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Head and Neck > Lecture 9 - CN VI - XII > Flashcards

Lecture 9 - CN VI - XII Flashcards

1
Q

4 cranial nerves that come from the pons

A

CN V - trigeminal
CN VI - abducens
CN VII - facial
CN VIII - vestibulocochlear

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2
Q

Route of the abducens nerve

A
  1. Pontomedullary junction
  2. Through the middle of the cavernous sinus
  3. Through the superior orbital fissure
  4. Through the orbit to the lateral rectus muscle
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3
Q

Role of the abducens nerve

A

Abduction of the eye

Suppiles motor innervation to the lateral rectus muscle

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4
Q

CN VI test

A

Test eye movements

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5
Q

CN VI lesion presentation

A

Diplopia

Cannot abduct affected eye

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6
Q

What causes injury to the CN VI

A

Microvascular complications:

  • diabetes
  • hypertension

Increased intracranial pressure

  • tumour
  • haemorrhage
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7
Q

CN VII role

A

Special sensory - taste to anterior 2/3rds of the tongue

Motor - Muscles of facial expression and nerve to stapedius

Autonomic - Parasympathetics to the :

  • Submandibular and sublingual salivary glands
  • Lacrimal glands
  • Mucosal glands in nose

General sensory - small area of the external ear

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8
Q

What does the stapedius do?

A

Tampers the vibrations made by ossicles due to sound therefore controlling volume tolerance

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9
Q

Roots of the facial nerve

A

2 roots at the cerebellopontine angle:

  • Motor root - larger
  • Nervus intermedius - sensory and parasympathetic
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10
Q

Route of the facial nerve

A
  1. Ponto medullary junction
  2. The motor root and nervus intermedius converge and run through the internal acoustic meatus
  3. The facial nerve goes through the petrous bone, forms the geniculate ganglion and exits the petrous bone
  4. Splits into:
    - Greater petrosal nerve
    - Chorda tympani nerve
    - Stapedius nerve
  5. Exits the stylomastoid foramen
  6. Runs through the parotid gland to supply the muscles of facial expression
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11
Q

How will a lesion of the facial nerve at the internal acoustic meatus present?

A

All branches affected:

  • Dry eyes
  • Dry mouth
  • Taste altered
  • Increased sensitivity to loud noises - hyperacusis
  • Bell’s palsy
  • Loss of general sensation around ear
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12
Q

How will a lesion of the facial nerve at the stylomastoid foramen present?

A

All branches have been given off:

  • Bells palsy
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13
Q

CN VII test

A

Change in taste
Test muscles of facial expression
Corneal reflex - Obicularis oculi orbital and palpebral aspect

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14
Q

What can cause CN VII damage?

A

Middle ear pathologies - close relationship to the vestibulocochlear nerve within the posterior cranial fossa as both enter the internal acoustic meatus

Tumour of the parotid gland - enlargement causes facial nerve compression

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15
Q

Corneal reflex

A

Afferent limb - Va

Efferent limb - CN VII

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16
Q

Route of the vestibulocochlear nerve

A
  1. The cochlear nerve and vesitibular nerve from the cochlea and the semicircular canals form the vestibulocochlear nerve
  2. Enter the internal acoustic meatus
  3. To the pontomedullary junction
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17
Q

CN VIII role

A

Balance

Hearing

18
Q

CN VIII test

A

Hearing test

Vertigo - ask about balance

19
Q

Presbyacusis

A

Age related hearing loss

20
Q

Acoustic neuroma

and presentation

A

Benign tumour of the schwann cells surrounding the vestibulocochlear nerve

Growth compresses the nerve

Presentation:
Unilateral hearing loss 
Tinnitus
Vertigo
Numbness, pain or weakness down one half of face
21
Q

Which nerves exit the jugular foramen?

A

CN XI - Glossopharngeal nerve
CN X - Vagus
CN XI - Spinal accessory

22
Q

Role of CN IX

A

Special sensory - Taste to posterior 1/3rd of tongue

General sensory - 
Posterior 1/3rd tongue
Oropharynx
Palatine tonsils
Middle ear and tympanic membrane via tympanic branch
Carotid body and sinus

Autonomic - Parasympathetics to the parotid gland

Motor - Supplies the stylopharyngeus

23
Q

Why do patients complain of ear pain when they have a sore throat?

A

The glossopharyngeal nerve supplies the oropharnx and middle ear

Therefore can get referred pain from the palatine tonsils to ear even if the ear is normal

24
Q

CN IX test

A

Tested alongside vagus nerve

Ask patient to swallow
Gag reflex
Taste - not formally tested

25
Q

Gag reflex

A

Afferent- CN IX

Efferent - CN X and CN IX

26
Q

Route of CN IX

A
  1. Medulla
  2. Jugular foramen
  3. Carotid sheath
  4. Exits carotid sheath early and gives off the tympanic branch which suplies the inner ear
  5. Continues to tongue, oropharnx and parotid gland
27
Q

Route of CN X

A
  1. Medulla
  2. Jugular foramen
  3. Carotid sheath
  4. Through neck into the thorax and abdomen
28
Q

Role of CN X

A

General sensory:
Lower pharynx
All of larynx
Small part of external ear and tympanic membrane

Motor -
Soft palate muscles
Pharyngeal muscles except stylopharyngeus
Laryngeal muscles

Autonomic - parasympathetic to thoracic and abdominal viscera

  • heart - decrease BP
  • tracheobronchial tree - bronchodilation
29
Q

Branches of vagus nerve

A

Left and right recurrent laryngeal nerve

30
Q

What do the recurrent laryngeal nerves turn under?

A

Left recurrent laryngeal nerve - aortic arch

Right recurrent laryngeal nerve - right subclavian artery

31
Q

What muscles does the vagus nerve supply?

A

Laryngeal - Intrinsic muscles of the vocal cords
Cricothyroid

Pharyngeal -
Palatopharyngeus (hard palate)
Salpingopharyngeus
Superior, middle and inferior pharyngeal constrictors

Soft palate: Palatoglossus

32
Q

CN X test

A

Changes in:

  • speech - hoarseness of voice and dysphonia
  • cough
  • ability to swallow
  • Gag reflex
  • Movement of soft palate and uvula when saying ‘aah’
33
Q

CN XI role

A

Motor innervation to:
Trapezius - shrug shoulders
SCM - lateral flexion of head and rotation

34
Q

Route of CN XI

A
  1. Medulla
  2. Jugular foramen
  3. Carotid sheath and exits early
  4. Deep to SCM
  5. Passes posterolaterally across the posterior triangle
  6. Enters the trapezius
35
Q

Lesion of the CN XI in the posterior triangle

A

Only the trapezius will be affected as the nerve has already supplied the SCM

36
Q

CN XI test

A

Shrug shoulder against resistance

Turn head against resistance

37
Q

How can CN XI be damaged?

A

Damage to the posterior triangle in e.g:

  • lymph node biopsies
  • surgery
  • Stab wound
38
Q

Role of CN XII

A

Motor innervation to the muscles of the tongue except the palatoglossus

39
Q

What muscles does the CN XII innervate?

A

Genioglossus
Hypoglossus
Styloglossus

40
Q

Route of CN XII

A
  1. Medulla
  2. Hypoglossal canal
  3. Runs medial to the angle of the mandible and crosses the ICA and ECA in neck
41
Q

CN XII test

A

Weakness and atrophy of tongue on the ipsilateral side

Deviates to the side of weakness

42
Q

What can damage the hypoglossal nerve?

A

Surgery to the jaw and upper carotid sheath

Head and Neck (15 decks)

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