about orbital cavity and eye

1. By : Sinchana S Kumbar
I yr
14O0027

2. The skull can be divided into two parts: the cranium and the
face.
The Cranium
2 Parietal bones
Occipital bone
2 temporal bones
Ethmoid bone
Sphenoid bone

3. The Face –
Frontal
2 Maxillary bones
2 Nasal bones
Vomer
2 Lacrimal bones
Palatine bones
2 Zygomatic bones
Mandible bone .

4. ORBIT:
 Bony cavity
 Made of - 7 bones *
 Contains ocular contents in it -
 Pear shaped , apex is directed post. , medially
and slightly upwards

5. DIMENSIONS
Rim : horizontally - ~ 40 mm
vertically - ~35 mm
Depth : Medially - ~42 mm
Laterally - ~ 50 mm
Inter orbital width - ~25 mm
Extra orbital width - ~100 mm
Volume – 30 ml

6. ORBITAL WALLS
It is comprised –
• Roof
• Floor
• Medial wall
• Lateral wall

7. ROOF

8. ROOF
• Frontal bone and lesser wing of sphenoid
• Located - ant cranial fossa and frontal sinus
• Impt landmarks in roof –
> Lacrimal gland fossa
> Fossa for TROCHLEA
> Supra orbital notch
> optic canal (lies b/w roof & body of sphenoid)

9. FLOOR

10. FLOOR
Maxillary ** , Palatine , Zygomatic bones
Roof of maxillary sinus
Impt. Landmarks seen are :
> infra orbital groove
> Inf. Orbital fissure ( separates the
lateral wall and floor)

11. THE THINNEST WALL / Lamina Papyracea

12. MEDIAL WALL*
• Ethmoid ,Lacrimal ,Maxillary & Sphenoid bones
• Location – adj. ethmoid and Sphenoids sinuses and Nasal cavity
• Ethmoidal sinus infection can lead to ORBITAL CELLULITIS
• Impt. Landmarks seen here are –
> Fronto ethmoid suture – Ethmoidal arteries
enters the orbit.

13. ORBITAL CELLULITIS
• It is a dangerous infection
• Usually caused by bacterial infection from the sinuses ( mainly
Ethmoid sinus)
• Which is behind the septum
• Clinical findings – Proptosis
- restriction of ocular motility
- pain on movement of globe

14. PRESEPTAL CELLULITIS
 It is an inflammatory condition that affects the tissue
of the eyelid.
 The disease can be limited by the location of the
orbital septum, which provides a barrier to prevent
spread into the orbit.
That could result in the development of orbital cellulitis.
 Clinical Findings - Swelling, redness, discharge, pain,
conjunctival injection, fever (mild), slightly blurred vision,
teary eyes, and some reduction in vision.

15. THICKEST WALL

16. LATERAL WALL***
• Zygomatic , greater wing of sphenoid bones
• Location – adj. middle Cranial & temporal fossa
• Impt. Landmarks seen –
> Tubercle of WHITNALL’S
> Superior Orbital fissure

17. ORBITAL MARGINS
1. Supra orbital notch – is medial to the center of the superior orbital margin
2. Supratrochlear notch – Nerves and Vessels pass through this groove
- present Superiorly in medial corner
4. Lateral area which is strongest is most exposed to injury
5. Infraorbital foramen – found in inf. Margin
- it is formed by maxillary bone and the zygomatic
bone

18. APERTURES IN ORBITAL CAVITY
 Ethmoidal foramen - > Place for ethmoidal arteries to pass through it
> In medial orbital wall
> It is the route for infections to spread from
sinuses
 Superior orbital fissure - > It separates Greater and Lesser wing of
sphenoid bone
> It is seen between roof and lateral wall
 Inferior orbital Fissure - > Seen in between Orbit and Lateral wall
> Allows the passage of blood vessels and
nerves

19.  Annulus of Zinn - > Fibrous ring , it is the origin for recti
muscles
> Nerves – Lacrimal ,frontal ,trochlear , sup
and inf. divisions of Oculomotor ,nasociliary , Abducens
nerves
> Sup Ophthalmic vein , Opthalmic artery
pass through this Common Tendinous Ring .

20.  Optic canal – > It is 8-10 mm long , 6.5 mm in
diameter
> located in Lesser wing of sphenoid
> Optic strut can be noticed

21. SINUSES
− Mucosa lined : Air filled cavities
− Decreases the weight of skull and helps in resonance
of voice
There are 4 sinuses
o Frontal Sinus
oEthmoid Sinus
oSphenoid Sinus
oMaxillary Sinus

22. Frontal Sinus : > Present above the orbit
> these 2 sinuses are separated by inter sinus septum
Ethmoid Sinus : > thin walled cavities
> infection can lead to ORBITAL CELLULITIS
Sphenoid Sinus - > present within the body of sphenoid
> Visual loss and Visual field abnormalities →
Sphenoid sinus
 Maxillary Sinus - > It is the largest sinus
> Infraorbital nerve and artery travel along the
roof of Maxillary Sinus

23. Soft tissues present in Orbit
PERIORBITA - It is basically covering
- At apex it fuses with Dura matter
- Ant : cont. with the orbital septum
- ARCUS MARGINALIS
ORBITAL FAT - Spaces which is not occupied by ocular content
,there is presence of Adipose tissue
- predominant at orbital APEX
ORBITAL SEPTUM – Palpebral fascia / Septum Orbitale
- At margins peri osteum continues with this
Connective tissue
- Strong barriers of Infection

24. VASCULATURE
– Ophthalmic Artery ← Internal Carotid Artery
The major branches of Ophthalmic artery are -
→ Branches to the EOM
→ Central Retinal Artery
→ Post. Ciliary Arteries
– External carotid Artery

25. INNERVATION
Sensory innervation – Ophthalmic and maxillary
divisions of CN V
Frontal and Lacrimal nerve – Medial canthus , upper lid ,
fore head
Nasociliary branch – ciliary branches
Short and Long ciliary nerves- Iris ,Cornea , Ciliary
muscle
Para sympathetic innervation – accommodation ,
pupillary constriction , lacrimal gland stimulation
Sympathetic innervation – pupillary dilation ,
vasoconstriction .

26. REFERENCE
 Kersten CR,Codere F,Dailey AR Jerry KP,et al.Orbit,Eye
lids and Lacrimal System .San Francisco: Dondrea
LC;2005-2006.
 Remington AL .Clinical Anatomy and Physiology of the
Visual System.3rd ed .Elsevier:Duncan L ;2012.
Thank you to Mrs .KARUNA - Mentor