Orbit and Cranial Nerves of Eye Flashcards
What bone(s) make up the superior wall of the orbit?
frontal
lesser wing of sphenoid
What bone(s) make up the medial wall of the orbit?
mostly ethmoid
What bone(s) make up the lateral wall of the orbit?
zygomatic
greater wing of sphenoid
What bone(s) make up the inferior wall of the orbit?
mostly maxilla
zygomatic
What are the contents of the orbit?
eye, optic nerve, blood vessels, muscles, nerves, fat
Levator palpebrae attachments?
O: lesser wing of sphenoid
I: aponeurosis of eyelid
Orbicularis oculi attachments?
O: nasal portion of frontal bone
I: fascia of eyelids and skin around orbit
4 Rectus Muscle attachments?
O: all 4 arise from tendinous ring at back of orbit
I: sclera of eye
Superior oblique attachments?
O: medial roof of orbit
I: posterolateral eye
Inferior oblique attachments?
O: orbital surface of maxilla
I: posterolateral eye
Levator palpebrae superioris innervation and action?
N: occulomotor (CN III)
A: opens eyelid
Orbicularis occuli innervation and action?
N: facial (CN VII)
A: closes eyelid
BELLS PALSY
The tendon of the ________ passes through a pulley system.
superior oblique
CN III is responsible for all extraoccular movements with the exception of…
ABduction by Lateral Rectus (CN VI abducens)
depression and intorsion by superior oblique (CN IV trochlear)
Depression and extorsion of increases with ______ .
ADduction
Intorsion and elevation increases with _______.
ABduction
Where is occulomotor nucleus located?
rostral midbrain
CN ____ provides preganglionic parasympathetic fibers to ciliary ganglion
CN III
innervates sphincter of iris for pupillary light reflex
If an individual cannot ADduct or elevate, deficit is called
lateral strabismus
CN III
If an individual cannot ABduct, deficit is called
medial strabismus
CN VI
Lesion to CN IV may appear normal at rest, but deficit involves which movement?
cannot depress when Adducted
What is exotropia?
lateral strabismus: unopposed lateral rectus
eye rests in ER position
What are tests for CN III lesion?
eye movement
pupillary light reflex
vergence (pupils constrict as objects get closer)
What are the two components of pupillary light reflex?
CN II = sensory
CN III = motor
Diploplia, eyelid ptosis at rest, myadriasis (dilation of pupil) are signs of?
lesion of CN III
Trochlear nucleus is located where?
caudal midbrain
What nerve supplies the superior oblique muscle?
CN IV trochlear
CN IV lesion presents with
inability to move eye inferior when ADducted, diploplia, hypertropia (affected eye vertically deviated upward/extortion)
Abducens nucleus is located where?
caudal pons
What nerve supplies lateral rectus muscle?
CN VI abducens
What is esotropia?
medial strabismus - inability to ABduct the eye
sign of CN VI lesion
When the eye is ADducted, the superior oblique moves the eye _______.
inferiorly
When the eye is ADducted, the inferior oblique moves the eye _______.
superiorly
Name this lesion: With gaze straight ahead, right eye abducted because of weakness of medial rectus, right eyelid droops, and pupil is dilated.
R occulomotor lesion (CN III)
Name this lesion: With gaze L, right eye adducts but is elevated owing to weakness of superior oblique muscle.
R trochlear lesion (CN IX)
Name this lesion: With gaze R, right eye does not abduct because lateral rectus muscle is weak.
R abducens palsy (CN XI)
