Cross Species - Cranial Nerves Part 1 Flashcards
what is the name & function of cranial nerve I?
olfactory nerve - smell
what is the name & function of cranial nerve II?
optic nerve - vision, afferent fibers to the brain
what is the name & function of cranial nerve III?
oculomotor nerve -
motor to the iris - parasympathetic fibers cause constriction
motor to most muscles of the eye - except for those innervated by CN IV/CN VI
what is the name & function of cranial nerve IV?
trochlear nerve - motor to the dorsal oblique muscles of the eye
what is the name & function of cranial nerve V?
trigeminal nerve - all 3 branches provide sensation to the face/oral cavity/corneal surface of the eye/ear
mandibular & maxillary branches - motor to the muscles of mastication
what is the name & function of cranial nerve VI?
abducens nerve - motor to the lateral rectus & retractor bulbi muscles of the eye
what is the name & function of cranial nerve VII?
facial nerve
motor to the muscles of facial expression
taste on the rostral 2/3 of the tongue & sensation of the concave pinna
parasympathetic fibers to the nasal glands, lacrimal glands, mandibular salivary glands, & sublingual salivary gland
what is the name & function of cranial nerve VIII?
vestibulocochlear nerve
vestibular part - balance, posture, equilibrium, & muscle tone
cochlear part - hearing
what is the name & function of cranial nerve IX?
glossopharyngeal nerve
sensory & motor to the pharynx & larynx
taste on the caudal 1/3 of the tongue
parotid & zygomatic salivary glands
what is the name & function of cranial nerve X?
vagus nerve
sensory & motor to pharynx & larynx
sensation of the external ear canal
sensory & motor to the thoracic/gastrointestinal viscera
what is the name & function of cranial nerve XI?
accessory nerve
motor to the trapezius, sternocephalic, & brachiocephalic muscles
what is the name & function of cranial nerve XII?
hypoglossal nerve
motor to the tongue, sternohyoideus, & sternothyroideus muscles
how is cranial nerve I tested?
may test by noting animal’s response to treats or certain chemicals
difficult to asses
what are the ways in which you can test the function of cranial nerve II?
PLR test
menace response
visual tests - obstacle courses, tracking objects with the eyes
nerve fibers decussate at the optic chiasm (amount varies by species)
what are the ways in which you can test the function of cranial nerve III? what will you see with damage/abnormality?
PLR
if abnormal, look for the presence of ptosis of ventrolateral strabismus
what are the ways in which you can test the function of cranial nerve IV? what will you see with damage/abnormality?
really only going to look for injury causing lateral rotation of the globe
what are the ways in which you can test the function of cranial nerve V? what will you see with damage/abnormality?
palpebral reflex
palpate the nasal mucosa or auricular lining & look for a reaction
if mandibular or maxillary branch is damaged - atrophied muscles of mastication
what are the ways in which you can test the function of cranial nerve VI? what will you see with damage/abnormality?
corneal reflex - looking for retraction of the globe & prolapse of nictitans while keeping the eyelids open
with injury - medial strabismus
what are the ways in which you can test the function of cranial nerve VII? what will you see with damage/abnormality?
menace response
palpebral reflex
tickle ear/nose & watch for a reaction
test parasympathetic function with the schirmer tear test
classic abnormal appearance - unilateral droopy lip/ear/eye, & dry eye
what are the ways in which you can test the function of cranial nerve VIII? what will you see with damage/abnormality?
vestibular - with unilateral injury, see a head tilt towards the lesion, circling/falling towards the lesion, spontaneous nystagmus with the fast phase away from the lesion, & ventral strabismus when the nose is elevated
cochlear part - brainstem auditory evoked response or assessing response to loud sounds
what are the ways in which you can test the function of cranial nerve IX? what will you see with damage/abnormality?
difficult to assess separately apart from CN X
damage causes dysphagia
what are the ways in which you can test the function of cranial nerve X? what will you see with damage/abnormality?
look for dysphagia, laryngeal paralysis, & dysphonia
in ruminants - vagal indigestion
what are the ways in which you can test the function of cranial nerve XI? what will you see with damage/abnormality?
atrophy of the trapezius, sternocephalicus, & brachiocephalicus muscles
what are the ways in which you can test the function of cranial nerve XII? what will you see with damage/abnormality?
look for atrophy, weakness, or deviation of the tongue
what are the 3 branches of major importance of cranial nerve V?
mandibular, ophthalmic, & maxillary branches of the trigeminal nerve
what cranial nerves are tested by the PLR?
CN II is afferent
CN III is efferent - when looking at the oculomotor nerve, the efferent aspect of CN III is parasympathetic
what cranial nerves are tested by the menace response?
CN II is afferent
CN VII is efferent
what cranial nerves are tested in the palpebral reflex?
CN V is afferent
CN VII is efferent
what cranial nerves are tested in the corneal reflex?
CN V is afferent
CN VI is efferent
what cranial nerve is assessed by the schirmer tear test?
parasympathetic part of cranial nerve VII
what two muscles of the eye are not innervated by cranial nerve III? what cranial nerves innervate them?
dorsal oblique muscle - trochlear, cranial nerve IV
lateral rectus & retractor bulbi muscles - abducens, cranial nerve VI
