MD

1. The Orbital cavity
Prepared by : Waqar Qabba’a
Supervised by Dr.Wafa’ Sakaji
Department of ophthalmology

2. Function
What is the function of the Orbit ?
The orbit holds the eye in the correct
position.
The orbit also protects the eye because
the bones surrounding the eye “stick
out” further than the eye, objects tend
to hit the orbit and not the eye.

3. Introduction
• The orbital cavities :
a pair of large bony sockets that contain:
the eyeballs, their associated muscles, nerves,
vessels, and fat, and most of the lacrimal apparatus.
• Each one is pear shaped ,and its apex is directed
posteriorly ,medially ,and slightly upward.
• The medial wall runs antero-posteriorly parallel to
sagittal plane ,the lateral wall diverges at angle of about
45degrees
• The orbit forms from seven bones :
(maxilla ,palatine ,zygomatic , sphenoid ,frontal ,
ethmoid ,and lacrimal ).

6. Walls of cavity Lined with periosteum , apex at the medial end of
superior orbital fissure

7. Walls of the orbital cavity
• Roof :
• Formed by the orbital plate of frontal bone and to a small
extent of lesser wing of sphenoid posteriorly.concave
• Anterolaterally there is slight depression ( lacrimal fosse) for
orbital part of lacrimal gland .
• Anteriomedially the roof is invaded by fronat air sinuses
• The Roof is thin and fragile and in old age portions of roof
may be absorbed so it may be Easily fx
• The Roof separates orbital cavity from anterior crainal fossa
and frontal lobe.

8. •Floor :
• Formed largely by orbital plate of maxilla , orbital
surface of zygomatic ,small orbital process of
palatine.
• Separate the orbital cavity from maxillary sinus.
• Floor is continuous with lateral wall anteriorly, but
seperated posteriorly by inferior orbital fissure .
• Ifr orb fiss__forward infraorb groove –canal --
foramen at face
• Commonly involved in BLOW OUT FRACTURES
• Easily invaded by tumors of the maxillary antrum

10. • Lateral wall :
• Is the thickest wall.
• anterior 1/3 is formed by zygomatic bone.
• posterior 2/3 is formed by greater wing of sphenoid.
• it is continuous with roof anteriorly but seperated
posteriorly by superior orbital fissure which communicate
with middle cranial fossa .
• On the anterior part of the wall,there is a prominence
the marginal tubercle of whitnall.It give attachment to
the check ligament of the lateral rectus muscle and to the
suspensory ligament of the eyeball and lateral palpepral
ligament

12. Medial wall
•Thinnest orbital wall:0.2-0.4mm thick
•Majority of it is formed by Lamina papyracea
Formed by four bone from anterior to posterior :
1. frontal process of maxilla,
2. lacrimal bone,
3.Orbital plate of ethmoid ,largest part
4.body of sphenoid.
Lacrimal groove: on anterior part of medial wall ,for lacrimal
sac , formed by lacrimal bone posterior ,frontal process of maxilla
anterior,bounded by lacrimal crests, continuous below with
nasolacrimal canal.

14. Lacrimal Groove

16. 1. Since it is the thinnest,ethmoiditis is the commonest cause o
f orbital cellulitis, especially in children.
2. Frequently eroded by chronic inflammatory lesions, neoplas
ms,cysts.
3. It is easily fractured during trauma.
4. Hemorrhage can occur due to trauma to the ethmoidal
vessels.

17. Relations of the bony orbit :
• Superior
anteromedially : frontal air sinus.
anterior cranial fossa .
• inferior
maxillary air sinus
• Lateral
anteriorly : temperal fossa.
posteriorly :middle cranial fossa.
• Medially
nasal cavity ,ethmoidal sinus , sphenoid sinus.

18. Orbital openings

21. Superior orbital fissure
 Between lesser and greater wings of sphenoid
,roof & lateral wall
 Connect middle cranial fossa with cavity
 Widest part at medial end
 Midway on lower edge – small,sharp spine for
lateral rectus
 Content pass : occulomotor, trochlear abducent
,opthalmic n and vein ,sympathtic nerve plexus
,recurrent branch of lacrimal art, Orbital branch of
middle meningeal art

22. Inferior orbital fissure
 Between greater wing of sphenoid and maxilla
 Connect pterygopalatine & infratemporal fossae
with the cavity
 Closed by periorbita and m of muller
 Content :maxillary n ( infraorbital) ,zygomatic n ,
branch of pterygopalatine ganglion,,inf opthamic
vein

24. • Optic canal:
1.lies in the lesser wing of sphenoid.
2.is situated close to the apex of the orbit.
3.Measuring 4 to 10 mm long.
4.It connects the orbit to the middle cranial fossa .
5.related medially to body of sphenoid.
6. transmit optic nerve, ophthalmic artery with its
surrounding sympathetic plexus .

26. • Ethmoidal foramina:
1. lies in frontoethmoidal suture or in frontal bone.
2. anterior foramen open in anterior cranial fossa at lateral edge ocribriform
plate transmit anterior ethmoidal artery and nerve
3. posterior foramen traverse ethmoidal bone , transmit posterior
ethmoidal artery and nerve.
.

27. • Zygomaticofacial and zygomaticotemperal foramen:
1. lies on the lateral wall of orbit.
2. Zygomaticofacial foramen transmit Zygomaticofacial nerve.
3. zygomaticotemperal foramen transmit zygomaticotemperal nerve.

28. Orbital periosteum
( orbital fascia)
• Is the periosteum of the bone that form the wall of orbit,
loosely attached to bone .
• At orbital margin, the periorbita is continuous with
periosteum on external surface of skull, give attachment to
the orbital septum.
• At lacrimal groove it splits to enclose lacrimal sac and
continue inferior to form periosteum of nasolacrimal canal.

30. • Posteriorly, around optic canal and medial end of superior
orbital fissure, it thickens to form a fibrous ring (common tendinous ring).
• Periorbita receive its sensory innervations from branch of
trigeminal nerve.

31. Orbital muscle (Muscle of
Muller)

32. • Is a thin layer of smooth muscle that bridge
the inferior orbital fissure .
• Its embedded in the fascia of periorbita
• Nerve supply : sympathetic nerves
• Apart from its possible effect on the position of the
eyeball in the orbit, the muscle seems to be mainly concerned
with directing facial venous blood to or away from the
cavernous sinus which acts as a heat exchanger for internal
carotid blood.

33. Effect of age on orbital
cavity
 At birth : Relatively large and ossified margins .
- Protect the eye during parturition
 Young children :
1. Look more laterally than adult
2. Superior & inferior orbital fissure are wider, become
narrowed by growth of greater wing of sphenoid.
3. Distance between the orbit are small and increases
by growth of frontal& ethmoidal sinuses
 Old age :
Bony absorption >>> holes in roof , med & lat walls.

34. Thank you 