The structure of the eye socket. Anatomy of the orbit: structure, functions Upper wall of the orbit

Eye socket , orbita, (Fig. , ; see Fig. , ), is a four-sided cavity, the walls of which form an irregular pyramid. The orbital cavity contains the eyeball with its muscles, vessels and nerves, as well as the lacrimal gland and adipose tissue. Anteriorly, the cavity opens with a wide entrance to the orbit, aditus orbitae, which is like the base of a pyramid limited by the orbital edge, margo orbitalis, (see fig. , ). At the very entrance, the cavity of the orbit widens, and towards the back it gradually narrows. The longitudinal axes of both orbits, drawn from the middle of the entrance to them to the middle of the optic canal, converge in the area of ​​the sella turcica. The orbit borders medially with the nasal cavity, above - with the corresponding part of the anterior cranial fossa, outside - with the temporal fossa, below - with the maxillary sinus.

The entrance to the orbital cavity has the outline of a quadrangle with rounded corners. From above, the entrance is limited by the supraorbital margin, margo supraorbitalis, which is formed by the edge of the frontal bone of the same name and its zygomatic process. On the inside, the entrance to the orbit is limited by the medial edge, margo medialis, formed by the nasal part of the frontal bone and the frontal process of the maxilla. From below, the entrance to the orbit is formed by the infraorbital margin, margo infraorbitalis) upper jaw and adjacent part of the zygomatic bone.

Lateral edge margo lateralis, the entrance to the orbit is formed by the zygomatic bone. All walls of the orbit are smooth.

Upper wall, paries superior, is formed by the orbital part of the frontal bone, and its posterior section by the small wings of the sphenoid bone. The sphenoid-frontal suture runs between these two bones, sutura sphenofrontalis. At the root of each small wing there is an optic canal, canalis opticus, through which the optic nerve and ophthalmic artery pass. At the anterior edge of the upper wall, closer to its lateral corner, there is a fossa of the lacrimal gland, fossa glandulae lacrimalis, and anteriorly and inwardly from the edge is the trochlear fossa, fovea trochlearis, and trochlear spine, spina trochlearis.

Lateral wall of the orbit, paries lateralis orbitae, formed in the posterior section by the orbital surface of the greater wing of the sphenoid bone, in the anterior section by the orbital surface of the zygomatic bone. The sphenoid-zygomatic suture runs between these bones, sutura sphenozygomatica. The superior and lateral walls are separated from each other by the superior orbital fissure, fissura orbitalis superior, which is located between the large and small wings of the sphenoid bone. On the orbital surface of the zygomatic bone there is a zygomatic orbital foramen, foramen zygomaticoorbitale.

The lower wall of the orbit, paries inferior orbitae, is formed mainly by the orbital surface of the upper jaw, as well as part of the orbital surface of the zygomatic bone and the orbital process of the palatine bone. Between the lower edge of the orbital surface of the greater wing and the posterior edge of the orbital surface of the upper jaw is the lower orbital fissure, fissura orbitalis inferior, reaching the anterior end to the zygomatic bone. Through this gap the orbital cavity communicates with the pterygopalatine and infratemporal fossae. On the lateral edge of the orbital surface of the upper jaw, the infraorbital groove begins, sulcus infraorbitalis which passes into the infraorbital canal, canalis infraorbitalis, lying in the thickness of the anterior sections of the lower wall of the orbit.

Medial wall of the orbit, paries medialis orbitae, (see Fig.), is formed (from front to back) by the lacrimal bone, the orbital plate of the ethmoid bone and the lateral surface of the body of the sphenoid bone. In the anterior part of the wall there is a tear groove, sulcus lacrimalis, continuing into the fossa of the lacrimal sac, fossa sacci lacrimalis. The latter passes downwards into the nasolacrimal canal, canalis nasolacrimalis.

There are two openings along the upper edge of the medial wall of the orbit: the anterior ethmoidal foramen, foramen ethmoidae anterius, at the anterior end of the frontoethmoidal suture, and the posterior ethmoidal foramen, foramen ethmoidae posterius, near the rear end of the same seam. All the walls of the orbit converge at the optic canal, which connects the orbit to the cranial cavity. The walls of the orbit are covered with thin periosteum.

The orbit is an irregularly shaped cavity in the skull, resembling a pyramid. It is based on bone, around which ligaments, muscular apparatus, and fascial membranes are located. The eye is located directly in the orbital cavity, which is protected by all these structures from possible damage. It should be taken into account that if the impact force is very large, then even the inert orbital frame is not able to protect the eyeball from damage.

Structure of the eye socket

The orbit contains the following bones of the skull:

• Wedge-shaped;
• Zygomatic;
• Process of the frontal;
• Upper jaw;
• Ethmoid bone.

The strongest wall, in the formation of which thick bones take part, is the outer one. The thinnest wall is the inner one, which is why it is most often damaged.

Among the anatomical formations of the orbit are:

1. the fossa in which the lacrimal sac is located. It is located on the inner wall of the orbit.
2. The nasolacrimal duct extends from the lacrimal fossa.
3. The supraorbital notch through which the nerves and vessels that innervate and supply the eye pass into the orbital cavity. It is located along the upper edge of the orbit.
4. Lateral spine located next to the supraorbital notch. The superior oblique muscle is attached to it.
5. The infraorbital groove, which continues into the canal, is located in the region of the lower wall of the orbit.
6. The orbital fissures (upper and lower), covered with a connective tissue membrane, are the entrance gates for blood vessels and nerves.

Physiological role of the orbit

Among the main functions that the orbit performs are:

• Protective, helping to keep the eyeball intact.
• Restrictive for inflammatory infiltrates.
• Connecting to the middle cranial fossa through the orbital canal and optic nerve.

Video about the structure of the eye socket

Symptoms of eye socket diseases

Symptoms of pathology of the orbital region can be quite varied:

• Restricted eye mobility;
• Dislocation of the eyeball within the orbit;
• Swelling of the area;
• Significant and sudden decrease in vision;
• Appearance of eyelid skin.

Dislocation of the eyeball within the orbit is of several types:

• Bugeye();
• Retraction (enophthalmos);
• Dislocation up or down.

Methods for diagnosing diseases of the orbit

To diagnose pathological changes in the orbit, several methods are used:

1. Visual examination, which allows you to establish the location of the eye and other indirect signs of the disease.
2. Palpation of accessible bone formations of the orbit.
3. Exophthalmometry allows you to determine the deviation of the eye forward or backward, which is important in the diagnosis of enophthalmos and bulging eyes.
4. examination of the musculoskeletal system, as well as the eye itself, which allows us to determine the degree of its involvement in the pathological process.
5. X-ray and CT scan, which help clarify the diagnosis.
6. A biopsy is performed if a tumor is suspected and allows one to evaluate the cellular composition of the material.

Let us remember once again that the orbit is the bone protection for the eyeball. In addition to bones, its composition includes muscles, ligaments, and connective tissue. The function of the orbit is not limited to protecting the eye; it also acts as a connecting link, which is made possible by transmitting information along nerve fibers.

Diseases of the eye socket

The orbit itself can be susceptible to various pathological processes, including:

• Traumatic changes that cause bone fractures.
• Tumors of benign and malignant nature.
• Emphysema of the eyelid, associated with the entry of air bubbles into the subcutaneous tissue, which occurs when the inner wall of the orbit is damaged.
• Inflammatory changes.
• Endocrine ophthalmopathy, in most cases the result of thyroid dysfunction.

Most often, the orbit undergoes inflammatory changes. Among such pathologies, the following nosologies can be distinguished:

• Orbital cellulitis is accompanied by damage to adipose tissue. The inflammation process is not localized, and therefore there is a high risk of it spreading to the eyes.
• An abscess in the orbit is a localized source of purulent infection.
• associated with inflammation of muscle fibers.
• Vasculitis is a consequence of vascular damage in this area.
• Sarcoidosis is accompanied by the formation of specific nodules and is often associated with autoimmune processes.
• Dacryoadenitis is an inflammation.
• Wegener's lymphogranulomatosis is a specific inflammatory vascular disease.

The orbit (orbita) is a paired bony cavity in the facial part of the skull, localized on the sides of the root of the nose. Three-dimensional reconstructions of the orbit are more reminiscent of a pear than the tetrahedral pyramid traditionally mentioned in textbooks, which also loses one face at the apex of the orbit.

The axes of the orbital pyramids converge posteriorly and, accordingly, diverge anteriorly, while the medial walls of the orbit are located almost parallel to each other, and the lateral ones are at right angles to each other. If we take the optic nerves as reference points, then the divergence angle of the visual axes normally does not exceed 45º, and between the optic nerve and the visual axis - 22.5º, which is clearly visible on axial computed tomograms.

The angle of divergence of the visual axes determines the distance between the eye sockets - the interorbital distance, which is understood as the distance between the anterior lacrimal ridges. This is the most important element of facial harmony. Normally, the interorbital distance in adults varies from 18.5 mm to 30.7 mm, ideally being 25 mm. Both reduced (stenopia) and increased (euryopia) interorbital distance indicates the presence of serious craniofacial pathology.

The length of the anterior-posterior axis (“depth”) of the orbits in an adult is on average 45 mm. Therefore, all manipulations in the orbit (retrobulbar injections, subperiosteal separation of tissue, the size of implants introduced to replace bone defects) should be limited to 35 millimeters from the bony edge of the orbit, not reaching at least one centimeter to the optic canal (canalis opticus). It should be borne in mind that the depth of the orbit can vary within significant limits, the extreme options of which are “deep narrow” and “shallow wide” orbits.

The volume of the orbital cavity (cavitas orbitalis) is somewhat smaller than is commonly believed and amounts to 23–26 cm 3, of which only 6.5–7 cm 3 is in the eyeball. In women, the orbital volume is 10% less than in men. Ethnicity has a great influence on orbital parameters.

Edges of the entrance to the orbit

The edges (supraorbital - margo supraorbitalis, infraorbital - margo infraorbitalis, lateral - margo lateralis, medial - margo medialis) of the orbit constitute the so-called “external orbital frame”, which plays an important role in ensuring the mechanical strength of the entire orbital complex and is part of a complex system of facial buttresses or “stiffening ribs” that dampen deformations of the facial skeleton during chewing, as well as in case of craniofacial injuries. In addition, the profile of the orbital margin plays an important role in shaping the contour of the upper and middle third of the face.

It should be noted that the edges of the orbit do not lie in the same plane: the lateral edge is shifted posteriorly compared to the medial, and the lower compared to the upper, forming a spiral with right angles. This provides a wide field of vision and gaze from below to outside, but leaves the anterior half of the eyeball unprotected from the effects of a wounding agent moving on the same side. The spiral of the entrance to the orbit is open in the area of ​​the medial edge, where it forms the fossa of the lacrimal sac, fossa sacci lacrimalis.

The continuity of the supraorbital edge at the border between the middle and inner third is broken by the supraorbital notch (incisura supraorbitalis), through which the artery, vein and nerve of the same name extend from the orbit to the forehead and sinus (a., v. et n. supraorbitalis). The shape of the tenderloin is very variable, its width is approximately 4.6 mm, height - 1.8 mm.

In 25% of cases (and in the female population - up to 40%), instead of a bone notch, there is a hole (foramen supraorbitale) or a small bone canal through which the specified neurovascular bundle passes. The hole dimensions are usually smaller than the notches and are 3.0x0.6 mm.

• Infraorbital margin (margo infraorbitalis) , formed by the upper jaw and zygomatic bone, has less strength, therefore, in case of blunt trauma, the orbit is subjected to a transient wave-like deformation, transmitted to the lower wall and causing an isolated (“explosive”) fracture with displacement of the lower muscle complex and fatty tissue into the maxillary sinus. In this case, the infraorbital margin most often remains intact.
• Medial edge of the orbit (margo medialis) in its upper part it is formed by the nasal part of the frontal bone (pars nasalis ossis frontalis). The lower part of the medial margin consists of the posterior lacrimal crest of the lacrimal bone and the anterior lacrimal crest of the maxilla.
• The most durable are lateral and supraorbital margins (margo lateralis et supraorbitalis) , formed by thickened edges of the zygomatic and frontal bones. As for the supraorbital edge, it is important
  An additional factor in its mechanical strength is the well-developed frontal sinus, which dampens shock to this area.

Walls of the orbit

Top wall

Top wall 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 section) for 1.5 cm - by the small wing of the sphenoid bone;

Similar to the lower and lateral walls, it has a triangular shape.

It borders on the anterior cranial fossa, and this circumstance determines the severity of possible complications in case of its damage. Between these two bones there is a sphenoid-frontal suture, sutura sphenofrontalis.

At the root of each lesser wing there is an optic canal, canalis opticus, through which the optic nerve and ophthalmic artery pass.

On the side, at the base of the zygomatic process of the frontal bone, directly behind the supraorbital margin there is a small depression - the fossa of the lacrimal gland (fossa glandulae lacrimalis), where the gland of the same name is located.

More medially, 4 mm from the supraorbital margin, there is a trochlear fossa (fossa trochlearis), next to which there is often a trochlear spine (spina trochlearis), which is a small bony protrusion near the transition of the upper wall to the medial one. A tendon (or cartilaginous) loop is attached to it, through which the tendon part of the superior oblique muscle of the eye passes, sharply changing its direction here.

Damage to the block due to injuries or surgical interventions (in particular, during operations on the frontal sinus) entails the development of painful and persistent diplopia due to dysfunction of the superior oblique muscle.

Inner wall

The longest (45 mm) medial wall of the orbit (paries medialis) is formed (in the anteroposterior direction) by the frontal process of the maxilla, the lacrimal and ethmoid bones, as well as the small wing of the sphenoid bone. Its upper border is the frontoethmoidal suture, the lower border is the ethmoidomaxillary suture. Unlike other walls, it has the shape of a rectangle.

The basis of the medial wall is the orbital (which they stubbornly continue to call “paper”) plate of the ethmoid bone measuring 3.5-5.0 × 1.5-2.5 cm and only 0.25 mm thick. It is the largest and weakest component of the medial wall. The orbital plate of the ethmoid bone is slightly concave, so the maximum width of the orbit is not noted in the plane of its entrance, but 1.5 cm deeper. As a consequence, percutaneous and transconjunctival approaches to the medial wall of the orbit with great difficulty provide an adequate view of its entire area.

The orbital plate consists of approximately 10 honeycombs, separated by partitions (septa) into anterior and posterior parts. Large and numerous small partitions between the ethmoidal cells (cellulae ethmoidales) strengthen the medial wall on the side of the nose, serving as buttresses. Therefore, the medial wall turns out to be stronger than the lower one, especially with a branched system of ethmoidal septa and the relatively small size of the orbital plate.

In 50% of the orbits, the ethmoidal labyrinth reaches the posterior lacrimal crest, and in another 40% of cases, the frontal process of the maxilla. This anatomical variant is called "presentation of the ethmoid labyrinth".

At the level of the frontal-ethmoidal suture, 24 and 36 mm behind the anterior lacrimal crest, in the medial wall of the orbit there are anterior and posterior ethmoidal openings (foramina ethmoidalia anterior et posterior), leading into the canals of the same name, which serve to pass from the orbit into the ethmoidal cells and cavity the nose of the same branches of the ophthalmic artery and the nasociliary nerve. It should be emphasized that the posterior ethmoidal foramen is located on the border of the superior and medial walls of the orbit in the thickness of the frontal bone, only 6 mm from the optic foramen (mnemonic rule: 24-12-6, where 24 is the distance in mm from the anterior lacrimal crest to the anterior ethmoidal foramen , 12 - the distance from the anterior ethmoidal opening to the posterior one, and, finally, 6 - the distance from the posterior ethmoidal opening to the optic canal). Exposure of the posterior ethmoidal foramen during subperiosteal separation of the orbital tissue clearly indicates the need to stop further manipulations in this area in order to avoid injury to the optic nerve.

The most important formation of the medial wall of the orbit is the 13x7 mm fossa of the lacrimal sac, located mostly in front of the tarso-orbital fascia, formed by the anterior lacrimal crest of the frontal process of the maxilla and the lacrimal bone with its posterior lacrimal crest.

The lower part of the fossa smoothly passes into the bone nasolacrimal canal (canalis nasolacrimalis), 10-12 mm long, passing through the thickness of the upper jaw and opening into the lower nasal passage 30-35 mm from the external opening of the nose.

The medial wall of the orbit separates the orbit from the nasal cavity, ethmoidal labyrinth and sphenoid sinus. This circumstance is of great clinical importance, since these cavities are often a source of acute or chronic inflammation, spreading per contuitatem to the soft tissues of the orbit. This is facilitated not only by the insignificant thickness of the medial wall, but also by the natural (anterior and posterior ethmoidal) openings in it. In addition, congenital dehiscences are often found in the lacrimal bone and orbital plate of the ethmoid bone, which are a variant of the norm, but serve as an additional gateway to infection.

Lateral wall

Lateral wall (paries lateralis) is the thickest and most durable, it is formed in its anterior half by the zygomatic bone, and in the posterior half by the orbital surface of the greater wing of the sphenoid bone. The length of the lateral wall from the edge of the orbit to the superior orbital fissure is 40 mm.

The anterior boundaries of the lateral wall are the frontozygomatic (sutura frontozygomatica) and zygomaticomaxillary (sutura zygomaticomaxillaris) sutures, and the posterior boundaries are the superior and inferior orbital fissures.

The central third - trigone (triangle or wedge-scaly suture, sutura sphenosquamosa) is highly durable. This triangle separates the orbit from the middle cranial fossa, thereby participating in the formation of both the lateral orbital wall and the base of the skull. This circumstance should be taken into account when performing an external orbitotomy, remembering that the distance from the lateral edge of the orbit to the middle cranial fossa is on average 31 mm.

The lateral wall of the orbit separates its contents from the temporal and pterygopalatine fossae, and in the area of ​​the apex - from the middle cranial fossa.

Bottom wall

Inferior wall of the orbit being the “roof” of the maxillary sinus, it is formed mainly by the orbital surface of the body of the upper jaw, in the anterior-outer section - by the zygomatic bone, in the posterior section - by a small orbital process of the perpendicular plate of the palatine bone. The area of ​​the lower orbital wall is approximately 6 cm 2, its thickness does not exceed 0.5 mm, it is the only one in the formation of which the sphenoid bone does not take part.

The lower wall of the orbit has the shape of an equilateral triangle. It is the shortest (about 20 mm) wall, not reaching the apex of the orbit, but ending with the inferior orbital fissure and the pterygopalatine fossa. A line running along the inferior orbital fissure forms the outer border of the floor of the orbit. The internal border is defined as the anterior and posterior continuation of the ethmoid-maxillary suture.

The thinnest part of the orbital floor is the infraorbital groove, which crosses it approximately in half and passes anteriorly into the canal of the same name. The back part of the inner half of the bottom wall is slightly stronger. Its remaining sections are very resistant to mechanical stress. The thickest point is the junction of the medial and inferior orbital walls, supported by the medial wall of the maxillary sinus.

The lower wall has a characteristic S-shaped profile, which must be taken into account when forming titanium implants to replace defects in the floor of the orbit. Giving the reconstructed wall a flat profile will lead to an increase in orbital volume and preservation of enophthalmos in the postoperative period.

The fifteen-degree elevation of the inferior orbital wall toward the apex of the orbit and its complex profile protect the surgeon from inadvertently inserting a rasp into the deep parts of the orbit and make direct damage to the optic nerve unlikely during reconstruction of the orbital floor.

In case of injury, fractures of the lower wall are possible, which are sometimes accompanied by drooping of the eyeball and limitation of its upward and outward mobility when the inferior oblique muscle is pinched.

Three of the four walls of the orbit (except the outer one) border the paranasal sinuses. This neighborhood often serves as the initial cause of the development of certain pathological processes in it, most often of an inflammatory nature. It is also possible for tumors to grow from the ethmoid, frontal and maxillary sinuses.

Orbital sutures

The orbital surface of the greater wing of the sphenoid bone (facies orbitalis alae majoris ossis sphenoidalis) is unequal in thickness. The anterolateral third, which connects to the orbital surface of the zygomatic bone through the sphenozygomatic suture (sutura sphenozygomatica), and the posteromedial third, which forms the lower border of the superior orbital fissure, are relatively thin. Therefore, the area of ​​the sphenoid-zygomatic suture is convenient for external orbitotomy.

Near sphenoid-frontal suture (sutura sphenofrontalis) in the large wing of the sphenoid bone at the anterior edge of the superior orbital fissure there is a non-permanent opening of the same name containing a branch of the lacrimal artery - the recurrent meningeal artery (anastomosis between a. meningea media from the basin of the external carotid artery and the ophthalmic artery from the basin of the internal carotid artery).

Sphenozygomatic The suture, due to its length and three-dimensional structure, plays an extremely important role in the process of repositioning the zygomatic bone in zygomatic-orbital fractures.

Frontozygomatic suture (sutura frontozygomatica) provides rigid fixation of the zygomatic bone to the frontal bone.

Frontoethmoidal suture is considered an important identification point marking the upper boundary of the ethmoid labyrinth. Accordingly, an osteotomy above the fronto-ethmoid suture is fraught with damage to the dura mater of the brain (DTM) in the frontal lobe.

Zygomaticofacial (canalis zygomaticofacialis) and zygomaticotemporal (canalis zygomaticotemporalis) canals contain arteries and nerves of the same name, emerging from the cavity of the orbit through its lateral wall and ending in the zygomatic and temporal regions. Here they may turn out to be an “unexpected” find for the surgeon who is separating the temporalis muscle during an external orbitotomy.

11 mm below the frontozygomatic suture and 4-5 mm behind the orbital margin is the external orbital tubercle (tuberculum orbitale Whitnall) - a small elevation of the orbital edge of the zygomatic bone, found in 95% of people. The following are attached to this important anatomical point:

• fixing ligament of the lateral rectus muscle (tendon stretch, lacertus musculi recti lateralis, sentinel ligament according to the terminology of V. V. Vita);
• suspensory ligament of the lower eyelid (inferior transverse ligament of Lockwood, Lockwood);
• lateral ligament of the eyelids;
• lateral horn of the aponeurosis of the muscle that lifts the upper eyelid;
• orbital septum (tarso-orbital fascia);
• fascia of the lacrimal gland.

Communication with cranial cavities

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

The inferior orbital fissure is located between the lateral and inferior walls of the orbit and leads into the pterygopalatine and infratemporal fossa. Through it, one of the two branches of the inferior ophthalmic vein emerges from the orbit (the second flows into the superior ophthalmic vein), anastomosing with the pterygoid venous plexus, and also includes the infraorbital nerve and artery, the zygomatic nerve and the orbital branches of the pterygopalatine ganglion.

The medial wall of the orbit, paries medians orbitae, is formed (from front to back) by the lacrimal bone, the orbital plate of the ethmoid bone and the lateral surface of the body of the sphenoid bone. In the anterior part of the wall there is a lacrimal groove, sulcus lacrimalis, which continues into the fossa of the lacrimal sac, fossa sacci lacrimalis. The latter passes downwards into the nasolacrimal canal, canalis nasolacrimalis.
There are two openings along the upper edge of the medial wall of the orbit: the anterior ethmoidal opening, foramen ethmoidale anterius, at the anterior end of the frontoethmoidal suture, and the posterior ethmoidal opening, foramen ethmoidale posterius, near the posterior end of the same suture. All the walls of the orbit converge at the optic canal, which connects the orbit to the cranial cavity. The walls of the orbit are covered with thin periosteum.

Through the superior orbital fissure leading into the middle cranial fossa, the oculomotor ( n. oculomotorius), abductor ( n. abducens) and block-shaped ( n. trochlearis) nerves, as well as the first branch of the trigeminal nerve ( r. ophthalmicus n. trigemini). The superior ophthalmic vein, which is the main venous collector of the orbit, also passes here.

The longitudinal axes of both orbits, drawn from the middle of the entrance to them to the middle of the optic canal, converge in the area of ​​the sella turcica.

Holes and fissures of the orbit:

1. Bone canal optic nerve ( canalis opticus) 5-6 mm long. 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. The optic nerve enters the orbit through this canal ( n. opticus) and ophthalmic artery ( a. ophthalmica).
2. Superior orbital fissure (fissura orbitalis superior). Formed by the body of the sphenoid bone and its wings, it connects the orbit with the middle cranial fossa. Covered with a thick connective tissue film, through which the three main branches of the optic nerve pass into the orbit ( n. ophthalmicus) - lacrimal, nasociliary and frontal nerves ( nn. laerimalis, nasociliaris et frontalis), as well as the trunks of the trochlear, abducens and oculomotor nerves ( nn. trochlearis, abducens and oculomolorius). The superior ophthalmic vein leaves it through the same gap ( n. ophthalmica superior). When this area is damaged, a characteristic symptom complex develops - “superior orbital fissure syndrome”, however, it may not be fully expressed when not all, but only individual nerve trunks passing through this fissure are damaged.
3. Inferior orbital fissure (fissuga orbitalis inferior). Formed by the lower edge of the large wing of the sphenoid bone and the body of the upper jaw, it provides communication between the orbit and the pterygopalatine (in the posterior half) and temporal fossae. This gap is also closed by a connective tissue membrane into which the fibers of the orbital muscle are woven ( m. orbitalis), innervated by the sympathetic nerve. Through it, one of the two branches of the inferior ophthalmic vein leaves the orbit (the other flows into the superior ophthalmic vein), which then anastomoses with the pterygoid venous plexus ( et plexus venosus pterygoideus), and includes the inferior orbital nerve and artery ( n. a. infraorbitalis), zygomatic nerve ( n.zygomaticus) and orbital branches of the pterygopalatine ganglion ( ganglion pterygopalatinum).
4. Round hole (foramen rotundum) is located in the greater wing of the sphenoid bone. It connects the middle cranial fossa with the pterygopalatine fossa. The second branch of the trigeminal nerve passes through this foramen ( n. maxillaris), from which the infraorbital nerve departs in the pterygopalatine fossa ( n. infraorbitalis), and in the inferotemporal - the zygomatic nerve ( n. zygomaticus). Both nerves then enter the orbital cavity (the first is subperiosteal) through the inferior orbital fissure.
5. Lattice holes on the medial wall of the orbit ( foramen ethmoidae anterius et posterius), through which the nerves of the same name (branches of the nasociliary nerve), arteries and veins pass.
6. Oval hole located in the large wing of the sphenoid bone, connecting the middle cranial fossa with the infratemporal fossa. The third branch of the trigeminal nerve passes through it ( n. mandibularis), but it does not take part in the innervation of the organ of vision.

Anatomical structures of the orbit

The orbit is the bony container for the eyeball. Through its cavity, the posterior (retrobulbar) section of which is filled with a fatty body ( corpus adiposum orbitae), pass through the optic nerve, motor and sensory nerves, oculomotor muscles, the muscle that lifts the upper eyelid, fascial formations, and blood vessels.

In front (with the eyelids closed), the orbit is limited by the tarso-orbital fascia, which is woven into the cartilage of the eyelids and fuses with the periosteum along the edge of the orbit.

The lacrimal sac is located anterior to the tarso-orbital fascia and is located outside the orbital cavity.

Behind the eyeball at a distance of 18-20 mm from its posterior pole there is a ciliary ganglion ( ganglion ciliare) size 2 x 1 mm. It is located under the external rectus muscle, adjacent in this area to the surface of the optic nerve. The ciliary ganglion is a peripheral nerve ganglion, the cells of which through three roots ( radix nasociliaris, oculomotoria et sympathicus) are connected with the fibers of the corresponding nerves.

The bony walls of the orbit are covered with a thin but strong periosteum ( periorbita), which is tightly fused with them in the area of ​​bone sutures and the optic canal. The opening of the latter is surrounded by a tendon ring ( annulus tendineus communis Zinni), from which all oculomotor muscles begin, with the exception of the inferior oblique. It originates from the lower bony wall of the orbit, near the inlet of the nasolacrimal canal.

In addition to the periosteum, the orbital fascia, according to the International Anatomical Nomenclature, includes the eyeball sheath, muscular fascia, orbital septum and orbital fat pad ( corpus adiposum orbitae).

Vagina of the eyeball ( vagina bulbi, former name - fascia bulbi s. Tenoni) covers almost the entire eyeball, with the exception of the cornea and the exit point of the optic nerve. The greatest density and thickness of this fascia are observed in the area of ​​the equator of the eye, where the tendons of the extraocular muscles pass through it on the way to the places of attachment to the surface of the sclera. As the limbus approaches, the vaginal tissue becomes thinner and is eventually gradually lost into the subconjunctival tissue. In places where they are crossed by extraocular muscles, it gives them a fairly dense connective tissue coating. Dense strands also extend from the same zone ( fasciae musculares), connecting the vagina of the eye with the periosteum of the walls and edges of the orbit. Overall, these cords form a ring-shaped membrane that is parallel to the equator of the eye and holds it in a stable position in the orbit.

Subvaginal space of the eye (formerly called spatium Tenoni) is a system of cracks in loose episcleral tissue. It ensures free movement of the eyeball to a certain extent. This space is often used for surgical and therapeutic purposes (performing implantation-type sclero-strengthening operations, administering medications by injection).

Orbital septum (septum orbitale) - a well-defined fascial-type structure located in the frontal plane. Connects the orbital edges of the cartilage of the eyelids with the bony edges of the orbit. Together they form, as it were, its fifth, movable wall, which, when the eyelids are closed, completely isolates the cavity of the orbit. It is important to keep in mind that in the area of ​​the medial wall of the orbit, this septum, which is also called the tarso-orbital fascia, is attached to the posterior lacrimal crest of the lacrimal bone, as a result of which the lacrimal sac, which lies closer to the surface, is partially located in the preseptal space, i.e. outside the cavity eye sockets.

The orbital cavity is filled with a fatty body ( corpus adiposum orbitae), which is enclosed in a thin aponeurosis and penetrated by connective tissue bridges dividing it into small segments. Due to its plasticity, adipose tissue does not interfere with the free movement of the extraocular muscles passing through it (during their contraction) and the optic nerve (during movements of the eyeball). The fat body is separated from the periosteum by a slit-like space.

CT and MR anatomy

The bony walls of the orbits are clearly visualized on CT sections, forming the shape of a truncated cone with its apex facing the base of the skull. It should be taken into account that the computer integrated into the tomograph is not able to construct an image of bone structures less than 0.1 mm thick.

Therefore, in some cases, images of the medial, lower and upper walls of the orbit are intermittent, which can mislead the doctor. The small size of the bone “defect,” the absence of angular displacements of the edges of the “fracture,” and the disappearance of discontinuity of the contour on subsequent sections make it possible to distinguish such artifacts from a fracture.

Due to the low content of hydrogen protons, the bone walls of the orbits are characterized by a pronounced hypointense signal on T1- and T2-weighted images and are poorly distinguishable on MRI.

Fat body of the orbit is clearly visualized both on CT (density 100 NU) and MRI, where it gives a hyperintense signal on T2 and low on T1-weighted images.

Optic nerve on CT scan it has a density of 42–48 HU. On ultrasound it is visualized as a hypoechoic strip. MRI allows you to trace the optic nerve along its entire length, right up to the chiasm. The axial and sagittal planes with fat suppression are especially effective for visualizing it throughout its entire length. The subarachnoid space surrounding the optic nerve is better visualized on fat-suppressed T2WI in the coronal plane.

The thickness of the optic nerve on the axial section ranges from 4.2±0.6 to 5.5±0.8 mm, which is due to its S-shaped bend and apparent (!) thickening when entering the scanning plane and “thinning” when exiting her.

Eyeball membranes with ultrasound and CT they are visualized as a single whole. The density is 50-60 NU. With MRI, they can be differentiated by the intensity of the MR signal. The sclera has a hypointense signal on T1- and T2-weighted images and appears as a clear dark stripe; the choroid and retina are hyperintense on T1-weighted and proton density-weighted tomograms.

Extraocular muscles on MR tomograms, the signal intensity differs significantly from the retrobulbar tissue, as a result of which they are clearly visualized along the entire length. On CT scan they have a density of 68-75 HU. The thickness of the superior rectus muscle is 3.8±0.7 mm, the superior oblique - 2.4±0.4 mm, the lateral rectus - 2.9±0.6 mm, the medial rectus - 4.1±0.5 mm, lower straight - 4.9 ± 0.8 mm.

A number of pathological conditions are accompanied thickening of the extraocular muscles

• Trauma-related causes include:
• contusional edema,
• intramuscular hematoma,
• orbital cellulite, as well as
• carotid-cavernous and
• dural-cavernous fistula.
• By the way -
• endocrine ophthalmopathy,
• pseudotumor of the orbit,
• lymphoma,
• amyloidosis,
• sarcoidosis,
• metastatic tumors, etc.

Superior ophthalmic vein on axial sections it has a diameter of 1.8±0.5 mm, on coronal sections - 2.7±1 mm. Enlargement of the superior ophthalmic vein detected on CT may indicate a number of pathological processes - obstructed outflow from the orbit (carotid-cavernous or dural-cavernous anastomosis), increased inflow (arteriovenous malformations of the orbit, vascular or metastatic tumors), varicose dilation of the superior ophthalmic vein and, finally, endocrine ophthalmopathy.

Blood in the paranasal sinuses has a density of 35-80 HU, depending on the duration of the hemorrhage. Inflammatory processes often lead to limited accumulation of fluid and look like a parietal or polyp-like thickening of the mucous membrane with a density of 10-25 HU. Frequent radiological symptoms of a fracture of the orbital walls bordering the paranasal sinuses are emphysema of the orbit and paraorbital tissues, as well as pneumocephalus.

8985 0

The eyeball is located in a bony container - the orbita. The eye socket has the shape of a truncated tetrahedral pyramid, the apex of which is turned towards the skull. The depth of the orbit in adults is 4-5 cm, the horizontal diameter at the entrance to the orbit (aditus orbitae) is about 4 cm, the vertical diameter is 3.5 cm.

The orbit has four walls (upper, lower, outer and inner), three of which (inner, upper and lower) border on the paranasal sinuses.

Bottom wall formed by the zygomatic bone, the orbital surface of the upper jaw and the orbital process of the palatine bone (Fig. 1). The lower wall covers the maxillary sinus, the inflammatory processes of which can quickly spread to the orbital tissue. The lower wall is most often exposed to blunt trauma (contusions); as a result, the eyeball may shift downward, limiting its upward and outward mobility when the inferior oblique muscle (m. obliquus inferior) is pinched.

Top wall formed by the frontal bone, in the thickness of which there is a sinus (sinus frontalis), and the small wing of the sphenoid bone. On the frontal bone from the side of the orbit, at the outer edge, there is a small bony protrusion (spina trochlearis), to which a tendon (cartilaginous) loop is fixed, through which the tendon of the superior oblique muscle (lig. m, obliqui superioris) passes. In the frontal bone at the top and outside there is a fossa for the lacrimal gland (fossa glandulae lacrimalis). The upper wall of the orbit is located on the border with the anterior cranial fossa, which is very important to consider in case of injuries.

Inner wall formed: from below - by the upper jaw and palatine bone; above - part of the frontal bone; behind - the sphenoid bone; in front - the lacrimal bone and the frontal process of the upper jaw.

There is a posterior lacrimal crest in the lacrimal bone, and an anterior lacrimal crest in the frontal process of the maxilla. Between them there is a depression - the fossa of the lacrimal sac (fossa sacci lacrimalis), in which the lacrimal sac (saccus lacrimalis) is located. Pit size 7x13 mm; below it passes into the nasolacrimal duct (ductus nasolacrimalis) 10-12 mm long, which passes through the wall of the maxillary bone and ends 2 cm posterior to the anterior edge of the inferior turbinate. When the wall is damaged, emphysema of the eyelids and orbits develops.

The inner, upper and lower walls of the orbit border on the paranasal sinuses, which often causes the spread of inflammation and the tumor process from them into the orbital cavity.

Outer wall- the most durable; it is formed by the zygomatic, frontal bones and the greater wing of the sphenoid bone.

In the walls of the orbit at its apex there are holes and slits through which large nerves and blood vessels 5-6 mm long pass into the orbital cavity (see Fig. 1).

Rice. 1. Structure of the orbit

Visual channel(canalis opticus) - a bone canal with a round hole with a diameter of 4 mm. Through it, the orbit communicates with the cranial cavity. The optic nerve (n. opticus) and the ophthalmic artery (a. ophthalmica) pass through the optic canal.

Superior orbital fissure(fissura orbitalis superior) is formed by the body of the sphenoid bone and its wings. Through it, the orbit connects to the middle cranial fossa. The gap is closed only by a thin connective tissue membrane, through which three branches of the optic nerve (n. ophthalmicus) pass - n. lacrimalis, n. nasoclliaris, n. frontalis, as well as the oculomotor nerve (n. oculomotorius); the superior ophthalmic vein (v. ophthalmica superior) emerges from the orbit through this gap. When the superior orbital fissure is damaged, the same complex of symptoms develops: complete ophthalmoplegia (lack of movement of the eyeball), ptosis (drooping of the upper eyelid), mydriasis (dilation of the pupil), tactile sensitivity disorder, dilation of the retinal veins, exophthalmos (protrusion of the eyeball).

Inferior orbital fissure(fissura orbitalis inferior) is formed by the lower edge of the large wing of the sphenoid bone and the body of the upper jaw. Through it, the orbit communicates with the pterygopalatine and temporal fossa. The gap is closed by a connective tissue membrane into which fibers of the orbital muscle (m. orbitalis) are woven, innervated by sympathetic nerve fibers. One of the two branches of the inferior ophthalmic vein (v. ophtalrmca interios) exits through this gap, and enters the orbit n. infraorbitalis and a. infraorbitalis, n. zygomaticus and rr. orbitalis from the pterygopalatine ganglion (gangl. pterygopalatinum).

Front and rear mesh openings(foramen ethmoidale anterius et posterius) - holes in the ethmoid plates. The nerves of the same name, arteries and veins (branches of the nasociliary nerve) pass through them.

Oval hole(foramen ovale) is located in the large wing of the sphenoid bone, connecting the middle cranial fossa with the infratemporal fossa. The mandibular nerve passes through it - n. n.andibularis (III branch of n. trigeminis).

On the inside, the orbit is covered with periosteum (periorbita), which is tightly fused with the bones that form it in the area of ​​the canalis opticus. Here is the tendon ring (annulus tendineus communis Zinni), in which all the extraocular muscles begin, except for the inferior oblique.

To the fascia of the orbit in addition to the periosteum include:

• vagina of the eyeball (vag. bulbi);
• muscular fascia (fasciae musculares);
• orbital septum (septum orbitale);
• fatty body of the orbit (corpus adiposum orbitae).

Vagina of the eyeball(vagina bulbi s. Tenoni) covers the entire eyeball, except for the cornea and the exit site of the n. opticus. Its thickest part (2.5-3.0 mm) is located in the equator of the eye, where the tendons of the extraocular muscles pass, which here acquire a dense connective tissue membrane. Dense cords also extend from the equatorial zone, connecting Tenon’s capsule with the periosteum of the walls and the edges of the orbit, thus creating a membrane that fixes the eyeball in the orbit. Below the eyeball is the suspensory ligament of Lockwood, which is of great importance in maintaining the eyeball in the correct position as it moves.

Episcleral (Tenon's) space(spatium episclerale) is represented by loose episcleral tissue (this circumstance is often used for instillation of drugs and implantation of transposition materials for therapeutic purposes).

The orbital septum (septum orbitae) is the fifth movable wall of the orbit, limiting the cavity of the orbit when the eyelids close. It is formed by fascia that connects the orbital edges of the cartilage of the eyelids with the bony edges of the orbit. The orbital cavity is filled with a fatty body; it is separated from the periosteum by a slit-like space. Vessels and nerves pass through the orbit from the apex to its base.

Blood supply

The ophthalmic artery (a. ophtalmica) enters the orbit through the optic foramen (foramen optidum) and immediately splits into several branches:

• central retinal artery (a. centralis retinae);
• supraorbital artery (a. supraorbitalis);
• lacrimal artery (a. lacrimalis);
• anterior and posterior ethmoidal arteries (aa. ethmoidalis anterior et posterior);
• frontal artery (a. frontalis);
• short and longer posterior ciliary arteries (aa. ciliares posteriores breves et longae);
• muscular arteries (aa. musculares).

17-09-2012, 16:51

Description

Eye socket shape

The eye socket contains

• eyeball,
• external muscles of the eye,
• nerves and blood vessels,
• fatty tissue, with
• useful gland

Rice. 2.1.1. View of the right and left eye sockets from the front (a) and from the side at an angle of 35 degrees (b) (according to Henderson, 1973): a - the camera is placed along the median axis of the skull. The right optic opening is slightly covered by the medial wall of the orbit. The left optic foramen is slightly visible as a small depression (small arrow). The large arrow points to the superior orbital fissure; b - the camera is placed at an angle of 35 degrees relative to the midline. The optic canal (small arrow) and the superior orbital fissure (large arrow) are clearly visible.

Rice. 2.1.2. Ocular and orbital axes and their relationship

Rice. 2.1.3. Bones that form the eye socket: 1 - orbital process of the zygomatic bone; 2 - zygomatic bone; 3 - frontosphenoid process of the zygomatic bone: 4 - orbital surface of the greater wing of the sphenoid bone; 5 - large wing of the sphenoid bone; 6 - lateral process of the frontal bone; 7 - fossa of the lacrimal gland; 8 - frontal bone; 9 - visual opening; 10 - supraorbital notch; 11 - trochlear fossa; 12 - ethmoid bone; 13 - nasal bone; 14 - frontal process of the upper jaw; 15 - lacrimal bone; 16 - upper jaw; 17 - infraorbital foramen; 18 - palatine bone; 19 - inferior orbital groove; 20 infraorbital fissure; 21-zygomaticofacial foramen; 22-superiorbital fissure

The medial walls of the orbit are almost parallel, and the distance between them is 25 mm. The outer walls of the orbit in adults are located relative to each other at an angle of 90°. Thus, the divergent axis of the orbit is equal to half 45°, i.e. 22.5° (Fig. 2.1.2).

Linear and volumetric dimensions of the orbit vary from person to person within fairly wide limits. However, the average values ​​are as follows. The widest part of the orbit is located at a distance of 1 cm from its anterior edge and is equal to 40 mm. The greatest height is approximately 35 mm, and the depth is 45 mm. Thus, in an adult, the volume of the orbit is approximately 30 cm3.

Forms the eye socket seven bones:

• ethmoid bone (os ethmoidale),
• frontal bone (os frontale),
• lacrimal bone (os lacrimale),
• maxillary bone (maxilla),
• palatine bone (os palatimim),
• sphenoid bone (os sphenoidale)
• and zygomatic bone (os zigomaticum).

Orbital edges

In an adult, the shape of the edge of the orbit (margoorbitalis) is a quadrilateral with a horizontal dimension of 40 mm and a vertical dimension of 32 mm (Fig. 2.1.3).

The largest part of the outer edge (margo lateralis) and the outer half of the lower edge (margo infraorbitalis) of the orbit is formed by cheekbone. The outer edge of the orbit is quite thick and can withstand heavy mechanical loads. When a bone fracture occurs in this area, it usually follows the line of the sutures. In this case, the fracture occurs either along the line of the zygomatic-maxillary suture in a downward direction or downward-outward along the line of the zygomatic-frontal suture. The direction of the fracture depends on the location of the traumatic force.

Frontal bone forms the upper edge of the orbit (margo siipraorbitalis), and its outer and inner parts participate in the formation of the outer and inner edges of the orbit, respectively. In newborns, the upper edge is sharp. It remains acute in women throughout life, and in men it rounds off with age. On the upper edge of the orbit on the medial side, the supraorbital recess (incisura frontalis) is visible, containing the supraorbital nerve (n. siipraorbitalis) and vessels. In front of the artery and nerve and slightly outward relative to the supraorbital notch there is a small supraorbital foramen (foramen supraorbitalis), through which the artery of the same name (arteria siipraorbitalis) penetrates into the frontal sinus and the spongy part of the bone.

Inner edge of the orbit(margo medialis orbitae) in the anterior sections is formed by the maxillary bone, which gives off a process to the frontal bone.

The configuration of the inner edge of the orbit is complicated by the presence in this area tear combs. For this reason, Whitnall suggests considering the shape of the inner edge as a wavy spiral (Fig. 2.1.3).

Lower edge of the orbit(margo inferior orbitae) is formed half by the maxillary and half by the zygomatic bones. The infraorbital nerve (n. infraorbitalis) and the artery of the same name pass through the lower edge of the orbit from the inside. They exit onto the surface of the skull through the infraorbital foramen (foramen infraorbitalis), located somewhat inward and below the lower edge of the orbit.

Bones, walls and openings of the orbit

As stated above, the orbit is formed by only seven bones, which also participate in the formation of the facial skull.

Medial walls eye sockets are parallel. They are separated from each other by the sinuses of the ethmoid and sphenoid bones. Lateral walls The orbit is separated from the middle cranial fossa in the back and from the temporal fossa in the front. The orbit is located directly under the anterior cranial fossa and above the maxillary sinus.

Superior wall of the orbit (Paries superior orbitae)(Fig. 2.1.4).

Rice. 2.1.4. Superior wall of the orbit (according to Reeh et, al., 1981): 1 - orbital wall of the frontal bone; 2- fossa of the lacrimal gland; 3 - anterior ethmoidal opening; 4 - large wing of the sphenoid bone; 5 - superior orbital fissure; 6 - lateral orbital tubercle; 7 - trochlear fossa; 8- posterior crest of the lacrimal bone; 9 - anterior crest of the lacrimal bone; 10 - sutura notra

The upper wall of the orbit is adjacent to the frontal sinus and the anterior cranial fossa. It is formed by the orbital part of the frontal bone, and posteriorly by the small wing of the sphenoid bone. The sphenofrontal suture (sutura sphenofrontalis) runs between these bones.

On the upper wall of the orbit there is a large number of formations that play the role of “tags”, used during surgical interventions. In the anterolateral part of the frontal bone there is a fossa of the lacrimal gland (fossa glandulae lacrimalis). The fossa contains not only the lacrimal gland, but also a small amount of fatty tissue, mainly in the posterior part (accessory fossa Pout of Dovigneau (Roch on-Duvigneaud)). From below, the fossa is limited by the zygomaticofrontal suture (s. frontozigomatica).

The surface of the bone in the area of ​​the lacrimal fossa is usually smooth, but sometimes roughness is detected at the site of attachment of the suspensory ligament of the lacrimal gland.

In the anteromedial part, approximately 5 mm from the edge, there are trochlear fossa and trochlear spine(fovea trochlearis et spina trochlearis), on the tendon ring of which the superior oblique muscle is attached.

Through the supraorbital notch, located on the upper edge of the frontal bone, passes supraorbital nerve, which is a branch of the frontal branch of the trigeminal nerve.

At the apex of the orbit, directly at the lesser wing of the sphenoid bone, there is optic hole- entrance to the optic canal (canalis opticus).

The upper wall of the orbit is thin and fragile. It thickens to 3 mm at the site where it is formed by the small wing of the sphenoid bone (ala minor os sphenoidale).

The greatest thinning of the wall is observed in cases where the frontal sinus is extremely developed. Sometimes, with age, resorption of the bone tissue of the upper wall occurs. In this case, the periorbita is in contact with the dura mater of the anterior cranial fossa.

Since the upper wall is thin, it is in this area Trauma causes a bone fracture with the formation of sharp bone fragments. Through the upper wall, various pathological processes (inflammation, tumors) developing in the frontal sinus spread into the orbit. It is also necessary to pay attention to the fact that the upper wall is located on the border with the anterior cranial fossa. This circumstance is of great practical importance, since injuries to the upper wall of the orbit are often combined with brain damage.

Inner wall of the orbit (Paries Мedialis orbitae)(Fig. 2.1.5).

Rice. 2.1.5. Inner wall of the orbit (after Reeh et al, 1981): 1 - anterior lacrimal ridge and frontal process of the maxilla; 2- lacrimal fossa; 3 - posterior lacrimal ridge; 4- lamina rarugasea of ​​the ethmoid bone; 5 - anterior ethmoidal opening; 6-optic foramen and canal, superior orbital fissure and spina recti lateralis; 7 - lateral angular process of the frontal bone: 8 - lower orbital margin with the zygomaticofacial foramen located on the right

The inner wall of the orbit is the thinnest (0.2-0.4 mm thick). It is formed by 4 bones:

• orbital plate of the ethmoid bone (lamina orbitalis os ethmoidale),
• frontal process of the maxilla (processus frontalis os zigomaticum),
• lacrimal bone
• and the lateral orbital surface of the sphenoid bone (fades orbitalis os sphenoidalis), located most deeply.

Visible in front of the inner wall tear trough(sulcus lacrimalis), continuing into the fossa of the lacrimal sac (fossa sacci lacrimalis). It contains the lacrimal sac. As it moves downwards, the lacrimal groove passes into the nasolacrimal canal (capalis nasolacrimalis).

The boundaries of the lacrimal fossa are outlined by two ridges - anterior and posterior lacrimal ridges(crista lacrimalis anterior et posterior). The anterior lacrimal ridge continues downwards and gradually passes into the lower edge of the orbit.

The anterior lacrimal ridge is easily palpable through the skin and is a mark during operations on the lacrimal sac.

As indicated above, the main part of the inner wall of the orbit is represented by the ethmoid bone. Since it is the thinnest of all the bone formations of the orbit, it is through it that the inflammatory process most often spreads from the sinuses of the ethmoid bone to the tissue of the orbit. This can lead to the development of cellulite, orbital phlegmon, thrombophlebitis of the orbital veins, toxic optic neuritis, etc. Children often experience acutely developing ptosis. The inner wall is also where tumors spread from the sinus to the orbit and vice versa. It is often destroyed during surgical interventions.

The inner wall is somewhat thicker only in the posterior sections, especially in the area of ​​the body of the sphenoid bone, as well as in the area of ​​the posterior lacrimal crest.

Ethmoid bone, participating in the formation of the internal wall, contains numerous air-containing bone formations, which can explain the rarer occurrence of fractures of the medial wall of the orbit than the thick floor of the orbit.

It is also necessary to mention that in the area of ​​the lattice seam there are often abnormalities in the development of bone walls, for example, congenital “gaping,” which significantly weakens the wall. In this case, the bone tissue defect is covered with fibrous tissue. Weakening of the inner wall also occurs with age. The reason for this is atrophy of the central areas of the bone plate.

In practical terms, especially when performing anesthesia, it is important to know the location of the anterior and posterior ethmoidal foramina, through which the branches of the ophthalmic artery pass, as well as the branches of the nasociliary nerve.

The anterior ethmoidal openings open at the anterior end of the frontoethmoidal suture, and the posterior ones - near the posterior end of the same suture (Fig. 2.1.5). Thus, the anterior openings lie at a distance of 20 mm behind the anterior lacrimal ridge, and the posterior ones at a distance of 35 mm.

Located deep in the orbit on the inner wall visual channel(canalis opticus), connecting the orbital cavity with the cranial cavity.

Outer wall of the orbit (Paries lateralis orbitae)(Fig. 2.1.6).

Rice. 2.1.6. Outer wall of the orbit (according to Reeh et al, 1981): 1 - frontal bone; 2 - large wing of the sphenoid bone; 3 - zygomatic bone; 4 - superior orbital fissure; 5 - spina recti lateralis; 6 - inferior orbital fissure; 7 - hole through which the branch passes from the zygomatic-orbital nerve to the lacrimal gland; 8 - zygomaticoorbital foramen

The outer wall of the orbit in its posterior section separates the contents of the orbit and middle cranial fossa. In front it borders with the temporal fossa (fossa temporalis), made by the temporal muscle (t. temporalis). It is delimited from the upper and lower walls by orbital fissures. These boundaries extend anteriorly to the sphenoid-frontal (sutura sphenofrontalis) and zygomatic-maxillary (sutura zigomaticomaxilare) sutures (Fig. 2.1.6).

Posterior part of the outer wall of the orbit forms only the orbital surface of the greater wing of the sphenoid bone, and the anterior section is the orbital surface of the zygomatic bone. Between them is the sphenoid-zygomatic suture (sutura sphenozigomatica). The presence of this suture greatly simplifies orbitotomy.

On the body of the sphenoid bone, at the junction of the wide and narrow parts of the superior orbital fissure, there is small bony prominence(spike) (spina recti lateralis), from which the external rectus muscle begins.

On the zygomatic bone near the edge of the orbit is located zygomaticoorbital foramen(i. zigomaticoorbitale), through which the branch of the zygomatic nerve (n. zigomatico-orbitalis) leaves the orbit, heading to the lacrimal nerve. In the same area, the orbital eminence (eminentia orbitalis; orbital tubercle of Withnell) is also found. The external ligament of the eyelid, the external “horn” of the levator, Lockwood’s ligament (lig. suspensorium), orbital septum (septum orbitale) and lacrimal fascia (/. lacrimalis) are attached to it.

The outer wall of the orbit is the place of easiest access to the contents of the orbit during various surgical interventions. The spread of the pathological process to the orbit on this side is extremely rare and is usually associated with diseases of the zygomatic bone.

When performing an orbitotomy, the ophthalmic surgeon must be aware that the posterior edge of the incision is distant from the middle cranial fossa at a distance of 12-13 mm in men and 7-8 mm in women.

Lower wall of the orbit (Paries inferior orbitae)(Fig. 2.1.7).

Rice. 2.1.7. Lower wall of the orbit (according to Reeh et al., 1981): 1 - lower orbital margin, maxillary part; 2 - infraorbital foramen; 3- orbital plate of the upper jaw; 4 - inferior orbital groove; 5 - orbital surface of the greater wing of the sphenoid bone; 6 - marginal process of the zygomatic bone; 7 - lacrimal fossa; 8 - inferior orbital fissure; 9 - origin of the inferior oblique muscle

The bottom of the orbit is also the roof of the maxillary sinus. This proximity is important from a practical point of view, since diseases of the maxillary sinus often affect the orbit and vice versa.

Inferior wall of the orbit formed by three bones:

• orbital surface of the upper jaw (fades orbitalis os maxilla), occupying most of the floor of the orbit,
• zygomatic bone (os zigomaticus)
• and the orbital process of the palatine bone (processus orbitalis os zigomaticus) (Fig. 2.1.7).

The shape of the lower wall of the orbit resembles an equilateral triangle.

Between the lower edge of the orbital surface of the sphenoid bone (fades orbitalis os sphenoidalis) and the posterior edge of the orbital surface of the maxillary bone (fades orbitalis os maxilla) there is inferior orbital fissure(fissura orbitalis inferior). A line that can be drawn through the axis of the inferior orbital fissure forms the outer border of the inferior wall. The internal border can be determined along the anterior and posterior ethmoid-maxillary sutures.

On the lateral edge of the lower surface of the maxillary bone begins infraorbital groove(groove) (sulcus infraorbitalis), which, as it moves forward, turns into a canal (canalis infraorbitalis). They contain the infraorbital nerve (p. infraorbitalis). In the embryo, the infraorbital nerve lies freely on the bony surface of the orbit, but gradually sinks into the rapidly growing maxillary bone.

The external opening of the infraorbital canal is located under the lower edge of the orbit at a distance of 6 mm (Fig. 2.1.3, 2.1.5). In children this distance is much less.

Inferior wall of the orbit has different densities. It is denser near and somewhat outside the infraorbital nerve. The inside wall becomes noticeably thinner. It is in these places that post-traumatic fractures are localized. The lower wall is also the site of spread of inflammatory and tumor processes.

Optic canal (Canalis opticus)(Fig. 2.1.3, 2.1.5, 2.1.8).

Rice. 2.1.8. Apex of the orbit (according to Zide, Jelks, 1985): 1 - inferior orbital fissure; 2- round hole; 3- superior orbital fissure; 4-optic foramen and optic canal

The optic foramen is located slightly inward of the superior orbital fissure, which is the beginning of the optic canal. The optic foramen is separated from the superior orbital fissure by the area connecting the lower wall of the lesser wing of the sphenoid bone, the body of the sphenoid bone with its lesser wing.

The opening of the optic canal facing the orbit has dimensions of 6-6.5 mm in the vertical plane and 4.5-5 mm in the horizontal plane (Fig. 2.1.3, 2.1.5, 2.1.8).

Visual channel leads to the middle cranial fossa(fossa cranialis media). Its length is 8-10 lilas. The axis of the optic canal is directed downward and outward. The deviation of this axis from the sagittal plane, as well as downward, relative to the horizontal plane, is 38°.

Through the canal pass the optic nerve (n. opticus), the ophthalmic artery (a. ophtalmica), immersed in the optic nerve sheath, as well as the trunks of the sympathetic nerves. After entering the orbit, the artery lies below the nerve, and then crosses the nerve and is located outside.

Since the position of the ophthalmic artery changes in the embryonic period, the canal takes the form of a horizontal oval in the posterior section and a vertical oval in the anterior section.

By the age of three, the visual canal reaches normal size. Its diameter of more than 7 mm must already be considered a deviation from the norm and the presence of a pathological process must be assumed. A significant increase in the optic canal is observed with the development of various pathological processes. In young children, it is necessary to compare the diameter of the optic canal on both sides, since it has not yet reached its final size. If a different diameter of the optic canals is detected (at least 1 mm), we can fairly confidently assume the presence of an anomaly in the development of the optic nerve or a pathological process localized in the canal. In this case, most often found optic nerve gliomas, aneurysms in the sphenoid bone area, intraorbital spread of tumors of the optic chiasm. It is quite difficult to diagnose intratubular meningiomas. Any long-term optic neuritis may indicate the possibility of developing intratubular meningioma.

A large number of other diseases leads to expansion of the optic canal. These are benign hyperplasia of the arachnoid membrane, fungal infections (mycoses), granulomatous inflammatory reaction (syphilitic gumma, tuberculoma). Dilation of the canal also occurs with sarcoidosis, neurofibroma, arachnoiditis, arachnoid cyst and chronic hydrocephalus.

Narrowing of the canal is possible with fibrous dysplasia or fibroma of the sphenoid bone.

Superior orbital fissure (Fissura orbitalis superior).

Shape and size of the superior orbital fissure vary significantly between individuals. It is located on the outside of the optic opening at the apex of the orbit and has the shape of a comma (Fig. 2.1.3, 2.1.6, 2.1.8, 2.1.9).

Rice. 2.1.9. Location of structures in the region of the superior orbital fissure and ring of Zinn (according to Zide, Jelks, 1985): 1 - external rectus muscle; 2-superior and inferior branches of the oculomotor nerve; 3- frontal nerve; 4- lacrimal nerve; 5 - trochlear nerve; 6 - superior rectus muscle; 7 - nasociliary nerve; 8 - levator of the upper eyelid; 9 - superior oblique muscle; 10 - abducens nerve; 11 - internal rectus muscle; 12 - inferior rectus muscle

It is limited by the small and large wings of the sphenoid bone. The upper part of the superior orbital fissure is narrower on the lateral side than on the medial side and below. At the junction of these two parts is the spine of the rectus muscle (spina recti).

Pass through the superior orbital fissure

• oculomotor,
• trochlear nerves,
• I branch of the trigeminal nerve,
• abducens nerve,
• superior orbital vein,
• recurrent lacrimal artery,
• sympathetic root of the ciliary ganglion (Fig. 2.1.9).

Common tendon ring(anulus tendineus communis; ring of Zinn) is located between the superior orbital fissure and the optic canal. Through the ring of Zinn, the optic nerve, ophthalmic artery, superior and inferior branches of the trigeminal nerve, nasociliary nerve, abducens nerve, sympathetic roots of the trigeminal ganglion enter the orbit and are thereby located in the muscular funnel (Fig. 2.1.8, 2.1.9).

Immediately below the ring in the superior orbital fissure passes superior branch of the inferior ophthalmic vein(v. ophthalmica inferior). Outside the ring on the lateral side of the superior orbital fissure there are trochlear nerve(n. trochlearis), superior ophthalmic vein (v. ophthalmica superior), as well as lacrimal and frontal nerves (nn. lacrimalis et frontalis).

Widening of the superior orbital fissure may indicate the development of various pathological processes, such as aneurysm, meningioma. Chordoma. pituitary adenoma, benign and malignant tumors of the orbit.

Sometimes an inflammatory process of unknown nature develops in the area of ​​the superior orbital fissure (Talasa-Hant syndrome, painful ophthalmoplegia). Inflammation may spread to the nerve trunks leading to the external muscles of the eye, which is the cause of the pain that occurs with this syndrome.

The inflammatory process in the area of ​​the superior orbital fissure can lead to violation of venous drainage of the orbit. The consequence of this is swelling of the eyelids and eye sockets. Tuberculous encephalic periostitis, spreading to structures located in the intraorbital fissure, has also been described.

Inferior orbital fissure (Fissura orbitalis inferior)(Fig. 2.1.7-2.1.10).

Rice. 2.1.10. Temporal, infratemporal and pterygopalatine fossa: 1 - temporal fossa; 2-pterygopalatine fossa; 3 - oval hole; 4 - pterygopalatine foramen; 5 - inferior orbital fissure; 6 - eye socket; 7 - zygomatic bone; 8 - alveolar process of the upper jaw

The inferior orbital fissure is located in the posterior third of the orbit between the bottom and the outer wall. Externally, it is limited by the greater wing of the sphenoid bone, and on the medial side by the palatine and maxillary bones.

The axis of the infraorbital fissure corresponds to the anterior projection of the optic foramen and lies at a level corresponding to the lower edge of the orbit.

The inferior orbital fissure extends forward more than the superior orbital fissure. It ends at a distance of 20 mm from the edge of the orbit. It is this point that is the landmark of the posterior border when performing subperiosteal removal of the bone of the lower wall of the orbit.

Directly below the inferior orbital fissure and on the outside of the orbit is located pterygopalatine fossa(fossa ptervgo-palatina), and in front - temporal fossa(fossa temporalis), performed by the temporal muscle (Fig. 2.1.10).

Blunt trauma to the temporal muscle can lead to hemorrhage into the orbit as a result of destruction of the vessels of the pterygopalatine fossa.

Behind the lower orbital fissure in the large wing of the main bone is located round hole(foramen rotundum), connecting the middle cranial fossa with the pterygopalatine fossa. Through this hole, branches of the trigeminal nerve, in particular the maxillary nerve (n. maxillaris), penetrate into the orbit. When leaving the foramen, the maxillary nerve gives off a branch - infraorbital nerve(n. infraorbitalis), which, together with the infraorbital artery (a. infraorbitalis), penetrates the orbit through the infraorbital fissure. Subsequently, the nerve and artery are located under the periosteum in the infraorbital groove (sulcus infraorbitalis), and then pass into the infraorbital canal (foramen infraorbitalis) and exit onto the facial surface of the maxillary bone at a distance of 4-12 mm below the middle of the edge of the orbit.

Through the inferior orbital fissure from the infratemporal fossa (fossa infratemporalis) the orbit also penetrates zygomatic nerve(n. zigomaticus), small branch of the pterygopalatine ganglion (gangsphenopalatina) and veins (inferior ophthalmic), draining blood from the orbit to the pterygoid plexus (plexus pterygoideus).

In the orbit, the zygomatic nerve divides into two branches- zygomatico-facial (zigomaticofacialis) and zygomaticotemporal (p. zigomaticotemporalis). Subsequently, these branches penetrate into the canals of the same name in the zygomatic bone on the outer wall of the orbit and branch in the skin of the zygomatic and temporal regions. A nerve trunk carrying secretory fibers separates from the zygomaticotemporal nerve towards the lacrimal gland.

The inferior orbital fissure is closed by Müller's smooth muscle. In lower vertebrates, contracting this muscle leads to protrusion of the eye.

Soft tissues of the orbit

Having outlined the basic information regarding the bone formations of the orbit, it is necessary to focus on its contents. The contents of the orbit are a complex set of anatomical formations that have different functional significance and belong to different tissues both in origin and structure (Fig. 2.1.11 - 2.1.13).

Rice. 2.1.11. Topographic relationship between the eyeball and the soft tissues of the orbit (no Ducasse, 1997): a - horizontal section of the orbit (1 - optic nerve: 2 - external rectus muscle: 3 - internal rectus muscle; 4 - ethmoid sinus; 5 - fibrous cords to the outer wall of the orbit); b - sagittal section of the orbit (1 - eyeball; 2 - superior rectus muscle; 3 - superior orbital vein; 4 - inferior rectus muscle; 5 - inferior oblique muscle; 6 - frontal sinus; 7 - maxillary sinus; 8 - cerebral hemisphere) ; c - coronal section of the orbit (1 - eyeball; 2 - levator of the upper eyelid; 3 - superior rectus muscle; 4 - external rectus muscle; 5 - superior oblique muscle; 6 - ophthalmic artery; 7 - internal rectus muscle; 8 - inferior oblique muscle muscle; 9 - inferior rectus muscle; 10 - frontal sinus; 11 - air cavities of the ethmoid bone; 12 - maxillary sinus

Rice. 2.1.12. Horizontal section passing at the level of the eyelid margin: the superficial head of the internal ligament of the eyelid is not visible at this level, but the orbital septum is visible. The posterior fibers of Horner's muscle arise from the pretarsal portion of the orbicularis oculi muscle, while the more anterior fibers of the muscle insert into the preseptal portion of the orbicularis oculi muscle. (1 - inferior rectus muscle; 2 - internal rectus muscle; 3 - external rectus muscle; 4 - retaining (“sentinel”) ligament of the internal rectus muscle; 5 - orbital septum; 6 - Horner’s muscle; 7 - lacrimal sac; 8 - lacrimal fascia; 9 - orbicularis oculi muscle; 10 - “cartilaginous” (tarsal) plate; 11 - fatty tissue; 12 - retaining (“sentinel”) ligament of the external rectus muscle)

Rice. 2.1.13. The ratio of the fascial sheaths and fatty tissue to the muscular infundibulum (according to Parks, 1975): 1 - inferior oblique muscle; 2 - intermuscular septum; 3 - fatty tissue located outside the muscle funnel; 4 - inferior rectus muscle; 5 - external rectus muscle; 6 - Zinn ring; 7 - levator of the upper eyelid; 8- superior rectus muscle; 9 - fatty tissue located above the muscle funnel; 10 Tenon capsule; 11 orbital septum; 12 conjunctiva; 13 orbital septum

Let's start the description with the tissue covering the bony walls of the orbit.

Periosteum (periorbita). The bones of the orbit, like all bones in the body, are covered by a layer of fibrous tissue called periosteum. It must be emphasized that the periosteum is not tightly fixed to the bone almost throughout its entire length. It is tightly attached only to the edges of the orbit, in the area of ​​the superior and inferior orbital fissures, as well as at the optic canal, lacrimal gland and lacrimal crests. In other places it comes off easily. This can occur both during surgery and in the post-traumatic period as a result of accumulation of exudate or transudate under the periosteum.

At the optic opening, the periosteum gives off fibrous cords to the external muscles of the eye, as well as deep into the orbit, dividing the fatty tissue into lobules. It also envelops blood vessels and nerves.

In the optic canal, the periosteum unites with the endosteal layer of the dura mater.

The periosteum also covers the superior orbital fissure, with the exception of the passage of blood vessels and nerves.

In front, the periosteum covers the frontal, zygomatic and nasal bones. Through the inferior orbital fissure it spreads towards the pterygoid and palatine bones and the temporal fossa.

The periosteum also lines the lacrimal fossa, forming the so-called lacrimal fascia, which envelops the lacrimal sac. In this case, it spreads between the anterior and posterior lacrimal ridges.

The periosteum of the orbit is intensively supplied with blood vessels that exclusively anastomose with each other, and is innervated by branches of the trigeminal nerve.

The periosteum, being a dense fibrous tissue, serves as a rather powerful obstacle to the spread of blood after injury, inflammatory process, tumors emanating from the paranasal sinuses. However, it eventually collapses.

For Coffey's disease(infantile cortical hyperostosis) for an unknown reason, inflammation of the periosteum develops, leading to proptosis and increased intraorbital pressure to such an extent that glaucoma develops. Granular cell sarcoma also arises from the periosteum. The periosteum may be the only barrier between the contents of the orbit and the dermoid cyst, mucocele.

The potential space between the periorbita and the bones allows for fairly complete removal of orbital tissue for tumors. It is also necessary to point out that the periosteum must be preserved as much as possible when removing tumors, since it is an obstacle to its further spread.

Fascia. The organization of the fibrous tissue of the orbit has traditionally been discussed using anatomical terms. Based on this, the fascia of the orbit is divided into three parts: the fascial membrane covering the eyeball (Tenon’s capsule; fascia bitlbi), the membranes. covering the external muscles of the eye and “sentinel” ligaments, originating from the fascia of the external muscles of the eye and heading to the bones and eyelids (Fig. 2.1.12).

Thanks to the work of Koomneef, who used methods of reconstructive anatomy (reconstruction of the volumetric arrangement of structures based on the analysis of serial sections), the soft tissues of the orbit are currently considered as a complex biomechanical system that ensures the mobility of the eyeball.

Vagina of the eyeball(Tenon's capsule; fascia bulbi) (Fig. 2.1.13, 2.1.14)

Rice. 2.1.14. Posterior part of Tenon's capsule: The picture shows part of Tenon's capsule of the right orbit after removal of the eyeball (1 - conjunctiva; 2 - external rectus muscle; 3 - superior rectus muscle; 4 - optic nerve; 5 - superior oblique muscle; 6 - mouth of the meibomian glands; 7 - lacrimal punctum; 8 internal rectus muscle, 9 - lacrimal caruncle; 10 - Tenon's capsule; 11 - inferior oblique muscle; 12 - inferior rectus muscle)

is a connective tissue membrane that starts in the posterior part of the eye at the entrance of the optic nerve and moves anteriorly, enveloping the eyeball. Its anterior edge fuses with the conjunctiva of the eye in the corneoscleral region.

Although Tenon's capsule is tightly attached to the eye, it can still be separated from it at a certain distance. In this case, bridges of delicate fibrous tissue remain between the eyeball and the capsule. The resulting space is called potential Tenon space.

After enucleation of the eyeball, the implants are placed into the cavity of Tenon’s capsule or slightly back, within the muscular funnel.

Tenon's capsule is susceptible to various inflammatory processes. This occurs with orbital pseudotumors, scleritis and choroiditis. The inflammatory process often ends with fibrosis of the capsule.

Outside Tenon's capsule connects to the system of fibrous cords and layers, dividing the fatty tissue of the orbit into lobules (Fig. 2.3.12). The eye is thus tightly connected to the surrounding fatty tissue, but at the same time retains the ability to rotate in different planes. This is also facilitated by the presence of elastic fibers in the connective tissue surrounding Tenon’s capsule.

Four muscles penetrate through Tenon's capsule (Fig. 2.3.14). This occurs approximately 10 mm from the limbus. When passing through Tenon's capsule, fibrous layers (intermuscular septa) depart into the muscle. The eyeball is covered with Tenon's capsule just behind the insertion of the rectus muscles. Thus, in front of the site of attachment of the muscles to the eyeball, three tissue layers are found: the most superficial - the conjunctiva, then Tenon's capsule and the most internal - the intramuscular septum (septa). It is important for the ophthalmologist to remember these formations, especially during muscle surgery. In cases of dissection of Tenon's capsule at a distance of more than 10 mm from the limbus, the fatty tissue of the orbit protrudes forward, leading to orbital prolapse.

Tenon's capsule forms a series of facial formations. In the horizontal plane, the capsule extends from the internal rectus muscle to its attachment to the periosteum of the zygomatic bone, and from the external rectus muscle to the lacrimal bone.

Between the superior rectus muscle and the levator aponeurosis of the upper eyelid there is also many fascial bands, which coordinate the movement of the eye and eyelid. If these connective tissue cords are removed, which happens when a levator resection is performed for ptosis, hypotropia (downward squint) may develop.

The fascial membranes of the external muscles of the eye are thin, especially in the posterior areas. Anteriorly they thicken significantly.

As stated above, fibrous cords extend from the external muscles of the eye towards the walls of the orbit. As they move away from the muscles, they are more and more clearly identified as anatomical formations. These fibrous cords are called suspensory ligaments. The most powerful ligaments are those that originate from the rectus muscles (internal and external) (Fig. 2.1.12, 2.1.15).

Rice. 2.1.15. Distribution of the fascial membranes of the right orbit (posterior view): 1 - upper part of the levator fascia of the upper eyelid (central part of the superior transverse ligament); 2 - common part of the fascia of the levator of the upper eyelid and the superior rectus muscle; 3-medial ligament of the lacrimal gland; 4 superior transverse ligament (together with 1 and 2); 5 - intermuscular membranes; 6 - lacrimal gland; 7 - lower transverse ligament; 8 - posterior lacrimal ridge, 9 - medial capsular ligament (“sentinel” ligament); 10 - lateral tubercle of the orbit (Withnell ligament); 11-lateral capsular (“sentinel”) ligament; 12 - Tenon’s capsule (posterior); 13 - superior oblique muscle tendon and block

External suspensory ligament more powerful. It begins on the posterior surface of the lateral orbital eminence (Withnell's tubercle) and is directed towards the external fornix of the conjunctiva and the outer part of the orbital septum (Fig. 2.1.15).

Internal suspensory ligament a originates slightly behind the posterior lacrimal ridge and goes to the lateral part of the orbital septum, the lacrimal caruncle and the semilunar fold of the conjunctiva.

Upper transverse Withnell's ligament many authors consider it as the superior suspensory ligament.

Lockwood once described hammock-like structure, spreading under the eyeball from the inner wall of the orbit to the outer wall. It is formed by fusion of the fascia of the inferior rectus and inferior oblique muscles. This ligament can support the eye even after the maxilla and floor of the orbit are removed. It is more powerful in front of the inferior oblique muscle.

In the fascial membrane of all the external muscles of the eye one can find varying amounts smooth muscle fibers. Most of them are in the fascia of the superior and inferior rectus muscles.

The dense connective tissue surrounding the extrinsic muscles of the eye forms a funnel, the apex of which is located in the ring of zinn. The anterior border of the muscular funnel lies at a distance of 1 mm from the place of attachment of the external muscles of the eye to the sclera.

All strands of fibrous tissue of the orbit, including fibrous layers of adipose tissue lobules, belong to the fascicular system of the orbit. This dense connective tissue can be subject to pathological lesions such as nodular fasciitis, inflammatory pseudotumor.

More information about the fascial formations of the orbit can be found in the section on the description of the extrinsic muscles of the eye.

Fatty tissue of the orbit. All spaces of the orbit that do not contain the eyeball, fascia, nerves, vessels or glandular structures are filled with fatty tissue (Fig. 2.1.11). Fatty tissue acts as a shock absorber for the eyeball and other structures of the orbit.

In the anterior part of the orbit, the fatty tissue is dominated by fibrous connective tissue, while in the posterior parts there are fatty lobules.

The fatty tissue of the orbit is divided by a connective tissue septum into two parts - central and peripheral. Central part lies in the muscular funnel. In its anterior part, it is limited by the posterior surface of the eye, covered with Tenon's capsule. Peripheral part of the fatty tissue of the orbit is limited by the periosteum of the orbital walls and the orbital septum.

When the orbital septum is opened in the area of ​​the upper eyelid, a preaponeurotic fat pad. Inside and below the block is the internal fat pad of the upper eyelid. It is lighter and denser. In the same area there is the subtrochlear nerve (n. intratrochlearis) and the terminal branch of the ophthalmic artery.

The main cellular component of fat lobules is lipocyte, the cytoplasm of which is made of neutral free and bound fats. Clusters of lipocytes are surrounded by connective tissue containing numerous blood vessels.

Despite the presence of a large amount of fatty tissue, tumors in the orbit, the source of which can be adipose tissue, are extremely rare (lipoma, liposarcoma). It is assumed that liposarcoma of the orbit generally develops not from lipocytes, but from ectomesenchymal cells.

Most often, adipose tissue is involved in the development inflammatory pseudotumors of the orbit, being its structural component. As the disease progresses, lipocytes are destroyed, releasing free lipids. Free, extracellularly located lipids, in turn, enhance the inflammatory process, causing a granulomatous reaction. This inflammatory process is completed by fibrosis of the affected and surrounding tissues. This condition is assessed as lipogranuloma. Trauma to the orbit, accompanied by necrosis of fatty tissue, can lead to the development of lipogranuloma.

Almost all pathological processes of a granulomatous nature (mycoses, Wegener's granulomatosis, etc.) involve adipose tissue.

Article from the book: .