Exam 2: Unit IV: CN VIII, XI, XII Flashcards

1
Q

What type of fibers does the vestibulocochlear nerve carry?

A

sensory only

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2
Q

What makes the Vestibulocochlear nerve unique?

A

it is composed of two nerves:

  1. Vestibular nerve
  2. cochlear nerve
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3
Q

Where does the Vestibular Nerve (of CN VIII) terminate?

A

in the vestibular nuclear complex (consists of 4 parts)

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4
Q

What are the four parts the vestibular nuclear complex consists of?

A
  1. Superior
  2. Medial (receives most fibers)
  3. Lateral (sends to vestibulospinal tract)
  4. Inferior
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5
Q

Where do the cell bodies of the fibers carried in the Vestibular nerve arise from? Where is the location of this structure?

A

vestibular ganglion; which has an inferior and superior part; located in internal acoustic meatus

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6
Q

Where does the cochlear nerve terminate?

A

in two cochlear nuclei; anterior and posterior

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7
Q

Where do the axons of the cochlear nerve arise from? Where is the location?

A

from the spiral ganglion located in the cochlea

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8
Q

The cochlear nerve is made up of _____ neurons whose cell bodies are in the ______ ganglion of the cochlea.

A

bipolar; spiral

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9
Q

Where do the peripheral processes (dendrites) of the cell bodies in the spiral ganglion extending to? (ass. with cochlear nerve)

A

spiral organ (organ of Corti)

(recall: these dendrites are bringing info in from the spiral organ TO the spiral ganglion

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10
Q

Where do the axons of the cell bodies located in the spiral ganglion go to? Where is this located?

A

carried in the cochlear nerve and terminate on two cochlear nuclei –> located in the posterior, superior medulla oblongata, lateral to the vestibular nuclei

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11
Q

Describe the path of the axons from the cochlear nuclei to where they synapse.

A

axons cross to other side of brainstem and synpase in trapezoid nuclei or the superior olivary nucleus

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12
Q

What do the axons form that are ascending from the trapezoid nucleus or the superior olivary nucleus form?

A

lateral lemniscus

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13
Q

Where are the peripheral processes from the vestibular ganglion extending to? (technically bringing info in from)

A

Three inner ear structures:

  1. saccule
  2. utricle
  3. semicircular canals
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14
Q

Where are the central processes of cell bodies located in the vestibular ganglion going to? Where is this located?

A

to vestibular nuclei, located in MO on floor of rhomboid fossa

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15
Q

Where do MOST vestibular nerve fibers terminate? Then where do they go?

A

in medial vestibular nucleus (MGB) –> then to cerebellum (specifically vestibulocerebellum)

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16
Q

Where do SOME vestibular nerve fibers travel directly to? Via what?

A

directly to cerebellum via inferior cerebellar peduncle

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17
Q

T/F. Equilibrium info from the vestibular nerve will eventually end in the cerebral cortex.

A

False– goes to cerebellum only –> and info from here will mainly go to lateral vestibular nucleus

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18
Q

What are the other names for the vestibular nuclei:

  1. superior
  2. medial
  3. lateral
  4. inferior
A
  1. Bechterew
  2. Schwalbe
  3. Deiter
  4. (none)
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19
Q

T/F. All branches of CN VIII originate inside the ear and terminate in the CNS, in other words, it has NO branches to structures outside the ear.

A

True

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20
Q

What is the apparent origin of the vestibulocochlear nerve?

A

in the cerebellopontine angle/recess

recall: CN VII is right here too

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21
Q

How does CN VIII travel from its apparent origin in the cerebellopontine recess?

A

travels in the posterior cranial fossa to the internal acoustic meatus

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22
Q

What other nerve enters the internal acoustic meatus with CN VIII?

A

the facial nerve

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23
Q

How many fibers does the cochlear nerve carry?

How many fibers does the vestibular nerve carry?

A

30-40,000 fibers

20,000 fibers

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24
Q

T/F. The vestibular nerve carries more fibers than the cochlear nerve.

A

False. Cochlear nerve carries more fibers than the vestibular nerve

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25
Q

Describe the path of the cochlear nerve once it enters the internal acoustic meatues.

A

Transverses the internal acoustic meatus inferior to the facial nerve—> after it leaves the temporal bone it reaches the spiral ganglion of the cochlea

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26
Q

What does the vestibular nerve do as it approaches the ear?

A

divides into superior and inferior branches

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27
Q

From the vestibular nerve, which branch is smaller, the superior or inferior branch? How many fibers in each?

A
inferior branch (~ 8,000 fibers)
superior branch (~12,000 fibers)
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28
Q

What branches for the smaller inferior nerve of the vestibular nerve? What do they supply?

A
  1. saccular nerve –> saccule

2. posterior ampullary nerve –> posterior ampullary crest

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29
Q

What nerves form the larger superior branch of the vestibular nerve? What do they supply?

A
  1. lateral ampullary nerve –> lateral semicircular canal
  2. anterior ampullary nerve–> anterior semicircular canal
  3. Voit’s nerve –> saccule
  4. branch directly off superior branch and branch off lateral ampullary nerve –> utricle
30
Q

What two nerves supply the utricle?

A

(via vestibular nerve)

  • branch from lateral ampullary nerve
  • branch directly off superior branch
31
Q

What are the two nerves that supply the saccule?

A
  • saccular nerve (branch off inferior nerve of vestibular nerve)
  • Voit’s nerve (branch of superior nerve)
32
Q

What are two tumor associated with CN VIII?

A
  1. acoustic neuroma–> loss of hearing

2. Vestibular Schwanoma —> equillibrium/balance problems

33
Q

What is the term for ringing in the ears?

A

tinnitus

34
Q

What disease can tinnitus be the the first sign for?

A

Meniere’s Disease (syndrome)

35
Q

What are three characteristics associated with Meniere’s Disease?

A
  • vertigo
  • tinnitus
  • hearing loss
36
Q

What can people with sensorineural hearing loss (ass. with actual CN VIII) get?

A

Cochlear implants

no issues with cochlea itself/three bones in ear

37
Q

What is cervicogenic vertigo?

A

dizziness from mechanoreceptors in cervical zygapophyseal joints being stimulated

38
Q

How does one distinguish Vestibular Disease from Cervicogenic Vertigo?

A

need to stimulate cervical mechanoreceptors w/o stimulating equilibrium

  • place patient in swivel chair and hold head in palce and turn them
    • if vertigo not produced –> thinking might be Vestibular Disease
    • if it does produce vertigo –> it is Cervicogenic Vertigo
39
Q

What type of fibers does the Accessory Nerve carry?

A

motor only

40
Q

There are two roots that contribute to the Accessory Nerve, what are they?

A

Cranial root and Spinal root

41
Q

What muscles does the Cranial and Spinal root of the Accessory root supply?

A
  • SCM
  • Trapezius
  • muscles of soft palate
  • pharynx
  • larynx
42
Q

What are the two nuclei of origin for the Accessory nerve?

A
Nucleus ambiguus (for cranial root)
Spinal Nucleus of the Accessory Nerve (for spinal root)
43
Q

Where are the cell bodies located that contribute to the cranial root of the accessory nerve?

A

nucleus ambiguus (also goes to CN IX, X)

44
Q

Where is the location of the nucleus of origin for the spinal root of CN XI located?

A

Spinal nucleus of the accessory nerve is found in anterior horn of the gray matter; ~ foramen magnum to C5, C6 cord level

45
Q

Where does the cranial root emerge from? What does it combine with? And where does it exit the skull through?

A

medulla oblongata, combines briefly with the spinal root and exits the skull via jugular foramen

46
Q

When do the fibers of the cranial root do after they exit the jugular foramen?

A

they separate from the spinal root and join the vagus nerve at the inferior ganglion

47
Q

Once the fibers of the cranial root get to the inferior ganglion, what are they carried in?

A

carried in the vagus

48
Q

What do fibers of the cranial root of the accessory nerve distribute to?

A
  • pharyngeal plexus
  • external laryngeal nerve
  • recurrent laryngeal nerve
49
Q

What do the fibers of the cranial root of the accessory nerve contribute motor supply to?

A

laryngeal muscles, EXCEPT circoarytenoid

50
Q

Where do the rootlets contributing to the spinal root of the accessory nerve emerge from?

A

the lateral aspect of the cervical cord, b/w the anterior and posterior rootlets

51
Q

What do the rootlets of the spinal root of the accessory nerve combine to form? How do they ascend?

A

combine to form a trunk; ascend b/w the denticulate ligaments and the posterior rootlets

52
Q

How does the spinal root of the accessory nerve ENTER the skull?

A

via foramen magnum

53
Q

Once the spinal root of the accessory nerve is in the skull, where does it go? How does it exit the skull

A

passes laterally and combines with the cranial root and exits the skull via the jugular foramen

54
Q

What does the spinal root of the accessory nerve pass deep to and send motor fibers to?

A

sternocleidomastoid

recall–this is mark b/w ant. and post. triangles

55
Q

After the spinal root passes deep to the SCM, where does it go?

A

traverses the posterior triangle and travels deep to the trapezius muscle and supplies it

56
Q

What two muscles does the spinal root of the accessory nerve supply?

A

SCM

Trapezius

57
Q

Some sources state the trapezius receives some motor supply from other places besides the accessory nerve, what are those other places? What “parts” of the trapezius are they said to supply?

A

cervical plexus

accessory nerve –> upper and middle
cervical plexus–> lower 2/3

58
Q

If the SCM is paralyses, what root is having an issue, and which way can the face not turn?

A

spinal root; cannot turn face to opposite side

59
Q

What is spasmodic torticollis?

A

unilateral episodic contraction of SCM and maybe trapezius

60
Q

If the trapezius is effected due to issues with the spinal root of the accessory nerve, what can occur?

A

scapula descends and get excessive traction of the brachial plexus

61
Q

What type of fibers does the Hypoglossal nerve carry? What does it supply?

A

motor only

- intrinsic and extrinsic muscles of the tongue, EXCEPT the palatoglossus

62
Q

What is the nucleus of origin for CN XII? Where is it located?

A

nucleus of the hypoglossal nerve; located on the floor of the rhomboid fossa

63
Q

Where is the apparent origin of the Hypoglossal nerve/ where does it emerge?

A

emerges as a series of rootlets in sulcus b/w the pyramid and the olive of the MO

64
Q

What do the rootlets of the Hypoglossal nerve combine to form?

A

two bundles

65
Q

How do the bundles of the Hypoglossal nerve exit the skull?

A

via the hypoglossal canal as separate entities and combine upon exiting the canal

66
Q

After the Hypoglossal nerve exits the skull via the hypoglossal canal, what is its course?

A

descends, forming a loop call the arch of the hypoglossal nerve, and reaches the base of the tongue

67
Q

After the hypoglossal nerve reaches the base of the tongue, what occurs?

A

fibers distribute into terminal branches supplying the muscles of the tongue

68
Q

Describe the communication of some cervical nerves with the hypoglossal nerve.

A

some fibers from C1 and C2 cervical nerves travel with, but DO NOT become incorporated into the hypoglossal nerve
- some separate, some continue with the hypoglossal nerve

69
Q

When the fibers from C1 and C2 separate from the hypoglossal nerve, what do they form?

A

the superior root of the ansa cervicalis

70
Q

What to the cervical fibers that continue with the hypoglossal nerve ultimately supply?

A

the geniohyoid and thyrohyoid muscles

71
Q

What do the lingual branches of the hypoglossal nerve supply?

A
  • hyoglossus
  • genioglossus
  • styoglossus
72
Q

If there is injury to a hypoglossal nerve how will it manifest?

A
  • unilateral issues
  • 1/2 of tongue will atrophy (hemiatrophy)
  • stick tongue out and will deviate toward side of damage
  • larynx deviate to “normal” side when swallowing