis), a more pronounced bulge is found in this place due to swelling 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 inferior lacrimal gland is 2-2.5 times smaller than the superior 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 conjunctiva and can be palpated here.
The lobules of the lower lacrimal gland are loosely connected to each other, its ducts partly merge with the ducts of the upper lacrimal gland, some open into the conjunctival sac independently. Thus, there are a total of 10-15 excretory ducts of the upper and lower lacrimal glands.
The excretory ducts of both lacrimal glands are concentrated in one small area. Scar changes in the conjunctiva in this place (for example, with trachoma) may 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 agents entering the eye).
In normal condition, to perform all functions, 0.4-1.0 ml of tears produce small accessory lacrimal glands Krause (20 to 40) and Wolfring (3-4), embedded in the thickness of the conjunctiva, especially along its upper transitional fold. During sleep, tear secretion slows down sharply. 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.
Tear is a sterile, clear, 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, but also sodium carbonates and magnesium, calcium sulfate and phosphate).
With various emotional manifestations, the lacrimal glands, receiving additional nerve impulses, produce excess fluid that flows from the eyelids in the form of tears. There are persistent disturbances in tear secretion towards hyper- or, conversely, hyposecretion, which is often a consequence of pathology of nerve conduction or excitability. Thus, tear production decreases with paralysis of the facial nerve (VII pair), especially with damage to its geniculate ganglion; trigeminal nerve palsies (V pair), as well as in some poisonings and severe infectious diseases With high temperature. Chemical, painful temperature irritations of the first and second branches of the trigeminal nerve or zones of its innervation - conjunctiva, anterior parts of the eye, nasal mucosa, hard meninges accompanied by profuse tearing.
The lacrimal glands have sensitive and secretory (vegetative) 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 superior cervical sympathetic ganglion.
Lacrimal ducts.
They are designed to drain tear fluid from the conjunctival sac. Tear as an organic liquid ensures the normal vital activity and 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 section of the upper 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). By moving the eyelids, the tear moves along the tear stream towards 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 semilunar fold.
The lacrimal ducts themselves include lacrimal openings (punctum lacrimale), lacrimal canaliculi (canaliculi lacrimales), lacrimal sac (saccus lacrimalis), and nasolacrimal duct (ductus nasolacrimalis).
Lacrimal puncta(punctum lacrimale) are the initial openings of the entire lacrimal apparatus. Their normal diameter is about 0.3 mm. The lacrimal puncta are located at the top of small conical projections called lacrimal papillae (papilla lacrimalis). The latter are located on the posterior ribs of the free edge of both eyelids, the upper one is approximately 6 mm, and the lower one is 7 mm from their internal commissure.
The lacrimal papillae face the eyeball and are almost adjacent to it, while the lacrimal puncta are immersed in the lacrimal lake, at the bottom of which lies the lacrimal caruncle (caruncula lacrimalis). Close contact of the eyelids, and therefore the lacrimal openings with the eyeball, is facilitated by constant tension of the tarsal muscle, especially its medial sections.
The holes located at the top of the lacrimal papillae lead into the corresponding thin tubes - superior and inferior lacrimal canaliculi. They are located entirely in the thickness of the eyelids. In direction, each tubule is divided into a short oblique vertical and a longer horizontal part. The length of the vertical sections of the lacrimal canaliculi does not exceed 1.5-2 mm. They run perpendicular to the edges of the eyelids, and then the tear ducts turn towards the nose, taking a horizontal direction. The horizontal sections of the tubules are 6-7 mm long. The lumen of the lacrimal canaliculi is not the same throughout. They are somewhat narrowed in the bending area and ampullarly widened at the beginning of the horizontal section. Like many other tubular formations, the lacrimal canaliculi have a three-layer structure. The outer, adventitial membrane is composed of delicate, thin collagen and elastic fibers. The middle muscular layer is represented by a loose layer of bundles of smooth muscle cells, which apparently play a certain role in regulating the lumen of the tubules. The mucous membrane, like the conjunctiva, is lined with columnar epithelium. This arrangement of the lacrimal canaliculi allows them to stretch (for example, under mechanical influence - the introduction of conical probes).
The terminal sections of the lacrimal canaliculi, each individually or merging with each other, open into the upper section of a wider reservoir - the lacrimal sac. The mouths of the lacrimal canaliculi usually lie at the level of the medial commissure of the eyelids.
Lacrimal sac(saccus lacrimale) makes up the upper, expanded part of the nasolacrimal duct. Topographically, it relates to the orbit and is located in its medial wall in the bone recess - 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. In the downward direction, 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 submucosal layer of loose connective tissue. The inner surface of the mucous membrane is lined with multirow 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. The sac is limited medially by the periosteum of the lacrimal fossa, covered in front by the internal ligament of the eyelids and the tarsal muscle attached to it. The tarso-orbital fascia runs 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, purulent processes of the lacrimal sac extremely rarely give complications to 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 the lacrimal sac, under the skin of the internal angle, there is a large and functional important vessel- angular artery (a.angularis). It is a link between the external and internal systems carotid arteries. The angular vein is formed at the inner corner of the eye, which then continues into the facial vein.
Nasolacrimal duct(ductus nasolacrimalis) is 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. General direction channel - from top to bottom, from front to back, from outside to inside. The course of the nasolacrimal duct varies somewhat depending on the width of the back of the nose and the pyriform opening of the skull.
Between the wall of the nasolacrimal duct and the periosteum of the bone canal there is a densely branched network venous vessels, this is a continuation of the cavernous tissue of the inferior turbinate. Venous formations are especially developed around the mouth of the duct. 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 tears from moving into the nose. This phenomenon is well known to everyone as lacrimation during an acute runny nose.
The mucous membrane of the duct is lined with two-layer columnar epithelium; small branched tubular glands are found here. Inflammatory processes and 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 duct has a slit-like shape: its opening is located in the front part of the lower nasal meatus, 3-3.5 cm away from the entrance to the nose. Above this opening there is a special fold called the lacrimal fold, which represents a duplication of the mucous membrane and prevents the reverse flow of tear fluid.
In the prenatal period, the mouth of the nasolacrimal duct is closed by a connective tissue membrane, which resolves by the time of birth. However, in some cases this membrane may persist, which requires urgent measures for its removal. Delay threatens the development of dacryocystitis.
The tear fluid, irrigating the front surface of the eye, partially evaporates from it, and the excess collects in the tear lake. The mechanism of tear production 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 canaliculi, the capillary lumen of which, under the influence of the tone of their intramural muscular layer, associated with the opening of the eyelids, expands and sucks in fluid from the lacrimal lake. When the eyelids close, the canaliculi are compressed and the tear is squeezed into the lacrimal sac. Of no small importance is the suction effect of the lacrimal sac itself, which during blinking movements alternately expands and contracts due to the traction of the medial ligament of the eyelids and the contraction of 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 tear fluid through the lacrimal ducts under normal conditions lasts about 10 minutes. Approximately this amount of time is required for (3% collargol, or 1% fluorecein) from the lacrimal lake to reach the lacrimal sac (5 minutes - canalicular test) and then the nasal cavity (5 minutes - positive nasal test).
