Extraocular muscle- lecture ppt

1. Figure 1.
Figure 2.
Figure 3.
Figure 4 .
Write down the answers
In the Figures 1-4
1. Which eye is abnormal ?
2. What is the abnormality ?
3. Name the cranial nerve involved.
4. Name the muscles supplied by that cranial
nerve

2. EXTRAOCULAR MUSCLES

3. Extraocular muscles
4 Recti and 2 Obliques
Superior rectus Superior oblique
Inferior rectus Inferior oblique
Medial rectus
Lateral rectus
Levator palpebrae superioris

4. LEVATOR PALPEBRAE SUPERIORIS
Origin:
Undersurface of lesser wing of
sphenoid above optic canal
Insertion:
 Skin of upper eyelids
Anterior surface of superior tarsus
Muller`s muscle/Superior tarsal
muscle
Superior conjunctival fornix

7. LEVATOR PALPEBRAE SUPERIORIS
Nerve supply and Actions
Paralysis - PTOSIS
Oculomotor nerve, Sympathetics
Elevates upper lid

8. Equator
Optical axis/Axis of Gaze – direction of
sight .Primary position of eye
Axis of movements
Axis of muscles

9. Movements
Abduction
Elevation
Depression
Adduction Intorsion
Extorsion
Elevation & Depression – Around the transverse axis
Adduction & Abduction – Around the vertical axis
Intortion & Extortion – Around the anteroposterior axis

10. And the RULE is…..(for recti and oblique)
Any muscle inserting
medial to vertical axis – Adduction
lateral to vertical axis - Abduction
superior to AP axis – Intorsion
inferior to AP axis – Extorsion
For muscle inserting in front of equator i.e RECTI
above transverse axis – Elevation
below transverse axis - Depression

11. ORIGIN OF THE 4 RECTI MUSCLE
Common tendinous ring
(Annulus of Zinn)
•Lateral rectus by 2
heads
–Extra head from
adjoining greater
wing of sphenoid
LEFT EYE

12. COURSE OF THE 4 RECTI
Muscular cone
Corresponding
wall of orbit
Rectus muscle length – 40mm
Innervated from intraconal
side of the muscle belly at the
junction of anterior 2/3 and
posterior 1/3 of the muscle

13. INSERTION OF THE 4 RECTI
The line connecting the insertion of the
recti in series is spiral & is known as spiral
line of Tillaux
Pierce
Tenon’scapsule
Sclera in front of the
equator
Medial rectus is susceptible to injury during anterior segment
procedures

14. AXES OF THE RECTI MUSCLE
Medial and lateral recti in same
horizontal plane
Superior and inferior recti in same
oblique plane, 25⁰lateral to optical
axis
In the abducted eye the axes
coincide

15. Action of the RECTI
• Medial & lateral recti lie in the same horizontal plane
Around a vertical axis
Medial rectus - adduction Lateral rectus -
abduction

16. • Superior rectus
 Around the transverse axis – rotates the
eyeball upwards – Elevation (PRIMARY
ACTION)
 Around the vertical axis - Adduction
 Around the anteroposterior axis -
Intortion
• Inferior rectus
 Around the transverse axis – rotates the
eyeball downwards – Depression (PRIMARY
ACTION)
 Around the vertical axis – Adduction
 Around the anteroposterior axis - Extortion

17. Only in the Abducted position of the eyeball the visual axis coincides with
the axis of superior and inferior recti
In abducted eye
Superior rectus – Elevation only
Inferior rectus - Depression only

18. Superior Oblique muscle
Body of sphenoid above and medial
to optic canal
Winds around trochlea at
superomedial part of orbit
(functional origin)
Insertion behind the equator
Postero‐superior quadrant
Only eye muscle innervated on the outer
surface of muscle belly.
Retrobulbar anaesthetic block

19. Origin from orbital surface of
maxilla
Passes backward and laterally
below inferior rectus
Insertion behind equator
parallel to superior oblique
Postero‐superior quadrant
Inferior Oblique Muscle
The oblique muscles always course below the corresponding vertical
rectus muscle

20. Axis of the Oblique Muscles
The obliques lie in
the same oblique
plane 51⁰medial to
optical axis
In the adducted eye
axes coincide with
the optical axis

21. • Superior oblique
 Around the anteroposterior axis –
Intorsion(primary action)
 Around the vertical axis Abduction
 Around the transverse eaxis –
Depression
• Inferior oblique
 Extortion(primary action)
 Abduction
 Elevation

22. Only in the Adducted position of the eyeball the visual axis coincides with the axis of
superior and inferior oblique
In Adducted eye
Superior oblique – Depression only
Inferior oblique – Elevation only

23. Superior division of oculomotor:- levator palpebrae superioris, superior rectus
Inferior division of oculomotor:- medial rectus, inferior oblique, inferior rectus
Trochlear nerve - superior oblique
Abducent nerve - lateral rectus
Nerve Supply of Extraocular Muscles

24. Blood supply
Ophthalmic artery

25. Extraocular Muscles
 Allow accurate positioning of visual axis
 Determine the spatial relationship
between the two eyes
 Responsible for binocular vision
 Have the smallest motor unit among
skeletal muscles – ratio of nerve fibre to
muscle fibre is 1:2(whereas 1:25 in
other skeletal muscles)
 -Yoke Muscles: a muscle of one eye is
paired with another muscle of the fellow
eye to produce a cardinal gaze
-Example: Right LR & Left MR
while looking towards right side
 They develop from ?
Preotic/preoccipital somitomeres

26. Fascial expansions of Extraocular muscles

27. RECTI -Adduct
OBLIQUES – Abduct
SUPERIORS – Intort
INFERIORS -Extort

28. Clinical Testing

29. Ptosis
Eyeball turned down and out
Ocular movements restricted
Pupil fixed and dilated
Loss of accomodation
OCCULOMOTOR NERVE PALSY

30. ABDUCENS PALSY – Internal squint
The right eye unable to abduct
External squint- Medial rectus paralysis
The right eye unable to adduct
OPTHALMOPLEGIA / EXTRAOCULAR MUSCLE PALSY
Injury to III, IV, VI cranial nerve Muscle paralysis
Unilateral paralysis produces Strabismus /Squint, Diplopia
TROCHLEAR NERVE
PALSY
Eyeball turned upwards
and inwards

34. TROCHLEAR NERVE PALSY
 Affected eye rotated up and in.
 Attempts to compensate lead to the patient tilting their head to the contralateral side.

35. ABDUCENS PALSY

45. Third nerve palsy results in an inability to move
the eye normally in all directions. Injury to the
third nerve can occur anywhere along its path,
from where it originates within the brain to
where it innervates the muscles that move the
eyeball. Third nerve palsy prevents the proper
functioning of the medial, superior, and
inferior recti, and inferior oblique muscles. As
a result, the eye cannot move up, down, or in.
When at rest, the eye tends to look down and
to the side, due to an inequality of muscle
functioning. The muscle responsible for
keeping the upper eyelid open (levator
palpebrae superioris) is also affected, resulting
in a drooping upper eyelid (ptosis

47. Movements
Elevation
Depression
Adduction
Abduction
Intortion extortion

48. phthalmoplegia, also called extraocular muscle palsy, paralysis of the
extraocular muscles that control the movements of the eye. Ophthalmoplegia usually involves the third (oculomotor), fourth
(trochlear), or sixth (abducens)cranial nerves. Double vision is the characteristic symptom in all three cases

54. The optical axis of the eye (the line from the
center of the cornea to the fovea) points
straight ahead during straight-ahead gaze, but
the axis of the orbit points about 23 degrees
laterally. The superior and inferior recti
originate from the back of the orbit, and so
their direction of pulling is not parallel to the
optical axis. As a result, although the superior
rectus primarily elevates the eye, it also has
smaller adducting and intorting effects.
(Similarly, although not indicated in the Þgure,
the inferior rectus primarily depresses but also
adducts and extorts a little.)

55. The pulling direction of the obliques is not
aligned with either the optical axis or the
orbital axis, and their actions change with the
direction of gaze. The superior oblique inserts
in the posterior half of the eye and pulls
diagonally forward. A, As a result, during
straight-ahead gaze, although it primarily
intorts the eye, it also pulls the back of the eye
a little bit medially and upward (i.e., abducts
and depresses a little). B, During adduction,
the direction of pull is more nearly in line with
the optical axis, and the same muscle
depresses more and intorts less. C, During
abduction, the direction of pull can wind up
perpendicular to the optical axis, and the
action becomes purely intorsion. (Similarly,
although not indicated in the Þgure, the
inferior oblique primarily extorts when the eye
is abducted, but it also elevates and abducts in
other directions of gaze.)