anatomy & physiology of eom

PRESENTATION NAME

Anatomy Physiology Extra-Ocular MusclesModerator: Dr. Arvind TenagiPresenter: Dr. Arushi Prakash

of23rd July '151&Dept. of Ophthalmology, JNMC, Belagavi

ContentsOrbital Muscles- Intrinsic ExtrinsicEmbyrologyMuscle Cone Fascia bulbiMuscle PulleyAnnulus of ZinnSpiral of TillauxOrigin & InsertionsBlood Supply Nerve SupplyCentre of RotationOcular MovementsLaws of Ocular MotilitySupranuclear Control of Eye Movements3rd, 4th, 6th Cranial Nerve Palsies

23rd July '15Dept. of Ophthalmology, JNMC, Belagavi23rd July '152

ORBITAL MUSCLESExtrinsic muscles of eyeball.Involved in movement of eyeball.

Intrinsic musclesControls shape of lens and size of pupil.Dept. of Ophthalmology, JNMC, Belagavi323rd July '15

Intrinsic Musclesiris 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, Belagavi423rd July '15

Extrinsic Muscles

Dept. of Ophthalmology, JNMC, Belagavi523rd July '15

Embryologymesodermal 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. 23rd July '15Dept. of Ophthalmology, JNMC, Belagavi6

EmbryologyAll 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 gestation23rd July '15Dept. of Ophthalmology, JNMC, Belagavi7

Microscopic AnatomyUnique because of combination of 5 different forms of muscle cellsMain 2 groups of muscle cellsFibrillenstruktur fibers similar to the muscle fibers of skeletal muscle singly innervated with large myelinated axons, motor end plates that resemble en plaque nerve endings, and many glycolytic enzymes that allow anaerobic metabolism.firing rate proportional to conducted action potentials.These characteristics allow -- rapid, all-or-none response to a single nerve stimulus, which is necessary for rapid eye movements such as saccades. Within each extraocular muscle, these relatively large fibers reside on the global side.23rd July '15Dept. of Ophthalmology, JNMC, Belagavi8

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Microscopic AnatomyFelderstruktur fibers. These fibers are unique to extraocular musclethey are multiply innervated via small axons and multiple en grappe nerve endings and have a high concentration of mitochondria for aerobic metabolism. firing rate is proportional to the nerve impulse rate, not to conducted action potentials. These characteristics allow a graded response to repetitive nerve stimuli, which is necessary for slow, precise eye movements, such as smooth pursuit, or for a tonic response necessary for gaze fixation. Within each extraocular muscle, these relatively small fibers reside on the orbital side. 23rd July '15Dept. of Ophthalmology, JNMC, Belagavi9

Microscopic AnatomyBoth groups demonstrate a high ratio of nerve fibers to eye muscle fibers compared with true skeletal muscle (approximately 1:50 to 1:100 in true skeletal muscle)Unlike the situation in skeletal muscle, individual muscle cells, both Fibrillenstruktur andFelderstruktur types, are surrounded by connective tissue. This complex of mucopolysaccharide, collagen, and elastin harbors blood supply and nerve input to the muscle23rd July '15Dept. of Ophthalmology, JNMC, Belagavi10

Dept. of Ophthalmology, JNMC, Belagavi11Muscle coneThe rectus muscle forms the muscle cone within the orbit with apex at their origin and base at their penetration of tenons 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 capsuleIntermuscular septumIntraconal fatExtraconal fat

Muscle cone

Dept. of Ophthalmology, JNMC, Belagavi12 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 insertionTenons are divided into anterior and posterior parts

Tenon capsule

10mm

Dept. of Ophthalmology, JNMC, Belagavi13Muscle 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 lengthPulley 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

Dept. of Ophthalmology, JNMC, Belagavi

Extra ocular Muscles:Origin

Superior Oblique

Levator palpebrae superioris

Medial Rectus

Lateral RectusSuperior Rectus

Inferior Rectus

Inferior Oblique14


Oval, fibrous ring at the orbital apex.

Structures passing through the annulus:1. Occulomotor nerve (superior and inferior divisions)2. Abducens Nerve3. Optic Nerve4. Nasociliary Nerve5. Ophthalmic ArteryAnnulus of Zinn15

23rd July '1516 23rd July '15 Clinical Significance Retrobulbar neuritisOrigin 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 orbitopathyMedial & 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.


SPIRAL OF TILLAUX

5.5 mm6.5 mm

6.9 mm

7.7 mm

Dept. of Ophthalmology, JNMC, Belagavi1723rdJuly '15

23rd July '1518 23rdJuly '15 Dept. of Ophthalmology, JNMC, Belagavi

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 SUPERIORISOrigin: Orbital surface of lesser wing of sphenoid bone, anterosuperior to optic canal.Insertion: Splits in two laminaSuperior lamina (voluntary) to Skin of upper eyelid & anterior surface of superior tarsal plateInferior lamina (Mullers muscle)(involuntary) to upper margin of superior tarsus (superior tarsal or mullers muscle) & superior conjunctival fornix


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NERVE SUPPLY- Upper division of occulomotor nerve.ACTION- Elevation of upper eyelid.

PtosisDrooping of upper eyelid.Complete ptosis-injury to occulomotor nerve.Partial ptosis-disruption of postganglionic sympathetic fibres from superior cervical sympathetic ganglion.


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SUPERIOR RECTUS MUSCLEOrigin-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

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Action of Superior RectusPrimary 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 midlineThus secondary action is adductionFinally, because the insertion is oblique, contraction produces torsion nasally Intorsion.

23rd July '15Dept. of Ophthalmology, JNMC, Belagavi24

INFERIOR RECTUSOrigin-inferior part of common tendon of zinnInsertion-in the sclera 6.5 mm behind sclero corneal junction.Nerve supply-inferior division occulomotor nerve.


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 RECTUSOrigin-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 RECTUSOrigin-annulus of zinn.Insertion-in the sclera 6.9mm behind sclerocorneal junction.Nerve supply-abducens nerve which enters the muscle on the medial surface.23rd July '15Dept. of Ophthalmology, JNMC, Belagavi29

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 OBLIQUELongest and thinnest intraorbital muscle, the muscle ends before the 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.


ACTIONSPrimary action-intorsion.Subsidiary actions-abduction and depression.Adducted position-depression.


INFERIOR OBLIQUEOrigin-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.


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


Origins/Insertions of Oblique muscles


Dept. of Ophthalmology, JNMC, Belagavi3623rdJuly '15 Blood supply EOM are supplied by the branches of ophthalmic artery.

Muscular branchesLacrimal braches

As the ophthalmic artery enter the muscle cone through the optic canal it braches to Lateral and Medial muscular branches

Medial muscular branchLateral muscular branch

Dept. of Ophthalmology, JNMC, Belagavi37 23rdJuly '15 Muscular artery course along with CN 3 to enter rectus muscle at the junction of posterior and middle one third.Lateral muscular branches- lateral rectussup rectusLPSSOMedial muscular branches- medial rectusinferior rectusIOLacrimal branch-LR and SR

Dept. of Ophthalmology, JNMC, Belagavi3823rdJuly '15 Anterior ciliary artery (ACA)7 in no.Branches of muscular arteriesAlong 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

ACAMuscular branchLR with single ACAClinical correlates: interruption of ACA during surgery involving more than two rectus muscle can result in anterior segment ischemia!

LPCA- long posterior ciliary artery.38

Dept. of Ophthalmology, JNMC, Belagavi3923rdJuly '15 Venous drainage of EOM The venous drainage of the extraocular muscles is via the superior and inferior orbital veins to ophthalmic veins

Anterior ciliary veinCavernous sinusInferior ophthalmic veinSuperior ophthalmic veinSuperior orbital veininferior orbital veinClinical correlates:Secondary Perimuscular infection following EOM trauma can spread infection to cavernous sinus .

Cavernous vascular disease can present as opthalmoplegia and proptosis

Dept. of Ophthalmology, JNMC, Belagavi4023rdJuly '15 Venous drainage of EOM The venous drainage of the extraocular muscles is via the superior and inferior orbital veins to ophthalmic veins

Anterior ciliary veinCavernous sinusInferior ophthalmic veinSuperior ophthalmic veinSuperior orbital veininferior orbital veinClinical correlates:Secondary Perimuscular infection following EOM trauma can spread infection to cavernous sinus .

Cavernous vascular disease can present as opthalmoplegia and proptosis

23rdJuly '15 Dept. of Ophthalmology, JNMC, BelagaviNerve Supply of Extraocular Muscles

Superior division of oculomotor:- levator palpebrae superioris, superior rectusInferior division of oculomotor:- medial rectus, inferior oblique, inferior rectusTrochlear nerve - superior obliqueAbducent nerve- lateral rectus

23rd July '1541AL3SO4LR6

23rd July '1542 23rdJuly '15 Dept. of Ophthalmology, JNMC, BelagaviStructure of EOM

Each EOM consist of 2 layers

Orbital layer which located superficially near the orbital wallGlobar 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

23rd July '1543 23rdJuly '15 Dept. of Ophthalmology, JNMC, BelagaviMicroanatomy of EOMEOM 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 SMEOM has more contractile units

This accounts for very precise and rapid movement of eye by EOM

23rd July '1544 23rdJuly '15 Dept. of Ophthalmology, JNMC, BelagaviEOM Fibers Two type 2.Multiply innervated fibers (MIFs)1.Singly innervated fibers(SIFs)

Large diameterArranged irregularlyAbundant mitochondria Multiply innervatedMany branches 1 nerve as en grappeMostly found in orbital layer of EOMAllows fatigue resistant smooth ocular movement

Small diameterRegularly arrangedFewer mitochondria Singly innervated1 nerve, 1 branch as en plaqueMostly found in globular layer of EOMAllows rapid, saccadic and precise movements

Disorders of eye MovementsStrabismus- 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.23rd July '15Dept. of Ophthalmology, JNMC, Belagavi45


Dept. of Ophthalmology, JNMC, Belagavi47Diseases where EOM are SparedEtiologyLimb Muscle PathologyDuchenne muscular dystrophyX- linked genetic mutation of dystrophin geneProgressive, Muscle wasting and weaknessBecker Muscular DystrophyX-linked genetic mutation of dystrophin gene, less severe phenotype than DuchenneProgressive, Muscle wasting and weakness, , and - sarcoglycan deficiency (limb girdle muscular dystrophy)Mutation of sarcoglycan geneProgressive, Muscle wasting and weaknessLaminin 2- congenital muscular dystrophyMutation of laminin 2 geneProgressive, Muscle wasting and weaknessAmyotropic lateral sclerosisMutations of superoxide dismutase gene; mitochondriopathyProgressive, Muscle wasting and paralysis

Dept. of Ophthalmology, JNMC, Belagavi48Diseases where EOM are primarily or preferentially involvedEtiologyEOM pathology amd /or symptomsGravess OpthalmopathyAutoimmune disease of the EOM, resulting in enlargement; presumably due to one or more shared antigens with the thyroid glandInflammatory orbitopathy, myopathyCPEO (Chronic Progressive External Ophthalmoplegia)Mitochondrial DNA deletion, mutation of DNA polymerase- gamma geneAccumulation of mutant mitochondria leads to muscle paralysisKearns- Sayre SyndromeLonger mitochondrial DNA deletions than CPEOAccumulation of mutant mitochondria leads to muscle paralysis

Dept. of Ophthalmology, JNMC, Belagavi49Diseases where EOM are primarily or preferentially involvedEtiologyEOM pathology amd /or symptomsOcular Myasthenia GravisAutoimmune disease to either the acetylcholine receptor or MuSKEOM and levator palpebrae superioris muscle weaknessMyotonic Dystrophy type 1Expansion of CTG repeat within the DMPK geneSaccadic slowing, optokinetic nystagmusMyotonic dystrophy type 2Expansion of a CCTG repeat expansion of the CNBP geneRebound NystagmusChildhood strabismusUnknown. Complex Genetic cause ?Under- or overactiveEOM with loss of binocularity and eye alignment in primary gaze

Dept. of Ophthalmology, JNMC, Belagavi50Diseases where EOM are primarily or preferentially involvedEtiologyEOM pathology amd /or symptomsCongenital NystagmusMissense mutation in FRMD7 gene; function unknown. Clinically heterogenous; multiple genes involvedConjugate, horizontal eye oscillations, in primary or eccentric gazeMiller-Fisher SyndromeAutoimmmune disease against ganglioside GQ1b/GT1aEOM paralysisCongenital cranial dysinnervation disordersSpecific gene mutation for each typeEOM weaknness or absence

23rd July '1551 23rdJuly '15 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 KINEMATICSDept. of Ophthalmology, JNMC, Belagavi

23rd July '1552 23rdJuly '15 Primary position of gazeDefined 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 Dept. of Ophthalmology, JNMC, Belagavi

23rd July '1553 23rdJuly '15 Secondary position of gaze Positions assumed by the eyes while lookingstraight up, (supraversion)straight down, (infraversion)to the right, (dextroversion)and to the left (levoversion)Dept. of Ophthalmology, JNMC, Belagavi

23rd July '1554 23rdJuly '15 Tertiary position of gazePositions assumed by the eyes when combination of vertical and horizontal movements occur. DextroelevationDextrodepressionLevoelevationlevodepression Dept. of Ophthalmology, JNMC, Belagavi

23rd July '1555Motion of an EyeTo describe eye motions we need a set of defined axes (Ficks Axes -)X axis : nasal -> temporal Y axis: anterior -> posteriorZ axis: superior -> inferior

These axes intersect at the center of rotation - a fixed point, defined as 13.5 mm behind cornea.


23rd July '1556Centre of RotationIn 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 Listings plane


23rd July '1557Dept. of Ophthalmology, JNMC, BelagaviOcular movements Ocular movement occurs around the axis of Fick 3 basic ocular movements1.Ductions 2.Version-monocular movement around the axis of FickBinocular, simultaneous,conjugate movements-(in same direction)Binocular, simultaneous, disjugate /disjunctive movement-in opposite direction3.Vergences- 1.Convergence 2.divergence

Dept. of Ophthalmology, JNMC, Belagavi5823rdJuly '15 Ductions Are tested by occluding one eye and asking the patient to follow target in each direction of gazeDuctions consist of following-

1.adduction-MR4.depression-2.abduction-LR6.Extorsion(IO)3.Elevation(SR)5.Intorsion(SO)OD

Dept. of Ophthalmology, JNMC, Belagavi5923rdJuly '15 VersionTested 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.drepression8.elevation1.Primary position4.Dextrodrepression(ODIR+OSSO)

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Dept. of Ophthalmology, JNMC, BelagaviMUSCLES CAUSING MONOCULAR MOVEMETS

Primary muscle action is the main and most powerful direction in which the eye moves when the muscle is contractedSecondary muscle action is the second direction in which the eye moves when that muscle is contracted, but is not the main or most important actionTertiary muscle action is the least powerful direction in which the eye moves as a result of contraction of the muscle

With the eye in primary position,the horizontal rectus muscles arepurely horizontal movers aroundthe z-axis (the vertical axis), andthey have a primary action only.The vertical rectus muscles have adirection of pull that is mostlyvertical as their primary action,but the angle of pull from originto insertion is inclined 23 to thevisual axis, giving rise which is definedas any rotation of the vertical cornealmeridians.

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23rd July '1561Dept. of Ophthalmology, JNMC, Belagavi

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.


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

6323rd July '1563MUSCLE PRIMARY ACTIONSECONDARY ACTIONTERTIARY ACTION MR ADDUCTION __________ ____________ LRABDUCTION __________ ____________ SR ELEVATIONINTORSION ADDUCTION IR DEPRESSION EXTORSION ADDUCTION SO INTORSION DEPRESSION ABDUCTION IO EXTORSION ELEVATIONABDUCTION


Superior ObliqueInferior ObliqueSuperior rectusInferior rectusMedial rectusLateral rectus

23rd July '1565Dept. of Ophthalmology, JNMC, BelagaviLaws of ocular motility

AgonistAny particular EOM producing specific ocular movement

Synergists Muscles of the same eye that move the eye in the same direction

AgonistAny particular EOM producing specific ocular movementEx. Right LR for right eye abduction

Synergists Muscles of the same eye that move the eye in the same directionEx. Right SR and right IO for right eye elevation

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23rd July '1566Dept. of Ophthalmology, JNMC, BelagaviAntagonists 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

Antagonists A pair of muscles in the same eye that move the eye in opposite directionsEx. right LR and right MR

Yoke muscles ( contralateral synergists)Pair of muscles, one in each eye , that produce conjugate ocular movements Ex. right LR and left MR in dextroversion

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23rd July '1567Dept. of Ophthalmology, JNMC, BelagaviAgonist-Antagonist Pairs (in the Same Eye)Medial rectuslateral rectusSuperior rectusinferior rectusSuperior obliqueinferior obliquePaired Agonists (in Separate Eyes)Left medial rectusright lateral rectusLeft lateral rectusright medial rectusLeft superior rectusright inferior obliqueLeft inferior rectusright superior obliqueLeft superior obliqueright inferior rectusLeft inferior obliqueright superior rectus


Listings LawAll 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


69An 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 HERINGS LAW OF EQUAL INNERVATION

23rd July '15Dept. of Ophthalmology, JNMC, Belagavi70States 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

SHERRINGTONS LAW OF RECIPROCAL INNERVATION

23rd July '15Dept. of Ophthalmology, JNMC, Belagavi71Applied 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 SquintLateral Squint and Ptosis -Dropping of Eyelid.23rd July '15Dept. of Ophthalmology, JNMC, Belagavi71

23rd July '15Dept. of Ophthalmology, JNMC, Belagavi72Supranuclear Control of Eye Movements

23rd July '1573Dept. of Ophthalmology, JNMC, BelagaviFunctional Classification of Eye Movement SystemsDirect the fovea to an object of interest: Saccades Smooth pursuit Vergence Hold images steady on the retina: Fixation Vestibulo-ocular reflex (VOR) Optokinetic nystagmus

23rd July '1574Dept. of Ophthalmology, JNMC, BelagaviSaccadesRapid 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 SaccadesGaze Centerscueflash.com/decks/CONTROL_OF_EYE_MOVEMENTS_-_57

HorizontalParamedian pontine reticular formation (PPRF)VerticalRostral interstitial nucleus (rostral iMLF)

PPRF and MLF combined lesions on the same side give rise to the one-and-a-half syndrome which is characterized by a combination of ipsilateral gaze palsy and INO so that the only residual movement is abduction of the contralateral eye which also exhibits ataxic nystagmus

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23rd July '1576Dept. of Ophthalmology, JNMC, BelagaviPursuitFollowing 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

23rd July '1577Dept. of Ophthalmology, JNMC, BelagaviVergence Eye MovementsMaintain fusion of images when targets move towards or away from the eyes. Velocity: 20 / sec. Control center lies in the midbrain

23rd July '1578Dept. of Ophthalmology, JNMC, BelagaviFixationPurpose- Maintaing the image of the object of regard on the foveaSupplementary 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)

23rd July '1579Dept. of Ophthalmology, JNMC, BelagaviVestibulo 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

23rd July '1580Dept. of Ophthalmology, JNMC, BelagaviOptokinetic 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 PalsyRight 3rd Nerve palsy is charactarized by the followingWeakness 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 '15Dept. of Ophthalmology, JNMC, Belagavi8123rdJuly '15

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




Left 4th nerve palsy23rd July '15Dept. of Ophthalmology, JNMC, Belagavi8523rdJuly '15 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


.23rd July '15Dept. of Ophthalmology, JNMC, Belagavi8723rdJuly '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




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

Long-standing left 6th nerve palsy Dept. of Ophthalmology, JNMC, BelagaviLeft 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.

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Differential DiagnosisMyasthenia 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.


Differential DiagnosisOrbital 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.23rd July '15Dept. of Ophthalmology, JNMC, Belagavi9423rdJuly '15

95Wolffs Anatomy of Eye -8th editionParsons Disease of the Eye-21st edAdlers Physiology of the Eye- 11th edJack.J.Kanski Brad Bowling Clinical Ophthalmology -7th edYanoff & Duker Ophthalmology- 3rd edhttp://www.downstate.edu/ophthalmology/pdf/Grand-Rounds-Arun-Joseph.pdfhttp://rmsolutions.net/rmfiles/Retina2010/014002.pdfhttp://91.146.107.207/~wwwacnr/wp-content/uploads /2012/09/12-ACNRJA12_Ophthalmology7.pdf

Thankyou 23rd July '15Dept. of Ophthalmology, JNMC, Belagavi96

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