you can get information about the extraocular muscles which are responsible for the movement of the eyes in different direction, near and distance. you will know how many extraocular muscles and how they work.... you will get information about the different position of gazes....

2. EXTRA
OCULAR
MUSCLES
(EOM)
By
Anam Sehreen
Doctor of Optometry

3. Extraocular Muscles
 The eyeballs are moved by 6 extrinsic muscles, attached
at one end to the eyeball and at the other to the walls
of the orbital cavity. There are 4 straight and 2 oblique
muscles.
 Movement of the eyes to look in a particular direction is
under voluntary control but co-ordination of movement
needed for convergence and accommodation to near
or distant vision, is under autonomic control.
Purpose: To control the movement of the globe

5. Anatomical Arrangement
All of the extraocular muscles form a “cone within
the bony orbit with the exception of the inferior oblique.
This conic structure is known as the “annulus of Zinn.”

6. Blood Supply
The eye's major blood supply comes from the
ophthalmic artery.
 The lateral muscular branch of ophthalmic
artery supplies the lateral rectus, superior
rectus, and superior oblique muscles.
 The medial muscular branch supplies the
inferior rectus, medial rectus, and inferior
oblique muscles.

7. EOM Innervations
Each EOM is innervated by a specific cranial nerve (CN):
 Medial rectus (MR): CN III
 Lateral rectus (ER): CN VI
 Superior rectus (SR): CN III
 Inferior rectus (IR): CN III
 Superior oblique (SO): CN IV
 Inferior oblique (IO): CN III
SO4 (LR6) 3

8. EOM
 Origin
 Course
 Insertion
 Action

9. Muscle
Length
of active
muscle
(mm)
Origin Anatomic
insertion
Direction
of pull
Innervation
Medial
Rectus
40 Annulus
of Zinn
5.5 mm from
Medical limbus
90o Lower
CN III
Lateral
Rectus
40 Annulus
of Zinn
6.9 mm from
Lateral limbus
90o CN VI
Superior
Rectus
40 Annulus
of Zinn
7.7 mm from
Superior limbus
23o Upper
CN III
Inferior
Rectus
40 Annulus
of Zinn
6.5 mm from
Inferior limbus
23o Lower
CN III
Superior
Oblique
32 Orbital apex
above
annulus of
Zinn
Posterior to
Equator in
Supero-temporal
Quadrant
51o CN IV
Inferior
Oblique
37 Behind
lacrimal
fossa
Muscular area 51o Lower
CN III

10. Medial Rectus
Main Action:
Adduction
Innervation:
Inferior Division of
Oculomotor Nerve
C
Temporal Nasal
C

11. Lateral Rectus
Main Action:
Abduction
Innervation:
Abducens
C
Temporal Nasal
C

12. Temporal Nasal
C
23°
Superior Rectus
Main Action:
Supraduction
Secondary Action:
Incycloduction adduction
Innervation:
Sup. Division of Oculomotor
Nerve (i.e. III Cranial Nerve)

13. Superior Rectus Actions

14. Inferior Rectus
Main Action:
Infraduction
Secondary Action:
Excycloduction Adduction
Innervation:
Inferior Division of
Oculomotor Nerve
Temporal Nasal
C
23°

15. Superior Oblique
Main Action:
Incycloduction
Secondary Action:
Infraduction abduction
Innervation:
Trochlear Nerve
C
Temporal Nasal
C
51°

16. Superior Oblique Actions

17. Inferior Oblique
Main Action:
Excycloduction
Secondary Action:
Supraduction Abduction
Innervation:
Inferior Division of
Oculomotor Nerve
C
Temporal Nasal
C
51°

18. Inferior Oblique Actions

20. A way to remember
All obliques Abduct
All Recti Adduct except LR
All superior muscles Intort
All inferior muscles Extort

21. Ocular Movements

22. As the eye turns around the vertical axis,(Z)
the visual axis sweeps along the horizontal plane.

23. As the eye turns around the horizontal axis, (X)
the visual axis sweeps along the vertical plane.

24. Intortion and extortion refer to rotation around the
visual axis, Y-axis
 Intortion refers to a nasal rotation from the 12 o'clock
position.
 Extortion refers to a temporal rotation from the 12
o'clock position.

25. Nine Position Of Gaze

26. R L
RLR
LMR
RMR
LLR
RSR
LIO
RIO
LSR
RIR
LSO
RSO
LIR
The Diagnostic Positions of Gaze

27. Ocular movements
 Agonist-Antagonist:
Muscles of the same eye that move the eye in
opposite directions.
1. The Agonist is the primary muscle moving the eye in
a given direction.
2. The Antagonist acts in the opposite direction to the
agonist.
e.g. Rt- LR and Rt- MR

28. 3. Synergist:
Muscles of the same eye that move the eye in the same
direction.
e.g. Rt-SR and Rt-IO acts synergistically in elevation.
4. Yoke Muscles:
Pairs of muscles, one in each eye, that produce
conjugate ocular movements.
Ocular movements

29. RSR
LIO
RIO
LSR
RIR
LSO
RSO
LIR
RLR
LMR
RMR
LLR
Yoke Muscles
R L
 Medial Rectus Lateral Rectus
 Lateral Rectus Medial Rectus
 Superior Rectus Inferior Oblique
 Superior Oblique Inferior Rectus
 Inferior Oblique Superior Rectus

30.  Ductions
 Versions
 Vergences
Ocular movements

31. Definition:
monocular eye movements around the axis of Fick,
consisting:
 Adduction
 Abduction
 Elevation
 Depression
 Torsion
Ductions

32. Versions
Definition:
These are binocular, simultaneous, conjugate movements.
e.g. Positions of gaze
Vergences
Definition:
These are binocular, simultaneous, disjugate movements.
e.g.
Convergence
Divergence
Versions and Vergences

33.  Clinical orthoptics(Fiona J. Rowe)
 Diagnosis and management of ocular motility (Alec
M. Ansons and Helen Davis)
References

34. 1. All EOMS form a cone within the bony orbit except:
a) Inferior oblique
b) Superior oblique
c) Superior rectus
d) inferior rectus
2. Secondary angle of deviation will be:
a) Smaller than primary angle of deviation
b) Greater than primary angle of deviation
c) Equal to primary angle of deviation
d) None of the above
MCQs

35. 3. Versions are:
a) Binocular, simultaneous, disjugate eye movements
b) Uniocular, simultaneous, disjugate eye movements
c) Binocular, simultaneous, conjugate eye movements
4. Superior oblique is supplied by:
a) Third nerve
b) Fourth nerve
c) Sixth nerve
5. Length of superior oblique muscle:
a) 42 mm
b) 40mm
c) 32mm