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1. Kanwal Perveen Jamali
M.Phil Vision Science

2. Voluntary muscles
Involuntary muscles

3. 3 muscles.
Superior tarsal muscle.
Inferior tarsal muscle.
Orbitalis.

4. 7 In Number
Levator Palpebrae Superioris
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus
Superior Oblique
Inferior Oblique

5. ANATOMY OF EXTRAOCULAR MUSCLES

6. When the eye is looking straight a head at a fixed
point on the horizon with the head erect ( primary
position of gaze ), the visual axis forms an angle of 23
deg. With the orbital axis .
The action of the extraocular muscles depend on the
position of the globe at the time of muscle
contraction .

8. Primary action : of a muscle is it’s major
effect when the eye is in the primary
position .
Subsidiary actions : are the additional
effect which depend on the position of
the eye .

9. Listing plane : is an imaginary coronal plane passing
through the center of rotation of the globe. the globe
rotates on the X and Z axes of Fick, which intersect in
Listing plane.

12. Torsional movements ( wheel rotation ) on the Y ( sagittal) axis
which traverses the globe from front to back ( similar to the
anatomical axis of the eye .
Intorsion occurs when the superior limbus rotates nasally and
extorsion on temporal rotation .

13. The spiral is an imaginary line joining the
insertions of the four recti and is an important
anatomical land mark when performing
surgery .
SPIRAL OF TILLAUX

15. The insertions get further away from the Limbus and
make a spiral pattern .
1.Med.rectus 5.5 mm
2.Inf.rectus 6.5 mm
3.Lat. Rectus 6.9mm
4.Superior rectus 7.7 mm
SPIRAL OF TILLAUX

16. • The annulus of Zinn, also known as the annular tendon or
common tendinous ring, is a ring of fibrous tissue surrounding the
optic nerve at its entrance at the apex of the orbit.
• It is the origin for four of the seven extraocular muscles, omitting
the inferior oblique muscle.
• It can be used to divide the regions of the superior orbital fissure
• The arteries surrounding the optic nerve are sometimes called the
"circle of Zinn-Haller" ("CZH").
• This vascular structure is also sometimes called "circle of Zinn".
Parts
divided into two parts:
• A lower, the ligament or tendon of zinn, which gives origin to the
rectus inferior, part of the medial rectus , and the lower head of
origin of the rectus lateralis.
• An upper, which gives origin to the rectus superior, the rest of the
rectus medialis, and the upper head of the rectus lateralis. This
upper band is sometimes termed the superior tendon of lockwood.

17. 1. LEVATOR PALPEBRAE SUPERIORIS
Superior most muscle in the orbit.
Has voluntary and involuntary parts.

18. Origin-
Inferior surface of lesser wing of sphenoid.
Insertion-
1. Upper lamina-Anterior surface of superior tarsus
and skin of upper eyelid.
2. Middle lamina-superior margin of superior
tarsus.
3. Lower lamina-Superior conjunctival fornix
NERVE SUPPLY-
Upper division of occulomotor nerve.
Action:
Elevation of upper eyelid.

19. When the eye is in the primary position , the
horizontal recti are purely horizontal movers on
the vertical Z axis and have only primary actions
HORIZONTAL RECTUS MUSCLES

20. MEDIAL RECTUS : originates at the annulus of Zinn at the
orbital apex and inserts 5.5 mm behind the nasal limbus . it’s
sole primary action is adduction .

21. LATERAL RECTUS : originates at the annulus of Zinn and inserts
6.9 mm Behind the temporal limbus .it’s sole primary action is
abduction .

22.  The vertical recti run in line with the orbital
axis and are inserted in front of the equator .
They therefore form an angle of 23 deg. With
the visual axis .
VERTICAL RECTUS MUSCLES

24. originates from the upper part of the annulus of Zinn and
inserts 7.7mm behind the superior limbus.
The primary action is elevation , secondary actions are
adduction and intorsion .
when the globe is abducted 23 deg. The visual and orbital axes
coincide . In this position it has no subsidiary actions and can
only act as elevator
SUPERIOR RECTUS :

25.  This is therefore the optimal position of the globe for testing
the function of the superior rectus muscle .
If the globe was adducted 67 deg., the angle between the
visual axis and orbital axis would be 90 deg. In this position the
superior rectus could only act as intorter .

26. originates at the lower part of the annulus of Zinn
and inserts 6.5 mm behind the inferior limbus .
The primary action is depression , secondary actions
are adduction and extorsion.
When the globe is abducted 23 deg. The inferior
rectus acts purely as a depressor.
INFERIOR RECTUS

28. As for superior rectus , this is the optimal position of
the globe for testing the function of the inferior rectus
muscle .
If the globe was adducted 67 deg. The inferior rectus
could only act as an extortor .

29.  The obliques are inserted behind the equator and form an angle
of 51 deg with the visual axis .
OBLIQUE MUSCLES

30. Originates superomedial to
the optic foramen. It passes
forward through the trochlea
at the angle between the
superior and medial walls and
is then reflected backwards
and laterally to insert in the
posterior upper temporal
quadrant of the globe
SUPERIOR
OBLIQUE

31. The primary action of the superior oblique is
intorsion, secondary actions are depression and
abduction .
The anterior fibers of the superior oblique tendon are
primarily responsible for intorsion and the posterior
fibers for depression , allowing separate surgical
manipulation of these two actions .

32.  When the globe is adducted 51 deg. The visual axis
coincide with the line of pull of the muscle . In this
position it can only act as a depressor . This is
therefore , the best position of the globe for testing
the action of the superior oblique muscle.
 Thus , although the superior oblique has an
abducting action in primary position , the main effect
of the superior oblique weakness is seen as failure of
depression in adduction .

33. When the eye is abducted 39 deg. The visual axis and
the superior oblique make an angle of 90 deg. With
each other .
In this position the superior oblique can only cause
intorsion .

35. Originates from a small depression just behind the
orbital rim lateral to the lacrimal sac .
It passes backward and laterally to insert in the
posterior lower temporal quadrant of the globe , close
to the macula.
The primary action is extorsion , secondary actions are
elevation and abduction
INFERIOR OBLIQUE

36.  When the globe is adducted 51 deg. , the inferior
oblique acts only as an elevator .
 When the eye is abducted 39 deg. , it’s main action is
extorsion .

38. Muscle primary action secondary action tertiary action testing position
LR abduction none none abduction
MR adduction none none adduction
SR elevation intortion adduction up and out
IR depression extortion adduction down and out
IO extortion elevation abduction up and in
SO intortion depression abduction down and in

39. Ophthalmic artery.
Medial muscular branch-inferior rectus,
inferior oblique, medial rectus
Lateral muscular branch-superior rectus
superior oblique, lateral rectus.