The front wall of the eye. Eye socket - structure and functions

31.03.2020

Table of contents of the subject "Facial Section of the Head. Region of the Orbit. Region of the Nose.":

Eye socket, orbita, is a pair of symmetrical recesses in the skull, in which the eyeball with its auxiliary apparatus is located.

Human eye sockets they have the shape of tetrahedral pyramids, the truncated tops of which are turned back to the Turkish saddle in the cavity of the skull, and the wide bases are anterior to its front surface. The axes of the orbital pyramids converge (converge) posteriorly and diverge (diverge) anteriorly.
The average size of the orbit: the depth in an adult varies from 4 to 5 cm; the width at the entrance to it is about 4 cm, and the height usually does not exceed 3.5-3.75 cm.

Walls of the orbit formed by bone plates of various thicknesses and separate the orbit:
upper wall of the orbit - from the anterior cranial fossa and frontal sinus;
lower wall of the orbit - from the maxillary paranasal sinus, sinus maxillaris ( maxillary sinus);
the medial wall of the orbit - from the nasal cavity and lateral - from the temporal fossa.

Almost at the very top of the eye sockets a rounded hole is located about 4 mm across - the beginning of the bony optic canal, canalis opticus, 5-6 mm long, used to pass the optic nerve, n. opticus, and ophthalmic artery as well. ophthalmica, into the cranial cavity.

Deep in the orbit, on the border between its upper and outer walls, next to canalis opticus, there is a large upper orbital fissure, fissura orbitalis superior, connecting the orbital cavity with the cranial cavity (middle cranial fossa). It includes:
1) optic nerve, n. ophthalmicus;
2) the oculomotor nerve, n. oculomotorius;
3) abduction nerve, n. abducens;
4) block nerve, n. trochlearis;
5) the upper and lower ophthalmic veins, w. ophthalmicae superior et inferior.

At the border between the outer and lower walls of the orbit, there is a lower orbital fissure, fissura orbitalis inferior, leading from the cavity of the orbit into the pterygo-palatine and lower temporal fossa. Pass through the lower orbital fissure:
1) the lower orbital nerve, n. infraorbitalis, together with the same artery and vein;
2) the cheekbone nerve, n. zygomaticotemporal;
3) the skulolitic nerve, n. zygomaticofacial;
4) venous anastomoses between the veins of the orbits and the venous plexus of the pterygo-palatine fossa.

On the inner wall of the eye sockets the front and rear ethmoid openings are located, which serve to pass the nerves of the same name, arteries and veins from the orbits to the labyrinths of the ethmoid bone and nasal cavity.

In the thickness of the lower wall of the orbits lies the lower orbital sulcus, sulcus infraorbitalis, passing anteriorly into the canal of the same name, opening on the front surface with a corresponding hole, foramen infraorbitale. This channel serves to pass the lower orbital nerve with the same artery and vein.

Entrance to the orbit, aditus orbitae, is bounded by the bone edges and closed by the orbital septum, septum orbitale, which separates the eyelid region and the orbit itself.

Orbital Anatomy Training Video

Anatomy of the eye socket by Professor V.A. Izranova represented.

Orbit - a confined space containing a large number of complex anatomical structures that provide vital functions and functions of the organ of vision. The close apatomo-thiographic connection of the orbit with the cranial cavity, paranasal sinuses causes the same symptoms in many, sometimes absolutely various diseases, exacerbates the course of the pathological process in the orbit (tumor, inflammatory) and, of course, presents great difficulties in conducting orbital operations.

Bone orbit represents a geometric figure close in shape to a tetrahedral pyramid, the apex of which is directed posteriorly and somewhat inwards (at an angle of 45 ° with respect to the sagittal axis). The shape of the anterior orbit may approach round, but more often the diameters in the vertical and horizontal directions vary (on average they are about 35 and 40 mm, respectively).

V.V. Valsky in the study of sizes orbits using computed tomography (CT) scan in 276 healthy individuals, it was found that the horizontal orbit diameter at the entrance is on average 32.6 mm in men and 32.7 mm in women. In the middle third, the diameter of the orbit decreases almost by half and reaches 18.2 mm in men and 16.8 mm in women. The depth of the orbit is also variable (from 42 to 50 mm). The shape can be distinguished short and wide (with such an orbit, its depth is the smallest), narrow and long orbit, at which the greatest depth is noted.

Distance from the posterior pole of the eye to the apex of the orbit in men is on average 25.6 mm, in women - 23.5 mm. Bone walls are unequal in thickness and length: the most powerful outer wall, especially closer to the edge of the orbit, the thinnest - inner and upper. The length of the outer wall on average ranges from 41.2 mm in women to 41.6 mm in men.

Outer wall formed by the zygomatic, partially frontal and large wing of the main bone. The thickest is the zygomatic bone, but in the posterior direction it becomes thinner and at the junction with the large wing of the main bone there is its thinnest section. This feature of the structure of the zygomatic bone plays big role during bone operations in orbit; a thick front surface allows you to preserve the integrity of the bone flap at the time of its fixation during resection of the wall, and in a thin area, a fracture easily occurs at the time of bone traction. The outer wall borders the temporal fossa, at the apex of the orbit - with the middle cranial fossa.

Bottom wall - the orbital surface of the maxillary bone, and the anteroposterior part is the zygomatic bone and the orbital process. In the lateral part of the lower wall near the lower orbital fissure, the infraorbital groove is located - a recess covered by a connective tissue membrane. The groove gradually passes into the bone canal, opening on the front surface of the maxillary bone 4 mm from the lower orbital edge closer to its outer border.

Through channel pass the lower orbital nerve, the same artery and vein. The thickness of the lower orbital wall is 1.1 mm. This bone septum separates the contents of the orbit from the maxillary sinus and requires very careful manipulations. In case of orbital insertion, lower subperiosteal orbitotomy, the surgeon must take into account the thickness of the lower wall in order to avoid surgical fracture of the wall.

Inner wall formed by the lacrimal bone, a paper plate, a plate of the ethmoid bone, the frontal process of the maxillary bone and the body of the main bone. The largest of them is a 0.2 mm thick paper plate that separates the orbit from the cells of the trellis labyrinth. In this section, the wall is almost vertical, which is important to take into account when separating the periosteum during subperiosteal orbitotomy or ssenteretiya of the orbit. In the front of the inner wall, the lacrimal bone bends towards the nose, there is also a recess for the lacrimal sac.

Upper wall of the orbit it is triangular in shape and is formed in the anterior and middle sections of the frontal bone, and in the posterior, by the small wing of the main bone. The orbital part of the frontal bone is thin and fragile, especially in the posterior 2/3 of it, where the wall thickness does not exceed 1 mm. In the elderly, the bone substance of the upper wall can be gradually replaced by fibrous tissue. This should be considered when preparing elderly patients for surgery. In addition, assessing the state of the upper wall of the orbit helps to develop management tactics for patients with tumor or inflammatory lesions of the orbit.

Top wall It borders the frontal sinus, which in the frontal direction can spread to the middle of the wall, and in the anteroposterior one - sometimes up to the middle third of the orbit. Throughout, the surface of the upper wall of the orbit is smooth, in the middle third of it there is concavity, in the outer and internal departments there are two recesses for the lacrimal gland (lacrimal fossa) and for the block of the superior oblique muscle.

Vertex orbits coincides with the beginning of the drip of the optic nerve, the diameter of which reaches 4 mm, and the length is 5-6 mm. Through its outer hole enters the orbit optic nerve and usually the ophthalmic artery.

The eye socket is a bone receptacle for eyeball. Through its cavity, the posterior (retrobulbar) section of which is filled with a fatty body (corpus adiposum orbitae), the optic nerve, motor and sensory nerves pass, oculomotor musclesmuscle lifting upper eyelidfascial formations blood vessels. Each eye socket has the shape of a truncated tetrahedral pyramid facing the apex toward the skull at an angle of 45 ° to the sagittal plane. In an adult, the depth of the orbit is 4-5 cm, the horizontal diameter at the entrance (aditus orbitae) is about 4 cm, and the vertical is 3.5 cm (Fig. 3.5). Three of the four walls of the orbit (except the outer) border the paranasal sinuses.

The outer, most durable and least vulnerable to diseases and injuries, the wall of the orbit is formed by the zygomatic, partly frontal bone and large wing sphenoid bone. This wall separates the contents of the orbit from the temporal fossa.

The upper wall of the orbit is formed mainly by the frontal bone, in the thickness of which, as a rule, there is a sinus (sinus frontalis), and partly (in the posterior part) - by the small wing of the sphenoid bone; bordered by the anterior cranial fossa, and this circumstance determines the severity possible complications with its damage. On the inner surface of the orbital part of the frontal bone, at its lower edge, there is a small bony protrusion (spina trochlearis), to which a tendon loop is attached. A tendon of the superior oblique muscle passes through it, which then sharply changes the direction of its course. In the upper outer part of the frontal bone there is a fossa of the lacrimal gland (fossa glandulae lacrimalis).

The inner wall of the orbit over a large extent is formed by a very thin bone plate - lam. orbitalis (papyracea) of the ethmoid bone. In front of it, a lacrimal bone with a posterior lacrimal crest and a frontal process adjoin upper jaw with anterior lacrimal crest, behind is the body of the sphenoid bone, above is part of the frontal bone, and below is part of the upper jaw and palatine bone. Between the crests of the lacrimal bone and the frontal process of the upper jaw there is a depression - the lacrimal fossa (fossa sacci lacrimalis) measuring 7x13 mm, in which the lacrimal sac (saccus lacrimalis) is located. Below this fossa passes into the nasolacrimal canal (canalis nasolacrimalis) located in the wall of the maxillary bone. It contains the nasolacrimal duct (ductus nasolacrimalis), which ends at a distance of 1.5-2 cm posterior to the anterior edge of the inferior nasal concha. Due to its fragility, the medial wall of the orbit is easily damaged even with blunt injuries with the development of emphysema (more often) and the orbit itself (less often).

The lower wall of the orbit is at the same time the upper wall of the maxillary sinus. This wall is formed mainly by the orbital surface of the upper jaw, partly also zygomatic bone and the orbital process of the palatine bone. In injuries, fractures of the lower wall are possible, which are sometimes accompanied by the omission of the eyeball and the restriction of its mobility up and out when the inferior oblique muscle is infringed. The lower wall of the orbit begins from the bone wall, a little lateral to the entrance to the nasolacrimal drip. Inflammatory and tumor processes that develop in maxillary sinuseasily spread towards the orbit.

At the top in the walls of the orbit there are several holes and crevices through which a series of large nerves and blood vessels pass into its cavity.

The bony canal of the optic nerve (canalis opticus) is 5-6 mm long. It begins in the orbit with a round hole (foramen optician) with a diameter of about 4 mm, connects its cavity with the middle cranial fossa. Through this channel, the optic nerve (n. Opticus) and the ophthalmic artery (a. Ophthalmica) enter the orbit.

Upper orbital fissure (fissura orbitalis superior). It is formed by the body of the sphenoid bone and its wings, connects the orbit with the middle cranial fossa. It is tightened by a furnace with a connective tissue film through which three main branches of the optic nerve (n. Ophthalmicus) pass through the orbit - the lacrimal, nasociliary, and frontal nerves (nn. Laerimalis, nasociliaris et frontalis), as well as the block, discharge and oculomotor nerve (nn. trochlearis, abducens and oculomolorius). Through the same gap, the superior ocular vein (n. Ophthalmica superior) leaves it. With damage to this area, a characteristic symptom complex develops: complete ophthalmoplegia, i.e., immobilization of the eyeball, ptosis of the upper eyelid, mydriasis, decreased tactile sensitivity of the cornea and skin of the eyelids, expansion of the retinal veins and small exophthalmos. However, the "syndrome of the superior orbital fissure" may not be fully expressed when not all are damaged, but only individual nerve trunks passing through this fissure.

Lower orbital fissure (fissure orbitalis inferior). It is formed by the lower edge of the large wing of the sphenoid bone and the body of the upper jaw, provides the eye socket with pterygopalatine (in the posterior half) and temporal fossa. This gap is also closed by the connective tissue membrane, into which the fibers of the orbital muscle (m. Orbitalis), innervated by the sympathetic nerve, are woven. Through it, the orbit leaves one of the two branches of the inferior ophthalmic vein (the other flows into the superior ophthalmic vein), then anastomosing with the wing by the venous plexus (et plexus venosus pterygoideus), and the lower orbital nerve and artery (na infraorbitalis), the zygomatic nerve (n. zygomaticus) and orbital branches of the pterygo-palatine ganglion (ganglion pterygopalatinum).

A round hole (foramen rotundum) is located in the large wing of the sphenoid bone. It connects the middle cranial fossa with the pterygopalatine. The second branch of the trigeminal nerve (n. Maxillaris) passes through this hole, from which the infraorbital nerve (n. Infraorbitalis) leaves in the pterygopalatine fossa, and the zygomatic nerve (n. Zygomaticus) in the inferior temporal fossa. Both nerves then penetrate into the cavity of the orbit (the first subperiosteal) through the lower orbital fissure.

CONTENT OF THE EYE

The cavity of the orbit contains:
1. eyeball;
2. fatty tissue;
3. muscles;
4. vessels;
5. nerves;
6. ligamentous apparatus.

The volume of the contents of the orbit is approximately 30 cubic meters. see (in an adult), in a child - 20 cubic meters. cm.

The orbit, or bone orbit, is the bone cavity, which is a reliable protection for the eyeball, ancillary apparatus of the eye, blood vessels and nerves. The four walls of the orbit: the upper, lower, outer and inner, are firmly interconnected.

However, each of the walls has its own characteristics. So, the outer wall is the most durable, and the inner, on the contrary, is destroyed even with blunt injuries. The peculiarity of the upper, inner and lower walls is the presence of air sinuses in the composition of their bones: the frontal sinus, the ethmoid labyrinth inside and the maxillary sinus from the bottom. Such a neighborhood quite often leads to the spread of inflammatory or tumor processes from the sinuses to the orbit. The orbit itself through numerous holes and crevices is connected to the cranial cavity, which is potentially dangerous when inflammation spreads already from the orbit to the side of the brain.

The structure of the eye socket

The shape of the orbit resembles a tetrahedral pyramid with a truncated apex, having a depth of up to 5.5 cm, a height of up to 3.5 cm and a width of the entrance to the orbit of 4.0 cm. Accordingly, the orbit has 4 walls: upper, lower, inner and outer. The outer wall is formed by a sphenoid, zygomatic and frontal bone. It separates the contents of the orbit from the temporal fossa and is the strongest wall, so that with injuries the outer wall is extremely rarely damaged.

The upper wall is formed by the frontal bone, in the thickness of which, in most cases, the frontal sinus is located, therefore, in inflammatory or tumor diseases, frontal sinusOften they extend into the orbit. Near the zygomatic process of the frontal bone there is a fossa in which the lacrimal gland is located. At the inner edge there is a notch or a bone hole - the infraorbital notch, the exit site of the infraorbital artery and nerve. Near the infraorbital notch there is a small depression - a block fossa, near which there is a block spike, to which the tendon block of the superior oblique muscle is attached, after which the muscle abruptly changes its direction of movement. The upper wall of the orbit borders on the anterior cranial fossa.

The inner wall of the orbit, for the most part, forms a thin structure - ethmoid bone. Between the anterior and posterior lacrimal crests of the ethmoid bone there is a recess — the lacrimal fossa, in which the lacrimal sac is located. Below this fossa passes into the nasolacrimal canal.

The inner wall of the orbit is the most fragile wall of the orbit, which is damaged even with blunt injuries, due to which, almost always, air enters the tissue of the eyelid or the orbit itself - the so-called emphysema develops. It is manifested by an increase in tissues in volume, and when felt, the softness of the tissues is determined with the appearance of a characteristic crunch - the movement of air under the fingers. In inflammatory processes in the region of the ethmoid sinus, they can spread quite easily into the cavity of the orbit with a pronounced inflammatory process, and if a limited abscess forms, it is called an abscess, and the common purulent process is called phlegmon. Inflammation in the eye socket can spread towards the brain, which means it is life threatening.

The lower wall is formed mainly by the upper jaw. The infraorbital groove begins from the posterior edge of the lower wall, continuing further into the infraorbital canal. The lower wall of the orbit is the upper wall of the maxillary sinus. Fractures of the lower wall often occur during injuries, accompanied by drooping of the eyeball and infringement of the lower oblique muscle with limited eye mobility up and out. With inflammation or tumors located in the sinus of the upper jaw, they also easily pass into the orbit.

The walls of the orbit have many holes through which blood vessels and nerves pass, which ensure the functioning of the organ of vision. Anterior and posterior ethmoid openings - are located between the upper and inner walls, the nerves of the same name pass through them - the branches of the nasociliary nerve, arteries and veins.

Lower orbital fissure - located deep in the orbit, closed by a connective tissue septum, which is a barrier to the spread of inflammatory processes from the orbit into the pterygopalatine fossa and vice versa. Through this slit, the orbital vein leaves the lower eye vein, which then connects with the pterygoid venous plexus and the deep facial vein, and the lower orbital artery and nerve, the zygomatic nerve and the orbital branches extending from the pterygo-venous nerve node enter the orbit.

The upper orbital fissure is also tightened with a thin connective tissue film, passing through which three branches of the optic nerve enter the orbit - the lacrimal nerve, nasociliary nerve and frontal nerve, as well as the block, oculomotor and abducent nerves, and the superior ocular vein emerges. A fissure connects the orbit to the middle cranial fossa. In case of damage in the region of the superior orbital fissure, most often injuries or tumors, a characteristic set of changes occurs, namely complete immobility of the eyeball, ptosis, mydriasis, small exophthalmos, partial decrease in the sensitivity of the skin of the upper half of the face, which occurs when nerves passing through the fissure are damaged, as well as dilated veins of the eye due to impaired venous outflow along the superior ophthalmic vein.

The visual canal is the bony canal connecting the cavity of the orbit with the middle cranial fossa. The ocular artery passes through the eye socket and the optic nerve exits. The second branch of the trigeminal nerve, the maxillary nerve, passes from the circular opening, from which the infraorbital nerve is separated in the pterygopalatine fossa, and the zygomatic nerve in the inferior temporal. A round hole connects the middle cranial fossa with the pterygopalatine.

Next to the round is an oval opening connecting the middle cranial with the infratemporal fossa. Through it passes the third branch of the trigeminal nerve - the mandibular nerve, but it does not take part in the innervation of the structures of the organ of vision.

Methods for diagnosing eye diseases

External examination with an assessment of the position of the eyeballs in the orbit, their symmetry, mobility and displacement with light pressure by fingers.
Feeling of the outer bone walls of the orbit.
Exophthalmometry to clarify the degree of displacement of the eyeball.
Ultrasound diagnosis - the detection of changes in the soft tissues of the eye socket in the immediate vicinity of the eyeball.
X-ray, cT scan, magnetic resonance imaging - methods that determine the violation of the integrity of the bone walls of the orbit, foreign bodies in the orbit, inflammatory changes and tumors.

Symptoms for eye diseases

Displacement of the eyeball relative to the normal location in the orbit: exophthalmos, enophthalmos, upward, downward displacement - occurs with injuries, inflammatory diseases, tumors, changes in blood vessels in the orbit, as well as endocrine ophthalmopathy.

Violation of the mobility of the eyeball in certain directions - is observed in the same conditions as previous violations. Swelling of the eyelids, redness of the skin of the eyelids, exophthalmos is observed in inflammatory diseases of the eye socket.

Decreased vision, even blindness, is possible with inflammatory oncological diseases eye sockets, injuries and endocrine ophthalmopathy, occurs when the optic nerve is damaged.

3.2. Eye socket ( orbita) and its contents

The orbit is the bone container for the eyeball. Through its cavity, the posterior (retrobulbar) section of which is filled with a fatty body ( corpus adiposum orbitae), the optic nerve, motor and sensory nerves, oculomotor muscles, the muscle that raises the upper eyelid, fascial formations, blood vessels pass. Each eye socket has the shape of a truncated tetrahedral pyramid facing the apex toward the skull at an angle of 45 ° to the sagittal plane. In an adult, the depth of the orbit is 4-5 cm, the horizontal diameter at the entrance ( aditus orbitae) about 4 cm, vertical - 3.5 cm (Fig. 3.5). Three of the four walls of the orbit (except the outer) border the paranasal sinuses.

This neighborhood often serves as the initial reason for the development of certain pathological processes in it, more often of an inflammatory nature. Germination of tumors originating from the ethmoid, frontal and maxillary sinuses is also possible.

The outer, most durable and least vulnerable to diseases and injuries, the wall of the orbit is formed by the zygomatic, partly frontal bone and large wing of the sphenoid bone. This wall separates the contents of the orbit from the temporal fossa.

The upper wall of the orbit is formed mainly by the frontal bone, in the thickness of which, as a rule, there is a sinus ( sinus frontalis), and partly (in the posterior part) - by the small wing of the sphenoid bone; It borders on the anterior cranial fossa, and this determines the severity of possible complications in case of damage to it. On the inner surface of the orbital part of the frontal bone, at its lower edge, there is a small bone protrusion ( spina trochlearis) to which the tendon loop is attached. A tendon of the superior oblique muscle passes through it, which then sharply changes the direction of its course. In the upper outer part of the frontal bone there is a fossa of the lacrimal gland ( fossa glandulae lacrimalis).

The inner wall of the orbit over a large extent is formed by a very thin bone plate - lam. orbitalis (papyracea) ethmoid bone. The lacrimal bone with the posterior lacrimal crest and the frontal process of the upper jaw with the anterior lacrimal crest adjoin it, the sphenoid bone body is at the back, the part of the frontal bone is at the top, and the part of the upper jaw and palatine is at the bottom. Between the crests of the lacrimal bone and the frontal process of the upper jaw there is a recess - the lacrimal fossa ( fossa sacci lacrimalis) 7x13 mm in size, in which there is a lacrimal sac ( saccus lacrimalis) Below this fossa passes into the nasolacrimal canal ( canalis nasolacrimalis) located in the wall of the maxillary bone. It contains the nasolacrimal duct ( ductus nasolacrimalis), which ends at a distance of 1.5-2 cm posterior to the front edge of the lower turbinate. Due to its fragility, the medial wall of the orbit is easily damaged even with blunt injuries with the development of emphysema (more often) and the orbit itself (less often). In addition, the pathological processes that occur in the ethmoid sinus spread quite freely towards the orbit, resulting in the development of inflammatory edema of its soft tissues (cellulite), phlegmon or optic neuritis.

The lower wall of the orbit is at the same time the upper wall of the maxillary sinus. This wall is formed mainly by the orbital surface of the upper jaw, partly also by the zygomatic bone and the orbital process of the palatine bone. In injuries, fractures of the lower wall are possible, which are sometimes accompanied by the omission of the eyeball and the restriction of its mobility up and out when the inferior oblique muscle is infringed. The lower wall of the orbit begins from the bone wall, a little lateral to the entrance to the nasolacrimal drip. Inflammatory and neoplastic processes that develop in the maxillary sinus spread quite easily towards the orbit.