cranial nerve examination Flashcards
what cranial nerve is affected in Bell’s palsy
7
why might the head be tilted in a cn 4 lesion
paralysis of superior oblique which brings eye inwards and down
this causes the patient to compensate by lifting the eye away from the side of the lesion
what is the main nerve that supplies taste
7
what nerve identifies irritant odors
5 (not 1)
what nerve is tested for when you ask the patient about walking downstairs
occulomotor/ trochlear
what does a skewed position of the eyes suggest
lesion of the medial longitudinal fasciculus ( carries information about the direction that the eyes should move)
what type of ptosis is found in horner’s
partial always
what type of ptosis is found in third nerve palsy
may be partial but is usually complete
what are some other causes of ptosis
congenital, myasthenia gravis
what is the innervation of levator palpebrae superioris
occulomotor and also sympathetic
what does miosis mean
small pupil
what is enopthalmos
partial backwards displacement of the eyeball
how do you use a snellen chart
ask patient to read the lowest line down possible
from 6m away
can wear corrective glasses
what should you do if they cant read the top line
can the count fingers/ recognise hand movements or see light
what are limbs of the light reflex (pupil constricts in response to light)
optic nerve afferent
psymp of occulomotor is efferent
what is the parasympathetic supply to the pupil controlled by
edinger westphal nucleus
what does the consensual response mean
the pupil on the opposite side to that which light is being shone in constricts
what are Argyll Robertson pupils
accommodate but do not react to light
caused by neurosyphilis
how far away from the patient should you place your finger when testing accommodation reflex
50 cm
what mediates the accommodation reflex
afferent- optic (
efferent- oculomotor (psymp from edinger westphal)
what parts of the brain ensure that both eyes move together
frontal and occipital lobes
cerebellum and vestibular nuclei
integrated in the brainstem
medial longitudinal fasciculus
where is the medial longitudinal fasciculus found
runs between nuclei of 3 and 4 in the midbrain and 6 in the pons
what supplies superior oblique
4
what supplies lateral rectus
6
what muscles elevates the eye
superior rectus and inferior oblique
what muscles depress the eye
inferior rectus and superior oblique
what is the function of superior oblique
depresses, abducts and intorts the pupil (crosses eyes)
what is the function of inferior oblique
elevates, abducts and extorts the pupil
where can lesions be found
supranuclear internuclear (mlf) nuclear nerve nmj muscle
what part of the brain controls eye pursuit
occipital lobe
patient tracks a moving target
how is nystagmus described
in the direction of the fast phase
what can cause peripheral nystagmus
vestibular system abnormalities
eight cn or nucleus
what causes retinal nystagmus
damage to the retina so inability to fix on an image
eye deviated laterally and slightly downward, pupil may be dilated and unresponsive, ptosis
cn 3 paresis
impaired depression of the fully adducted eye, head may be tilted to the opposite side to avoid diplopia
cn 4
impaired abduction
cn 6
what are the limbs of the corneal reflex
afferent- cn 5
efferent - cn 7
pt should blink
when you ask the patient to open their mouth against resistance, what muscle are you testing
pterygoids
if the lower jaw deviates to the left what does this suggest
left sided paralysis
lesion of the trigeminal nerve
what are the limbs of the jaw jerk reflex
both are 5
proprioception travels to the mesencephalic nucleus (midbrain)
then go to pontine motor nucleus
then to muscles of mastication
what does an abnormally brisk jaw jerk reflex suggest
bilateral upper motor neurone lesions affecting the corticobulbar pathway
what is bulb another name for
medulla
what muscles are being tested when pt is asked to grimace and show me your teeth
platysma and dilators
say me me me
lips and front of mouth tested
puff out your cheeks and don’t let me push them in
orbicularis oris
how do you differentiate between an upper and lower motor neurone lesion of the facial nerve
in an UMN lesion frontalis and orbicularis oculi are usually spared
in a lower motor neurone lesion the lower and upper part of the face are paralysed
bell’s palsy
swelling of the facial nerve withing the facial canal
may be hyperacusis
what is Bells phenomenon
eyeball turned upwards when the patient closes their eyes
what supplies taste in the anterior 2/3 of tongue
chorda tympanii from the facial nerve
what is webers hearing test
tuning fork is held on the forehead
what is rinnes test
tuning fork is held on the mastoid
tests for conductive deafness- bone conduction is better than air
what does it suggest if the uvula moves to the left side
there is a lesion of the vagus on the right side
parotid secretions and taste on posterior tongue
glossopharyngeal
what is the cranial accessory nerve
arises from the caudal extension of the nucleus ambiguous and joins the vagus
how is visual acuity calculated
distance at which test is performed in meters / line number that was read successfully
