Dr. Abdikarem Mohamoud Mohamed

1. Eye Muscles and Ocular Movements,
Laws of ocular Motility
Dr. Abdikariim Mohamoud MoahmedDr. Abdikariim Mohamoud Moahmed
University Of HargeisaUniversity Of Hargeisa
Hargeisa. SomalilandHargeisa. Somaliland

2. 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

3. Extraocularmusles(EOM)Extraocularmusles(EOM)
 They areThey are sixsix in numberin number
Four recti:Four recti:
 Superior rectusSuperior rectus
 Inferior rectusInferior rectus
 Medial rectusMedial rectus
 Lateral rectusLateral rectus
Two oblique musclesTwo oblique muscles:-:-
 Superior obliqueSuperior oblique
 Inferior obliqueInferior oblique

4. Action of the RECTIAction of the RECTI
Medial & lateral recti liein thesamehorizontal plane
Around avertical axis
Medial rectus - adduction Lateral rectus- abduction

5. Action of the RECTIAction of the RECTI
SuperiorrectusSuperiorrectus
Around thetransverseaxis– rotatestheeyeball upwardsAround thetransverseaxis– rotatestheeyeball upwards ––
Elevation(Elevation(PRIMARYACTION)PRIMARYACTION)
Around thevertical axis–Around thevertical axis– Adduction ( tertiary)Adduction ( tertiary)
Around theanteroposterior axis–Around theanteroposterior axis– Intortion (secondary)Intortion (secondary)

6. Action of the RECTIAction of the RECTI
 InferiorrectusInferiorrectus
 Around thetransverseaxis– rotatestheAround thetransverseaxis– rotatesthe
eyeball downwards–eyeball downwards– DepressionDepression (PRIMARY(PRIMARY
ACTION)ACTION)
 Around thevertical axis–Around thevertical axis– AdductionAdduction
 Around theanteroposterior axis-Around theanteroposterior axis- ExtortionExtortion

7. Action of the RECTIAction of the RECTI
• SuperiorobliqueSuperioroblique
 Around theAround the
anteroposterior axisanteroposterior axis
––Intorsion(Intorsion(primaryprimary
action)action)
 Around the verticalAround the vertical
axisaxis AbductionAbduction
 Around theAround the
transverse eaxis–transverse eaxis–
DepressionDepression

8. Action of the RECTIAction of the RECTI
 InferiorobliqueInferioroblique
 ExtortionExtortion Around theAround the
anteroposterior axisanteroposterior axis
((primary action)primary action)
 Around the vertical axisAround the vertical axis
AbductionAbduction
 Around thetransverseAround thetransverse
eaxiseaxis ElevationElevation

9. Action of the RECTIAction of the RECTI
 Both recti have same tertiary action bcz theyBoth 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 causespull ant.portion of globe medially so it causes
adductionadduction

10. Action of the RECTIAction of the RECTI
 Both obliques have same tertiary actionBoth obliques have same tertiary action
because inserted behind the center of rotation,because inserted behind the center of rotation,
 pull post. pole of globe mediallypull post. pole of globe medially
 when they contract ant.portion of eye so itwhen they contract ant.portion of eye so it
causes abductioncauses abduction

11. 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

12. Action of extraocular musclesAction of extraocular muscles
Rotation aroundRotation around
centerof rotationcenterof rotation
3 types of rotation:3 types of rotation:
1.1.Rotation aroundRotation around
vertical axisvertical axis Z—Z—sideside
to side.to side.
2.2. Rotation aroundRotation around
horizontal axis X–horizontal axis X–
up&downup&down
3.3. Rotation around fickRotation around fick
antero posterior Yantero posterior Y
axis–axis– torsiontorsion

13. movementsmovements
Abduction
Elevation
Depression
Adduction Intorsion
Extorsion
Elevation &Depression – Around the transverse axis
Adduction &Abduction – Around the vertical axis
Intortion &Extortion – Around the anteroposterioraxis

14. 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 eyeVergence:(Binocular Disjugate eye
movements).movements).

15. Uniocular movementsUniocular movements
 Ductions – only one eye is open, the otherDuctions – only one eye is open, the other
covered/closed tested by asking the pt. to follow acovered/closed tested by asking the pt. to follow a
target in each direction of gaze.target in each direction of gaze.
 Types of ductions:-Types of ductions:-
1.1. AdductionAdduction
2.2. AbductionAbduction
3.3. SupraductionSupraduction
4.4. InfraductionInfraduction
5.5. IncycloductionIncycloduction
6.6. excycloductionexcycloduction

17. 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, conjugateBinocular ,simultaneous, conjugate
movements in same direction.movements in same direction.
 Abduction of one eye accompanied byAbduction of one eye accompanied by
adduction of other eye is calledadduction of other eye is called conjugateconjugate
movementsmovements..

18. Binocular movementsBinocular movements
Types of versionsTypes of versions:-:-
 Dextroversion & laevo versionDextroversion & laevo version
 Elevation & depressionElevation & depression
 Dextro elevation & dextro depressionDextro elevation & dextro depression
 Laevo elevation & laevo depressionLaevo elevation & laevo depression

20. Binocular movementsBinocular movements
VergencesVergences:binocular,simultaneous,disjugate/disj:binocular,simultaneous,disjugate/disj
unctive movements (opp.direction)unctive movements (opp.direction)
Convergence– simultaneous adductionConvergence– simultaneous adduction
Divergence– outward movement fromDivergence– outward movement from
convergent positionconvergent position

21. Diagnostic positions of gazeDiagnostic positions of gaze:-:-99
 1 Primary position of gaze:-assumed by eyes when fixating a1 Primary position of gaze:-assumed by eyes when fixating a
distant object with head erect.distant object with head erect.
 4 secondary4 secondary
1.1. up,up,
2.2. down,down,
3.3. Right,Right,
4.4. Left,Left,
 4 tertiary positions4 tertiary positions
1.1. Dextroelevation,Dextroelevation,
2.2. Dextrodepression,Dextrodepression,
3.3. LevoelevationLevoelevation
4.4. LevodepressionLevodepression

22. cardinal positions:-6cardinal positions:-6
 6 cardinal positions :- to test 12 EOM in their6 cardinal positions :- to test 12 EOM in their
main field of actionmain field of action
1.1. DextroversionDextroversion
2.2. Laevo versionLaevo version
3.3. Dextro elevationDextro elevation
4.4. Leavo elevationLeavo elevation
5.5. Dextro depressionDextro depression
6.6. Laevo depressionLaevo depression

23. Synergists, Antagonists, ContralateralSynergists, Antagonists, Contralateral
antagonist, Yoke muscleantagonist, Yoke muscle
 SynergistsSynergists:-ref.to muscles having same action:-ref.to muscles having same action
in same eye.in same eye.
 Ex:-sup.rectus & inf.oblique----elevatorsEx:-sup.rectus & inf.oblique----elevators
inf.rectus&sup.oblique-----depressorsinf.rectus&sup.oblique-----depressors
 AntagonistsAntagonists:-having opp.action in same eye:-having opp.action in same eye
Ex:-sup.&inf. Recti ,sup.&inf.obliqueEx:-sup.&inf. Recti ,sup.&inf.oblique
 Contralateral antagonistContralateral antagonist:-pair of muscle (one:-pair of muscle (one
from each eye)having an opposite action.from each eye)having an opposite action.
Ex:-in dextroversion RLR & LLREx:-in dextroversion RLR & LLR

24.  YokeYoke
muscle(contralateralmuscle(contralateral
synergistssynergists):-):-
 Ref. to musclesRef. to muscles
which are primarywhich are primary
muscles (one frommuscles (one from
each eye) thateach eye) that
accomplish(contract)accomplish(contract)
a given version.a given version.
 Ex :-in dextroversionEx :-in dextroversion
RLR &LMRRLR &LMR

26. 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 yokesimultaneous innervation flows to yoke
musclesmuscles

27. Laws of ocular motilityLaws of ocular motility
2.2. Sherrington law of reciprocal innervationSherrington law of reciprocal innervation :-:-
 increase innervation to an EOM isincrease innervation to an EOM is
accompanied by reciprocal decrease inaccompanied by reciprocal decrease in
innervation to its antagonist.innervation to its antagonist.
 Ex:-RMR & RLREx:-RMR & RLR