LECTURE 7: cranial nerves; Flashcards
How many CN are in the midbrain
2 CN , III and IV
how many CN are in the pons
4 CN , V-VIII
how many CN are in the medulla
4 CN, IX - XII
how many pairs of CN exit from the surface of the brain stem
12
what does CN X innervate
throacic/ abdominal viscera
which neurons are axons and receptors of CNs are part of the PNS , myelinated by Schwann cells
sensory
which CNs are entirely within the skull and technically have no peripheral component, myelinated by oligodendroglia, making them susceptible to certain diseases
(MS)
CN I and II
where are the nuclei of the motor neurons
inside the brain stem
what foramen does CN I exit form
cribiform plate
what foramen does CN II exit form
optic canal
what foramen does CN III exit form
superior orbital fissure
what foramen does CN IV exit form
superior orbital fissure
what foramen does CN V exit form
V1- superior orbital fissure
V2- foramen rotundum
V3- foramen ovale
what foramen does CN VI exit form
superior orbital fissure
what foramen does CN VII exit form
auditory canal ( stylomastoid foramen)
what foramen does CN VIII exit form
auditory canal
what foramen does CN IX exit form
jugular foramen
what foramen does CN X exit form
jugular foramen
what foramen does CN XI enter and exit from
enters skull via foramen magnum and exits via jugular foramen
what foramen does CN XII exit form
hypoglossal foramen
what is the motor innervation for the CN
muscles of face, eyes, tongue, jaw, and 2
neck muscles
the CNs get somatosensory information from
skin and muscles of face and
temporomandibular joint
what is the only sensory input that reaches cortex without going thru thalamus
CN1
what is Anosmia and which CN can this be a disease from
loss of sense of smell and CN 1
where does the reflex of CN 2 happen
midbrain
if there is a loss of function of optic nerve between chiasm and eyes what will it cause
ipsilateral blindness
what is damage in R visual cortex or along path prior to optic chiasm called
L homonymous hemianopsia
dilation is part of what nervous system
sympathetic
constriction is part of what nervous system
parasympathetic
what are the clinical implications of the oculomotor nerve
external strabismus
ipsilateral ptosis
diplopia
mydriasis
what is External strabismus
ipsilateral eye fixed
in abd
what is Ipsilateral ptosis
paralysis of upper
eyelid
what is Diplopia
double vison
what is mydriasis
Ipsilateral pupil fully dilated
which muscle of the eye is involved with rotation
inferior oblique
what muclse of the eye lifts your eyelid
levator palpebrae superioris
what does the trochlear n inn
superior oblique muscle
what does the superior oblique muscle do
rotates the eye
what is the only CN that exits from the dorsum of the brainstem
CN IV
what are the clinical implications of CN IV, trochlear n
ilpilaterla eye can not look down and in
what does the motor branch of the mandibular n innervates
muscle of mastication
massester
temporalis
medial/lateral pterygoid
what is CN V triggered by
tactile stimulation of cornea
what is the consensual blink response?
1st order neuron – trigeminal ganglion
2nd order neuron – spinal trigeminal nucleus
to interneuron in reticular formation
To B CN VII facial n to B orbicularis oculi to
blink both eyes
if a patient has numbness of same side of face and inside of mouth which CN can be impaired
CN V
if the jaw deviates toward the weak side due to unbalanced action of internal pterygoid of strong side which CN can be impaired
CN V
what is sharp shooting facial neuropathic pain set off by stimulation not normally painful
trigeminal neuralgia
is there sensory loss with trigeminal neuralgia
no
what innervated the lateral rectus m
CN VI : abducens
which CNs can cause double vision
IV, III , VI
the facial n inn the parasympathetic fibers of
superior salivatory n
all salivary glands except parotid
the facial n signals to and from CN VII and have nuclei where
pond , medulla and upper sc
if a patient has a R upper motor neuron lesion in the brain (cortical stroke) what pattern of facial weakness would u see compared to a lower motor neuron lesion
upper motor neuron lesion would effect only half of the left side of the face because the supper face is bilateral
if there was a lower motor neuron lesion then the whole left side wold be weak because it is effecting the whole lower face and upper fave
cortical control of the upper face is
bilateral
cortical control of the lower face is
contralateral
what Tends to come from viral or immune
disorder that causes swelling of facial n
within temporal bone that can cause
compression/ischemia
bell’s palsy
what does teh vestibular branch tramsmit in CN VIII
info related to head position and mvmt
what does the cochlear branch transmit in CN VIII
info related to hearing
where are the peripheral receptors in vestibular
apparatus and cochlear organ
inner ear
what is included in the vestibular apparatus:
▪ Utricle
▪ Saccule
▪ 3 semicircular canals (SCC)
membranous labyrinth is suspended within what
body labyrinth
what separated bony/membranous labyrinths
periphymph
what is inside membranous labyrinth
endolymph
what receptors are inside membranous labyrinth
hair cell
head mvmt causes movement of ___ inside to move embedded hair cells to fire ________
endolympth to fire vestibular branch of CN VIII
what happens inside the semicircular canals
responds to rotational acceleration/ deceleration of head
what happens inside of utricle and saccule
responds to head position relative to
gravity and linear acceleration/deceleration
what connections account for activating effect of sound on CNS
reticular formation
what is directly and via superior olive, info is integrated from B ears to locate sounds
inferior colliculus
what serves as thalamic relay station to primary auditory cortex
medial geniculate body
what 3 cortical areas process auditory information:
auditory cortex
auditory association cortex
wernicke’s area
what does teh auditory cortex do
conscious awareness of sounds
what compares sounds with memories of other sounds and categorizes them
auditory association cortex
what is Wernicke’s area
comprehension of spoken language
what does loss of hearing in one ear interfere with
the ability to locate sounds
what is deafness as a result of peripheral disorders is classified as
conductive or sensorineural
when does conductive deafness occur
when transmission of vibrations is prevented in the
outer or middle ear
what are common causes of conductive deafness
excessive wax in the outer ear canal or otitis media
what deafness is due to damage of receptor cells or the cochlear nerve
sensorineural
what are common causes for sensorineural deafness
acoustic trauma, ototoxic drugs, Ménière’s
disease, and acoustic neuroma.
the vestibular branch of CN VIII ransmits information from hair cells of SCCs, utricle, and saccule to:
▪ Vestibular nuclei in medulla and pons
▪ Flocculonodular lobe in cerebellum
what are the clinical implications of vestibular branch CN VIII
causes vertigo and dizziness
where do the motor fibers of the glossopharangeal n inn
stylopharyngeus m
where do the parasympathetic fibers of the glossophartangeal n go to
parotid salivary gland and carotid body/sinus (O2 and BP
where do the somatosensory fibers in the glossopharangeal n go to
soft palate, pharynx, around ear, and post 1/3 of tongue
where is the info from the glossopharangeal nerev get processed at
in nucleus in medulla and upper cervical SC
the somatic motor of the vagus nerve goes where
to the tongue
the parasympathetic motor fibers of the vagus nerve do what
decrease HR, constrict
bronchi, and increase digestion
what nerve is the efferent part of the gag and swallowing reflex
vagus
what is the only nerve that enters and exits the skull
CN XI : accessory
what muscles do the CN XI innervate
SCM and tramps
where are the cell bodies of the CN XI located
in spinal accessory nucleus
what are the clinical implications for CN XI
▪ Weakness when turning head to side opposite
lesion
▪ Downward rotation of scapula
what CN Innervates all intrinsic tongue mm and ¾ extrinsic
tongue mm
CN XII
where are the cell bodies of the hypoglossal n found
in hypoglossal nucleus of medulla
what lesion causes flaccid paralysis/atrophy of ipsilateral
tongue mm, so tongue deviates towards side of
lesion when protruded
LMN lesion of CN XII
what lesion causes inactivity of contralateral tongue mm so
tongue deviates to side opposite of lesion
UMN lesion of CN XII
what is it called if you have difficulty swallowing
dysphagia
what is dysarthria
poor control of speech muscles
