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87 and 88: Cranial Nerves (Clinical Correlations (anisocoria (damaged side…
87 and 88: Cranial Nerves
Clinical Correlations
anisocoria
corneal injury
optic nerve injury
glaucoma
uveitis
retinal disease
congential
cancer
damaged side
no direct pupillary response
no consensual pupillary response
cranial nerves I, II, III, IV, VI
strabismus
divergent strabismus
ventrolateral strabismus
eye points down and out
pupil dilation in damaged eye
no PLR
no consensual light reflex
parasympathetic damage
oculomotor n. damage
when only 1 eye is affected
eyes point lateally
walleyed
damage
medial rectus m.
CN III oculomotor n
boston terriers
convergent strabismus
both eyes point medially
cross-eyed
damage
lateral rectus
CN VI abducen n
can be inherited
siamese cats
rotational/dorsolateral strabismus
CN IV trochlear damage
dorsal oblique m damaged
medial strabismus
eye is adducted
damage
lateral rectus muscle
CN VI abducen n
eye points medially
lesion of parasympathetic oculomotor nucleus
no PLR on damaged side
no consensual LR in damaged eye
pupil dilation in one or both eyes
dropped jaw
hearing assessment
vestibular disease
tongue paralysis/atrophy
facial paralysis
brainstem external (ventral view)
contains
ascending tracts
descending tracts
diencephalon
sensory relay
homeostasis
motor function
sleep-wake cycle
structures include...
pineal gland
superior branchium
inferior brachium
cerebral peduncle
oculomotor nerve
rostral colliculus
caudal colliculus
thalamus
sensory relay center
all sensory neurons projecting in the cerebrum first synapse here
nuclei connecting to
hippocampus
cingulate gyrus
medial and lateral geniculate nuclei
auditory pathway
visual pathway
one on each side of the brainstem
hypothalamus
ventral to thamali
regulates autonomic nervous system
pituitary gland extends from here
homeostasis
subthalamus
controlling motor functions
pacemaker for rhythmic movements
suppressing unwanted movements
epithalamus
emotional and visceral responses to odor
modulation of sleep-wake cycle
pineal gland
midbrain (mesencephalon)
relay visual and auditory info
contains
rostral and caudal colliculi
process and relaying visual and auditory info
cranial nerve nuclei
induce pupillary rstriction
orientation reflexes for vision and sound
pons
relay between forebrain and cerebellum
cranial nerve nuclei
sensory info from face
motor control of mastication
medulla (myelencephalon)
structures include...
olive
medullary pyramid
desuccation
cranial nerve nuclei
sensory
motor
functions
feeding
respiratory and cardio responses
vocalizatoin
cranial nerve origins
functions
breathing
swallowing
heart rate
blood pressure
consciousness
sleep
damage
CN signs
visual and hearing deficits
disorders of
thirst
appetite
temperature regulation
alternated level of consciousness
brainstem internal
4th ventricle
pushes cranial nerve sensory nuclei laterally
special senses
cerebellum
functions
smell
vision
taste
hearing
balance
reticular formation
functions
alertness
regulating visceral responses
micturtion
HR
respiration
movement
regulating muscle tone
reticulospinal tracts
wakefulness
consciousness
arousal
attention
pain perception
spinal reflexes
mixed grey and white matter
crosses pons and medulla
portions of extrapyramidal tracts
contains
red nucleus
projection neurons
projects to
rubrospinal tract
thalamus
rubrospinal tract
quadrupedal gait
voluntary movement of proximal limb mm.
head movements
damage
coma
cardiovascular issues
sleep/wakefulness disorders
lack of some voluntary movement
cranial nerves (organized according to cranial to dorsal locations
whew
III* oculomotor
midbrain
tests*
horizontal, rotational, and lateral eye movements*
damage
ventrolateral strabismus
dilated pupil*
PLR*
consensual light reflex
= applies to IV and VI as well
lesions
lesion of the optic chiasm
severe head trauma
trauma to the retinas
check consciousness
bilateral mydriasis
oculomotor nerve
parasymapthetic dysfunction
ventrolateral strabismus
retina or optic nerve = anisocoria
motor to
3 recti
ventral oblique
levator palpebrae
parasympathetic to the pupil
damage = dilated pupil
II optic
diencephalon
tests
menace response
pupillary light reflex
blink response
damage = loss of vision (anopsia)
pathway = retina > optic nerve > optic chiasm > optic tract > thalamus > visual cortex
lesion of a retina or optic nerve = anisocoria
lesion of the optic chiasm = bilateral mydriasis
IV* trochlear
midbrain
damage = rotational/dorsolateral stabismus
motor to 1 eye m. (dorsal oblique)
V trigeminal
enters and exits pons
tests
tickle face
pinch lip
assess jaw tone
corneal reflex
sensory zones
ophthalamic n.
maxillary n.
mandibular n.
dropped jaw
sensory from face
motor to mastication mm.
massenter
temporalis
pterygoids
tensor veli palpebrae
tensor tympani
VI* abducens
medulla
damage = medial strabismus
motor to 1 eye muscle (lateral rectus)
VII facial
enter and exit medulla
motor to
facial mm.
external ear
inner ear (stapedius)
mm to hyoid/ventral neck
test
observe drooping lip or ear
blink reflex
damage
facial paralysis
dry eye
dry nose
may only affect one side
sense of taste
VIII vestibulocochlear
enters medulla
balance and hearing
test
observe
eye movements
head position
balance issues
hearing tests
damage
head tilt
ataxia
circling
head sway
deafness
nystagmus
positional
vertical
sensorineural
cochlea
hair cells
coclear n.
conductive
tympanic membrane
ear drum
ossicles
innervates
semicircular canals
vestibule
cochlea
IX* glossopharyngeal
medulla
= shared with X vagus
test*
swallowing
gag reflex
damage*
swallowing issues
aspiration pneumonia
coughing
vocalization changes
motor to some pharynx mm
sensory from
tongue
palate
pharync
carotid body
carotid sinus
X* vagus
enters and exits medulla
parasympathetic to cervical, thoracic, abdominal viscera
motor to
larynx
pharynx
upper esophagus
taste
XI accessory
exits medulla and spinal cord
motor to a few neck mm
cleidocephalicus
omotransversarius
trapezius
sternocephalicus
spinal and brain stem roots
may contribute to vaus
difficult to evaluate
XII hypoglossal
exit medulla
motor to tongue mm.
genioglossus
hyoglossus
test
licking response
ability to eat and drink
damage
tongue paralysis
tongue atrophy
deviation to affected side
I olfactory
olfactory
damage = anosmia
test = owner evaluation
cerebrum