The document describes the anatomy of the bony orbit and the extraocular muscles within. It discusses the seven bones that make up the bony orbit, including the frontal, zygomatic, maxillary, ethmoid, sphenoid, lacrimal and palatine bones. It describes the roof, floor, medial wall and lateral wall of the orbit. It then discusses the extraocular muscles, including the four rectus muscles, two oblique muscles and levator palpebrae superioris. It details the origin, insertion, nerve supply and actions of each muscle. Finally, it discusses some clinical implications like strabismus and Horner's syndrome.

1. ORBIT
EXTRAOCCULAR MUSCLES
Dr.B.B.Gosai

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

3. Bony Orbit
ROOF:
FLOOR:
The orbital roof formed
The floor of the orbit
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
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. Extra ocular 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. Extra ocular Muscles in the Orbit
Voluntary Muscles:
1. Four Recti – Superior, inferior, medial and lateral.
2. Two Oblique – 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. Orbitalis muscle

10. Extra ocular Muscles

11. Extra ocular Muscles:Origin
Common annular tendinous ring

12. Extra ocular Muscles:Origin
Levator palpebrae superioris
Superior Oblique
Superior Rectus
Lateral Rectus
Medial Rectus
Inferior Rectus
Inferior Oblique

13. Levator Palpebrae Superioris








Origin: Orbital surface of lesser wing of
sphenoid bone, anterosuperior to optic
canal.
Insertion: Splits in two lamina
Superior lamina (voluntary) to Skin of
upper eyelid & anterior surface of
superior tarsal plate
Inferior lamina (Muller’s muscle)
(involuntary) to upper margin of superior
tarsus (superior tarsal or muller’s muscle)
& superior conjunctival fornix
Nerve Supply : Oculomotor nerve
(voluntary part); Sympathetic (involuntary
part)
Action: Elevation of upper eyelid.
Damage to oculomotor nerve lead 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.

14. Extra ocular 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 recti superior and lateralis.
Inferior Oblique : - Behind the equator on sclera in inferolateral
posterior quadrant, between the recti superior and lateralis.

15. Nerve Supply:
Abducent (VI cranial) nerve supplies
lateral rectus

16. Nerve Supply:
Trochlear (IV cranial) nerve supplies
superior oblique

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

18. 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)

19. Actions of Recti Muscles

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

21. Actions of Oblique Muscles
Superior Oblique: :
Depression,
Abduction,
Intortion
Inferior Oblique :
Elevation,
Abduction,
Extortion

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

23. Actions of Oblique Muscles
Vertical axis
Both oblique muscles pulls
posterolateral quadrant
anteromedially; thus abduct
the eyeball.

25. Movements of Eyeball
Recti muscles: straight muscles
•Superior rectus: oculomotor nerve
•Adduction, elevation, intorsion
•Inferior rectus: oculomotor nerve
•Adduction, depression, extorsion
•Medial rectus: oculomotor nerve
•Adduction
•Lateral rectus: abducent nerve
•Abduction
•Superior oblique: trochlear nerve
•Abduction, depression, intorsion
•Inferior oblique: oculomotor nerve
•Abduction, elevation, extorsion

26. Applied Anatomy
 Abnormal deviation of eyeball is known as
Squint (Strabismus).
 Paralysis of Lateral rectus due to damage to
Abducent nerve leads to Medial Squint.
Medial Squint
 Damage to Occulomotor nerve leads to
paralysis of all muscles of eye except Superior
oblique and lateral rectus leading to Lateral
Squint and Ptosis-Dropping of Eyelid.
 Damage to Trochlear nerve cause
paralysis of superior oblique muscle causing
diplopia while looking downwards.
Lateral Squint and
Ptosis -Dropping of
Eyelid.

27. Inferior Oblique
Superior Oblique
Lateral rectus
Medial rectus
Superior rectus
Inferior rectus

28. Horner’s syndrome
• 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 Orbitalis
muscle which support the eyeball
•
Loss of sweating (anhydrosis) damage to sympathetic fibers to
sweat glands
•
Loss of ciliospinal reflex