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Neuro anatomy 2 > CN IV > Flashcards

CN IV Flashcards

1
Q

describe the functional components of CN VII

A
  • SVE = branchiomotor to muscles of facial expression, etc
  • SVA = TASTE from anterior 2/3 of tongue
  • GVE = parasympathetic to glands
  • GSA = general sensation from skin in posterior ear, pinna, external auditory meatus
  • GVA = visceral sensation from nasal cavity,s oft palate, adjacent phayngeal wall
  • Carries its own MOTOR, PARASYMPATHETIC and SENSORY FIBERS
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2
Q

What does the facial nerve proper contains

A
  • Consists of axons of nerve cells whose cell bodies are located in facial (motor) nucleus
  • Motor root, SVE
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3
Q

what are the contents of nervus intermedius root

A
  • central proceses of SVA, GSA and GVA neurons whose cell bodies reside in the geniculate ganglion (general and visceral sensation and Taste)
  • GVE fibers arising from superior salivatory nucleus (parasymapthetic)
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4
Q

descrive geniculate ganglion

A
  • Sensory ganglion
  • contains cell bodies of PSEUDOUNIPOLAR NEURONS (GVA, SVA, GSA)
  • NO synpases
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5
Q

describe pterygopalatine ganglion

A
  • contains cell bodies of POSTGANGLIONIC Parasympathetics (GVE) neurons whose axons terminate in the:

–> lacrimal gland = tear formation - provides moisture and cleans eye

–> nasal mucous membrane = nasal secretions - moistrue to nasal mucosa

–> Minor salivary glands in palate = salivary secretion

**Alligator tears - phenomenon during eating

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6
Q

describe submandibular ganglion

A
  • contains cell bodies of postganglionic parasympathetics (GVE) neurons whose axons termiante in the:

–> submandibular gland (salivation)

–> sublingual gland (salivation)

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7
Q

define facial nucleus

A
  • Motor nuclei
  • Contains cell bodies of motor neurons (LMN’s)
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8
Q

Define superior salivatory nucleus

A
  • Parasymapthetic nuclei
  • contains the cell bodies of PREGANGLIONIC parasympathetic neurons whose axons synapse in pterygopalatine or submandibular ganglia
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9
Q

define solitary nucleus

A
  • sensory nuclei
  • facial nerve shares this nucleus with glossopharyngeal and vagus nerves
  • receives the central processes of SVA (Taste) and GVA neurons (visceral sensation)
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10
Q

describe the solitary tract

A
  • carries central processes of SVA and GVA neurons to solitary nucleus
  • solitary nucleus proceses taste sensation and projects to the hypothalamus which mediates the visceral respones to unpleasant sensation (vomiting)
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11
Q

Desribe spinal tract of the trigeminal nerve

A
  • carries central proceses of GSA neurons to spinal nucleus of trigeminal nerve
  • facial nerve DOESN’T have a pain nucleus so it sends it nociceptive fibers to SPINAL TRACT OF V that terminates in the pain nucleus of V
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12
Q

What type of fibers does the upper half of facial motor nucleus receive

A
  • Receives BILATERAL CORTICONUCLEAR projectons (UMN projections)
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13
Q

What type of fibers does the lower half of facial motor nucleus receive

A
  • receives ONLY CONTRALATERAL CORTICONUCLEAR projections (UMN projections
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14
Q

describe the pattern of innervation of the muslces of facial expression by LMN of facial motor nucleus

A
  • LMN whose cell bodies reside in upper half of facial motor nucleus, innervate muscles of upper half of face
  • LMN whose cell bodies reside in LOWER HALF of facial motor nucleus, INNERVATE muscles of LOWER HALF of face
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15
Q

describe the corneal blinke reflex

A

1) Afferent (sensory) limb of reflex arc = opthalmic division of V
2) Efferent (motor) limb of reflex arc = facial nerve to orbicularis oculi
- Direct corenal reflex = response on side stimualted
- Consensual corneal reflex = response on the other side

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16
Q

Describe the Pyramid system

A
  • CONSCIOUS, voluntary control of movement
  • Influences movement via the UMN of corticonuclear tract
  • UMN of corticonuclear tract –> facial nucleus –> LMN of facial nerve –> muscles of facial expression
17
Q

What is the result of an UMN (corticonuclear fibers) to pyramid system

A
  • Result is an Asymmetrical smile
18
Q

describe an alternate pathway to facial nucleus

A

1) accessory motor areas (frontal lobe) and basal ganglia
2) reticular formation (bilateral projections)
3) facial nucleus
4) LMN carry fibers to muscles of facial expression (smiling: duchenne smile)

–> results in a symmetrical smile despite an UMN lesion

19
Q

What will result in a lesion of first order neuron (trigeminal afferent) of the corneal blink reflex

A
  • If you stimulate cornea of eye 1 (eye with lesion), neither eye will blink
  • If you stimulate cornea of eye 2 (normal), BOTH eyes will blink
20
Q

What is the result of a lesion in the Facial nerve (efferent limb of reflex arc) of corneal blink reflex? (eye 1 has lesion)

A
  • If you stimulate cornea of eye 1, ONLY eye 2 will blink
  • If you stimulate cornea of eye 2, ONLY EYE 2 WILL BLINK
21
Q

Describe the cause of Bell’s Palsy

A
  • Due to LMN lesion

–> the ENTIRE HALF of the face is usually paralyzed, IPSILATERAL TO LESION

22
Q

If a patient is experiencing: Dry eye, hyperacusis, diminished taste sensation, weakness/paralysis in one side of face. Where is the lesion?

A
  • Lesion is in the FACIAL CANAL
  • Greater petrosal nerve (GVE) is affected causing dry eye
  • Nerve to stapedius (SVE) is affected causing Hyperacusis (acute sense of hearing)
  • Geniculate ganglion was affected cuasing pain behind the ear (GSA)
  • Chorda tympai nerve is affected (loss of taste (SVA) in anterior 2/3 of tongue)
23
Q

What do you expect the patient to experience if lesion is located distal to facial canal (after it gives off branches)

A
  • Patient will ONLY Have paralysis in the IPSILATERAL HALF OF FACE
  • facial palsy is chronic, slow and progressive suggesting a slow-gorwing tumor affecting facial nerce branches
24
Q

What are the causes of Bell’s palsy

A
  • viral infection of facial nerve’s connective tissue causes Inflamamtion, edema and consequent swelling of nerve leading to compressing the enclosed nerve fibers

–> resulst in ischemia and compromised conduction of facial nerve fibers

  • Bell’s palsy can have a degree of facial nerve injury from mild to severe (80% make a full recovery)
25
Q

describe the result of bells palsy due to pure demyelinating conduction block (NEUROPRAXIA)

A
  • includes up to 90% of cases
  • nerve cell axons are not lost
  • recovery is quick and complete
26
Q

describe bells palsy due to axonal damage with WALLERIAN DEGENERATION

A
  • includes 10% of cases
  • nerve cell axons are LOST
  • recovery is slow and incomplete
27
Q

describe crocadile tears

A
  • caused by lesion to facial nerve proximal to geniculate ganglion

–> during axonal regeneration, some preganglionic parasympathetic fibers take wrong turn and instead of joining chorda tympani head for submandibular ganglion to synapse there

–> join the greater petrosal nerve to terminate in the pterygopalatine ganglion

  • RESULT = during eating, instead of salivating, tear formation occurs referred to as crocadile tears
28
Q

compare deficits of UMN lesion with LMN lesion of the facial nerve

A

Neuro anatomy 2 (10 decks)

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