1. REVIEW OF CLINICAL ANATOMY & PHYSIOLOGY OF THE ORBIT
Dr. Ayesha Abdullah

2. By the end of this lecture the students would be able to;
LEARNING OUTCOME
By the end of this lecture the students would be able to;
“correlate the structural organization of the orbit with its functions and clinical significance”

3. ANATOMY OF THE ORBIT
The orbital cavities are …………

4. Adult orbital dimensions
Entrance height
35 mm
Entrance width
40 mm
Medial wall length / depth
45 mm
Volume
30 cc
Distance from the back of the globe to the optic foramen
18 mm
45mm
35mm
45mm

6. SALIENT ANATOMICAL FEATURES
7 bones
6 contents
5 important relationships
4 walls
4 margins
4 important openings

7. v

8. Bones & walls
MZSF
ELP

9. Which orbit ?

10. IMPORTANT OPENINGS OF THE ORBIT
Optic Foramen
Where?
size?
what passes through?
Clinical significance?
Superior orbital fissure
What passes through?
What is annulus of Zinn?
Inferior orbital fissure:
Optic Foramen: This is an important opening at the back of maximum diameter of 6.5mm ( adults). It is present at the apex of the orbit. It opens into the optic canal, which contains the optic nerve, ophthalmic artery & sympathetic nerves. So the optic nerve enters the orbit through the optic foramen. Optic foramen enlargement can occur with tumour of the optic nerve like optic nerve glioma. Trauma can cause fracture of the optic canal & damage the optic nerve.
What passes through Superior orbital fissure
The 3rd cranial nerve - Oculomotor
The 4th cranial nerve – Trochlear
Branches of 5th cranial nerve (Lacrimal nerve, Frontal nerve,Nasociliary nerve)
6th cranial nerve – Abducent.
Superior ophthalmic vein en route to cavernous sinus
Edges of this fissure give attachment to an important ligament that gives rise to the muscles of the eyeball called the annulus of zinn.
Inferior orbital fissure:
This is an other cleft, which separates the lateral wall and the floor it communicates with the pterygopalatine fossa & the pterygoid venous plexus. Important structures passing through it are:
Braches of the 5th nerve
Some veins and arteries

11. Openings of the orbit Inferior orbital foramen What passes through
Nasolacrimal canal
Where?
What passes through?
Clinical significance
Inferior orbital foramen
What passes through
Clinical significance?
Nasolacrimal canal
It extends from the lacrimal fossa to the inferior turbinate in the nasal cavity
Other openings are the ehtmoidal foramina & foramina of the zygomaticotemporal & zygomaticofacial canals

13. Sensory Nerve Supply of the Face

14. Orbital walls Frontal bone and sphenoid lesser wing
Roof
Frontal bone and sphenoid lesser wing
Lacrimal gland, trochlea
Superior orbital notch
Brain
Floor
Zygomatic, maxilla and palatine bones.
weak part
Infraorbital groove & canal for the infraorbital nerve
Maxillary sinus.

15. Medial Wall
lacrimal, maxillary, ethmoid & sphenoid
Thinnest wall
Lamina papyrecea
It separates the orbit from the nasal cavity, the ethmoidal and the sphenoidal sinuses
Lateral Wall
Zygomatic & Sphenoid (greater wing)
Stronger wall
It separates the orbit from the (temporal fossa) and the brain

16. Roof

17. Medial wall
Floor

18. IMPORTANT RELATIONS OF THE ORBIT
Brain
Para nasal sinuses
Nasal cavity
Cavernous sinus
Pterygopalatine fossa
Brain : Orbit is closely related to the brain in relation to its roof and lateral wall.
Para nasal sinuses: Orbit is intimately connected to the paranasal sinuses.
Maxillaly sinus via the floor.
Ethmoidal and sphenoidal sinus via the medial wall.
Frontal sinus at the roof.
Any infection can easily spread to the orbit from the sinuses.
Nasal cavity: Nasal cavity is related to the orbit at its medial or inner wall & through the nasolacrimal duct
Cavernous sinus via the veins of the orbit
Pterygopalatine fossa via the inferior orbital fissure

19. Orbit as seen from above

20. Relations of the orbit to the paranasal sinuses :FS, frontal sinus; ES, ethmoidal sinus; MS , maxillary sinus; SS, sphenoid sinus- American Academy of Ophthalmology

21. CONTENTS OF THE ORBIT Eyeball & the optic nerve
Muscles – To move the eyeball.
Nerves –
To move the muscles ( III, IV, VI).
To carry different sensations ( V)
parasympathetic innervation ( accommodation, pupillary constriction & lacrimal gland stimulation
Sympathetic innervation ( pupillary dilatation, vasoconstriction, smooth muscles of the eye lids & hidrosis)

22. CONTENTS OF THE ORBIT
Blood vessels ( branches of ophthalmic artery, superior & inferior ophthalmic veins)
Fat & orbital fascia – For padding purposes & for smooth movements
Most of the Lacrimal Apparatus (lacrimal gland & part of the tear drainage system)

24. Lacrimal gland and the
view of the orbit from
the roof

26. Orbital fascia Periorbita Orbital septum Tenon’s capsule
Fascial spaces intraconal extraconal subtenon
subperiosteal

27. Subperiosteal space
Extraconal space
Intraconal space

28. Structure of the lids-AAO

29. VIEWS : AXIAL VIEWS
RADIOGRAPHIC ANATOMY OF THE ORBIT

30. CORONAL VIEW

31. SAGITTAL VIEW

34. AXIAL CT SCAN

38. Summary
Orbit is the protective casing for the delicate visual apparatus - the eyeball
It is made up of 7 bones, has 4 margins, 4 walls/ boundaries, 4 important openings , 5 important relations & 6 contents
Infection can spread to the brain from the orbit directly or through the haematogenous spread- Orbital septum is a barrier to infection
Trauma mostly damages the medial wall & the floor (the weakest parts give way)
The symptomotology of orbital diseases is reflective of its clinical anatomy