DocGuy Short Notes: Anatomy of the Orbit, Eye & Lacrimal Apparatus

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ANATOMY
Medicine Made Simple

, Orbit & Eye
Orbit
Orbital Skeleton
 Orbital margin
 Above – frontal bone 
 Lateral – frontal & zygomatic 
 Inferior – zygomatic & maxilla 
 Medial – maxilla & frontal 

 Walls
 Roof – orbital plate of frontal bone & lesser wing of sphenoid
 Lateral – zygomatic & greater wing of sphenoid
 Floor – orbital plate of maxilla, zygomatic, palatine bone 
 Medial – anterior lacrimal crest on frontal process of maxilla, posterior lacrimal crest on lacrimal, orbital plate
of ethmoid, body of sphenoid 




 Clinicals
1. In blow out fracture, orbital floor or medial wall may be damaged.
2. Fracture of floor causes herniation of orbital fat into maxillary sinus
3. Entrapment of an extra-ocular muscle causing diplopia
4. Injury to infra-orbital nerve

 Openings
Supra orbital notch - supraorbital nerve & vessels 
Infraorbital groove - infraorbital nerve & vessels. Lodges the orbitalis muscle 
Nasolacrimal canal - nasolacrimal duct 
Inferior orbital fissure - maxillary & zygomatic nerves, branch of inferior ophthalmic vein, sympathetics
(gap between lateral wall and floor) 
Superior orbital fissure - L, F, T, S, O, N, I, A
(gap between lateral wall and roof)
 Optic canal - optic nerve & ophthalmic artery
 Anterior & posterior ethmoidal foramina – at the junction of roof and medial wall. Transmits the anterior &
posterior ethmoidal nerves & vessels 
 