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Head and Neck > Lecture 8 - CN I - V > Flashcards

Lecture 8 - CN I - V Flashcards

1
Q

Which 2 cranial nerves arise from the forebrain ?

A

CN I - Olfactory

CN II - Optic

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2
Q

Purely special sensory cranial nerves

A

CN I- Olfactory
CN II - Optic
CN VIII - Vestibulocochlear

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3
Q

Motor cervical nerves

A 
CN III - Occulomotor 
CN IV - Trochlear 
CN VI - Abducens
CN XI - Spinal accessory
CN XII - Hypoglossal
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4
Q

Cervical nerves that carry autonomics

A

CN III - occulomotor
CN VII - facial nerve
CN IX - glossopharyngeal
CN X - vagus

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5
Q

Brain stem

A

Joins the brain to the spinal cord

Regulates cardio- resp function and maintains consciousness

Contains ascending sensory fibres and descending motor fibres

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6
Q

What makes up the brainstem?

A

Midbrain
Pons
Medulla

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7
Q

Course of the olfactory nerve

A
  1. Olfactory nerve in the roof of the nasal canal
  2. Enters the cribriform plate of the ethmoid bone
  3. Olfactory bulbs to olfactory tracts
  4. To temporal lobe
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8
Q

Function of the olfactory nerve

A

Olfaction (smell)

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9
Q

CN I test

A

Change in sense of smell

Anosmia - loss of sense of smell

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10
Q

Commonest cause of anosmia

A

URTI (cold)

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11
Q

Causes of anosmia

A

URTI
Head injury - basilar skull fracture
Tumour at base of frontal lobe

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12
Q

Route of the optic nerve

A
  1. Retinal ganglion cells at the optic disc have axons that converge into the optic nerve
  2. Enters the optic canal
  3. Fibres cross at the optic chiasm
  4. Optic tracts enter the primary visual cortex in the occipital lobe
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13
Q

Sight when there is a lesion in 1 optic nerve?

A

Only the ipsilateral eye sight is affected

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14
Q

Sight when there is a lesion in the optic chiasm

A

Sight in both eyes are affected

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15
Q

What can pituitary tumours course?

A

Compression on the optic chiasm

  • Bitemporal hemianopia
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16
Q

CN II tests

A

Visual acuity test - Snellen test
Visual field test
Pupillary light response
Optic disc visualised by a opthalmoscope

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17
Q

CN II function

A

Sight

Afferents of the pupillary light response

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18
Q

Papillodema

A

Swollen optic disc

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19
Q

Photophobia

A

The optic nerve carries extensions of the meninges

Raised intracranial pressure can cause disruption to the nerve causing photophobia - trait of meningism

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20
Q

Communication of the optic nerve with the midbrain

A

Communication from the optic tract with the brainstem midbrain to allow the pupillary reflex to light

  • Occulomotor nerve is stimulated to constrict the pupil
21
Q

Route of the occulomotor nerve

A
  1. Midbrain
  2. Lateral wall of the cavernous sinus
  3. Superior orbital fissure
  4. To the extra-ocular muscles except the superior oblique and lateral rectus muscles, levator palbebrae superioris
22
Q

Muscles that CN III control

A

Superior rectus
Inferior rectus
Medial rectus
Inferior oblique

Levator palpebrae superioris

Parasympathetic innervation to the sphincter pupillae muscle

23
Q

CN III role

A

Eye movements
Raise eyelids
Constrict the pupil

Efferent limb of the pupillary light response

24
Q

Why is the occulomotor nerve vulnerable to compression

A

During raised intracranial pressure, the uncus can herniate and compress the nerve.

Between the tentorium cerebelli and uncus

25
Q

What can happen in CN III external compression

A

Pupil dilation as the parasympathetic fibres are on the periphery of the nerve that innervate the sphincter pupillae

26
Q

CNIII tests

A

Eye movements - follow finger
Inspect eyelids and pupil size
Pupillary light reflex

27
Q

Presentation of CNIII lesion

A

Eye in down and out position
Pupil dilation
Complete ptosis
Diplopia

28
Q

Causes of CN III injury

A 
External compression:
Raised intracranial pressure:
-tumour 
-haemorrhage
Aneurysm 
Cavernous sinus thrombosis

Internal compression:
Vascular secondary to:
- diabetes
- hypertension

(pupil sparring)

29
Q

Route of the trochlear nerve

A
  1. Mid brain
  2. Through the lateral wall of the cavernous sinus
  3. Through the superior orbital fissure
  4. To the superior oblique extraocular muscle
30
Q

Role of CN IV

A

Eye movement - superior oblique muscle

31
Q

CN IV test

A

Eye movement test - follow finger

32
Q

Why is the trochlear nerve most susceptible to damage

A

Arises from the dorsal aspect of the brain stem and hooks around therefore has a long intracranial course

33
Q

Presentation of CN IV lesion

A

Up and in eye position

Diplopia

34
Q

3 branches of the trigeminal nerve

A

Opthalmic
Maxillary
Mandibular

35
Q

Role of the trigeminal nerve

A 
General sensation to the:
- face 
- part of scalp 
- paranasal air sinuses
- nasal cavity 
- oral cavity 
- anterior 2/3rds of tongue
meninges

Motor innervation to the muscles of mastication

36
Q

Opthalmic general sensory structures

A

Forehead
Upper eyelid
Medial nose

37
Q

Maxillary general sensory structures

A

Cheek
Lower eye lid
Lateral nose

38
Q

Mandibular general sensory structures

A

Lower lip
Jaw and chin
Lateral head and ear

39
Q

Route of Va

A
  1. Pons
  2. Trigeminal ganglion
  3. Va through the superior orbital fissure
  4. To orbit
40
Q

Route of Vb

A
  1. Pons
  2. Trigeminal ganglion
  3. Vb through foramen rotundum
  4. To the pterygopalatine fossa
41
Q

Route of Vc

A
  1. Pons
  2. Trigeminal ganglion
  3. Vc through the foramen ovale
  4. To the infratemporal fossa
42
Q

Which branch of the trigeminal nerve supplies motor innervation to the muscles of mastication?

A

Vc - Mandibular

43
Q

CN V test

A

Sensation in dermatomal areas of Va, b and c

Check the function of the muscles of mastication

Check the corneal reflex - blinking (afferent limb)

44
Q

Conditions involving the trigeminal nerve

A

Trigeminal neuralgia

Shingles - sight threatening with vesicle scars

Orbital/facial trauma - can affect the inferior orbital and superior alveolar nerve

45
Q

Branches of the opthalmic nerve

A 
Frontal nerve:
- Supraorbital 
- Supratrochlear 
Lacrimal nerve
Nasociliary
46
Q

Branches of the maxillary nerve

A

Infraorbital nerve - cheek and lower eyelid

Superior alveolar nerve - upper lip, teeth and gums

(nerve blocker used by dentists)

47
Q

Branches of the mandibular nerve

A

Inferior alveolar nerve - Lower lip, teeth and gums
(continues as the mental nerve)
- Auricotemporal - ear, temples and TMJ
- Lingual - anterior 2/3rds of the tongue

48
Q

Which nerve is susceptible to damage in a mandibular fracture

A

Inferior alveolar nerve

Head and Neck (15 decks)

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