Eye Muscles and Ocular Movements, Laws of ocular Motility

Dr. Abdikariim Mohamoud MoahmedDr. Abdikariim Mohamoud MoahmedUniversity Of Hargeisa University Of Hargeisa Hargeisa. SomalilandHargeisa. Somaliland

OutlineOutline Extraocularmusles(EOM):Extraocularmusles(EOM): Action of the RECTI.Action of the RECTI. Types of Eye MovementsTypes of Eye Movements UniocularUniocular BionocularBionocular Synergists, Antagonists, Contralateral antagonist, Yoke muscleSynergists, Antagonists, Contralateral antagonist, Yoke muscle Diagnostic positions of gazeDiagnostic positions of gaze cardinal positionscardinal positions Laws of ocular motilityLaws of ocular motility Hering’s lawHering’s law Sherrington law of reciprocal innervationSherrington law of reciprocal innervation

Extraocularmusles(EOM)Extraocularmusles(EOM)

They are They are sixsix in number in numberFour recti:Four recti: Superior rectusSuperior rectus Inferior rectusInferior rectus Medial rectusMedial rectus Lateral rectusLateral rectusTwo oblique musclesTwo oblique muscles:-:- Superior obliqueSuperior oblique Inferior obliqueInferior oblique

Action of the RECTIAction of the RECTIMedial & lateral recti lie in the same horizontal

plane

Around a vertical axis

Medial rectus - adduction Lateral rectus - abduction

Action of the RECTIAction of the RECTISuperior rectusSuperior rectusAround the transverse axis – rotates the eyeball Around the transverse axis – rotates the eyeball upwards upwards – – Elevation (Elevation (PRIMARY ACTION)PRIMARY ACTION)Around the vertical axis – Around the vertical axis – Adduction ( tertiary)Adduction ( tertiary)Around the anteroposterior axis – Around the anteroposterior axis – Intortion Intortion (secondary)(secondary)

Action of the RECTIAction of the RECTI

Inferior rectusInferior rectus Around the transverse axis – rotates Around the transverse axis – rotates

the eyeball downwards – the eyeball downwards – DepressionDepression (PRIMARY ACTION) (PRIMARY ACTION)

Around the vertical axis – Around the vertical axis – AdductionAdduction Around the anteroposterior axis - Around the anteroposterior axis -

ExtortionExtortion

Action of the RECTIAction of the RECTI• Superior obliqueSuperior oblique Around the Around the

anteroposterior axis anteroposterior axis ––Intorsion(Intorsion(primary primary action)action)

Around the vertical Around the vertical axis axis AbductionAbduction

Around the Around the transverse eaxis – transverse eaxis – DepressionDepression

Action of the RECTIAction of the RECTI Inferior obliqueInferior oblique Extortion Extortion Around the Around the

anteroposterior axis anteroposterior axis ((primary action)primary action) Around the vertical axis Around the vertical axis AbductionAbduction Around the transverse eaxis Around the transverse eaxis

ElevationElevation

Action of the RECTIAction of the RECTI Both recti have same tertiary action bcz they Both recti have same tertiary action bcz they

inserted anterior to centre of rotationinserted anterior to centre of rotation

pull ant.portion of globe medially so it causes pull ant.portion of globe medially so it causes adductionadduction

Action of the RECTIAction of the RECTI Both obliques have same tertiary action Both obliques have same tertiary action

because inserted behind the center of rotation,because inserted behind the center of rotation, pull post. pole of globe medially pull post. pole of globe medially when they contract ant.portion of eye so it when they contract ant.portion of eye so it

causes abductioncauses abduction

Actions of EOMActions of EOM

ACTION PRIMARY SECONDARY TERTIARY

MR ADDUCTION ------ ---------

LR ABDUCTION ------ ---------

SR ELEVATION INTORSION ADDUCTION

IR DEPRESSION EXTORSION ADDUCTION

SO INTORSION DEPRESSION ABDUCTION

IO EXTORSION ELEVATION ABDUCTION

Action of extraocular musclesAction of extraocular muscles

Rotation around Rotation around center of center of rotationrotation3 types of rotation:3 types of rotation:1.1.Rotation around Rotation around vertical axis vertical axis Z—Z—side side to side.to side.2.2. Rotation around Rotation around horizontal axis X– horizontal axis X– up&downup&down3.3. Rotation around fick Rotation around fick antero posterior Y antero posterior Y axis– axis– torsiontorsion

movementsmovements

Abduction

Elevation

Depression

Adduction Intorsion

Extorsion

Elevation & Depression – Around the transverse axisAdduction & Abduction – Around the vertical axisIntortion & Extortion – Around the anteroposterior axis

Types of Eye MovementsTypes of Eye Movements

1.1. Uniocular Eye MovemntsUniocular Eye Movemnts Duction(Uniocular Eye Movements)Duction(Uniocular Eye Movements)1.1. Binocular Eye MovementsBinocular Eye Movements Version:Version: (Binocular Conjugate Eye (Binocular Conjugate Eye

Movements).Movements). Vergence:(Binocular Disjugate eye Vergence:(Binocular Disjugate eye

movements).movements).

Uniocular movementsUniocular movements

Ductions – only one eye is open, the other Ductions – only one eye is open, the other covered/closed tested by asking the pt. to follow a target covered/closed tested by asking the pt. to follow a target in each direction of gaze.in each direction of gaze.

Types of ductions:-Types of ductions:-1.1. AdductionAdduction2.2. AbductionAbduction3.3. SupraductionSupraduction4.4. InfraductionInfraduction5.5. IncycloductionIncycloduction6.6. excycloductionexcycloduction

Binocular movementsBinocular movements

VersionsVersions:-both eyes open, attempting to fixate :-both eyes open, attempting to fixate a target &moving in same direction.a target &moving in same direction.

Binocular ,simultaneous, conjugate Binocular ,simultaneous, conjugate movements in same direction.movements in same direction.

Abduction of one eye accompanied by Abduction of one eye accompanied by adduction of other eye is called adduction of other eye is called conjugate conjugate movementsmovements..

Binocular movementsBinocular movements

Types of versionsTypes of versions:-:- Dextroversion & laevo version Dextroversion & laevo version Elevation & depressionElevation & depression Dextro elevation & dextro depressionDextro elevation & dextro depression Laevo elevation & laevo depressionLaevo elevation & laevo depression

Binocular movementsBinocular movements

VergencesVergences:binocular,simultaneous,disjugate/:binocular,simultaneous,disjugate/disjunctive movements (opp.direction)disjunctive movements (opp.direction)Convergence– simultaneous adductionConvergence– simultaneous adductionDivergence– outward movement from Divergence– outward movement from convergent positionconvergent position

Diagnostic positions of gazeDiagnostic positions of gaze:-:-99

1 Primary position of gaze:-assumed by eyes when fixating a distant 1 Primary position of gaze:-assumed by eyes when fixating a distant object with head erect.object with head erect.

4 secondary 4 secondary 1.1. up,up,2.2. down, down, 3.3. Right, Right, 4.4. Left,Left, 4 tertiary positions4 tertiary positions1.1. Dextroelevation, Dextroelevation, 2.2. Dextrodepression, Dextrodepression, 3.3. Levoelevation Levoelevation 4.4. LevodepressionLevodepression

cardinal positions:-6cardinal positions:-6

6 cardinal positions :- to test 12 EOM in their 6 cardinal positions :- to test 12 EOM in their main field of actionmain field of action

1.1. DextroversionDextroversion2.2. Laevo versionLaevo version3.3. Dextro elevation Dextro elevation 4.4. Leavo elevationLeavo elevation5.5. Dextro depressionDextro depression6.6. Laevo depressionLaevo depression

Synergists, Antagonists, Contralateral Synergists, Antagonists, Contralateral antagonist, Yoke muscleantagonist, Yoke muscle

SynergistsSynergists:-ref.to muscles having same action in :-ref.to muscles having same action in same eye.same eye.

Ex:-sup.rectus & inf.oblique----elevatorsEx:-sup.rectus & inf.oblique----elevatorsinf.rectus&sup.oblique-----depressorsinf.rectus&sup.oblique-----depressors AntagonistsAntagonists:-having opp.action in same eye:-having opp.action in same eyeEx:-sup.&inf. Recti ,sup.&inf.obliqueEx:-sup.&inf. Recti ,sup.&inf.oblique Contralateral antagonistContralateral antagonist:-pair of muscle (one from :-pair of muscle (one from

each eye)having an opposite action.each eye)having an opposite action.Ex:-in dextroversion RLR & LLREx:-in dextroversion RLR & LLR

Yoke Yoke muscle(contralateral muscle(contralateral synergistssynergists):-):-

Ref. to muscles Ref. to muscles which are primary which are primary muscles (one from muscles (one from each eye) that each eye) that accomplish(contract) accomplish(contract) a given version.a given version.

Ex :-in dextroversion Ex :-in dextroversion RLR &LMRRLR &LMR

Laws of ocular motilityLaws of ocular motility

1.1. Hering’s law of equal innervationHering’s law of equal innervation:- during :- during any conjugate movement equal & any conjugate movement equal & simultaneous innervation flows to yoke simultaneous innervation flows to yoke musclesmuscles

Laws of ocular motilityLaws of ocular motility

2.2. Sherrington law of reciprocal innervation Sherrington law of reciprocal innervation :-:- increase innervation to an EOM is increase innervation to an EOM is

accompanied by reciprocal decrease in accompanied by reciprocal decrease in innervation to its antagonist.innervation to its antagonist.

Ex:-RMR & RLREx:-RMR & RLR