This document provides an overview of orbital and extraocular muscles: 1. It describes the anatomy, embryology, blood supply, nerve supply and actions of the 7 extraocular muscles - superior, inferior, medial and lateral rectus, superior and inferior oblique, and levator palpebrae superioris. 2. Key points about the rectus muscles include their origin, course, insertion locations on the sclera, and primary and secondary actions. 3. The oblique muscles intort and depress or extort and elevate the eyeball respectively as their primary actions. 4. Embryologically, the muscles develop from mesoderm and form a single muscle cone that later separates

1. ANATOMY OF
DR ASHISH BADGUJAR

2. ORBITAL MUSCLES
INTRA-OCULAR EXTRA- OCULAR
INVOLUNTARY VOLUNTARY
1.Superior tarsal muscle.
2.Inferior tarsal muscle
1.Levator Palpebrae Superioris
2.Superior rectus
3.Inferior rectus
4.Medial rectus
5.Lateral rectus
6.Superior oblique
7.Inferior oblique
• Ciliary muscle
• Sphicter pupillae
• Dilator pupillae

4. EMBRYOLOGY
• EOM develop from mesodermal derived mesenchyme
• Myoblasts which form EOM arise from cranial
paraxial mesoderm
• Orbital connective tissue - neural crest cells

5. EMBRYOLOGY
Premandibular
condensation
MR, SR, IR, IO
Maxillo-mandibular
mesoderm SO,LR

6. EMBRYOLOGY
•Development begins from muscle cone(annulus
of Zinn) at apex & proceeds anteriorly.
•Originally represented as a single mass of
mesenchyme.
•Later separate into distinct muscles.

7. EMBRYOLOGY
EOM appear in following sequence
•Lateral rectus, superior rectus ,LPS ( 5 week)
•Superior oblique ,Medial Rectus (6 week)
•Inferior oblique and inferior rectus follows
•By birth the orbital contents are comparable to
those in adult.

8. RECTI-ORIGIN
ANNULUS OF ZINN

9. RECTI
•Origin of superior &medial rectus are slightly at
anterior plane to others d/t slope of orbital roof
•SR&MR are closely attached to the dural sheath
of optic nerve at their origin
•In RBN pain upward & inward movement causes
pain

10. RECTI- COURSE
•Divergent from origin
•In front of the equator they turn towards the
eyeball & get inserted on sclera
•MR & LR follow the corresponding walls of the
orbit for most of the part
•IR remains in contact with floor for only half of
its length
•SR separated from roof by LPS

11. RECTI- INSERTION
SPIRALOFTILLAUX
All 4 recti inserted into
the sclera at diff distance
from limbus:
SR- 7.7mm
LR- 6.9mm
IR- 6.5mm
MR- 5.5 mm

12. RECTI- INSERTION
•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

13. SUPERIOR RECTUS
COURSE- • Passes
anterolaterally beneath
the levator at 23-25
degree with globes A-P
axis
•SR pierces tenons
capsule 15mm from its
insertion
• L—42mm
•W– 10.6mm

14. SUPERIOR RECTUS- RELATIONS
•Superiorly LPS & frontal nerve which separate SR
from roof of orbit
• Inferiorly ophthalmic A, nasociliary A & nerves are
separated by orbital fat
reflected tendon of SO passes bet SR & globe
• Laterally lacrimal artery &nerve are bet SR & LR
• Medially ophthalmic artery & nasociliary nerve
bet SR above and MR & SO below

15. SUPERIOR RECTUS
•NERVE SUPPLY- Sup div of oculomotor nerve,
entering ocular surface at junction of middle &
post 1/3rd
•BLOOD SUPPLY-The lateral muscular branch of
the ophthalmic artery

16. SUPERIOR RECTUS-ACTIONS
•PRIMARY- Elevation
•SECONDARY- adduction & intortion
•Globe abducted 230-VA & OA coincide
acts only as elevator, optimal posn to test fn
•Globe adducted 670-VA & OA at 900
acts only as intorter

18. INFERIOR RECTUS
•Shortest of the recti
•COURSE- Passes
anterolaterally along
the floor of orbit at
23-25 degree with A-
P axis of globe
•L—40mm
•W—9mm

19. INFERIOR RECTUS
•RELATIONS
•Superiorly separated from globe by Fat, optic
nerve, inferior division of oculomotor nerve
•Laterally nerve to IO runs on the lateral border
of IR
•Inferiorly floor of orbit, infraorbital vessels &
nerves;
•Inferior oblique crosses below the IR & their
sheaths are united here

20. INFERIOR RECTUS
•NERVE SUPPLY by branch of inf div of
oculomotor nerve, entering ocular surface
about 15 mm from its posterior end
•BLOOD SUPPLY medial muscular branch of
ophthalmic artery

21. INFERIOR RECTUS- ACTIONS
•PRIMARY- Depression
•SECONDARY- adduction & extortion
•Globe abducted 230-VA & OA coincide
acts only as depressor, optimal posn to test fn
•Globe adducted 670-VA & OA at 900
acts only as extorter

22. MEDIAL RECTUS
•Largest ocular muscle
• Stronger than LR
•40mm long & thicker than other EOM
•COURSE- passes along the medial wall of the
orbit inserts into the sclera 5.5mm from limbus

23. MEDIAL RECTUS
RELATIONS
•Superiorly is SO & between MR & SO,
Ophthalmic artery &its ethmoidal branch,
ethmoidal & infratrochlear nerves
•Inferiorly floor of the orbit
•Medially peripheral fat, orbital plate of the
ethmoid & ethmoidal sinuses
•Laterally is the central orbital fat & optic nerve

24. MEDIAL RECTUS
•NERVE SUPPLY a branch from inf div of the
oculomotor nerve enters the lateral surface
about 15mm from the orbital attachment of the
muscle
•BLOOD SUPPLY the medial muscular branch of
the ophthalmic artery
•Action adduction of the globe in the primary
position

25. LATERAL RECTUS
•Takes origin asTWO HEADS from lateral ends
of upper & lower tendon ring & adjoining part of
greater wing of sphenoid
•Two heads unite & run forwards along lateral
orbital wall
•Inserted into sclera 6.9mm from limbus
•The LR is often visible through the conjunctiva
& tenon’s capsule.

26. LATERAL RECTUS- RELATIONS
•At the apex of orbitTwo heads
of LR enclose a part of SOF
called as oculomotor foramen
•Structures passing through
this opening from ABOVE
DOWNWARDS are
•superior oculomotor division
•nasociliary nerve
•Inferior oculomotor division
•ophthalmic veins
•abducent nerve

27. LATERAL RECTUS
•Superiorly lacrimal artery(ant 2/3rd ) & nerve
(whole of its upper border)
•Inferiorly floor of orbit & tendon of IO passing
inferiorly & then medial to LR to its attachment
•Medially near apex abducent nerve, ciliary
ganglion, ophthalmic A are present btw LR &
optic nerve
•Nerve to IO lies btw LR & IR
•Laterally Periorbita, perimuscular fat, lacrimal
gland

28. LATERAL RECTUS
•NERVE SUPPLY- Abducent nerve enters ocular
aspect just post to its midpoint
•BLOOD SUPPLY- lateral muscular branch of
ophthalmic artery & lacrimal artery
•ACTION- Abduction of the globe in horizontal
plane

29. SUPERIOR OBLIQUE
•Longest &Thinnest muscle –
direct part (40mm) reflacted part
( 19.5mm)- total 59.5mm.
•ORIGIN- BOBY OF SPHENOID
from above & medial to optic
foramen.
•COURSE- moves forward btn
roof & medial part of orbit reach
TROCHLEA turns
posterolaterally.
•Reflected tendon passes under
the SR & fans out

30. SUPERIOR OBLIQUE
Insertion- onto the upper & outer part of sclera
behind the equator

31. SUPERIOR OBLIQUE
•NERVE SUPPLY-Trochlear nerve, after dividing
into 3-4 branches, enters SO superiorly & near
its lateral border in post half of its belly
•BLOOD SUPPLY- lateral muscular branch of the
ophthalmic artery

32. SUPERIOR OBLIQUE
ACTIONS-
•PRIMARY- intorsion
•SECONDARY- depression & abduction
ANTERIORFIBRES INTORSION
POSTERIOR FIBRES DEPRESSION

33. SUPERIOR OBLIQUE
ACTS AS DEPRESSOR ONLY CAN CAUSE INTORSION ONLY

34. INFERIOR OBLIQUE
•Shortest muscle- 37mm long
•Only EOM attached near front of the orbit
•ORIGINE- Originate as a rounded tendon from
the orbital plate of maxilla just lateral to orifice
of naso-lacrimalduct
•COURSE- It arcs laterally & posteriorly around
the globe passes btw IR & floor of the orbit

35. INFERIOR OBLIQUE
INSERTION- lower &
outer part of sclera
behind the equator.
Post end abt 1mm below
& 1-2mm in front of a
point corresponding with
the foveal region
LR

36. INFERIOR OBLIQUE
RELATIONS
•Superiorly fat & IR
•Inferiorly periosteum of the orbital floor
•Laterally LR & fascia bulbi
NERVE SUPPLY- Inf div of oculomotor which
crosses the midpt of its post border to enter IO
on sup surface

37. INFERIOR OBLIQUE
BLOOD SUPLLY- Medial muscular & infraorbital
branch ophphthalmic artery
ACTIONS
PRIMARY- Extorsion
SECONDARY- Elevation & abduction
510 adduction Only elevator
390 abduction Only extortion

38. BLOOD SUPPLY
OPHTHALMIC
ARTERY
Medial
Muscular
Artery
MR,IR,IO
Lateral
Muscular
Artery
LR,SR,SO,LPS
• Additional Ciliary
arteries also arises
from these musclar
arteries
• Seven branches
• Two for each recti
except lateral rectus
which recieves only
one branch

39. Long arrows-primary action
Short arrows-secondary action
Curved arrows-tertiary action

40. MUSCLE
PRIMARY
ACTION
SECONDARY
ACTION
TERTIARY
ACTION
MR ADDUCTION __________ ____________
LR ABDUCTION
__________
____________
SR ELEVATION INTORSION ADDUCTION
IR DEPRESSION EXTORSION ADDUCTION
SO INTORSION DEPRESSION ABDUCTION
IO EXTORSION ELEVATION ABDUCTION

41. Fascial sheaths of extraocular
muscles
•Separate membranous lining of the muscles
which blend anteriorly with the tenon’s capsule.
(OR)
•Parts of the orbital fascia, where the fascia bulbi
is pierced by an extraocular muscle which
clothes the muscle like a glove.

43. Fascial expansions of extraocular
muscles
LATERAL RECTUS
ZYGOMATIC BONE
LATERAL CHECK
LIGAMENT
MEDIAL RECTUS
LACRIMAL BONE
MEDIAL CHECK
LIGAMENT

44. Fascial expansions of extraocular
muscles
Superior rectus muscle
Levator palpebrae superioris
Inferior rectus muscle
Capsule palpebral fascia

45. Suspensory ligament of Lockwood
Fusion of medial rectus, inferior rectus,
inferior oblique and lateral rectus muscle
sheaths
It extends from posterior lacrimal crest to
lateral orbital tubercule

47. Superior transverse ligament of
whitnall
•condensation of superior sheaths of LPS with
reflected tendon of superior oblique muscle.
•It extends from trochlear pulley to the lacrimal
gland and its fossa.

48. Suspensory ligament of the fornices
•Superior is formed by superior rectus and LPS
•Inferior is formed by forward continuation of lid
retractors

49. PULLEY SYSTEM
•High resolution MRI
• Dense band of collagen & elastin
• Contain smooth muscle
• Capable of adjusting vector forces of EOM on
globe in various gazes

50. CLASSIFICATION
•Location: orbital or global
• Colour : red, intermediate or pale
• Innervational pattern: singly or multiple
innervation

51. Porter et all classification
•Orbital singly innervated fibres OSIF
•Orbital multiple innervated fibres OMIF
•Global red singly innervated fibres GRSIF
•Global intermediate singly innervated fibres
GISIF
•Global pale singly innervated fibres GPSIF
•Global multiply innervated fibres GMIF

52. BasicKinematics
 Positions of gaze
 Primary
 Secondary
 Tertiary
 Cardinal

53. Primarygaze
 Binocular vision with head erect;
object is at infinity and lies at the
intersection of the sagittal plane of the
head and a horizontal plane passing
through the centers of rotation of the
two eyeballs

54. Secondarygaze
Straight up(supraversion)
Straight down(infraversion)
Right(dextroversion)
Left (levoversion)

55. Tertiarygaze
Levoelevation
(L-SR/R-IO)
Dextroelevation
(R-SR/L-IO)
Dextrodepression
(R-IR/L-SO) Levodepression
(L-IR/R-SO)

56.  Examine EOM in its main field of action

57. CentreofRotation





The point around which the
eyeball performs rotatory
movements
It moves in a semicircle in
the plane of rotation
Called “space centroid”
In primary position, 13.5mm
behind the cornea
Myopic -- posterior
Hypermetropic -- anterior

58. LISTINGS’ PLANE
IMAGINARY CORONAL PLANE PASSINGATHROUGH CENTRE OF
ROTATION

59. FICK’S AXES
• X ( horizontal) axis
•Lies horizontally when head is
upright
•Elevation / Depression
•Y ( antero-posterior) axis
•Torsional movements
•Extorsion / Intorsion
•Z ( vertical axis)
•Adduction / Abduction

60. Visual axis
 Line of vision –fovea -
nodal point of the eye -
point of fixation
Optical axis
 Line - posterior pole -
centre of the cornea
Angle kappa
 Axis -5degree.

61. 


Medial and Lateral orbital walls - 45degree
The orbital axis - 23degree with the two walls
When the eyes are looking straight ahead the
visual axis forms an angle of 23 degree with the
orbital axis

62. •Agonist- Particular muscle - specific ocular
movement.Eg: Abduction in right eye-right
lateral rectus muscle
•Synergists- Muscles- same eye move the eye in
same direction.Eg: superior rectus and inferior
oblique as elevators.
•Antagonists- Muscles of the same eye - opposite
direction Eg: medial and lateral rectus

63. Yoke muscles
•These are pairs of muscles, one in each eye,
which contract simultaneously during version
movements.
Eg: right lateral rectus and left medial rectus –
dextroversion

64. YOLK
MUSCLES

65. Hering’s law of equal innervation
•For any binocular movement the
corresponding(YOKE) muscles receive equal and
simultaneous innervation
Sherrington’s law of reciprocal
innervation
•States that for any binocular movement the
direct antagonist recieves an equal and
simultaneous inhibition of its innervation

66. Ocular movements
 Monocular (Duction)
 Binocular
 Version
 Vergence

67. NINE GAZE POSITION

68. APPLIED ANATOMY
•Sclera is thinnest just behind insertion of recti
0.3mm
• All muscles are innervated from intraconal side
of belly of muscle except trochlear nerve which
supplies SO from extraconal side .so this nerve is
not affected in retrobulbar block
• MR only muscle with no fascial connections to
adjacent oblique muscles

69. APPLIED ANATOMY
• During strabismus surgery if MR is disinserted
& released from globe it can retract completely
behind the globe making retrieval difficult
•SR recession will pull levator also posteriorly
causing upperlid retraction &fissure widening
.so removal of fascial connections are important
during surgery

70. APPLIED ANATOMY
•The muscle cone divides the retrobulbar area
into intra conal and extra conal spaces.(Axial
proptosis/para axial proptosis).
•Paralytic squint- ocular deviation due to
complete or incomplete paralysis of one or
more EOM