LEC50: Cranial Nerves I Flashcards by Allison Vise

2 types of bone formation of human skull

1) bottom: cartilagenous endochondral
2) face: membranous

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which area of the skull is evolutionarily older?

bottom of skull, the chondrocranial base

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which area of skull is malleable? which is not? why?

face/vault is malleable

bottom of skull isn’t malleable b/c cranial foramina there, where nerves exit / vascular supply enters

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what is fontanella?

soft spot on top of baby’s skull

newborn’s face/vault very malleable; skull base is not malleable

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what is hydrocephalus

abnormal accumulation of CSF in brain; increases intracranial pressure inside skull, progressively enlarges head

most common in infants

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what view of skull is this

exocranial view of skull

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what view of what structure is this? what does it enable visualization of?

endocranial view of skull base

see important foramina

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list cranial nerves, by number and name

I: olfactory

II: optic

III: oculomotor

IV: trochlear

V: trieminal

VI: abducens

VII: facial

VIII: vestibulo-cochlear

IX: glossopharyngeal

X: vagus

XI: spinal accessory

XII: hypoglossal

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“general” nerve fibers defn, types

fibers that can be found anywhere in the body

4 types:

GSE, general somatic efferent

GVE, general visceral efferent

GSA, general somatic afferent

GVA, general visceral afferent

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meaning of “general” re: spinal nerves

found anywhere in the body

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meaning of “somatic/visceral” re: spinal nerves

visceral: gut innervated
somatic: not gut innervated

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meaning of “efferent/afferent” re: spinal nerves

efferent: motor
afferent: sensory

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“special” nerve fibers of the head/neck (3)

1) SVE, special visceral efferent
2) SVA, special visceral afferent
3) SSA, special somatic afferent

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what are SVE fibers? why visceral?

MOTOR fibers relating to muscles derived from the branchial arches

VISCERAL designation THOUGH GO TO SKELETAL MUSCLE! because branchial arches at first were part of aero-digestive system

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what are SVA fibers?

fibers relating to taste, smell

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what are SSA fibers?

non-gut related special sense fibers

vision, balance, hearing

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how many types of fibers can a cranial nerve have?

up to 7 because 4 general and 3 special types of fibers

however, max number found is 5!

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3 groupings of cranial nerves

1) special sensory nerves
2) myotomal nerves
3) branchiomeric nerves

*3, 4, 5 system of subdividing cranial nerves*

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special sensory nerves are?

*3*

I: olfactory

II: optic

VIII: vestibulo-cochlear

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myotomal nerves are? general fxn?

III: oculomotor

IV: trochlear

VI: abducens

XII: hypoglossal

innervate skeletal muscle derived from myotomes

*4*

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branchiomeric nerves are? general fxn?

V: trigeminal

VII: facial

IX: glossopharyngeal

X: vagus

XI: spinal accessory

nerves related to branchial arches

*5*

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fiber type, CNI: olfactory nerve

SVA

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fiber type, CNII: optic nerve

SSA

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fiber type, CNVIII: vestibulo-cochlear n

SSA

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what is misnomer about CNI: olfactory n / why?

not actually a nerve; it's a brain tract was called nerve historically, so misnomer stuck nerve must either: 1) if motor, go from motor nucleus \> muscle or 2) if sensory, have a primary sensory neuron in a ganglia - CNI has neither

structure of CNI: olfactory n?

olfactory tract, bulb, nerve

important structures of this image?

olfactory bulb, nerve, tract specialized sensory epithelium communicates w/ mitral tufted cell and nerve

hyperosmia

heightened sense of smell re: CNI, olfactory nerve cocaine users have hyperosmia

cacosmia

condition where always perceive foul odors, even if none present

what's unique about CNII: optic nerve structure?

is an optic tract/brain tract, like olfactory nerve- it's NOT A NERVE

where does CNII: optic nerve run?

from visual cortex \> through optic foramena

where is CNI: olfactory n located?

small fibers in nose septum and undearneath in turbiantes lying on superior nasal concha pass through cribiform plate of ethmoid bone

what foramena is this? what goes through it?

optic foramena CNII, optic n

how does 1-eyed blindness present in brain?

atrophy of optic n

is brain sensitive to pain?

no, dura surrounding brain is

astrocytoma?

tumor in brain - swelling in brain tissue

where do you find optic astrocytoma?

near chiasm

function of CNVIII

CNVIII: vestibulocochlear nerve hearing, balance

where does CNVIII: vestibulo-cochlear nerve exit skull base

internal acoustic meatus

fiber type of nerves i nmyotomal nerve group?

all are GSE EXCEPT CNIII, oculomoter, also GVE parasympathetic fibers

nerves of oculomotor system, function

CNIII, oculomotor; IV, trochlear; VI, abducens move the eyeball

which cranial nerves are innervating this structure

III, IV, VI

what is this condition? what cranial nerve's affected?

congenital bilateral external rectus palsy CNVI: abducens palsy

what is major nerve for tongue innervation?

hypoglossal n

what nerve fiber type do all branchiomeric group nerves have?

SVE, because derived from branchial arches

nerve fiber types for CNV, trigeminal n

SVE, GSA

nerve fiber types for CNVII, facial n

SVE: branchial mm - 2nd arch GSA: general somatic sensation GVE: parasympathetic fibers SVA: taste, anterior 2/3 tongue

nerve fiber types for CNIX, glossopharyngeal n

SVE: branchial mm, 3rd arch GVA: general visceral sensation GVE: parasympathetic fibers GSA: general somatic sensation SVA: taste, posterior 1/3 of tongue

nerve fiber types for CNX, vagus

SVE: branchial mm, 4th arch GSA: general somatic sensation GVE: parasympathetic fibers GSA: general somatic sensation SVA: taste, epiglottis

nerve fiber types, CNXI, spinal accessory n

SVE: branchial archs 5-6 GSE: spinal part

what innervates mastication muscles?

SVE of CNV, trigeminal n

CNV, trigeminal n, divisions?

V1: opthalmic V2: maxillary V3: mandibular

name nerve, divisions

trigeminal n green: V1, opthalmic blue: V2, maxillary salmon: V3, mandibular

sensory field of CNV, trigeminal n, both re: divisions and overall

cause and presentation of trigeminal neuralgia? possible cause?

compression of 1 division of trigeminal n unrelenting, intense pain possible cause- artery compressing nerve/branches

functions of CNVII, facial n?

facial expression muscles- smile, frown, close eyelids carries taste from anterior 2/3 of tongue

where does CNVII, facial n, pass through?

through temporal bone's internal auditory canal through parotid gland \> facial muscles

what is this example of?

bell's palsy aka facial palsy CNVII, facial n, insulted

nerve fibers of glossopharyngeal n, CNIX?

5! most found in any CN (+ vagus also 5) SVA: branchial, 3rd arch GVA GVE: parasympathetic GSA SVA: taste, posterior 1/3 tongue

key nerve for gag reflex?

CNIX, glossopharyngeal nerve

what comes out of jugular foramen?

CNIX- glossopharyngeal, CNX- vagus

what structure carries taste?

epiglottis

nerve fibers/their fxns for CNX, vagus?

SVE- branchial, 4th arch GVA GVE GSA SVA- taste, epiglottis

where are primary sensory neurons of cranial nerves located?

in ganglia OUTSIDE the CNS - like DRGs of spinal nerves

which cranial nerves do not have ganglia?

CNI, CNII because not real nerves

sensory ganglia of the cranial nerves?

CNV: trigeminal (semilunar) ganglion - LARGEST, MOST IMPORTANT CNVII: geniculate ganglion CNVIII: vestibular ganglion; cochlearn (spiral) ganglion CNIX: superior and inferior glosspoharyngeal ganglia CNX: superior (jugular) and ifnerior (nodose) ganglia

what is a shockingly sensitive part of the body?

auricle

what provides auricular sensation and to where?

CNV- auriculotemporal branch CNVII- small area, posterior canal wall CNIX- medial, inner part of tympanic membrane (tympanic n) CNX- most of ear canal, pt of outer surface of tympanic membrane (auricular br; arnold's s n) Greater auricular n (C2, C3) Lesser occipital n (C2)

nerve fiber types of parts of CNXI, spinal accessory n

SVE- cranial root GSE- spinal part

what does spinal part of CNXI innervate?

trapezius m- adduct arm, elevate shoulder sternocleidomastoid m- tilts, rotates head

what happens to cranial part of CNXI, spinal accessory n?

joins CNX, vagus n

what is spinal accessory nerve's route?

UNIQUE b/c both enters and exits skull: arises from C1-C5 ventral horn cells; forms trunk ascends into skull thru foramen magnum then exits skull thru jugular foramen, with CNX runs backwards, descends obliquely behidn digastric and stylohyoid muscles to upper pt of sternocleidomastoid; courses obliquely across neck, to trapezius m

LEC50: Cranial Nerves I Flashcards

(72 cards)