Eye and Eye movements Flashcards
What are the bones of the orbit?
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Sphenoid
Lacrimal
Zygomatic
Maxillary
Ethmoid
Palatine
Frontal
What passes through the superior orbital fissure?
CNs 3, 4, V1, and 6
opthalamic Vs
What passes through the optic canal?
optin n
opthalamic A
What passes through the infraorbital fissure?
infraorbital A, zygomatic N (branch of maxillary N = V2)
What are the major paranasal sinuses to know?
Frontal = sup to orbit
ethmoid = medial to orbit
maxillary = inf to orbit
How do orbital blow out fractures usually occur and what can happen because of them?
usually occurs medial and inferiorly involving the maxillary bone (sometimes ethmoid)
blood and other orbital contents can prolapse –> go to maxillary sinus
can get iplopia, globe ptosis, exophthalmos
How is the eye positioned in relation to the orbit?
medial walls of orbit are parallel and in line w/ gaze
lateral walls are at right angles
axes of orbit diverge at 45 degree angles
(lateral side of eyeball is more exposed)
What are intorsion and extorsion and upon what axis do they occur?
intorsion = medial rotation
extorsion = lateral rotation
on AP axis
What extraocular Ms are innervated by what nerves?
SO4 LR6
occulomotor (CN III) –> levator palpebrae superioris, IO, SR, IR, MR
Trochlear N (CN IV) –> superior oblique
Abducent N (6) –> Lateral rectus
What is the action of superior oblique m?
(out and down)
abducts
depresses
medially rotates eye
What is the action of inferior oblique m?
laterally rotates
elevates
abducts
What occurs to elevation and depression when the eye is abducted by lateral rectus?
only rectus ms can produce elevation and depression
(so looking out and up tests SR, looking out and down tests IR)
What happens to elevation and depression during adduction by medial rectus?
only the oblique muscles can produce elevation and depression
(looking in and up tests IO, looking in and down tests SO)
What are the branches of V1 (opthalmic n) in the orbit?
first breaks into frontal n, nasociliary n, and lacrimal n
lacrimal n –> lacrimal gland
frontal –> supratrochlear and supraorbital n
nasociliary n –> posterior ethmoidal, anterior ethmoidal, infratrochlear, long ciliary, sensory root of ciliary ganglion
What nerves go through both the superior orbital fissure and the common tendinous n?
superior and inferior divisions of occulomotor n
nasociliary n (branch of V1)
abducent n (CN 6)
What structures go through the superior orbital fissure but not the common tendinous ring?
trochlear n (4)
superior ophthalmic v
frontal n (V1)
lacrimal n (v1)
How do sympathetics get to the eye and what do they innervate?
From T1-T4 –> synapse at superior cervical ganglion
postsynaptic fibers –> to internal carotid plexus –> either on CN 3 or V1 –> either to ciliary ganglion and then short ciliary ns
or on their own to muscles via long ciliary n(5) or CN3
What muscles are innervated by sympathetics in the eye?
Levator palpebrae superioris m
dilator pupilae
super and inf tarsal muscles
How do parasympathetics travel to and within the orbit?
Travel with CN III –> synapse in ciliary ganglion –> short ciliary n to ms
What eye muscles are innervated by PS?
sphincter pupilae
ciliary muscle
What types of fibers are in long ciliary nerves?
general sensory
post-synaptic sympathetics