This document provides an overview of the anatomy of the orbit. It discusses the embryology, dimensions, walls, apertures, fat pad, vasculature, innervation and radiological findings of the orbit. The roof, floor, medial, lateral and walls of the orbit are described in detail including important landmarks such as the lacrimal fossa and optic canal. The document also presents a case of an orbital injury and provides an introduction to the topic.

1. Anatomy of the orbit
Presenter: Dr. Mlaluko Rajabu (SHO 1)
MMed Ophthalmology
10/7/2023 1

2.  Case presentation
 Introduction
 Embryology
 Dimensions
 Orbital Rim and Wall
 Orbital Apertures
 Orbital fat pad
 Innervation, drainage, vasculature
 Radiological findings
Contents
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3. 24 years old male bodaboda guy presented at the emergency
department after getting an accident and sustaining injury on the
face a/w loss of consciousness for few minutes and bleeding per
nose but no bleeding per ears. On the examination, he was alert,
GCS 13/15. Ocular exam
RE: Bruises on the eyelids, hyperemic conjunctiva, normal cornea,
D/Q AC, pupil round and reactive.
LE: Ecchymosis, droopy eyelid, chemosis, clear cornea, D/Q AC,
pupil dilated and unresponsive to light
Case presentation
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4. VA OD: 6/9 OS: NPL
IOP OD: 12mmHg OS: 11mmHg
Extraocular movement
OD: Normal all extraocular movement
OS: Restricted extraocular movement
Pdx??
Ddx??
Case presentation
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5. Introduction
• The orbital cavities are a pair of large bony sockets that
contain the eyeballs, their associated muscles, nerves, vessels,
fat, and most of the lacrimal apparatus.
• The shape of the orbit is Truncated-pyramid.
• It has four walls, base and the apex.
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6. Embryology
• Orbital bones - derived from cranial neural crest cells
• First bone - Maxillary (at 6 wks of intrauterine life).
• Other bones develop at around 7 wks of intrauterine life.
• Lesser wing of sphenoid at 7 weeks
• Greater wing of sphenoid at 10 weeks
• They fuse at 16 weeks
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7. Cont…
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• Ethmoidal and sphenoidal bones are by endochondral
ossification. Greater wing of sphenoid bone and
others are by intramembranous type.
• NB: Ossification is complete at birth except at the
apex

8. Bony Orbit
• Composed of 7 bones:
1. Frontal Bone
2. Zygomatic Bone
3. Maxillary Bone
4. Ethmoid Bone
5. Sphenoid Bone
6. Lacrimal Bone
7. Palatine Bone
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9. Cont…
The orbital brim is made up by only maxilla, zygoma
and frontal bone. The frontal bone as major part.
 The medial walls are parallel and 25mm apart,
The lateral walls are at 90 degree to each other,
 Horizontal walls of individual orbit are at 45 degree.
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10. Cont…
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11. Dimensions
• Volume of orbital cavity ≈ 30 cc in adults.
• Rim:
- Horizontally ≈ 30-45mm
- Vertically ≈ 35 mm
• Depth
– Medial wall ≈ 30-45mm
– Laterally ≈10 mm less
• The cavity; widest; 1-1.5cm from the base
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12. Walls of the Orbital Cavity
• The orbit has four walls; 2 lateral walls, 1 roof
and 1 floor
• The walls are covered by periorbita except at
the foramina, fissures and canals.
• It continues with periostium of the scalp as
well as dura matter of the optic nerve sheath.
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13. Roof
• Triangular, concave, flat posteriorly.
• Underlies frontal sinus & Anterior cranial fossa
• Orbital plate of the frontal bone and the lesser wing of
the sphenoid posteriorly.
• Thin and fragile and in old age portions of the roof
may be absorbed.
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14. Important landmarks
I. The fossa for the lacrimal gland, lying anterolaterally
behind the zygomatic process of the frontal bone,
resides within the orbital roof.
II. Medially, the trochlear fossa is located on the frontal
bone approximately 4 mm from the orbital margin
and is the site of the pulley of the SOM, where the
trochlea, a curved plate of hyaline cartilage, is
attached.
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15. III. Supra-orbital foramen and supratrochlear notch: passes supra
orbital vessels and supra orbital branch of frontal nerves – site of
nerve block
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16. Orbital Roof Fractures
• Orbital roof fractures are usually caused by
penetrating trauma or missile injuries. In older
patients, frontal trauma is partially absorbed by the
frontal sinus, which diffuses the force and prevents
extension of the fracture along the orbital roof.
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17. Roof fractures
• Roof fractures are more common in young children
because the frontal sinus has not yet pneumatized and
also because the ratio of the cranial vault to the
midface is greater in children than in adults, making
frontal impact more likely with a fall.
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18. Cont…
• Complications of orbital roof fractures include
intracranial injuries, cerebrospinal fluid rhinorrhea,
pneumocephalus, subperiosteal hematoma, ptosis, and
extraocular muscle imbalance.
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19. Floor
• Shortest of orbital wall
• The floor of the orbit is composed of 3 bones:
1. Maxillary bone (major)
2. Palatine bone
3. Orbital plate of the zygomatic bone.
• Overlies maxillary sinus.
• Bordered laterally by IOF and medially by maxilloethmoidal
suture
• Only wall without sphenoid bone contribution
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20. 10/7/2023 20

21. Important Landmarks Floor
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 The infraorbital groove and infraorbital foramina,
which transmit the infraorbital nerve and vessels & the
maxillary division of the trigeminal nerve.

22. Clinical importance
• The orbital floor being quite thin is commonly
involved in blow-out fractures and is easily invaded
by tumours of the maxillary antrum.
• The floor of the orbit is best visualized with standard
of posterior anterior radiographs.
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23. Clinical finding
.
• The fracture will result to the injury of
infratrochlear/infraorbital nerve. Nose, cheek, upper
teeth
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24. Lateral Wall
• The thickest and strongest of the orbital walls
o Zygomatic bone and the greater wing of the sphenoid
bone.
• It is related to; middle cranial fossa and temporal
fossa
• Zygomatic groove and foramina -( nerve and vessels)
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25. Whitnall tubecle
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26. • This important landmark is the site of attachment for
the following structures:
• Suspensory ligament of the eyeball (Lockwood
suspensory ligament) of the globe
• Lateral canthal ligament
• Lateral horn of lateral rectus muscle
• Check ligament of levator superioris muscle
• Whitnall ligament
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27. 10/7/2023 27

28. Clinical importance
• The lateral wall of orbit protects only the posterior half of
the eyeball.
• The anterior half of the globe is not covered by bone on
the lateral side.
• Hence palpation of the retrobulbar tumours is easier from
the lateral
• Corneal foreign body removal is easier from lateral
side.
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29. Medial Wall
1. Frontal process of the maxillary bone
2. Lacrimal bone
3. Orbital plate of the ethmoid bone
4. Body of the sphenoid bone
• Located adjacent to the ethmoid and sphenoid sinuses and
nasal cavity
• The thinnest walls of the orbit are the lamina papyracea;
ethmoid sinuses with septa.
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30. Cont…
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31. Landmarks
 The lacrimal fossa: is formed by the
 Frontal process of the maxilla
 Lacrimal bone.
 Below, the lacrimal fossa is continuous with the bony
nasolacrimal canal, which extends into the inferior
meatus (the space beneath the inferior turbinate) of
the nose.
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32. Boundaries :
• Anterior- anterior Lacrimal crest
• Pos- posterior lacrimal crest
Dimensions:
• Length: 14mm
• Depth: 5mm
Content:
• Lacrimal sac
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33. Ethmoidal Foramina
• Between roof and medial wall
• Are in the frontoethmoidal suture or in frontal bone;
• Anterior ethmoidal foramen; opens in anterior cranial
fossa, at side of cribriform plate; Transmits: anterior
ethmoidal nerve and artery
• Posterior ethmoidal foramen; transmits posterior
ethmoidal nerve and artery
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34. Weber’s suture
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• In the frontal process of maxilla just anterior to the
lacrimal fossa a fine groove known as the sutura
longitudinalis imperfecta of Weber
• This suture runs parallel to the anterior lacrimal crest.
Small branches of infraorbital artery pass through this
groove to supply the nasal mucosa.
• This should be anticipated in any lacrimal sac surgery
to avoid unnecessary troublesome bleeding.

35. Sutura longitudinalis imperfecta..
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• .

36. Superior Orbital (Sphenoidal) Fissure)
• Lies between the roof and the lateral wall of orbit;
separating the lesser and greater wings of sphenoid
• “Comma-shaped”; 22mm long; wider medial, narrow
laterally
• Largest communication between orbit and middle cranial
fossa
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37. 10/7/2023 37

38. Cont…
• The SOF is divided into 3 compartments by annulus
ring of Zinn.
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39. Cont..
• Superior compartment: frontal and lacrimal
branches of CNV1, trochlear nerve, superior
ophthalmic vein
• Middle compartment: Superior and inferior
branches of the CNIII, abducens nerve, nasociliary
branch of CNV1, inferior ophthalmic vein
• Inferior compartment: Inferior ophthalmic vein
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40. Superior orbital fissure syndrome
• Also known as Rochon Duvigneaud syndrome.
• It is due to lesions on the components of the SOF just
anterior to the orbital apex.
• It involve other nerves and sparing optic nerve.
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41. Clinical presentations
• External ophthalmoplegia; impaired EOM
movements
• Internal ophthalmoplegia is fixed dilated
pupils.
• Double vision (horizontal, vertical or oblique)
• Ptosis of upper eyelid.
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42. Cont…
• As affected eye does not move whereas contralateral
normal eyeball moves focal axis gets
disturbedDiplopia.
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43. Inferior Orbital (Sphenomaxillary) Fissure
• Lies between the lateral wall and floor of the orbit,
joins orbits to the pterygopalatine and infratemporal
fossae; lies between the greater wing of sphenoid and
the maxilla
• Runs inferolaterally to the optic foramen, at the medial
end of the superior orbital fissure, and runs
anterolaterally for 22 mm to end about 2 cm from the
inferior orbital margin.
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44. Cont…
Transmits of structures:
• Infra orbital nerve and Zygomatic nerve (from the
Maxillary division of Trigeminal nerve)
• Inferior ophthalmic vein leading to the
• Infra orbital artery (from the maxillary artery & vein)
• Symphathetic nerves
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45. Optic Foramen (a.k.a Optic Canal)
• The optic canal is 8-10 mm long and is located within
the lesser wing of the sphenoid.
• Connects the middle cranial fossa to the apex of the
orbit.
• This canal is separated from the superior orbital
fissure by the bony optic strut.
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46. Cont…
• Close to: sphenoidal air sinus and sometimes to a
posterior ethmoidal sinus;
• The longer the optic canal, the narrower it is.
• Transmits: optic nerve and ophthalmic artery.
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47. Orbital fat
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 Located posterior to the orbital septum and
anterior to the levator palpebral aponeurosis of
UL and capsulopalpebral fascia of lower eye lid
 It acts as cushion to the globe
 Infra trochlear nerve and medial palpebral artery
branches of ophthalmic artery courses thru the
medial fat

48. Orbital fat
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49. Orbital vasculature
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• Mainly by ICA with some contribution from internal
maxillary and facial branches of ECA.
• ICA gives its first big branch ophthalmic artery as it
exits the cavernous sinus

50. Orbital vasculature
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• Mainly by ICA with some contribution from internal
maxillary and facial branches of ECA.
• ICA gives its first big branch ophthalmic artery as it
exits the cavernous sinus

51. Venous drainage
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• Superior ophthalmic veincavernous sinus
• Inferior ophthalmic veinpterygoid plexus
• Vortex vein drain from choroid to either of the above
• Central retina vein

52. Lymphatic drainage
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• Pre-auricular lymphnodes
• Submandibular lymphnodes
• Retropharyngeal lymphnodes

53. Innervation
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 Optic nerve
 Infra-orbital nerve
 Zygomatic nerve
 Lacrimal nerve
 Frontal nerve
 Supra-orbital nerve
 Supra-trochlear nerve
 Infraorbital nerve
 Symphathetic and parasymphathetic nerves
 CN III, IV and VI

54. Radiological studies
• CT
• MRI
• Ultrasonography (B-Scan)
• X ray
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58. SPA
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59. G.O
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60. RB
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61. IVFB
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62. Cont..
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63. Cont…
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64. References
• Clinical Anatomy of the Eye, 2nd Edition, by Snell.
Richard S et al
• Wolff’s Anatomy of the Eye and orbit, 8th edition, by
Anthony J. Brown et al
• Fundamentals and Principles of ophthalmology,
2022-2023 edition, AAO
• EyeWiki
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