Cranial Nerves III, IV, VI Flashcards
nerves sometimes responsible for deviations of eye alignment
III, IV, VI
primary function of medial longitudinal fasciculus
coordinate eye movements
example of a lesion affecting the MLF
multiple sclerosis
the lobe that controls rapid or darting eye movement
frontal lobe
the lobe that controls smooth or following eye movement
occipital lobe
the result of uncoordinated attempts at controlling eye movements
nystagmus
disease of this nerve causes eyelid ptosis
CN III
disease of this nerve causes difficulty when looking down and in
CN IV
disease of this nerve causes inability to laterally deviate the eye on the same side
CN VI
disease of this nerve will diminish pupil constriction with bilateral symmetry
CN II
disease of this nerve will cause inability to constrict pupil in same eye
CN III
often due to lesions of the neck proximal to the carotid artery bifurcation
Horner’s syndrome
signs of Horner’s syndrome
ptosis, pupilloconstriction, facial anhydrosis, ipsilateral facial vasodilation
often due to lesions that are distal to the carotid artery bifurcation and that are along the internal carotid pathway
pupilloconstriction and ptosis
often due to lesions that are distal to the carotid artery bifurcation and that are along the external carotid pathway
vasodilation and anhydrosis
enophthalmos
inward sinking of the eyeball in the eye socket
3 components of accommodation
convergence, pupilloconstriction, lens thickening
the 3 components of accommodation are dependent on this CN
CN III
clinical findings that accompany nystagmus
nausea, vertigo, vomiting, ataxia
with nystagmus, which is the side with the problem?
the side that has the quick component
the 4 basic areas of the fundus of the eye that should be examined
optic disc, blood vessels, macula, general background
in the eye if the cup is not smaller than the disc it could indicate
glaucoma
with this disease the disc appears blurred with jagged edges
papilledema
this problem causes the optic disc to have a dead white color and also have a visual loss
primary optic atrophy
this problem causes the optic disc to be gray and ragged and could be secondary to another pathology
secondary optic atrophy
inflammation of the optic nerve
optic neuritis
inflammation of the optic disc
papillitis
optic neuritis or papillitis could indicate early signs of
MS
collections of degenerative deposits that often appear in the fundus of elderly people
Drusen bodies
when looking up and to the right, the nerve and muscle used in each eye:
right eye: superior rectus & CN III
left eye: inferior oblique & CN III
when looking laterally to the right, the nerve and muscle used in each eye:
right eye: lateral rectus & CN VI
left eye: medial rectus & CN III
when looking down and to the right, the nerve and muscle used in each eye:
right eye: inferior rectus & CN III
left eye: superior oblique & CN IV
when looking up and to the left, the nerve and muscle used in each eye:
left eye: superior rectus & CN III
right eye: inferior oblique & CN III
when looking laterally to the left, the nerve and muscle used in each eye:
left eye: lateral rectus & CN VI
right eye: medial rectus & CN III
when looking down and to the left, the nerve and muscle used in each eye:
left eye: inferior rectus & CN III
right eye: superior oblique & CN IV
how would a CN III dysfunction present on observation?
ptosis, eye points down and lateral
how would a CN IV dysfunction present on observation?
when patient reads may have double vision, have issues when looking down and in (would notice issues when doing fields of gaze test)
how would a CN VI dysfunction present on observation?
patient can’t look lateral, eyeball may be positioned more medially
which nerves are involved in the cavernous sinus?
3, 4, 5, 6
MS will affect medial longitudinal fasciculus in this way
inability to gaze lateral
a fast nystagmus would indicate problems in this area
frontal
a slow nystagmus would indicate problems in this area
occipital
heterotopia
deviation of bilateral eye alignment
exotropia
outward/lateral eye movement
esotropia
inward/medial eye movement
hypertropia
upward direction eye movement
hypotropia
downward direction eye movement
nerve that exits the midbrain just medial to the cerebral peduncle
CN III
compression to this nerve gives nerve palsy plus contralateral hemiparesis
CN III
nerve that supplies superior oblique muscles
CN IV
nerve that turns the eyeball down & in
CN IV
nerve that supplies lateral rectus
CN VI
nerve that functions in eye abduction
CN VI
CN III, IV, VI travel here
superior orbital fissure
