Cranial Nerves: Sensorimotor Flashcards

1
Q

What are the 7 modalities served by the cranial nerves?

A

Motor:
• Somatic efferent
• Special visceral efferent
• General visceral efferent

Sensory:
• Somatic afferent
• Special visceral afferent (smell, taste)
• General visceral afferent
• Special somatic afferent ( sight, hearing, balance)

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2
Q

What are each of the cranial nerves?

A
I - Olfactory 
II - Optic 
III - Occulomotor 
IV- Trochlear 
V- Trigeminal 
VI- Abducent
VII - Facial 
VIII- Vestibulocochlear 
IX- glossopharyngeal 
X- Vagus 
XI - Accessory 
XII - Hypoglossal
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3
Q

Where is the olfactory region?

A

The upper third of the nasal cavity

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4
Q

Describe the route of the olfactory nerve

A
  • Olfactory nerves pass through the cribriform plate (where they are anchored by the dura) and synapse at the olfactory bulb
  • Axons in the olfactory bulb form the olfactory canal
  • Project to the olfactory cortex then to the limbic system, hypothalamus and reticular formation (for visceral and behavioural response to odours)
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5
Q

What type of cells can differentiate into olfactory neurones?

A
  • Basal cells can differentiate into (bipolar) olfactory neurones
  • Can regenerate in humans
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6
Q

What is anosmia and what causes it?

A
  • Olfactory neuropathy cursed by upper respiratory tract infection
  • Trauma, causing the brain and olfactory bulb to move may tear the olfactory nerves
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7
Q

What may happen as a result of a fracture of the cribriform plate?

A
  • CSF rhinnorhea

* Blood stained CSF leaking from the nose

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8
Q

What are the modalities of the divisions of the trigeminal nerve?

A
  • V1 and V2 are afferent only

* V3 is afferent and efferent

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9
Q

What are the roots and nuclei of the trigeminal nerve?

A

Sensory root:
• Mesencephalic nucleus
• Principle (pontine) nucleus
• Spinal nucleus

Motor Root:
• Motor nucleus

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10
Q

Where do the roots of the trigeminal nerve emerge?

A

From the mid pons and run to the trigeminal ganglion

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11
Q

What are the divisions of the trigeminal nerve that emerge from the trigeminal ganglion?

A
  • Ophthalmic (V1)
  • Maxillary (V2)
  • Mandibular (V3)
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12
Q

Describe the course of the ophthalmic nerve

A
  • Runs in the lateral wall of the cavernous sinus
  • Passes through the superior orbital fissure
  • Into the orbit
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13
Q

Describe the route of the Maxillary nerve

A
  • Runs in the lateral wall of the cavernous sinus
  • Passes through foramen rotundum
  • Enters the pterygopalatine fossa
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14
Q

Describe the course of the mandibular nerve

A
  • Passes through foramen ovale

* Infratemporal fossa

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15
Q

Ophthalmic nerve

A

• Sensory only branch
• Picks up sympathetic fibres from the carotid plexus
• Gives off the meningeal branch near the trigeminal ganglion that supplies the dura
• 3 main branches:
- lacrimal
- frontal
- nasociliary

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16
Q

What are the 3 main branches of the ophthalmic nerve?

A
  • Lacrimal
  • Frontal
  • Nasociliary
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17
Q

Function of the lacrimal nerve

A
  • Supplies general sensation to the lacrimal gland, conjunctiva and upper eyelid in the vicinity of the lacrimal gland
  • Carries parasympathetic fibres from the facial nerve (CN VII) to the lacrimal gland
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18
Q

Function of the frontal nerve

A

• Supplies the upper eyelid and conjunctiva, frontal sinus and the scalp as far back as the vertex (afferent)

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19
Q

What are the divisions of the frontal nerve?

A
  • Supra-orbital

* Supra- trochlear nerve

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20
Q

Function of the nasociliary nerve

A
  • Supplies the skin of the medial, upper eyelid and root of the nose
  • Sensation to the cornea of the eye (corneal reflex afferent)
  • Tip of the nose
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21
Q

What are the divisions of the nasociliary nerve?

A
  • Gives off long ciliary nerves and anterior and posterior ethmoidal nerves
  • Continues as the infratrochlear nerve
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22
Q

Branches of the maxillary nerve

A
  • Zygomatic and infra-orbital branches into the orbit via the inferior orbital fissure
  • Palatine and superior alveolar branches to the palate and upper teeth
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23
Q

Describe the route of the infra-orbital nerve

A
  • Enters the orbit via the inferior orbital fissure
  • Exits the orbit via the infra-orbital canal
  • Into the infra-orbital foramen
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24
Q

What is the sensory supply of the maxillary nerve?

A
  • Lateral forehead
  • Zygomatic region
  • Lower lid
  • Side of the nose
  • Cheek (anteriorly)
  • Upper lip
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25
Q

What are the branches of the mandibular nerve?

A
  • Auriculotemporal
  • Buccal
  • Lingual
  • Inferior Alveolar
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26
Q

What is the sensory supply of the maxillary nerve?

A
  • Skin of the auricle and temple
  • Posterior cheek
  • Lower lip and chin
  • General sensation to the anterior 2/3 of the tongue and the floor of the mouth
  • Lower gums and teeth
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27
Q

What is the motor supply of the mandibular nerve?

A
• Muscles of mastication 
- lateral pterygoid 
- medial pterygoid
- masseter 
- temporalis 
• Tensor tympani 
• Tensor veli palatini 
• Mylohyoid 
• Anterior belly of digastric
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28
Q

What reflex tests the mandibular nerve?

A

Jaw jerk

• Tap chin with tendon hammer

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29
Q

What are the modalities of the oculomotor nerve?

A
  • Somatic motor

* visceral motor

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30
Q

Where is the nucleus for the oculomotor nerve?

A

In the midbrain

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31
Q

Describe the course of the oculomotor nerve

A
  • Passes between the posterior cerebral and superior cerebral arteries, before lying close to the posterior communicating artery
  • Runs anteriorly on the lateral Wall of the cavernous sinus
  • Passes through the superior orbital fissure and enters the orbit
  • In the orbit it divides into superior and inferior divisions (rami) through the tendinous ring of zinn
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32
Q

What may happen as a result of an aneurysm of the posterior communicating artery?

A

May compress the oculomotor nerve

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33
Q

Superior branch of the oculomotor nerve

A

• Oculomotor fibres and sympathetics from the superior cervical ganglion

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34
Q

Where is the nucleus of the trochlear nerve?

A

In the midbrain

35
Q

Describe the course of the trochlear nerve

A
  • Nerves exit the brainstem from its posterior surface
  • Runs anteriorly around the cerebral peduncle and enters the cavernous sinus
  • Passes through the superior orbital fissure
  • Supplies the superior oblique muscles
36
Q

What does injury of the trochlear nerve result in?

A
  • Patient not able to look medially and inferiorly

* Patient experiences diplopia (Blurred and double vision) while walking down stairs or reading a book

37
Q

What are the modalities of the abducent nerve?

A

• Motor only

38
Q

Where is the nucleus of the abducent nerve?

A

In the pons

39
Q

Describe the course of the abducent nerve

A
  • Exits the brainstem medially between the pons and medulla
  • Enters the cavernous sinus (through not it wall)
  • Enters the orbit through the superior orbital fissure
  • Supplies the lateral rectus
40
Q

What would injury of the abducent nerve result in?

A
  • Diplopia when looking right

* eye won’t fully abduct

41
Q

Where is the nucleus of the facial nerve?

A

In the pons

42
Q

What are the nuclei of the facial nerve?

A
  • Motor nucleus

* Nucleus solitarius

43
Q

Motor nucleus of the facial nerve

A
  • Superior and inferior divisons
  • Superior innervates the upper facial muscles
  • Inferior innervates lower muscles
  • Superior divison is connected to ipsilateral and contralateral motor cortices
  • Inferior division is connected to the contralateral cortex only
44
Q

Where does the Motor root of the facial nerve emerge?

A

In the angle between the lower pons and the cerebellum - the cerebellopontine angle

45
Q

Describe the course of the facial nerve

A
  • Emerges from cerebelloponitne angle
  • Enters the temporal bone at the internal acoustic meatus with CNVIII and the labyrinthine artery
  • Enters the facial canal within the temporal bone
  • Cell bodies for taste fibres in geniculate ganglion
  • Chordates tympani
  • Exits the temporal bone through stylomastoid foramen
  • Sends branches to supply occipitals and auricular muscles
  • Enters the parotid gland and divides to form a plexus within it
46
Q

Birth and facial nerve complication

A
  • At birth, the mastoid process is not properly developed

* Facial nerve is at risk of compression during delivery with forceps leading to the paralysis of the facial muscles

47
Q

What are the branches of the facial nerve?

A
  • Temporal
  • Zygomatic
  • Buccal
  • Marginal mandibular
  • Cervical
48
Q

What does the temporal nerve supply?

A
  • Frontal belly of occipitofrontalis

* orbicularis oculi

49
Q

What does the zygomatic nerve supply?

A

• Part of the orbiculares oculi

50
Q

What does the buccal nerve supply?

A
  • Buccinator

* Lip muscles

51
Q

What does the marginal mandibular supply?

A

• Muscles of the lower lip and chin

52
Q

What does the cervical nerve supply?

A

Platysma

53
Q

Facial nerve injury at the cerebellopontine angle

A
  • Balance and hearing problems
  • Ipsilateral facial muscle paralysis
  • Hyperacusis (pain on loud sounds)
  • Taste disturbances
  • Reduced lacrimal secretion
54
Q

Facial nerve injury distal to the stylomastoid foramen

A
  • Ipsilateral facial muscle paralysis

* Dry eye, drooling

55
Q

Facial nerve injury within the petrous temporal bone

A
  • Depending on exact location:
  • Reduced lacrimal secretion
  • Hyperacusis
  • Taste disturbance
  • Ipsilateral facial paralysis
56
Q

Corneal reflex

A
  • eyes close in response to touch
  • Efferent branch is facial nerve
  • Efferent branch is nasociliary of trigeminal
57
Q

Where is the nuclei of the glossopharyngeal nerve?

A

In the medulla

58
Q

What is the motor nucleus of the glossopharyngeal nerve?

A

Nucleus ambiguus

59
Q

What is the sensory nucleus of the glossopharyngeal nerve?

A

Nucleus solitarius

60
Q

Branches of the glossopharyngeal nerve

A

• Tympanic branch to the middle ear, tympanic membrane and mastoid air cells

61
Q

Glossopharyngeal sensory

A
  • General sensation from the middle ear, oropharynx, palatine tonsil, inferior aspect of soft palate, posterior 1/3 of the tongue
  • General visceral sensation from the carotid sinus and carotid body
  • Special visceral sensation (taste) from posterior 1/3 of the tongue
62
Q

Motor supply glossopharyngeal

A

• Stylopharyngeal

63
Q

Where are the nuclei of the vagus?

A

medulla

64
Q

Motor nucleus of the vagus

A

• Nucleus Ambiguus

65
Q

Sensory nucleus of the vagus

A

• Nucleus solitarius (taste and general visceral)

66
Q

Describe the course of the vagus

A

• Leaves the brainstem and passes through the jugular foramen with CNIX and XI

67
Q

General somatic sensation vagus

A
  • Deep Auricle

* Parts of the external acoustic meatus

68
Q

General visceral sensation vagus

A
  • Laryngopharynx

* Larynx

69
Q

Motor supply vagus

A

• Striated muscle of larynx and pharynx

70
Q

Gag reflex

A
  • Touch the posterior wall of the pharynx or the root of the tongue and the pharyngeal muscles supplied by the vagus will contract
  • Afferent = glossopharyngeal
  • Efferent = vagus
71
Q

What is the modality of the accessory nerve

A

Motor only

72
Q

Roots of the accessory Neve

A
  • Spinal roots from C1 to C5
  • Cranial root from nucleus ambiguus
  • Spinal roots enter the cranial cavity through the foramen magnum and join with the cranial root
  • both roots exit the skull via the jugular foramen as accessory nerve
73
Q

Course of the accessory nerve

A
  • Exits the skull via jugular foramen

* Crosses the posterior triangle in the investing layer of fascia, surrounded by lymph nodes

74
Q

What does the accessory nerve innervate

A
  • Trapezius

* Sternocleidomastoid

75
Q

Modalities of the hypoglossal nerve

A

Motor only

76
Q

Where is the hypoglsosal nucleus?

A

Medulla

77
Q

Describe the course of the hypoglossal

A
  • Exits brainstem anterior to the olive
  • Emerges from the hypoglossal (anterior condylar canal)
  • Descends in the neck, passing lateral to both the internal and external carotid arteries (associated with a loop of Cx nerves that supply a strap of muscles of the neck)
  • Enters the oral cavity under the tongue, between the mylohyoid and hypoglossus
78
Q

What does the hypoglossal nerve supply?

A

All muscles of the tongue except palatoglossus

79
Q

What does injury of the hypoglossal nerve cause?

A
  • Ipsilateral tongue weakness

* Tongue deviates to the side of weakness

80
Q

Innervation, posterior 1/3 of the tongue

A
  • Taste by glossopharyngeal
  • General sensation by glossopharyngeal
  • Motor by hypoglossal except palatoglossus (vagus)
81
Q

Innervation, anterior 2/3 of the tongue

A
  • Taste by chordates tympani or nervous intermedium (facial)
  • General sensation by the lingual nerve of V3
  • Motor by hypoglossal except palatoglossus (vagus)
82
Q

Sensory innervation of the oropharynx, palatine tonsil, inferior aspect of soft palate, posterior 1/3 of tongue

A

Glossopharyngeal

83
Q

Sensory innervation of laryngopharynx, vallecula and epiglottis

A

Vagus

84
Q

Sensory innervation of the nasopharynx

A

Maxillary