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Neuro > Cranial nerves > Flashcards

Cranial nerves Flashcards

1
Q

Order

A 
Olfactory 
Optic 
Oculomotor
Trochlear 
Trigeminal 
Abducens 
Facial 
Vestibulocochlear 
Glossopharyngeal
Vagus 
Accessory 
Hypoglossal
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2
Q

Mnemonic for sensory, motor or both

A

Some Say Money Matters, But My Brother Says Big Boobs Matter More

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3
Q

Which cranial nerves are not organised in the brainstem?

A

CN1 and CN2 → originate in the forebrain

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4
Q

What is a cranial nerve nucleus?

A

A collection of neurons in the brainstem that is associated with one or more cranial nerves

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5
Q

What does the sulcus limitans do?

A

Separates the cranial nerve motor nuclei (medial) from sensory nuclei (lateral)

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6
Q

Which cranial nerves are found laterally in the brainstem?

A

Sensory

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7
Q

Which cranial nerves are found medially in the brainstem?

A

Motor

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8
Q

What are the sensory cranial nerve nuclei?

A

Trigeminal sensory nucleus
Vestibular nucleus and cochlear nucleus
Nucleus solitarius

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9
Q

Describe the trigeminal sensory nucleus?

A
  • large → runs the length of the brainstem
  • carry general sensory information (touch, pressure, pain, temperature) from the head enter through the trigeminal nerve
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10
Q

Describe the vestibular and cochlear nuclei

A
  • termination of fibres conveying the special senses of motion/positional sense and hearing
  • from the vestibulocochlear nerve
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11
Q

What terminates in the nucleus solitarius?

A

visceral afferents, including taste fibres

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12
Q

What three groups can motor cranial nerve nuclei be divided into?

A
  • nuclei of the somatic efferent cell column (near the midline)
  • nuclei of the branchiomotor cell column (furthest out)
  • nuclei of the parasympathetic cell column
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13
Q

What are the nuclei of the somatic efferent cell column?

A
  • Oculomotor nucleus
  • Trochlear nucleus
  • Abducens nucleus
  • Hypoglossal nucleus
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14
Q

What are the nuclei of the branchiomotor cell column?

A

Trigeminal motor nucleus
Facial motor nucleus
Nucleus ambiguus

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15
Q

What are the nuclei of the parasympathetic cell column?

A
  • Edinger-Westphal nucleus
  • Superior and inferior salivary nuclei
  • Dorsal motor nucleus of the vagus
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16
Q

Draw the nuclei

A

OneNote - under anatomy

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17
Q

Describe the oculomotor nucleus

A

Efferents run in the oculomotor nerve to innervate the EXTRAOCULAR MUSCLES (levator palpebrae, superioris muscle, superior rectus, inferior rectus, medial rectus and inferior oblique) except the superior oblique and the lateral rectus

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18
Q

Describe the trochlear nucleus

A

fibres leave in the trochlear nerve and innervate the superior oblique muscle of the eye

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19
Q

Describe the abducens nucleus

A

efferent run in the abducens nerve and innervate the lateral rectus muscle

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20
Q

Describe the hypoglossal nucleus

A

innervates the intrinsic and extrinsic muscles of the tongue via the hypoglossal nerve

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21
Q

What does the branchiomotor cell column innervate?

A

Striated muscles derived from the embryonic branchial (pharyngeal) arches

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22
Q

Describe the trigeminal motor nucleus

A

supplies fibres to the trigeminal nerve and innervates muscles of mastication, tensor tympani etc

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23
Q

Describe the facial motor nucleus

A

innervates the muscles of facial expression and the stapedius muscle via the facial nerve

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24
Q

Describe the nucleus ambiguus

A

Motor fibres to the glossopharyngeal, vagus and cranial part of the accessory nerve to innervate muscles of the pharynx and larynx

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25
Q

What do the nuclei of the parasympathetic cell column consist of?

A

Preganglionic parasympathetic neurones that send axons into the III, VII, IX and X cranial nerves

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26
Q

Describe the Edinger-Westphal nucleus

A

leave the brainstem in the oculomotor nerve and pass to the ciliary ganglion in the orbit, within which they synapse, from here, postganglionic fibres innervate the sphincter pupillae and ciliary muscles within the eye

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27
Q

Describe the superior and inferior salivary nuclei

A

Superior → supplies preganglionic fibres to the facial nerve

Inferior → glossopharyngeal nerve

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28
Q

Describe the dorsal motor nucleus of the vagus

A

fibres leave in the vagus nerve and are widely distributed to thoracic and abdominal viscera §

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29
Q

Foramen associated with olfactory nerve

A

Cribiform plate

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30
Q

Foramen associated with optic nerve

A

Optic canal

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31
Q

Foramen associated with oculomotor

A

Superior orbital fissure

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32
Q

Foramen associated with trochlear

A

Superior orbital fissure

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33
Q

Foramen associated with trigeminal

A 
Superior orbital fissure (opthalmic)
Foramen rotundum (maxillary)
Foramen ovale (mandibular)
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34
Q

Foramen associated with abducens

A

Superior orbital fissure

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35
Q

Foramen associated with facial

A

Internal auditory meatus

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36
Q

Foramen associated with vestibulocochlear

A

Internal auditory meatus

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37
Q

Foramen associated with glossopharyngeal

A

Jugular foramen

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38
Q

Foramen associated with vagus

A

Jugular foramen

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39
Q

Foramen associated with accessory

A

Jugular foramen

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40
Q

Foramen associated with hypoglossal

A

Hypoglossal canal

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41
Q

Describe the path of the olfactory nerve

A

olfactory receptors in nasal epithelium/mucosa → axons penetrate cribiform plate → olfactory bulb → olfactory tract → this can split into lateral stria (carries axons to the primary olfactory cortex, located within the uncus of the temporal lobe) and the medial stria (carries axons across the medial plane of the anterior commissure, where they meet the olfactory bulb of the opposite side)

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42
Q

What do the fila olfactoria synapse with in the olfactory bulb and what do they form?

A

synapse with mitral cells to form synaptic glomeruli

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43
Q

Describe the optic nerve

A

optic nerve leaves the orbit via the optic canal → optic chiasm (partial decussation) → lateral geniculate nucleus (relay to visual cortex), pretectal nucleus (reflexive eye movements), suprachiasmatic nucleus (sleep-wake)
- will cover optic nerve in more detail in vision module

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44
Q

What nerves are involved in control of eye movement?

A
  • oculomotor (III)
  • trochlear (IV)
  • abducens (VI)
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45
Q

Tests for oculomotor, trochlear and abducens nerves

A

Examine pupillary reflexes and eye movements

46
Q

Describe path of oculomotor nerve

A

oculomotor nucleus → leaves the cranial cavity via the superior orbital fissure → divides into superior (superior rectus and levator palpabrae superioris) and inferior (inferior rectus, medial rectus and inferior oblique + preganglion to ciliary ganglion)

47
Q

Describe the functions of the muscles the oculomotor nerve innervates

A

Superior rectus → elevates the eyeball
Levator palpabrae superioris → raises the upper eyelid

Inferior rectus → depresses the eyeball
Medial rectus → adducts the eyeball (or medially rotates it)
Inferior oblique → elevates, abducts and laterally rotates the eyeball

48
Q

Describe the parasympathetic inneravion in the oculomotor nerve

A

Originates in the Edinger-Westphal nucleus

  • sphincter pupillae → constricts the pupil
  • ciliary muscles → contracts, causes lens to become more spherical (more for short-range vision) → this is the accomodation reflex
49
Q

Which branch of the oculomotor nerve do the pre-ganglionic parasympathetic fibres travel in? Where do they synpase?

A

Inferior

In the ciliary ganglion (behind the orbit)

50
Q

What happens following damage to cranial nerve III

A
  • DOWNWARD and LATERAL deviation of the eye due to unopposed action of the lateral rectus and superior oblique
  • DILATED PUPIL
  • loss of levator palpebrae causes drooping of eyelid → ptosis
51
Q

At what level of the brainstem is the oculomotor nucleus?

A

Level of superior colliculus

52
Q

Mnemonic for cranial nerves controlling eye movement

A

LR6 (lateral rectus - VI)
SO4 (superior oblique - IV)
ATR3 (all the rest - III)

53
Q

Describe pathway of trochlear nerve

A

arises in trochlear nucleus of brain → decussate → lateral wall of cavernous sinus (along with oculomotor nerve, abducens nerve, the ophthalmic and maxillary branches of the trigeminal and internal carotid) → enters orbit through superior orbital fissure → innervates superior oblique

54
Q

Damage to trochlear nerve

A

DIPLOPIA WHEN LOOKING DOWNWARD AND MEDIALLY

55
Q

At what level of the midbrain is the trochlear nucleus?

A

At the level of the inferior colliculus

56
Q

Which is the only cranial nerve to emerge from the dorsal aspect of the brainstem?

A

Trochlear

57
Q

3 functions of superior oblique

A
  • internal rotation (intorsion)
  • depression
  • laterally rotates
58
Q

What can the peripheral aspect of the trigeminal ganglion give rise to?

A

3 divisions:

1) ophthalmic (V1)
2) maxillary (V2)
3) mandibular (V3)

59
Q

What are the three nuclei that the trigeminal sensory nucleus can be divided into?

A
  • nucleus of the spinal tract of the trigeminal
  • principal sensory nucleus
  • mesencephalic nucleus
60
Q

Which division of the trigeminal nerve pass through the lateral wall of the cavernous sinus?

A

V1 and V2

61
Q

Discuss path of V1

A

superior orbital fissure → gives off 3 branches → nasociliary, lacrimal, frontal

62
Q

What does the lacrimal branch do?

A
  • runs outside the annulus of Zinn on the temple (LATERAL SIDE) side of the superior orbital fissure → pierces through the lacrimal gland & gives off a branch to supply the SKIN of the superior palpebrae and underlying CONJUCTIVA
63
Q

What does the frontal branch do?

A
  • Runs through the superior orbital fissure outside the annulus of Zinn, medial to the lacrimal nerve

Branches

  • supra-trochlear nerve - supplies conjuctiva and skin of palpebrae (same as lacrimal) & SKIN OF FOREHEAD
  • supra-orbital - conjuctiva and skin of palpebrae (again) & skin of the forehead & TOP OF THE HEAD
64
Q

What does the nasociliary branch do?

A

runs between the superior and inferior branch of the oculomotor nerve inside of the annulus of Zinn

Branches

  1. short ciliary nerves & long ciliary nerves (cornea)
  2. posterior and anterior ethmoidal nerves (the sinus)
  3. anterior ethmoidal branches further and supplies the nose
  4. infero-trochlear nerve → medial upper eyelid & lacrimal sac & lacrimal caruncle

JUST REMEMBER LACRIMAL

65
Q

What are the 3 nerves that run through the superior orbital fissure but outside the annulus of Zinn?

A

Lacrimal
Frontal
Trochlear
LIVER FAILURE TEST

66
Q

Where does V2 go through after the cavernous sinus?

A

Foramen rotundum (although there is a branch before it enters - DURAL BRANCH - that supplies the dura mater)

67
Q

Describe V2 innervation after entering the foramen rotundum

A
  1. Infraorbital nerve → maxilla and upper lip
  2. Zygomatic nerve (temple, cheek)
    These move through inferior orbital fissure
  3. Alveolar nerve (hard palate, molars)
  4. Palatine → nasal cavity and palate
68
Q

Where does V3 move though in the skull?

A

Foramen ovale

69
Q

Describe sensory part of V3

A
  • external ear & temple region
70
Q

Describe motor part of V3

A
  1. Muscles of mastication
  2. Through mandibular foramen → lower teeth (sensory), skin of the chin (sensory), muscles surrounding hyoid bone (these are motor)
  3. lingual nerve → ANTERIOR 2/3 OF TONGUE (SENSORY)
71
Q

Describe termination of thermoceptive and nocicpetive fibres of the trigeminal nerve?

A

terminate in the spinal nucleus → second order axons project to the contralateral thalamus

72
Q

Where do proprioceptive axons for spindles and golgi organs in the muscles of mastication terminate?

A

in the mesencephalic trigeminal nucleus

73
Q

What is sensory trigeminal innervation responsible for?

A

toothache
headache
migraine
trigeminal neuralgia

74
Q

How is trigeminal sensory innervation tested?

A

integrity and symmetry of pain and light tough from all three areas of the face

75
Q

How is trigeminal motor innervation tested?

A

jaw opening against resistance, and examining for symmetry and strength

76
Q

What does the abducens nerve innervate?

A

Lateral rectus (motor)

77
Q

Describe path of abducens nerve

A

abducens nucleus in the pons → moves in Dorello’s canal → IN THE CAVITY OF THE cavernous sinus → superior orbital fissure → lateral rectus

78
Q

What does the lateral rectus do?

A

Abduct the eyeball (rotate gaze away from the midline)

79
Q

Damage to cranial nerve 6

A

medial deviation of the eye due to unopposed action of the medial rectus

80
Q

Test for abducens nerve

A

Examine pupillary reflexes and eye movements

81
Q

What pharyngeal arch is the facial nerve associated with?

A

2nd

82
Q

Describe broadly what the different divisions of the facial nerve do?

Describe their pathways

A

Motor: muscles of facial expression, digastric, stylohyphoid and stapedius

Originates in facial motor nucleus → goes around and behind CNVI (facial colliculus) → internal acoustic meatus → facial canal (branch from stapedius) → gives off branches:

  • temporal → forehead + eyebrow + eye
  • zygomatic → eye + cheek
  • buccal → mouth
  • marginal mandibular → chin
  • cervical → neck

Sensory: small area around the concha of the auricle & internal acoustic meatus

  • ear area → geniculate ganglion → internal acoutic meatus → spinal nucleus of trigeminal system

Special sensory: TASTE sensation to anterior 2/3 of the tongue (VIA CHORDA TYMPANI)

Taste buds → petrotympanic fissure → posterior and anterior cannaliculi → facial canal → internal coustic meatus → NTS

Parasympathetic: supplies many of the glands of the head and neck, including:

  • submandibular and sublingual salivary glands (VIA CHORDA TYMPANI AND SUBMANDIBULAR GANGLION)
  • nasal, palatine and pharyngeal mucus glands
  • lacrimal glands (VIA PTERYGOPALATINE GANGLIA)

Superior salivary nucelus → internal acoustic meatus → facial canal → petrotypanic fissure → submandibular & sublingual gland (submandibular ganglion) - sensory so opposite direction

Also → through hiatus → foramen lacerum → pterygopalatine fossa → pterygopalatine ganglion → inferior orbital fissure → lacrimal gland + nasal glands + palatine)

83
Q

Origins of motor facial nerve

A

Facial motor nucleus

84
Q

Origins of parasympathetic facial nerve

A

Superior salivatory nucleus

85
Q

Origins of sensory facial nerve component

A

NTS

86
Q

Evaluating facial nerve lesions

A

observing the action of facial muscles [closing eyelids, puffing cheeks, symmetry of motions] - facial muscles are differently affected by peripheral and central nerve lesions
• Lower face paralysis indicates a central lesion
• Entire face paralysis - peripheral nerve lesion

87
Q

What may lesions of the facial nerve lead to?

A

Bell’s palsy → loss of control of facial muscles on one side of face
Can have hyperacusis

88
Q

Describe hyperacusis

A

The loss of stapedius control can occur due to facial nerve palsies and leads to increased sensitivity to certain sound frequencies(may become too painful or loud)

89
Q

Describe nerves supplying the pharyngeal arches

A 
1 - trigeminal
2 - facial 
3 - glossopharyngeal
4 - vagus
6 - vagus
90
Q

What is the chorda tympani?

A

chord that moves from the posterior to the anterior wall of the tympanic cavity
- consists of sensory (taste) and parasympathetic (glands) facial nerve

91
Q

Where does the vestibulocochlear originate?

A
  • vestibular = vestibular nuclei complex
    -cochlear - central and dorsal cochlear nuclei
    these combine in the pons to form the vestibulocochlear nerve
92
Q

Pathway of vestibular nerve

A

hair cells → internal acoustic meatus → vestibular nucleus in the medulla (composed of superior, inferior, lateral, medial) → four destinations:

  1. lateral vestibular nucleus (some from medial) → lateral vestibulospinal tract
  2. inferior cerebellar peduncle - flocculonodular lobe → fastigial nucleus (can also return fibres to the vestibular nuclei)
  3. Medial vestibular nucleus → nuclei of abducens → connections with contralateral oculomotor and trochlear → coordination of eye and head movements (this is the medial longitudinal fasciculus)
  4. to thalamus VPM → internal capsule → cortex
93
Q

Describe pathway of cochlear nerve

A

organ of corti → spiral gangia → internal acoustic meatus → dorsal and ventral cochlear nuclei
1. dorsal nuclei → contralateral nucleus of lateral lemniscus
2. ventroposterior nucleus → carry on upwards
3. anterovental nucleus → superior olivary nucleus
These all form a tract called the LATERAL LEMNISCUS → inferior colliculus → medial geniculate nucleus (ears are lateral so nucleus is medial) → superior temporal gyrus

94
Q

Describe acoustic neuromas

A

Most common tumours of ear - grow in the auditory canal due to Schwann cells - loss of hearing and diequilibrium

95
Q

Tests for vestibulocochlear nerve

A

audiometry, use of tuning fork to distinguish sensorineural and
conductive hearing loss

96
Q

Tests for vestibular function

A

caloric or rotational tests; nystagmus

97
Q

Draw the effects of oculomotor, trochlear and abducens lesions on the eyes

A

OneNote

98
Q

Summarise the functions of the glossopharyngeal nerve and pathways

A

Sensory: Innervates the oropharynx, carotid body and sinus, posterior 1/3 of the tongue, middle ear cavity and Eustachian tube

→ spinal nucleus of the trigeminal nerve (middle ear)

→ posterior 1/3 of tounge, oropharynx, baroreceptors and chemoreceptors (carotid sinus+body) → jugular foramen → NTS & dorsal nucleus of vagus

Special sensory: Provides taste sensation to the posterior 1/3 of the tongue

Poster tongue → jugular foramen → NTS

Parasympathetic: Provides parasympathetic innervation to the parotid gland.

Inferior salivatory nucleus → jugular foramen → through the tympanic cavity → haitus of lesser petrosal nerve → foramen ovale → parotid gland

Motor: Innervates the stylopharyngeus muscle of the pharynx

Nucleus ambiguus → jugular foramen → stylopharyngeus (pulls pharynx upwards)

99
Q

Test for cranial nerve IX and X

A

Gag reflex - afferents are carried by the glossopharangeal nerve, with the motor efferents by the vagus

100
Q

Functions and pathway of vagus nerve

A

Sensory: Innervates the skin of the external acoustic meatus and the internal surfaces of the
laryngopharynx and larynx.
→ jugular foramen → spinal nucleus of the trigeminal nerve

Provides visceral sensation to the heart and abdominal viscera.

Special Sensory: Provides taste sensation to the epiglottis and root of the tongue.
→ jugular foramen → NTS

Motor: Provides motor innervation to the majority of the muscles of the pharynx, soft palate and larynx.
→ nucleus ambiguus → pharyngeal constrictors & speech production w/ larynx

Parasympathetic: Innervates the smooth muscle of the trachea, bronchi and gastro-intestinal tract and regulates heart rhythm.

101
Q

Which nerve supplies the laryngeal muscles which control the vocal folds?

A

Recurrent laryngeal nerve

102
Q

Describe lesions of vagus nerve

A

Lesions centrally, or unilateral peripheral lesions tend to produce minimal effects due to the bilateral innervation of PS viscera

103
Q

What does the accessory nerve innervated?

A

Sternocleidomastoid and trapezius muscles

104
Q

Describe path of accessory nerve

A

Cranial part leaves nucleus ambiguus → jugular foramen → combines with the vagus nerve → pharyngeal constrictors

Spinal part = originates from C1-5/6 spinal roots → foramen magnum → jugular foramen → descends along the internal carotid → reaches sternocleidomastoid (also gets innervation straight from C2 and C3)

Trapezius gets branches from C3 and C4

105
Q

Tests for accessory

A

Actions of sternomastoid and trapezius muscles

106
Q

What are the actions of sternocleidomastoid and trapezius muscles?

A 
trapezius = elevates scapula 
sternocleidomastoid = rotation of head to contralateral side and flexion of the neck
107
Q

What is the function of the hypoglossal nerve?

A

Innervation of all extrinsic and intrinsic muscles of the tongue (apart from palatoglossus which is CN X)

108
Q

Discuss path of hypoglossal

A

hypoglossal nucleus → hypoglossal canal → crosses external carotids → mves towards the tongue

109
Q

Lesion of hypoglossal

A

lesions of the primary motor cortex/internal capsule leads to ipsilateral tongue weaknesses where protrusion is associated with deviation to the weak side

110
Q

Which cranial nerves have parasympathetic components? What do they do

A

III - pupil constriction
VII - salivary and lacrimal glands
IX - salivary glands
X - viscera

Neuro (23 decks)

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