Exam #2: Cranial Nerves IV Flashcards

1
Q

List the five functional components of the facial nerve (CN VII).

A

1) SVE
2) SVA
3) GVE
4) GSA
5) GVA

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2
Q

What is the SVE component of the facial nerve?

A

Brachimotor innervation (motor) to the muscles of facial expression

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3
Q

What are the muscles of facial expression that are innervated by the facial nerve (CN VII)?

A
Platysma
Posterior belly of digastric
Stylohyoid 
Stapedius 
Auricularis
Occipitalis muscles
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4
Q

What is the SVA function of the facial nerve (CN VII)?

A

Taste from the anterior 2/3 of the tongue

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5
Q

What is the GVE function of the facial nerve (CN VII)?

A

PNS to the:

  • Lacrimal
  • Nasal
  • Palatine
  • Submandibular
  • Sublingual glands
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6
Q

What is the GSA function of the facial nerve (CN VII)?

A

General sensation from the skin:

  • Posterior to the ear
  • Pinna
  • External auditory meatus
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7
Q

What is the GVA function of the facial nerve (CN VII)?

A

Visceral sensation from the:

  • Nasal cavity
  • Soft palate
  • Adjacent pharyngeal wall
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8
Q

Where does the facial nerve emerge from the brain?

A

Ventrally at the Cerebello-pontine angle–which is lateral to the abducens

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9
Q

What are the two roots of the facial nerve?

A

1) Facial nerve proper i.e. motor branch

2) Nervus intermedius

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10
Q

What specifically does the “Facial Nerve Proper” consist of?

A

Axons whose cell bodies originate from the facial nucleus

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11
Q

What is the function of the “Nervus Intermedius?”

A
  • SVA, GSA, & GVA from neurons originating in the geniculate nucleus
  • GVE from the superior salivary nucleus
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12
Q

Where does the facial nerve initially pass through as it leaves the brain? What nerve accompanies it?

A

The facial nerves passes through the internal acoustic meatus w/ vestibulocochlear nerve to enter the facial canal

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13
Q

Where is the internal acoustic meatus?

A

Petrous portion of the temporal bone in the skull

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14
Q

What is the swelling of the facial nerve in the facial canal?

A

Geniculate ganglion, which is the ONLY sensory ganglion of the facial nerve

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15
Q

What is the name of the sensory ganglion associated with the facial nerve?

A

Geniculate ganglion

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16
Q

What are the names of the two PNS ganglia associated with the facial nerve?

A

1) Pterygopalatine ganglion

2) Submandibular ganglion

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17
Q

What does the Pterygopalatine ganglion consist of?

A

Cell bodies of post-synaptic PNS neurons terminating in the:

1) Lacrimal gland
2) Nasal mucous membrane
3) Minor salivary gland

*****Note that b/c of this the Pterygopalatine ganglion is also referred to as the “hay fever ganglion.”

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18
Q

What are the functions of the Pterygopalatine ganglion?

A

1) Lacrimal gland= tear formation
2) Nasal mucous membrane= nasal secretions
3) Minor salivary gland= salivary secretion

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19
Q

What does the Submandibular ganglion consist of?

A

Cell bodies of post-synaptic PNS neurons terminating in the:

1) Submandibular gland
2) Sublingual gland

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20
Q

What is the function of the Submandibular ganglion?

A

Submandibular gland & sublingual gland are BOTH involved in salivation

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21
Q

What is the chorda tympani?

A
  • Nerve that carries taste sensation from the anterior 2/3 of the tongue
  • Joins the facial nerve (cranial nerve VII) inside the facial canal
22
Q

What is the nerve to the stapedius?

A
  • Part of the facial nerve that innervates the stapedius m.

- Functions to dampen loud noises

23
Q

What happens when the stapedius is paralyzed?

A

Hyperacusis

24
Q

Through what foramen does the facial nerve exit the skull?

A

Stylomastoid foramen

25
Q

What are the three nuclei associated with the facial nerve?

A

1) Facial
2) Superior salivary
3) Solitary

26
Q

What does the facial nucleus contain?

A

Cell bodies of motor neurons (LMNs)

27
Q

What does the superior salivatory nucleus contain?

A

Cell bodies of pre-synaptic PNS neurons that synapse with the:

1) Pterygopalatine ganglia
2) Submandibular ganglia

28
Q

What does the solitary nucleus contain?

A

This is the nucleus that receives the central processes of taste fibers from the tongue

29
Q

What is crocodile/ aligator tear syndrome?

A

Lesion in the facial nerve proximal to the geniculate ganglion

  • Pre-ganglionic axons regenerate but make a wrong turn
  • Axons that should go to the submandibular gland via the chorda tympani
  • However, instead they join the greater petrosal nerve & go to t he pterygopalatine ganglion

**When the person starts eating, instead of producing saliva, the person produces tears on the affected side of the face

30
Q

What are the two tracts associated with the facial nerve?

A

1) Solitary Tract

2) Spinal Tract of V

31
Q

What is the Solitary Tract?

A

This is the tract that carries taste sensation from the anterior 2/3 of the tongue to the thalamus & hypothalamus

*****This tract mediates visceral responses (I.E VOMITING) to unpleasant stimuli.

32
Q

What is the Spinal Tract of V?

A
  • **The facial nerve does NOT have a pain nucleus

- Instead it relays nociception from the facial nerve to the spinal tract of V (Trigeminal nerve)

33
Q

What is the only cranial nerve to have a pain nucleus?

A

CN V (Trigeminal)

34
Q

What is the difference between the innervation of the upper & lower halves of the facial nucleus?

A

Upper= bilateral corticonuclear projections

Lower= contralateral corticonuclear projections ONLY

35
Q

What is the pyramidal system? What type of smile is generated by the pyramidal system?

A

Conscious, voluntary control of facial movement that results in an “imitation smile.”

36
Q

What structures do corticonuclear fibers pass through as they descend to the facial nucleus?

A

Genu

Posterior capsule

37
Q

What happens when there is a UMN lesion at the level of the genu?

A

Asymmetric smile

38
Q

What is the alternate pathway to the facial nucleus?

A

This is a pathway distinct from the pyramidal system that goes from:

1) Frontal lobe & basal ganglia
2) Reticular formation
3) Facial nucleus
4) LMN
5) Muscles of facial expression

39
Q

What type of smile is produced by the alternate pathway to the facial nucleus?

A

“Genuine smile”

40
Q

A patient s/p CVA with asymmetric smile has a symmetric smile in response to the sight of his granddaughter. What pathways is responsible for this?

A

CVA caused damage to the pyramidal system but the “Alternate pathway” is intact

41
Q

Outline the corneal blink reflex.

A

Afferent fibers = ophthalmic division of CN V (V.1)

Efferent fibers= CN VII–>orbicularis oculi

42
Q

What is the difference between the direct & concensual pathway?

A

Direct= blink reflex in stimulated eye

Consensual= blinck reflex in unstimulated eye

43
Q

What happens when there is a lesion of V.1 in the blink reflex?

A

Stimulation of affected eye= no blink in either eye

Unaffected eye= bilateral blinking of BOTH eyes

44
Q

What happens when there is a lesion of CN VII in the blink reflex?

A

Affected= blink in opposite eye ONLY

Unaffected= blink in ONLY the stimulated eye

45
Q

How does the pupillary light reflex compare to the corneal light reflex?

A

Pupil=

  • Afferent= optic
  • Efferent= CN III

*****However, other general concepts (esp. in regards to lesions) remain the same

46
Q

Describe the typical presentation of Bell’s Palsy.

A

Complete facial paralysis on the side of the face IPSILATERAL.

47
Q

Is Bell’s Palsy an upper or lower motor neuron lesion?

A

Lower

48
Q

How does the presentation of Bell’s Palsy change if the lesion is in the facial canal vs. distal to the facial canal?

A

In the facial canal=

  • Dry eye
  • Hyperacusis
  • Pain behind the ear
  • Diminished taste sensation

Distal= paralysis ONLY

49
Q

Match the branches of the facial nerve that are effected to the symptoms of: dry eye, hyperacusis, pain behind the ear, & diminished taste sensation seen in Bell’s Palsy w/ lesion in the facial canal.

A
  • Dry eye= petrosal
  • Hyperacusis= nerve to stapedius
  • Pain behind the ear= posterior auricular (geniculate ganglion)
  • Diminished taste sensation= chorda tympani
50
Q

How will a UMN lesion affecting the facial nerve present?

A

Paralysis of the face BELOW THE EYE on the CONTRALATERAL side, without facial canal lesion symptoms