the orbit
TRANSCRIPT
THE ORBIT
By : Sinchana S Kumbar I yr 14O0027
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
The Face – Frontal 2 Maxillary bones 2 Nasal bones Vomer 2 Lacrimal bones Palatine bones 2 Zygomatic bones Mandible bone .
ORBIT:
Bony cavity Made of - 7 bones * Contains ocular contents in it -
Pear shaped , apex is directed post. , medially and slightly upwards
DIMENSIONS
Rim : horizontally - ~ 40 mm
vertically - ~35 mmDepth : Medially - ~42 mm
Laterally - ~ 50 mmInter orbital width - ~25 mm
Extra orbital width - ~100 mm
Volume – 30 ml
ORBITAL WALLS
It is comprised – •Roof•Floor•Medial wall•Lateral wall
ROOF
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)
FLOOR
FLOORMaxillary ** , Palatine ,
Zygomatic bones Roof of maxillary sinus Impt. Landmarks seen are :
> infra orbital groove
> Inf. Orbital fissure ( separates the
lateral wall and floor)
THE THINNEST WALL / Lamina Papyracea
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.
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
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.
THICKEST WALL
LATERAL WALL***
• Zygomatic , greater wing of sphenoid bones
• Location – adj. middle Cranial & temporal fossa
• Impt. Landmarks seen –
> Tubercle of WHITNALL’S
> Superior Orbital fissure
ORBITAL MARGINS1.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
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
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 .
Optic canal – > It is 8-10 mm long , 6.5 mm in diameter > located in Lesser wing of sphenoid > Optic strut can be noticed
SINUSES
− Mucosa lined : Air filled cavities − Decreases the weight of skull and
helps in resonance of voice
There are 4 sinuses o Frontal SinusoEthmoid Sinus oSphenoid Sinus oMaxillary Sinus
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
Soft tissues present in Orbit PERIORBITA - It is basically covering - At apex it fuses with Dura matter - Ant : cont. with the orbital septum - ARCUS MARGINALISORBITAL FAT - Spaces which is not occupied by ocular content ,there is presence of Adipose tissue - predominant at orbital APEXORBITAL SEPTUM – Palpebral fascia / Septum Orbitale - At margins peri osteum continues with this Connective tissue - Strong barriers of Infection
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
INNERVATION
Sensory innervation – Ophthalmic and maxillary divisions of CN V
Frontal and Lacrimal nerve – Medial canthus , upper lid , fore head
Nasociliary branch – ciliary branchesShort and Long ciliary nerves-
Iris ,Cornea , Ciliary muscle Para sympathetic innervation –
accommodation , pupillary constriction , lacrimal gland stimulation
Sympathetic innervation – pupillary dilation , vasoconstriction .
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
Thank You