The Orbit (Go OD's Go!) Flashcards
What is a blow-out fracture?
Fracture of the orbital floor, usually due to blunt or penetrating trauma
What are the seven bones of the orbit?
Ethmoid Lacrimal Palatine Frontal Sphenoid Zygomatic Maxilla
What bones form the superior wall of the orbit?
Orbital part of the frontal bone
Less wing of sphenoid
What bones form the medial wall of the orbit?
Orbital plate of ethmoid bone
Frontal process of maxilla
Lacrimal bone
Sphenoid bone
What bones form the lateral wall of the orbit?
Frontal process of zygomatic
Greater wing of sphenoid
What bones form the inferior wall of the orbit?
Maxilla
Zygomatic
Palatine
Which wall of the orbit is the thickest and strongest wall?
Lateral wall
Tell me about the orbital septum
A fibrous membrane that becomes continuous with the periosteum of the orbital margins. It is crucial to infection prevention into the orbit
The nasolacrimal duct conveys lacrimal fluid from the __________ to the ___________.
Lacrimal sac; inferior nasal meatus
Levator palpebrae superioris O: I: N: A:
O: lesser wing of sphenoid
I: super tarsus and skin of upper lid
N: CN III - superior division
A: elevation of upper eyelid
Superior Rectus O: I: N: A:
O: common tendinous ring
I: anterosup half of eye
N: CN III - superior division
A: elevation, intorsion, adduction
Inferior Rectus O: I: N: A:
O: common tendinous rings
I: anteroinf half of eye
N: CN III - inferior division
A: depression, Extorsion, adduction
Medial Rectus O: I: N: A:
O: common tendinous ring
I: anteromedial half of eye
N: CN III - inferior division
A: adduction
Lateral Rectus O: I: N: A:
O: common tendinous ring
I: anterolateral half of eye
N: CN VI
A: abduction
Superior oblique O: I: N: A:
O: body of sphenoid
I: sclera deep to superior Rectus
N: CN IV
A: intorsion, depression, abduction
Inferior oblique O: I: N: A:
O: anteromedial floor of orbit
I: sclera deep to lateral Rectus
N: CN III - inferior division
A: extorsion, elevation, abduction
The superior oblique, inferior oblique and lateral Rectus hold the eye where?
Abducted
How do the SO and IO keep the eye aligned on its axis?
Adducting the eye
How do you test the IO and SO using he H test?
Have patient direct eyes medially Look UP (IO) Look DOWN (SO)
How do the SR, MR and IR hold the eye?
Adducted
How do the SR and IR keep the eye aligned with its axis?
By abducting the eye
How can the H test be used to test the SR and IR?
Patient looks laterally Look UP (SR) Look DOWN (IR)
What does RADSIN stand for?
Recti adduct; superiors intort
What happens to the eye when there is a CN III nerve palsy? What might be the cause?
Eye is down and out
Pupil dilated
Complete ptosis
Suspect aneurism (usually in PCA)