Orbit Flashcards
Anatomy (Dimensions)
Volume of orbital cavity is about —— in an adult
Rim of the orbit measures — mm
horizontally and — mm vertically in an adult
Medial orbital walls are roughly parallel and —mm apart in adults
Lateral orbital walls angles about ——degrees from each other
Anatomy (Dimensions)
Resembles a four sided pyramid
Volume of orbital cavity is about 30 cc in an adult
Rim of the orbit measures 40 mm
horizontally and 35 mm vertically in an adult
Medial orbital walls are roughly parallel and 25 mm apart in adults
Lateral orbital walls angles about 90 degrees from each other
Orbital
• Superior orbital rim is formed by the ——— bone
• Inferior orbital rim is formed by —— bone medially and —— bone laterally
© Lateral orbital rim is formed by the ——
• Superior orbital rim contains a notch at its —— and —— 1/3. This is known as ——- notch.
• ——— passes through this notch to the forehead
© Medial portion ofthe rim is formed by the ———
Orbital
• Superior orbital rim is formed by the frontal bone
• Inferior orbital rim is formed by maxillary bone medially and zygomatic bone laterally
© Lateral orbital rim is formed by the zygoma
• Superior orbital rim contains a notch at its medial and lateral 1/3. This is known as supraorbital notch.
• Supraorbital nerve and artery passes through this notch to the forehead
© Medial portion ofthe rim is formed by the frontal process of maxilla
Lacrimal fossa
Lodges the ———
This fossa is formed by —— and —— bones
It is bounded by ——- and ——-
Lodges the lacrimal sac
• This fossa is formed by maxillary and lacrimal bones
It is bounded by anterior and posterior lacrimal crests
Anterior lacrimal crest is formed by the maxillary bone
Posterior lacrimal crest is formed by lacrimal bone
Lacrimal fossa
Anterior lacrimal crest is formed by the ——— bone
Posterior lacrimal crest is formed by —— bone
Anterior lacrimal crest is formed by the maxillary bone
Posterior lacrimal crest is formed by lacrimal bone
Anterior lacrimal crest is formed by the maxillary bone
Posterior lacrimal crest is formed by lacrimal bone
Naso lacrimal duct
Connects the ——— to the ——— opening in the ——— of nose
It is—to—mm in diameter
It is about —mm long
All the walls of the duct are covered with
——- bone excepting its —— wall
The medial wall is formed by———inferiorly and ——— superiorly
Naso lacrimal duct
Connects the lacrimal sac to the naso
lacrimal opening in the inferior meatus of nose
It is 3-4 mm in diameter
It is about 12 mm long
All the walls of the duct are covered with
maxillary bone excepting its medial wall
The medial wall is formed by lateral nasal wall inferiorly and descending process of lacrimal bone superiorly
Weber’s suture
It lies anterior to the ———
Also known as ————
This suture runs parallel to———
Branches of ——- artery pass through this groove to supply the nasal mucosa
Bleeding occurs from these vessels during lacrimal sac surgeries
Weber’s suture
It lies anterior to t h e lacrimal fossa
Also known as sutura longitudinalis imperfecta
This suture runs parallel to anterior lacrimal crest
Branches of infraorbital artery pass through this groove to supply the nasal mucosa
Bleeding occurs from these vessels during lacrimal sac surgeries
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Embryology
The 7 bones forming the orbit are derived from ——- cells
• Ossification of orbit is complete at —— excepting its ——
Excepting ———-, other bones develop by ———- ossification
Embryology
The 7 bones forming the orbit are derived from neural crest cells
• Ossification of orbit is complete at birth excepting its apex
Excepting lesser wing of sphenoid other bones develop by intramembranous ossification
Lesser wing of sphenoid is cartilaginous
Embryology
Excepting lesser wing of sphenoid other bones develop by ——— ossification
Lesser wing of sphenoid is ———
Embryology
Excepting lesser wing of sphenoid other bones develop by intramembranous ossification
Lesser wing of sphenoid is cartilaginous
Orbital roof
The roof is formed by the ——— bone
The posterior —cm of the roof is formed by the ——-
The optic foramen is located in the ———
The optic foramen contains the ——
The optic nerve enters the orbit at an angulation of — degrees
Lacrimal gland is located at the ———
• Trochlear fossa is located in the ————
Orbital roof
The roof is formed by the frontal bone
The posterior 1.5 cm of the roof is formed by the lesser wing of sphenoid
The optic foramen is located in the lesser wing of sphenoid
The optic foramen contains the optic nerve
The optic nerve enters the orbit at an angulation of 45 degrees
Lacrimal gland is located at the lateral end of orbital roof
• Trochlear fossa is located in the anteromedial portion of the roof
Medial orbital wall
Is formed by the ———
Thinnest portion of the medial wall is the ———-. It is one of the components of the —— bone
• Infections from ——— sinus can breach this bone thus spreading to the
orbit
Medial orbital wall
Is formed by the frontal process of maxilla, lacrimal bone, ethmoidal bone, and lesser wing of sphenoid bone
Thinnest portion of the medial wall is the lamina papyracea. It is one of the components of the ethmoid bone
• Infections from ethmoidal sinus can breach this bone thus spreading to the
orbit
Medial orbital wall (contd)
• The medial orbital wall is thicker posteriorly where the ——— bone is present. It is thicker anteriorly where the ———— is present
• Tumors of the nasal cavity can breach the ——— to involve the orbit
• A ——— line runs between the anterior and posterior lacrimal crests
Medial orbital wall (contd)
• The medial orbital wall is thicker posteriorly where the sphenoid bone is present. It is thicker anteriorly where the posterior lacrimal crest is present
• Tumors of the nasal cavity can breach the lamina papyracea to involve the orbit
• Avertical suture line runs between the anterior and posterior lacrimal crests
• Avertical suture line runs between the anterior and posterior lacrimal crests
• If this suture is located anteriorly it indicates predominance of —— bone while a posteriorly located suture indicates the predominance of —— bone in the anatomical relationship
Medial orbital wall (contd)
• The medial orbital wall is thicker posteriorly where the sphenoid bone is present. It is thicker anteriorly where the posterior lacrimal crest is present
• Tumors of the nasal cavity can breach the lamina papyracea to involve the orbit
• Avertical suture line runs between the anterior and posterior lacrimal crests
• If this suture is located anteriorly it indicates
predominance of lacrimal bone while a posteriorly located suture indicates the predominance of maxillary bone in the anatomical relationship
Medial wall applied anatomy
Lacrimal bone at the level of ——-is very thin
• This bone can easily be penetrated during ———
If —— component is
predominant, it becomes difficult to perform osteotomy to reach the sac
during endo DCR because——-
MedialIwall applied anatomy Lacrimal bone a t the level of lacrimal
fossa
is very thin
• This bone can easily be penetrated during endoscopic DCR
If maxillary component is
predominant, ti becomes difficult to perform osteotomy to reach the sac
during endo DCR because the maxillary bone is very thick
Fronto ethmoidal suture line
This is a very important surgical landmark
This suture line marks the approximate level of ———
Dissection above this line will expose the cranial cavity
——— and ——— foramina are present in this suture line
Anterior ethmoidal foramen is located — mm from the ——— lacrimal crest, while the posterior foramen is located — m m from the ———lacrimal crest
The ——— and ——— arteries pass through these foramina
Fronto ethmoidal suture line
This is a very important surgical landmark
This suture line marks the approximate level of ethmoidal sinus roof
Dissection above this line will expose the cranial cavity
Anterior and posterior ethmoidal foramina are present in this suture line
Anterior ethmoidal foramen is located 24 mm from the anterior lacrimal crest, while the posterior foramen is located 36 m m from the anterior
lacrimal crest
The anterior and posterior ethmoidal arteries pass through these foramina
Orbital floor
It is bordered laterally by ——— fissure
Medially it is bound by the ———
The floor is almost entirely formed by the ————, while the ———bone contributes to a small portion posteriorly
Orbital floor
1Floor is the shortest of all its walls
It is bordered laterally by infraorbital fissure
Medially it is bound by the maxillo ethmoidal strut of bone
The floor is almost entirely formed by the orbital plate of maxilla, while the orbital plate of palatine bone contributes to a
small portion posteriorly
The ——- is the shortest of all the orbit walls
Floor
Orbital floor (contd)
• Infraorbital groove becomes ——— foramen anteriorly
———— pass through this foramen
- The portion of the floor medial to the infraorbital groove is thin because of the———
Orbital floor (contd)
• Infraorbital groove becomes infraorbital foramen anteriorly
Infraorbital nerve and artery pass through this foramen
- The portion of the floor medial to the infraorbital groove is thin because of the expansion of the maxillary sinus
Orbital floor (contd)
• ———— becomes infraorbital foramen anteriorly
- The portion of the floor medial to the infraorbital groove is(thin/thick?) because of the expansion of the maxillary sinus
Orbital floor (contd)
• Infraorbital groove becomes infraorbital foramen anteriorly
Infraorbital nerve and artery pass through this foramen
- The portion of the floor medial to the infraorbital groove is thin because of the expansion of the maxillary sinus
Lateral wall
• Lateral wall of orbit is formed by the ————
- ——— and ——— bone contribute in a minor way anteriorly
——— branch of ——-artery is seen in this wall
— to — mm behind the lateral orbital rim and — cm inferior to the fronto zygomatic suture line ——— tubercle is present.
Lateral wall
• Lateral wall of orbit is formed by the greater wing of sphenoid
- Zygoma and zygomatic process of frontal bone contribute in a minor way anteriorly
Recurrent meningeal branch of middle meningeal artery is seen in this wall
4 - 5 mm behind the lateral orbital rim and
1 cm inferior to the fronto zygomatic suture line Whitnall’s
tubercle is
present.
Whitnall’s tubercle
• Lies — to — mm behind the ——— rim & — cm inferior to ———— suture
Structures getting attached to this tubercle are:
Whitnall’s tubercle
• Lies 4-5 mm behind the lateral orbital rim & 1 cm inferior to fronto zygomatic suture
Structures getting attached to this tubercle are: 1. Lateral canthal tendon
2. Lateral rectus check ligament
3. Suspensory ligament of lower eyelid (Lockwood’s ligament)
4. Orbital septum
5. Lacrimal gland fascia
Lateral wall (contd)
• ———— and ——— bone protect the globe from lateral trauma
• This area is also known as ——— area
• Just behind this facial buttress area the ——— bone and ———bone are thinner. The junction between these two bones are separated by the ——— suture.
This area is the preferred site for ———
Posteriorly lateral wall thickens and meet the —— bone to form the lateral wall of the cranial cavity
Lateral wall (contd)
• Frontal process of zygoma and zygomatic process of frontal bone protect the globe from lateral trauma
• This area is also known as facial buttress area
• Just behind this facial buttress area the posterior zygomatic bone and orbital plate of greater wing of sphenoid are thinner. The junction between these two bones are separated by the zygomatico sphenoid suture.
This area is the preferred site for lateral orbitotomy Posteriorly lateral wall thickens and meet the temporal
bone to form the lateral wall of
the cranial cavity
Superior orbital fissure
Lies between the ——— and ——— of ——- bone
Medial to this fissure is the ——— through which ——- passes
-what passes through this fissure
outside the annulus of zinn
Superior orbital fissure
Lies between the greater and lesser wings of sphenoid
Medial to this fissure is the optic foramen through which optic nerve passes
Lacrimal, frontal and trochlear nerves pass
through this fissure
outside the annulus of zinn
Optic foramen
• Lies medial to the ———— fissure
• It is present in the —— wing of sphenoid
• ———— passes through it
• It is about —mm in diameter
Optic foramen in both sides is usually
Asymmetrical (T or F) .
Optic foramen
• Lies medial to the superior orbital fissure
• It is present in the lesser wing of sphenoid
• Optic nerve and ophthalmic artery passes through it
• It is about 6.5 mm in diameter
Optic foramen in both sides is usually
symmetrical. Even slight difference is considered to be pathological
Inferior orbital fissure
• Lies between the ——— and ———
• It is about — mm long
Structures passing through this fissure are:
Inferior orbital fissure
• Lies between the lateral wall and floor of orbit
• It is about 20 mm long
Structures passing through this fissure are:
.1 Maxillary division of trigeminal nerve
2. Zygomatic nerve
3. Branches from sphenopalatine ganglion
4. Branches from inferior ophthalmic vein leading on to pterygoid plexus
Soft tissues of orbit include:
Soft tissues of orbit
• Orbitalseptum
• Periorbita
• Orbital fat
• Extraocular muscles
• Lacrimal system
Orbital septum
It is ——— in origin
• Covered anteriorly by ——— muscle
Orbital septum
Is the anterior soft tissue boundary of orbit
• It acts as a physical barrier against pathogens
It is thin and formed by multilayered fibrous tissue
It is mesodermal in origin
• Covered anteriorly by preseptal orbicularis oculi muscle
——— Is the anterior soft tissue boundary of orbit
Orbital septum
Periorbita
Is the ——— lining of orbital walls
Posteriorly the Periorbita is continuous with the ——-
———— provides the cushioning effect to the eye ball
Periorbita
Is the periosteal lining of orbital walls
It is attached to fissures, suture lines and foramen of orbit
Posteriorly the Periorbita is continuous with the optic sheath
Fat tissue / orbital fat provides the cushioning effect to the eye ball
———Is the periosteal lining of orbital walls
Periorbita
Is the periosteal lining of orbital walls
It is attached to fissures, suture lines and foramen of orbit
Extraocular muscles
Arise from ———-
These muscles
are:
Extraocular muscles
Arise from the annulus of zinn
• They are responsible for the movements of the globe
These muscles
are:
1. Lateral and medial rectus 2. Superior and inferior rectus
3. Superior and inferior oblique
Lacrimal system
Lacrimal gland is located in the ——— portion of orbit
It lies in the shallow ——— of frontal bone
• It is composed of numerous secretary units called ——-, It measures —mm / —mm
A fibrous band incompletely divides the gland in to two lobes, the posterior larger —— lobe and the anterior smaller —— lobe
Ducts from the —— lobe will have to pass through the —— lobe to drain
Damage to the —— lobe blocks drainage to the entire gland
Lacrimal system
Lacrimal gland is located in the supero temporal portion of orbit
It lies in the shallow lacrimal fossa of frontal bone
• It is composed of numerous secretary units called acini It measures 20mm / 12mm
A fibrous band incompletely divides the gland in to two
lobes, the posterior larger orbital lobe and the anterior smaller palpebral lobe
Ducts from the orbital lobe will have to pass through the palpebral lobe to drain
Damage to the palpebral lobe blocks drainage to the entire gland
Lacrimal system (contd)
The lacrimal excretory system begins at the —— end of each eyelid known as the ——
These puncta are directed ———
Punctal opening widens into ———, which is perpendicular to the eyelid margin
This makes a sharp turn to drain into the ———
The canaliculi measures —to — mm in diameter
• It courses parallel to the ———
Lacrimal system (contd)
The lacrimal excretory system begins at the medial end of each eyelid known as the punctum
These puncta are directed posteriorly
Punctal opening widens into ampulla, which is perpendicular to the eyelid margin
The ampulla makes a sharp turn to drain into the canaliculi
The canaliculi measures 0.5 - 1 mm in diameter • It courses parallel to the lid margins
Lacrimal system (cont)
Superior canaliculus is — mm long
Inferior canaliculus is — mm long
These two canaliculi joint to form a common canaliculi before joining the
sac
Opening of common canaliculi into nasolacrimal sac is known as ——
———- is present at the junction of the common canaliculus and the lacrimal sac
———— is present at the lower end
of nasolacrimal duct at the ———
Congenital nasolacrimal duct obstruction is caused due to imperforate ————
Lacrimal system (cont)
Superior canaliculus is 8 mm long
Inferior canaliculus is 10 mm long
These two canaliculi joint to form a common canaliculi before joining the
sac
Opening of common canaliculi into nasolacrimal sac is known as internal punctum
Valve of Rosenmuller is present at the junction of the common canaliculus and the lacrimal sac
Hasner’s valve is present at the lower end
of nasolacrimal duct at the inferior m e a t s
Congenital nasolacrimal duct obstruction is caused due t o imperforate Hasner’s valve
Nasolacrimal sac
Resides in the ———
Measures about — - — mm vertically
— to —mm anteroposteriorly
• Drains via the ———duct into the ———
Resides in the lacrimal fossa
Measures about 12 - 15 mm vertically
4-8mm anteroposteriorly
• Drains via the nasolacrimal Lacrimal
duct into the inferior meatus
Development of orbit
Develops from mesenchyme by ——
— th to — th week laying down of bones starting with —— bone around the Optic vesicle
During this time optic vesicle —degree apart rotates anteriorly
Development of orbit
Develops from mesenchyme by ossification
6 th to 7 th week laying down of bones starting with maxilla bone around the Optic vesicle
During this time optic vesicle 170 degree apart rotates anteriorly
Craniosfacial dysostois / Crouzon’ syndrome features:
Proptosis – shallow orbits
Hypertelorim - wide separation of orbits
V pattern exotropia
Oxycephaly-syndactlye / Apert’ syndrome features
Oxycephaly-syndactlye /
Apert’ syndrome
:
Flattened occiput , steep forehead , supra orbital ridge
Midfacial hypoplasia , parrot beak nose
Orbital apex syndrome/ Tolosa - hunt syndrome :
Damage to structures at ———
Symptoms :
Orbital apex syndrome
/ Tolosa - hunt syndrome :
Damage to structures at apex 2 nd, 3 rd, 4 th ,6 th nerves
Symptoms : visual loss, ophthalmoplegia periorbital & facial pain
———— Lesion anterior to orbital apex excluding optic nerve pathology
Superior orbital fissure syndrome
/ Rochon – Duvigneaud syndrome :
Lesion anterior to orbital apex excluding optic nerve pathology
Contents of orbit include
Contents of orbit
Eye ball
Orbital fat
Connective tissue system
Blood vessels
Nerves
Extraocular muscles
Connective tissue system include
Connective tissue system
Periorbita Orbital septum Tenon’s capsule
Which of the facial system is incompletely formed
Posterior facial system
Anterior fascialsystem
Formed by condensation of fibrous septa:
Anterior fascialsystem
Formed by condensation of fibrous septa:
Lockwood lig,
whitnall sup susp lig
Lacrimal lig
Intermuscular septum
Surgical spaces in orbit :
Surgical spaces in orbit :
Subperiosteal space
Peripheral space
Central space
Tenon’s space
Optic nerve
Intra orbital part = — mm out of — cm
Enclosed in three ——— sheaths
At apex surrounded by ——— ,
———— pierces optic nerve 1.25 cm behind optic nerve
Optic nerve
Intra orbital part = 25 mm out of 4 cm
Enclosed in three meningeal sheaths
At apex surrounded by recti muscles ,
Central retinal artery and vein pierces optic nerve 1.25 cm behind optic nerve
Relations:
superiorly: ophthalmic artery, sup ophthal vein
Interiorly: nasociliary nerve, nerve to medial rectus
Oculomotor nerve
Divides at anterior part of ——— before entering ————
Sup division supplies :———
Inf division supplies:
And motor root relay at ciliary ganglion supplies:———
Oculomotor nerve
Divides at anterior part of cavernous sinus before Entering sup orbital fissure
Sup division Sup rectus LPS
Inf division Medial rectus Inf rectus
Inf oblique
And motor root relay at ciliary ganglion
sphincter pupillae , ciliary muscle
Trochlear nerve
Runs medially from lateral wall of ———
Above Levator palpebral sup Then supplies orbital surface of ———muscle
Trochlear nerve
Runs medially from lateral wall of cavernous sinus
Above Levator palpebral sup Then supplies orbital surface of Superior oblique
Trigeminal nerve
Three terminal branches of ophthalmic division:
——— nerve which gives off——
——— nerve; Sensory and secretomotor fibres to ———through ——— nerve
——— nerve: branches include
Trigeminal nerve
Three terminal branches of ophthalmic division:
Frontal nerve supratrochlear supraorbital
.Lacrimal nerve Sensory and secretomotor fibres to lacrimal gland tru
zygomaticotemporal nerve
Nasociliary nerve:
3. Communicating branch to sensory root of ciliary
ganglion
4. Long ciliary nerves - dilator pupillae
5. Posterior and anterior ethmoidal branches
6. Infratrochlear nerve
Orbit is made up of 7 bones : -
Made up of 7 bones :
-Ethmoid
-Frontal
-Lacrimal
-Maxillary
-Palatine
-Sphenoid
-Zygomatic
By— to —th month laying down of bone starting with ———
By 6 -7 th month laying down of bone starting with maxillary process
Embryology of orbit
During this time optic vesicles which are 170 ͦ apart are rotated ——.
During this time optic vesicles which are 170 ͦ apart are rotated anteriorly.
Gross anatomy
Dimensions
Depth ≈ —mm along medial wall
≈ — mm along lateral wall
Intraorbital width – distance between medial margins of both
orbits ≈ —mm
Extraorbital width – distance between lateral margins of both
orbits ≈ — mm
Orbital index = (height / width) ×100
>— – megasenes (orientals)
— to — – mesosenes (caucasian)
< — – microsenes (nigros)
Volume ≈ —ml
-volume of orbit : volume of eyeball = — :—
Angulations – Between lateral wall & sagital plain ≈ — ̊ - Between visual axis & orbital axis ≈ — ̊
other
- Medial wall of both orbits are —— to each
- Lateral wall of both orbits bears an angle of — ̊
Gross anatomy
Dimensions
Depth ≈ 42 mm along medial wall
≈ 50 mm along lateral wall
Intraorbital width – distance between medial margins of both
orbits ≈ 25 mm
Extraorbital width – distance between lateral margins of both
orbits ≈ 100 mm Orbital index = (height / width) ×100
>89 – megasenes (orientals) 83 – 89 – mesosenes (caucasian)
< 83 – microsenes (nigros) Volume ≈ 30ml
-volume of orbit : volume of eyeball = 4.5:1
Angulations – Between lateral wall & sagital plain ≈ 45 ̊ - Between visual axis & orbital axis ≈ 23 ̊ other - Medial wall of both orbits are parallel to each - Lateral wall of both orbits bears an angle of 90 ̊
What is the shape of the medial and inferior wall, superior, lateral
Medial- quadrangular
Inferior- triangle
Superior- triangle
Lateral- triangle
Base of orbit:
- bounded by ——— i.e. ring of compact bone which gives attachment to orbital septum.
- Divided into 4 margin:
Base of orbit:
- anterior open end of orbit.
- bounded by orbital margins i.e. ring of compact bone which gives attachment to orbital septum.
- Divided into 4 margin
Superior, lateral, inferior, medial
) Superior orbital margin:
- Formed by —— bone.
- —— 2/3 is sharp & —— 1/3 is rounded.
- At this junction lies ——— notch transmiting
———— nerves & vessels.
- About — mm medial to supraorbital notch is ——— groove
transmitting ——— nerve & artery.
) Superior orbital margin:
- Formed by frontal bone.
- Lateral 2/3 is sharp & medial 1/3 is rounded.
- At this junction lies supraorbital notch transmiting
supraorbital nerves & vessels.
- About 10 mm medial to supraorbital notch is supratrochlear groove
transmitting supratrochlear nerve & artery.
ii)Lateral orbital margin:
-Strongest/weakest?
-Formed by ———- bone & ———- bone.
ii)Lateral orbital margin:
-Strongest
-Formed by zygomatic process of frontal bone & zygomatic bone.
-It does not reach as anteriorly as medial margins.
)Inferior orbital margin:
-Formed by laterally by—— bone medially by ——— bone
- Medially it continues with ————
- — to —cm below orbital margin in line with supraorbital notch lies —— foramena transmitting ——— nerve & vessels
)Inferior orbital margin:
-Formed by laterallyzygomatic bone medially maxilla
- Medially it continues with anterior lacrimal crest.
- 4-5cm below orbital margin in line with supraorbital notch lies infraorbital foramena transmitting infraorbital nerve & vessels
Medial orbital margin:
- Formed below by ——-
-above by ——— bone
Medial orbital margin:
- Formed by below anterior lacrimal crest (maxilla) abovefrontal bone
Appertures at the base of orbit:
-.
- These fascial expansions & sup and inferior oblique muscles bound 5 ——- between them & ——— .
-These are the communications between ——— & deep portion of ———.
- Through them —— & —— passes out of orbit . Further spread in lid is prevented by ———
Appertures at the base of orbit:
- Base of orbit is closed partly by globe , extraocular muscles
& their fascial expansions.
- These fascial expansions & sup and inferior oblique muscles bound 5 orifices between them & orbital margins .
-These are the communications between orbital cavity & deep portion of eyelid.
- Through them blood & pus passes out of orbit . Further spread in lid is prevented by orbital septum.
i) superior apperture:
-———shaped
-lies between —— & upper surface
of ——
- —— from ———- lobe may
herniate through this apperture.
ii) Superomedial apperture:
-Vertically —— shape
-Lies between reflected tendon of ——— & ———
-It transmits
,
-Heniation of fat through this space is common cause of ——— in old people.
iii) Inferomedial apperture:
-Vertically —— shape
-lies between ——— & ———and———.
iv) Inferior apperture:
-——— in shape
-Bounded by ——— , arcuate expansion of ——— & ———
v) InferoLateral apperture:
-Vertically —— shape
-Lies between arcuate expansion of ——— ,——— muscle & ———
i) superior apperture:
-comma shaped
-lies between roof & upper surface
of LPS
-Fat from superomedial lobe may
herniate through this apperture.
ii) Superomedial apperture:
-Vertically oval
-Lies between reflected tendon of superior oblique & medial check ligament
-It transmitsInfratrochlear nerve , dorsal nasal artery
angular vein.
-Heniation of fat through this space is common cause of lobulated prominence in old people.
iii) Inferomedial apperture:
-Vertically oval
-lies between medial check ligament & inferior oblique and Lacrimal sac.
iv) Inferior apperture:
-Triangular
-Bounded by inferior oblique , arcuate expansion of inf oblique & floor of orbit.
v) InferoLateral apperture: -Vertically oval -Lies between arcuate expansion of inf oblique ,Inf oblique muscle & Lateral check ligament.
Apex of orbit: -
Posterior end of orbit. -
Has 2 orifices:
Optic canal
Superior orbital fissure
Apex of orbit: -Posterior end of orbit. -Has 2 orifices
i)Optic canal:
- Connects orbit to —— cranial fossa.
-Transmits —— nerve & surrounding meninges, ——— artery.
-Normal adult dimensions are attended by — to—yrs. -Length ≈ — to— mm
-Orbital end is vertically —— shaped
Centre is ——- in shape
Cranial end is horizontally —— shaped
- Optic nerve glioma & meningioma causes ———-
Apex of orbit: -Posterior end of orbit. -Has 2 orifices
i)Optic canal:
- Connects orbit to middle cranial fossa.
-Transmits Optic nerve & surrounding meninges
Ophthalmic artery.
-Normal adult dimensions are attended by 4-5 yrs. -Length ≈ 6-11mm
-Orbital end is vertically oval
Centre is circular
Cranial end is horizontally oval
- Optic nerve glioma & meningioma causes unilateral enlargement of optic canal.
Superior orbital fissure:
-———shaped
-Bounded by ——— & ——- of ——- bone
-Fissure is divided into upper middle &
lower part by ————— .
Superior orbital fissure:
-Comma shaped
-Bounded by greater & lesser wing of sphinoid.
-Fissure is divided into upper middle &
lower part by common tendinous ring .
-In optic canal dural sheath is adherant to ———-.
-In optic canal dural sheath is adherant to periorbita.
————: -thickened periorbita at orbital margins -gives attachment to orbital septum.
Arcus marginale
Lacrimal fascia: - periorbita at ——— splits into 2 layers
reunits at ———- to enclose Lacrimal sac.
Lacrimal fascia: - periorbita at post lacrimal crest splits into 2 layers reunits at anterior lacrimal crest to enclose Lacrimal sac.
————-:- Thickened periorbita at orbital apex which gives attachment to 4 recti muscles.
Tendinous ring of zinn:- Thickened periorbita at orbital apex which gives attachment to 4 recti muscles.
————-Thin connective tissue membrane lining various intraorbital structures.
Orbital fascia
——— Envelopes globe from from limbus to optic disc.
Fascia bulbi :
Fascia bulbi :
-Envelopes globe from from limbus to optic disc.
-Outer surface lies in contact with ——— posteriorly & ———anteriorly with which it merges at limbus.
-Tenon’s capsule is seperated from sclera by ————
-Lower part of fascia bulbi is thickened forming a sling on which the globe rest k/a suspensory ligament of ———-_. which extends from ———— to ———-
Orbital fascia:
-Thin connective tissue membrane lining various intraorbital structures.
-Described under following structures
i)Fascia bulbi :
-Envelopes globe from from limbus to optic disc.
-Outer surface lies in contact with orbital fat posteriorly & subconjunctival tissue anteriorly with which it merges at limbus.
-Tenon’s capsule is seperated from sclera by Episcleral space / tenon’s space .
-Lower part of fascia bulbi is thickened forming asling on which the globe rest k/a suspensory ligament of lockhood. which extends from posterior lacrimal crest to lateral orbital wall.
Surgical spaces in orbit:
1.Subperiosteal space.
2. Peripheral orbital space.
3.Central orbital space.
4. Subtenon’s space
- Subperiosteal space:
-Lies between ——— bone & ———.
- Subperiosteal space:
-Lies between orbital bone & periorbita.
Peripheral orbital space:
- Lies between - ——— at periphery
- ———- internally
- ———- anteriorlly. -Posteriorly it merges with ————
Peripheral orbital space:
- Lies between - periorbita at periphery
- extraocular muscles & their intermuscular septa internally
- orbital septum anteriorlly. -Posteriorly it merges with central space.
- ContentsPeriorbital fat SO , IO , LPS
Lacrimal , frontal , trochlear, ant & post ethmoidal nerve.
superior & inferior ophthalmic vein
Lacrimal gland & Lateral 1⁄2 of lacrimal sac.
Central orbital space:
. - Bounded by - anteriorly ———
-posteriorly by ———-
- In posterior part ,space becomes continuous with ——— space.
Central orbital space:
- k/a muscle cone / retro-orbital space / posterior space. - Bounded by - anteriorly tenon’s capsule
-posteriorly by 4 recti & intermuscular septa
- In posterior part ,space becomes continuous with peripheral space.
Subtenon’s space:
- Space around eyeball between ——— & ———
Subtenon’s space:
- Space around eyeball between sclera & tenon’s capsule
- Pus collection in this space is drained by incision on tenon’s capsule through conjunctiva.
Orbital fat & reticular tissue:
-It is divided by intermuscular septa into
- Central part
- Peripheral part:
superomedial
inferomedial
superotemporal
inferotemporal
The orbit develop around ———
Eyeball
Orbital walls are derived from ——— which expand to form ——— process and ——— process
Cranial neural crest cells
Frontonasal process
Maxillary process
Development
Lateral nasal process and maxillary process forms which walls of the orbit
Medial, inferior, lateral
The ———- forms the orbital roof
Capsule of the forebrain
Development
The bones differentiate during the during the — month and later undergo ——- or ——- ossification
3rd month
Endochondrial and membranous ossification
Endochondrial and membranous ossification,———- bone
Intramembranous ossification, ——,——,—— bones
Sphenoid
(Frontal,Maxillary ,Palatine)
Although eyeball reaches adult size around age—, the orbit undergoes considerable changes till———
3
Puberty
Periorbita is innervated by
CN 5
How many mm behind the sclerocorneal joint do the following muscles insert;
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
7.7
6.5
5.5
6.9
