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7/29/2019 13854254--Anatomy-of-orbit (1)
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Dr. Azza Zaki
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Dr. Azza Zaki
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It is pyramidal in shape, having a base, an apex & 4 walls.
Base: has 4 margins.
Apex: Optic canal.
4 Walls:Roof
1- Orbital plate of frontal b. 2-Lesser wing of sphenoid b.
Floor
1- Orbital surface of maxilla 2-Zygomatic bone
Orbital process of palatine b.
Medial wall
1- Lacrimal bone 2-Orbital plate of ethmoid b.Body ofsphenoid b.
Lateral wall
1- Zygomatic b. 2-Greater wing of sphenoid b
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The orbital cavity communicates with the:
Anterior cranial fossa via ant. and post. ethmoidalforamina
Middle cranial fossa viaoptic canal and the superior
orbital fissure Infratemporal fossa viainferior orbital fissure
Nasal cavity vianasolacrimal canal
At the meeting of the medial wall &the roof, there are:
Optic canal (optic nerve, ophthalmic artery & meninges)
Posterior ethmoidal foramen
Anterior ethmoidal foramen
There are 2 fissures related to lateral wall:
Superior orbital fissure (between lesser & greater wing of
sphenoid, pass through it: lacrimal, frontal, trochlear, superiordivision of oculomotor, nasociliary, inferior division ofoculomotor , abducent nerves & ophthalmic veins)
Inferior orbital fissure (between greater wing of sphenoid and
maxilla, passes through it: infra-orbital artery, maxillary nerve ,zygomatic nerve & emissary vein between inf. ophthalmic v. &
pterygoid plexus of veins.
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The eyeball.
The extra-ocular
m. Vessels:
Ophthalmic
artery &veins.
Nerves:
Sensory:
optic , Ophthalmic& its branches(lacrimal,frontal &nasociliary)
and zygomatic Motor: 3,4,6
Ciliary ganglion
Lacrimalapparatus
Orbital fat
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There are 4 recti ,2 obloquies & thelevator palpebrae superioris.
1-Levator palpebrae superioris
2- Superior rectus
3- Inferior rectus
4-Lateral rectus5-Medial rectus
6- Superior oblique
7-Inferior oblique
Intra-ocular: Dilator pupillae
Constrictor pupillae
Ciliary muscle
1 2
3
45
6
7
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Origin:
roof of the orbit in front of the
optic canal
Insertion :
superficial lamella: front of
superior tarsus & skin of upper
eyelid &deep lamella: upperborder of superior tarsus &
superior fornix of conjunctiva
Action:
elevation of upper eyelid andsup. fornix of conjunctiva
Nerve supply:
sup division of oculomotor n.&
smooth muscle by sympathetic
fibers from ( SCSG).
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Recti Muscles
Origin:common tendinous
ring, according to
their position (the
lateral rectus m.arises by 2 heads)
Insertion:
into the sclera, 6mm
from the limbus
(corneo-scleral
junction)
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Superior Rectus
Action:
Elevation , adduction
& intortion of eye. Nerve supply:
Superior division of
oculomotor.
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Inferior Rectus
Action:
depress, adduct &
extort the eye
Nerve supply: inferior
division of oculomotor
nerve.
Lateral rectus :
Abduct the eye &
supplied by abducent
nerveMedial rectus:
Adduct the eye &
supplied by inferior
division of oculomotor
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Superior Oblique origin:
Body of the sphenoid Insertion:
its tendon passes through thetrochlea, inserted into the sclerabehind the equator of eyeball
Action:
directs the cornea downwardsand laterally (depression.abduction and intortion)
Nerve Supply:Trochlear n.
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Inferior Oblique
Origin:
anterior part of the floor of the
orbit
Insertion: runs laterally and
upwards, inserted into the sclera
behind the equator of the eyeball
Action:
directs the cornea upwards and
laterally (depress, abduct & extortthe eye).
Nerve Supply:
inferior division of oculomotor n.
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S
OMR
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Action of the extra- ocular muscles About thevertical (X) axis the eye moves fromside-to-side Temporal displacements =Abduction Nasal displacements =Adduction
About the horizontal (Y) axis the eye movesup and down Downward displacements: Depression
Upward displacements: Elevation
About the anterior-posterior, or sagittal (Z) axis the eyerotates Temporal rotations of the superior cornea: Extorsions
Nasal rotations of the superior cornea: Intorsions
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The horizontal rod goingthrough the cornea represents
the visual axis. The vertical
rod with the arrow at the top
represents the vertical axis. As
the eye turns around the
vertical axis, the visual axis
sweeps along the horizontal .
Adduction & abduction
The rod going through thecornea represents the visual
axis. The horizontal rod with
the arrow represents the
horizontal axis. As the eye
turns around the horizontal
axis, the visual axis sweeps
along the vertical plane.
Elevation& depression
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The third plane of actionare Intortion andextortion refer to rotationaround the visual axis, asillustratedbelow. Intortion refers toa nasal rotation from the
12 o'clockposition. Extortion refersto a temporal rotationfrom the 12 o'clock
position. intortion or extortion of
the globe to keep theeyeballs level as the head
tilts.
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Anterior view
Posterior view
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Direct elevation:
Superior rectus &
inferior oblique.
Direct depression:
Inferior rectus &
superior oblique
Abduction or medialrotation:
Medial rectus, superior
and inferior recti.
Abduction or lateral
rotation:
Lateral rectus, superior
& inferior oblique
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M
L
L
M
Actions of Extra-Ocular M. Assuming That Each one Acting
Alone
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Muscle action action action testing
position
LR abduction abduction
MR adduction adduction
SR elevation intortion adduction up and out
IR depression extortion adduction down and out
IO extortion elevation abduction up and in
SO intortion depression abduction down and in
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Clinical Testing
Anatomical Action
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Innervation of the Extraocular Muscles
Medial, Inferior & Superior Rectus; InferiorOblique: Oculomotor nerve (III)
Superior Oblique:Trochlear nerve (IV)
N.B.: tendon of superior oblique passes throughthe trochlea
Lateral Rectus:Abducent nerve (VI)
N.B.: action of lateral rectus is abduction
(abducent)
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Intra-Ocular Muscles The muscles of the iris:
1- sphincter pupillae: circular in shape and are arranged aroundthe margin of the pupil.
Action: constrict the pupil in the presence of bright light.&during accomodation.
Nerve supply : parasympathetic
fibers from the oculomotor nerve(short ciliary branches of ciliary
ganglion.
2- dilator pupillae:
Radial fibers
Action:
Dilate the pupil in the presence
of light of low intensity & excessive
sympathetic stimuli as in fear.
Nerve supply : sympathetic fibers along long ciliary nerve.
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The Ciliary Muscle
Action:
Pulls the ciliary body forward.
Relax the suspensory ligament
and lens becomes more convex.
This increases the refractive
power of the lens.
Nerve supply:
Parasympathetic fibers from the
oculomotor after synaping in the
ciluiary ganglion.
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Ophthalmic artery:Branches:
Central a. of the retina
Muscular
Posterior ciliary
Anterior ciliary
Lacrimal
Supratrochlear
Supraorbital
Dorsal nasal anastomse
with facial artery.
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It is an end artery, so
thrombus of it leads to
blindness.
Branches:
Sup.&inf. Nasal
& sup.&inf. Temporal.
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Superior ophthalmic vein Inferior ophthalmic vein.
The 2 veins communicatewith facial vein anteriorly
& end posteriorly in thecavernous sinus.
The inf. Ophthalmic veincommunicate with pterygoid
plexus of veins by emissaryvein passing through the inf.orbital fissure.
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Sensory :
Optic nerve:
for vision.
Ophthalmic n.:
for general sensation.
Zygomatic n.
Motor: 3,4,6 nerves
Ciliary ganglion.
Sympathetic fibers:
from sup. Cervical
ganglion.
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Formed of axons of ganglion cells
of the retina & pierces the sclera
medial to the center of the eyeball Runs backwards and medially
and leaves the orbital cavity
through the optic canal.
Ends in the optic chiasma,
medial to the termination of ICA
The intraorbital part is sinuous,
to allow free movement of the eyeballStructures crossing optic n.
from lateral to medial: Ophthalmic artery
Nasociliary nerve
Superior ophthalmic vein
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the opthalmic artery runs below and lateral tothe optic nerve (and within its meningeal
sheath)The nerve is pierced by the central artery and
vein of the retina, 12 mm behind the eyeball
The nerve surrounded by meninges
&subarachnoid space contains CSF , So rise in CSF pressure will compress the
retinal veins & cause bulging of the optic disc(papilledema).
section of optic nerve leads to total blindnessof one eye.
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Branches:
Lacrimal:
Enters the orbit through the sup orbitalfissure (outside the common tendinous
ring)
Runs forwards and lateral, above the
lateral rectus receives a communication
from the zygomatico-temporal nerve
(which carries secretory fibers to thelacrimal gland)
Supplies the lacrimal gland
Gives palpebral branches to the lateralpart of upper eyelid
Frontal: Runs forwards beneath theroof, above the levator palpabrae
superioris &has 2 branches:
Supratrochlear & supraorbital
Nasociliary
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Nasociliary Nerve
Branches:
Communicating branch
to the ciliary ganglion
Long ciliary n. to dilatorpupillae m.
Posterior ethmoidal n.
Infratrochlear n.Anterior ethmoidal n.
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Position:
In the posterior part of the orbit on
the lateral side of the optic n.
Suspended from the nasociliary n
Roots: 1- parasympathetic:
Preganglionic parasympathetic via thenerve of the inf. oblique (oculomotor)
postganglionic short ciliary nerves
supply sphincter pupillae & ciliary
muscles.
2-Sympathetic:postganglionic from
the plexus around the int. carotid a.
3- Sensory: carry sensory fibersfrom
eyeball
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Divides into superior and
inferior divisions Both divisions enter the
orbit through the superiororbital fissure (inside thecommon tendinous ring)
The superior divisionsupplies: superior rectus
levator palpebrae superioris
The inferior divisionsupplies: Medial rectus
Inferior rectus
Inferior oblique
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The nerve to inferior oblique carries the parasympathetic
root to the ciliary ganglion
These parasympathetic fibers arise from the Edinger
Westphal nucleus in the midbrainThe postganglionic fibers supply the constrictor pupillae
and the ciliary muscle
In complete paralysis:
The eye cannot be moved downward, upward orinward.
External ( lateral) strabismus (squint).
Diplopia .
Drooping of the upper eyelid(ptosis).
dilated fixed pupil non reactive
to light.
loss of accomadation.
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Trochlear nerve
Arising fromposterior surface of the lowerlevel mid brain.
Supply superior oblique muscle.
Abd N
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Abducent Nerve Enter the eye inside the common tendinous
ring. Supply lateral rectus muscle.
Responsible for turning the eye laterally.
If cut leads to medial squint (strabismus)
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Lacrimal gland
Lacrimal ducts
Conjunctival sac
Lacrimal puncta
Lacrimal canaliculi
Lacrimal sac
Nasolacrimal duct:
open into inferior
meatus of the nose.
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Divided into orbital
&palpebralpartsby tendone of
levator palpebrae
superioris muscle.
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Lacrimal sac:It lies in the lacrimal
groove behind the medial
palpebral ligament.
Its upper end is blind
Its lower end is
continuous with the
nasolacrimal duct.
Nasolacrimal duct:
It end in the inferior
meatus of the nose.
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parasympatheticsupply:
Originates from:nucleus lacrimalis of facial nerve in pons
Then along nervus intermedius.
Preganglionicparasympathetic: Greater superficial petrosal
branch of facial nerveGreater petrosal nerve unit with deep petrosal nerve to form
nerve of pterygoid canal, which relay in pterygopalatine
ganglion then along zygomatic branch of maxillary nerve.
postganglionic parasympathetic: zygomaticotemporalbranch, then along lacrimal nerve to the gland.
Postganglionic sympathetic via deep petrosal from internal
carotid plexus.
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Orbital Fascia
Medial & lateral
check
ligaments &
suspensory
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References
Gray_s_Anatomy_Student_edition.part2.
Color_Netter_Atlas_of_Human_Anatomy.
Snell clinical anatomy for medical students 7
th
ed.
Clinically oriented anatomy 5th ed Keith Moore
http://rapidshare.com/files/78755044/Color_Netter_Atlas_of_Human_Anatomy.pdbhttp://rapidshare.com/files/78755044/Color_Netter_Atlas_of_Human_Anatomy.pdb