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Neuro > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

Describe the pathway and components of CN I [3]

Type of nerve fiber [1]

A
  • Olfactory Nerve
  • Purely Special Sensory (smell)

Fibres start in receptors in the olfactory epithelium of the nasal cavity [1]

  • -> Pass through foramina in the cribriform plate of the ethmoid [1]
  • -> Enters the olfactory bulb and goes to primary olfactory area in temporal lobe [1]
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2
Q

Whats the clinical relevance of the 1st cranial nerve? [2]

A

If you fracture the cribriform plate [1] you can tear the olfactory nerve fibres causing anosmia [1]

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3
Q

Describe the pathway and components of the 2nd cranial nerve [6]
Type of nerve fiber [1]

A
  • Optic Nerve
  • Purely Special Sensory (Vision)
  • Retinal Nerve Fibres
  • > Optic Disc -> Optic Nerve (in optic canal)
  • > Fibres mix at the optic chiasm and nasal fibres swap sides. So temporal fibres and contralateral nasal fibres of each side form optic tracts
  • > Synapse at LGB
  • > Form Right and Left Optic Radiations
  • > Feed into the left and right Primary Visual Cortex
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4
Q

Whats the clinical relevance of Cr N II [2]

A

Papilloedema (Optic Disc Swelling
- Due to increased Intracranial Pressure

Transection of various points along the visual pathway can lead to different patterns of blindness

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5
Q

What could cause damage to the optic chiasm? [1]

A

Pressure from a Pituitary Tumour

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6
Q

What are the components of the 3rd cranial nerve? [2]

A

Oculomotor:

  • Somatic Motor supply to most of the extraocular muscles
  • Autonomic Motor (parasympathetic) to the constrictor pupillae and the ciliaris muscle
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7
Q

What extraocular muscles arnt supplied by the oculomotor nerve? [2]

A
  • Sup Oblique (Cranial Nerve IV - Trochlear)

- Lateral Rectus (Cranial Nerve VI - Abducens)

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8
Q

Whats the pathway of the 3rd cranial nerve through the skull [2]

A
  • Arises from midbrain- pontine junction

- Emerges throught he superior orbital fissure

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9
Q

Whats the clinical relevance of the oculomotor nerve? [4]

A

Ptosis
- Loss of somatic innervation to the levator palpebrae Superioris

Eyeball Abducted & Depressed:
- Due to loss of innervation to the extraocular muscles so the sup oblique depresses it and the lateral rectus abducts it

Loss of pupillary reflex
- Loss of autonomic motor innervation

No lens accommodation
- Loss of autonomic motor innervation

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10
Q

What are the components of the 4th cranial nerve? Type of nerve fibre [1]

A

Its Purely Somatic Motor to the superior oblique

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11
Q

Describe the pathway of the 4th cranial nerve through the skull? [2]

A

Comes from the midbrain and emerges through the superior orbital fissure

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12
Q

Clinical relevance of the trochlear nerve? [4]

A

Lose innervation to the sup oblique [1] so when you look down [1] one eye doesnt depress properly [1] leading to diplopia [1]

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13
Q

Describe the pathway of the 5th cranial nerve [6]

A

Emerges from pons [1] and forms the trigeminal ganglion [1], then it divides into the 3 branches [1]

  • Ophthalmic exits via Sup Orbital Fissure
  • Maxillary exits through Foramen Rotundum
  • Mandibular Exits through the Foramen Ovale
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14
Q

Whats the components of the trigeminal nerve branches? [4]

Describe the type of nerve fibre for each component

A

Ophthalmic V1
- General Sensory to cornea/eyelid/scalp/nose/nasal&sinus mucosa

Maxillary V2
- General Sensory to face, upper teeth, TM joint, palate and nose

Mandibular V3
- General Sensory to face, lower teeth, TM joint, mouth mucosa & ant 2/3rds of tongue

  • Somatic Motor to muscles of mastication, digastric, tensor veli palatine & Tensor Tympani
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15
Q

Whats the clinical relevance of the trigeminal nerve? [4]

A
  • Paralysed Muscles of mastication
  • Loss of corneal or sneezing reflex
  • Loss of facial sensation
  • Trigeminal Neuralgia
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16
Q

Describe the pathway [2] components [1] and clinical relevance of the 6th cranial nerve [2]
Components: What type of nerve fibre is it made of?

A
  • Abducens
  • Emerges from between pons & Medulla then out via the Sup Orbital Fissure
  • Components: Contains purely somatic motor nerves to the lateral rectus
  • Loss of this nerve leads to medial deviation [1] of the eye and diplopia [1]
17
Q

What are the components of the facial nerve CN7? [4]

A

Somatic Motor
- Muscles of facial expression, stapedius & Digastric

Autonomic Motor

  • Salivary Glands (not parotid)
  • Lacrimal glands
  • Other glands in the nose/palate

Special Sensory:
- Taste to Ant 2/3rds of tongue

General Sensory
- External Acoustic Meatus

18
Q

Whats the pathway of the facial nerve? [4]

A

Emerges from between Pons & Medulla [1]

Then exits via the internal acoustic meatus [1] through the facial canal [1] and out stylomastoid foramen [1]

19
Q

Whats the clinical relevance of Cranial Nerve VII [1]

A
  • Damage leads to facial palsies

E.g. Bell’s Palsy where you cant frown, close your eyelid or bare teeth on one side

20
Q

Whats the pathway of the 8th cranial nerve? [3]

A

Vestibulocochlear nerve
Emerges from between Pons and Medulla [1]
Exits through internal acoustic meatus [1]
Divides into Vestibular and Cochlear nerves in the middle ear [1]

21
Q

What are the components of the vestibulocochlear nerve? [1]

A

Special Sensory

22
Q

Clinical relavance of the 8th cranial nerve? [4]

A
  • Tinnitus
  • Sensorineural deafness
  • Vertigo
  • Nystagmus
23
Q

Describe the pathway of the glossopharyngeal nerve? [2]

A

Emerges from the medulla

Exits via the jugular foramen

24
Q

What are the components of the 9th cranial nerve? [5]

A
  • Special Sensory to post 3rd of the tongue
  • General Sensory to the middle ear and post oral cavity/post 3rd of tongue
  • Visceral Sensory to carotid body/sinus
  • Autonomic motor to the parotid gland
  • Somatic Motor to the Stylopharyngeus (swallowing)
25
Q

Clinical application of cranial nerve 9? [2]

A
  • Loss of gag reflex & taste from back of tongue

- Associated with X & XI injuries (Jugular Foramen Syndrome)

26
Q

Pathway of the 10th cranial nerve? [2]

A

Vagus exits the medulla and passes through the jugular foramen

27
Q

Components of the Vagus Nerve? [5]

A

Special Sensory (Taste) to epiglottis and palate
General Sensory to auricle and EAM
Visceral Sensory to pharynx and below
Autonomic motor to bronchi, gut and heart
Somatic Motor to swallowing muscles and speaking muscles. (pharynx, larynx & Oesophagus)

28
Q

Clinical relevance of Cr N X? [3]

A
  • Difficulty swallowing if you damage the pharyngeal branches
  • Difficulty speaking/hoarseness if you damage the laryngeal branches
  • Jugular Foramen Syndrome (Damage to IX/X/XI)
29
Q

What are the components of the 11th cranial nerve? [1]

A

Somatic Motor to soft palate, pharynx and larynx muscles. Also the SCM and Trapezius

30
Q

Describe the pathway of the Accessory Nerve [2]

A

Has both medullary and spinal roots

It all exits via the jugular foramen

31
Q

Clinical relevance of the accessory nerve? [2]

A

Weakness when shrugging or turning the head

32
Q

Component of hypoglossal nerve [1]

Describe the pathway of the hypoglossal nerve? [2]

A

Component: somatic motor

  • Emerges from medulla
  • Exits via hypoglossal canal (in the wall of the foramen magnum)
33
Q

Whats the clinical relevance of the 12th cranial nerve? [3]

A
  • Damaged in a tonsillectomy

- Paralyses the ipsilateral side of the tongue [1], the tip also deviates towards the affected side [1]

34
Q

What foramen do the various cranial nerves exit?

A 
I - Foramina in the Cribriform plate
II - Optic Canal
III - Sup Orbital Fissure
IV - Sup Orbital Fissure
V1 - Sup Orbital Fissure
V2 - Foramen Rotundum
V3 - Foramen Ovale
VI - Sup Orbital Fissure
VII - Internal Auditory Meatus -> Stylomastoid foramen
VIII - Internal Auditory Meatus
IX - Jugular Foramen
X - Jugular Foramen
XI - Jugular Foramen
XII - Hypoglossal Canal

Neuro (42 decks)

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