The document summarizes the anatomy of the orbit, including its development, shape, dimensions, walls, contents, and openings. It describes the bones that form each wall (roof, floor, lateral, medial), as well as the structures and spaces within the orbit. Key points include that the orbit develops from mesenchyme surrounding the optic vesicle, has a quadrangular pyramid shape, and contains the eyeball, extraocular muscles, nerves and vessels. The walls transmit structures through openings like the superior orbital fissure.

1. Dr.A.G.Malavika
Dept of Ophthalmology
TVMCH
PRESENTATION LAYOUT
Development of orbit
Shape and Dimensions
Walls of Orbit

2. Contents of orbit
Orbital apex
Openings of orbit.
DEVELOPMENT OF ORBIT
• Bony orbit is formed from the mesenchyme that encircles the optic
vesicle
• Orbital bones: 6th to 7th week of gestation (starts with maxilla
)
• During this time optic vesicle rotates 170 degree anteriorly.

3. •Orbital walls : derived from neural crest cells which expand to form
1.Frontonasal process
2.Maxillary process.
• Capsule of forebrain forms the orbital roof.

4. SHAPE AND DIMENSIONS
Quadrangular truncated pyramids.
Depth – 42mm (medial wall) , 50mm (lateral wall)
Base – 40mm in width and 35mm in height
Intraobital width – 25mm
Extraorbital width – 100mm
Orbital index : ht/width *100
Megasenes : >89 (eg : Asians )
Mesosenes : 83-89 (eg : Caucasians)
Microsenes : <83 (eg : Blacks)
Vol of each orbit :30cc

5. Vol of orbit : eyeball = 4.5:1

6. Bones forming orbit are
 Frontal
 Ethmoid 
 Palatine
 Maxilla
 Zygomatic
 Sphenoid
Lacrimal

7. CONTENTS OF ORBIT
1.Eyeball
2.Muscles : 4 recti muscles,2 obliques ,Mullers
muscles,LPS
3.Vessels :ophthalmic artery,sup and inf ophthalmic veins, and lymphatics
4.Nerves : CN 2,3,4 nerves :branches of ophthalmic and maxillary
nerves and sympathetic nerves.
5.Lacrimal gland.
6.Orbital fat & orbital fascia.

8. ROOF
W
ALFLOOR
LSMEDIAL
WALL
LATERAL WA
4

9. WALLS OF ORBIT
Roof of orbit
•Triangular in shape
•Formed by orbital plate of frontal bone & lesser wing of sphenoid at the apex
of roof
•Relations : superiorly roof separates the orbit from the frontal lobe of brain.
anterolaterally is the lacrimal fossa containing the lacrimal gland
anteromedially is the trochlear fossa giving attachment to the
fibrous pulley for the tendon of SOM.
•Apex of roof formed by lesser wing sphenoid has the optic foramen.(optic nerve
and ophthalmic artery).

10. •Roof of orbit is separated from its lateral wall by superior orbital fissure through
which orbit communicates with middle cranial fossa.
CLINICAL SIGNIFICANCE
Thin and fragile
Easily fractured by direct violence
(penetrating orbital injuries)
Frontal lobe injury

11. - Laterally – greater wing of sphenoid
-Anteriorly – superior orbital margin
So fracture tend to pass towards medial side
At junction of the roof and medial wall ,the suture line lies in
proximity to cribifrom plate of ethmoid.
rupture of duramater
CSF escapes into orbit or nose.

12. CLINICAL IMPORTANCE
Transfrontal craniotomy : roof is nibbled away easily since it is not
perforated by any major nerves or blood vessels.
• Orbital roof anomaly.
•Deficient orbital roof will result in CSF
pulsation pulsatile
exophthalmos.
FLOOR OF ORBIT
Shortest orbital wall
Roundly triangular

13. Anteromedially : orbital plate of the maxillary
bone.
Anterolaterally : orbital process of the
zygomatic bone.
Posteriorly : superior plate of the palatine
bone.
The floor separates the orbit from the maxillary
sinus.
• The infraorbital canal runs in posteroanterior
direction and exits as infraorbital

14. foramen,located 5mm below the inferior orbital rim,at the level of
anterior portion of pyramidal maxillary process.
• Its contents are infraorbital nerve and vessels.
• LANDMARKS
•At the junction of the anterior part of the floor and medial wall is the
fossa for lacrimal sac.
• Between the floor and lateral wall is the inferior orbital fissure..
Infraorbital
groove
Infraorbital
canal
Infraorbital
foramen

15. CLINICAL SIGNIFICANCE
Blow out fractures :
most common fracture of the orbit fractures of the
orbital floor infraorbital nerves and vessels are
almost invariably
involved.
causes the entrapment of the inferior rectus muscle results
in tear drop sign on CT scan.
 Patient presents with
Diplopia

16. Restricted movements (upgaze)
Paresthesia
Enophthalmos

18. LATERAL WALL
It is the thickest and strongest of all walls
of orbit.
Formed by greater wing of
sphenoid(posteriorly)
Orbital surface of zygomatic bone
(anteriorly)
Relations :
Laterally is the temporal fossa through which passes the tendon of
temporalis muscles.

19. SOF occupies the posterior part
Foramen of zygomatic nerve is in zygomatic bone.
Whitnalls or zygomatic tubercle is a palpable
elevation on zygomatic bone just within the orbital
margin.
LANDMARKS
 LATERAL ORBITAL TUBERCLE OF WHITNALL :
4-5mm behind the lateral orbital rim.
11mm inferior to the frontozygomatic suture
line.
 Gives attachemnet to :
Check ligament of lateral rectus

20. Lockwoods ligament Lateral canthal tendon
the aponeuorosis of levator palpebrae superioris
Orbital septum
Lacrimal fascia
CLINICAL SIGNIFICANCE
• In resection of maxilla,the whitnalls tubercle is spared,otherwise

21. Damage to Lockwood’s
ligament
Inferior dystopia of eyeball
Diplopia

22. MEDIAL WALL
Also k/a nasal wall. Thinnest wall.
Formed by 1.frontal process of maxilla
2.lacrimal bone
3.orbital plate of ethmoid
4.anterior part of lateral surface of body of sphenoid.

23. Between the medial wall and roof are the anterior and posterior
ethmoidal formina.
The anterior medial wall contains the lacrimal canal,bounded
anteriorly by the anterior lacrimal crest and posteriorly by
posterior lacrimal crest.
24-12-6” rule applies to this wall.
Its refers to the distance between the anterior lacrimal crest
and the anterior ethmoidal foramen (24mm).

24. The distance between the anterior ethmoidal
foramen and posterior ethmoidal formen (12mm)
And from this foramen to the optic canal (6mm).
This rule is significant in surgical purposes mainly in orbital decompression

25. OPENINGS IN
ORBITAL CAVITY
oSuperior orbital fissure oInferior
orbital fissure oOptic canal
oNasolacrimal canal oSupraorbital
foramen oInfraorbital foramen

26. SUPERIOR ORBITAL FISSURE
Also known as sphenoidal fissure

27. Comma shaped gap between the roof and
lateral wall
22mm long
 Largest communication between the
orbit and middle cranial fossa.
SUPERIOR ORBITAL
FISSURE
It is divided into 3 parts by common
tendinous ring Structures transmitted through the fissure are :
A) Upper part and lateral part (medial to lateral) :

28. Trochlear nerve.
Frontal nerve.
Lacrimal nerve.
Superior ophthalmic vein.
B) Middle part (within the tendinous ring) :
2 divisions of oculomotor nerve (sup and inf)
Abducent nerve
Nasociliary nerve.

29. C)Lower and medial parts transmits inferior ophthalmic vein.
LANDMARK
Annulus of Zinn
- Spans both superior orbital fissure and optic canal.
- gives origin to four recti muscles .
CLINICAL SIGNIFICANCE
Inflammation of the SOF and apex may result in multitude of signs
including ophthalmoplegia and venous outflow obstruction

30. TOLOSA HUNT SYNDROME

31. SUPERIOR ORBITAL
SYNDROME

32. Fracture at Superior orbital fissure
Involvement of cranial nerves

33. INFERIOR ORBITAL FISSURE
 Also known as sphenomaxillary fissure.
Lies between lateral wall and floor of orbit,giving access to the
pterygopalatine and inferotemporal fossae. It transmits following
1. infraorbital and zygomatic branches of the maxillary division of the
of Vth cranial nerve.
2. orbital branch of pterygopalatine ganglion
3. branch of inferior ophthalmic vein which communicates with the
pterygoid plexus.

34.  serves as the posterior limit of surgical subperiosteal dissection
along the orbital floor.
OPTIC CANAL
Connects the orbit to the middle cranial fossa.
Contents : optic nerve and ophthalmic artery.
Average length : 6-11mm (lateral wall is shortest and medial wall is
longest)

35. Its orbital end is vertically oval (6*5mm),
 centre is circular (5*5mm),
 cranial end horizontal (4.5mm*6mm)
Clinical significance
Tumours such as optic nerve glioma and meningioma can
lead to unilateral enlargement of optic canal.
PERIORBITA
Orbital periosteum .
Loosely adherent to the bones.

36. Sensory innervation by branches of V’th cranial nerve.
Fixed firmly at
-Orbital margines (arcus marginale)
-Suture lines
-Lacrimal fossa (lacrimal fascia)
-Optic canal,Superior and inferior orbital fissures.
At the apex of orbit,the periorbita is thickened to form common
tendinous ring of Zinn.

37. FASCIA BULBI
•Also known as Tenon’s capsule or bulbar sheath.
•Dense,elastic and vascular connective tissue that surrounds the globe
( except over the cornea).
•Begins anteriorly at the perilimbal sclera,extends around the globe to
the optic nerve ,and fuses with dural sheath and the sclera.
•Separated from sclera by periscleral lymph space,which is in
continuation with subdural and subarachnoid spaces.
•The lower part of fascia bulbi is thickened and takes part in formation
of a sling on which the globe rests.(suspensory ligament of
Lockwood).

38. •Pierced anteriorly by six extraocular muscles
posteriorly by optic nerve,ciliary nerves and vessels.
•
SURGICAL SPACES IN ORBIT

40. SUBPERIOSTEAL
SPACE
Space between orbital bones and the periorbita.
Limited anteriorly by strong adhesions of
periorbita to orbital rim.

41. Tumours arising from the bones separate periobita from
bones,forming and effective barrier against the spread of tumour
towards eye.
PERIPHERAL ORBITAL
SPACE
Bounded
-peripherally by periorbita
-internally by the 4 recti with intermuscular
septa.
-anteriorly by the septum orbitale.

42. -posteriory it merges with the central space.
Tumours present in this space
CONTENTS
Peripheral orbital fat
Muscles
- Superior oblique
-Inferior oblique
-Levator palpebrae superioris
Nerves
-Lacrimal nerve
-frontal
-trochlear
-anterior ethmoidal
eccentric proptosis.

43. -posterior ethmoidal nerve
Veins
-superior and inferior ophthalmic veins
Lacrimal gland
Lacrimal sac
CENTRAL SPACE
Also called muscular cone or retrobulbar
space.
Bounded anteriorly by Tenon’s capsule and
sclera.
CONTENTS :
1.Optic nerve and its meninges

44. 2.Superior and inferior divisions of oculomotor nerve
3.Abducent nerve
4.Nasociliary nerve
5.Ciliary ganglion
6.Ophthalmic artery
7.Superior ophthalmic vein
8.Orbital fat
CLINICAL SIGNIFICANCE
Tumours in central space axial proptosis.
Tumours are often removed by lateral orbitotomy.

45. SUBTENON’S SPACE
oSpace around eyeball between sclera and Tenon’s capsule.
oPus collected in this area are drained by
incision of Tenon’s capsule through the
conjunctiva.
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