Cranial Nerves Flashcards
CN I
olfactory
CN I location of cell bodies
olfactory organ
receptor cells in olfactory epithelium
CN I pathway
receptor cells in olfactory epithelium =>
cribiform plate of ethmoid bone =>
olfactory bulb
CN I function
SVA - sense of smell
CN I exam
test w several different familiar odors
what CN is associated with loss of taste over aging?
CN I
what are causes of anosmia (olfactory loss)
head trauma
viral infection
intracranial lesions
nasal obstruction
what can occur with fracture of the cribiform plate?
CSF leakage through nose
CN II
optic nerve
CN II location of cell bodies
retina
CN II pathway
optic canal => fibers cross at optic chiasm => optic tracts => thalamus => optic radiations => primary visual cortex
CN II function
SVA, sight
a tumor of what organ can cause compression of CN II?
pituitary gland
CN II exam
blink response, pupillary light reflex, peripheral vision
CN III
oculomotor n
CN III location of cell bodies
midbrain
What is transmitted through Edinger-Westphal nucleus?
parasympathetic fibers of CN III (oculomotor n.)
CN III pathway
midbrain =>
pierces dura lateral to diaphragma sellae =>
runs in lateral wall of cavernous sinus =>
enters orbit via superior orbital fissure
CN III function (GSE)
motor innervation to superior, medial and inferior recti and inferior oblique and levator palpebrae superioris ms
(eye & eyelid movement)
what muscles are innervated by the superior division of CN III? what do they do?
superior rectus (look towards ceiling) levator palpebrae superioris (raise eyelid)
what muscles are innervated by the inferior division of CN III? what do they do?
inferior & medial recti (look down/medially)
inferior oblique superioris (external rotation and abduction of eye
what condition in characterized by a fixed down and out position of the eye and what cranial nerve is involved?
oculomotor palsy
CN III
what sxs are associated w/ oculomotor palsy?
strabismus
double vision (diplopia)
ptosis
midriasis (pupil dilation)
CN IV
trochlear n
what is the only cranial nerve that exits the midbrain dorsally?
CN IV
CN IV pathway
exits dorsal surface of midbrain =>
pierces dura mater =>
run in lateral wall of cavernous sinus =>
enters orbit via superior orbital fissure
CN IV function
GSE - motor innervation to superior oblique m.
=> abduction, depression and medial rotation of eye
CN VI
abducens
CN VI location of cell bodies
midbrain
CN VI pathway
emerges btwn pons and medulla => crosses pontine cistern => pierces dura covering clivus => runs in cavernous sinus near ICA => enters orbit via superior orbital fissure
CN VI function
GSE - motor innervation to lateral rectus
=> abduction of the eye
CN IV palsy sxs
eyes crossed, double vision
head tilted away from affected side to compensate
can’t look medially (ie reading)
CN VI palsy
double vision
can’t look laterally
CN VI exam
have pt abduct eye
CN IV exam
have pt adduct eye then look down
CN V
trigeminal n
CN V location of cell bodies
pons
CN V pathway
emerges from pons laterally =>
ganglion in trigeminal cave, lateral to cavernous sinus
what are the three branches of CN V
ophthalmic (V1)
maxillary (V2)
mandibular (V3)
CN V1 pathway and function
cavernous sinus => exits skull via superior orbital fissure => GSA to superior face and scalp
CN V2 pathway and function
cavernous sinus => exits skull via foramen rotundum => GSA to nose upper jaw
CN V3 pathway and function
exits skull via foramen ovale => GSA to sides of face and mandible
CN V function (SVE and GSA)
motor to ms. of mastication
sensory to face and scalp
CN V1 examination
corneal reflex - touch cornea w/ cotton
sensation of forehead & nose
CN V2 examination
sensation of cheeks
CN V3 examination
sensation of chin
ability to chew
in what condition can trigeminal dermatomes be affected?
herpes zoster
CN VII
facial nerve
CN VII location of cell bodies
midbrain
CN VII pathway
emerges from pontine-medularry jxn => traverses posterior cranial fossa => exits skull vis internal acoustic meatus=> runs in facial canal => exits via stylomastoid foramen => passes through parotid
CN VII function (SVE)
motor to ms. of facial expression
CN VII function (GVE)
parasympathetic innervation to lacrimal, nasal and palatine glands
submandibular & sublingual salivary glands
CN VII function (SVA & GSA)
taste to anterior tongue
sensation to external acoustic meatus
terminal branches of facial nerve
posterior auricular temporal zygomatic buccal marginal mandibular cervical
what cranial nerve is implicated in Bell’s palsy
CN VII, facial n
what are the sxs of Bell’s palsy
cannot blink
drooling
CN VIII
vestibulocochlear n
CN VIII function
SSA - hearing and equilibrium
sxs associated w/ CN VIII
tinnitus off balance nystagmus deafness acoustic neuroma
what is rombergs sign and what CN does it test?
pt falls when feet are together, arms at sides, eyes closed
CN VIII lesion
what CN lesion is associated w/ nystagmus
CN VIII
what CN is evaluated in Weber’s test?
CN VIII
CN IX
glossopharyngeal
CN IX location of cell bodies
medulla
CN IX pathway
medulla => exits skull via jugular foramen =>
passes btwn superior & middle pharyngeal constrictors => oral cavity
CN IX function
sensation from ear, posterior tongue, taste to posterior tongue, sensory from oropharyx & carotid body PNS to parotid motor to stylopharyngeus ms.
CN X
vagus n
CN X pathway
medulla => exits skull via jugular foramen
CN X function
sensation from dura, ext. auditory canal, viscera, pharynx, larynx
taste from epiglottis
PNS to viscera
motor to pharynx, larynx, palatine ms.
CN X testing
swallowing reflex
hoarseness
deviation of uvual when saying AH
CN XI
spinal accessory
CN XI function
motor to SCM & traps
CN XI pathway
spinal cord => enters crainium via foramen magum => exit skull via jugular foramen
CN XI testing
shrug against resistance (traps)
turn head against resistance (SCM)
CN XII
hypoglossal n
CN XII function
motor to tongue ms
styloglossus
hypoglossus
genioglossus
CN XII pathway
medulla => exits skull via hypoglossal canal => travels w cervical plexus => crosses occipital a => enters oral cavity
CN XII testing
protruded tongue deviates to side of lesion
