Pathways into the orbit & fractures of orbit Flashcards
what are the 3 main pathways by which structures can enter and leave the orbit?
optic canal
superior orbital fissure
inferior orbital fissure
what does the optic canal transmit?
the optic nerve and ophthalmic artery
what does the superior orbital fissure transmit?
lacrimal, frontal, trochlear (CN IV), oculomotor (CN III), nasociliary and abducens (CN VI) nerves
also carries the superior ophthalmic vein
what does the inferior orbital fissure transmit?
maxillary nerve (a branch of CN V), the inferior ophthalmic vein, and sympathetic nerves
what are the minor openings into the orbital cavity?
The nasolacrimal canal,
the supraorbital foramen,
infraorbital canal
function of the nasolacrimal canal?
drains tears from the eye to the nasal cavity
where is the nasolacrimal canal located?
located on the medial wall of the orbit
what does the infraorbital canal carry?
small neurovascular structures
what are the two major types of orbital fractures?
Orbital rim fracture
‘Blowout’ fracture
what is an orbital rim fracture?
This is a fracture of the bones forming the outer rim of the bony orbit
where does an orbital rim fracture usually occur?
at the sutures joining the three bones of the orbital rim – the maxilla, zygomatic and frontal
what is a ‘blowout’ fracture?
partial herniation of the orbital contents through one of its walls
how does a ‘blowout’ fracture usually occur?
This usually occurs via blunt force trauma to the eye
which walls of the orbit are weakest?
The medial and inferior walls are the weakest
where do contents herniate to in a ‘blowout’ fracture?
into the ethmoid and maxillary sinuses respectively
