Cranial Nerve Function & Testing Flashcards
What are the 12 paired cranial nerves
- I – Olfactory nerve
- II – Optic nerve
- III – Oculomotor nerve
- IV – Trochlear nerve
- V – Trigeminal
- VI – Abducent nerve
- VII – Facial nerve
- VIII – Vestibulocochlear nerve
- IX – Glossopharyngeal nerve
- X Vagus nerve
- XI – Accessory nerve
- XII – Hypoglossal nerve
what is the function of CN I
olfactory nerve
conscious perception of smell
where do axons of CN I pass from
from the cell bodies on the ethmoturbinates through the cribiform plate to the olfactory bulb
what does clinical dysfunction of CN I look like
hyposmia or anosmia
difficult to detect
inappentance
how can CN I be clinically evaluated
response of animal to aromatic substance while blindfolded
where does the CN II run
optic nerve
what does the CN III innervate
oculomotor nerve
innervates ipsilateral dorsal, ventral, and medial recti muscles and ventral oblique
efferent arm of the pupillary light reflex
what are the clinical dysfunction of CN III
ventrolateral strabismus
dilated unresponsive pupil
how is the CN III evaluated
eye position
pupillary light reflex
where does the CN IV innervate
contralateral dorsal oblique muscle
what are the clinical dysfunction of CN IV
dorsolateral strabismus of contralateral eye
best evaluated by examining fundus
in cats will see altered pupil orientation
what does the CN V innervate
sensory innervation of face (cornea, mucosa of nasal septum and oral cavity)
motor innervation of masticatory muscles
what are the 3 branches of CN V
ophthalmic, maxillary, mandibular
what are the clinical dysfunction
masticatory muscle atrophy
decreased jaw tone
loss of facial sensation
how is the CN V clinically evaluated
size and symmetry of muscles
jaw tone
corneal reflex
palpebral reflex
nasal stimulation
what does the CN VI innervate
innervates ipsilateral lateral rectus
innervates retractor bulbi
what are the clinical dysfunctions of CN VI
ipsilateral convergent strabismus
loss of physiological nystagmus
inability to retract eyeball
how is CN VI evaluated
corneal reflex
assess vestibular ocular reflex
what does the CN VII innervate
motor function to muscles of facial expression
sensory to rostral 2/3 of tongue
parasympathetic component innervates lacrimal and mandibular and sublingual salivary glands
the facial nerve courses through the middle ear
how is CN VII clinical dysfunction acutely identified
ipsilateral drooping of ear and lip
absence of blinking
kerratoconjunctivitis sicca if lesion between medulla and middle ear
how is CN VII clinical dysfunction chronically identified
lip is retracted
what is the clinical evaluation of CN VII
palpebral reflex (CN V and CN VII)
menace response (CN II and CN VII)
lip pinch (CN V and CN VII)
schirmer tear test
what is the function of CN VIII
hearing via the cochlear nerve which transmits impulses from organ or Corti to brainstem
vestibular function which adapts position of eye and body with respoect to position and movement of head
vestibular nerve transmits impulses from vestibular apparatus to the vestibular nuclei in the brainstem
what is the clincal dysfunction of CN VIII
head tilt
falling/rolling
nystagmus
strabismus
ataxia
deafness
how is CN VIII clinically evaluated
evaluation of body and head posture
vestibulo-ocular reflex ‘physiological nystagmus’
BAER test for hearing
what are the functions of CN IX and X
shared sensory (nucleus solitarius) and motor (nucleus and ambiguous) nuclei
innervates pharynx and palate
parasympathetic component innervates parotid and zygomatic salivary glands
vagus controls motor function of larynx, pharynx and esophagus
parasympathetic component innervates thoracic and abdominal viscera
what are the clinical dysfunction
dysphagia
absent gag reflex
inspiratory dyspnoea
dysphonia
megaesophagus
what are the clinical evaluation of CN IX and X
gag/swallow reflex
what does CN XI innervate
innervation to trapezius and part of sternocephalicus and brachiocephalicus muscles
what is the clinical dysfunction CN XI
deviation of neck
what does CN XII innervate
innervation to the tongue
what is the clinical dysfunction of CN XII
atrophy or deviation of tongue
problems with prehension and deglutition
how is CN XII clinically evaluated
tongue tone
tongue position
