Lec 8 - Cranial nerves VII - XII Flashcards

1
Q

What is cranial nerve VII?

A

Facial nerve

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2
Q

What is the pathway of the facial nerve (CN VII)?

A
  1. Lower puns (junction between pons and medulla)
  2. This enters the pertrous part of the temporal bone via the internal acoustic meatus.
  3. There are three branches within the petrous bone.
  4. Then exits through the base of the skull which is the stylomastoid foramen.
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3
Q

What are the branches within the petrous bone?

A
  1. greater petrosal nerve
  2. chorda tympani nerve
  3. nerve to stepedius
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4
Q

What is the stylomastoid foramen?

A

It is the hole between the mastoid process and the styloid process.

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5
Q

what are the special sensory functions of the facial nerve?

A
  • anterior 2/3 of tongue for taste.
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6
Q

what are the autonomic (parasympathetic) functions of the facial nerve?

A
  • lacrimal glands (tears)
  • mucosal glands in the nose and roof of mouth
  • salivary glands all except the parotid gland.
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7
Q

What are the motor functions of the facial nerve?

A

for muscles of facial expression.

  • fibres from facial nerve to supply muscles of facial expression are outside.
  • The stapedious muscle is innervated by motor
  • —-> It dampens down excessive vibration at the oral window.
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8
Q

What are the general sensory functions of the facial nerve?

A

Small area of the external ear.

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9
Q

What are the bits of the facial nerve we see as it comes out the brainstem?

A
  • CN VIII
  • CN VII
  • Nervus intermedius portion of CNVII
  • Geniculate ganglion
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10
Q

What are the nucleus solitaires rostral gustatory portion (special sensory)?

A

These are nerves carrying special sense taste.

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11
Q

What is the motor nucleus of CN VII (branchial motor)?

A

These are nerves carrying motor to muscles of facial expression.

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12
Q

What is the superior salivary nucleus (parasympathetic motor)?

A

These are autonomic fibres to the glands including salivary, lacrimal, mucosal In nose and palate.

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13
Q

What is the pontine trigeminal nucleus (general sensory)?

A

This is a small area of sensory innervation within the ear.

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14
Q

What are the two roots of the facial nerve at the cerebellopontine angle?

A
  1. motor root (larger, just motor axons).

2. Nervus intermedius ( sensory and parasympathetic axons)

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15
Q

How do you clinical test the facial nerve

A
  • by testing the muscles of facial expression and the corneal reflex.
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16
Q

What are some of the symptoms of facial nerve damage?

A
  • hyperacusis
  • –> This is sensitivity to loud noises.
  • ————> This tells us that there is a problem to the nerve of the stapedius, so can’t act to dampen the vibrations.
  • middle ear pathology in the petrous bone can sometimes involve the facial nerve.
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17
Q

What has a close relationship with the vestibulocochlear nerve?

A

There is a close relationship with vestibulocochlear never within the posterior cranial fossa and both enter internal acoustic meatus.

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18
Q

What do the extra cranial branches of the facial nerve have a close relationship with?

A

Extracranial branches of facial nerve have close relationship with parotid gland.

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19
Q

What does the corneal reflex do?

A
  • Cotton wool has to reach the cornea

- The ophthalmic division of the trigeminal nerve (sensory) and facial nerve (motor) will detect this.

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20
Q

What controls the afferent limb of the corneal reflex?

A

The ophthalmic division of the trigeminal nerve

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21
Q

What controls the efferent limb of the corneal reflex?

A

The facial nerve

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22
Q

What can you not do in facial nerve palsy such as Bell’s palsy?

A

You won’t be able to close your eye.

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23
Q

What is CN VIII?

A

Vestibulocochlear

- This is purely sensory.

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24
Q

What two places can the vestibulocochlear nerve arise from?

A
  • cochlea

- semicircular canals (vestibular system)

25
Q

What is the pathway of the vestibulocochlear nerve?

A
  1. vestibulocochlear nerve
  2. internal acoustic meatus
  3. Lower pons (junction between pons and medulla)
26
Q

What is the special sensory function of the vestibulocochlear nerve?

A

hearing and balance

27
Q

What is the clinical testing for the vestibulocochlear nerve?

A

Testing hearing and enquiring about balance.

28
Q

What can cause hearing loss - sensorineural?

A

damage involving cochlea, cochlear component of vestibulochlear nerve or brainstem nucleus.

29
Q

What is presbyacusis?

A

Old-age related hearing loss.

30
Q

What causes disturbance of balance (vertigo)?

A

pathology involving semicircular canals, vestibular component of vestibulocochlear nerve or brain nucleus.

31
Q

What is acoustic neuroma?

A

This is a benign tumour involving vestibulocochlear nerve.

  • They are benign tumours of the schwann cells surrounding (the vestibular component of ) CN VIII.
  • Their physical presence causes compression of the whole nerve +/- CNs in close proximity.
32
Q

What are the signs and symptoms of an acoustic neuroma?

A
  • unilateral hearing loss
  • tinnitus
  • vertigo
  • numbness, pain or weakness down one half of face.
33
Q

What are the 4 cranial nerves that arise from the medulla?

A
  • CN XI, CN XII, CN X and CN IX.
  • these 4 cranial nerves arise from the medulla and exit the base of the skull to enter into the superior part of the carotid sheath.
  • only the cranial nerve X runs the length of the carotid sheath.
34
Q

What is cranial nerve CN IX?

A

Glossopharyngeal nerve

35
Q

What is the main function of the glossopharyngeal nerve?

A
  • The sensory supply of the oropharynx, posterior 1/3 of the tongue and the middle ear.
36
Q

What is the general sensation function of the glossopharyngeal nerve?

A
  1. palatine tonsils and oropharynx.
  2. middle ear and tympanic membrane
  3. sensory from the carotid body and sinus.
37
Q

What is the special sensory function of the glossopharyngeal nerve?

A

taste and general sensation in the posterior 1/3 of the tongue.

38
Q

What is the autonomic function of the glossopharyngeal nerve?

A

carries parasympathetic innervation to the parotid gland.

39
Q

What is the motor function of the glossopharyngeal nerve?

A

supplies one muscle - the stylophayngeus which assists in swallowing.

40
Q

What is the clinical testing of the glossopharyngeal nerve?

A
  1. Gag reflex (sensory limb)
    - This is only tested if concerns around swallowing and integrity of nerves involved in this reflex.
  2. taste is not formally tested.
  3. It is tested in conjunction with vagus nerve CN X.
41
Q

What is CN X?

A

Vagus nerve

42
Q

What is the pathway of the vagus nerve?

A
  1. Medulla
  2. Jugular foramen
  3. Carotid sheath
  4. Through neck, into the thorax and abdomen.
43
Q

What are the general sensory function of the vagus nerve?

A
  • sensory to lower pharynx and larynx.

- sensory to posterior part of the external ear and tympanic membrane.

44
Q

What are the motor functions of the vagus nerve?

A

`muscles of the soft palate, pharynx and larynx.

45
Q

What are the autonomic functions of the vagus nerve?

A

parasympathetic to thoracic such as heart, tracheobranchial tree and abdominal viscera.

46
Q

In summary what does the vagus nerve do?

A
  • It is a mixed motor and sensory nerve.

- It innervates the structures of the neck, thorax and abdomen.

47
Q

Where does the right vagus nerve run?

A

right vagus nerve runs in the carotid sheath.

48
Q

Where does the left vagus nerve run?

A

left vagus nerve runs in the carotid sheath.

49
Q

Where does the left recurrent laryngeal nerve turn?

A

left recurrent laryngeal nerve turns under the arch of the aorta.

50
Q

Where does the right recurrent laryngeal nerve turn?

A

right recurrent laryngeal nerve turns under the right subclavian.

  • it comes off the vagus nerve and loops under the blood vessel.
  • It carries motor fibres to the laryngeal muscles allowing you to speak.
51
Q

Describe the pathway of the spinal accessory nerve

A
  1. emerges through the jugular foramen.
  2. Then passes deep to the SCM and provides its motor innervation.
  3. Runs posterolaterally across the posterior triangle.
  4. Enters deep to the trapezius and provides it motor innervation.
52
Q

How do you test the spinal accessory nerve?

A
  1. Shrug shoulders against resistance ( trapezius)

2. Turn head against resistance (sternocleidomastoid)

53
Q

What is the clinical relevance of shrugging shoulders against resistance to test CN XI?

A

The spinal accessory runs inferiorly through the neck in the posterior triangle. - quite superficial.

54
Q

What is the clinical relevance of turning head against resistance to test Cn XI?

A

The spinal accessory nerve is susceptible to injury in this area e.g. in lymph node biopsies, surgery and stab wound.

55
Q

What is the motor function of the Hypoglossal nerve?

A

Muscles of the tongue all except one.

56
Q

What is the location of CN XII?

A
  • It runs medial to the angle of the mandible.

- It crosses internal and external carotid arteries in the neck.

57
Q

What does the hypoglossal nerve pass through?

A

The hypoglossal canal

58
Q

How is the function of CN XII tested?

A
  • Inspection and movement of the tongue.

- –> This is because damage to CN XII causes weakness and atrophy of the tongue muscles on the ipsilateral side.