The Orbit Anatomy and Surgical Spaces

1. DR. VIKAS KHATRI
DNB Resident
Sadguru Netra Chikitsalaya

2. Quadrangular truncated pyramids
Situated between the anterior cranial fossa above and the maxillary
sinus below.
ORBIT ANATOMY
Anterior Cranial Fossa
Maxillary Sinus
Orbit

4. 40mm
35mm
Orbital Index =
𝐇𝐞𝐢𝐠𝐡𝐭
𝐖𝐢𝐝𝐭𝐡
𝐗 𝟏𝟎𝟎
It Shows Racial Variation.
Megasenes - Greater than 89 ( Orientals )
Mesosenes - Between 83 and 89 ( Caucasians )
Microsenes - Less than 83 ( Blacks )
Volume of Orbit is about 29ml
Ratio between volume of Orbit and and
of the Eyeball is 4.5 : 1

6. Frontal Bone

7. Frontal Bone

8. Ethmoid Bone

9. Ethmoid Bone

10. Lacrimal Bone

11. Lacrimal Bone

12. Zygomatic Bone

13. Zygomatic Bone

14. Sphenoid Bone

15. Sphenoid Bone

16. Maxillary Bone

17. Maxillary Bone

18. Frontal Process of
Maxilla
Lacrimal
Bone
Orbital plate of ethmoid
bone
Body of
sphenoid

19. Lacrimal Fossa – Boundaries :
Anteriorly by – Anterior Lacrimal Crest of the Maxillary bone
Posteriorly by – Posterior Lacrimal Crest of lacrimal bone
Lacrimal Sac along with its fascia lies in the lacrimal fossa
Anterior Lacrimal Crest
of the Maxillary bone
Posterior Lacrimal Crest
of the lacrimal bone
Just behind the Posterior lacrimal Crest following
structures have their attachment :
• Horners Muscle
• Septum orbitale
• Check Ligament of Medial Rectus Muscle

20. RELATIONS MEDIAL TO THE MEDIAL WALL

21. Medial Orbital Wall is the thinnest wall-
1. Ethmoiditis is the most common cause of orbital cellulitis
2. Easily fractured during trauma and orbitotomy operation
During Surgery along Medial orbital wall Hemorrhage is
most troublesome due to injury to ethmoidal vessel.

22. Greater Wing of
Sphenoid Bone ;
Posteriorly
Zygomatic Bone ;
Anteriorly

23. Anteriorly, In Zygomatic Bone there is Bony Projection known as THE LATERAL
ORBITAL TUBERCLE OF WHITNALL
It Gives attachment to :
• Lateral check ligament
Suspensory ligament of eyeball
• Aponeurosis of levator palpebrae
superioris
• Lacrimal fascia
• Orbital septum
• Lateral canthal tendon

24. LATERAL WALL OF ORBIT
Laterally, Lateral Wall Separates Orbit from
Temporal Fossa Anteriorly and
Middle Cranial Fossa Posteriorly
Medially , Lateral Wall of Orbit is related to
• Lateral Rectus Muscle
• Lacrimal Nerves and Vessel
• Zygomatic Nerves and Vessel

25.  Lateral orbital wall protects only the posterior half of the orbit.
 Anterior half is not covered by bone. Hence, palpation of the
retrobulbar tumour is easier from the lateral side.

26. Orbital Plate of
Frontal Bone
Lesser Wing
of Sphenoid

27. Anterolateral Part of roof
Foosa for Lacrimal gland
At the Junction of Roof and Medial Wall
Trochlear Fossa for the Pulley of
Superior Oblique Muscle
Lacrimal Artery
and Vein

28. Orbital Plate of
Maxilla
Orbital Surface of
Zygomatic Bone
Palatine Bone

29. Inferior orbital groove
Inferior Oblique Muscle
Inferior orbital fissure
Inferior Rectus Muscle
Infraorbital Foramen

30.  Involved in blow out fracture of the orbit
 Invaded by tumors of the maxillary antrum
 Floor Of Orbit is best visualised with standard
Posteroanterior Radiographs

31. Blow out fracture of the orbit
Posteroanterior Radiographs of Orbit with Tear Drop Sign

32. Posterior End of Orbit
Apex has two Orifice
 Optic Canal
 Superior Orbital Fissure

33. Superior Orbital Fissure
Bounded by Lesser and Greater Wing of
Sphenoid
Lateral to Optic Canal
Divided into Upper, Middle and Lower parts
by Common Tendinous Ring

34. Frontal Nerve
Trochlear Nerve
Lacrimal Nerve
Structure passing Superior Orbital Fissure
Superior Ophthalmic Vein
Superior branch of oculomotor nerve
Abducent nerve
Nasociliary nerve
Inferior branch of oculomotor nerve
UPPER
PART
MIDDLE
PART

35. Optic Canal
Connects Orbit to Middle Cranial Fossa
Transmits :
Optic Nerve
Ophthalmic Artery
Average length – 6mm to 11mm
Orbital end – Vertically Oval (6x4.5mm)
Middle Part – Circular (5x5mm)
Cranial Part Horizontally Oval (4.5x6mm)
Optic Nerve Ophthalmic Artery

36. Syndromes –
a) TOLOSA HUNT SYNDROME-
Inflammation of the apex (idiopathic)
Ophthalmoplegia, Diplopia, Headaches, Dizziness, Nausea, Neck
stiffness, Photophobia, Blurred vision
b) SUPERIOR ORBITAL FISSURE SYNDROME-
Fracture of superior orbital fissure
Involvement of cranial nerves(Optic Nerve is spared)
Diplopia, Ophthalmoplegia, Ptosis, Proptosis

37. c) ORBITAL APEX SYNDROME
Infection, Inflammatory, Trauma, Tumor,
Involvement of cranial nerves – optic nerve (II), oculomotor nerve (III),
trochlear nerve (IV), abducens nerve (VI), and/or the ophthalmic branch of
the trigeminal nerve (V1)
Visual loss, Diplopia, Ophthalmoplegia, Ptosis, Proptosis, Chemosis

38. Anterior open end of the orbit
Formed by the orbital margins

39. Superior orbital margin
Formed by frontal bone
Contains :
Supraorbital Notch : Transmitting
the supraorbital nerve
Supratrochlear groove : 10mm
medial to supraorbital notch
transmitting Supratrochlear nerve
and artery
Supraorbital Notch Supratrochlear groove

40. Inferior orbital margin
Formed by
- Maxilla (medially)
- Zygomatic bone (laterally)
At the junction of medial 1/3rd and
lateral 2/3rd is a depression for the
origin of inferior oblique
Prone to fracture
Disruption of the inferior oblique
Diplopia
Infraorbital foramen
4-5 mm below infraorbital margin in line
with supraorbital foramen

41. Medial orbital margin
Formed of
- Anterior lacrimal crest on Frontal process of maxilla (Below)
- Frontal bone (Above)

42. Lateral orbital margin
# Formed by - Zygomatic bone
- Zygomatic process of frontal bone
# Frontozygomatic suture Narrowest and weakest part
Prone to separation by trauma
# It does not reach as far anterior as medial margin, therefore
anterior half of globe is not protected by bone.

43. Orbital periosteum
Gives out two processes-
a) Lacrimal fascia (encloses lacrimal
sac)
b) A process holding the trochlea
Extent of the periorbita-
Anteriorly -continues as periosteum at
the orbital margin giving off a stratum to
the orbital septum.
Posteriorly -unites with the dura mater
and the sheath of optic nerve

44. Loosely adherent to Bone but Firmly adherent to :
• Orbital Margin
• Orbital Fissure
• Optic canal
• Lacrimal fossa
• Sutures.
Significance -
Orbital roof surgery in the areas of fissures and sutures
may lead to CSF leakage

45. Elastic and vascular connective
surrounding entire globe except
the cornea.
Extends from perilimbal sclera to
the optic nerve fusing with its
dural sheath.
Tenons Capsule is separated
from sclera by Episcleral Space
(Tenons Space) and contains
fine trabeculae which connects
sclera with tenons capsule.
Tenons Capsule
Tenons Space
Sclera

46. Thickened inferiorly to form
suspensory ligament of Lockwood
Expansions of Tenon’s capsule-
a) Lateral check ligament
b) Medial check ligament
c) Sleeves around the extraocular
muscles

47. Structures piercing Tenons
Capsule-
a)Ciliary vessels and nerves
b)Venae vorticosae at equator
c)Extraocular Muscle
Tenons Capsule
Venae Vorticosae
Extraocular Muscle
Ciliary Nerves & Vessels

48. Subperiosteal Space
Peripheral Orbital Space
Sub-Tenons Space
Central Space

49. Space between Orbital
bone and Periorbita.
Subperiosteal Space

50. Peripheral Orbital Space
Bounded peripherally by
periorbita and internally by
extraocular muscle and
intermuscular septum
• Tumors in this space
produce eccentric
proptosis
• Peribulbar Block is given in
this Space

51. Central Space
Bounded anteriorly by Tenons
Capsule and peripherally by
Extraocular muscle and their
intermuscular septa
Tumours produces Axial
Proptosis
Also known as
Muscular Cone or
Retrobulbar Space
Contents of Central Space
• Optic Nerve
• Oculomotor Nerve
• Abducent Nerve
• Nasociliary Nerve
• Ciliary Ganglion
• Ophthalmic Artery
• Superior Ophthalmic Vein
• Central Orbital Fat

52. Sub-Tenons Space
Space between the Sclera
and Tenons Capsule
Sub-Tenon Injection is given
in this space
Pus collected in this space is
drained by incision of Tenons
Capsule through the
Conjuctiva

53. Supratrochlear Nerve
Supraorbital Nerve
Lacrimal Nerve
Frontal Nerve
Trochlear Nerve

54. Infratrochlear Nerve
Long ciliary nerves
Short ciliary nerves
Ciliary Ganglion
Abducent Nerve
Oculomotor Nerve

55. Supraorbital Artery
Lacrimal Artery
Posterior Ciliary Artery
Central Retinal Artery
Ophthalmic Artery
Supratrochlear Artery

56. Supratrochlear Vein
Supraorbital Vein
Superior Ophthalmic Vein
Vorticose veins
Cavernous Sinus
Inferior Ophthalmic Vein

57. Thank You