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Anatomy > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

Name CNI and its functions.
entry/exit?

A

CN1 is the olfactory nerve, responsible for the special sense of smell.
No motor innervation.
Exits via the cribiform plate of the ethmoid bone.

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2
Q

Name CN2 and its functions.
Entry/exit?

A

CN2 is the optic nerve, responsible for the special sense of sight.
No motor innervation.
Exits via the optic canal, just above the superior orbital fissure.

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3
Q

Name CN3 and its functions.
Entry/exit?

A

CN3 is the oculomotor nerve, responsible for movement of most of the eye except for the superior oblique and lateral rectus muscles.
Exits via the superior orbital fissure, just lateral/inferior to the optic canal.

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4
Q

Name CNIV and its functions.
Entry/exit?

A

CN4 is the trochlear nerve, responsible for movement of the superior oblique.
Exits via the superior orbital fissure, just lateral/inferior to the optic canal.

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5
Q

Name CNV and its functions.
Entry/exits?

A

CN5 is the trigeminal nerve with 3 branches, responsible for sensory innervation of the forehead, partially the face, and motor/sensory of the mandible.
Exits via the superior orbital fissure, the foramen rotundum, and the foramen ovale.

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6
Q

What is V1 and its functions?
entry/exit?

A

V1 is the first branch of the trigeminal nerve, consisting of the NFL,
Nasociliary nerve - anterior/posterior ethmoidal nerves (nasal pain) and long/short ciliary nerve (eye pain)
Frontal nerve - (Supraorbital nerve and supratrochlear nerve)
Lacrimal nerve
Exits from the superior orbital fissure.

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7
Q

What is V2 and its functions?

A

V2 is the second branch of the trigeminal nerve, consisting of PIPZ
Posterior superior alveolar nerves (teeth)
Infraorbital nerve - (anterior and middle superior alveolar nerves (teeth)
Palatine nerves (greater and lesser)
Zygomatic nerves (has a branch to lacrimal)
Exits via the foramen rotundum.

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8
Q

What is V3 and its functions?
exit?

A

V3 is the third branch of the trigeminal nerve, consisting of ALIMB,
Auriculotemporal nerve
Lingual Nerve
Inferior Alveolar Nerve - (mental nerve)
Buccal Nerve
Muscular Branches
Exits via the foramen ovale.

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9
Q

Describe how trigeminal neuralgia occurs and the symptoms associated.

A

It is diagnosed by hypersensitivity to pain, occurring along any branch of CNV. Intense shooting pain triggered by light touch/cold air.
Most common cause is a blood vessel pushing against a branch.

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10
Q

What muscles does the mandibular branch (V3) innervate?

A

Muscles of mastication: masseter, temporalis, lateral/medial pterygoids.
Tensor veli palatini, tensor tympani, anterior belly of digastric, and mylohyoid.

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11
Q

How can I diagnose a lesion of the mandibular nerve?

A

Loss of bite strength, jaw deviation towards lesioned side when open.

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12
Q

How can I diagnose a lesion of CNI?

A

Loss of smell.

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13
Q

How can I diagnose a lesion of CN2?

A

Extreme loss of vision in one eye.

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14
Q

What occurs if I have a lesion in my optic tracts?

A

Example: A lesion in my left optic tract could result in a loss of right sided vision in both eyes.

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15
Q

What occurs if I have a lesion in my optic chiasm?
MC?

A

I would lose the lateral half of my visual field in each eye because my nasal retina would be affected.
MC: Pituitary tumor.
This is known as bitemporal hemianopia.

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16
Q

How does decussation work for my visual field?

A

The nasal/medial part of each visual field decussates at the optic chiasm.
This means the medial half of your right visual field is controlled by the left side of your brain.
However, the lateral half of your right visual field is controlled by the right half of your brain.

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17
Q

How does decussation work for my visual field?

A

The temporal visual field decussates at the optic chiasm.
This means the nasal visual field is controlled by the same side of your brain.
However, the temporal visual field is controlled by the opposite half of your brain.

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18
Q

Where do my optic nerves aggregate after the optic chiasm?

A

Lateral geniculate nuclei of the thalamus

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19
Q

What part of my retina receives the lower half of my visual field?

A

My upper retina.

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20
Q

Why is retinal detachment possible?

A

Double layering of the eye during development.
The retina is actually an extension of the diencephalon during development. The lens is made from epidermal tissue.

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21
Q

Why is smell related to memory?

A

Smell goes straight to the temporal lobe, skipping the thalamus.

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22
Q

What are the special senses?

A

Smell (CN1)
Vision (CN2)
Hearing/Balance (CN8)
Taste (CN7, 9, 10)

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23
Q

Why can our eye get melanoma?

A

It contains a pigmented epithelium.

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24
Q

What does a lesion of a single optic radiation cause?

A

Quadrantanopia
Loss of one quarter of the visual field, same side in both eyes (since decussation has already occurred)

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25
Q

What CN controls pupillary constriction?

A

CN3, oculomotor

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26
Q

What does an oculomotor lesion present as and the main causes?

A

An eye directed down and out.
MC: Posterior communicating artery aneurysm.

Other possibilities include a posterior cerebral and/or superior cerebellar artery aneurysm.

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27
Q

What does a trochlear lesion present as?

A

Double vision when looking in and down.
Patients will have a habitual head tilt away from affected side.

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28
Q

What does an abducens nerve lesion present as?
MC?

A

Double vision when looking laterally.
Eye cannot look laterally past the midline.
MC: Internal carotid aneurysm in the cavernous sinus.

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29
Q

What is an early sign of increased intracranial pressure?

A

Loss of parasympathetic innervation to an eye. CNIII will be compressed against the dura mater.

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30
Q

What does relaxation of the lens do?

A

Flattening.

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31
Q

What CNs does an inflamed cavernous sinus possibly affect?

A

CNIII, CNIV, V1, V2, and CNVI

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32
Q

Where is my visual cortex located?

A

Occipital lobe, specifically the striate area by the calcharine sulcus.

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33
Q

What is CNVII and its functions?
entry/exit?

A

The facial nerve, innervating the six branches of the facial muscles, sensory to the ear (partially), taste to the ANTERIOR tongue (2/3), and innervation to the lacrimal, submandibular, and sublingual glands.
It enters via the internal acoustic meatus and exits via the stylomastoid foramen.

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34
Q

What are the six branches of CNVII?

A

Two Zebras Bit My Cookies Again

Temporal
Zygomatic
Buccal
Mandibular
Cervical
Posterior auricular

35
Q

At what point can every branch of CN7 be affected?

A

Stylomastoid foramen (which is where it exits the skull)

36
Q

What is Bell’s palsy, and how can I differentiate between a peripheral and central palsy?

A

Peripheral Bell’s Palsy: Only affects the same side as the lesion. (inability to close left eye, wrinkles on left forehead, dropping left lip, etc…)

Central: Wrinkles on both sides of the forehead even if everything else is one sided. (IMPORTANT!)

37
Q

What does deinnervation of CN7 do to my ear?

A

Hyperacusis, as the facial nerve innervates the stapedius muscle.

38
Q

What are the parasympathetic innervations that the facial nerve carries?

A

Greater petrosal nerve -> lacrimal nerve
Chorda tympani -> submandibular and sublingual glands.

These two split just after the internal acoustic meatus.

39
Q

What does a lesion to my greater petrosal nerve affect and what is the common symptom?

A

Dry eye.
Affects the lacrimal nerve

40
Q

What does a lesion to just my facial nerve after the stylomastoid foramen affect and the common symptom?

A

Muscular innervation to one side of my face.
Bell’s palsy to one side.

41
Q

What does a lesion to my facial nerve at the internal acoustic meatus affect and the common symptom?

A

Total innervation to one side of my face.
Bell’s palsy to one side + Dry eye + hyperacusis + altered taste on anterolateral 2/3 of my tongue.

42
Q

What does a lesion before my chorda tympani but after my branching of my facial nerve cause and the common symptom?

A

Major innervation to one side of my face.
Bell’s Palsy
Hyperacusis
Altered taste on anterolateral 2/3 of my tongue.

43
Q

What does a lesion of my chorda tympani affect and the common symptom?

A

Loss of innervation to anterolateral tongue + saliva
Altered taste on anterolateral 2/3 of my tongue
and loss of salivation (aside from parotid)

44
Q

What does a lesion of my temporal and zygomatic branches of my facial nerve affect and its common symptoms?

A

Loss of ability to blink on one side only.

45
Q

Which nerve branch of CNVIII is responsible for position, equilibrium, acceleration?

A

Vestibular nerve

46
Q

Which nerve branch of CN8 is responsible for hearing?

A

Cochlear nerve

47
Q

What is CNVIII and its functions?
entry/exit?

A

Vestibulocochlear nerve
Vestibular nerve + Cochlear nerve
Responsible for position, equilibrium, acceleration, and hearing.
Enters via the internal acoustic meatus

48
Q

What two nerves enter via the internal acoustic meatus?

A

Facial nerve (CN7) and Vestibulocochlear nerve (CN8)

49
Q

What is a possible cause of a proximal facial nerve lesion and what symptoms/nerves does it affect?

A

An acoustic neuroma/schwannoma
Affects both the facial nerve and vestibulocochlear nerves (7 & 8), which enter via the internal acoustic meatus.
Loss of hearing/balance + Dry eye, hyperacusis (if hearing is not gone), loss of taste on anterior 2/3 + facial palsy.

Only facial palsy if the lesion is post stylomastoid foramen!

50
Q

What nerves make up innervation of the external ear?

A

V3, 7, and upper cervical spinal nerves.

51
Q

What are the 5 parts of an ear?

A

Helix, anti-helix, tragus, anti-tragus, and external acoustic meatus.

52
Q

What nerves make up the innervation of the ear canal?

A

7 & 10

53
Q

What are the three middle ear bones?

A

Malleus, Incus, Stapes

54
Q

What muscle does V3 innervate in the ear?

A

Tensor tympani muscle, which attaches to the handle of the malleus.

55
Q

Name the auricular pathway for detecting a change in acceleration.

A

Semicircular canals -> ampullae -> change in acceleration.

56
Q

Name the auricular pathway for detecting a change in position relative to gravity.

A

Saccule and utricle -> Maculae -> position in space relative to gravity.

57
Q

Name the auricular pathway for hearing.

A

Cochlea -> Organ of corti -> hearing

58
Q

Describe the process in the ear for detecting a change in position.

A

Within the saccule and utricle, there are maculae, which consist of gelatinous plates with sensory cilia embedded in their base and otoliths (crystalline deposits) on the other end.
All the cilia are oriented in different ways, causing different rates of depolarization and hyperpolarization.

SUP (Saccule, utricle, position)

59
Q

What is the only CN that exits dorsally?

A

CN4, Trochlear

60
Q

What is the exit point for CN IX, X, and XI?

A

Jugular foramen

61
Q

What is CNIX and its functions?

A

Glossopharyngeal nerve
Sensory to pharynx and middle ear & inner ear
Motor to stylopharyngeus
Taste and sensation to posterior 1/3 tongue
Innervates parotid gland
Innverates baro and chemoreceptors in the carotid.

62
Q

Describe the pathway CNIX takes to get to the parotid gland.

A

CNIX exits via the jugular foramen and loops up through the tympanic nerve/plexus, going to the lesser petrosal nerve, then the otic ganglion. It then passes through the foramen ovale to the auriculotemporal to go to the parotid.

63
Q

What is CNX and its functions?
entry/exit?

A

Motor to pharynx, larynx, and esophagus
Sensory to larynx and esophagus
Innervates aortic baroreceptors
Motor & sensory to all thoracic organs, foregut, and midgut.
Exits via jugular foramen.

64
Q

If I had a lesion below C1, what CN would be affected and what would the symptoms be?

A

CNX
Increased heart rate
Decreased gut peristalsis & sounds
Decreased secretions from digestive glands

65
Q

What two CNs innervate the gag reflex?

A

Pharyngeal plexus, which is made up CNIX (Sensory) and CNX (Motor)

66
Q

How do I test a gag reflex?

A

Touch the posterior wall of the pharynx, tonsillar area, and posterior tongue with a tongue depressor. Muscle contraction implies reflex is intact.

67
Q

What pharyngeal muscles does CNX innervate?

A

Pharyngobasilar fascia
Ptergomandibular raphe
Superior pharnyngeal constrictor
Middle pharyngeal constrictor
Thyrohyoid membrane
Inferior pharyngeal constrictor
Cricopharygneus muscle
Levator veli palatini muscle
Salpingopharyngeus
Palatopharyngeus
Laryngeal muscles (CNX)

68
Q

What pharyngeal muscles does CNIX innervate?

A

Only stylopharyngeus

69
Q

What is a common sign of vagus nerve weakness?

A

Uvula deviation.
The affected side will appear tilted downwards.

70
Q

What muscles and innervation are used in mastication and swallowing?

A

CN I, V3, VII, IX, X, XII

71
Q

What CN innervates the larynx?

A

CNX via the inferior laryngeal nerve (from recurrent) innervates ALL intrinsic laryngeal muscles
EXCEPT
superior laryngeal nerve (external), which innervates the cricothyroid.

Sensory is from the internal branch of the superior laryngeal nerve.

72
Q

What muscle pulls apart the vocal cords?

A

Posterior cricoaretynoid muscle (only muscle that abducts the vocal cords)

73
Q

How many vocal folds do we have and what is the space between called?

A

2, ventricles (creates resonance)

74
Q

What is the purpose of the cricothyroid muscle and what is its innervation?

A

It is innervated by external branch of the superior laryngeal nerve
It is responsible for pitch, so de-innervation would cause monotone speech.

75
Q

What is the purpose of vocal fold abduction and what muscle does it?

A

Posterior cricoaretynoid muscle.
Raise the volume or breathe heavily
Innervated by the inferior laryngeal nerve.
De-innervation causes hoarseness.

76
Q

What muscles control fine vocal modulation and how?
Innervation?

A

Vocalis and thryoaretynoids loosen the vocal folds on contraction.
Innervated by inferior laryngeal nerve

77
Q

What function do the lateral cricoaretynoids and aretynoids do and what is their effect?
Innervation?

A

Adduct the vocal folds, contracting when we breathe quietly or lower our voice.
Innervated by inferior laryngeal nerve

78
Q

What is CNXI and what does it do?

A

The spinal accessory nerve originates from C1-5 levels. The axons ascend via the foramen magnum, but exit through the jugular foramen.
Innervation of SCM and Traps

79
Q

What is CNXII and what does it do?

A

Hypoglossal nerve, exiting via the hypoglossal canal and innervate all tongue muscles but the palatoglossus (vagus)

80
Q

What muscle is tested for CNXII intactness and what does it do?

A

Genioglossus, it will appear deviated towards its affected side when CNXII is lesioned on a side.

81
Q

What nerves make up the cervical plexus?

A

C1-3

82
Q

What does the cervical plexus innervate?

A

Muscles near the hyoid involved in swallowing.
Forms the ansa cervicalis, anterior to the carotid sheath.
C1 axons hitchike on CNXII as well.
Sensory of neck, ear, clavicles, and posterolateral scalp.

83
Q

Explain the sensory innervation of the tongue

A

Epiglottis: general sensation and taste by CNX.
Posterior 1/3: general sensation and taste by CNIX
Anterior 2/3: General sensation by lingual branch, which is part of V3.
Taste is by the chorda tympani of CNVII.

84
Q

List all the exit points of the cranium and the CNs that exit through them.

A

CNI: Cribiform plate of ethmoid bone.
CNII: Optic Foramen
CNIII, CNV1, CNIV, CNVI: Superior orbital fissure
CNV2: Foramen Rotundum
CNV3: Foramen Ovale
CNVII, CNVIII: Internal auditory meatus
CNIX, CNX, CNXI: Jugular foramen
CNXII: Hypoglossal canal

Anatomy (19 decks)

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