cranial nerves Flashcards
decrease in bilateral constriction when light is shone in affected eye vs unaffected eye is due to
afferent pupillary defect: optic nerve damage or severe retinal injury
called a Marcus Gunn pupil
diminshed or no pupillary light reflex in affected eye (direct and consenual) is due to
efferent pupillary defect: CN3 (oculomotor n.) damage due to compression from PCA aneurysm or uncal herniation
inner part of CN 3 includes
motor fibers for EOM, levator palpebrae
susceptible to ischemia from diabetes: glucose → sorbitol
outer part of CN 3 includes
parasympathetic fibers for pupillary light reflex
susceptible to compression
ptosis + down + out gaze due to
ischemia damage to CN3 (inner part of nerve)
lateral rectus m. innervated by
CN 6
superior oblique m. innervated by
CN 4
all the rest of EOM’s innervated by
CN 3
what is the lesion? eye looks down + out ptosis pupillary dilation loss of accommodation
CN 3 damage
eye looks upward especially with contralateral gaze (problems going down stairs)
head tilt toward side of lesion
CN 4 damage
eye looks medially
no abduction
CN 6 damage
bitemporal hemianopsia due to lesion at
optic chiasm
L or R homononymous hemianopsia due to lesion at
contralateral optic tract
L or R anopsia due to lesion at
optic nerve (CN 2)
macula lesion due to
macular degeneration
L or R homonymous hemianopsia + macular sparing due to lesion at
contralateral PCA infarct
nerve that provides touch to anterior 2/3 of tongue
mandibular branch (V3) of CN 5
nerve that provides taste to anterior 2/3 of tongue
facial nerve (CN 7)
nerve that provides touch to posterior 1/3 of tongue
glossopharyngeal nerve (CN 9)
nerve that provides taste to posterior 1/3 of tongue
glossopharyngeal nerve (CN 9)
nerve that provides taste to epiglottis
vagus nerve (CN 10)
paralysis of ISPSILATERAL side of ENTIRE face caused by this lesion (smile droop + can’t close eye)
facial nerve (CN 7)/nucleus lesion (Bell’s palsy)
paralysis of ISPSILATERAL side of ENTIRE face caused by this lesion
facial nerve (CN 7)/nucleus lesion (Bell’s palsy)
paralysis of CONTRALATERAL side of LOWER face caused by this lesion
facial motor cortex lesion (stroke)
if able to raise forehead + eyebrows - r/o facial nerve (CN 7) palsy
facial motor cortex receives motor fibers for the LOWER face only from the CONTRALATERAL cortex but receives motor fibers for the UPPER FACE from BOTH cortices
CONTRALATERAL uvula deviation due to lesion of
vagus nerve (CN 10) or nucleus ambiguus (medulla lesion) levator veli palatini m. not elevating the palate on the side of the nerve lesion so uvula deviates in opposite direction (only side pulling up on palate)
IPSILATERAL tongue deviation when sticking out due to lesion of
hypoglossal nerve (CN 12)/nucleus "LICK THE WOUND"
IPSILATERAL tongue deviation when sticking out due to lesion of
hypoglossal nerve (CN 12)/nucleus "LICK THE WOUND" - like a wheelbarrow
motor neurons of vagus nerve (CN 10) originate in
nucleus ambiguus in medulla
functions of nucleus ambiguus
swallowing + speech + palate elevation
nucleus ambiguus in medulla receives input from BOTH motor cortices via corticobulbar tracts
lesion in L or R motor cortex above nucleus ambiguus WON’T cause uvula deviation
each hypoglossal nuclei receive input from BOTH motor cortices
lesion in L or R motor cortex above hypoglossal nuclei WON’T cause tongue deviation
findings with cavernous sinus infection
CN 3: down + out eye CN 4 CN 6: can't abduct eye CN 5 (V1,V2): pain + numbness in face diplopia
findings with cavernous sinus syndrome due to infection
CN 3: down + out eye
CN 6: can’t abduct eye - most common (most medial)
CN 5 (V1,V2): pain + numbness in face
diplopia
salivation of parotid gland
CN 9
salivation of sublingual and submandibular gland
CN 7
hypoxia measured by carotid body
CN 9
blood pressure from carotid sinus
CN 9
blood pressure from aortic arch
CN 10
