Anatomy & physiology of eom

Anatomy Physiology
Extra-Ocular Muscles
Moderator: Dr. Arvind Tenagi
Presenter: Dr. Arushi Prakash
of
23rd July '15
1
&
Dept. of Ophthalmology, JNMC, Belagavi

Contents
• Orbital Muscles-
Intrinsic
Extrinsic
• Embyrology
• Muscle Cone
• Fascia bulbi
• Muscle Pulley
• Annulus of Zinn
• Spiral of Tillaux
• Origin & Insertions
• Blood Supply
• Nerve Supply
• Centre of Rotation
• Ocular Movements
• Laws of Ocular Motility
• Supranuclear Control of Eye Movements
• 3rd, 4th, 6th Cranial Nerve Palsies
23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi
23rd July '15
2

ORBITAL MUSCLES
Extrinsic muscles of eyeball.
• Involved in movement of eyeball.
Intrinsic muscles
• Controls shape of lens and size of pupil.
Dept. of Ophthalmology, JNMC, Belagavi 3
23rd July '15

Intrinsic Muscles
• iris sphincter,
• radial pupilodilator muscles
• ciliary muscle
• Controlled by autonomic nervous system, work in
response to amount of light, closeness of an object
(for focusing), etc
• serve to focus the eye and
control the amount of light
entering it Dept. of Ophthalmology, JNMC, Belagavi 4
23rd July '15

Extrinsic Muscles
Involuntary Muscles
Superior Tarsal Muscle
Inferior Tarsal Muscle
Orbitalis
Voluntary Muscles
Levator Palpebrae Superioris
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus
Superior Oblique
Inferior Rectus
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Embryology
• mesodermal origin,
• Perimuscular Connective tissues from neural crest
• development beginning at 3– weeks of gestation.
• muscles originate from three separate foci of primordial
cells-
 one for the muscles innervated by the oculomotor nerve,
 one for the superior oblique muscle,
 one for the lateral rectus muscle.
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Embryology
• All EOM develop in situ;
• receive input from their respective cranial nerves as early as
1 month of gestation.
• All of the extraocular muscle and their surrounding tissues
are present and in their final anatomical positions by 6
months of gestation, merely enlarging throughout the
remainder of gestation
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Muscle cone
 The rectus muscle forms the muscle
cone within the orbit with apex at their
origin and base at their penetration of
tenon’s capsule.
 Each muscle is surrounded by fibrous
capsule which are attached by thin
continuous membrane called
intermuscular septum
 Intermuscular septum divides orbital
fat pad into extraconal fat and
intraconal fat which help to maintain
cushioning effects.
 Intermuscular septum fuses with tenon
3mm from the limbus
Fibrous capsule
Intermuscular
septum
Intraconal fat
Extraconal fat
Muscle cone

The Fascia Bulbi The tenon capsule/fascia bulbi is an envelope
of elastic fibrous connective tissue
 Form protective covering at site of attachment
of EOM
 Tenon capsule fuses with optic nerve sheath
posteriorly and anteriorly with intermascular
septum, 3 mm posterior to the limbus.
 EOM penetrates the tenon capsule 10 mm
posterior to their insertion
 Tenons are divided into anterior and posterior
parts
Tenon capsule
10mm

Muscle pulley
 As the EOM penetrates the tenon
capsule the connective tissue forms the
sleeves around the muscles creating
muscle pulleys.
 Discrete rings of dense collagen tissue
encircling EOM & are about 2mm
length
 Pulley redirects the muscle and acts as
functional origin it also prevents
displacement of muscle during
movement
 Because of pulley mechanism muscle
are inflect at the insertion forming
angle with the orbital axis. muscle
pulley
Pulley
Angle

Extra ocular Muscles:Origin
Superior ObliqueLevator palpebrae superioris
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior Rectus
Inferior Oblique
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Oval, fibrous ring at the
orbital apex.
Structures passing
through the annulus:
1. Occulomotor nerve
(superior and inferior
divisions)
2. Abducens Nerve
3. Optic Nerve
4. Nasociliary Nerve
5. Ophthalmic Artery
Annulus of Zinn
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Clinical Significance
 Retrobulbar neuritis
○ Origin of SUPERIOR AND MEDIAL RECTUS are closely attached to the dural
sheath of the optic nerve, which leads to pain during upward & inward
movements of the globe.
 Thyroid orbitopathy
○ Medial & Inf.rectus thicken. especially near the orbital apex - compression of
the optic nerve as it enters the optic canal adjacent to the body of the
sphenoid bone.
 Ophthalmoplegia
○ Proptosis occur due to muscle laxity.Dept. of Ophthalmology, JNMC, Belagavi

SPIRAL OF TILLAUX
5.5 mm
6.5 mm
6.9 mm
7.7 mm
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 Medial rectus inserts closest to the limbus and is therefore
susceptible to injury during ant. segment surgery.
 Inadvertent removal of the MR is a well known complication
of Pterygium removal
 The Scleral thickness behind the rectus insertion is the
thinnest, being only 0.3 mm thick -> chances of scleral
perforation while suturing
Clinical Significance

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LEVATOR PALPEBRAE SUPERIORIS
 Origin: Orbital surface of lesser
wing of sphenoid bone,
anterosuperior to optic canal.
 Insertion: Splits in two lamina
 Superior lamina (voluntary) to
Skin of upper eyelid & anterior
surface of superior tarsal plate
 Inferior lamina (Muller’s
muscle)(involuntary) to upper
margin of superior tarsus
(superior tarsal or muller’s
muscle) & superior conjunctival
fornix Dept. of Ophthalmology, JNMC, Belagavi

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• NERVE SUPPLY-
Upper division of occulomotor nerve.
• ACTION-
Elevation of upper eyelid.
• Ptosis
Drooping of upper eyelid.
• Complete ptosis-injury to occulomotor nerve.
• Partial ptosis-disruption of postganglionic
sympathetic fibres from superior cervical
sympathetic ganglion.

23rd July '15
22Dept. of Ophthalmology, JNMC, Belagavi

SUPERIOR RECTUS MUSCLE
• Origin-Superior part of
common tendon of zinn.
• Insertion-inserted into
sclera by flat tendinous
insertion(10mm
broad)about 7.7 mm
behind sclero-corneal
junction.
• Nerve supply-superior
division of occulomotor
nerve.
Dept. of Ophthalmology, JNMC, Belagavi23rd July '15 23

Action of Superior Rectus
• Primary action is elevation . . But since the
insertion on the globe is lateral as well as
superior, contraction will produce rotation about
the vertical axis toward midline
• Thus secondary action is adduction
• Finally, because the insertion is
oblique, contraction produces
torsion nasally Intorsion.
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INFERIOR RECTUS
• Origin-inferior part of
common tendon of zinn
• Insertion-in the sclera 6.5
mm behind sclero corneal
junction.
• Nerve supply-inferior
division occulomotor
nerve.
23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi 25

• Fascial attachments below attached to inferior
lid coordinate depression and lid opening.
• Fascia below Inf. Rectus and Inf. Oblique
contribute to the suspensory ligament of
lockwood.
• ACTIONS-
Primary depressor.
Subsidiary actions are
adduction and extorsion.

MEDIAL RECTUS
• Origin-annulus of zinn
and from optic nerve
sheath.
• Insertion-in sclera
5.5mm behind
sclero-corneal junction.
• Nerve supply-lower
division of occulomotor nerve.
• Fascial expansion from muscle sheath forms the
medial check ligament and attach to medial wall of
orbit.

• Innervation is via cranial nerve III, the
oculomotor nerve, and the specific branch runs
along the inside of the muscle cone, on the
lateral surface.
• The superior oblique, ophthalmic artery and
nasociliary nerve all lie above the medial rectus.
• ACTION-
Primary adductor of
the eye.

LATERAL RECTUS
• Origin-annulus of zinn.
• Insertion-in the sclera 6.9mm behind sclerocorneal
junction.
• Nerve supply-abducens nerve which enters the muscle
on the medial surface.

• The lacrimal artery and nerve run along the superior
border.
• The abducens nerve, ophthalmic artery and ciliary
ganglion lie medial to the lateral rectus and between it
and the optic nerve.
• ACTION-
Primary abductor of eye.

SUPERIOR OBLIQUE
• Longest and thinnest intraorbital
muscle, the muscle ends before t
he trochlea, tendon is 2.5 cm,
smooth movement through
trochlea.
• Origin-body of sphenoid above and medial to optic
canal.Passes along superomedial part of orbit and ends in
a tendon.
• Insertion-Posterosuperior quadrant of sclera behind
equator of eyeball.
• Nerve supply-trochlear nerve entering it approximately
one third of the distance from the origin to the trochlea.

ACTIONS
 Primary action-intorsion.
 Subsidiary actions-abduction and depression.
 Adducted position-depression.

INFERIOR OBLIQUE
• Origin-Anteromedial part of orbital floor lateral to
nasolacrimal groove.
• Insertion-posteroinferior surface of globe near the
macula.
• Nerve supply-inferior division of occulomotor nerve
enters the muscle laterally at the junction of the inferior
oblique and inferior rectus muscles.

ACTIONS
• Primary action-extorsion.
• Subsidiary actions-elevations and abduction.
• Causes elevation only in adducted position of
eyeball.

Origins/Insertions of Oblique
muscles

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Blood supply
EOM are supplied by the
branches of ophthalmic artery.
1. Muscular branches
2. Lacrimal braches
As the ophthalmic artery enter
the muscle cone through the
optic canal it braches to Lateral
and Medial muscular branches
Medial muscular
branch
Lateral muscular
branch

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• Muscular artery course along
with CN 3 to enter rectus muscle
at the junction of posterior and
middle one third.
• Lateral muscular branches-
a. lateral rectus
b. sup rectus
c. LPS
d. SO
• Medial muscular branches-
a. medial rectus
b. inferior rectus
c. IO
• Lacrimal branch-LR and SR

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Anterior ciliary artery (ACA)
• 7 in no.
• Branches of muscular arteries
• Along tendons of muscles and pierce
sclera 4 mm from the limbus and enter
eyeball
• Join the LPCA to form the major
arterial circle of iris.
• Supplies -- Cilliary body and iris.
• ACA runs in pair in each rectus muscle
except LR which has only one
ACA
Muscular
branch
LR with single
ACA
Clinical correlates:
interruption of ACA during surgery
involving more than two rectus muscle
can result in anterior segment
ischemia!

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Venous drainage of EOM
• The venous drainage of the extraocular muscles is via the
superior and inferior orbital veins to ophthalmic veins
Anterior ciliary
vein
Cavernous
sinus
Inferior
ophthalmic
vein
Superior
ophthalmic
vein
Superior
orbital vein
inferior
orbital vein
Clinical correlates:
Secondary Perimuscular
infection following EOM
trauma can spread
infection to cavernous
sinus .
Cavernous vascular
disease can present as
opthalmoplegia and
proptosis

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Nerve Supply of Extraocular
Muscles
Superior division of oculomotor:- levator palpebrae superioris, superior rectus
Inferior division of oculomotor:- medial rectus, inferior oblique, inferior rectu
Trochlear nerve - superior oblique
Abducent nerve - lateral rectus
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AL3SO4LR

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Structure of EOM
Each EOM consist of 2 layers –
1. Orbital layer which located
superficially near the orbital wall
2. Globar layer which is located more
deeper
• Fibers of Global layer become
contiguous with tendon to insert on the
globe ; orbital layer is inserted on
muscle pulley

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Microanatomy of EOM
• EOM are striated muscles with bundles
of muscle fibers(functional units) which
is made up of actin and myocin
filaments
• Compared to skeletal muscle(SM)EOM
fibers are small and numerous with
abundant nucleus which are highly
innervated- ratio of nerve to muscle
fiber of 1:3-1:5 compared 1: 50-1:125 of
SM
• EOM has more contractile units
• This accounts for very precise and rapid
movement of eye by EOM

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EOM Fibers
Two type
2.Multiply innervated fibers (MIFs)1.Singly innervated fibers(SIFs)
• Large diameter
• Arranged irregularly
• Abundant mitochondria
Multiply innervated
Many branches 1 nerve as en
grappe
Mostly found in orbital layer of
EOM
Allows fatigue resistant smooth
ocular movement
• Small diameter
• Regularly arranged
• Fewer mitochondria
 Singly innervated
1 nerve, 1 branch as en plaque
Mostly found in globular layer
of EOM
Allows rapid, saccadic and
precise movements

Disorders of eye Movements
• Strabismus- misalignment of the eyes such that disparate images
reach corresponding parts of each retina, disruption binocuular
vision
• Nystagmus- bilateral, involuntary, and conjugate oscillation of
the eyes
• Congenital Cranial Dysinnnervation Disorders (CCDD)- rare, non-
progressive inherited strabismic disorders characterized by
congenital fibrosis of one or more of the EOM resulting in a static
eye position or directional impairment.
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Diseases where EOM
are Spared
Etiology Limb Muscle Pathology
Duchenne muscular
dystrophy
X- linked genetic
mutation of dystrophin
gene
Progressive, Muscle
wasting and weakness
Becker Muscular
Dystrophy
X-linked genetic
mutation of dystrophin
gene, less severe
phenotype than
Duchenne
Progressive, Muscle
α, γ, and δ- sarcoglycan
deficiency (limb girdle
muscular dystrophy)
Mutation of sarcoglycan
gene
Progressive, Muscle
Laminin α2- congenital
muscular dystrophy
Mutation of laminin α2
gene
Progressive, Muscle
Amyotropic lateral
sclerosis
Mutations of superoxide
dismutase gene;
mitochondriopathy
Progressive, Muscle
wasting and paralysis

Diseases where EOM
are primarily or
preferentially involved
Etiology EOM pathology amd /or
symptoms
Graves’s Opthalmopathy Autoimmune disease of
the EOM, resulting in
enlargement;
presumably due to one
or more shared antigens
with the thyroid gland
Inflammatory
orbitopathy, myopathy
CPEO (Chronic
Progressive External
Ophthalmoplegia)
Mitochondrial DNA
deletion, mutation of
DNA polymerase-
gamma gene
Accumulation of mutant
mitochondria leads to
muscle paralysis
Kearns- Sayre Syndrome Longer mitochondrial
DNA deletions than
CPEO
Accumulation of mutant
mitochondria leads to
muscle paralysis

Diseases where EOM
are primarily or
symptoms
Ocular Myasthenia
Gravis
Autoimmune disease to
either the acetylcholine
receptor or MuSK
EOM and levator
palpebrae superioris
muscle weakness
Myotonic Dystrophy type
1
Expansion of CTG repeat
within the DMPK gene
Saccadic slowing,
optokinetic nystagmus
Myotonic dystrophy type
2
Expansion of a CCTG
repeat expansion of the
CNBP gene
Rebound Nystagmus
Childhood strabismus Unknown. Complex
Genetic cause ?
Under- or overactive
EOM with loss of
binocularity and eye
alignment in primary
gaze

Diseases where EOM
are primarily or
symptoms
Congenital Nystagmus Missense mutation in
FRMD7 gene; function
unknown. Clinically
heterogenous; multiple
genes involved
Conjugate, horizontal
eye oscillations, in
primary or eccentric
gaze
Miller-Fisher Syndrome Autoimmmune disease
against ganglioside
GQ1b/GT1a
EOM paralysis
Congenital cranial
dysinnervation disorders
Specific gene mutation
for each type
EOM weaknness or
absence

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• The primary position of the eye is that position from
which all other ocular movements are initiated
• A total of nine positions of gaze have been described.
One primary
4 secondary
4 tertiary positions
BASIC KINEMATICS

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Primary position of gaze
• Defined by Scobee
Position of the eyes in binocular vision when,
with the head erect, the object of regard is at
infinity and lies at the intersection of the
sagittal plane of the head and a horizontal
plane passing through the centres of rotation
of the two eyeballs

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Secondary position of gaze
• Positions assumed by the eyes while looking
• straight up, (supraversion)
• straight down, (infraversion)
• to the right, (dextroversion)
• and to the left (levoversion)

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Tertiary position of gaze
• Positions assumed by the eyes when
combination of vertical and horizontal
movements occur.
• Dextroelevation
• Dextrodepression
• Levoelevation
• levodepression

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Motion of an Eye
• To describe eye motions we
need a set of defined axes
(Fick’s Axes -)
• X axis : nasal -> temporal
• Y axis: anterior -> posterior
• Z axis: superior -> inferior
• These axes intersect at the center of rotation - a fixed
point, defined as 13.5 mm behind cornea.

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Centre of Rotation
In primary position - lies 13.5 mm
behind the apex of cornea.
In big myopic eyes, the centre of
rotation is a bit farther posterior and
in small hyperopic eyes it is a bit
anterior to this ideal position
 The X and Z axis lie in the same plane.
 This plane passing through the centre
of rotation of the eye and containing
the X and Z axes is called Listing’s plane

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Ocular movements
 Ocular movement occurs around the axis of Fick
3 basic ocular movements
1.Ductions –
2.Version-
monocular movement
around the axis of Fick
Binocular, simultaneous,
conjugate movements-
(in same direction)
Binocular, simultaneous,
disjugate /disjunctive
movement-in opposite
direction
3.Vergences-
1.Convergence
2.divergence

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Ductions
 Are tested by occluding one eye and asking the patient to
follow target in each direction of gaze
 Ductions consist of following-
1.adduction-MR
4.depression-
2.abduction-LR
6.Extorsion
(IO)
3.Elevation
(SR) 5.Intorsion
(SO)
OD

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Version
 Tested with both eye open and asking patient to follow a
target in each direction of gaze.
 Following are the various gaze of versions-9 cardinal gaze
3.Dextroelevation
(ODSR+OSIO)
2.Destroversion
ODLR+OSMR)
5.Laevoversion
(OSLR+ODMR)
6.Laevoelevation
(OSSR+ODIO)
7.Laevodrepression
(OSIR+ODSO)9.drepression
8.elevation
1.Primary position
4.Dextrodrepression
(ODIR+OSSO)

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MUSCLES CAUSING MONOCULAR MOVEMETS
• Primary muscle action is the main and most powerful
direction in which the eye moves when the muscle is
contracted
• Secondary muscle action is the second direction in
which the eye moves when that muscle is contracted, but
is not the main or most important action
• Tertiary muscle action is the least powerful direction in
which the eye moves as a result of contraction of the
muscle

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• When the globe is abducted to 23°, the visual and orbital axis
coincide. In this position superior rectus acts as a pure
elevator.
• If the globe were adducted to 67° the angle between the visual
and orbital axis would be 90° In this position SR would act as
a pure intorter.

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• When the globe is adducted to 51 ͦ, the visual axis coincides with
the line of pull of the muscle, the SO acts as a depressor
• When the globe is abducted to 39 ͦ, the visual axis and the SO
make an angle of 90 ͦ, the SO causes only intorsion

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MUSCLE PRIMARY
ACTION
SECONDARY
ACTION
TERTIARY
ACTION
MR ADDUCTION __________ ____________
LR ABDUCTION __________ ____________
SR ELEVATION INTORSION ADDUCTION
IR DEPRESSION EXTORSION ADDUCTION
SO INTORSION DEPRESSION ABDUCTION
IO EXTORSION ELEVATION ABDUCTION

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Superior Oblique
Inferior Oblique
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus

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Laws of ocular motility
• Agonist
– Any particular EOM producing specific ocular
movement
• Synergists
– Muscles of the same eye that move the eye in the
same direction

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• Antagonists
– A pair of muscles in the same eye that move the eye
in opposite directions
• Yoke muscles ( contralateral synergists)
– Pair of muscles, one in each eye , that produce
conjugate ocular movements

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• Agonist-Antagonist Pairs (in the Same Eye)
• Medial rectus–lateral rectus
• Superior rectus–inferior rectus
• Superior oblique–inferior oblique
• Paired Agonists (in Separate Eyes)
• Left medial rectus–right lateral rectus
• Left lateral rectus–right medial rectus
• Left superior rectus–right inferior oblique
• Left inferior rectus–right superior oblique
• Left superior oblique–right inferior rectus
• Left inferior oblique–right superior rectus

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Listing’s Law
• All achieved eye orientations
can be reached by starting
from one specific "primary"
reference orientation and then
rotating about an axis that lies
within the plane orthogonal to
the primary orientation's gaze
direction (line of sight / visual
axis).
• This plane is called Listing's
plane.
• According to Listing
cycloversion is 0°

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• An equal and simultaneous innervation flows from
the brain to a pair of yoke muscles which contracts
simultaneously in different binocular movements
• Ex. Right LR and Left MR during dextroversion
• Applies to all normal eye movements
HERING’S LAW OF EQUAL INNERVATION

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• States that increased innervation to a contracting
agonist muscle is accompanied by reciprocal
inhibition of its antagonist
• Ex. During detroversion there is increased
innervation to right LR and left MR accompanied by
decreased flow to right MR and left LR
SHERRINGTON’S LAW OF RECIPROCAL
INNERVATION

71
Applied Anatomy
• Abnormal deviation of eyeball is known as Squint
(Strabismus).
• Paralysis of Lateral rectus due to damage to
Abducent nerve leads to Medial Squint.
• Damage to Occulomotor nerve leads to paralysis
of all muscles of eye except Superior oblique and
lateral rectus leading to Lateral Squint and
Ptosis-Dropping of Eyelid.
• Damage to Trochlear nerve cause paralysis of
superior oblique muscle causing diplopia while
looking downwards.
Medial Squint
Lateral Squint and Ptosis
-Dropping of Eyelid.
23rd July '15Dept. of Ophthalmology, JNMC, Belagavi 71

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Supranuclear Control of Eye
Movements

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Functional Classification of Eye Movement
Systems
Direct the fovea to an object of interest:
• Saccades
• Smooth pursuit
• Vergence
Hold images steady on the retina:
• Fixation
• Vestibulo-ocular reflex (VOR)
• Optokinetic nystagmus

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Saccades
• Rapid eye movements to direct the
fovea to a target whose image is
falling peripherally on the retina or a
voluntary command eye movement.
• Velocity: 300 – 700° / sec.
• Initiation by: Frontal eye field or
pariteal eye field

Neural Control of Saccades
Gaze Centers
cueflash.com/decks/CONTROL_OF_EYE_MOVEMENTS_-_57
• Horizontal
- Paramedian pontine
reticular formation
(PPRF)
• Vertical
- Rostral interstitial
nucleus (rostral iMLF)

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Pursuit
• Following movements with the purpose of
maintaing the image of a slowly moving samll
object on the fovea.
• Velocity: up to 100° / sec.
• Initiation by: Temporo-occipital junctiion

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Vergence Eye Movements
• Maintain fusion of images when
targets move towards or
away from the eyes.
• Velocity: 20° / sec.
• Control center lies in the midbrain

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Fixation
• Purpose- Maintaing the image of the
object of regard on the fovea
• Supplementary eye fields maintain
fixation with the eyes in specific orbital
locations and also inhibits visually
evoked saccadic reflexes.
• Frontal eye field is involved in changing
fixation (disengaging)

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Vestibulo Vestibulo-ocular Reflex (VOR) ocular
Reflex (VOR)
• Maintains fixation during
brief head movements.
• Input from vestibular nuclei travels through
MLF to ocular motor nuclei.
• Initiation by: Otolith receptors and
semicircular canalas. Second order neuronn
are in the vestibular nuclei

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Optokinetic Nystagmus (OKN)
• Maintains fixation during target
movement or sustained head
movements.
• Fast & slow phases.
• Fast phase is controlled by
contralateral frontal eye field &
slow phase by ipsilateral
parieto-occipito-temporal area.

3rd Nerve Palsy
• Right 3rd
Nerve palsy is charactarized by the following
• Weakness of the levator causing profound ptosis, due to
which there is often no diplopia.
• Unopposed action of the lateral rectus causing the eye to be
abducted in the primary position. The intact superior oblique
muscle causes intorsion of the eye at rest which increases on
attempted downgaze.
• Normal abduction because the lateral rectus is intact.
• Weakness of the medial rectus limiting adduction.23rd July '15 Dept. of Ophthalmology, JNMC, Belagavi
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• Weakness of superior rectus and inferior oblique, limiting
elevation.
• Weakness of inferior rectus limiting depression.
• Parasympathetic palsy causing a dilated pupil associated with
defective accommodation.
• Partial involvement will produce milder degrees of
ophthalmoplegia
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Left 4th nerve palsy
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• Characterized by:
• Left hypertropia (‘left-over-right’) in the primary position.
• Increase in left hypertropia on right gaze due to left inferior
oblique overaction.
• Limitation of left depression on adduction.
Normal left abduction.
Normal left depression.
• Normal left elevation

.
87
23rdJuly '15
• Abnormal head posture avoids diplopia which is vertical,
torsional and worse on looking down.
• To intort the eye (alleviate excyclotorsion) there is
contralateral head tilt to the right.
• To alleviate the inability to depress the eye is adduction, the
face is turned to the right and the chin is slightly depressed.
• The left eye cannot look down and to the right or intort – the
head therefore does this and thus compensates

89
23rdJuly '15

• Acute left 6th
nerve palsy
• Left esotropia in
the primary
position.
• Marked
limitation of left
abduction.
Acute 6th
nerve palsy
23rdJuly '15
90

Long-standing left 6th nerve palsy
• Left esotropia in the primary
position due to unopposed
action of the left medial rectus.
• The deviation is
characteristically worse for a
distant target and less or absent
for near fixation.
Marked limitation of left
abduction due to weakness of
the left lateral rectus.
• Normal left adduction.
23rdJuly '15
91

92
23rdJuly '15

Differential Diagnosis
• Myasthenia gravis can mimic virtually any ocular motility defect.
Distinguishing features include variability of diplopia and other signs such
as lid fatigue and the Cogan twitch sign.
• Restrictive thyroid myopathy involving the medial rectus may give rise to
limitation of abduction. Associated features include orbital and eyelid
signs and a positive forced duction.
• Medial orbital wall blowout fracture with entrapment of the medial
rectus, giving rise to limitation of abduction.
93
23rdJuly '15

Differential Diagnosis
• Orbital myositis involving the lateral rectus is characterized by weakness
of abduction and pain when this is attempted.
• Duane syndrome is a congenital condition characterized by defective
abduction and narrowing of the palpebral fissure on adduction.
• Convergence spasm typically affects young adults and is characterized by
convergence with miosis and increased accommodation.
• Divergence paralysis is a rare condition which may be difficult to
distinguish from unilateral or bilateral 6th nerve palsy. However, unlike 6th
nerve palsy the esotropia may remain the same or diminish on lateral
gaze.
94
23rdJuly '15

95
• Wolff’s Anatomy of Eye -8th edition
• Parson’s Disease of the Eye-21st ed
• Adler’s Physiology of the Eye- 11th ed
• Jack.J.Kanski Brad Bowling Clinical
Ophthalmology -7th ed
• Yanoff & Duker Ophthalmology- 3rd ed
• http://www.downstate.edu/ophthalmology/p
df/Grand-Rounds-Arun-Joseph.pdf
• http://rmsolutions.net/rmfiles/Retina2010/0
14002.pdf
• http://91.146.107.207/~wwwacnr/wp-

Thankyou


Anatomy & physiology of eom

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