Quiz 3 Flashcards
what are the 4 key functions of the CNs?
1) motor innervation to muscles of the face, eyes, tongue, jaw, and neck
2) sensory info from skin and muscles of the face and TMJ
3) transmit special sensory info (hearing, vision, smell, vestibular fxns)
4) parasympathetic regulation of pupil size, curvature of lens of eye, HR, BP, breathing, and digestion (3, 7, 9, 10)
what reflexes are mediated by CN 2 (afferent sensory) and 3 (efferent motor)?
pupillary reflex, accomodation reflex, and direct/consensual responses
what is the pupillary reflex?
shine pen light on eyes and the pupils constrict
what is the accomodation reflex?
thickness of the lens changes based on distance of object being focused on
what are direct vs consensual responses?
direct=in the eye being tested
consensual=in the other eye
what are the reflexes mediated by CN 5 (afferent sensory) and CN 7 (efferent motor)?
jaw jerk and corneal
what reflexes are mediated by CN 9 and CN 10?
gag reflex and swallowing reflex
what are the olfactory bulb targets?
pyriform cortex, olfactory tubercle, amygdala, and entorhinal cortex
where does the pyriform cortex go?
orbitofrontal cortex
where do the olfactory tubercle and amygdala go?
orbitofrontal cortex
thalamus
hypothalamus
where does the entorhinal cortex go?
hippocampal formation
where are the olfactory receptors?
in the nose
what is the primary olfactory cortex?
pyriform cortex
the orbitofrontal cortex and thalamus relay what info to each other?
conscious perception of smell
what makes up the secondary cortex?
insula, cingulate cortex, and orbitofrontal cortex
what is responsible for the emotional aspect of smell?
the hypothalamus
what is responsible for the memory of smell and the action afterward?
the hippocampal formation
what does the insula do?
combines taste and smell info
survival functions
perception of flavor
parasympathetic and sympathetic fxns
what would a lesion in the insula result in?
loss of taste and smell
what is the hippocampus responsible for?
hunger
what is the insula/orbitofrontal cortex responsible for?
smell and taste related to addiction (coffee)
what is the amygdala responsible for?
smell influencing hunger
memories related to smell (esp strong emotions)
emotions to food
what are the medial and lateral para-hippocampus responsible for?
quality of smell
sends signal to secondary olfactory area
action related to smell
what is the medial para-hippocampus responsible for?
judgements made based on smell
smell fire, run away
what is the lateral para-hippocampus responsible for?
integrating smell with declarative memory
related to the ability to verbalize what a smell is
what does CN 1 dysfunction result in?
anosmia/hyponosmia
parasmia
olfactory hallucinations
what is anosmia/hyponosmia?
absent/decreased ability to smell
can be temporary, permanent, or progressive
can be congenital or from infection (meningitis/cold)
what would cause permanent anosmia/hyponosmia?
a tumor in the olfactory groove
what is parosmia?
distorted sense of smell, usually unpleasant (something pleasant smells unpleasant)
usually post trauma
what are olfactory hallucinations?
unpleasant smell in the absence of stimuli
what are olfactory hallucinations usually associated with?
insular seizures and epileptic disorders
what can cause olfactory nerve lesions?
TBI-permanent
meningitis-temporary
PD-permanent progressive
Alzheimer’s disease-permanent progressive
Kallmann syndrome
t/f: TBIs often shear nerves in the cribriform plate
true
what is Kallmann syndrome?
genetic condition related to delayed/absent puberty and includes an impaired sense of smell
what is the fxn of CN 2 (optic nerve)?
visual acuity
visual fields
red saturation
what is the somatic motor fxn of CN 3?
levator palpabrae superioris
all extraocular muscles except sup oblique and lat rectus
what is the parasympathetic fxn of CN 3?
pupillary constrictor and ciliary muscles (attached to the lens) for near vision
what is the somatic motor fxn of CN 4?
superior oblique
what is the somatic motor fxn of CN 6 (abducens)?
lateral rectus
what CN makes up the afferent arm of the accomodation reflex?
CN 2
what CN makes up the efferent (motor) arm of the accomodation reflex?
CN 3
what is the fxn of CN 5 (trigeminal)?
innervate muscles of mastication
what are the 3 division of the trigeminal nerve (CN 5)?
V1
V2
V3
what is the V1 division of the trigeminal nerve (CN 5)?
ophthalmic
sensory
forehead
what is the V2 division of the trigeminal nerve (CN 5)?
maxillary
sensory
bw nose and mouth
what is the V3 division of the trigeminal nerve (CN 5)?
mandibular
sensory and motor
mandibles and temporalis
what is the somatosensory fxn of the trigeminal nerve (CN 5)?
afferents for touch , nociceptive, and temp info from the face, ant 2/3 of tongue, anterosuperior external ear, internal ear canal, sinuses, teetch, and meninges
proprioception from the face, TMJ, and tongue
what is the motor fxn of the trigeminal nerve (CN 5)?
efferents to muscles of mastication and tensor tympani muscle
what is the reflex fxn of the trigeminal nerve (CN 5)?
afferent limb corneal reflex
what is trigeminal neuralgia (AKA tic doulourex)?
abrupt onset of severe, sharp, stabbing, electric shock pain in the distribution of one/more branches of the trigeminal nerve lasting less than 2 minutes and can occur several times a day
what branches of the trigeminal nerve (CN 5) are usually involved in trigeminal neuralgia?
V2 or V3, not usually V1
what triggered the symptoms of trigeminal neuralgia?
chewing, talking, brushing teeth, shaving
what are the causes of trigeminal neuralgia?
idiopathic
classic (demyelination)
secondary to trauma, MS, post herpetic neuralgia, or tumor
are more males or females over 50 y/o affected by trigeminal neuralgia?
females
what is the Hallmark disease of the trigeminal nerve?
trigeminal neuralgia
t/f: in severe cases of trigeminal neuralgia, you can have dull aching pain in the absence of an attack
true
if there is a CN 5 lesion, is the direct or consensual response of the corneal (blink) reflex affected?
no direct or consensual responses
if there is a lesion in the spinal trigeminal nucleus, is the direct or consensual response of the corneal (blink) reflex affected?
no direct or consensual responses
if there is a lesion in CN 7, is the direct or consensual response of the corneal (blink) reflex affected?
direct response is lost, but consensual response is in tact if stimulated on the same side as the lesion
direct response is in tact, but consensual response is lost if stimulated on the opposite side of the lesion
what is the stimulus in the corneal (blink) reflex?
cornea is touches and you blink
what CN makes up the afferent (sensory) arm of the corneal (blink) reflex?
CN 5 (trigeminal)
what CN makes up the efferent (motor) arm of the corneal (blink) reflex)?
CN 7 (facial)
what does CN 5 do in the corneal (blink) reflex?
synapses on the interneuron in the spinotrigeminal nucleus in the lateral medulla
trigeminal nerve –> spinal trigeminal nucleus
what does CN 7 do in the corneal (blink) reflex?
facial nerve nucleus–>facial nerve
reflexive closing of the eyelids
ipsilateral response-direct
contralateral response-consensual
what is the direct response?
the response in the ipsilateral eye
what is the consensual response?
the response in the contralateral eye
is there ipsilateral face drooping with a CN 5 or CN 7 lesion?
CN 5 lesion
if there is a CN 7 lesion on the L and the L side is stimulated, what occurs?
no direct response
in tact consensual response
if there is a CN 7 lesion on the L and the R side is stimulated, what occurs?
in tact direct response
no consensual response
if there is a CN 7 lesion on the R and the R side is stimulated, what occurs?
no direct response
in tact consensual response
if there is a CN 7 lesion on the R and the L side is stimulated, what occurs?
in tact direct response
no consensual response
would CN 5 and CN 7 lesions be UMN or LMN lesions?
LMN lesions
would a spinal trigeminal nucleus lesion be an UMN or LMN lesion?
UMN lesion
if there is an UMN lesion, what happens with the corneal (blink) reflex?
no direct or consensual responses
what is one of the most common BS strokes?
lateral medullary lesion
if there is red nucleus, RAS, or cerebellar damage, what happens to the speed and strength of the corneal (blink) reflex?
it is slowed
what is the jaw jerk reflex?
the mandible is tapped just below the lips at the chin while the mouth is held open slightly
is the jaw jerk reflex test performed often? why or why not?
no, bc a (+) response isn’t usually present and can’t tell us what side is affected
if there is a LMN lesion, what happens with the jaw jerk reflex?
areflexia/hyporeflexia
the jaw will deviate towards the lesion side when the mouth is opened
(-) jaw jerk reflex
if there is a unilateral UMN lesion, what happens with the jaw jerk reflex?
(-) jaw jerk reflex
due to bilateral innervation of the corticobrainstem tract, so one side is still intact
if there is a bilateral UMN lesion, what happens with the jaw jerk reflex?
(+) jaw jerk reflex
what is the special sensory fxn of CN 7 (facial nerve)?
afferents for taste from the anterior 2/3 of the tongue
what is the somatosensory fxn of CN 7 (facial nerve)?
afferents for sensation from the posterior ear canal
what is the parasympathetic fxn of CN 7 (facial nerve)?
efferent to lacrimal, nasal, and salivary glands except the parotid salivary gland
what is the motor fxn of CN 7 (facial nerve)?
efferents to muscles of facial expression and stapedius muscle
what is the reflex fxn of CN 7 (facial nerve)?
efferent limb of the corneal reflex
what is the most common CN 7 injury?
bell’s palsy
what is Bell’s palsy?
viral infection or immune disorder affecting CN 7
causes paralysis of muscles on one side of the face ipsilateral to the lesion (includes orbicularis oculi and frontalis muscles)
depression on the forehead ipsi to lesion (lack of frontalis)
no labial crease
droopy lips
if Bells’s palsy is severe, what symptoms may occur?
drooling, difficulty eating/drinking, dry cornea (lack of eyelid closing)
t/f: there is normal somatosensation in Bell’s palsy?
true
if somatosensation is in tact, what causes numbness in Bell’s palsy?
lack of muscle use
t/f: there is a loss of taste sensation in the anterior 2/3 of the tonguein Bells palsy
true
can autonomic fxns be affected in Bell’s palsy?
yes
if a pt has Bell’s Palsy and you ask them to close their eyes, what would you see?
the eyes roll back like normally but the ipsilateral eyelid doesn’t close
why is there no loss of sensation?
bc CN 7 is affected and this controls muscles, CN 5 is sensations
what are other causes of unilateral facial palsy?
Lyme disease
MS
cyst in the ear
tumor
trauma
Ramsey-Hunt syndrome (herpes zoster viral infection of CN 7 and 8)
what is facial muscle synkinesis?
caused by abnormal reinnervation of facial muscles
involuntary movements that accompany voluntary movements
if a pt has a CN 7 lesion and you ask them to close there eyes what would you see?
one eye won’t close
if a pt has a CN 7 injury and you ask them to smile, what would you see?
weakness on one side of the mouth
if a pt has a CN 7 injury and you try to make them laugh, what would you see?
same weakness affecting one side of the mouth as when asked to smile
if a pt has a corticobrainstem lesion and you ask them to close their eyes, what would you see?
both eyes close
if a pt has a corticobrainstem lesion and you ask them to smile, what would you see?
contralateral mouth weakness
if a pt has a corticobrainstem lesion and you try to make them laugh, what would you see?
more symmetric smile than when asked to smile
if a pt has a cingulate cortex lesion (emotional UMN) and you ask them to close their eyes, what would you see?
both eye close
if a pt has a cingulate cortex lesion (emotional UMN) and you ask them to smile, what would you see?
more symmetric smile than in response to trying to laugh
if a pt has a cingulate cortex lesion (emotional UMN) and you try to make them laugh, what would you see?
more weakness than when asked to smile
what are the 2 branches of CN 8 (vestibulocochlear nerve)?
auditory (cochlear) branch
vestibular branch
what is the role of the auditory (cochlear) branch of CN 8 (vestibulocochlear nerve)?
conscious and unconscious components
orient the eyes towards sound
conscious hearing
activates the entire NS
what is the role of the vestibular branch of CN 8 (vestibulocochlear nerve)?
VOR (gaze stability from the med vestibular tract)
VSR (postural stability from the lat vestibular tract)
what is the special sensory fxn of CN 8 (vestibulocochlear nerve)?
afferents for sense of head movement and head position
hearing
what is the reflex fxn of CN 8 (vestibulocochlear nerve)?
afferent for vestibulo-ocular reflex
where does the cochlear nuclei go to?
med geniculate body, inf colliculus, or reticular formation
what does the sup colliculus do?
orient eyes and head toward sound
what does the primary auditory cortex do?
conscious hearing
what does the reticular formation do?
activates the entire NS
what info is carried by the vestibular system?
position of the head in space relative to gravity
sudden changes in direction of head movement
the vestibular info is important for what 3 things?
1) motor control
2) spatial awareness
3) autonomic NS modulation
what are the 2 motor controls of the vestibular system?
VOR and VSR
what is the role of the VOR?
stabilization of the eyes (gaze stability)
what is the role of the VSR?
maintanance of postural stability
what are the peripheral components of the vestibular system? (KNOW THIS)
vestibular sensory receptors
CN 8
everything b4 the CN enters the BS
the ear
what are the central components of the vestibular system?
everything in the BS
4 vestibular nuclei
6 ascending/descending tracts
vestibulocerebellum (floculonodular)
vestibular cortex (in the parietal cortex of the R hemisphere)
where is the vascular supply for the vestibulocochlear apparatus from?
limited supply from the labyrinthine artery (small branch of the anterior inferior cerebellar artery)
t/f: vascular injury of the vestibulocochlear apparatus could mimic that of nerve injury
true
what are the 2 vestibular sensory receptors?
1) semicircular canals (SSC)
2) otoliths
what are the 3 semicircular canals (6 total)?
1) anterior
2) posterior
3) horizontal
what are the 2 otoliths?
1) saccule
2) utricle
which vestibular sensory receptors respond to rotational movement?
semicircular canals
which vestibular sensory receptors respond to linear movement?
otoliths
what movement does the saccule respond to?
vertical (elevator)
what movement does the utricle respond to?
horizontal (car)
what is an important sensory organ of the vestibular system?
the cupula!!!
when the head moves one way, what way does the fluid move?
in the opposite direction of the movement
when the head turns faster, is the stimulus stronger or weaker?
stronger
what is the composition of the crystals of the inner ear?
calcium carbonate
how are the SSC sensitive to gravity or acceleration?
the sensory receptors called the macula contains a unique membrane with crystals composed of calcium carbonate
what is the orientation of the horizontal canal?
30 deg from the earth
what are the functional pairs of the SCC?
HSCCs - horizontal SCCs pair
RALP - pairing of R ant and L post SCCs
LARP - pairing of L ant and R post SCCs
t/f: w/movement, one side is always excited when one is inhibited in the vestibular system
true
if the head turns R, which side will be excited? inhibited?
R excited
L inhibited
t/f: the superior and inferior division of the vestibular apparatus supply different parts
true (KNOW THIS)
is the superior or inferior division of the vestibular apparatus more susceptible to damage/virus?
the superior division due to anatomical phenomenon
what are the 6 output pathways of the vestibular nuclei
1) medial longitudinal fasciculus
2) medial vestibulospinal tracts (2) and lateral vestibulospinal tract (1)
3) vestibulocollic
4) vestibulothalamocortical
5) vestibulocerebellar
6) vestibuloreticular
what is the fxn of the lateral vestibulospinal tract? (KNOW THIS)
maintain balance and extensor tone (POSTURE)
where does the lateral vestibular nucleus receive afferent info from?
the vestibular labyrinth (particularly the utricle), cerebellum, and SC
what does the lateral vestibularspinal nucleus give rise to?
the lateral vestibulospinal tract (efferent arm)
what is the primary tract for vestibular influence on LMNs to postural muscles in the limbs and trunk?
the lateral vestibulospinal tract
what are the nuclei of the medial vestibulospinal tract?
the med and inf vestibular nuclei
t/f: the MVST extends ONLY to the cervical spine
true
what is the fxn of the MVST? (KNOW THIS)
controlling neck and head position
where does the MVST terminate?
bilaterally in the cervical region of the SC connecting w/motor neurons innervating the neck muscles
what are the actions of the MVST?
stable platform for eye movement and vision
mediating postural changes in response to head motion
what is the medial longitudinal fasciculus (MLF)?
tracts along the midline in both sides of the brainstem
the MLF connects the medial and superior vestibular nuclei to what 3 things?
the oculomotor nuclei
the accessory nuclei
the superior colliculus
what is the fxn of the MLF?
helps bring about coordinated movements of the head and eyes
moves eyes to maintain gaze stabilization during head movement
heart of the VOR
what are other inputs/outputs w/the vestibular nuclei?
vestibulocollic pathways
vestibulo-thalamo-cortical pathways
vestibular cerebellar pathways
vestibular reticular pathways
what is the vestibulocollic pathway?
afferent info from the cervical region to the nucleus of CN 11 (spinal accessory) to influence head position
what is the vestibulo-thalamo-cortical pathway?
provides conscious awareness of head position/movement and input to the corticospinal tracts (spatial orientation) from proprioceptive, tactile, auditory, and visual info
what is the vestibular cerebellar pathway?
influences eye movement and postural muscles
adjusts the “gain” or magnitude of responses to head movements or the vestibulo-ocular reflex (VOR)
responsible for vestibular adaptation
what is the vestibular reticular pathway?
excessive activity of the circuits linking vestibular nuclei, the reticular formation may result in autonomic changes (nausea, vomiting, and lightheadedness)
what is the role of the VOR? (KNOW THIS)
to allow for stable vision during fast head movements (gaze stability)
where is the best visual acuity available?
in the fovea of the retina (a very small area)
how does the VOR provide gaze stability?
eyes move equal and opposite of the head in a head:eye ratio/”gain” of 1 deg per sec in the opposite direction of the head movement
what happens is the head eye/ratio is slightly off of 1?
blurry vision
how is the VOR tested?
moving the head while focusing on a stationary object (read eye chart while moving the head)
what results from VOR dysfunction?
retinal slip causing dizziness and imbalance w/head movement
what is retinal slip?
VOR dysfunction where the eyes aren’t moving as fast as they should
what is Flouren’s law?
each canal is associated with a very specific eye movement when stimulated
what movement stimulates the anterior SCC?
tilting the head down
what movement stimulates the horizontal SCC?
turning the head R/L
what movement stimulates the posterior SCC?
tilting the head up
what 2 reflexes allow for gaze stabilization?
VOR (vestibulo-ocular reflex)
OPK (optokinetic reflex)
what is the VOR?
the use of vestibular info to stabilize the visual field and images during fast head movements
what is the OPK?
use of visual info to stabilize images during slow head movements
direction of gaze is achieved by what 3 things?
saccades
smooth pursuits
vergence movements
what are saccades?
fast eye movements that switch gaze from one object to another
what are smooth pursuits?
slow eye movements that follow a moving object
what are vergence movements?
movements of the eyes to adjust for different distances bw the eyes and a target
what are the 4 functions of the vestibular system?
1) subjective awareness of body position and movement in space (spatial orientation)
2) postural tone and equilibrium (posture of head and body)
3) stabilization of eyes in space during head movements (coordination of head and eye movements)
4) indirect effects on consciousness and autonomic fxns
what are the main consequences of vestibular system lesions?
vertigo (nystagmus)
impaired vision
impaired balance
gait “ataxia”
what is the most common symptom of a vestibular lesion in acute vestibular disorder?
vertigo (nystagmus)
what is vertigo?
the illusion of movement
are symptoms present all the time in acute or chronic vestibular disorder?
acute
are symptoms only present with movement in acute or chronic vestibular disorder?
chronic
what is a common visual disturbances in vestibular disorder?
oscillopsia or visual blurriness
is gait ataxia in vestibular disorder cerebellar or sensory ataxia?
neither, it is perceived discontrol that is sometimes called ataxia
what are the secondary consequences of vestibular lesions?
autonomic symptoms (nausea, vomiting)
limbic symptoms (anxiety, fear)
cognitive symptoms (lightheadedness, dizziness, decreased concentration)
what is nystagmus?
alternating slow and fast phases of eye movements
beating of the eyes
when would one experience normal physiologic nystagmus?
after spinning around
what are the 2 types of pathologic nystagmus?
spontaneous nystagmus
simple nystagmus
what does nystagmus look like?
the strong side pushes the eyes to the weak side and then quickly brings them back to the stronger side
what are the 3 pure directions of simple nystagmus?
1) linear (horizontal)-horizontal SCC
2) torsional-vertical SCC
3) vertical-BS dysfxn
what is the red flag direction of nystagmus?
vertical (upbeating/downbeating)
is pure vertical and direction changing nystagmus indicative of central or peripheral nystagmus?
central
is fatiguable nystagmus that habituates indicative of central or peripheral nystagmus?
peripheral
what are the characteristics of peripheral lesion (inner ear)?
delayed onset nystagmus
habituation
horizontal/rotary nystagmus
nystagmus doesn’t change directions
nystagmus is prominent only if vertigo is also present
what are the characteristics of central lesion (BS or cerebellum)
immediate/delayed nystagmus
no habituation
horizontal, rotary, or vertical nystagmus
nystagmus may change directions
prominent nystagmus may occur in the absence of vertigo
