Nerves of the levator muscle of the upper eyelid. Eyelids: structure
Superior, inferior, external and internal rectus muscles
Upper and lower obliques
Innervation is carried out by the oculomotor, trochlear and abducens nerves. The superior oblique is block-shaped. The external rectus is abducens, the rest are oculomotor.
Name three retinal neurons
External – photoreceptor
Middle – associative
Internal - ganglionic
Anatomy of the lacrimal ducts
Sl. The pathways are: lacrimal openings, lacrimal canaliculi, lacrimal sac and nasolacrimal canal.
Sl. the points are located at the medial canthus, they face the eyeball. They pass into lacrimal canaliculi, which have vertical and horizontal bends. Their length is 8-10 mm. The horizontal parts flow into the lacrimal sac on its lateral side. Sl. the bag is a cylindrical cavity closed at the top, 10-12 mm long. And with a diameter of 3-4 mm. It is located in the lacrimal fossa, it is surrounded by fascia. Below it passes into the nasolacrimal duct, which opens under the inferior nasal concha. Length 14-20 mm, width 2-2.5 mm.
Which muscle ensures tight closure of the eyelids? ITS innervation
Round muscle of the eye (orbital and palpebral parts)
Innervated – n. facialis
The levator palpebrae superioris muscle, its innervation
It starts from the periosteum of the orbit in the area of the optic foramen. The two legs of this muscle (the anterior one - to the skin of the eyelids and the eyelid bundle of the circular muscle, the posterior one - to the conjunctiva of the superior transitional fold) are innervated by the oculomotor nerve, its middle part (attached to the cartilage of the eyelids), consisting of smooth fibers, is innervated by the sympathetic nerve.
Name the structures included in the optical system of the eye. Structure and functions of the lens
Light-conducting part: cornea, anterior chamber aqueous humor, lens, vitreous body
Light-receiving section: retina.
The lens develops from the ectoderm. This is an exclusively epithelial formation, isolated from the rest of the membranes of the eye by a capsule, and does not contain nerves or blood vessels. Consists of lens fibers and a capsule capsule (the anterior part of the capsule regenerates). In the chronology There is an equator and two poles: anterior and posterior. The cortex and nucleus of the ridge are also isolated. Histologically, it consists of a capsule, capsule epithelium and fibers.
Which nerve innervates the superior oblique muscle?
Block
Name the layers of the conjunctiva
Stratified columnar epithelium
Subepithelial tissue (adenoid)
Structure and functions of the iris
Located in the frontal plane. It looks like a thin, almost round plate. Horizontal diameter 12.5 mm, vertical 12 mm. In the center is the pupil (serves to regulate the amount of light rays entering the eye). The anterior surface has radial striations and slit-like depressions (crypts). Parallel to the pupillary edge there is a serrated ridge. The iris is divided into anterior - mesodermal and posterior - ectodermal (retinal) sections.
What glands produce tears?
Mainly small accessory conjunctival glands of Krause + lacrimal gland, activated during pathological processes.
Name the three membranes of the eyeball
Fibrous
Vascular
Mesh
Name the main anatomical layers of the eyelids
Subcutaneous tissue
Circular muscle of the eyelids
Dense connective plate (cartilage)
Conjunctiva of the eyelids
30. Name the formations entering and exiting through the inferior and superior orbital fissures
Upper Ch. gap:
All oculomotor nerves
I branch of the trigeminal nerve
V. Ophthalmica sup.
Lower ch. gap:
Inferior orbital nerve
Inferior orbital vein
What is superior orbital fissure syndrome?
a combination of complete ophthalmoplegia with anesthesia of the cornea, upper eyelid and homolateral half of the forehead, caused by damage to the oculomotor, trochlear, abducens and optic nerves; observed with tumors, arachnoiditis, meningitis in the area of the superior orbital fissure. For tumors, for compression:
Exophthalmos
Midriaz
Decreased feelings. Corneas
Reduced mobility of the eyes. apple (ophthalmoplegia)
Name the sources of blood supply to the retina
The outer layers are the choroid. Internal - central retinal artery.
What are Krause's accessory lacrimal glands? Their function
Small conjunctival tissues are the main source of tears.
Sensory innervation of the choroid
35. Name the formations entering and exiting through the optic foramen
Into the orbit: a.ophthalmica; It turns out - the optic nerve
Name the sections of the conjunctiva
Eyelid, - eyeball, - transitional folds
Name the three sections of the drainage system of the human eye
Trabecula, - scleral sinus, - collector canals
What structures form the anterior chamber angle
The anterior part is the corneoscleral junction, the posterior part is the root of the iris, the apex is the ciliary body.
Ligamentous apparatus of the lens
Lens diaphragm, - hyaloid-lens ligament
PHYSIOLOGICAL OPTICS
Unit of measurement of physical refraction, its characteristics
To measure the optical power of lenses, the inverse of the focal length is used - diopter. One diopter is the refractive power of a lens with a focal length of 1 m.
Types of clinical refraction of the eye
Emmetropia
Hypermetropia
Astigmatism
What is clinical refraction
Cl. refraction is characterized by a further point of clear vision, the position of the main focus in relation to the retina.
4. Methods for determining clinical refraction
1) Subjective – selection of corrective lenses
2) Objective – refractometry, ophthalmometry, skiascopy
Name the main types of astigmatism
Correct (simple, complex, mixed)
Wrong
Back
Accommodation mechanism
When the fibers of the ciliary muscle contract, the ligament to which the encapsulated lens is suspended relaxes. The weakening of the fibers of this ligament reduces the degree of tension of the lens capsule. In this case, the lens takes on a more convex shape.
Types of optical correction of refractive errors
Contact lenses, glasses….
What is anisometropia, aniseikonia
Anisometropia – unequal refraction of both eyes
Aniseikonia - unequal size of the image of objects on the retina of both eyes
What is the anterior-posterior size of the eyeball of an adult with emmetropia?
Draw the course of parallel rays after refraction in the emmetropic eye
Draw the course of parallel rays after refraction in the myopic eye
Draw the course of parallel rays after refraction in the hypermetropic eye
What is the nearest point of clear vision. What does her position depend on?
The point closest to the eye, which is clearly visible when accommodation is at rest.
Location of the further point of clear vision in emmetrope, myope and hypermetrope
Emmetrope - at infinity
Myop – at a finite distance (only diverging rays are collected on the retina)
The hypermetrope is imaginary, lies in the negative space - behind the retina.
Which rays are focused on the retina in emmetropes, myopes, hypermetropes
Myop - scattering
Emmetrope – parallel
Hypermetrope – converging
Basic physical parameters of myopia
The refractive power does not correspond to the length of the eye - it is great
A further point of clear vision at a finite distance
Only diverging rays are collected
Main focus in front of the retina
Basic physical parameters of hypermetropia
The main focus is behind the retina, the eye has no further point of clear vision, weak refraction.
Subjective methods for studying clinical refraction
Selection of corrective lenses
19. Objective methods for determining clinical refraction
Skiascopy (shadow test)
Refractometry
Ophthalmometry
What is presbyopia? When it arises. How does it change with age?
Presbyopia is a distance from the nearest point of clear vision.
With age, the lens tissue becomes denser, therefore the accommodative ability of the eye decreases. Clinically manifested by distance from the nearest point of clear vision.
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. 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 of the upper wall of the orbit in front of the optic canal, goes forward and, near the upper edge of the orbit, passes into 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 cartilage 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 join the 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 eyelid cartilage.
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.
The eyelids, in the form of movable flaps, cover the front surface of the eyeball and perform a number of functions:
A) protective (from harmful external influences)
B) tear distribution (tears are distributed evenly during movements)
B) maintain the necessary moisture of the cornea and conjunctiva
D) wash away small foreign bodies from the surface of the eye and promote their removal
The free edges of the eyelids are about 2 mm thick and, when the palpebral fissure is closed, fit tightly to each other.
The eyelid has an anterior, slightly smoothed edge from which the eyelashes grow, and a posterior, sharper edge facing and fitting tightly to the eyeball. Along the entire length of the eyelid between the anterior and posterior ribs there is a strip of flat surface called Intermarginal space. The skin of the eyelids is very thin, folds easily, has delicate vellus hairs, sebaceous and sweat glands. The subcutaneous tissue is loose and completely devoid of fat. When the palpebral fissure is open, the skin of the upper eyelid, slightly below the superciliary arch, is pulled deeper by the fibers of the muscle that lifts the upper eyelid, which are attached to it, as a result of which a deep upper orbitopalpebral fold is formed here. A less pronounced horizontal fold is present on the lower eyelid along the lower orbital margin.
Located under the skin of the eyelids Orbicularis oculi muscle, in which the orbital and palpebral parts are distinguished. The fibers of the orbital part begin from the frontal process of the maxilla on the inner wall of the orbit and, having made a full circle along the edge of the orbit, are attached at the place of their origin. The fibers of the palpebral part do not have a circular direction and spread in an arcuate manner between the internal and external ligaments of the eyelids. Their contraction is caused by the closure of the palpebral fissure during sleep and during blinking. When you close your eyes, both parts of the muscle contract.
The internal ligament of the eyelid, starting as a dense bundle from the frontal process of the upper jaw, goes to the inner corner of the palpebral fissure, where it bifurcates and is woven into the inner ends of the cartilages of both eyelids. The posterior fibrous fibers of this ligament turn back from the internal angle and attach to the posterior lacrimal crest. As a result, a fibrous space is formed between the anterior and posterior knees of the internal ligament of the eyelids and the lacrimal bone, in which the lacrimal sac is located.
The fibers of the palpebral part, which start from the posterior knee of the ligament and, spreading through the lacrimal sac, are attached to the bone, are called the lacrimal muscle (Horner). During blinking, this muscle stretches the wall of the lacrimal sac, in which a vacuum is created, sucking tears from the lacrimal lake through the lacrimal canaliculi.
The muscle fibers that run along the edge of the eyelids, between the fibers of the eyelashes and the excretory ducts of the meibomian glands, make up the ciliary muscle (Riolan). When it is pulled, the posterior edge of the eyelid is tightly adjacent to the eye.
The orbicularis oculi muscle is innervated by the facial nerve.
Posterior to the palpebral portion of the orbicularis muscle is a dense connective plate called eyelid cartilage, although it does not contain cartilaginous cells. The cartilage serves as the skeleton of the eyelids and, due to its slight convexity, gives them the appropriate appearance. Along the orbital margin, the cartilages of both eyelids are connected to the orbital margin by the dense tarso-orbital fascia. In the thickness of the cartilage, perpendicular to the edge of the eyelid, there are meibomian glands that produce fatty secretions. Their excretory ducts exit through pinholes into the intermarginal space, where they are located in a regular row along the posterior edge of the eyelid. The secretion of meibomian gland secretion is facilitated by the contraction of the ciliary muscle.
Functions of grease:
A) prevents tears from flowing over the edge of the eyelid
B) directs the tear inwards into the lake of tears
C) protects the skin from maceration
D) retains small foreign bodies
D) when the palpebral fissure is closed, creates its complete sealing
E) participates in the formation of the capillary layer of tears on the surface of the cornea, delaying its evaporation
Along the front edge of the eyelid, eyelashes grow in two or three rows; on the upper eyelid they are much longer and there are more of them in number. Near the root of each eyelash there are sebaceous glands and modified sweat glands, the excretory ducts of which open into the hair follicles of the eyelashes.
In the intermarginal space at the inner corner of the palpebral fissure, due to the bending of the medial edge of the eyelids, small elevations are formed - lacrimal papillae, at the top of which lacrimal puncta gape with small holes - the initial part of the lacrimal canaliculi.
Attached along the superior orbital margin of the cartilage Levator superioris muscle, which starts from the periosteum in the area of the optic foramen. It runs forward along the upper wall of the orbit and, not far from the upper edge of the orbit, passes into the broad tendon. The anterior fibers of this tendon are directed to the palpebral bundle of the orbicularis muscle and to the skin of the eyelid. The fibers of the middle part of the tendon are attached to the cartilage, and the fibers of the posterior part approach the conjunctiva of the superior transitional fold. The middle part is actually the end of a special muscle consisting of smooth fibers. This muscle is located at the anterior end of the levator and is closely connected with it. Such a harmonious distribution of the tendons of the muscle that lifts the upper eyelid ensures the simultaneous lifting of all parts of the eyelid: skin, cartilage, conjunctiva of the upper transitional fold of the eyelid. Innervation: the middle part, consisting of smooth fibers, is the sympathetic nerve, the other two legs are the oculomotor nerve.
The posterior surface of the eyelid is covered with conjunctiva, tightly fused with cartilage.
The eyelids are richly supplied with vessels due to branches of the ophthalmic artery from the internal carotid artery system, as well as anastomoses from the facial and maxillary arteries from the external carotid artery system. Branching out, all these vessels form arterial arches - two on the upper eyelid and one on the lower.
Sensitive innervation of the eyelids is the first and second branches of the trigeminal nerve, motor innervation is the facial nerve.
Translated from Latin, this name has the following meaning: levare - lift, palpebral - century-old, superior - upper.
Considering its location and innervation, this muscle is usually classified as an orbital muscle. It is unusual in that it contains visceral and somatic muscle fibers, and is considered to be an antagonist of the eyelid portion of the entire orbicularis oculi muscle, causing palsy of the levator muscle to promote drooping of the eyelid over the eyeball.
Muscle that lifts the upper eyelid - functions and features
Clinical features
This muscle is striated, innervated third pair of cranial nerves. The superior tarsal muscle is very smooth and innervated by sympathetic postganglionic fibers from the cervical ganglion. In the treatment of sympathetic reflex dystrophy (Sudek's atrophy), blockade of this node will affect the drooping of the ipsilateral eyelid. When the muscle is paresis, the upper eyelid also droops. Paresis leads to ptosis.
Ptosis is a pathology in which drooping of the eyelid develops. The most common cases are unilateral ptosis, but cases of drooping eyelids on both sides are possible. When ptosis of the upper eyelid occurs from 1.5 to 2.0 mm, there is an asymmetrical position of the eyelids, which is an aesthetic problem. In severe cases of ptosis, the pupil is closed by the eyelid, which can lead to visual impairment.
Functions
- raises the eyelid;
- takes part in blinking;
- controls the width of the palpebral fissure (however, the width of the palpebral fissure is most precisely controlled by the sympathetic nervous system and tarsal muscles);
- is an active muscle when awake.
Structural features
This muscle is attached to the orbital superior edge of the cartilage. It starts from the periosteum, which is located in the area of the optic opening. It goes forward along the wall of the orbit, slightly approaching its upper edge, and neatly passes into the tendon, the width of which differs in size in a larger direction.
The anterior fibers of the tendon are attached to the cartilage and directed to the palpebral bundle of the main orbicularis oculi muscle, as well as to the skin of the eyelid itself. The fibers of the posterior part are attached to the conjunctiva of the transitional superior fold. As for the fibers of the middle part of this tendon, they are also attached to the cartilage and are the end of the muscle. The muscle itself, which raises the upper eyelid, has a close connection with the levator and is located at its anterior end. With such a harmonious distribution of tendons, the simultaneous lifting of all components of the eyelid is ensured, namely: cartilage, skin and conjunctiva transitional upper fold.
This distribution is usually called three portions of muscles. In other words, the muscle that lifts the upper eyelid provides simultaneous movement of the eyelid through cartilage (this is the middle portion), the conjunctival superior fornix (posterior portion) and skin (anterior portion).
As for the innervation, the middle part consists of fibers of distinctive smoothness and is the sympathetic nerve, while the other two legs are the oculomotor nerve.
The rear surface of the eyelid is covered with conjunctiva, which is tightly fused with cartilage.
With correct levator tone, the upper eyelid occupies a position that promotes corneal closure by 2 mm. "Lift" function may be impaired due to ptosis, and also due to the smoothness of the orbital-palpebral superior groove.
The movement of the muscle is located lateral to the superior oblique muscle and slightly superior to the rectus muscle. Anterior to the superior part of the orbit, the entire levator is surrounded by a thin layer of fatty tissue and accompanied by the superior orbital artery, trochlear and frontal nerves. These nerves separate the levator muscle from the roof of the orbit.
The rectus superioris muscle and the levator muscle of the eyelid are separated from each other quite easily, despite the fact that they are in close proximity; but not in the medial part, there they are connected by the fascial membrane. These muscles equally emerge from the mesoderm and are innervated by a branch that belongs to the oculomotor nerve. The nerve enters the muscles from below at a distance of approximately 12 mm from the apex of the orbit. The nerve trunk can also approach the levator muscle on the other side of the rectus muscle.
A small area is attached to the levator on the posterior side of the upper edge of the orbit fibrous dense tissue which supports the eyeball. This tissue is commonly called the superior transverse ligament of Withnell.
The connection between the levator and the posterior aspect of the superior edge of the orbit is very strong; in the inner and outer parts especially, this means that they can only be separated in areas located in the center.
On the medial side, the Withnell ligament ends closer to the trochlea, but still passes under the appearance of fibrous cords under the superior oblique muscle posteriorly, after which it mixes with the fascia that covers the supraorbital notch. Externally, the ligament of Withnell connects the fibrous capsule of the lacrimal gland and the periosteum of the frontal bone.
Withnell believes that the main function of his ligament is ability to limit displacement(tension) of the muscle on the back side. The author of his theory put forward this assumption, based on the localization and distribution of this function, as an analogue of the limiting ligaments of the external muscles. He thought there were similarities. By straining, the ligament helps support the upper eyelid. If it is destroyed, the levator of the eyelid will become sharply thickened and ptosis will occur inside.
From the transverse ligament to the very bottom of the cartilaginous plate, the distance is from 14 to 20 mm; from the levator aponeurosis to the skin circular insert - no more than 7 mm.
The levator aponeurosis, in addition to the palpebral insert, forms a fibrous cord (quite wide), which attaches to the edge of the orbit behind the external and internal ligaments of the eyelid. These links are called: inner "horn", outer "horn". Due to the fact that they are rigid, during the period of levator resection, the supporting function of the upper eyelid in the correct position is noted by fixing the “horn” with an additional instrument.
The external “horn” is a bundle of fibrous tissue that differs in power and in some places divides the inner part of the lacrimal gland into two parts. It is located below, attached in the area of the tubercle of the orbit from the outside to the external ligament of the eyelid. If this anatomical feature is not taken into account and, if necessary, surgery is performed to remove the tumor of the lacrimal gland, ptosis (of the lateral part of the eyelid) may occur.
The internal “horn,” on the contrary, is thin and looks like film. The location of this film is over the tendon of the superior oblique muscle, towards the internal ligament of the eyelid and towards the posterior lacrimal crest.
As for the fibers of the levator tendon of the upper eyelid, they are woven into the connective tissue of the cartilaginous plate at the third level. When the muscles contract, the eyelid rises, as a result of which the preaponeurotic eyelid shortens and the postaponeurotic eyelid lengthens.
In general, the eyelids are well vascularized by branches of the ophthalmic artery in the internal carotid artery system and anastomoses of the maxillary and facial arteries in the external carotid artery system. When these vessels branch, arterial arches are formed, one in the lower eyelid and two in the upper.
- (m. levator palpebrae superioris, PNA, BNA, JNA) see List of anat. terms... Large medical dictionary
CRYPTOPHTHALMUS- (from the Greek kryptos hidden and ophthalmos eye), a congenital malformation consisting in the fact that the eyeball is covered with skin continuously stretched over it from the cheek to the forehead. Sometimes there is a rudimentary hole in place of the palpebral fissure, sometimes... ...
Auxiliary organs- The eyeball has mobility thanks to the muscles of the eyeball (mm. bulbi). All of them, except for the inferior oblique muscle (m. obliquus inferior), come from the depths of the orbit, forming a common tendon ring (anulus tendineus communis) (Fig. 285) around... ... Atlas of Human Anatomy
Eye- an organ for the perception of light stimulation in some invertebrate animals (in particular, cephalopods), all vertebrates and humans. In most invertebrates, the function of vision is performed by less complex organs of vision, for example... ... Great Soviet Encyclopedia
Major organs- The main basic apparatus responsible for reception is the eyeball (bulbus oculi) (Fig. 283, 285). It has an irregular spherical shape and is located in the anterior part of the orbit. Most of the eyeball is hidden, and to see... ... Atlas of Human Anatomy
Facial Coding System- Muscles of the head and neck The Facial Action Coding System (FACS) is a system for classifying ... Wikipedia
LICHTENBERG- Alexander (AlexanderLich tenberg, born in 1880), an outstanding modern German. urologist. He was an assistant to Cherny and Narath. In 1924, he received the management of the urological department at the Catholic Church of St. Hedwig in Berlin, to the swarm in... ... Great Medical Encyclopedia
Reflex- I Reflex (lat. reflexus turned back, reflected) a reaction of the body that ensures the emergence, change or cessation of the functional activity of organs, tissues or the whole organism, carried out with the participation of the central nervous... ... Medical encyclopedia
Eyelids- I Eyelids (palpebrae) are auxiliary organs of the eye, looking like semicircular flaps that cover the front part of the eyeball when closed. Protect the open surface of the eye from adverse environmental influences and promote... ... Medical encyclopedia
Eye movement- Scheme of the extraocular muscles: 1. Common tendon ring 2. superior rectus muscle 3. inferior rectus muscle 4. medial rectus muscle 5. lateral rectus muscle 6. superior oblique muscle 8. inferior oblique muscle 9. levator palpebrae superioris 10.… ... Wikipedia
eyelids- (palpebrae) formations located in front of the eyeball. There are upper and lower eyelids that limit the palpebral fissure. Above the upper eyelid is the eyebrow. The eyelids are covered on the outside with skin, on the inside with conjunctiva, and in their thickness there are dense... ... Glossary of terms and concepts on human anatomy
