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Neuroscience Exam #2 > Cranial Nerves - Medulla > Flashcards

Cranial Nerves - Medulla Flashcards

1
Q

The medulla is the site of a number of nuclei associated with what cranial nerves?

A

VIII, IX, X, XI, XII

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2
Q

What CN is a motor nerve that supplies both the intrinsic and extrinsic muscles of the tongue?

A

Hypoglossal nerve (CN XII)

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3
Q

Where are the cell bodies of the lower motor neurons located?

A

the hypoglossal nucleus, located near the midline fo the medulla (ventral to the central canal or 4th ventricle)

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4
Q

The axons of the hypoglossal nerve pass in which direction and next to what two structures?

A

the axons pass inferolateral next to the medial lemniscus and pyramid

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5
Q

The axons of the hypogloassal nerve exit the medulla as rootlets in what?

A

the ventrolateral (preolivary) sulcus

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6
Q

Corticobulbar fibers (upper motor neurons) for the hypoglossal nerve arise from where and terminate where?

A

arise from the tongue region of the precentral gyrus and descend with the corticospinal tract to the medulla where most of the fibers cross midline and synapse in the contralateral hypoglossal nucleus

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7
Q

The hypoglossal nucleus receives indirect sensory information from what two nuclei by way of what?

A

receives indirect sensory information from solitary nucleus (taste) and sensory trigeminal nuclei bolus of food in the oral cavity) by way of multisynaptic connections in the reticular formation

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8
Q

This reflex pathway controlling the tongue is involved in what 3 actions?

A
  • swallowing
  • suckling
  • chewing
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9
Q

What results clinically from a lower motor neuron lesion of the hypoglossal nerve or nucleus?

A

paralysis and muscle wasting of both the intrinsic and extrinsic muscles on the ipsilateral side

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10
Q

What happens upon protrusion of the tongue with a LMN lesion of the hypoglossal nerve?

A

the tongue will deviate toward the side of the lesion due to unopposed action of the intact contralateral genioglossus muscle

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11
Q

What results from an upper motor neuron lesion of the hypoglossal nerve that occurs at a level prior to the crossing?

A

weakness of only the extrinsic muscles (primarily genioglossus) on the side contralateral to the side of the lesion

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12
Q

Which cranial nerve is important in identifying the level of lesions (strokes) in the medulla?

A

hypoglossal nerve

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13
Q

A lesion of a paramedian branch of the anterior spinal artery may result in damage to what 4 things?

A
  • hypoglossal nerve fibers
  • the adjacent pyramid
  • medial lemniscus
  • ventral trigeminothalamic tract
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14
Q

A lesion of a paramedian branch of the anterior spinal artery results in a lower motor neuron symptom involving what? Is it ipsilateral or contralateral?

A

lower motor neuron symptom involving the tongue (ipsilateral)

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15
Q

A lesion of a paramedian branch of the anterior spinal artery results in an upper motor neuron symptom involving what? Is it ipsilateral or contralateral?

A

upper motor neuron symptoms involving the pyramid (contralateral)

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16
Q

What is the term that refers to a form of hemiplegia that has an ipsilateral and contralateral presentation in different parts of the body (occurs where a motor cranial nerve exits along the midline adjacent to the descending corticospinal fibers)?

A

alternating hemiplegia

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17
Q

Does a lesion to the paradmedian branch of the anterior spinal artery result in both a LMN an UMN deficit or just one?

A

Both (deficits to both is referred to as alternating hemiplegia)

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18
Q

The lower motor neurons of the cranial component of spinal accessory nerve (XI) are found where and innervate what?

A

located in nucleus ambiguus and innervate a few of the laryngeal muscles (cranial component)

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19
Q

The lower motor neurons of the spinal component of spinal accessory nerve (XI) are found where and innervate what?

A

located in the cervical levels of the spinal cord (dorsal to the ventral horn) and innervate the SCM and trapezius muscles

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20
Q

The axons of the spinal component of CN XI leave the spinal cord and ascend into the cranial cavity to re-exit the skull as what?

A

accessory nerve

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21
Q

For the cranial component of CN XI, a smaller number of fibers exit the medulla along with what nerve?

A

vagus nerve

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22
Q

The UMNs (corticobulbar fibers) of CN XI descend with the corticospinal fibers, decussate where and terminate where?

A

decussate at the pyramidal decussation and terminate in the cervical region (C2-4)

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23
Q

Clinically, how do you test for the involvement of the spinal part of CN XI?

A

ask the patient to turn the head (SCM) or shrug the shoulders (trapezius)

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24
Q

The cranial component of CN XI is indistinguishable with what other nerve?

A

vagus nerve

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25
Q

The lower motor neurons of vagus nerve are located where and innervate what?

A

located in nucleus ambiguus and innervate skeletal muscles of the soft palate, larynx and pharynx, including vocalis muscle (true vocal folds)

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26
Q

Where is the nucleus ambiguus located?

A

in the reticular formation

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27
Q

Nucleus ambiguus contains lower motor neurons for which cranial nerves?

A

CN X and IX, and the cranial part of CN XI

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28
Q

The preganglionic parasympathetic cell bodies of vagus nerve are located primarily in what?

A

in the dorsal motor nucleus of CN X

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29
Q

The axons of the preganglionic parasympathetic cell bodies of the vagus nerve exit the medulla as rootlets of X and synapse on what?

A

synapse on postsynaptic neurons in visceral walls of glands, cardiac muscle and smooth muscle of the thorax and abdomen

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30
Q

Sensory fibers of the vagus nerve travel along what to end in what?

A

travel along the solitary tract to end in the solitary nucleus

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31
Q

Sensory fibers of the vagus nerve carry what kind of information from where?

A

carry pain and pressure from pharynx, larynx, and thorax and abdomen

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32
Q

Some of the sensory fibers of the vagus nerve might enter what nucleus?

A

spinal trigeminal nucleus (pain sensation to the face)

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33
Q

UMNs of vagus nerve innervate what bilaterally?

A

nucleus ambiguus

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34
Q

Is a unilateral lesion of the UMN of the vagus nerve easily noticed?

A

NO (due to the bilateral innervation)

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35
Q

Several important reflexes are carried via parts of what nerve?

A

vagus nerve

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36
Q

The vagus nerve carries what part of the carotid sinus reflex to the heart?

A

efferent part

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37
Q

The afferent limb of the carotid sinus reflex originates from where?

A

originates from the baroceptors along the carotid artery near the bifurcation into internal and external carotid arteries

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38
Q

The afferent information of the carotid sinus reflex is carried by what fibers to which nucleus and then relayed where?

A

carried by fibers of the CN IX to the solitary nucleus, then relayed to the dorsal motor nucleus of X

39
Q

The efferent limb of the carotid sinus reflex arc innervates what to do what?

A

innervates the heart to slow the heart rate

40
Q

The carotid body reflex uses what cranial nerve to carry one sensory (afferent) component?

A

CN X

41
Q

What is the sensory (afferent) component of the carotid body reflex?

A

the chemoreceptor sensation from lung bronchioles

42
Q

Where does the sensory (afferent) component of the carotid body reflex synapse?

A

in the “medullary respiratory center” (an area in the reticular formation)

43
Q

What does the carotid body reflex help to control?

A

breathing rhythm

44
Q

The efferent limb of the carotid body reflex descends to spinal cord levels to control what?

A

inspiration (intercostals and diaphragm)

45
Q

The cough, gag, and vomiting reflexes involve sensory fibers from what two areas of the body and what two cranial nerves?

A
  • oral/nasal cavity (CN IX)

- the gut (CN X)

46
Q

Sensory information of the cough, gag, and vomiting reflexes is relayed to appropriate LMNs in what nucleus/areas?

A
  • nucleus ambiguus
  • spinal cord
  • preganglionic parasympathetics in dorsal motor nucleus of CN X
47
Q

Lesions of CN X result in sensory deficits, motor deficits, or both?

A

both sensory and motor deficits

48
Q

Unilateral lesions of LMNs in CN X results in what?

A

difficulty in swallowing, hoarseness [dysphonia], inability to raise the soft palate on the ipsilateral side

49
Q

Lesions of the preganglionic parasympathetic fibers of CN X cause disruption of what?

A

disruption of some gut reflexes

50
Q

Hyperactivity (excess firing) of preganlgionic parasympathetic fibers of CN X can cause what?

A

excess gastric acid secretion = ulcers

51
Q

Large bilateral lesions of the medullary reticular formation can disrupt what?

A

normal breathing rhythms and reflex control of vascular resistance to blood flow and result in coma

52
Q

LMNs of glossopharyngeal nerve (CN IX) innervate what muscle?

A

stylopharyngeus muscle

53
Q

Where are the LMNs of CN IX located?

A

rostral end of nucleus ambiguus

54
Q

What cranial nerves have LMNs in nucleus ambiguus?

A

IX, X, XI

55
Q

Where are the preganglionic parasympathetic cell bodies of CN IX located?

A

reticular formation

56
Q

Preganglionic parasympathetic axons of CN IX exit the medulla to synapse with what? which then innervates what?

A

synapse on postganglionic neurons in otic ganglion which then innervates the parotid gland

57
Q

The preganglionic parasympathetic axons of CN IX follows what branch of V3?

A

auriculotemporal

58
Q

Sensory neurons of CN IX synapse where?

A

caudal part of the solitary nucleus and sensory trigeminal nuclei (spinal nucleus of V)

59
Q

The sensory neurons of CN IX that synapse in solitary nucleus carries what kind of information?

A

afferent limb of the carotid sinus reflexes

60
Q

The sensory neurons of CN IX that synapse in trigeminal nuclei carry what kind of information?

A
  • somatic sensations (touch, pressure, pain) from pharynx and posterior 1/3 of tongue [gag reflex]
  • taste sensation (primarily bitter) from posterior 1/3 of tongue to anterior part of solitary nucleus
61
Q

Cortical control (UMN) of CN IX in cortex descends as part of what system to synapse where?

A

descends as part of corticobulbar system to synapse bilaterally on LMN’s in nucleus ambiguus

62
Q

CN IX carries the afferent (sensory) limb for which reflexes?

A

carotid sinus, gag, swallowing, and vomiting reflexes (all of which have an efferent limb carrired by either CN X, XII, and/or spinal cord LMNs)

63
Q

The motor components of CN IX participate in what reflex?

A

taste reflexes (swallowing and salvation)

64
Q

Unilateral lesions of CN IX can produce difficulty with what?

A

difficulty with speech and swallowing

65
Q

Are CN X lesions more severe than CN IX lesions?

A

YES

66
Q

What is the most diagnostic deficit with a lesion to CN IX?

A

loss of gag reflex to touching the pharynx (afferent limb)

67
Q

What is the most diagnostic deficit with a lesion to CN X?

A

deviation of uvula (efferent limb)

68
Q

What is the most lateral cranial nerve?

A

vestibulcochlear nerve

69
Q

What is the most medial cranial nerve?

A

facial nerve at the level of the pons

70
Q

What part of the medulla is closed?

A

caudal

71
Q

What part of the medulla is open?

A

rostral

72
Q

The most medial pieces are the motor or sensory pieces most specific to the nuclear groups of the medulla?

A

motor

73
Q

The most medial pieces (motor) most specific to the nuclear groups of the medulla include what 3 nuclei?

A
  • hypoglossal nuclei
  • nucleus ambiguus
  • dorsal motor nucleus of the vagus
74
Q

Which nucleus gives rise to parasympathetic component of the vagus nerve?

A

dorsal motor nucleus of the vagus

75
Q

The most lateral pieces (lateral to sulcus limitans) are the motor or sensory pieces most specific to the nuclear groups of the medulla?

A

sensory

76
Q

The most lateral pieces (sensory) most specific to the nuclear groups of the medulla include what 4 nuclei?

A
  • solitary nuclei
  • vestibular nuclei
  • spinal trigeminal nuclei
  • cochlear nuclei
77
Q

Which part of the solitary nucleus (caudal or rostral) takes incoming visceral information and distributes it where it needs to go?

A

caudal

78
Q

Which part of the solitary nucleus (caudal and rostral) has more to do with receiving the sensation of taster and relaying it out to the appropriate places?

A

rostral

79
Q

The internal arcuate fibers (neurons) leave the dorsal column nuclei, cross midline, and form what?

A

medial lemniscus

80
Q

What is the piece that is the descriptor between rostral and caudal medulla?

A

the fourth ventricle

81
Q

What are the nuclei and pathways involved in lateral medullary syndrome?

A
  • vestibular nuclei
  • inferior cerebellar peduncle
  • central tegmental tract
  • lateral spinothalamic tract
  • spinal trigeminal nucleus
  • nucleus ambiguus
82
Q

A deficit to vestibular nuclei results in what?

A

vomiting, vergo, nystagmus

83
Q

A deficit to the inferior cerebellar peduncle results in what?

A

ipsilateral cerebellar signs (ataxia)

84
Q

A deficit to the central tegmental tract results in what?

A

palatal myoclonus

85
Q

A deficit to the lateral spinothalamic tract results in what?

A

contralateral deficits in pain and temperature sensation from body (limbs and torso)

86
Q

A deficit to the spinal trigeminal nucleus results in what?

A

ipsilateral loss of pain, and temperature sensation from face

87
Q

A deficit to the nucleus ambiguus results in what?

A

ipsilateral laryngeal, pharyngeal, and palatal hemiparalysis: dysphagia, hoarseness, diminished gag reflex (efferent limb - CN.X)

88
Q

What are the nuclei and pathways involved in medial medullary syndrome?

A
  • hypoglossal nerve
  • medullary pyramid and hence to the corticospinal fibers of the pyramidal tract
  • medial lemniscus
89
Q

A deficit to the hypoglossal nerve fibers would result in what?

A

a deviation of the tongue to the side of the infarct on attempted protrusion, caused by ipsilateral muscle weakness.

90
Q

A deficit to the medullary pyramid would result in what?

A

limb weakness (or hemiplegia, depending on severity), on the contralateral side of the infarct

91
Q

A deficit to the medial lemniscus would result in what?

A

a loss of discriminative touch, conscious proprioception, and vibration sense on the contralateral side of the infarct

92
Q

Incoming auditory information come into what 2 nuclei?

A

cochlear nuclei and vestibular nuclei

93
Q

Vagal fibers and glossopharengeal fibers exit the medulla above or dorsal to what structure?

A

inferior olivary complex

94
Q

Hypoglossal fibers exit the medulla adjacent to what?

A

the pyramids

Neuroscience Exam #2 (8 decks)

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