extraocular muscles in a simplest and easy way for the students of eye care ophthalmology and optometry on fingertips .

1. EXTRAOCULAR MUSCLES
BY: Shoaib Khattak
BS optometry
Pico HMC Peshawar

2. Contents
• Orbital muscles
• Introduction to EOM
• Anatomy of EOM
• Extra Ocular Muscles
• Blood supply
• Nerve supply
• Functions of EOM
• Wholesome

3. Orbital muscles
extraocular
Involuntary
Superiortarsal
muscle
Inferiortarsal
muscles
Voluntary
LPS
IO,SO,SR,IR,MR,LR
intraocular Cilliary muscles

4. Introduction to extra ocular muscles
• The extraocular muscles are located with in the orbit
but are extrinsic and separate from the eyeball itself.
• There are six extraocular muscles(4 rectus and 2
oblique) that control the movement of eyeball and one
muscle(LPS) that control eyelid elevation.

5. Anatomy
• The EOM are striated muscles.
• They contain slow fibres that creates a graded
contraction on the exterior surface and fast muscle
fibres that produces rapid movement on anterior
surface.
• The muscle fibres contain high content of
mitochondria and oxidative enzymes .

6. • They also contains high amount of glycogen and
glycolated enzymes .
• EOM contains palisade endings which are believed to
act as a sensory receptors that passes signals to CNS
to maintain muscle tension .

7. SUPERIOR RECTUS
• This muscle originates from the superior portion of
annulus of zinn.
• Courses forward from approx. 42 mm along the dorsal
aspect of the globe .
• Forms an angle of 23 * with the axis of the globe.
• Superiorly it is in close contact with levator muscle .
• The muscle is inserted at 7.7 mm from the limbus with
a width of 11mm .

8. • Function
• Its primary function is elevation
• Secondary function is intorsion
• Tertiary function is adduction
• Nervesupply
• The superior rectus is supplied by superior division of
oculomotor nerve .
• Bloodsupply
• Superior rectus primarily supplied by superior
muscular branch of ophthalmic artery and the two
anterior cilliary arteries .

9. INFERIOR RECTUS
• The IR muscle arises from the inferior portion of
annulus of zinn.
• Courses forward for approximately 42 mm along the
ventral aspect of the globe .
• Insertion is about 6.5 mm from the limbus .
• Width of the insertion is around 10mm.

10. • Nervesupply
• The IR muscle is innervated by the inferior division of
oculomotor nerve .
• Bloodsupply
• Blood supply is primarily from the inferior muscular
branch of ophthalmic artery + infraorbital artery .
• Function
• Primary ; depression
• Secondary ; extorsion
• Tertiary ; adduction

12. MEDIAL RECTUS
• The MR originatesat the orbitalapex from he medialportionof
annulus of zinnin close contactwiththe optic nerve .
• It coursesforward for approx.40mm alongthe medialaspectof
the globe .
• Onlythe last5mmof the MR are in contactwiththe eyeball.
• MR is inserted around5.5mm from the limbus withthe widthof
10.50mm.

13. • Nervesupply
• The MR muscle is innervatedby the inferiordivisionof
oculomotor nerve.
• Bloodsupply
• The MR muscle receiveits bloodsupply fromthe inferior
muscularbranchof ophthalmicartery.
• Function
• Its functionis to adductthe eye towards nose .

14. LATERAL RECTUS
• The lateral rectus muscle arises from upper and
lower portions of annulus of zinn.
• Courses forward for approx. 40mm along the lateral
aspect of the globe and crosses the insertion of
inferior oblique muscle .
• It penetrates the tenon’s capsule at 15mm from
insertion.
• The last 7-8 mm of the muscle is in contact with the
eye.
• The LR muscle is inserted around 7mm from the
limbus with a width of about 9.5mm.

15. • Nerve supply
• The LR muscle is innervated by VI cranial nerve the
abducens nerve.
• Bloodsupply
• The LR muscle receive its blood supply from the
inferior muscular branch of ophthalmic artery .
• The LR also receive blood supply from lacrimal artery.
• Function
• Its function is to move the eyes in lateral direction i.e
abduction of the eyeball.

16. SUPERIOR OBLIQUE
• The SO muscle arises from the orbital apex from
periosteum of the body of sphenoid bone.
• Courses forward approx. 40mm along the medial wall
of the orbit to the trochlea ( a v-shaped fibrocartilage
attached to the frontal bone ).
• The muscle is encased in synovial sheath.
• Form an angle of about 51* with the visual axis .
• Passes beneath the superior rectus and inserts on the
upper temporal quadrant of the globe .

17. • Nervesupply
• The SO muscle is innervatedby the trochlearnervethatenters
the muscleon its surface roughly12 mm from its origin.
• Bloodsupply
• The SO muscle is supplied by superiormuscularbranchof the
ophthalmicartery.
• Function
• Primary; intorsion
• Secondary; depression
• Tertiary; abduction

18. INFERIOR OBLIQUE
• The IO muscle arisesfrom the floorof the orbitfrom the
periosteumcoveringthe anteromedial portionof the maxillary
bone.
• It is the onlymusclethat’s notoriginatedfrom the annulusof zinn.
• Courseslaterallyand posteriorlyapprox. 37mm.
• Formsan angleof 51* withthe visualaxis.
• Insertedunderthe lateralrectus justanteriorto the macular
area.

19. • Nervesupply
• The IO muscle is suppliedby the inferiordivisionof oculomotor
nerve.
• Bloodsupply
• Inferioroblique is supplied by the ophthalmicartery and
infraorbital artery,these arise from the internalcarotidand
maxillaryarteries,respectively.
• Function
• Primary; extorsion
• Secondary; elevation
• Tertiary; abduction

20. LEVATOR PALPEBRAE SUPERIORIS
• The LPS muscle arisesfrom undersurface of the lesserwingof
sphenoidbone .
• InsertedintoSuperior tarsalplate,skinof uppereyelid
• As an extraocular muscle,levator palpebraesuperioris indirectly
facilitates movementsof the eye by elevatingand retractingthe
uppereyelid .
• It allows unhinderedupwardgaze.
• As a facialmuscle,it contributesto the arrayof facial
expressions.

21. • Nervesupply
• The LPS receivesits nerve supplyfrom superiordivisionof
Oculomotornerve (CN III).
• Bloodsupply
• Receive its bloodsupplyfrom Ophthalmicarteryand supraorbital
artery.
• Function
• The LPS muscle helpsin Elevatingthe upper eyelid

22. Summary

23. Muscle Course or
length
Origin Insertion Angle Nerve
supply
Blood
supply
Function
Medial
rectus
40 mm Annulus
of zinn
5.5mm to
limbus
90 Lower
CNIII
Inferior
muscular
branch
adduction
Lateral
rectus
40mm Annulus
of zinn
6.9mm to
limbus
90 CNVI Superior
muscular
branch
Abductio
n
Superior
rectus
40mm Annulus
of zinn
7.7mm to
limbus
23 Upper
CNIII
Superior
muscular
branch
Elevation,
intorsion,
adduction
Inferior
rectus
40mm Annulus
of zinn
6.5mm to
limbus
23 Lower
CNIII
Inferior
muscular
branch
Depressio
n,extorsio
n,adducti
on
Superior
oblique
32mm Orbital
apex
above
annulus
of zinn
Post to
equator
of eyeball
51 CNIV Superior
muscular
branch
Intorsion,
depressio
n,abducti
on
Inferior
oblique
37mm Behind
lacrimal
Macular
area
51 Lower
CNIII
Inferior
muscular
Extort,ele
vates,abd

24. Thank you
for
your
Kind
attention