LEC54: Cranial Nerves II

Question 1

function of SVE, special visceral efferent, fibers?

Answer 1

fibers innervating muscles derived from a branchial arch

Question 2

function of SVA, special visceral afferent, fibers?

Answer 2

fibers that deal w/ GUT-RELATED SENSE of head/neck:

1) taste
2) smell

Question 3

function of SSA, special somatic afferent, fibers?

Answer 3

NON-GUT related to special SENSE fibers of head/neck:

1) vision
2) balance
3) hearing

Question 4

what kinds of nerve fibers present in head/neck?

Answer 4

both special and general just b/c in head/neck, doesn’t mean it’s ONLY special fibers- also have general

Question 5

which CN are special sensory nerves?

Answer 5

1) CNI: olfactory
2) CNII: optic
3) CNVII: vestibulocochlear

Question 6

what is unique about CNI, CNII?

Answer 6

CNI, olfactory & CNII, optic ARE NOT REALLY NERVES;

nerve must come from a nucleus, go to effector organ, or have sensory ganglia somewhere;

these are actually BRAIN TRACTS

Question 7

fiber type in CNI, olfactory n? fxn?

Answer 7

SVA ONLY

helps w/ flavor detection by bringing in air

Question 8

fiber type of CNII, optic n? fxn?

Answer 8

SSA ONLY

nerve of vision

transmits info from retina > brain

Question 9

function and significance of central artery of the retina?

Answer 9

an END ARTERY w/ NO collaterals

when lose this, lose vision

Question 10

fiber type of CNVII, vestibulocochlear n? fxn?

Answer 10

SSA only

balance!

vestibular and auditory systems

Question 11

which CN are myotomal?

Answer 11

1) CNIII, oculomotor
2) CNIV, trochlear
3) CNVI, abducens
4) CNXII, hypoglossal

Question 12

derivation of myotomal CNs?

Answer 12

somites

Question 13

what fiber type for all myotomal CN?

Answer 13

GSE

Question 14

fiber types/fxn of CNIII, occulomotor?

Answer 14

GSE & GVE-autonomics

Question 15

what do autonomics of CNIII do?

Answer 15

preganglionic parasympathetics, do pupillary constriction

Question 16

location of CNVI, abducens? susceptibility therein?

Answer 16

lies on clivus bone

v susceptible to pontine tumors

Question 17

which CN is big motor nerve of tongue?

Answer 17

CNXII, hypoglossal

Question 18

which CN are branchioneric?

Answer 18

1) CNV: trigeminal
2) CNVII: facial
3) CNIX: glossopharyngeal
4) CNX: vagus
5) CNXI: spinal accessory n
* branchioneric = derived from branchial arches, so have to do w/ neural crest cells*

Question 19

muscle type related to branchioneric nerves?

Answer 19

skeletal

Question 20

what is most widespread nerve in the head?

Answer 20

CNV, trigeminal

Question 21

fiber types for CNV, trigeminal

Answer 21

SVE, GSA

(mainly GSA)

Question 22

divisions of trigeminal n?

Answer 22

1) opthalmic
2) maxillary
3) mandibular

Question 23

what controls ability to stick out tongue?

Answer 23

CNV, trigeminal’s GSA fibers

Question 24

what does CNV, trigeminal, innervate?

Answer 24

1) muscles of mastication
2) muscles of tongue
3) corneal reflex
4) facial sensory innervation
5) mucosa of inernal paranasal sinuses

Question 25

which divisions of CNV, trigeminal n innervate which parts of face?

Answer 25

Question 26

what is trigeminal neuralgia?

Answer 26

aka *tic douboureaux* usu limited to 1 division of trigeminal on 1 side extremely painful

Question 27

fiber types for CNVII, facial n

Answer 27

1) SVE 2) GSA - swatch near auricle 3) SVA - taste! 4) GVE

Question 28

what is chorda tympani?

Answer 28

nerve that originates in taste buds in front of tongue; runs through middle ear; carries taste messages to brain joins CNVII (facial n) inside facial canal therefore facial n, CNVII, carries taste

Question 29

fiber types of CN IX, glossopharyngeal n?

Answer 29

1) SVE 2) GSA 3) SVA 4) GVE 5) **GVA - **coming back from pharynx endodermal *\*5 fiber types here - greater # found in any CN!\**

Question 30

fiber types of CN X, vagus n

Answer 30

1) SVE 2) GSA 3) SVA 4) GVE 5) GVA * \*5 fiber types, like CN IX!\* *

Question 31

what is cricothyroid m? what supplies it?

Answer 31

muscle of larynx CNX, vagus n supplies it

Question 32

fiber types for CN XI, spinal accessory n? structure of CN XI?

Answer 32

SVE 1) cranial root 2) spinal root

Question 33

distribution of cranial root of CN XI, spinal accessory n? fiber type?

Answer 33

1) goes into CNX, vagus 2) distributed in recurrent laryngeal n SVE fibers

Question 34

distribution of spinal root of CN XI, spinal accessory n? fiber type? what does it innervate?

Answer 34

1) goes into vagus, CN X 2) comes out as own nerve, spinal accessory n SVE fibers innervates trapezius, sternocleidomastoid mm

Question 35

what do CN IX and CN X share? what is their relationship?

Answer 35

4 brain stem nuclei are very tight nerves

Question 36

is there a correlation btwn nerve deafness and nerve balance features? why/why not?

Answer 36

no b/c vestibular and cochlear nerves come from diff pts on brain stem

Question 37

major motor innervator of tongue?

Answer 37

CN XII, hypoglossal n

Question 38

where does thyroid come from?

Answer 38

foramen cecum

Question 39

what is secondary motor innervator of the tongue?

Answer 39

palatoglossas n, from CNX, XI

Question 40

what is anterior 2/3 of tongue covered in?

Answer 40

ectoderm

Question 41

what embryonic tissue type is posterior 1/3 of tongue derived from?

Answer 41

endoderm

Question 42

what provides general sensation to anterior 2/3 of tongue?

Answer 42

GSA from CN V

Question 43

what provides taste for anterior 2/3 of tongue?

Answer 43

SVA from CN VII chorda tympany

Question 44

what fiber type & from which nerve provides sensory innervation to posterior 1/3 of tongue?

Answer 44

GVA by CN IX GVA not GSA since endodermally derived

Question 45

what fiber type & from which nerve carry taste for posterior 1/3 of tongue?

Answer 45

SVA, CN IX, glossopharyngeal

Question 46

which CN carries taste sensation for epiglottis?

Answer 46

CN X

Question 47

what is main sensory nerve for gag reflex?

Answer 47

CN IX, glossopharyngeal n