The structure of the human eye socket and the purpose of its individual parts. Superior and inferior orbital fissures
60. What anatomical structures pass through the superior orbital fissure?
All the oculomotor nerves (oculomotor, blocky, abducens), 1 branch of the trigeminal nerve (optic nerve), the superior orbital vein pass through the superior orbital fissure.
61. List the main clinical signs of the superior orbital fissure syndrome.
With damage to the bones of the orbit, the so-called "Superior orbital fissure syndrome". In this case, there will be symptoms of damage to the nerves and blood vessels passing through the superior orbital fissure (see above): 1. Complete paralysis of all muscles of the eyeball (complete ophthalmoplegia) 2. Ptosis of the upper eyelid (ptosis) 3. Mydriasis - dilated pupil 4. Disorder sensitivity of the skin of the eyelids, conjunctiva and cornea (damage to 1 pair of trigeminal nerve) 5. Mild exophthalmos (retrobulbar hematoma due to damage to the superior orbital vein)
Section II. Refraction.
62. Indicate visual acuity if the subject sees line 10 of the Sivtsev table from a distance of 3.5 m.
According to the Snellen formula, V \u003d d / D. V is visual acuity d is the distance from which the patient sees line 10 (3.5 m) D is the distance from which the patient should see line 10 (5 m) Thus, V \u003d 3.5 /five = 0.7 Consequently, the subject's visual acuity is 0.7
63. A 70-year-old patient has a visual acuity of 1.0. Is it possible to judge the type of clinical refraction on the basis of these data? If so, what kind of refraction are we talking about?
Yes, you can. If the patient's visual acuity is 1.0, this means that his refraction is emmetropia or hyperopia (due to the tension of accommodation at a young age with hyperopia, visual acuity may be normal). However, in this case (a 70-year-old patient), the volume of accommodation is zero, hence the only possible option is emmetropia.
64. Are glasses for nearness necessary for a person at the age of 55 with 2.5 d hyperopia in both eyes? If so, write a prescription.
Yes, we do.
Rp .: Reading glasses.
Ou Sph + 5.0 Diopters
65. Is there a surgical treatment for progressive myopia? If so, what is the operation?
Yes, it does. With progressive myopia, an operation is performed aimed at strengthening the posterior segment of the eye. Strips of canned autofascia or homosclera are passed along the posterior pole of the sclera and sutured 5-6 mm from the limbus. After engraftment of grafts, the sclera in the posterior pole thickens, which prevents its further stretching.
66. In the study of clinical refraction in the vertical meridian revealed hyperopia 1.0 D, and in the horizontal - hypermegropia 2.5 D. Write a detailed diagnosis of this condition. H 1.0 D
Complex hyperopic astigmatism
H 2.5D direct type (vertical refraction
the meridian is stronger).
67. What is the patient's visual acuity if he distinguishes the details of the signs of the first row of Sivtsev's table from a distance of 1.5 m?
V \u003d d / D \u003d 1.5 / 50 \u003d 0.03
68. Write out near glasses for a 70-year-old patient who has 2.0 D hyperopia in both eyes.
Rp .: Reading glasses.
Ou Sph + 5.0 Diopters
69. O what factors does the volume of accommodation depend on?
The main factor that determines the amount of accommodation is age the patient. With age, physiological involutional processes occur in the lens, which are expressed in the densification of its tissue, which leads to a gradual decrease in the volume of accommodation.
Increase in myopia by 1.0 Diopters and more throughout the year.
71. Give a definition of the concept of "astigmatism".
Astigmatism - combination in one eye of different types of refraction or different degrees of one type of refraction.
72. If the subject has a visual acuity of 0.01, then from what maximum distance can he count the fingers of your hand?
V \u003d d / D, therefore d \u003d V x D V = 0.01 D \u003d 50 m (since the thickness of the fingers roughly corresponds to the thickness of the characters in the first line of the Sivtsev table) Thus, d \u003d V x D \u003d 0.01 x 50 m \u003d 0.5 m. The subject will be able to count his fingers from a distance of 50 cm.
73. How old is a patient who, having a hyperopia of 1.0 D, uses spherical glasses of +2.0 D for near?
In this case, +1.0 D spherical glasses are required to correct hyperopia. An additional +1.0 D is needed to correct presbyopia. Thus, the volume of accommodation in this patient is reduced by 1.0 D, which corresponds to the approximate age of 40 years.
74. Is there a relationship between age and the position of the further point of view?
No. The position of the further point of clear vision depends only on the type of clinical refraction.
75. Indicate the type of the most acceptable correction of high degree anisometropia.
Contact correction.
76. What can be the cause of incorrect astigmatism?
Irregular astigmatism is characterized by local changes in refractive power in different segments of the same meridian. The causes of incorrect astigmatism are most often corneal diseases: trauma, scars, keratoconus, etc.
77. Are near glasses necessary for a patient at the age of 50 who has myopia 2.0 D in both eyes? If so, write a prescription.
No, they are not needed. For the correction of myopia, glasses of -2.0 D are required, and for the correction of presbyopia at this age - glasses of +2.0 D. Therefore, glasses are not needed.
78. List the indications for the appointment of bifocal glasses.
Moderate and high myopia and hyperopia in the elderly.
79. What medicines can impair near vision. Why?
Deterioration of near vision is associated with accommodation paralysis. Accommodation paralysis can be caused by atropine-like drugs (anticholinergics).
80. On the figure of the cross, give an example of mixed astigmatism.
With mixed astigmatism in one meridian there is myopia, in the other hyperopia:
M 1.0 D H 2.0 D
81. A spherical positive lens has a main focal length of 50 cm. What is its optical power?
D \u003d 1 / F \u003d 1 / 0.5 = 2.0 D
82. Can a person at the age of 25 with hyperopia at 2.5 D have visual acuity equal to 1? If so, by what factors?
Yes maybe. Due to the tension of accommodation (an increase in the curvature of the lens) with a weak degree of hyperopia at a young age, the rays can be focused on the retina and the distance vision does not suffer.
83. Write a prescription for near glasses for a 60-year-old patient who has 1.0D myopia in both eyes?
Rp .: Close up glasses
Ou Sph + 2.0 Diopters
84. If it becomes necessary to correct anisometropia with spherical glasses, what is the basic principle that should be followed?
Basic principle: the difference in refractive power between spherical glasses for different eyes should not exceed 2.0 D.
85. What is the main difference between a spherical stack and a cylindrical one?
Spherical glass refracts rays of light equally in all meridians (directions), while cylindrical glass refracts rays only in a plane perpendicular to the axis of the cylinder. Due to this feature, cylindrical glasses are used in the correction of astigmatism.
86. What is the refractive power of the cornea?
87. Can a person at the age of 65 with a hyperopia of 2.5 D have a visual acuity of 1? Why?
No, it cannot, since the volume of accommodation after 60 years is zero (that is, there is practically no accommodation). Therefore, the eye cannot, by increasing the curvature of the lens, focus the light beams on the retina, and they are focused behind the retina (since the patient has hyperopia).
88. A 72-year-old patient has a myopia of 2.0 D in both eyes. The optical media are transparent, the fundus is normal. Write a prescription for glasses.
Rp .: Glasses for distance Rp .: Close up glasses
Ou Sph -2.0 Diopters Ou Sph +1.0 Diopters
Dр \u003d 64 mm Dр \u003d 62 mm
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The orbit (orbita) is a paired bone cavity in the front 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, moreover, loses one facet in the region of 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 - at right angles to each other. If we take the optic nerves as reference points, then the angle of divergence of the optic axes normally does not exceed 45º, and that of the optic nerve and the optic axis - 22.5º, which is clearly seen on axial computed tomograms.
The angle of divergence of the visual axes determines the distance between the orbits - 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 ranges from 18.5 mm to 30.7 mm, ideally 25 mm. Both decreased (stenopia) and increased (euryopia) interorbital distance indicate the presence of serious craniofacial pathology.
The length of the anteroposterior axis (“depth”) of the orbits in an adult is 45 mm on average. Therefore, all manipulations in the orbit (retrobulbar injections, subperiosteal separation of tissues, the size of implants introduced to replace bone defects) should be limited to 35 millimeters from the bone 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 variants of which are "deep narrow" and "shallow wide" orbits.
The volume of the cavity of the orbit (cavitas orbitalis) is somewhat less than is commonly believed, and is 23–26 cm 3, of which only 6.5–7 cm 3 falls on the eyeball. In women, the orbital volume is 10% less than in men. Ethnicity has a great influence on the parameters of the orbit.
The edges of the entrance to the eye socket
The edges (supraorbital - margo supraorbitalis, infraorbital - margo infraorbitalis, lateral - margo lateralis, medial - margo medialis) of the orbit make up 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", extinguishing deformations of the facial skeleton during chewing, as well as in craniofacial injuries. In addition, the profile of the orbital rim 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 displaced posteriorly compared to the medial edge, and the lower edge compared to the upper one, forming a spiral with right angles. This provides a wide field of view and bottom-out gaze, but leaves the anterior half of the eyeball unprotected from the action of a wounding agent moving on the same side. The spiral of the entrance to the orbit is open in the region of the medial edge, where it forms the fossa of the lacrimal sac, fossa sacci lacrimalis.
The continuity of the supraorbital edge on the border between the middle and its inner third is violated by the supraorbital notch (incisura supraorbitalis), through which the artery, vein and nerve of the same name (a., V. Et n. Supraorbitalis) are thrown from the orbit to the forehead and into the sinus. The shape of the cut is very variable, its width is approximately 4.6 mm, its height is 1.8 mm.
In 25% of cases (and in the female population - up to 40%), instead of a bone notch, there is an opening (foramen supraorbitale) or a small bony canal through which the specified neurovascular bundle passes. The hole dimensions are usually smaller than the cutouts and are 3.0 x 0.6 mm.
- Infraorbital margin (margo infraorbitalis) , formed by the upper jaw and the zygomatic bone, has less strength, therefore, with blunt trauma, the orbit undergoes a transient wave-like deformation, transmitted to the lower wall and causing an isolated ("explosive") fracture thereof with displacement of the lower muscle complex and adipose 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 upper jaw.
- The most durable are lateral and supraorbital edges (margo lateralis et supraorbitalis)
formed by the thickened edges of the zygomatic and frontal bones. As for the supraorbital margin, it is important
an additional factor of its mechanical strength is a well-developed frontal sinus, which dampens the impact on this area.
Orbital walls
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Orbital walls |
The structures that form them |
Bordering formations |
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Medial |
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Lateral |
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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 part) over 1.5 cm - by the lesser wing of the sphenoid bone;
Similarly 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 is a wedge-frontal suture, sutura sphenofrontalis.
At the root of each lesser wing is the optic canal, canalis opticus, through which the optic nerve and ocular artery pass.
On the side, at the base of the zygomatic process of the frontal bone, directly behind the supraorbital edge, there is a small depression - the fossa of the lacrimal gland (fossa glandulae lacrimalis), where the gland of the same name is located.
Medially, 4 mm from the supraorbital margin, there is a block fossa (fossa trochlearis), next to which there is often a block 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 upper oblique muscle of the eye, which sharply changes its direction here, passes.
Damage to the block during trauma 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 orbital wall (paries medialis) is formed (in the antero-posterior direction) by the frontal process of the upper jaw, lacrimal and ethmoid bones, as well as a small wing of the sphenoid bone. Its upper border is the frontal-ethmoid suture, the lower one is the ethmoid-maxillary suture. Unlike other walls, it is rectangular in shape.
The basis of the medial wall is the orbital (which stubbornly continues to be called "paper") plate of the ethmoid bone 3.5-5.0 × 1.5-2.5 cm in size 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; therefore, the maximum width of the orbit is noted not in the plane of entry into it, but 1.5 cm deeper. As a result, 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 cells, divided by septa (septa) into the anterior and posterior parts. Large and numerous small partitions between the ethmoid cells (cellulae ethmoidales) strengthen the medial wall from the side of the nose, performing the function of buttresses. Therefore, the medial wall turns out to be stronger than the lower one, especially with a branched system of lattice septa and a relatively small size of the orbital plate.
In 50% of the eye sockets, the ethmoid labyrinth reaches the posterior lacrimal crest, and in another 40% of cases, the frontal process of the upper jaw. This anatomical variant is called "presentation of the trellised maze".
At the level of the frontal-ethmoid suture, 24 and 36 mm behind the anterior lacrimal crest, in the medial wall of the orbit there are anterior and posterior lattice openings (foramina ethmoidalia anterior et posterior), leading to the channels of the same name, which serve to pass from the orbit into the ethmoid cells and cavity the nose of the branches of the same name of the ophthalmic artery and the nasal ciliary nerve. It should be emphasized that the posterior ethmoid 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 ethmoid foramen , 12 - the distance from the anterior lattice opening to the posterior, and, finally, 6 - the distance from the posterior lattice opening to the optic canal). Exposure of the posterior lattice foramen during the subperiosteal separation of the orbital tissues 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 located mostly in front of the tarso-orbital fascia, the fossa of the lacrimal sac, 13 × 7 mm in size, formed by the anterior lacrimal ridge of the frontal process of the upper jaw and the lacrimal bone with its posterior lacrimal ridge.
The lower part of the fossa smoothly passes into the bony 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, ethmoid labyrinth and sphenoid sinus. This circumstance is of great clinical importance, since these cavities are often a source of acute or chronic inflammation, which spreads 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 lattice) openings in it. In addition, in the lacrimal bone and the orbital plate of the ethmoid bone, congenital dehiscences are often found, 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 strongest, it is formed in its front half by the zygomatic bone, and in the back - by the orbital surface of the large 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.
In front, the boundaries of the lateral wall are the fronto-zygomatic (sutura frontozygomatica) and zygomatic-maxillary (sutura zygomaticomaxillaris) sutures, behind - the upper and lower orbital fissures.
The central third - trigone (triangle or wedge-scaly seam, 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, keeping in mind 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 pterygo-palatine fossa, and in the region of the apex from the middle cranial fossa.
Bottom wall
The lower wall of the orbit
which is the "roof" of the maxillary sinus, formed mainly by the orbital surface of the body of the upper jaw, in the antero-outer region - by the zygomatic bone, in the posterior region - by a small orbital process of the perpendicular plate of the palatine bone. The area of \u200b\u200bthe 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 participate.
The lower wall of the orbit has the shape of an equilateral triangle. It is the shortest (about 20 mm) wall that does not reach the apex of the orbit, but ends with the inferior orbital fissure and the pterygo-palatine fossa. The line running along the inferior orbital fissure forms the outer border of the orbital fundus. The inner border is defined as a continuation anteriorly and posteriorly of the ethmo-maxillary suture.
The thinnest part of the bottom of the orbit is the infraorbital groove, which crosses it approximately in half, passing anteriorly into the canal of the same name. The rear part of the inner half of the lower wall is slightly stronger. The rest of its sections are very resistant to mechanical stress. The thickest point is the junction of the medial and inferior walls of the orbit, 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 orbital bottom defects. Giving the reconstructed wall a flat profile will lead to an increase in the orbital volume and the preservation of enophthalmos in the postoperative period.
Fifteen-degree elevation of the inferior orbital wall towards the apex of the orbit and its complex profile prevent the surgeon from inadvertently guiding the raspator into the deep parts of the orbit and make direct damage to the optic nerve during orbital fundus reconstruction unlikely.
In case of injuries, fractures of the lower wall are possible, which are sometimes accompanied by the lowering of the eyeball and limitation of its mobility upward and outward when the lower oblique muscle is pinched.
Three of the four walls of the orbit (except for the outer one) are bordered by 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.
Orbital seams
The orbital surface of the large wing of the sphenoid bone (facies orbitalis alae majoris ossis sphenoidalis) is not uniform in thickness. The anterolateral third, which connects to the orbital surface of the zygomatic bone through the wedge-zygomatic suture (sutura sphenozygomatica), and the posteromedial third, which forms the inferior border of the superior orbital fissure, are relatively thin. Therefore, the zone of the wedge-zygomatic suture is convenient for external orbitotomy.
Near wedge-frontal sutura (sutura sphenofrontalis) in the large wing of the sphenoid bone at the anterior edge of the superior orbital fissure there is a non-permanent hole of the same name containing a branch of the lacrimal artery - a recurrent meningeal artery (anastomosis between a.meningea media from the pool of the external carotid artery and the ophthalmic artery from the pool of the internal carotid artery).
Wedge-zygomatic The suture, due to its length and three-dimensional structure, plays an extremely important role in the process of reduction of the zygomatic bone in zygomatic-orbital fractures.
Frontal zygomatic suture (sutura frontozygomatica) provides rigid fixation of the zygomatic bone to the frontal.
Frontal lattice suture is considered an important identification point marking the upper boundary of the trellis maze. Accordingly, osteotomy above the frontal-ethmoidal suture is fraught with damage to the dura mater of the brain (TDM) in the area of \u200b\u200bthe frontal lobe.
Zygomatic-facial (canalis zygomaticofacialis) and zygomatic (canalis zygomaticotemporalis) canals contain the 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 a surgeon who separates the temporal muscle during an external orbitotomy.
11 mm below the frontal-zygomatic suture and 4-5 mm behind the orbital margin, the outer orbital tubercle (tuberculum orbitale Whitnall) - a slight elevation of the orbital edge of the zygomatic bone, found in 95% of people. Attached to this important anatomical point are:
- fixing ligament of the lateral rectus muscle (tendon extension, lacertus musculi recti lateralis, sentinel ligament in the terminology of V.V. Vita);
- lower eyelid suspension ligament (Lockwood lower transverse ligament, Lockwood);
- lateral ligament of the eyelids;
- the lateral horn of the aponeurosis of the muscle lifting the upper eyelid;
- orbital septum (tarso-orbital fascia);
- fascia of the lacrimal gland.
Communication with cranial cavities
The outer, the 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 large 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 pterygo-palatine and infratemporal fossa. Through it, one of the two branches of the inferior orbital vein leaves the orbit (the second flows into the superior orbital vein), anastomosed with the pterygoid venous plexus, and also the inferior orbital nerve and artery, the zygomatic nerve and the orbital branches of the pterygopalatine node enter.
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, continuing into the fossa of the lacrimal sac, fossa sacci lacrimalis. The latter goes down into the nasolacrimal canal, canalis nasolacrimalis.
There are two holes along the upper edge of the medial wall of the orbit: the anterior ethmoid foramen, foramen ethmoidale anterius, at the anterior end of the frontal-ethmoid suture, and the posterior ethmoid foramen, 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 a thin periosteum.
Through the superior orbital fissure, leading to the middle cranial fossa, the oculomotor ( n. oculomotorius), diverting ( n. abducens) and blocky ( n. trochlearis) nerves, as well as the first branch of the trigeminal nerve ( r. ophthalmicus n. trigemini). The superior orbital vein, which is the main venous collector of the orbit, also passes here.
The longitudinal axes of both eye sockets, drawn from the middle of the entrance to them to the middle of the optic canal, converge in the area of \u200b\u200bthe Turkish saddle.
Eye socket holes and slots:
- Bone canal optic nerve ( canalis opticus) with a length of 5-6 mm. It begins in the eye socket with a round hole ( foramen optician) with a diameter of about 4 mm, connects its cavity with the middle cranial fossa. Through this canal, the optic nerve enters the eye socket ( n. opticus) and the ocular artery ( a. ophthalmica).
- 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. Tightened by a firebox connective tissue film through which three main branches of the optic nerve pass into the orbit ( n. ophthalmicus) - lacrimal, nasal and frontal nerves ( nn. laеrimalis, nasociliaris et frontalis), as well as the trunks of the block, abducens and oculomotor nerves ( nn. trochlearis, abducens and oculomolorius). Through the same slit, the upper ocular vein leaves it ( n. ophthalmica superior). When this area is damaged, a characteristic symptom complex develops - "superior orbital fissure syndrome", but it may not be fully expressed when not all are damaged, but only individual nerve trunks passing through this gap.
- Inferior orbital fissure (fissuga orbitalis inferior). Formed by the lower edge of the greater wing of the sphenoid bone and the body of the upper jaw, it provides communication of the orbit with the pterygopalatine (in the posterior half) and temporal fossa. This gap is also closed by a connective tissue membrane, into which fibers of the orbital muscle ( m. orbitalis), innervated by the sympathetic nerve. Through it, one of the two branches of the lower ocular vein leaves the orbit (the other flows into the superior ocular vein), which then anastomoses with the wing with a visible 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 node ( ganglion pterygopalatinum).
- 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), from which the infraorbital nerve departs in the pterygopalatine fossa ( n. infraorbitalis), and in the inferior temporal - the zygomatic nerve ( n. zygomaticus). Both nerves then enter the orbital cavity (the first subperiosteal) through the inferior orbital fissure.
- Lattice holes on the medial wall of the orbit ( foramen ethmoidale anterius et posterius), through which the nerves of the same name (branches of the nasal ciliary nerve), arteries and veins pass.
- Oval hole is located in the large wing of the sphenoid bone, connecting the middle cranial fossa with the infratemporal. The third branch of the trigeminal nerve ( n. mandibularis), but it does not take part in the innervation of the organ of vision.
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Anatomical education |
Topographic and anatomical characteristics |
Content |
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Supraorbital notch (hole) |
Separates the medial and middle third of the supraorbital margin |
Supraorbital nerve (branch of the frontal nerve from the optic nerve - V1) |
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Front lattice hole |
24 mm from the medial edge of the orbit at the level of the fronto-ethmoid suture |
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Rear lattice hole |
12 mm behind the anterior lattice foramen, 6 mm from the optic foramen |
The eponymous neurovascular bundle |
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Zygomatic bone openings |
Zygomaticofacial and zygomatic neurovascular bundles |
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Nasolacrimal canal |
It starts in the lacrimal sac and opens into the inferior nasal passage under the inferior turbinate |
The duct of the same name |
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Infraorbital foramen |
Located 4-10 mm below the infraorbital margin |
Infraorbital neurovascular bundle (from V2) |
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Visual channel |
Diameter 6.5 mm, length 10 mm |
Optic nerve, ocular artery, sympathetic fibers |
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Superior orbital fissure |
Length 22 mm. Limited by the large and small wing of the sphenoid bone. Located below and lateral to the optic opening. Divided by the leg of the lateral rectus muscle into two parts: external and internal |
External: superior ocular vein, lacrimal, frontal, trochlear nerves; Internal: upper and lower branches of the oculomotor nerve, naso-ciliary nerve, abducens nerve; sympathetic and parasympathetic fibers |
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Inferior orbital fissure |
Formed by the sphenoid, zygomatic and palatine bones, upper jaw |
Infraorbital and zygomatic nerves (V2), inferior ocular vein |
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Wedge-frontal foramen (non-permanent) |
Wedge-frontal suture |
Recurrent meningeal artery anastomosed with the lacrimal artery |
Anatomical structures of the orbit
The orbit is a bone receptacle 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 lifting the upper eyelid, fascial formations, and blood vessels pass.
In front (with the eyelids closed), the orbit is limited by the tarsoorbital fascia, woven into the cartilage of the eyelids and fused 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 node ( ganglion ciliare) with a size of 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 node 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 \u200b\u200bbone 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 lower oblique. It originates from the lower bone wall of the orbit, near the inlet of the nasolacrimal canal.
In addition to the periosteum, the fascia of the orbit, according to the International Anatomical Nomenclature, includes the vagina of the eyeball, muscle fascia, the orbital septum and the fatty body of the orbit ( corpus adiposum orbitae).
The 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 site of the optic nerve. The greatest density and thickness of this fascia is noted in the region of the equator of the eye, where the tendons of the oculomotor muscles pass through it on the way to the places of attachment to the surface of the sclera. As you approach the limbus, the vaginal tissue becomes thinner and eventually is gradually lost in the subconjunctival tissue. In places of suppression by extraocular muscles, it gives them a fairly dense connective tissue coating. Dense strands also depart from the same zone ( fasciae musculares) connecting the vagina of the eye with the periosteum of the walls and edges of the orbit. In general, these cords form an annular membrane that is parallel to the equator of the eye and keeps it in a stable position in the orbit.
Subvaginal space of the eye (formerly - spatium Tenoni) is a system of slits in loose episcleral tissue. It provides free movement of the eyeball in a certain volume. This space is often used for surgical and therapeutic purposes (performing implantation-type sclero-strengthening operations, administering drugs by injection).
Orbital septum (septum orbitale) - a well-defined structure of the fascial type, located in the frontal plane. Connects the orbital edges of the eyelid cartilage 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 region of the medial wall of the orbit, this septum, which is also called the tarzoorbital 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 cavity of the orbit is filled with a fatty body ( corpus adiposum orbitae), which is enclosed in a thin aponeurosis and is penetrated by connective tissue bridges, dividing it into small segments. Due to its plasticity, the adipose tissue does not interfere with the free movement of the oculomotor muscles passing through it (when they contract) and the optic nerve (when the eyeball moves). The fatty body is separated from the periosteum by a slit-like space.
CT and MR anatomy
The bony walls of the orbit are clearly visualized on CT-cuts, forming the figure of a truncated cone, with its apex facing the base of the skull. It should be borne in mind that the computer integrated into the tomograph is not able to build an image of bone structures less than 0.1 mm thick.
Therefore, in some cases, the images of the medial, lower and upper walls of the orbit are intermittent in nature, which can mislead the doctor. The small size of the bone "defect", the absence of angular displacements of the edges of the "fracture", the disappearance of the discontinuity of the contour on the following sections make it possible to distinguish such artifacts from a fracture.
Due to the low content of hydrogen protons, the bone walls of the orbit are characterized by a pronounced hypointense signal on T1 and T2-weighted images and are poorly distinguishable on MRI.
Fatty body of the eye socket it is clearly visualized on both CT (density 100 HU) and MRI, where it gives a hyperintense signal on T2- and low - on T1-WI.
Optic nerve at CT has a density of 42–48 HU. On ultrasound, it is visualized as a hypoechoic strip. MRI allows you to trace the optic nerve all the way up to the chiasm. Axial and sagittal planes with fat suppression are especially effective for its visualization along the entire length. The subarachnoid space surrounding the optic nerve is better visualized on T2-WI with fat suppression in the frontal 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 leaving her.
The shell of the eyeball when ultrasound and CT are visualized as a whole. The density is 50-60 HU. With MRI, they can be differentiated by the intensity of the MR signal. The sclera has a hypointense signal on T1- and T2-WI and looks like a clear dark stripe; the choroid and retina are hyperintense on T1-WI and on proton density-weighted tomograms.
Extraocular muscles on MRI tomograms the signal intensity significantly differs from retrobulbar tissue, as a result of which they are clearly visualized throughout. At CT, 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 straight - 2.9 ± 0.6 mm, the medial straight - 4.1 ± 0.5 mm, lower straight line - 4.9 ± 0.8 mm.
A number of pathological conditions are accompanied by thickening of the oculomotor muscles
- Trauma-related causes include:
- contusion edema,
- intramuscular hematoma,
- orbital cellulite as well
- carotid-cavernous and
- dural-cavernous fistula.
- By the way -
- endocrine ophthalmopathy,
- pseudotumor of the orbit,
- lymphoma,
- amyloidosis,
- sarcoidosis,
- metastatic tumors, etc.
Superior ocular vein on axial sections it has a diameter of 1.8 ± 0.5 mm, coronal - 2.7 ± 1 mm. Expansion of the superior ocular vein revealed 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 enlargement of the superior ocular vein and, finally, endocrine ophthalmopathy.
The blood in the paranasal sinuses has a density of 35-80 HU, depending on the duration of the hemorrhage. Inflammatory processes often lead to a limited accumulation of fluid and look like a parietal or polypoid thickening of the mucous membrane with a density of 10-25 HU. Frequent radiological symptoms of fracture of the orbital walls bordering the paranasal sinuses are emphysema of the orbit and paraorbital tissues, as well as pneumocephalus.
Superior orbital fissure, connecting the orbit with the cranial cavity, is located between the upper and outer walls of the orbit, lateral to the optic nerve canal. Its size is 3x22 mm. It is divided by two tendons of extraocular muscles into the upper, or lateral, and lower, or medial, parts.
Through it, into orbit enter ocular and oculomotor nerves... The first, within the cleft, is divided into three branches: the lacrimal and frontal nerves are located in the lateral part of the cleft, the nasal nerve passes through its medial section. The block nerve is located medial to the frontal.
Oculomotor nerve within the cleft, it is also divided into two branches: the upper, located between the trochlear and nasal nerve, and the lower, passing at the medial edge of the cleft. Through the upper orbital fissure, the upper ocular and sometimes the lower optic veins emerge: the first from the orbit through the upper part, the second through the lower.
Slit tightened by a connective tissue membrane - a very unreliable defense against the spread of a tumor or inflammatory process in both directions.
Inferior orbital fissure located between the bottom and outer walls at a distance of 10 mm (options from 2 to 12 mm are possible) from the outer orbital edge. It connects the orbit with the pterygopalatine and infratemporal fossa. In malignant tumors of the orbit, early spread of the process to both the pterygopalatine and temporal fossa is possible, which is extremely important to consider when planning treatment and carrying out exenteration of the orbit.
Through inferior orbital fissure passes the infraorbital artery and the nerve of the same name, and also enters the zygomatic nerve, perforating periorbitis. The inferior orbital fissure is the gateway of the anastomosis of the venous system of the orbit with the venous plexuses of the pterygopalatine fossa and the deep vein of the face. These features are important, especially during the surgical treatment of phlegmon and orbital abscesses.
Periorbita It is firmly connected to the underlying walls of the orbit only in the area of \u200b\u200bbone sutures and along the edges of natural openings, for the rest of the length it adjoins the walls, forming a slit-like subperiosteal space. Naturally, during orbital operations, if manipulations in the nodperiosteal space are necessary, the surgeon must remember the places of close contact of the periorbital and adjacent bones.
Bone volume orbits the average is 23 cm3 in women and 26 cm3 in men, 80% of the volume is occupied by the neuromuscular apparatus, blood vessels, adipose tissue, and only 20% - by the eye itself. Studying the Pirogov sections, P.I.Kolesnikov determined the distance of the eye from the walls of the orbit: from the upper wall - by 6.7 mm, from the outer wall - by 6.3, from the bottom - by 9.5, from the inner - by 9 mm. It would seem that a significant distance of the eye from the superior and inner walls of the orbit makes these zones more accessible for palpation of the retrobulbar space.
However, in the upper section it difficult due to the overhanging upper orbital edge (concave position of the upper orbital wall).
The lower section is more accessible to palpation orbits, since the concavity of the lower wall of the orbit is much less. In front, starting from the orbital edge, merging along the edge with the periosteum, is the fifth "wall" of the orbit - the tarzoorbital fascia (septum orbitae), which in the eyelids is woven into the edge of the cartilage of the upper and lower eyelids. Thus, everything that lies behind the tarso-orbital fascia belongs to the orbital cavity.
1 - sutura sphenozygomatica,
2 - sutura sphenofrontalis,
3 - sutura sphenoethmoidalis,
4 - external geniculate body (tubing),
5 - large wing of the sphenoid bone,
6 - small wing of the sphenoid bone,
7 - the body of the sphenoid bone,
8 - palatine bone,
9 - upper jaw,
10 - visual aperture,
11 - upper orbital fissure,
12 - rear lattice hole,
13 - infraorbital groove,
14 - round hole.
From the standpoint of craniofacial surgery, the orbit is usually divided into three zones -
- the external orbit (consisting of the zygomatic bone and the nasoethmoidal complex, i.e., the frontal process of the upper jaw, the nasal part of the frontal bone, nasal, lacrimal and ethmoid bones),
- internal orbit and starting from the anterior edge of the inferior orbital fissure
- deep orbit (its apex), formed by the sphenoid bone and occupying 20% \u200b\u200bof the orbital volume.
The infraorbital nerve, the inferior orbital fissure, the orbital process of the perpendicular plate of the palatine bone and the large wing are the identification points (boundaries) of the apex of the orbit.
sphenoid bone. The place of confluence of the four anatomical identification points of the deep orbit listed above is called the orbital drain (confluens orbitae).
Inferior orbital fissure (fissura orbitalis inferior) is a continuationfrom top to bottom of the superior orbital fissure. Separates the lateral and inferior walls. Its anterior sections open into the infratemporal fossa, the posterior ones - into the pterygo-palatine fossa located behind the maxillary sinus. Above the gap is limitedthe orbital surface of the greater wing of the sphenoid bone, from below - the orbital plate of the upper jaw, the zygomatic bone and the orbital process of the perpendicular plate of the palatine bone.
The length of the lower orbital fissure is about2 cm, width varies from 1 to 5 mm. Front end of the slitlocated 20 (and sometimes 6-15!) mm from the infraorbital edge and isthe boundary of the lower wall of the orbit. The lumen of the lower orbital fissure is closed by a connective tissue septum, into which smooth muscle fibers are woven - the so-called orbital muscle (m. Orbitalis) of Müller, which receivessympathetic innervation.
Possibility of quite close proximitythe inferior orbital fissure to the edge of the orbit should be considered when reconstructing "explosive" orbital fundus fractures. Spliced \u200b\u200bwith edgescracks, a sufficiently dense periosteum can be mistaken forsoft tissues restrained in the fracture zone, and occurring in 42% of casesclavate expansion of the anterior edge of the gap - beyond the fracture zone. An attempt to separate the periosteum from the edges of the lower orbital fissure is fraught withsevere bleeding from the infraorbital artery.
Contents of the inferior orbital fissure:
- maxillary nerve (n. maxillaris, V2);
- zygomatic nerve (n. zygomaticus) and its branches: zygomatic facial (r. zygomaticofacialis) and zygomatic (r. zygomatico-temporalis), giving through anastomosiswith the lacrimal nerve, secretory fibers for the lacrimal gland;
- infraorbital nerve (n. infraorbitalis) and the artery of the same name (a. infraorbitalis);
- small orbital branches of the pterygopalatine ganglion (ganglion pterygopalatinum);
- a branch or branches of the inferior ophthalmic vein draining into the pterygoid venousplexus and deep vein of the face. Thus, the venous network of the face,the pterygoid-palatine fossa, paranasal sinuses and cavernous sinus make up a single whole. It should be noted that with purulent-inflammatorydiseases of the deep tissues of the face, paranasal sinuses and facial bonesskull infection through the lower ocular vein can enter the cavernoussinus and cause thrombosis.
Behind the confluence of the superior and inferior orbital fissures on the outer base of the skull there is a hole of the correct rounded shape - round hole (foramen rotundum), connecting the middle cranial fossa with the pterygo-palatine fossa (next to the orbit) and intended for the passage of the second branch of the trigeminal nerve - the maxillary nerve (n. maxillaris).
The apex of the orbit has two apertures - the optic opening and the superior orbital fissure.
The optic foramen is located in the upper medial part of the apex of the orbit along an imaginary horizontal line passing through the anterior and posterior ethmoid foramen, approximately 6 mm behind the latter. The optic opening is surrounded by a common Cinna tendinous ring (annulus tendineus communis Zinni), from which all rectal oculomotor muscles begin.
Visual channel (canalis opticus) has a diameter of 6.5 mm and a length of 8-10 mm. Directed at an angle of 45º inward and 15º upward.
- The lateral canal wall is formedtwo roots of the lesser wing of the sphenoid bone and makes up the inner wallupper orbital fissure.
- The medial wall of the optic canal is formed by the body of the sphenoid bone and has a thickness of no more than 1 mm.
- The upper wall of the canal 2-3 mm thick is the bottom of the anterior cranial fossa.
Orbital opening of the canalhas a vertical oval shape, the middle part is round, the intracranial opening is a horizontal oval section. This is due to the arcuate strokeocular artery. In addition to the optic nerve and the ocular artery, the sympathetic fibers of the carotid plexus are located in the canal.
Superior orbital fissure
(fissura orbitalis superior) - is the border between the upper and lateral walls of the orbit. Formed by the body and wings of the sphenoid bone, it connects the cavity of the orbit with the middle cranial fossa, tightened by a connective tissue membrane.
IN slots distinguish twoparts -
- inner or bottom (wider, obliquely vertical,intraconal, i.e., opening into the muscle funnel) contains:
- nasociliary nerve (n. nasociliaris from n. ophthalmicus);
- abducens nerve (n. abducens, n. VI)
- sympathetic and parasympathetic fibers;
- the upper and lower branches of the oculomotor nerve (n. oculomotorius, n. III).
- external (upper, more narrow, going obliquely horizontally anteriorly-upward extraconal). FROMpossesses (by direction from outside to inside):
- lacrimal nerve (n. lacrimalis) from the first branch (n. ophthalmicus) of the trigeminalnerve;
- a branch of the middle meningeal artery;
- superior ocular vein;
- frontal nerve (n. frontalis) from the first branch (n. ophthalmicus) of the trigeminalnerve;
- trochlear nerve (n. trochlearis); extraconal localization of the block nerveexplains the preservation of some mobility of the eyeball even afterimpeccably performed retrobulbar anesthesia.
The border between them is a bony protrusion in the middle of the lowerthe edges of the orbital fissure (spina recti lateralis), from which the lateralthe leg of the lateral rectus muscle.
The length of the superior orbital fissure is 22 mm on average. The width of the gap varies significantly, which is the anatomical prerequisite for the development of the syndrome of the same name.
The lumen of the superior orbital fissure contains many extremely important anatomical structures:
- ophthalmic nerve (n. ophthalmicus) - the first branch of the trigeminal nerve,providing sensitive innervation of all structures of the orbitalorganocomplex. Usually already within the upper orbital fissure of the opticthe nerve is divided into three main branches - lacrimal (n. lacrimalis), frontal(n. frontalis) and naso-ciliary (n. nasociliaris);
- all motor nerves of the orbit - oculomotor (n. oculomotorius),block (n. trochlearis) and discharge (n. abducens);
- superior ocular vein (v. ophthalmica superior) or ocular venous sinus,formed by the fusion of the superior and variable inferior ocular veins;
- occasionally the gap contains the already mentioned recurrent meningealartery a. meningea recurrens, which often occupies the most lateralposition.
- even less often, the central retinal vein passes through the slit (in thosecases when it does not flow into the superior ocular vein, but directlyinto the cavernous sinus).
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The eyeball is located in the bone receptacle - the orbit (orbita). The eye socket has the shape of a truncated tetrahedral pyramid, the top 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, external and internal), three of which (internal, 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 tissues of the orbit. The lower wall is most often exposed to blunt trauma (contusion); as a result of this, a downward displacement of the eyeball can occur, limiting its mobility upward and outward with infringement of the lower oblique muscle (m. obliquus inferior).
Top wall formed by the frontal bone, in the thickness of which there is a sinus (sinus frontalis), and a 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, the tendon of the superior oblique muscle (lig.m, obliqui superioris) passes through it. In the frontal bone above and outside there is a fossa of the lacrimal gland (fossa glandulae lacrimalis). The superior wall of the orbit is on the border with the anterior cranial fossa, which is very important to consider in trauma.
Inner wallformed: from below - by the upper jaw and palatine bone; from above - a part of the frontal bone; behind - sphenoid bone; in front - the lacrimal bone and the frontal process of the upper jaw.
In the lacrimal bone there is a posterior lacrimal crest, in the frontal process of the upper jaw - an anterior lacrimal crest. Between them there is a recess - the fossa of the lacrimal sac (fossa sacci lacrimalis), in which the lacrimal sac (saccus lacrimalis) is located. Fossa size 7x13 mm; at the bottom, it passes into the nasolacrimal duct (ductus nasolacrimalis) 10-12 mm long, which runs in the wall of the maxillary bone and ends 2 cm posterior to the anterior edge of the inferior turbinate. If the wall is damaged, emphysema of the eyelids and orbits develops.
The inner, upper and lower walls of the orbit are bordered by the paranasal sinuses, which often causes the spread of inflammation and tumor process from them into the orbital cavity.
Outer wall - the most durable; it is formed by the zygomatic, frontal and large 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).
Figure: 1. The structure of the orbit
Visual channel (canalis opticus) - bone canal with a round hole 4 mm in diameter. Through it, the orbit communicates with the cranial cavity. The optic nerve (n. Opticus) and the ocular artery (a. Ophtalmica) 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 is connected 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. Ophtalmicus) - n. lacrimalis, n. nasoclliaris, n. frontalis, as well as the oculomotor nerve (n. oculomotorius); the superior ocular vein (v. ophtalmica superior) comes out of the orbit through this slit. If the superior orbital fissure is damaged, a complex of symptoms of the same name develops: complete ophthalmoplegia (lack of eyeball movement), ptosis (drooping of the upper eyelid), mydriasis (dilation of the pupil), disorder of tactile sensitivity, dilated retinal veins, exophthalmos (standing 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), innervated by sympathetic nerve fibers, are interwoven. One of the two branches of the lower optic vein (v. Ophtalrmca interios) leaves through this slit, and enters the orbit n. infraorbitalis and a. infraorbitalis, n. zygomaticus and rr. orbitalis from the pterygopalatine node (gangl. pterygopalatinum).
Front and rear louvers (foramen ethmoidale anterius et posterius) - holes in the lattice plates. Nerves of the same name, arteries and veins (branches of the nasal 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 - n passes through it. n.andibularis (III branch of n. trigeminis).
On the inside, the orbit is covered with the periosteum (periorbita), which is tightly fused with the bones forming it in the canalis opticus region. Here is the tendon ring (annulus tendineus communis Zinni), in which all the oculomotor muscles begin, except for the lower oblique.
To the fascia of the eye socketin addition to the periosteum include:
- the vagina of the eyeball (vag.bulbi);
- muscle fascia (fasciae musculares);
- orbital septum (septum orbitale);
- the fatty body of the orbit (corpus adiposum orbitae).
The vagina of the eyeball (vagina bulbi s. Tenoni) covers the entire eyeball, except for the cornea and the exit site n. opticus. Its thickest part (2.5-3.0 mm) is located in the equator of the eye, where the tendons of the oculomotor muscles pass, which acquire a dense connective tissue sheath here. From the equatorial zone, dense strands also extend, connecting the tenon capsule with the periosteum of the walls and the edges of the orbit, thus creating a membrane that fixes the eyeball in the orbit. Under the eyeball is the Lockwood suspension ligament, which is essential in keeping 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, implantation of transposition materials for therapeutic purposes).
The orbital septum (septum orbitae) is the fifth movable wall of the orbit that limits the cavity of the orbit when the eyelids are closed. It is formed by the fasciae that connect the orbital edges of the eyelid cartilage to the bony edges of the orbit. The cavity of the orbit 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 top to its base.
Blood supply
The ophthalmic artery (a. Ophtalmica) enters the orbit through the optic opening (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);
- muscle arteries (aa. musculares).
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