This document discusses the anatomy of the bony orbit and extraocular muscles. It describes the seven bones that make up the bony orbit, including the frontal, zygomatic, maxillary, ethmoidal, sphenoid, lacrimal and palatine bones. It details the structures and openings of the orbital roof, floor, medial wall and lateral wall. It then discusses the six extraocular muscles - the four rectus muscles (superior, inferior, medial and lateral), and two oblique muscles (superior and inferior). It outlines the origin, insertion, nerve supply and actions of each muscle. Finally, it discusses clinical implications such as causes of strabismus and Horner's syndrome.

1. DR. SUSHRUT AHALE
ORBIT AND
EXTAOCULAR MUSCLES

2. Bony Orbit
Seven bones make up
the bony orbit:
 Frontal
 Zygomatic
 Maxillary
 Ethmoidal
 Sphenoid
 Lacrimal
 Palatine

3. Bony Orbit
ROOF:
The orbital roof formed
from both the orbital plate
of the frontal bone and the
lesser wing of the sphenoid
bone. Above the roof is
cranial cavity.
Contains: Lacrimal fossa
for lacrimal gland
FLOOR:
The floor of the orbit is
formed from three bones
and related to maxillary
sinus:
 Maxillary
 Palatine
 Orbital plate of the
zygomatic
It contains:
Infraorbital groove
Attachment of Inferior
Oblique muscle

4. Bony Orbit
MEDIAL WALL of the
orbit is formed from four
bones and related to lateral
wall of nose:
 Frontal process of the
maxillary
 Lacrimal
 Orbital plate of the ethmoidal
 Lesser wing of the sphenoid
Lacrimal fossa for lacrimal
sac.
LATERAL WALL
Formed from two bones:
 Zygomatic
 Greater wing of the sphenoid
Thickest and strongest
Lateral orbital tubercle
(Whitnall’s tubercle) for
attachment of lateral
check ligament

5. Orbital Foramina
 The optic foramen: Transmit
Optic nerve and Ophthalmic
artery
 The supraorbital foramen, or
notch: transmit supraorbital
nerve and vessels
 The zygomatic foramen:
Transmit Zygomatic nerve
 Infraorbital canal: Transmit
Infraorbital nerve and vessels
 Superior orbital fissure:
Transmit occulomotor nerve,
trochlear nerve, abducent nerve,
Branches of Ophthalmic nerve,
Ophthalmic veins
 Inferior orbital fissure:
Maxillary nerve

6. Structures passing through Superior
orbital fissure

7. Extraocular Muscles
in the orbit

8. Extraocular Muscles
The four recti and
two oblique muscles
All are supplied by
oculomotor nerve III
except superior
oblique (Trochlear
N) and lateral rectus
(Abducent N)

9. Voluntary Muscles:
1. Four Recti – Superior, Inferior, Medial and Lateral
2. Two Obliques – Superior & Inferior
3. Elevator of upper eyelid – Levator palpebrae
superioris.
Involuntary Muscles:
1. Superior tarsal muscle – Deeper part of levator
palpebrae superioris
2. Inferior tarsal muscle
3. Orbicularis muscle
Extraocular Muscles

10. Extraocular Muscles

11. Extraocular Muscles: Origin
4 Recti originate from a common tendinous ring (the
annulus of Zinn) which is attached at the apex of the
orbit encircling the optic foramina and the medial
part of the superior orbital fissure.
SO: arises from the body of sphenoid bone above and
medial to the optic foramen
IO: arises by a round tendon from a shallow
depression on the orbital plate of maxilla

12. Extraocular Muscles: Origin
Common annular tendinous ring

13. Extraocular Muscles: Origin
Superior ObliqueLevator palpebrae superioris
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior Rectus
Inferior Oblique

14. Extraocular Muscles
Insertion: on the sclera
Recti – on sclera in front of
equator;
distance from cornea –
SR = 7.7mm, LR = 6.9mm, IR = 6.5mm,
MR = 5.5mm.
Superior Oblique – Behind the
equator on sclera in superolateral
posterior quadrant, between the
superior and lateral recti.
Inferior Oblique – Behind the
equator on sclera in inferolateral
posterior quadrant, between the recti
superior and lateralis.

15. Blood Supply:
2 muscular arteries from the ophthalmic artery
The medial (larger) branch supplies the MR, IR and
IO muscles.
The lateral (smaller) branch supplies the LR, SR, SO
and levator palpebrae muscles.
Anterior ciliary arteries (usually 7) from the above
arteries.
Veins correspond to the arteries and empty into the
superior and inferior ophthalmic veins.

16. Nerve Supply:
 Superior, Inferior & Medial Recti; Levator
palpebrae superioris and Inferior Oblique
Muscles are supplied by Oculomotor (III cranial)
Nerve

17. Nerve Supply:
Trochlear (IV cranial) nerve supplies
Superior Oblique [SO4]

18. Nerve Supply:
Abducent (VI cranial) nerve supplies
Lateral Rectus [LR6]

19. Levator Palpebrae Superioris:
 Origin: Orbital surface of lesser wing of
sphenoid bone, anterosuperior to optic canal.
 Insertion: Splits into two laminas
 Superior lamina (voluntary) to the skin of upper
eyelid & anterior surface of superior tarsal
plate
 Inferior lamina (Muller’s muscle) (involuntary)
to the upper margin of superior tarsus
(superior tarsal or muller’s muscle) & superior
conjunctival fornix
 Nerve Supply: Oculomotor nerve (voluntary
part); Sympathetic (involuntary part, ie Muller’s
muscle)
 Action: Elevation of upper eyelid.
 Damage to oculomotor nerve leads to
paralysis of this muscle and leads to ptosis.
 Even damage to sympathetic fibers in Horner’s
syndrome leads to partial ptosis due to
paralysis of Muller’s muscle.

20. Movements of Eyeball:
 Along vertical axis : Lateral rotation (Abduction) & Medial rotation
(Adduction)
 Along Transverse axis: Elevation & Depression
 Along anteroposterior axis: Intortion (cornea moves medially
from 12 O'clock position) & Extortion (cornea moves laterally from 12
O'clock position)

21. Actions of Recti Muscles:

22. Actions of Recti Muscles:
Superior rectus:
Elevation, Adduction, Intortion
Inferior rectus:
Depression, Adduction, Extortion
Medial rectus:
Adduction
Lateral rectus:
Abduction

23. Actions of Oblique Muscles:
Superior Oblique:
Depression,
Abduction,
Intortion
Inferior Oblique:
Elevation,
Abduction,
Extortion
Both the obliques are attached behind the equator and thus,
cause opposite movement of the eyeball in the vertical axis.

24. Actions of Oblique Muscles:
Superior Oblique: :
Intortion
Inferior Oblique :
Extortion
Anteroposterior axis

25. Actions of Oblique Muscles:
Both oblique muscles
pull the posterolateral
quadrant
anteromedially; thus,
abduct the eyeball.
Vertical axis

26. Extraocular muscles actions:

28. Movements of Eyeball:
MUSCLE NERVE
SUPPLY
ACTIONS
SUPERIOR
RECTUS
Oculomotor Adduction, Elevation,
Intorsion
SIN
INFERIOR
RECTUS
Oculomotor Adduction, Depression,
Extorsion
RAD
MEDIAL
RECTUS
Oculomotor Adduction
RAD
LATERAL
RECTUS
Abducent LR6 Abduction
SUPERIOR
OBLIQUE
Trochlear SO4 Abduction, Depression,
Intorsion
SIN
INFERIOR
OBLIQUE
Oculomotor Abduction, Elevation,
Extorsion

29. Applied Anatomy:
 Abnormal deviation of the is known as Squint
(Strabismus).
 Paralysis of Lateral Rectus due to damage to
Abducent nerve leads to Medial Squint.
 Damage to Oculomotor nerve (3Ds) leads
to paralysis of all muscles of eye except Superior
Oblique and Lateral Rectus leading to Divergent
Squint, Diplopia and Ptosis- Drooping of
Eyelid.
 Damage to Trochlear nerve cause paralysis
of Superior Oblique muscle causing diplopia
while looking downwards.
Medial Squint
Divergent Squint and
Ptosis -Drooping of
Eyelid.

30. Superior Oblique
Inferior Oblique
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus

31. • Causes: Interruption of sympathetic pathway like multiple sclerosis,
syringomyelia, traction of stellate ganglion by cervical rib, ganglion
metastatic lesion.
• Signs:
• Constriction of pupil (miosis) due to paralysis of dilator pupillae
• Slight drooping of eyelid (ptosis) due to paralysis of Muller’s muscle
(Part of Levator palpebrae superioris)
• Enophthalmos (Retraction of eyeball) due to paralysis of
Orbicularis muscle which supports the eyeball
• Loss of sweating (anhydrosis) due to damage to sympathetic fibers
to the sweat glands
• Loss of ciliospinal reflex
Horner’s syndrome