cranial nerve fx Flashcards
anosmia
loss of the sense of smell (this can be unilateral or bilateral).
homonomous
overlapping visual fields
hemianopsia
one side
quadrantanopsia
loss of visual perception of one-quarter of the visual world.
scotoma
patch of vision loss.
strabismus
is a position of the eyes where they are not directed at the same target (in some parts of the country this is termed a “squint”).
diplopia
double vision
myopia
inability to see at distance (“nearsighted”) with light focusing in front of the retina… convergene of image occurs before retina
hyperopia
far sighted, behind retina convergence
amblyopia
literally means “dim eye”. This is a drifting or “lazy” eye that usually happens because one eye has bad vision. The brain often “turns off” control of that eye and the eye drifts. The patient usually does not have diplopia because input from that eye is turned off.
visual acuity problems and pinhole testing
improve-refractive
do not improve- retinal/optic nerve
mononuclear problems
anterior to optic chiasm
homonymous visual field problems
posterior to optic chiasm
bitemporal hemianposia
problems AT optic chiasm
most of visual cortex supplied by
posterior cerebral arteries
when a person has double vision, images will be furthest apart when
eyes look in the directon that the weak muscle is most active
horizontal diplopia results from
weakness of lateral or medial rectus muscles
verticle diplopia
weakness of one or the other muscles
the bad eye
sees the image furthest towards the perphery of vision
lateral gaze center
frontal eyefields
paramedian pontine reticular formaton
vertical gaze center
rostral midbrain
pretectal areas
ptosis could be due to..
1) weakness of levator palpebrae muscle
2) CNIII damage
Horner’s syndrome
ptosis meiosis anhidrosis flushing damage to symps
center for pupillary light reflex
pretectal area
sympathetics
dilate pupil
parasymps (CN III)
constrict to lght
only division of trigem with motor fibers
mandibular
trigem ganglion location in head
lateral to sella turcica/pituitary in cavernous sinus
CNV enters
pons
lateral brainstem lesions cna block
ipslateral pain from face
Bell’s Palsy
damages the facial nerve in the facial canal – weakens all muscles of facial expression on the side of lesion
- Damage to corticobulbar fibers (from cortex to the pons)
produce supranuclear weakness of the lower face (sparing of forehead) on the contralateral side
hyperacusis is what muscle
stapedius
loss of taste in anterior 2/3 of tongue and hyperacusis
CN VII
can not be damaged by lesions of the brain
Hearing
[because it is bilateral ]
sensorineural deafness
Inner ear and CN VIII lesions
caloric testing
is the only way to check each inner ear vestibular function independently
the patient is awake, the eyes will drift slowly toward the side of cold water with rapid correction to opposite side (the opposite for warm water)
caloric testing and damaged vestibular apparatus
this is because there is a tonic balance in vestibular input from both ears
cold water decreases, warm water increases tonic input
damaged ear acts like cold water caloric
glossopharyngeal nerve provides sensation to
carotid baroreceptor
chemoreceptor
pharynx and middle ear
vagus nerve activates
elevator of the soft palate – will elevate with deviation of base of uvula AWAY from the side of lesion
lesion of recurrent laryngeal (vagus)
painless hoarseness wth weakness or paralyss of vocal cord on that side
spinal accessory nerve pathway
cervical spinal cord–> enters through foramen magnum–>exits jugular foramen
corticobulbar damage (like a stroke) + mouth
slightly weaken contralateral side of tongue and soft palate
jaw jerk reflex
afferent- trigem
efferent- trigem
corneal reflex
afferent trigem
efferent-facial
gag reflex
afferent- glossopharyngeal
efferent- vagus
cough reflex
afferent vagus
efferent- resp centers and vagus
BRR
afferent - glossopharyngeal
efferent- vagus
weber’s test
lateralzed toward side of conductive deafness and away from sensorineural
