Facial nerve Flashcards

1
Q

Fibres of facial nerve

A
  • General somatic afferent (GSA)
  • Special visceral afferent (SVA)
  • General visceral efferent (GVE)
  • Special visceral efferent (SVE, brachiomotor)
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2
Q

Origin of facial nerve

A

Cerebellopontine angle(motor and sensory roots)

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3
Q

Facial nerve exits skull through

A

Stylomastoid foramen

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4
Q

Facial nerve nuclei

A
  • Motor nucleus of facial nerve (SVE)
  • Superior salivatory nucleus (GVE)
  • Nucleus of solitary tract (SVA)
  • Principal sensory nucleus of trigeminal nerve (GSA)
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5
Q

Associated ganglia of facial nerve

A

Geniculate ganglion(pterygopalatine ganglion, otic ganglion, submandibular ganglion)

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6
Q

What are the main parts of the facial nerve

A
  • Intracranial
  • Intratemporal
  • Extracranial
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7
Q

Parts and branches of the intracranial part of the facial nerve

A

Origin-> Internal accoustic meatus(no branches)

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8
Q

Parts and branches of the Intratemportal part of the facial nerve

A
  • Internal accoustic meatus-> Stylomastoid foramen
  • Greater petrosal nerve
  • Nerve to stapedius muscle
  • Chorda tympani
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9
Q

Parts and branches of the Extracranial part of the facial nerve

A
  • After stylomastoid foramen
  • Posterior auricular nerve
  • Digastric branch
  • Stylohyoid branch
  • Parotid plexus(Temporal, Zygomatic, Buccal, Marginal, cervical)
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10
Q

Main functions of facial nerve

A
  • Motor innervation to muscles of facial expression (SVE)
  • Taste to anterior two thirds of tongue and palate (SVE)
  • Parasympathetic innervation of lacrimal, nasal, palatine and salivary glands(except parotid)(GVE)
  • Sensation to part of auricle and retroauricular region
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11
Q

Sensations of facial nerve

A
  • Motor and sensory
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12
Q

Intracranial course of Facial nerve

Origin of motor root of facial nerve

A
  • Motor nucleus of facial nerve at lower pontine tegmentum
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13
Q

Intracranial course of Facial nerve

Merge with fibres of the **superior salivatory nucleus **and then pass to floor of fourth ventricle

A

Motor root axons

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14
Q

Intracranial course of Facial nerve

  • The motor root axons loop around the nucleus of this nerve before exiting brainstem at the cerebellopontine angle
A

Abducens nerve

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15
Q

Intracranial course of Facial nerve

Fibres of the sensory root travel towards this structure to reach the nucleus of solitary tract

A

Medulla

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16
Q

Intracranial course of Facial nerve

Nucleus of solitary tract

A

Visceral sensory part of brainstem involved with relaying signals of satiety

Further fibers projected to principal sensory nucleus of trigeminal nerve

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17
Q

Intratemporal course of Facial nerve

Facial nerve roots course as they leave cranial cavity

A

Via **internal acoustic meatus **to enter facial canal in petrous part of temporal bone

Here they fuse to form facial nerve proper

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18
Q

Intratemporal course of Facial nerve

Facial nerve roots make sharp anterior to posterior turn at this point

A

Geniculum of facial nerve

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19
Q

Intratemporal course of Facial nerve

Facial nerve roots enlarge at this point

A

Geniculate ganglion

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20
Q

Intratemporal course of Facial nerve

Contains the cell bodies of the sensory neurons of the facial nerve

A

Geniculate ganglion

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21
Q

Intratemporal course of Facial nerve

Arises directly from the geniculate ganglion

A

Greater petrosal nerve

22
Q

Intratemporal course of Facial nerve

Arise before the facial nerve exits the temporal bone

A
  • Nerve to stapedius muscle
  • Chorda tympani
23
Q

Extracranial course of Facial nerve

Facial nerve leaves facial canal through this foramen

A

Stylomastoid foramen

24
Q

Extracranial course of Facial nerve

After exiting through stylomastoid foramen, the facial nerve gives off this nerve before entering the parotid gland

A

Posterior auricular nerve

25
Q

Extracranial course of Facial nerve

After giving off the posterior auricular nerve, the facial nerve enters this gland where it has 5 terminal branches

A

Parotid gland

26
Q

Intratemporal branches

On its course to foramen lacerum, merges with deep petrosal nerve carrying sympathetic fibers to form

A

Nerve of the pterygoid canal

27
Q

Intratemporal branches

Greater petrosal nerve innervation

A
  • Travels to pterygopalatine ganglion to provide parasympathetic innervation to:
    * Lacrimal gland
  • Mucous glands of nasal cavity, Maxillary sinus and palate
28
Q

Intratemporal branches

Second intratemporal branch of facial nerve

A

Nerve to stapedius muscle

29
Q

Nerve to stapedius muscle innervation

A
  • SVE/branchiomotor fibres
  • Dampening vibrations and protecting hearing apparatus during exposure to loud sounds
30
Q

Intratemporal branches

Final Intratemporal branch

A

Chorda tympani

31
Q

Intratemporal branches

Traverses middle ear and exits via petrotympanic fissure

A

Chorda tympani

32
Q

Intratemporal branches

The chorda tympani merges with this nerve

A

Posterior aspect of lingual nerve

33
Q

Intratemporal branches

Chorda tympani innervation

A
  • Anterior two thirds of tongue
  • Submandibular and sublingual glands

Salivary secretions

34
Q

Extracranial branches

First Extracranial branch

A

Posterior auricular nerve

35
Q

Extracranial branches

Posterior auricular nerve innervation

A
  • Motor-> occipitofrontalis muscle
  • Intrinsic auricular muscles
  • Skin around external acoustic meatus and retroauricular region
36
Q

Extracranial branches

Digastric and stylohyoid innervation

A

Motor to there respective muscles

37
Q

Extracranial branches

Facial nerve pierces parotid gland and bifurcates into

A

Superior and inferior trunks which give rise to five terminal branches

38
Q

Extracranial branches

Terminal branches of facial nerve

A

To Zanzibar By Motor Car
* Temporal
* Zygomatic
* Buccal
* Marginal mandibular
* Cervical

39
Q

To Zanzibar By Motor Car

Temporal branch innervation

A
  • Frontalis
  • Orbicularis occuli
  • Currugator supercilii muscles
40
Q

To Zanzibar By Motor Car

Zygomatic branches innervation

A
  • Orbicularis oculi muscle
41
Q

To Zanzibar By Motor Car

Buccal branches innervation

A
  • Orbicularis oris
  • Buccinator
  • Zygomaticus muscles
42
Q

To Zanzibar By Motor Car

Marginal mandibular branches innervation

A
  • Depressor labii inferioris
  • Depressor anguli oris
  • Mentalis
43
Q

To Zanzibar By Motor Car

Cervical branches innervation

A

Platysma muscle

44
Q

Areas of the facial nerve, lesions can occur

A
  • Intracanial
  • Intratemporal
  • Extracranial
45
Q

Intratemporal facial nerve lesions

Damage to the nerve near its origin, the geniculate ganglion or within facial canal leads to these symptoms

A
  • Loss of motor function
  • Taste and autonomic functions affected
46
Q

Intratemporal facial nerve lesions

Lesions affecting greater petrosal nerve result in

A
  • Impaired lacrimal fluid production ipsilaterally
47
Q

Intratemporal facial nerve lesions

Lesions affecting nerve to stapedius muscle result in

A

Hypersensitivity to sound

48
Q

Intratemporal facial nerve lesions

Lesions affecting chorda tympani

A
  • Reduced salivary secretion of submandibular and sublingual glands
  • Loss of gustatory function of anterior two thirds of tongue ipsilaterally
49
Q

Extracranial facial nerve lesions

After leaving skull, facial nerve damage along extracranial course affects

A

Motor fibres

49
Q

Extracranial facial nerve lesions

Lesions affecting extracranial facial nerve fibres cause

A

Facial nerve palsy-paralysis or weakness in muscles of facial expression

50
Q

Extracranial facial nerve lesions

Extracranial lesions aetiology

A
  • Idopathic-bells palsy
  • Infection-viral(Herpes)
  • Iatrogenic-surgery(removal of parotid)
  • Compression(forceps baby delivery)
51
Q

Sudden ipsilateral facial paralysis with no detectable cause

A

Bells palsy