anatomy of orbit

1. Anatomy of eye

2. Outline
• Orbital anatomy
• Orbital adnexa
• The eye globe

3. Outline of anatomy of Orbit
• Orbital volume
• Bony orbit
• Orbital walls
• Orbital foramen
• Orbital fissure
• Peri orbital sinuses
• Blood supply and nerve supply

4. Orbital anatomy
Orbital volume
•The volume of each adult orbit is
slightly less than 30 cm3.
•Pear shaped
•The orbital entrance averages about
35 mm in height and 45 mm in width.
The maximum width is about 1 cm
(behind the anterior orbital margin)
•In adults, the depth of the orbit varies
from 40 to 45 mm from the orbital
entrance to the orbital apex
•Both race and sex affect each of these
measurements.

5. Bony Orbit
• Seven bones make up
the bony orbit:
– Frontal
– Zygomatic
– Maxillary
– Ethmoidal
– Sphenoid
– Lacrimal
– Palatine

6. Orbital margin
• Forms quadrilateral spiral
• Superior margin is formed
by frontal bone
• Medial margin formed by
the frontal bone,posterior
lacrimal crest of the
lacrimal bone and anterior
lacrimal crest of the
lacrimal bone
• Inferior margin is formed by
the maxillary bones and
zygomatic bones
• Lateral margin is formed by
the zygomatic and the
frontal bones

7. Orbital Roof
• The orbital roof is formed
from both the orbital plate
of the frontal bone and the
lesser wing of the
sphenoid bone.
• The anterolateral part of
the roof has a depression
called the fossa for the
lacrimal gland
• The trochlear fossa is
situated at the junction of
roof and the medial wall

8. Orbital roof
• Relations
Above, it is related to frontal lobe cerebrum
and meninges
Below, it is related to frontal nerve,
levator
palpebrae superioris, superior rectus,
superior
oblique, trochlear nerve and lacrimal
gland

9. Orbital roof
Clinical applications
•As the roof is perforated neither by major
nerves nor by blood vessels, it can be easily
nibbled away in transfrontal orbitotomy.
•The roof is reinforced laterally by the greater
wing of sphenoid & anteriorly by superior orbital
margin so the fractures which involve frontal
bone tend to pass towards the medial side.

10. Medial Orbital Wall
• Then medial wall of the orbit
is formed from four bones:
– Frontal process of the
maxillary
– Lacrimal bone
– Orbital plate of the
ethmoidal
– Lesser wing of the sphenoid
• Lacrimal fossa is formed by
the frontal process of
maxillary and the lacrimal
bone.
• Lamina papyracea(paper
thin

11. Medial Orbital Wall
• Relations
Medial to the medial wall lie
anterior ethmoidal air sinuses,
middle meatus of nose, middle
and posterior ethmoidal sinuses
and sphenoidal air sinuses.
The orbital surface of medial wall is
related to superior oblique muscle
and medial rectus muscle. In
between the two muscles lie
anterior ethmoidal nerve, posterior
ethmoidal nerve, infra trochlear
nerve, terminal branch of
ophthalmic artery

12. Medial Orbital Wall
Clinical applications
• It is the thinnest wall of the orbit so it is
frequently fragmented as a result of indirect blow
out fractures.
• This accounts for ethmoiditis being the most
common cause of orbital cellulitis, especially in
children.
•The medial wall is frequently eroded by
inflammatory lesions, cysts and neoplasms

13. Orbital Floor
• The floor of the orbit
is formed from three
bones:
– Maxillary
– Palatine
– Orbital plate of the
zygomatic
• Infraorbital groove
• Inferior oblique
muscle

14. Orbital Floor
• Relations
Below it is related to
maxillary air sinus
Above it is related to
inferior rectus muscle,
inferior oblique muscle and
nerve to inferior oblique.

15. Orbital Floor
Clinical applications
•The orbital floor being quite thin is commonly
involved in ‘blow- out fractures’ due to
unsupported dome of maxillary sinus and plus
the infra orbital groove & canal weaken the
already thin floor further.
•It is easily invaded by tumors of the maxillary
antrum

16. Lateral Orbital Wall
• Thickest and strongest
• Formed from two
bones:
– Zygomatic
– Greater wing of the
sphenoid
• Lateral orbital
tubercle (Whitnall’s
tubercle):
 check ligament of lateral rectus muscle
 Suspensory ligament of eye ball
 Lateral palpebral ligament
 Aponeurosis of the levator muscle
 Whitnall ligament

17. Lateral Orbital Wall
• Relations
Medially it is
related to
lateral rectus,
lacrimal nerve
and vessels and
zygomatic
nerve

18. Lateral Orbital Wall
Clinical applications
•The anterior half of globe is not covered by
bone on lateral side. Hence, palpation of
retrobulbar tumors is easier from the lateral
side.
• It is the strongest portion of the orbit and
needs to be sawed open in lateral orbitotomy.
•The zygomaticosphenoid suture is an important
landmark during surgery.

19. Orbital Foramen
The optic foramen
•Leads from middle cranial fossa to
the apex of orbit.
•6.5mm in diameter
•Lesser wing of sphenoid bone
•Conducts the optic nerve,
opthalmic artery and sympathetic
fibers from the carotid plexus.

20. Optic foramen
Clinical applications
•Optic foramen enlargement is commonly seen
with optic nerve gliomas.
•Blunt trauma may cause optic canal fracture,
haematoma at the orbital apex or shearing at
the nerve of foramen resulting in optic nerve
damage

21. Orbital Foramen
Supraorbital foramen
•Medial third of the
superior margin of orbit
•Blood vessels and supra
orbital nerve
Clinical applications
•The supraorbital nerve
block is often used to
accomplish regional
anesthesia of the face

22. Orbital Foramen
• Anterior ethmoidal
foramen transmits the
anterior ethmoidal
vessel and nerve
• Posterior ethmoidal
foramen transmits the
posterior vessels and
nerve through the
frontal bone

23. Orbital Foramen
• Zygomatic foramen contains
zygomaticofacial and
zygomatico temporal branches
of zygomatic nerve and
zygomatic artery
• The infraorbital foramen
contains the infraorbital
artery, infraorbital vein, and
infraorbital nerve.
• Clinically, the infraorbital
foramen provides a route of
spread for infection or
maxillary tumors to the orbit
and the skull base.

24. Orbital Fissure
Superior orbital fissure
•Located between the
greater and lesser wings of
sphenoid
•22mm long
•Spanned by the common
tendinious ring of the rectus
muscle(annulus of zinn)

25. Superior orbital fissure
• Above the ring, the
superior orbital fissure
transmits the
 lacrimal nerve of CN5
 frontal nerve of CN5
 Trochlear nerve
 superior opthalmic vein
• Within the ring
 superior and inferior division
oculomotor nerve
 nasociliary branch of CN5
 sympathetic roots of ciliary
ganglion
 abducen nerve

26. Clinical applications
• When idiopathic inflammation preferentially
involves the superior orbital fissure, the
Tolosa-Hunt syndrome (painful
ophthalmoplegia) results.

27. Orbital Fissure
Inferior orbital fissure
•lies below the superior
fissure between the lateral
wall and the floor of orbit.
•Transmits the infraorbital
and zygomatic branches of
CN5, an orbital nerve from
the pterygopalatine
ganglion and the inferior
opthalmic vein.

28. Inferior orbital fissure
Clinical applications
•The inferior orbital fissure extends more anteriorly than
the superior orbital fissure, ending about 20 mm from
the anterior orbital rim. This structure serves as a
posterior landmark in the surgical subperiosteal
dissection along the orbital floor.
• Immediately beneath the infraorbital fissure lies the
pterygoid space with the temporalis fossa laterally; blunt
trauma to the temporalis muscle can result in orbital
hemorrhage via this connection

29. Periorbital Sinuses
Frontal sinus
•The frontal sinus lies deep to the
superior orbital rim and drains into the
middle meatus via the frontonasal
duct.
•Each sinus is a single chamber with
intrasinus septae, which give it a
scalloped appearance radiologically.
Clincial application
•The frontal sinus is a common site for
mucocele development which can
extend into the orbit.

30. Periorbital Sinuses
Maxillary sinus
•largest of the sinuses
•the sinus roof is the orbital
floor
Clinical applications
•The maxillary sinus drains into
the middle meatus through an
ostium located near the level of
the orbital floor, thus orbital
tissues that are displaced in
surgery or trauma may obstruct
the ostium.

31. Periorbital Sinuses
Ethmoid and sphenoid sinuses
•The ethmoid sinuses are
shaped like a box slightly wider
posteriorly where it articulates
with the sphenoid
•The medial walls of the orbit,
which borders the nasal wall
anteriorly and ethmoidal sinus
and sphenoid sinus posteriorly
are almost parallel.
.

32. Ethmoid and sphenoid sinus
Clinical applications
•It is important to be aware of the anatomic
relationship of anterior ethmoid air cells to the
lacrimal sac fossa when performing external
dacryocystorhinostomy during creation of
ostium

33. Blood Supply
• Internal carotid artery
• External carotid artery

34. Blood Supply
Opthalmic artery
•arises from the ICA and is
the major blood supply of
the orbit
•Orbital group
•Ocular group
Long ciliary artery
Short ciliary artery
Anterior ciliary artery
Central retinal artery
Muscular artery

35. Blood Supply
Lacrimal artery
•irrigate the upper and lower eyelids and the
conjunctiva, superior and lateral recti muscles
and lacrimal gland.
Supraorbital artery
•It supply the eyebrow and the forehead. Within
the orbit, the supraorbital artery supplies the
superior rectus muscle and the levator palpebral
muscle.
Ethmoidal artery
•It supplies the ethmoidal cells,superior oblique
muscle, the superior and medial recti muscles,
and the superior levator palpebral muscle.
Frontal artery
•supplies the forehead and the scalp.
Dorsal nasal artery
Internal palpebral artery

36. Blood Supply
Venous Blood supply
Vortex veins
•The vortex veins provide drainage
for the uveal tract (choroid, ciliary
body, iris) and drain into superior
and inferior opthalmic veins
Superior ophthalmic vein
•The superior ophthalmic vein is the
main venous channel for the
superior orbit.it drains to the
cavernous sinus.
Inferior ophthalmic vein
•The inferior ophthalmic vein
provides a channel for inferior
drainage.
.

37. Blood supply
Clinical applications
•In cases of severe orbital infection, the
valveless venous system allows spread of
infected emboli to the cavernous sinus and can
cause cavernous sinus thrombosis

38. Innervation of the Orbit
• The innervation of the orbit
can be divided into 4
functional components:
 general somatic efferent
 general somatic afferent
 general visceral efferent
 special sensory afferent
• The general somatic
efferents include the motor
division of the oculomotor
nerve (CN III), the trochlear
nerve (CN IV), and the
abducens nerve (CN VI).

39. Innervation of the Orbit
Oculomotor nerve
•The oculomotor nerve supplies the
superior rectus muscle and the levator
palpebrae superioris, medial rectus,
inferior rectus, and inferior oblique.
Trochlear nerve
•The trochlear nerve innervates the
superior oblique muscle.
Abducens nerve
•The abducens nerve innervates the
lateral rectus.
•The relatively long intracranial course of
the abducens nerve makes it susceptible
to injury secondary to trauma, tumor,
aneurysm, and infection.
.

40. Innervation of the orbit
Trigeminal nerve
•The trigeminal nerve, supplies the general sensory
innervation to the orbit
•the oculocardiac reflex is triggered by afferent
fibers of the trigeminal nerve, which synapse with
visceral motor nucleus neurons of the vagal nerve
in the reticular formation of the brainstem. It
causes bradycardia, hypotension, and nausea when
pressure is applied to the globe or when the
extraocular muscles are stretched

41. Innervation of the Orbit
Ophthalmic and other nerves
•Within the orbit, the ophthalmic nerve branches
into the lacrimal, frontal, and nasociliary nerves.
•The lacrimal nerve innervates the lacrimal gland
•The frontal branch innervate the eyebrow and
scalp.
•The nasociliary branch enters the orbit through
the annulus of Zinn and then gives off short and
long ciliary nerves to the globe.
•The long ciliary nerves are responsible for
dilatation of the pupil.
• The infratrochlear nerve is also a branch of the
nasociliary nerve and provides sensory
innervation to the medial lower lid, side of nose,
conjunctiva, and lacrimal sac.

42. Thank you

43. References
• Fundamentals and principles of ophthalmology(2012-2013)-
American Academy of ophthalmology
• Clinical Anatomy of Orbit and Common Orbital Disease-
Dr.M.Kokilam, MS Resident, Aravind Eye Hospital, Madurai
• Orbit anatomy http://
emedicine.medscape.com/article/835021-overview
• Duane’s Clinical ophthalmology Chapter 21
Orbital Anatomy and Its Clinical Applications
Deborah D. Sherman, Cat N. Burkat and Bradley N. Lemke
• Anatomy of The Bony Orbit-Some Applied Aspects
Patnaik V.V.G., 2Bala Sanju, 3Singla Rajan K.
Department of Anatomy, Government Medical College, Patiala.
Amritsar. Department of Oral & Maxillofacial Surgery, SGRD
Institute of Dental Sciences & Research, Amritsar.