Cranial nerves Flashcards

1
Q

What is the primary function of Cranial Nerve I (CN I)?

A

Smell
* Sensory in function

Responsible for the sense of smell (olfaction)

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2
Q

How is the integrity of Cranial Nerve I tested?

A

Have the patient close their eyes and occlude a nostril, present an aromatic agent, and ask for identification

Repeat the process with the other nostril using a different aromatic agent

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3
Q

What substances are commonly used to test olfaction?

A
  • Vanilla
  • Mint oil
  • Coffee
  • Chocolate

The aromatic substances should not be irritating

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4
Q

What can cause a unilateral loss of olfaction?

A

Meningiomas

These tumors affect the olfactory nerve

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5
Q

What factors may lead to bilateral loss of olfaction?

A
  • Obstruction of the nasal passage
  • Heavy smoking
  • Rhinitis (stuffy nose)
  • Hay fever
  • A cold

These conditions can affect the sense of smell

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6
Q

What is the primary function of Cranial Nerve II (CN II)?

A

Vision
* Sensory in function

Responsible for vision

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7
Q

How can the integrity of the optic nerve be assessed?

A
  • Testing visual acuity
  • Testing visual fields

Visual acuity is tested monocularly, while visual fields can be assessed using confrontation or counting finger methods

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8
Q

What is the method for testing visual acuity?

A

Performed monocularly, at distance and near, with the patient’s best correction in place

This ensures accurate measurement of vision

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9
Q

What methods can be used to test visual fields?

A
  • Confrontation method
  • Counting finger method

These methods are performed without correction in place to avoid interference

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10
Q

What should be done if a defect is noted in visual fields during testing?

A

Further quantify via automated visual field testing

This provides a more detailed assessment of visual field defects

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11
Q

What is the purpose of red cap desaturation testing?

A

To compare the level of saturation of a red target between the eyes

This test helps in assessing the integrity of the optic nerve.

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12
Q

How is red cap desaturation testing performed?

A

With one eye occluded, a red object is presented to each eye, and saturation levels are compared

The test should be conducted in a fully illuminated room.

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13
Q

What perceived difference in saturation indicates a likely afferent pupillary defect (APD)?

A

A perceived difference of 20% or more

This suggests abnormalities in the optic nerve.

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14
Q

What is assessed during the observation of the optic nerve?

A

The overall integrity and health of the optic nerve

This includes techniques such as ophthalmoscopy and fundus lenses.

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15
Q

Where is the nucleus of Cranial Nerve III located?

A

In the midbrain

CN III is also known as the oculomotor nerve.

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16
Q

What muscles does the oculomotor nerve supply?

A
  • Medial rectus
  • Superior rectus
  • Inferior rectus
  • Inferior oblique
  • Levator palpebral muscles

It is also involved in pupil and accommodative innervation.

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17
Q

What should patients not be wearing during the pupillary reaction assessment?

A

Glasses

This ensures accurate assessment of the pupillary response.

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18
Q

What is considered a normal pupillary reaction to light compared to near response?

A

More brisk

The pupillary reaction to light should be quicker than that associated with near response.

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19
Q

What is the purpose of extraocular motility testing?

A

To assess any restrictions or asymmetries in eye movement

Patients are asked to fixate on a target moved into the nine fields of gaze.

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20
Q

What should happen to both pupils when a near stimulus is presented?

A

Both pupils should constrict equally

This indicates a normal accommodative response.

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21
Q

What is the function of Cranial Nerve IV (CN IV)?

A

Motor in function

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22
Q

Where is the nucleus of Cranial Nerve IV located?

A

In the midbrain

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23
Q

What muscle does Cranial Nerve IV innervate?

A

Superior oblique muscles

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24
Q

How is the integrity of CN IV tested?

A

Assessing extraocular motility for any deficits
* superior oblique

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25
Q

What are the main functions of Cranial Nerve V (CN V)?

A

Motor and sensory functions

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26
Q

In which part of the brain is the nucleus of Cranial Nerve V located?

A

In the pons

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27
Q

What are the three main divisions of the trigeminal nerve?

A
  • Ophthalmic (V1)
  • Maxillary (V2)
  • Mandibular (V3)
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28
Q

What are the subdivisions of the ophthalmic division (V1) of CN V?

A
  • Nasociliary
  • Frontal
  • Lacrimal

NFL!!!

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29
Q

Which subdivision of V1 is most commonly affected by herpes zoster ophthalmicus?

A

Frontal division

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30
Q

What are the subdivisions of the nasociliary division of V1?

A

LINE
* Long ciliary
* Infratrochlear
* Nasal
* Posterior Ethmoid

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31
Q

What areas does the ophthalmic portion of CN V supply?

A
  • Eyes
  • Nose
  • Forehead
  • Temples
  • Paranasal sinuses
  • Nasal mucosa
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32
Q

What areas does the maxillary division of CN V supply?

A
  • Teeth
  • Cheeks
  • Lips
  • Upper jaw
  • Maxillary sinuses
  • Hard palate
  • Nasal mucosa
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33
Q

What areas does the mandibular division of CN V supply?

A
  • Teeth
  • Lip
  • Lower jaw
  • Tongue
  • Buccal mucosa
  • External ear
  • Auditory meatus
  • Meninges

*sensory innervation to lower face
*motor innervation to muscles of mastication

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34
Q

What muscles do the motor fibers of CN V supply?

A
  • Muscles responsible for mastication
  • Mylohyoid muscle
  • Anterior belly of the digastric
  • Tensor veli palatini
  • Tensor tympani
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35
Q

What is the method for testing the corneal reflex?

A

Patient’s gaze is directed away while the clinician touches the corneal surface with a cotton wisp

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36
Q

True or False: The reaction of each eye is compared during corneal reflex testing.

A

True

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37
Q

What is the function of Cranial Nerve V (CN V)?

A

Sensory and motor functions

CN V is also known as the Trigeminal Nerve and is responsible for sensation in the face and motor functions such as biting and chewing.

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38
Q

What are the three divisions of CN V?

A
  • Opthalmic division
  • Maxillary division
  • Mandibular division

Each division is responsible for sensation in different areas of the face.

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39
Q

How can CN V be assessed via superficial stimulation?

A

By brushing the jawbone, base of nostrils, and forehead with a cotton-tipped applicator

The patient should be able to locate where they were brushed.

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40
Q

What does palpation of masseter muscles assess in CN V?

A

Muscle clenching, asymmetries, and resistance to closure

Any irregularities may suggest a neurological defect.

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41
Q

What is the function of Cranial Nerve VI (CN VI)?

A

Motor function

CN VI is also known as the Abducens Nerve.

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42
Q

Where does the nucleus of CN VI lie?

A

In the pons

The pons is a part of the brainstem.

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43
Q

What muscle does CN VI supply?

A

Lateral rectus muscle

This muscle is responsible for moving the eye laterally.

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44
Q

How can CN VI be tested?

A

By assessing extraocular motility

This tests for any potential restrictions or deficits in eye movement.

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45
Q

What are the functions of Cranial Nerve VII (CN VII)?

A
  • Motor functions
  • Sensory functions
  • Parasympathetic innervation

CN VII is known as the Facial Nerve.

46
Q

Where does the nucleus of CN VII lie?

A

In the pons

This is the same location as CN VI.

47
Q

What sensory functions does CN VII relay?

A
  • Taste from the anterior 2/3rds of the tongue
  • Sensation from the parotid gland

These functions are crucial for taste and salivary gland sensation.

48
Q

What is the parasympathetic innervation provided by CN VII?

A
  • Mucous membranes and glands of the pharynx
  • Nasal cavity
  • Paranasal sinuses
  • Palate
  • Submaxillary and sublingual glands

This innervation is important for secretion of saliva and mucus.

49
Q

How is CN VII tested?

A

By assessing facial symmetry

This involves observing the face for any signs of asymmetry, particularly in the eyelids and mouth.

50
Q

What is the primary function of Cranial Nerve VII (CN VII)?

A

Motor innervation and sensory function

51
Q

How can you assess the motor innervation of the Facial Nerve?

A

Have the patient smile and wrinkle their forehead; note asymmetry or weakness

52
Q

What should you observe when the patient attempts to maintain eyelid closure?
* testing CN VII

A

Note any weakness when resisting clinician’s attempts to open eyelids

53
Q

Which substances are used to assess the sensory function of the Facial Nerve?

A

Salt, sugar, citric acid, and quinine (bitter)

salty, sweet, sour and bitter

54
Q

What is the procedure for testing the sensory function on the patient’s tongue?

A

Place crystals of substances on the anterior portion and identify taste

55
Q

When testing taste, what must the patient do between each sample?

A

Rinse thoroughly

56
Q

Fill in the blank: The Facial Nerve is also known as _______.

A

Cranial Nerve VII

57
Q

True or False: The assessment of the Facial Nerve includes both motor and sensory evaluations.

A

True

58
Q

What is the function of Cranial Nerve VIII (CN VIII)?

A

Sensory in function

CN VIII is also known as the Vestibulocochlear Nerve.

59
Q

Where is the nucleus of Cranial Nerve VIII located?

A

In the pons

60
Q

What functions are associated with Cranial Nerve VIII?

A

Responsible for hearing, balance, proprioception, and orientation in space

61
Q

What is the purpose of the cochlear testing?

A

To determine the distance at which the patient first hears the sound

62
Q

Describe the procedure for cochlear testing.

A

Clinician rubs fingers together at least 40 cm from the patient’s ear, noting when the patient first hears the sound, repeated for the other ear

63
Q

What is a normal response in cochlear testing?

A

The distance at which the patient first noticed the sound should be symmetrical

64
Q

What is Weber’s test used for?

A

To distinguish between conductive or sensorineural hearing loss

65
Q

How is Weber’s test performed?

A

A vibrating tuning fork is placed at the top of the patient’s skull

66
Q

What indicates a normal response in Weber’s test?

A

Equal perception between the ears

67
Q

If the patient locates the sound with the ear with poorer hearing, what type of loss is indicated?

A

Conductive loss

68
Q

If the sound is located with the ear with better hearing, what type of loss is indicated?

A

Sensorineural loss

69
Q

What is the function of Cranial Nerve IX (CN IX)?

A

Sensory and motor in function

70
Q

Where is the nucleus of Cranial Nerve IX located?

A

In the medulla

71
Q

What muscle do the motor fibers of Cranial Nerve IX innervate?

A

Stylopharyngeus muscle

72
Q

What areas do the sensory fibers of Cranial Nerve IX supply?

A

Pharynx, posterior 1/3rd of the tongue, soft palate, eustachian tube, tonsils, tympanic cavity

73
Q

What is the function of Cranial Nerve IX (CN IX)?

A

Sensory and motor functions

Also known as the Glossopharyngeal Nerve.

74
Q

What is tested when a patient is asked to pronounce the vowels A, E, I, O, and U?

A

Hoarseness of the voice or any abnormalities

This assesses the function of CN IX.

75
Q

What does the clinician monitor when a patient drinks water?

A

The swallowing reflex

Any abnormalities or regurgitation are considered atypical.
*testing CN IX (glossopharyngeal nerve)

76
Q

How is the gag reflex tested?

A

By lightly touching the posterior pharyngeal wall or tonsillar pillars

This may be diminished or absent in the elderly.

77
Q

What is observed during the gross observation of the soft palate?

A

Asymmetries or deviations

The patient opens their mouth for inspection.

78
Q

What is the primary function of Cranial Nerve X (CN X)?

A

Sensory and motor functions

Also known as the Vagus Nerve.

79
Q

Where is the nucleus of Cranial Nerve X located?

A

In the medulla

This is where the motor fibers originate.

80
Q

What areas does CN X convey indirect sensory information from?

A
  • Auditory meatus
  • Portion of the ear
  • Thoracic viscera
  • Abdominal viscera
  • Pharynx
  • Larynx
  • Esophagus
  • Trachea

This highlights the extensive sensory role of CN X.

81
Q

Is the testing for Cranial Nerve X different from that of Cranial Nerve IX?

A

No, testing is identical

Both nerves are tested similarly.

82
Q

What is the function of Cranial Nerve XI (CN XI)?

A

Motor function

Known as the Accessory Nerve.

83
Q

Where is the nucleus of Cranial Nerve XI located?

A

In the medulla

This is responsible for its motor output.

84
Q

Which muscles are supplied by Cranial Nerve XI?

A
  • Sternocleidomastoid
  • Trapezius

These muscles are crucial for neck and shoulder movement.

85
Q

What is the function of Cranial Nerve XI (Accessory Nerve)?

A

Motor function

CN XI is primarily responsible for shoulder shrugging and head turning.

86
Q

How is the strength of shoulder shrug tested in Cranial Nerve XI?

A

The patient is asked to shrug shoulders against clinician’s downward pressure

This tests the trapezius muscle, which is innervated by CN XI.

87
Q

What muscle is palpated during the head-turning test for Cranial Nerve XI?

A

Sternocleidomastoid muscle

The clinician observes for atrophy or abnormalities.

88
Q

What indicates paralysis during the head tilt test for Cranial Nerve XI?

A

Chin turns towards the side of paralysis

This reflects weakness in the affected side’s muscle.

89
Q

What is the primary function of Cranial Nerve XII (Hypoglossal Nerve)?

A

Motor function

CN XII innervates the muscles of the tongue.

90
Q

Where is the nucleus of Cranial Nerve XII located?

A

In the medulla

This is part of the brainstem.

91
Q

What is one way to assess the integrity of Cranial Nerve XII?

A

Patient repeats a tongue twister

This helps identify pronunciation difficulties.

92
Q

What should be inspected when the patient opens their mouth during CN XII testing?

A

Deformities or abnormalities

This can indicate issues with tongue function.

93
Q

What is noted when a patient sticks out their tongue during testing of CN XII?

A

Any deviations from straight

A straight tongue indicates normal function.

94
Q

What is the procedure to test for weakness in the tongue during CN XII assessment?

A

Push tongue against inside of cheek while clinician pushes outside

This is done for both cheeks.

95
Q

What are some lesions that affect the cavernous sinus?

A

Arteriovenous fistulas, craniopharyngioma, pituitary tumors, granulomatous inflammation

These lesions can lead to cranial nerve involvement.

96
Q

Which cranial nerve is closely associated with the cavernous sinus lesions?

A

Oculomotor nerve

It is in close proximity to the fourth, sixth, and first division of the fifth cranial nerve.

97
Q

What symptoms might indicate an oculosympathetic migraine in young children?

A

Drooping of the eyelid, double vision, pain, dilated pupil

These symptoms should prompt consideration of an oculosympathetic migraine as a potential diagnosis.

98
Q

True or False: Cranial nerve involvement is uncommon in lesions affecting the cavernous sinus.

A

False

Lesions typically produce additional cranial nerve involvement.

99
Q

Fill in the blank: An oculosympathetic migraine should be considered as a potential diagnosis in young children presenting with _______.

A

drooping of the eyelid, double vision, pain, dilated pupil

100
Q

Most common cause of a pupil-involving third nerve palsy

A

Aneurysm of posterior communicating artery at the junction of the internal carotid

101
Q

What is aberrant regeneration in the context of third cranial nerve palsy?

A

Misdirection of a portion of the third nerve fibers to alternate muscles innervated by the third nerve.

102
Q

Which muscles are controlled by the oculomotor nerve?

A
  • Medial rectus
  • Superior rectus
  • Inferior rectus
  • Inferior oblique
  • Iris dilator muscle
103
Q

What are common signs of aberrant third nerve regeneration?

A
  • Eyelid-gaze dyskinesis
  • Elevation of involved eyelid on downgaze or adduction (pseudo-Graefe sign)
  • Pupil-gaze dyskinesis
  • Constriction of the pupil on downgaze or adduction
104
Q

What are less common signs of aberrant third nerve regeneration?

A
  • Limitation of elevation or depression of the eye
  • Adduction on attempted elevation or depression
  • Absent optokinetic nystagmus response
105
Q

In which patients is aberrancy from acquired third nerve palsies most often observed?

A

Patients recovering from third nerve damage secondary to trauma or compression by an aneurysm.

106
Q

What percentage of congenital third nerve palsy patients may experience aberrant regeneration?

A

Up to 2/3 of these patients.

107
Q

Do ischemic third nerve palsies produce aberrancy?

A

No, ischemic third nerve palsies do not produce aberrancy.

108
Q

What should be performed if aberrant regeneration develops in a patient with suspected ischemic palsy?

A

Immediate neuroimaging must be performed.

109
Q

When can aberrant regeneration occur after a third nerve palsy?

A

Months to years after, but not typically less than 8 weeks after onset.

110
Q

What is the treatment for aberrant regeneration?

A

Monitoring of the underlying condition; strabismus surgery may be considered for significant symptoms.

111
Q

Does aberrant regeneration resolve spontaneously?

A

No, it is a permanent change in the innervation of the muscles.

112
Q

True or false
Ischemic third nerve palsies rarely, if ever produce aberrancy

A

True
*but may occur in congenital or trauma related third nerve palsies