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704 > Cranial Nerves_ Pons > Flashcards

Cranial Nerves_ Pons Flashcards

1
Q

What are the 2 parts of the pons?

A
  1. tegmentum

2. basis points

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2
Q

Tegmentum =

A
  • dorsal portion containing cranial nuclei and ascending and descending tracts.
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3
Q

Where does the tegmentum lie?

A

This region lies just below the fourth ventricle.

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4
Q

Basis points =

A

ventral portion containing pontine nuclei and crossing pontine fibers running transversely which will make up middle cerebellar peduncle.

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5
Q

This ventral portion is marked by large fascicles of fibers containing _________________________________________ axons. These axons are running in the _______________ direction.

A

corticospinal, corticobulbar and corticopontine

caudal

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6
Q

What are the 3 cerebellar peduncles:

A

inferior, middle and superior

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7
Q

Where are the 3 cerebellar peduncles located?

A

@ the pontine level

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8
Q

As a general principle, these allow for cerebellar afferents to enter (___________________) and exit (________________) the cerebellum.

A

inferior and middle

superior

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9
Q

What are the 4 cranial nerves associated with the pons:

A

CN VIII, VII, VI, V

vestibulocochlear, facial, abducens and trigeminal

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10
Q

Cochlear Division =

A

relay of auditory information from specialized receptor, the cochlea

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11
Q

Auditory information is distributed _________________ through brain stem and cortical auditory areas.

A

bilaterally

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12
Q

Therefore, unilateral lesions of CNS auditory structures do:

A

not result in unilateral deafness

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13
Q

Damage to the CN VIII or both cochlear nuclei will result in:

A

ipsilateral deafness

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14
Q

The entire system is ________________ organized (remember that other sensory systems are topographically organized).

A

tonotopically

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15
Q

(Ultimate goal is cerebral cortex.) Specifically, the superior surface of the _____________________ gyrus (within the lateral sulcus). Brodmann’s areas 41 and 42; primary auditory cortex; Transverse Temporal Gyri of ______________.

A

superior temporal

Heschl

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16
Q

Much cross-communication takes place between sides before arriving at cortex. The bilateral representation is complex and actual relay steps are unclear. It does however support the ability to:

A

localize sound to one side.

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17
Q

Cochlear Nerve:

  1. Consists of axons or central processes of neurons bringing afferent information from the ________________.
  2. Enters brainstem at _______________________, then bifurcates to synapse in both dorsal and ventral cochlear nuclei.
  3. Nuclei are superficial and located in rostral (open) medulla, adjacent to the base of the _______________________.
A

inner ear

cerebellopontine angle

inferior cerebellar peduncle

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18
Q

Name the 7 landmarks of the ascending system:

A
  1. Dorsal and ventral cochlear nuclei.
  2. Superior olivary nucleus.
  3. Lateral lemniscus.
  4. Nucleus of inferior colliculus.
  5. Brachium of inferior colliculus.
  6. Medial geniculate nucleus.
  7. Primary auditory cortex.
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19
Q

Protective auditory reflexes: Inferior colliculus >

A

superior colliculus

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20
Q

superior colliculus >

A

tectospinal tract

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21
Q

tectospinal tract =

A

reflex turning of head to sound

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22
Q

IMPORTANT for protection against loud noise. Superior olivary nucleus projects to CN VII - _____________ muscle which:

to CN V - tensor tympani muscle which:

A

stapedius muscle

dampens the noise at the stapes

dampens the noise at the malleus.

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23
Q

Acoustic Neuroma =

A

Tumor growing in the cerebellopontine angle, usually benign and beginning on the VIII nerve.

24
Q

Vestibular component (of acoustic neuroma) =

A

irritative lesion; changes in perception of head position – spinning sensation, vertigo.

25
Q

Tinnitus (ringing of the ears) –>

A

irritative lesion.

26
Q

Which cranial nerves are also involved in acoustic neuroma?

A

CN VII, V, IX

27
Q

Antibiotic toxicity =

A

Some antibiotics are toxic to the CNS (penicillin, streptomyocin). When given for ear infections, they can effect CN VIII specifically. This CN has a “weak” spot in the change from the meninges to the connective tissue component of a peripheral nerve.

28
Q

Trigeminal Nerve CN V =

A

Mixed nerve for general sensation of the face and head area, as well as motor output to the muscles of mastication.

29
Q

The sensory parts of this nerve (CN V) carry the same modalities as those carried in both the:

A

dorsal column system and the spinothalamic tract.

30
Q

What 3 disctributed parts are involved with somatosensation of the anterior 2/3 of the face:

A

V1, V2, V3

31
Q

V1 =

A

ophthalmic division; about the eye

32
Q

V2 =

A

maxillary division; below the eye, about the mouth

33
Q

V3 =

A

mandibular divisions; jaw

34
Q

____________________ neurons innervating the muscles of mastication. Restricted to the ________________ division of CN V. (Motor nucleus of V). Also innervates a couple of other muscles, nerve to the mylohyoid (What muscles?) and tensor tympani.

A

Lower motor

mandibular (V3)

35
Q

Facial Nerve CN VII: Lower motor neurons in motor nucleus of VII innervate _____________ muscles of facial expression, platysma and stapedius.

A

ipsilateral

REVIEW RELATION WITH CN VI.

36
Q

Facial Nerve CN VII:

location -

A

exits at anterolateral part of tegmentum of lower pons.

37
Q

Somatotopic organization of motor neurons in motor nucleus for muscles on half of face. Upper motor neuron innervation (_______________) is ___________ to upper part of face representation; ________________ only to lower part of face representation.

A

corticobulbar

bilateral

contralateral

38
Q

motor neurons (of CN VII) are final common pathway, i.e., lower motor neurons, and therefore a lesion of the nucleus or the fibers result in lower motor neuron signs in the innervated muscles. WHAT ARE THE SIGNS OF LMN LESIONS? ARE THE SIGNS IPSILATERAL OR CONTRALATERAL?

A

?????

39
Q

Preganglionic parasympathetic neurons =

A

located in the reticular formation in the caudal pons

40
Q

tear production =

A

postganglionic cell bodies in pterygopalatine ganglion (lacrimal gland)

41
Q

salivation =

A

postganglionic cell bodies in submandibular ganglia (submandibular and sublingual glands).

42
Q

Taste from anterior 2/3 of tongue from ___________________.

A

chorda tympani

43
Q

rostral part of the SOLITARY NUC. (NTS); NTS project ipsilaterally to ________; to gustatory area of cortex – _____________________.

A

VPM

parietal lobe and insula

44
Q

What synapses in the caudal part of NTS?

A

???

45
Q

Lesions of facial nerve CN VII: Bell’s Palsy =

A

Lower motor neuron deficit to muscles of facial expression.

46
Q

Lesions of facial nerve CN VII: Upper motor neuron lesions =

A

deficit on contralateral lower face only.

WHY?

47
Q

Name 5 symptoms of lesions:

A
  1. Lower motor neuron deficit of ipsilateral face.
  2. Dry cornea; ulcerated cornea.
  3. Loss of taste over ipsilateral ant. 2/3 of tongue.
  4. Inability to produce saliva.
  5. Hyperacusis - stapedius can’t dampen sound.
48
Q

What is the only lower motor deficit of muscles of facial expression?

A

Bell’s Palsy

49
Q

Corneal Blink Reflex (follow on schematic) innvervated by :

A

Trigeminal and Facial Nerve.

50
Q

Blink reflex - touch the cornea and both eyes close.

  1. direct reflex =
  2. indirect or consensual response =
A
  1. direct reflex = closure of the touched eye.

2. indirect or consensual response = closure of the untouched eye.

51
Q

Circuits of Blink Reflex: receptor =

A

free nerve ending in cornea (peripheral process of sensory neuron in the ophthalmic division of CN V (elicit with cotton wisp).

52
Q

Circuits of Blink Reflex: afferent limb =

A

central process ends in main sensory nucleus of V.

53
Q

Circuits of Blink Reflex: interneurons in main sensory nucleus V project _____________________________________

A

directly to ipsilateral facial motor nucleus and to RF interneurons.

54
Q

Circuits of Blink Reflex: direct reflex efferent limb =

A

ipsilateral facial motor nucleus to orbicularis oculi - BLINK.

55
Q

Circuits of Blink Reflex: indirect reflex efferent limb =

A

RF interneurons project to contralateral facial motor nucleus to activate contralateral orbicularis oculi - BLINK

56
Q

Circuits of Blink Reflex: effects of lesions = Be able to identify whether the direct or consensual blink reflex is present with each of the identified lesions (A-E).

A

Be able to identify whether the direct or consensual blink reflex is present with each of the identified lesions (A-E).

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