Review Cranial Nerves Flashcards
CN I
olfactory
-SVA - smell
olfactory bulb
where CN I synapses
anosmia
complete loss of smell
CN I lesion
CN I lesions
trauma - frontal lobe
sliding on cribriform plate shears the nerves
CN II
optic nerve
-SSA - vision
CN II problems
alterations in vision
change in intracranial pressure
testing CN II
fundoscope
visual field exam
pupillary light reflex
in by 2 out by 3
can also test CN II
papilledema
increased ICP
CN III
oculomotor
GSE - 5 of 7 extraocular eye muscles
GVE-P - to intraocular eye muscles (ciliary muscle and sphincter pupillae)
course of CN III
oculomotor and edinger westphal nuclei
-travel through superior orbital fissure
-superior division - superior rectus and levator palpebrae superioris
inferior division - medial rectus, inferior rectus, inferior oblique, and motor to ciliary ganglion
testing CN III
extraocular eye movements
make the “H”
accomodation reflex
in by 2, out by 3
CN III lesion pathology
- uncal hernations
- cavernous sinus pathology
- aneurysm of posterior cerebral or superior cerebellar aa
- compression against temporal bone - increased ICP
- diabetic neuropathy
arteries near CN III
posterior cerebral a
superior cerebellar a
increased ICP
all cranial nerves can be affected
mostly CN II first
CN III lesion symptoms
paralysis extraocular - down and out
ptosis - cannot elevate eyelid
-paralysis sphincter - no pupil light reflex
-paralysis ciliary - no accomodation
cross section of CN III***
GSE - located centrally
GVE-P - fibers located peripherally
therefore, GVE-P affected first***
compression injuries of CN III***
damage to GVE-P
-loss of pupil constriction presents first
diabetic neuropathy in CN III***
sparing of GVE-P but GSE loses blood supply
pupillary sparing***
CN IV
trochlear nerve
GSE - superior oblique
course of trochlear nerve
only one to exit dorsal surface
-superior orbital fissure
innervates superior oblique
test CN IV
adduct eye and look down
-lesion cannot do this
extraocular movements
lesion to CN IV
neutral position - neutral position slightly elevated and adducte
CN V
trigeminal nerve
SVE - arch 1 derivatives
GSA
arch 1 derivatives
muscles of mastication
CN V innervation
temporalis masseter M/L pterygoid anterior belly digastric mylohyoid tensor tympani tensor veli palatini
GSA of trigeminal
face teeth oral cavity external ear paranasal sinuses nasal cavity eye and conjunctiva dura
course of trigeminal nerve
sensory and motor nucleus
-trigeminal ganglion
gives off:
V1 - superior orbital fissure
V2 - foramen rotundum to PPF
V3 - foramen ovale to infratemporal fossa
V3
only one carrying the motor portion**
branches of trigeminal
route to distribute the autonomics
ophthalmic nerve
V1
- sensory to eye
- suspends ciliary ganglion
- supplies upper dermatome of face
maxillary nerve
V2
- sensory root to PPG
- maxillary teeth
- nasal cavities and paranasal sinuses
- middle dermatome of face
- upper lip, nostril, temple
mandibular nerve
V3
- suspends otic ganglion and submandibular
- lower dermatome of face
testing CN V
test sensation to the face
-in each dermatome
can also test corneal reflex
corneal reflex
in by V1 (nasociliary branch)
out by VII
jaw jerk reflex
lightly tap mandible
-response - mm. mastication contract
afferent - V3
efferent - V3
symptoms of CN V lesion
hyperacusis - loss of SVE to tensor tympani
deviation of jaw to side of lesion***
loss of sensory to face
loss of corneal reflex
jaw towards or away from CN V lesion
towards lesion
CN VI
abducens
GSE - lateral rectus
course of CN VI
abducent nucleus
- superior orbital fissure
- innervates lateral rectus