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Neuroscience Exam 4 > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

trigeminal (V) innervates

deficits

A
  • dura
  • entire 1/2 of face including cornea, oral cavity and nasal mucosa (ophthalmic, maxillary, and mandibular divisions of the nerve)

ipsilateral decreased/impaired sensation

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2
Q

facial (VII) innervates

deficits

A

small piece form behind the ear

ipsilateral decreased/impaired sensation

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3
Q

glossopharyngeal (IX) innervates

deficits

A
  • back of tongue
  • upper pharynx

ipsilateral decreased/impaired sensation

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4
Q

vagus (X) innervates

deficits

A
  • lower pharynx
  • layrnx
  • esophagus

ipsilateral decreased/impaired sensation

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5
Q

deficits associated with lesion in pons - chief sensory nucleus (of trigeminal)

A

decreased/impaired touch sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, and esophagus
ipsilateral deficits

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6
Q

deficits associated with lesion in pons - ventral trigeminothalamic tract

A 
decreased/impaired pain and temperature sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, esophagus
contralateral deficits (crossing occurs lower down)
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7
Q

deficits associated with lesion in medulla - spinal trigeminal nuclei and tract

A

decreased/impaired pain and temperature sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, and esophagus
ipsilateral deficits
lesion in medulla ONLY affects nuclei (not crossing pain/temp fibers)

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8
Q

deficits associated with lesion in sensory ascending pathway

A

decreased/impaired touch AND pain and temperature sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, and esophagus
contralateral deficits

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9
Q

2 cranial nerves involved with taste

A

Facial (CN VII): anterior 2/3 of tongue and soft palate

Glossopharyngeal (CN IX): posterior 1/3 of tongue

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10
Q

structures and general path for taste sensation from the nerve to the cortex

A

axons from CN VII and IX terminate in the gustatory nucleus which is the rostral portion of the nucleus of the solitary tract
this is in the pons
axons from this nucleus will synapse on cells in the VPM of the thalamus
from there, axons go through the internal capsule to the cortical area for taste in the parietal lobe (postcentral gyrus).
note: fibers also project from the gustatory nucleus to the hypothalamus and limbic system for autonomic and emotional responses to taste

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11
Q

why taste is seldom affected by unilateral lesions

A

because taste is communicated bilaterally
this is more or less the same reason you are not likely to have clear cut hearing deficits from lesions in the auditory system if they occur rostral to the superior olivary nucleus (to throwback to the previous unit)

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12
Q

which 2 nerves are involved in visceral sensation

A

glossopharyngeal and vagus

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13
Q

type of info glossopharyngeal receives

A

oxygen tension and BP from carotid sinus and carotid body

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14
Q

type of info vagal receives

A

oxygen tension and BP from in the aortic arch and in the aortic bodies and all sensation from sensory receptors in the trachea, bronchi, lungs, heart, stomach and intestines

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15
Q

what structures receive visceral sensory info

A

reticular formation in medulla and pons - for cardiovascular and respiratory control

nucleus of the solitary tract (portion in medulla) - cardiovascular control and other autonomic functions

hypothalamus - to regulate autonomic nervous system

cortex - for conscious awareness of some of these sensations

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16
Q

why visceral sensation is seldom affected by unilateral lesions

A

this is because visceral sensation, like taste and hearing, is communicated bilaterally

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17
Q

which 4 cranial nerves are involved in parasympathetic autonomic functions

A

Oculomotor (CN III) - constriction of the pupil and focusing on a near object

Facial (CN VII) - salivation and lacrimation

Glossopharyngeal (CN IX) - parotid gland for salivation

Vagus (CNX) - parasympathetic cardiac and visceral functions (heart rate, BP, breathing, etc)

18
Q

location and deficits of lesion in automatic nucleus - Edinger Westphal nuclei in the midbrain

A

CN III
ipsilateral

Lesion in the midbrain or the nerve: results in impaire constriction of the pupil and decreased ability to focus on a near object

19
Q

location and deficits of lesion in automatic nucleus - Lacrimal and superior salivatory nuclei in the pons

A

CN VII
ipsilateral

Lesion in the pons or the nerve: results in decreased lacrimation and decreased salivation

20
Q

location and deficits of lesion in automatic nucleus - Inferior salivatory nuclei in The open medulla

A

CN IX
ipsilateral

Lesion in the open medulla or the nerve: results in decreased salivation

21
Q

location and deficits of lesion in automatic nucleus - Dorsal nuclei of the vagal nerve in the open and closed medulla

A

CN X
ipsilateral

Lesion in the open or closed medulla or the nerve: may result in
cardiac arrhythmias, constipation, urinary incontinence

22
Q

s/s lesion in oculomotor nerve/nuclei

A

LMN signs and symptoms in all muscles supplied - this does NOT include lateral rectus or superior oblique
lateral deviation of ipsilateral eye
can’t track medially
ptosis
diplopia
all reflexive movement of that eye to sound, light, etc. are lost

23
Q

s/s lesion in trochlear nerve/nuclei

A

diplopia when looking down and in

LMN signs and symptoms in superior oblique

24
Q

s/s lesion in trigeminal nerve/motor nuclei

A

LMN signs and symptoms in muscles of mastication, tensor tympani, mylohyoid, ant. digastric
decreased sound reflex

25
Q

s/s lesion in abducens nerve/nuclei

A

LMN signs and symptoms in lateral rectus
diplopia
ipsilateral eye is deviated medially
reflexive eye movements to all stimuli lost

26
Q

s/s lesion in facial nerve/nuclei

A

LMN signs and symptoms in all muscles of facial expression, platysma, stylohyoid, post. digastric, stapedius
inability to close eye
weakness evident in entire side of face (upper and lower)
LMN dysarthria
drooling
loss of blink reflex to all stimuli
decreased sound reflex – sounds perceived as louder

27
Q

s/s lesion in glossopharyngeal nerve/nucleus ambiguus

A

LMN signs and symptoms in stylopharyngeus muscle
dysphagia
dysarthria
gag reflex is impaired

28
Q

s/s lesion in vagus nerve/nucleus ambiguus

A 
LMN signs and symptoms in muscles of pharynx, soft palate, larynx, esophagus
dysphagia
dysarthria
hoarse Voice
gag reflex is impaired
29
Q

s/s lesion in spinal accessory/cervical spinal cord ventral horn

A

LMN signs and symptoms in sternocleidomastoid, trapezius

Hypoglossal Nerve/Nuclei

30
Q

s/s lesion in hypoglossal nerve/nuclei

A

LMN signs and symptoms in muscles of the tongue
LMN dysarthria
dysphagia
difficulty chewing and sucking
tongue deviates ipsilateral to lesion (toward weakness)

31
Q

corticobulbar tracts lesions in CNs

A

CN V: descending bilateral corticobulbar fibers for voluntary movement
CN VII: crossed corticobulbar fibers to alpha motor neurons contacting the lower facial muscles (crossing in the pons) and bilateral corticobulbar fibers to alpha motor neurons that innervate the muscles in the upper face
CN IX and X: descending bilateral corticobulbar fibers for voluntary movement
CN XII: crossed corticobulbar fibers (crossing in medulla)

32
Q

Lesions in Corticobulbar Pathway ABOVE the Pons

A

lower face: UMN signs and symptoms on contralateral side
tongue: UMN signs and symptoms, tongue deviates toward weakness, dysarthria
upper face, pharynx, larynx – NO UMN s/s = b/c BILATERAL, also no dysphagia
all reflexes from nuclei in the pons and medulla are still intact
reflexes in the midbrain are only affected if lesion is in midbrain

33
Q

Lesion in Corticobulbar Pathway IN the Pons

A

no UMN problems in upper or lower face
tongue: contralateral UMN signs and symptoms, tongue deviates toward weakness, dyarthria
pharynx, larynx, etc. - no UMN s/s = b/c BILATERAL, also no dysphagia
all reflexes from nuclei in the midbrain and medulla are intact
reflexes in the pons related to function of CN nuclei are lost
decreased sound reflex – perceive things louder
reflexive eye movements to stimuli lost
loss of blink reflex to all stimuli

34
Q

lesion in medulla

A

no UMN deficits in face or tongue

35
Q

pupillary light reflex

A

afferents travel from optic nerve to Edinger Westphal nucleus in midbrain bilaterally
efferents travel from both nuclei through CN III to constrict bilateral pupils
direct response = constriction in ipsilateral eye
consensual response = constriction in contralateral eye

36
Q

lesions in pupillary light reflex

A

lesion in one optic nerve
neither eye can restrict in response to light that shines in that eye
lesion in one EW nucleus
that eye cannot constrict no matter which eye the light is in
the other eye has intact pupillary light reflex to light that shines in either eye

37
Q

which structures are involved in the accommodation reflex

A

necessary to focus your eyes on near objects
lesion in EW nucleus or CN III will impair this ability
afferents travel from occipital visual cortex to bilateral EW and CN III motor nuclei
efferents exit brainstem in CN III to medially converge eyes and increase lens thickness
response produces medial deviation of both eyes - innervates medial rectus through motor nuclei
changes lens shape to focus on the object (through EW)

38
Q

frontal eye fields

A

cells in frontal eye fields send axons down through internal capsule
axons synapse on cells in superior colliculus of midbrain
cross midline and travel in tectobulbar tract to pontine paramedian reticular formation in pons
right frontal eye field activates the eyes to look to the left
left frontal eye field activates the eyes to look to the right

39
Q

lesions in frontal eye fields

A

eyes deviate toward side of lesion
eyes deviate away from side of body that is paralyzed due to involvement of the primary motor cortex
pt unable to gaze voluntarily towards paralyzed extremities

40
Q

pontine paramedian reticular formation

A

center for coordinating lateral gaze located in the pons
coordinates medial rectus of one eye with lateral rectus of other
through medial longitudinal fasciculus coordinates:
excitation and inhibition of ipsilateral abducens
excitation and inhibition of contralateral oculomotor nuclei
right PPRF will coordinates eyes to look to the right
left PPRF will coordinate eyes to look to the left

41
Q

lesions in pontine paramedian reticular formation

A

eyes deviate away from lesion

eyes deviate toward side of body paralysis (damaged corticospinal)

Neuroscience Exam 4 (8 decks)

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