Anatomy of orbit

Development of orbit

Develops from mesenchyme by ossification
6 th to 7 th

Developmental Anomalies :

Craniosynosotosis:
Brachycephaly
Oxycephaly
Scophocephaly
Trigonocephaly

Craniosfacial dysostois / Crouzon’ syndrome
Proptosis – shallow orbits
Hypertelorim - wide separation

Oxycephaly-syndactlye / Apert’ syndrome:
Flattened occiput , steep forehead ,
supra orbital

Bones of Orbit

Frontal Ethmoid Sphenoid
Lacrimal Palatine
Maxillary Zygomatic

Dimensions - orbit

30 ml –volume
35 mm vertically ,
40 mm horizontally
45

Boundaries of Orbit

Roof
Floor
Side walls
Orbital apex

Roof of orbit
Frontal bone [Orbital plate] & lesser wing of sphenoid
Separated

Orbital roof anomaly / fracture
CSF pulsation pulsatile
exophthalmos
Orbital meningocele

Medial wall
Body of sphenoid
Ethmoid
Lacrimal
Maxilla[frontal
process]

Orbital cellulitis
Extremely thin wall
Prone for damage & sinusitis spread
Infection across

Floor of orbit
Maxilla
Zygomatic
Palatine
Triangular segment
-- thinnest
Inferior orbital groove

Blow out fractures
Fragile barrier to maxillary
sinus
Due to trauma eyeball collapse

Le fort’s fracture

Type 2 - Pyramidal

Type 3 - Craniofacial dissociation

Lateral wall
Greater wing –sphenoid
Orbital surface –
Frontal process of zygomatic
Inferiorly – inf

Behind Zygomatic sphenoidal suture
lateral orbitotomy of greater wing
(

At frontal sphenoidal suture
-- meningeal foramen
Site of anastomosis

Orbital apex

Orbital apex syndrome
/ Tolosa - hunt syndrome :
Damage to structures

Other causes:
Inflammatory
Infectious
Neoplastic
Iatrogenic / traumatic
Vascular

Superior orbital fissure syndrome
/ Rochon – Duvigneaud syndrome

Contents of orbit

Eye ball
Orbital fat
Connective tissue system
Blood vessels
Nerves
Extraocular muscles

Eyeball - Applied anatomy:

Proptosis :
Dystopia
Enophthalmosis
Ophthalmoplegia

Connective tissue system

Periorbita
Orbital septum
Tenon’s capsule

Periorbita:
Loosely attached to orbital bone
Attached firmly to
Arcus marginalis
Trochlea
Lateral orbital

Orbital septum:
Interconnecting / circumferential radial webs of fascial system
support and

Anterior fascial system
Formed by condensation of fibrous septa
Lockwood

Tenon’s capsule
Dense elastic , vascular
Extent : from perilimbal sclera to

Surgical spaces in orbit :

Sub periosteal space
Peripheral space
Central space
Tenon’s

Extra ocular muscles

4 rectal muscles
2 oblique muscles
Two lid retractors
To serve in

Arterial supply

Venous drainage

Optic nerve

Intra orbital part = 25 mm out
of 4

Oculomotor nerve

Divides at anterior part of cavernous sinus before
Entering sup

Trochlear nerve

Runs medially from lateral wall
of cavernous sinus
Above Levator

Abducent nerve

Running inferior lateral to 3 rd
nerve then supplies ocular

Trigeminal nerve

Three terminal branches of ophthalmic division:
Frontal nerve supratrochlear
supraorbital
Lacrimal

Nasociliary nerve:
Communicating branch to sensory root of ciliary ganglion
Long ciliary nerves