peripheral distribution of cn vii-xii Flashcards

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1
Q

what are the fibres of the facial nerve?

A

Branchiomotor Efferent (BE), General Visceral Efferent (GVE), Special Sensory Afferent (SA), General Somatic Afferent (GSA)

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2
Q

what do each of the fibres of the facial nerve innervate?

A

BE: muscles of facial expression, post digastric, stylohyoid & stapedius
GVE: parasympathetic- lacrimal, submandibular and sublingual glands, mucus membranes of nasopharynx
SSA: Taste from anterior 2/3 tongue and palates
GSA: skin of part of external ear and behind

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3
Q

how do the facial nerve fibres exit the skull?

A

through the internal acoustic meatus

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4
Q

what forms the nervus intermedius?

A

all the branches of the facial nerve apart from BE

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5
Q

where does the facial nerve start/originate?

A

the brainstem

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6
Q

describe the course of the facial nerve

A

brainstem –> internal acoustic meatus
branches into the facial canal and petrosal foramen
50% of parasympathetic supply comes off as greater petrosal nerve
other 50% goes down facial canal - joins special sensory to form chorda tymponi
motor component gives innervation to stapedius
leaves through stylomastoid foramen and innervates muscles of facial expression
passes through parotid gland
5 terminal branches

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7
Q

where is the geniculate ganglion found?

A

at the bend of the facial canal and petrosal foramen

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8
Q

what does the greater petrosal nerve innervate?

A

parasympathetic secretomotor to mucous glands and lacrimal glands

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9
Q

what forms the vidian nerve?

A

deep petrosal and greater petrosal

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10
Q

what does the vidian nerve innervate?

A

lacrimal glands and mucous glands

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11
Q

what forms the chorda tymponi nerve?

A

other 50% of parasympathetic fibres of facial nerve and the special sensory supply

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12
Q

what does the chorda tymponi innervate?

A

anterior 2/3 of the tongue

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13
Q

what other nerve runs along the chorda tymponi?

A

lingual nerve

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14
Q

what does the stapedius attach to and what is its function?

A

Attached onto the stapes, stopping it from shaking uncontrollably –> dampens sound

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15
Q

name the 5 terminal branches of the facial nerve (from top to bottom)

A
temporal
zygomatic
buccal
marginal mandibular
cervical
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16
Q

what is bell’s palsy?

A

facial muscle paralysis

LMN lesion

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17
Q

at what point along the LMN can a lesion occur in bell’s palsy?

A

any point

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18
Q

what causes bell’s palsy?

A

Unknown cause – can be due to swelling of nerve in facial canal, puts pressure on the nerve

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19
Q

what are indications/risks of bell’s palsy and why?

A
  • Cornea at risk of drying out –> greater petrosal nerve innervates the lacrimal gland, which controls secretions onto cornea
  • Hyperacusis –> stapedius muscle is affected, you become hypersensitive to sound
  • Loss of taste (ant 2/3rd of tongue) –> chorda tymponi
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20
Q

what is bell’s palsy often confused with?

A

ischemic stroke

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21
Q

how are forehead muscles innervation?

A

bilaterally innervated - dual innervation

UMNs from the right and left cortex synapse in the brain to form LMNs. The LMN innervates the forehead muscles. Therefore, all the forehead muscles are innervated by both sides of the cortex

22
Q

how is the lower half of the face innervated?

A

contralateral innervation

UMN from the right cortex enters the brainstem. The facial nerve is the LMN and innervates the left side of the face.

23
Q

what does an umn lesion lead to?

A

stroke
contralateral weakness of the lower face
forehead muscles are unaffected

24
Q

what does a lmn lesion lead to?

A

bell’s palsy

forehead muscles are affected

25
Q

what are the fibres of the vestibulocochlear nerve?

A

special sensory afferent

26
Q

what are the branches of the vestibulocochlear nerve and what do they control?

A

cochlear branch - hearing

vestibular branch - balance

27
Q

describe the course of the vestibulocochlear nerve

A

• Fibres go from the cochlear and vestibular apparatus through internal acoustic meatus to the brain

28
Q

what is the function of the cochlear?

A

sensory fibres from the cochlear detect the magnitude of sound waves

29
Q

what does the vestibular apparatus do?

A

found in the inner ear and relates info about the position of our head in relation to gravity –> has fluid to help

30
Q

what is the tympanic membrane?

A

the eardrum

31
Q

what fibres make up the glossopharyngeal nerve and what do they innervate?

A

o SA: special taste to posterior 1/3rd of tongue
o GVA: Oropharynx (nerve gives “gag reflex”), carotid bodies (detect O2 and CO2) & carotid sinus (baroreceptors which detect BP), general sensation to posterior 1/3rd of tongue
o GSA: auricle, ext. acoustic meatus, mid ear & eustachian tube
o GVE: parasympathetic to parotid gland (otic ganglion)
o BE: stylopharyngeus muscle

32
Q

where does the glossopharyngeal nerve emerge from?

A

pons then through the jugular foramen

33
Q

what nerve innervates the parotid gland?

A

glossopharyngeal

34
Q

what fibres make up the vagus and what do they innervate?

A

o BE: pharynx, larynx & soft palate (swallowing & phonation)
o GVE: parasympathetic to thoracic and abdominal viscera
o GSA: sensory from upper pharynx and larynx
o GVA: sensory information from lower pharynx and larynx, abdominal and thoracic viscera; stretch receptors aortic arch, chemoreceptors and aortic bodies

35
Q

what are the branches of the vagus in the neck and what do they innervate?

A

• Pharyngeal branches – motor (BE) to pharynx and soft palate
• Superior laryngeal nerve;
o Internal laryngeal – sensory (GSA) to larynx above vocal folds
o External laryngeal – motor to cricothyroid
• Recurrent laryngeal nerve - Motor (BE) to all other intrinsic muscles of larynx and sensory (GVA) to area below vocal folds

36
Q

what are the fibres of the spinal accessory nerve?

A

branchiomotor efferent

37
Q

where does the spinal accessory nerve originate from?

A

from spinal root – originates from spinal roots C1-C5

38
Q

what are the parts of the spinal accessory nerve and what do they innervate?

A

spinal - motor innervation to SCM and trapezius

cranial - joins the vagus

39
Q

how can the spinal accessory nerve be damaged?

A

during a lymph node biopsy

40
Q

how does spinal accessory nerve damage be assessed?

A

weakened shrugging shoulder

asymmetry from behind - one shoulder shows atrophy

41
Q

what are the fibres of the hypoglossal nerve?

A

general somatic efferent – supplies intrinsic & most extrinsic muscles of tongue

42
Q

describe the course of the hypoglossal nerve?

A
  • Rootlets from medulla, exits hypoglossal canal and then to the tongue muscles
  • Joined by C1/C2 spinal nerves which “hitch” a lift to infrahyoid muscles
  • Pass over carotid arteries medial to angle of mandible
43
Q

how can the hypoglossal nerve get injured?

A

during tonsilectomy

44
Q

how does hypoglossal nerve injury present?

A

paralyses ipsilateral half and so tongue deviates towards the side of the lesion (bc of muscle atrophy on that side)

45
Q

what deviation does the uvula show?

A

contralateral deviation (whichever side the uvula goes, the nerve on the other side is affected)

46
Q

explain the sympathetic supply to the head

A

starts in the thorax with the sympathetic chain
structures from the thorax ascend into the head and neck
converge on 2 major cervical ganglia - superior, middle, inferior
then send out post-ganglionic fibres to target organs

47
Q

where are the 3 cervical ganglia found?

A

just inferior to skull base

48
Q

what does the superior cervical ganglia supply?

A

head

49
Q

which structure do the post synaptic sympathetic fibres travel with?

A

internal carotid artery

50
Q

name the ganglion, CN V branch and target of cranial nerve III

A

ganglion - ciliary
branch - opthalmic
target - intrinsic eye muscles

51
Q

name the ganglions, CN V branches and targets of cranial nerve VII

A

ganglion - pterygopalatine
branch - maxillary
target - lacrimal gland, nasal cavity, maxillary sinus, palate

ganglion - submandibular
branch - mandibular
target - submandibular and sublingual glands

52
Q

name the ganglion, CN V branch and target of cranial nerve IX

A

ganglion - otic
branch - mandibular
target - parotid gland