SlideShare ist ein Scribd-Unternehmen logo
1 von 42
Downloaden Sie, um offline zu lesen
Physiology of eyelids and eyebrows
FARAH IFTIKHAR
Bsc(Hons) Optometry and Orthoptics
(Rawalpinidi Medical College Rawalpindi)
Gold medalist (RMC)
Bronze Medalist (UHS)
Lecture#2
Eyelids
and
Eyebrows
Eyebrows
• Coarse hairs overlie the superior orbital
margins
• Functions include
1.Shading of eye
2.Preventing perspiration from reaching the
eye
• Orbicularis muscle--depresses the
eyebrows
• Corrugator muscles--moves the eyebrows
medially
The Eyelids
• Protect the eye from injury and excessive
light by their closure
• assist in the distribution of tears over the
anterior surface of eyeball
• Maintains the integrity of corneal surface
• Maintain the proper position of globe
within the orbital contents
• Regulate the amount of light allowed to
enter the eye.
• Provide protection from airborne particles
• Coverage of the eyes during sleep
EYELID
MOVEMENT
• Lid opening
• Lid closure
• Blinking
• Voluntary blinking and winking
• Bell's Phenomenon
Lid Opening
• Upper Eyelid- Elevators
• Lower eyelid- Retractors
Upper lid Elevators
• Levator palperbrae superioris (the primary
elevator of the upper eyelid)
• The superior Palpebral muscle of Muller's
• Frontalis (acting as accessory elevator)
(Frontalis and Muller's become important
when the levator is defective)
Physiology of eyelids and eyebrows
Eyelid excrusion (during opening
movements
• In adults the upper eyelid is raised some
10-15mm from extreme downward gaze to
extreme upward gaze
Tone of levator Muscle
• In upward gaze, tone increases in both the
superior rectus muscle and the levator,
resulting in elevation of the visual axis and
elevation and retraction of the upper eyelid
Physiology of eyelids and eyebrows
Lower Lid retractors
• No true counterpart of the levator is
present and therefore the opening
movement depends upon several factors
• Traction exerted by the attachment of the
inferior rectus to the inferior tarsus
• Inferior palpebral muscle (identical to
Muller's muscle in the upper eyelid)
Physiology of eyelids and eyebrows
Dynamics of opening movement
• Opening of the upper eylid takes place
against gravity
• Opening movements of the upper and
lower eyelids begin in phase, although the
opening movement of lower eyelid is much
slower than that of the upper eyelid due to
lack of any direct muscular pull
• During opening Movement the upper lid
moves vertically upwards, while the lower
lid moves laterally in horizontal direction
Bilateral coordination and their
basis
• Opening movements of the eyelids are
bilateral,symmetrical,and identical in
direction and amplitude (although they
may be voluntarily inhibited on either side)
• So, the levator muscles of the two upper
eyelids behave as YOKE MUSCLES, in
that they act as a team or pair, obeys
Hering's law' of equal innervation
HERING'S LAW
• This implies that the innervational energy
reaching the one levator muscle is equal
to that reaching the other.
Reciprocal innervation pattern
• It exists between the levator muscle and
the orbicularis oculi muscle, i-e when
levator recieves maximum innervation
during opening,the orbicularis oculi
receives minimum innervation and vice
versa. Thus these muscles follow
'SHERRINGTON'S LAW' of reciprocal
innervation
Lid Closure
• Orbicularis oculi controls lid closure and is
supplied by the facial nerve
Upper lid versus lower lid during
closing movement
• Upper lid moves downwards (vertically) while the
lower lid moves medially (horizontally)
• Closing movement of both upper and lower
eyelids occur in phase, although the movement
of lower eyelid begins some 12-20 micro
seconds before the movement can be detected
in the upper eyelid
• Gravity does not play any role in downward
movement of upper eyelid during closing
Blinking
• Blinking can be devided into
• voluntary and
• Involuntary
• The involuntary blinks are further devided
into
• spontaneous
• Reflex blinks
Spontaneous blinking
• It is common form of blinking that occurs
without any obvious external stimulus or
voluntary willed efforts
• Spontaneous blinking is infrequent during
the first few months of life, yet the delicate
infant cornea does not suffer from dryness
• Average rate is 15 times per minute (12-
20)
• The blink rate is increased in
1.Extremely dry conditions
2.Strong air currents
3.Certain emotional stress situations
(surprise,anger or fight)
• A decreased blink rate occurs during times
of visual observations
• Present in blind, hence no retinal stimulus
is required
• No discontinuity of visual sensation during
blinking
• This helps the displacement of the tear
film to the lacrimal puncta which are
located on the medial side of lids
Course of events
• Relaxation of levator
• After 10msec relaxation of levator relaxation, a
train of high frequency synchronous activity
occurs in the pretarsal portion of orbicularis
• As the upper lid moves vertically down, the lower
lid moves medially in a horizontal
direction.However when the upper eyelid
touches the lower eyelid,the downward
movement of othe upper lid is also transmitted to
the lower lid and after contact the lower lid
moves
• During each blink, the upper eyelid covers
the center of pupil for a period of 0.10sec.
• Due to contraction of preseptal fibers, as
the upper eyelid reaches the limit of its
downward excrusion, electrical activity in
the orbicularis ceases and activity appears
in levator
Reflex Blinking
• Reflexly in response to a stimulus
Voluntary blinking and winking
• Is a willed coordinated closure and
opening movement of the eyelids in both
eyes
• The voluntary blink is under the control of
individual
• It is produced as a protective gesture
Winking
• Winking is unilateral voluntary lid closure
• It is part of facial expression
• Occasionally, a subject may learn to wink
with one eye but not with the other
• Both 'voluntary blinking and winking' are
produced by simultaneous contraction of
palpebral and orbital portions of orbicularis
BELL'S Phenomenon
• It is highly coordinated reflex in which
eyeball is rotated upward and outward on
closure of eyelids
• This is a protective mechanism
• On closure of eyelids,all electrical
activities in the levator cease and the
activity abruptly rises in the superior rectus
muscle and is inhibted in the inferior
rectus muscle
Physiology of eyelids and eyebrows
MCQS
1.Main Elevator of upper eyelid is
A)Frontalis
B)Muller's Muscle
C)Levator palpebrea superioris
D)None Of these
2)Frontalis Muscle helps in
A)Elevating the Upper eyelid
B)Elevating Lower Eye lid
C)Retracting Lower Eyelid
D)Elevating eyeball
3)Superior Muscle Helps in
A) Elevating Upper Eyelid
B)Elevating Lower Eye lid
C)Retracting Lower Eyelid
D)Elevating eyeball
4)Levator muscles of two eyelid follow which
law
A) Sherrington's Law
B)Herring's Law
C)Law of gravity
D)All of these
5)During closing movement which lid moves
12-20msec before the other one
A) Upper Eylid
B) Lower Eyelid
C)Both Moves simultaneously
Physiology of eyelids and eyebrows

Weitere ähnliche Inhalte

Was ist angesagt? (20)

Tear film
 Tear film Tear film
Tear film
 
Tear film and dynamics
Tear film and dynamics Tear film and dynamics
Tear film and dynamics
 
Anatomy of the eyelids
Anatomy of the eyelidsAnatomy of the eyelids
Anatomy of the eyelids
 
Anatomy and physiology of cornea
Anatomy and physiology of corneaAnatomy and physiology of cornea
Anatomy and physiology of cornea
 
Ciliary body
Ciliary bodyCiliary body
Ciliary body
 
Coats of eyeball
Coats  of  eyeballCoats  of  eyeball
Coats of eyeball
 
UVEAL TRACT
UVEAL TRACTUVEAL TRACT
UVEAL TRACT
 
Conjunctiva anatomy and physiology
Conjunctiva anatomy and physiologyConjunctiva anatomy and physiology
Conjunctiva anatomy and physiology
 
Anatomy of uvea
Anatomy of uveaAnatomy of uvea
Anatomy of uvea
 
Anatomy of anterior chamber
Anatomy of anterior chamberAnatomy of anterior chamber
Anatomy of anterior chamber
 
Vitreous humour
Vitreous humourVitreous humour
Vitreous humour
 
Anatomy & physiology of eyelids
Anatomy  & physiology of eyelidsAnatomy  & physiology of eyelids
Anatomy & physiology of eyelids
 
Corneal diseases
Corneal diseasesCorneal diseases
Corneal diseases
 
Corneal Diseases / abnormalities
Corneal Diseases / abnormalities Corneal Diseases / abnormalities
Corneal Diseases / abnormalities
 
Anatomy Of Cornea
Anatomy Of  CorneaAnatomy Of  Cornea
Anatomy Of Cornea
 
Corneal degeneration ppt
Corneal degeneration pptCorneal degeneration ppt
Corneal degeneration ppt
 
HUMAN Lens ANATOMY
HUMAN Lens ANATOMYHUMAN Lens ANATOMY
HUMAN Lens ANATOMY
 
anatomy of sclera
anatomy of sclera anatomy of sclera
anatomy of sclera
 
Conjunctiva
ConjunctivaConjunctiva
Conjunctiva
 
Tear film Dr Ferdous
Tear film Dr Ferdous  Tear film Dr Ferdous
Tear film Dr Ferdous
 

Ähnlich wie Physiology of eyelids and eyebrows

EYELID ANATOMY AND PHYSIOLOGY.pptx
EYELID ANATOMY AND PHYSIOLOGY.pptxEYELID ANATOMY AND PHYSIOLOGY.pptx
EYELID ANATOMY AND PHYSIOLOGY.pptxNISHA S.S
 
Anatomy and physiology of the eyelid
Anatomy and physiology of the eyelidAnatomy and physiology of the eyelid
Anatomy and physiology of the eyelidAlaa Farsakh
 
STRABISMUS new-WPS Office.pptx
STRABISMUS new-WPS Office.pptxSTRABISMUS new-WPS Office.pptx
STRABISMUS new-WPS Office.pptxyashabandil155
 
Supranuclear disorders of ocular motility
Supranuclear disorders of ocular motilitySupranuclear disorders of ocular motility
Supranuclear disorders of ocular motilityerameshita
 
Anatomy and physilogy of eye,nose and throat
Anatomy and physilogy of eye,nose and throatAnatomy and physilogy of eye,nose and throat
Anatomy and physilogy of eye,nose and throatDeeps Gupta
 
Physiology of Equilibrium
Physiology of EquilibriumPhysiology of Equilibrium
Physiology of EquilibriumDr. Shilpa M J
 
Extraocular muscles.pptx
Extraocular muscles.pptxExtraocular muscles.pptx
Extraocular muscles.pptxSundip Charmode
 
Supra nuclear eye movements
Supra nuclear eye movementsSupra nuclear eye movements
Supra nuclear eye movementsDesta Genete
 
Diseases of ocular motility
Diseases of ocular motilityDiseases of ocular motility
Diseases of ocular motilitymeducationdotnet
 
Physiology pupil and eom dr.mohammed
Physiology pupil and eom dr.mohammedPhysiology pupil and eom dr.mohammed
Physiology pupil and eom dr.mohammedmohammed muneer
 
Supranuclear disorders of ocular motility
Supranuclear disorders of ocular motilitySupranuclear disorders of ocular motility
Supranuclear disorders of ocular motilitySSSIHMS-PG
 
Physiolology of Eye: Power of Accommodation and Perimetry
Physiolology of Eye: Power of Accommodation and PerimetryPhysiolology of Eye: Power of Accommodation and Perimetry
Physiolology of Eye: Power of Accommodation and PerimetryShishirBadave
 

Ähnlich wie Physiology of eyelids and eyebrows (20)

EYELID ANATOMY AND PHYSIOLOGY.pptx
EYELID ANATOMY AND PHYSIOLOGY.pptxEYELID ANATOMY AND PHYSIOLOGY.pptx
EYELID ANATOMY AND PHYSIOLOGY.pptx
 
Anatomy and physiology of the eyelid
Anatomy and physiology of the eyelidAnatomy and physiology of the eyelid
Anatomy and physiology of the eyelid
 
Presentation.pdf
Presentation.pdfPresentation.pdf
Presentation.pdf
 
STRABISMUS new-WPS Office.pptx
STRABISMUS new-WPS Office.pptxSTRABISMUS new-WPS Office.pptx
STRABISMUS new-WPS Office.pptx
 
VISUAL REFLEXES.pptx
VISUAL REFLEXES.pptxVISUAL REFLEXES.pptx
VISUAL REFLEXES.pptx
 
squint copy.pptx
squint copy.pptxsquint copy.pptx
squint copy.pptx
 
Diseases of ocular motility with an emphasis on squint
Diseases of ocular motility with an emphasis on squintDiseases of ocular motility with an emphasis on squint
Diseases of ocular motility with an emphasis on squint
 
Supranuclear disorders of ocular motility
Supranuclear disorders of ocular motilitySupranuclear disorders of ocular motility
Supranuclear disorders of ocular motility
 
Anatomy and physilogy of eye,nose and throat
Anatomy and physilogy of eye,nose and throatAnatomy and physilogy of eye,nose and throat
Anatomy and physilogy of eye,nose and throat
 
Physiology of Equilibrium
Physiology of EquilibriumPhysiology of Equilibrium
Physiology of Equilibrium
 
Extraocular muscles.pptx
Extraocular muscles.pptxExtraocular muscles.pptx
Extraocular muscles.pptx
 
2 eye bony orbic and ball
2 eye bony orbic and ball2 eye bony orbic and ball
2 eye bony orbic and ball
 
Supra nuclear eye movements
Supra nuclear eye movementsSupra nuclear eye movements
Supra nuclear eye movements
 
strabismus
strabismusstrabismus
strabismus
 
Diseases of ocular motility
Diseases of ocular motilityDiseases of ocular motility
Diseases of ocular motility
 
Physiology pupil and eom dr.mohammed
Physiology pupil and eom dr.mohammedPhysiology pupil and eom dr.mohammed
Physiology pupil and eom dr.mohammed
 
Supranuclear disorders of ocular motility
Supranuclear disorders of ocular motilitySupranuclear disorders of ocular motility
Supranuclear disorders of ocular motility
 
Strabismus
Strabismus Strabismus
Strabismus
 
Special senses.ppsx
Special senses.ppsxSpecial senses.ppsx
Special senses.ppsx
 
Physiolology of Eye: Power of Accommodation and Perimetry
Physiolology of Eye: Power of Accommodation and PerimetryPhysiolology of Eye: Power of Accommodation and Perimetry
Physiolology of Eye: Power of Accommodation and Perimetry
 

Kürzlich hochgeladen

"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf
"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf
"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdfDolisha Warbi
 
Health literacies in marginalised communities LILAC 24.pptx
Health literacies in marginalised communities LILAC 24.pptxHealth literacies in marginalised communities LILAC 24.pptx
Health literacies in marginalised communities LILAC 24.pptxPamela McKinney
 
Three Keys to a Successful Margin: Charges, Costs, and Labor
Three Keys to a Successful Margin: Charges, Costs, and LaborThree Keys to a Successful Margin: Charges, Costs, and Labor
Three Keys to a Successful Margin: Charges, Costs, and LaborHealth Catalyst
 
Understanding Warts and Moles: Differences, Types, and Common Locations
Understanding Warts and Moles: Differences, Types, and Common LocationsUnderstanding Warts and Moles: Differences, Types, and Common Locations
Understanding Warts and Moles: Differences, Types, and Common LocationsNeha Sharma
 
Empathy Is a Stress Response - Choose Compassion instead
Empathy Is a Stress Response - Choose Compassion insteadEmpathy Is a Stress Response - Choose Compassion instead
Empathy Is a Stress Response - Choose Compassion insteadAlex Clapson
 
Assisted Living Care Residency - PapayaCare
Assisted Living Care Residency - PapayaCareAssisted Living Care Residency - PapayaCare
Assisted Living Care Residency - PapayaCareratilalthakkar704
 
Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....
Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....
Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....sharyurangari111
 
Hematinics and Erythropoietin- Pharmacology of Hematinics
Hematinics and Erythropoietin- Pharmacology of HematinicsHematinics and Erythropoietin- Pharmacology of Hematinics
Hematinics and Erythropoietin- Pharmacology of Hematinicsnetraangadi2
 
Introduction to Evaluation and Skin Benefits
Introduction to Evaluation and Skin BenefitsIntroduction to Evaluation and Skin Benefits
Introduction to Evaluation and Skin Benefitssahilgabhane29
 
Identifying Signs of Mental Health Presentation (1).pptx
Identifying Signs of Mental Health Presentation (1).pptxIdentifying Signs of Mental Health Presentation (1).pptx
Identifying Signs of Mental Health Presentation (1).pptxsandhulove46637
 
Living Well Every Day: Lyons Wellness Practice | Nurtures Your Complete Health
Living Well Every Day: Lyons Wellness Practice | Nurtures Your Complete HealthLiving Well Every Day: Lyons Wellness Practice | Nurtures Your Complete Health
Living Well Every Day: Lyons Wellness Practice | Nurtures Your Complete HealthLyons Health
 
ACCA Version of AI & Healthcare: An Overview for the Curious
ACCA Version of AI & Healthcare: An Overview for the CuriousACCA Version of AI & Healthcare: An Overview for the Curious
ACCA Version of AI & Healthcare: An Overview for the CuriousKR_Barker
 
Anatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdf
Anatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdfAnatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdf
Anatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdfhezamzaki1
 
Pharmacovigilance audits inspections.pptx
Pharmacovigilance audits inspections.pptxPharmacovigilance audits inspections.pptx
Pharmacovigilance audits inspections.pptxCliniminds India
 
FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES 11
FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES  11FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES  11
FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES 11crzljavier
 
NEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptx
NEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptxNEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptx
NEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptxHanineHassan2
 
person with disability and pwd act ppt.pptx
person with disability and pwd act ppt.pptxperson with disability and pwd act ppt.pptx
person with disability and pwd act ppt.pptxMUKESH PADMANABHAN
 
Diseases of the Respiratory System (J00-J99),.pptx
Diseases of the Respiratory System (J00-J99),.pptxDiseases of the Respiratory System (J00-J99),.pptx
Diseases of the Respiratory System (J00-J99),.pptxEMADABATHINI PRABHU TEJA
 

Kürzlich hochgeladen (20)

"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf
"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf
"ANATOMY AND PHYSIOLOGY OF THE SKIN".pdf
 
Health literacies in marginalised communities LILAC 24.pptx
Health literacies in marginalised communities LILAC 24.pptxHealth literacies in marginalised communities LILAC 24.pptx
Health literacies in marginalised communities LILAC 24.pptx
 
Three Keys to a Successful Margin: Charges, Costs, and Labor
Three Keys to a Successful Margin: Charges, Costs, and LaborThree Keys to a Successful Margin: Charges, Costs, and Labor
Three Keys to a Successful Margin: Charges, Costs, and Labor
 
Understanding Warts and Moles: Differences, Types, and Common Locations
Understanding Warts and Moles: Differences, Types, and Common LocationsUnderstanding Warts and Moles: Differences, Types, and Common Locations
Understanding Warts and Moles: Differences, Types, and Common Locations
 
Empathy Is a Stress Response - Choose Compassion instead
Empathy Is a Stress Response - Choose Compassion insteadEmpathy Is a Stress Response - Choose Compassion instead
Empathy Is a Stress Response - Choose Compassion instead
 
Assisted Living Care Residency - PapayaCare
Assisted Living Care Residency - PapayaCareAssisted Living Care Residency - PapayaCare
Assisted Living Care Residency - PapayaCare
 
Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....
Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....
Toothpaste for bleeding gums and sensitive teeth. Teeth whitening, Mouthwash....
 
Hematinics and Erythropoietin- Pharmacology of Hematinics
Hematinics and Erythropoietin- Pharmacology of HematinicsHematinics and Erythropoietin- Pharmacology of Hematinics
Hematinics and Erythropoietin- Pharmacology of Hematinics
 
Introduction to Evaluation and Skin Benefits
Introduction to Evaluation and Skin BenefitsIntroduction to Evaluation and Skin Benefits
Introduction to Evaluation and Skin Benefits
 
Painting Rats White Angers Them to No End
Painting Rats White Angers Them to No EndPainting Rats White Angers Them to No End
Painting Rats White Angers Them to No End
 
Identifying Signs of Mental Health Presentation (1).pptx
Identifying Signs of Mental Health Presentation (1).pptxIdentifying Signs of Mental Health Presentation (1).pptx
Identifying Signs of Mental Health Presentation (1).pptx
 
Living Well Every Day: Lyons Wellness Practice | Nurtures Your Complete Health
Living Well Every Day: Lyons Wellness Practice | Nurtures Your Complete HealthLiving Well Every Day: Lyons Wellness Practice | Nurtures Your Complete Health
Living Well Every Day: Lyons Wellness Practice | Nurtures Your Complete Health
 
ACCA Version of AI & Healthcare: An Overview for the Curious
ACCA Version of AI & Healthcare: An Overview for the CuriousACCA Version of AI & Healthcare: An Overview for the Curious
ACCA Version of AI & Healthcare: An Overview for the Curious
 
Anatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdf
Anatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdfAnatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdf
Anatomy Shelf Notevbhhhhhhhhhhhhhhhs.pdf
 
Pharmacovigilance audits inspections.pptx
Pharmacovigilance audits inspections.pptxPharmacovigilance audits inspections.pptx
Pharmacovigilance audits inspections.pptx
 
FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES 11
FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES  11FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES  11
FINAL PROJECT IN EMPOWERMENT TECHNOLOGIES 11
 
NEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptx
NEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptxNEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptx
NEONATAL RESPIRATORY CARE FROM A PHYSIO POV.pptx
 
person with disability and pwd act ppt.pptx
person with disability and pwd act ppt.pptxperson with disability and pwd act ppt.pptx
person with disability and pwd act ppt.pptx
 
Diseases of the Respiratory System (J00-J99),.pptx
Diseases of the Respiratory System (J00-J99),.pptxDiseases of the Respiratory System (J00-J99),.pptx
Diseases of the Respiratory System (J00-J99),.pptx
 
Annual Training
Annual TrainingAnnual Training
Annual Training
 

Physiology of eyelids and eyebrows

  • 2. FARAH IFTIKHAR Bsc(Hons) Optometry and Orthoptics (Rawalpinidi Medical College Rawalpindi) Gold medalist (RMC) Bronze Medalist (UHS)
  • 4. Eyebrows • Coarse hairs overlie the superior orbital margins • Functions include 1.Shading of eye 2.Preventing perspiration from reaching the eye
  • 5. • Orbicularis muscle--depresses the eyebrows • Corrugator muscles--moves the eyebrows medially
  • 6. The Eyelids • Protect the eye from injury and excessive light by their closure • assist in the distribution of tears over the anterior surface of eyeball • Maintains the integrity of corneal surface • Maintain the proper position of globe within the orbital contents
  • 7. • Regulate the amount of light allowed to enter the eye. • Provide protection from airborne particles • Coverage of the eyes during sleep
  • 9. • Lid opening • Lid closure • Blinking • Voluntary blinking and winking • Bell's Phenomenon
  • 10. Lid Opening • Upper Eyelid- Elevators • Lower eyelid- Retractors
  • 11. Upper lid Elevators • Levator palperbrae superioris (the primary elevator of the upper eyelid) • The superior Palpebral muscle of Muller's • Frontalis (acting as accessory elevator) (Frontalis and Muller's become important when the levator is defective)
  • 13. Eyelid excrusion (during opening movements • In adults the upper eyelid is raised some 10-15mm from extreme downward gaze to extreme upward gaze
  • 14. Tone of levator Muscle • In upward gaze, tone increases in both the superior rectus muscle and the levator, resulting in elevation of the visual axis and elevation and retraction of the upper eyelid
  • 16. Lower Lid retractors • No true counterpart of the levator is present and therefore the opening movement depends upon several factors • Traction exerted by the attachment of the inferior rectus to the inferior tarsus • Inferior palpebral muscle (identical to Muller's muscle in the upper eyelid)
  • 18. Dynamics of opening movement • Opening of the upper eylid takes place against gravity • Opening movements of the upper and lower eyelids begin in phase, although the opening movement of lower eyelid is much slower than that of the upper eyelid due to lack of any direct muscular pull
  • 19. • During opening Movement the upper lid moves vertically upwards, while the lower lid moves laterally in horizontal direction
  • 20. Bilateral coordination and their basis • Opening movements of the eyelids are bilateral,symmetrical,and identical in direction and amplitude (although they may be voluntarily inhibited on either side) • So, the levator muscles of the two upper eyelids behave as YOKE MUSCLES, in that they act as a team or pair, obeys Hering's law' of equal innervation
  • 21. HERING'S LAW • This implies that the innervational energy reaching the one levator muscle is equal to that reaching the other.
  • 22. Reciprocal innervation pattern • It exists between the levator muscle and the orbicularis oculi muscle, i-e when levator recieves maximum innervation during opening,the orbicularis oculi receives minimum innervation and vice versa. Thus these muscles follow 'SHERRINGTON'S LAW' of reciprocal innervation
  • 24. • Orbicularis oculi controls lid closure and is supplied by the facial nerve
  • 25. Upper lid versus lower lid during closing movement • Upper lid moves downwards (vertically) while the lower lid moves medially (horizontally) • Closing movement of both upper and lower eyelids occur in phase, although the movement of lower eyelid begins some 12-20 micro seconds before the movement can be detected in the upper eyelid • Gravity does not play any role in downward movement of upper eyelid during closing
  • 26. Blinking • Blinking can be devided into • voluntary and • Involuntary • The involuntary blinks are further devided into • spontaneous • Reflex blinks
  • 27. Spontaneous blinking • It is common form of blinking that occurs without any obvious external stimulus or voluntary willed efforts • Spontaneous blinking is infrequent during the first few months of life, yet the delicate infant cornea does not suffer from dryness • Average rate is 15 times per minute (12- 20)
  • 28. • The blink rate is increased in 1.Extremely dry conditions 2.Strong air currents 3.Certain emotional stress situations (surprise,anger or fight) • A decreased blink rate occurs during times of visual observations
  • 29. • Present in blind, hence no retinal stimulus is required • No discontinuity of visual sensation during blinking • This helps the displacement of the tear film to the lacrimal puncta which are located on the medial side of lids
  • 30. Course of events • Relaxation of levator • After 10msec relaxation of levator relaxation, a train of high frequency synchronous activity occurs in the pretarsal portion of orbicularis • As the upper lid moves vertically down, the lower lid moves medially in a horizontal direction.However when the upper eyelid touches the lower eyelid,the downward movement of othe upper lid is also transmitted to the lower lid and after contact the lower lid moves
  • 31. • During each blink, the upper eyelid covers the center of pupil for a period of 0.10sec. • Due to contraction of preseptal fibers, as the upper eyelid reaches the limit of its downward excrusion, electrical activity in the orbicularis ceases and activity appears in levator
  • 32. Reflex Blinking • Reflexly in response to a stimulus
  • 33. Voluntary blinking and winking • Is a willed coordinated closure and opening movement of the eyelids in both eyes • The voluntary blink is under the control of individual • It is produced as a protective gesture
  • 34. Winking • Winking is unilateral voluntary lid closure • It is part of facial expression • Occasionally, a subject may learn to wink with one eye but not with the other • Both 'voluntary blinking and winking' are produced by simultaneous contraction of palpebral and orbital portions of orbicularis
  • 35. BELL'S Phenomenon • It is highly coordinated reflex in which eyeball is rotated upward and outward on closure of eyelids • This is a protective mechanism • On closure of eyelids,all electrical activities in the levator cease and the activity abruptly rises in the superior rectus muscle and is inhibted in the inferior rectus muscle
  • 37. MCQS 1.Main Elevator of upper eyelid is A)Frontalis B)Muller's Muscle C)Levator palpebrea superioris D)None Of these
  • 38. 2)Frontalis Muscle helps in A)Elevating the Upper eyelid B)Elevating Lower Eye lid C)Retracting Lower Eyelid D)Elevating eyeball
  • 39. 3)Superior Muscle Helps in A) Elevating Upper Eyelid B)Elevating Lower Eye lid C)Retracting Lower Eyelid D)Elevating eyeball
  • 40. 4)Levator muscles of two eyelid follow which law A) Sherrington's Law B)Herring's Law C)Law of gravity D)All of these
  • 41. 5)During closing movement which lid moves 12-20msec before the other one A) Upper Eylid B) Lower Eyelid C)Both Moves simultaneously