cranial nerves Flashcards
where are the cell bodies of CN 5-10 and 12
brainstem
- 5 ( exit pons)
- 6-8 (exit pontine medullary jxn )
- 9 10 12 (exit medulla)
what is the function of trochlear nerve (CN 4)
GSE- motor innervation to superior oblique
adducts eye and looks down
what is bells palsy
affected facial nerve means you can’t really move the side of the face with the affected nerve
what are the 3 branches associated with trigemainl nerve
V1- ophthalmic
-passes cavernous sinus and enters orbit via the superior orbital fissure
V2- maxillary
-passes the cavernous sinus and exits the foramen rotundum
V3-mandibular
-exits the foramen ovale
function of glossopharyngeal nerve (CN 9)
GSA: (skin sensation) from ear and external auditory canal, and posterior 1/3 of tongue
GVA: (visceral sensation) from oropharynx and carotid body
SVA: taste from posterior 1/3 tongue
GVE: PNS to parotid gland
SVE: motor to stylopharngeus m. (arch 3 )
what are the branches off CN 7 that split in the facial canal
- chorda tympani (taste and PNS to submandibular and sublingual glands)
- stapedius (ear)
- PNS to lacrimal (greater petrosal N.)
what nerves exit the jugular foramen ? why is this important ?
9, 10, 11 (glossopharyngeal, vagus, and spinal accessory)
-TUMOR here can compress all of these and causes symptoms of each
what is the function of oculomotor (CN 3)
*eyeball and eyelid movement
GSE-motor innervation to superior/middle/inferior recti, inferior oblique, and elevator palpebrae
(visual tracking and fixation of eye)
GVE- motor PNS innervation to pupil and ciliary muscles
(constricts pupil and contracts ciliary muscles (lens) for accommodation of sight)
olfactory n. tract
cribriform plate to olfactory bulbs
*synpase in the bulbs
tract of CN 9
emerges medulla and exits jugular foramen to pass between superior and middle pharyngeal constrictors and enter oral cavity
what happens if you cut CN8? compress CN 8? or a tumor on CN 8?
cut: deafness
compress: tinnitus, vertigo, nystagmus
tumor: acoustic neuroma can affect facial nerve and cause bells palsy
what is the function of V2 (maxillary branch) of C5
only sensory (GSA) -sensation from the skin of the face, lower eyelid, cheek, upper lip, maxillary teeth, mucosa of nose (line the nasal cavity in nose) , maxillary sinus
t/f
olfactory film can be sheared off at the cribriform plate during a head injury and there is a gradual loss of smell as you age
true
what does the blink reflex test
optic and facial nerves (CN 2 and 7)
- afferent (sensory) to see: optic
- efferent (motor) to close eyelid : 7
function of spinal accessory N. (11)
GSE: motor to SCM and trapezsius
TEST this muscles with resistance from assessment
tract of CN 8
2 branches
- vestibular nerve- innervates the utricle and saccule
- cochlear- innverates the cochlea
- enter skull via the internal acoustic meatus to enter brainstem at pontine medullary jxn
what is the tract of the chorda tympani
come from facial nerve before the stylomastoid foramen and crosses the tympanic cavity and passes through the petrotympanic fissure to join the linguinal nerve. synapses in submandibular ganglion and supplies taste and PNS to glands
GVE nerves (organ motor)
(autonomics- PNS)
3 7 9 10
how to asses the function of the cochlear division of CN 8
- Rhinne test (tuning fork on mastoid to asses AC to BC) normally AC > BC; conduction deafness BC>AC; nerve deafness AC = BC
- Weber test
-sound laterlizes to bad ear if conduction deafness,
opposite ear if nerve damage
how do you asses the function of the vestibular division of CN 8
(responsible for position of head in space)
- Rombergs sign (balance test with eye closes)
- past pointing (finger to nose test)
- nystagmus (looking for abnormal saccades )
where are the cell bodies of CN 1 and 2
forebrain
2- dicephalon
what are your special senses
taste, smell, sound, balance and sight
(ear and eyes are somatic SSA)
(nose and mouth are visceral SVA)
what does the corneal reflex test
CN 5 and 7 (trigeminal and facial)
- sensory (5): touch of cornea
- motor (7): closes eyelid
- touch cornea with ball of cotton.
- contanct lease wearers have suppressed this reflex
function of hypoglossal nerve (CN 12)
GSE: motor to tongue muscles
TEST with tongue profusion test (deviates to same side as affected side)
what is the tract of the trigeminal nerve
emerges from lateral pons and synapses in trigeminal ganglion located in the trigeminal cave lateral to the cavernous sinus
SSA and SVA (sensory)
SSA- 8 (hearing) 2 (sight and balance)
SVA- 7 9 10 (taste) 1 (smell )
tract of vagus n.
exits medulla and passes jugular foramen
what is the function of V1 (ophthalmic branch) of CN 5
only sensory ( GSA) -sensation from the cornea, and skin of forehead, scalp, upper eyelid, bridge to point of nose (not sides of nose)
an aneurysm of the Internal carotid artery can affect what
can compress the optic chasm and affect sight
what tests asses cranial nerve 7
- taste
- wrinkle forehead, close eyes, blow, whistle, smile, suck on straw
- blink reflex
- corneal reflex
tract of the oculomotor nerve
leaves the midbrain and pierces the dura lateral to the diaphragma sellae where it runs in the lateral wall of the cavernous sinus and enters the orbit via the superior orbital fissure
SVE nerves (special organ motor)
*muscles from pharyngeal arches
5, 7, 9, 10
tract of CN 2 (optic)
arises from ganglion cells in retina and exit the orbit in the optic canal to go to the middle cranial fossa (with the optic chasm) where most fibers then go to end in the lateral geniculate bodies of the thalamus
where does the PNS to the lacrimal gland join the deep petrosal N.? what does it form ?
at the foramen lacerum
-forms the nerve of the pterygoid canal
-synpases in pterogopalatine ganglion
functions of vagus n. (CN 10)
GSA: skin sensation from external auditory canal and dura
GVA: sensory from pharynx, larynx, aortic arch, epiglottis, bass of tongue,
SVA: taste from epiglottis
GVE: PNS to viscera
SVE: motor contractors to pharynx, palatine muscles, and intrinsic muscles of larynx (arches 4 and 6)
what is the tract of abducens nerve
from brainstem (at jxn) it then transverses the pontine cistern, pierces the dura covering the cloves, runs in the cavernous sinus near the ICA, and enters the orbit via the superior orbital fissure
function of vestibulocochlear nerve
SSA: hearing and equilibrium
where are the cell bodies of CN 3 and 4
midbrain
how to test the function of trigeminal nerve
V1 - sensation (forehead and nose) ; or Corneal reflex
V2- sensation of cheek
V3- sensation of chin, motor muscles of chewing
what is anosmia
olfactory loss (no longer can smell)
- contralateral nostril can compensate for unilateral anosmia
- caused by head trauma, viral infections, lesions, nasal passage obstruction
what is the facial nerve (CN 7) tract
***** UPDATE
exits the pontine-medullary junction to cross the posterior cranial fossa and run in the facial canal where it splits:
- stapedius - goes to ear exiting the internal acoutisc meatus
- chorda tympani
- greater petrosal N.
tract of CN 11
from spinal cord enters through foramen magnum and exits jugular foramen
where are the cell bodies of CN 11 (spinal accessory)
spinal cord
GSE nerves (muscle motor)
3, 4 ,6, 12
GVA nerves innervate muscles from
endoderm or mesoderm adjacent to endoderm
GSA nerves innervate muscle from
ectoderm or mesoderm adjacent to Ectoderm
function of cranial nerve 6 (abducens)
GSE: motor innervation to the lateral rectus in the orbit
abducts eye
what is CSF rhinorrhea
fracture of the cribriform plate (associated with CN 1) causes CSF to leak through nose.
rhinorrhea (runny nose)
**halo sign
(clear drainage separates from bloody drainage and the blood goes to the center with the CSF around the outside
what is trigeminal neuralgia (tic douloureux)
irritation to the trigeminal nerve or its branches that causes severe pain from even mild face stimulation (like brushing teeth or putting makeup on) and possible suicidal thoughts
-can be from nerve compression or idiopathic injury
what does the H test asses
cranial nerves 3, 4, 6,
cavernous sinus thrombosis involves what 3 CN nerves
3,4,6
oculomotor
trochlear
abducens
an aneurysm of posterior communicating artery, posterior cerebral artery, and superior cerebellar artery
what is the function of V3 (mandibular branch) of CN 5
GSA and SVE (sensory and motor)
- sensation from skin of mandible, lower lip, side of head, mandibular teeth, anterior 2/3 of tongue
- motor to muscle of mastication (temporalis M. and massesster M. )
- **not taste this is pain sensation of hot and cold
what is the tract of trochlear n.
exits DORSALLY (only one) off midbrain and pierces dura mater at the margin of the tentorium cerebella and runs in the lateral wall of the cavernous sinus to enter the orbit via the superior orbital fissure
dental trauma affects what CN?
trigeminal
mainly the maxillary and mandibular branches
a pituitary tumor and can what
compression of the optic chiasm and cause loss of vision laterally in both visual fields (bitemporal hemianopia )
what clinical test asses the optic nerve
light and dark test (after trauma) finger counting (after trauma) snelles test visual field test (all 4 quandrants) peripheral vision pupillary light reflex blink reflex
how to test for CN 9 and 10
glossopharyngeal and vagus
- parotid reflex -9
- taste - 9
- gag reflex 9, 10
- swallowing reflex - 10
- speech -10
- deviation of uvula - 10
what does the pupillary reflex test
optic and oculomotor nerves (CN 2 and 3)
- afferent (sensory) to see: optic
- efferent (motor) to constrict pupil : oculomotor
what is glossopharyngeal neuralgia
irritation to CN 9 causing pain when eating
what is the function of trigenminal nerve (nerve 5)
SVE: motor innervation to mastication (arch 1)
GSA: sensory info to the face and scalp
tract of CN 12
from medulla and exits via hypoglossal canal and travels in cervical plexus, crosses occipital A., and enters oral cavity
what is the function of facial nerve (CN 7)
SVE: (special organ motor) innervation of muscles of facial expression (arch 2)
GVE: (autonomics -PNS, viscera motor)- PNS innervation to lacrimal, nasal, palatine submandibular, and sublingual glands
SVA: (special organ sensory) - taste to anterior 2/3 tongue
GSA: ( skin sensation) - sensation external acoustic meatus
