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Neuroanatomy Exam 2 > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

General peripheral distribution of CN I

A

Olfactory mucosa/olfactory membrane (uppermost part of nasal septum)

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2
Q

Function of CN I

A

Sense of smell (SVA)

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3
Q

Ganglia in CN I?

A

Neurons are NOT found in a ganglion (unique)

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4
Q

Nuclei and connections in CN I (origin, termination, and function)

A

First order axons run from olfactory epithelium, through the cribriform plate, and terminate in the olfactory bulb

Second order neurons run in the olfactory tract, which bifurcates into the medial and lateral olfactory striae and then terminate in the primary olfactory cortex and the amygdala – does NOT project into the thalamus

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5
Q

Pathways of CN I

A

Primary olfactory cortex projects to the hypothalamus, amygdala, memory cortical areas, and olfactory association complex

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6
Q

Olfactory receptor cells

A

First order neurons that are found in the olfactory mucosa, and run through the cribriform plate to form the olfactory nerve; unmyelinated and only nerve cells that are exposed to the environment

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7
Q

Olfactory nerve

A

Composed of olfactory fila (bundles of olfactory receptor cell axons)

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8
Q

Definitions of anosmia, hyposmia, and paraosmia

A

Anosmia – complete loss of sense of smell

Hyposmia – weakened sense of smell

Paraosmia – distorted perception of the sense of smell

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9
Q

General peripheral distribution of CN II

A

Neural retina (rods and cones are receptor cells)

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10
Q

Function of CN II

A

Vision

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11
Q

Nuclei and connections in CN II

A

Rods and cones (bipolar cells)

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12
Q

Tracts of CN II

A

Rods and cones (first order neurons) transmit to ganglion cells (second order neurons), which gather to form the optic nerve; third order neurons arise from the LGN and travel to the primary visual cortex in the occipital lobe

Optic nerve passes through the optic canal to enter the cranial vault, and then converge to form the optic chiasma, which diverges to form the optic tracts

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13
Q

CN II terminates in these 3 places

A
  1. Lateral geniculate nucleus (LGN) of the thalamus
  2. Superior colliculus (head/eye movement reflexes)
  3. Pretectal area (pupillary response) and the hypothalamus
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14
Q

Optic nerve

A

Heavily myelinated, technically tract of the brain and NOT a peripheral nerve

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15
Q

Optic tract

A

Divergence of optic chiasm

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16
Q

Lateral genticulate nucleus (LGN)

A

Nucleus where most optic fibers terminate

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17
Q

Superior colliculus

A

Some optic tract fibers terminate here – reflex head/eye movements

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18
Q

Visual cortex

A

In occipital lobe where third order visual axons terminate

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19
Q

Lesion at optic nerves

A

Loss of any visual information from that eye (total blindness in that eye)

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20
Q

Lesion at angle of optic chiasma

A

Loss of visual information from the nasal side of both eyes (binasal heteronymous hemianopia)

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21
Q

Lesion at optic chiasma

A

Loss of visual information from the temporal side of BOTH EYES (bitemporal heteronymous hemianopia)

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22
Q

Lesion at optic tract

A

Loss of visual information from the nasal side of that eye, and the temporal side of the opposite eye (right or left homonymous hemianopia)

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23
Q

Lesion at upper geniculate nucleus

A

Loss of visual information from the upper, nasal part of that eye and the upper, temporal part of the opposite eye (right or left upper homonymous quadrantanopia)

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24
Q

Lesion at lower geniculate nucleus

A

Loss of visual information from the lower, nasal part of that eye and the lower, temporal part of the opposite eye (right or left lower homonymous quadrantanopia)

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25
Q

General peripheral distribution of CN III

A

Muscles of the eye

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26
Q

Functions of CN III

A

Skeletal motor to levator palpebrae superioris, superior/medial/inferior rectus, and inferior oblique

Parasympathetic to sphincter pupillae and ciliary muscles

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27
Q

Pathways of CN III

A

Pierces the dura mater to enter the cavernous sinus, then through the superior orbital fissure, and disseminates its branches to various muscles after entering the orbit

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28
Q

Nuclei of CN III

A 
Oculomotor nucleus (GSE)
Edinger-Westphal nucleus (GVE)
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29
Q

Oculomotor nucleus and its connections

A

Located ventral to the periaqueductal gray in the rostral midbrain; contains motor neurons whose axons form CN III

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30
Q

Edinger-Westphal nucleus and its connections

A

Contains preganglionic parasympathetic neurons, which join CN III and travel to the orbit, terminating in the ciliary ganglion, which is where they synapse with postganglionic fibers that terminate in the eye bulb via short ciliary nerves of CN V

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31
Q

Damage to CN III causes…

A

Ipsilateral injuries to all muscles of the eye (except SO4LR6), ptosis, deviation of the eye laterally and downward, pupil dilation, diplopia, and inability of lens to accommodate (flat lens)

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32
Q

Horner’s syndrome

A

Ptosis but CONSTRICTION of the pupil (miosis) due to interruption of sympathetic innervation of dilator pupillae muscle – SYMPATHETICS are damaged in this syndrome

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33
Q

General peripheral distribution of CN IV

A

Superior obliques

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34
Q

Function of CN IV

A

Skeletal motor (GSE) to superior oblique muscle

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35
Q

Nucleus of IV and connections

A

Trochlear nucleus (GSE) located at level of inferior colliculus in caudal midbrain – fibers leave nucleus, decussate posteriorly, and exit brainstem just inferior to inferior colliculus

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36
Q

Tracts of CN IV

A

CN IV is unique – nerve arises from the contralateral nucleus, is the ONLY CN that arises from the posterior brainstem, and is the longest/thinnest

Passes into the cavernous sinus and through the superior orbital fissure to get into the orbit

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37
Q

Lesion in CN IV nucleus

A

Paralysis of contralateral SO

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38
Q

Lesion in CN IV nerve

A

Paralysis of ipsilateral SO

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39
Q

Details about lesions in CN IV

A

Since the inferior rectus also pulls the eye inferiorly, the patient’s ability to look down is not eliminated, just weakened; hyperopia does occur at rest

When looking at a book or walking down a flight of stairs, the IR muscle extorts the eye (since it is unopposed), which causes vertical diplopia – counteraction is possible by tilting the head to the normal side (normal eye rotates inward, which aligns it with the affected/extorted eye) and pointing chin downward, which causes the normal eye to roll upward, and compensate for the hypertropia

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40
Q

General peripheral distribution of CN V

A

Face, muscles of mastication

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41
Q

CN V carries parasympathetics from…

A

ONLY one to carry parasympathetic “hitchhikers” of other CNs

Oculomotor – fibers leave the ciliary ganglion via the ophthalmic division to terminate in the sphincter pupillae and ciliary muscles

Facial – fibers leave the pterygopalatine ganglion via the maxillary division to terminate in the lacrimal, nasal, and palatine glands; fibers leave the submandibular ganglion via the mandibular division to terminate in the sublingual and submandibular glands

Glossopharyngeal – fibers leave the otic ganglion via the mandibular division to terminate in the parotid gland

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42
Q

CN V carries sympathetics from…

A

Internal carotid plexus

Ophthalmic division to dilator pupillae muscle

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43
Q

Functions of CN V

A

General sensation (GSA) – scalp, cranial dura, face, cornea, mucous membranes

General proprioception (GP) – extraocular muscles, TMJ, muscles of mastication

Skeletal motor (SVE) – muscles of mastication, mylohyoid, anterior digastric, tensor tympani, tensor veli palatini, and the pterygoids

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44
Q

Ganglia of CN V

A

Trigeminal ganglion – sensory, pseudounipolar neurons, no synapses

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45
Q

Nuclei of CN V

A

Sensory nuclei: mesencephalic (in midbrain), principal (in mid-pons), spinal (in pons, medulla, and C1-C2)

Motor nuclei: cell bodies of neurons whose axons form CN V motor root (joints mandibular branch of CN V)

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46
Q

Mesencephalic nucleus (CN V)

A

General proprioception from CN V muscles

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47
Q

Principal nucleus (CN V)

A

Discriminatory (fine, detailed) touch and pressure from orofacial structures, proprioception from extraocular muscles and TMJ

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48
Q

Spinal nucleus (CN V)

A

Nociceptive and thermal sensation, and some tactile, from the orofacial structures (ONLY CN with “pain nucleus”)

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49
Q

Tracts of CN V

A

Spinal
Ventral trigeminal lemniscus
Dorsal trigeminal lemniscus
Trigeminoreticular fibers

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50
Q

Spinal tract (CN V)

A

From pons (near sensory root of CNV), descends through medulla to C1-C2, terminates in the spinal nucleus of CNV, and responsible for pain and temperature

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51
Q

Ventral trigeminal lemniscus (CN V)

A

From spinal nucleus of CNV, ascends to thalamus, terminates in the VPM nucleus, and responsible for pain and temperature

52
Q

Dorsal trigeminal lemniscus (CN V)

A

From principal nucleus of CNV, ascends to thalamus, terminates in the VPM nucleus, and responsible for discriminative touch

53
Q

Trigeminoreticular fibers

A

From principal nucleus of CNV, projects near RF of brainstem, terminates in the RF, responsible for arousal (“smelling salts”)

54
Q

Pathway of ophthalmic division (CN V1)

A

Travels through the cavernous sinus and exits via the superior orbital fissure to its zone of innervation

55
Q

Pathway of maxillary division (CN V2)

A

Travels through the cavernous sinus and exits via the foramen rotundum to its zone of innervation

56
Q

Pathway of mandibular division (CN V3)

A

Travels through the foramen ovale

57
Q

Pathway for discriminatory touch and pressure (CN V)

A

1st order neurons from the trigeminal ganglion, terminate in the principal nucleus of CNV –> 2nd order neurons join the dorsal trigeminal lemniscus and ascend to the VPM nucleus –> 3rd order neurons, which project into the postcentral gyrus

58
Q

Pathway for pain and temperature (CN V)

A

1st order neurons from trigeminal ganglion, terminate in the spinal nucleus of CNV –> 2nd order neurons join ventral trigeminal lemniscus to ascend to VPM nucleus –> 3rd order neurons project into the postcentral gyrus, anterior cingulate, and anterior insular cortices

59
Q

Motor pathway for CN V

A

LMNs in motor nucleus of CN V, axons exit brainstem at mid-pons level and join mandibular division and distribute to all innervated muscles

60
Q

Pathway for general proprioception (CN V)

A

1st order neurons from the mesencephalic nucleus (pseudounipolar, NOT multipolar) distribute their peripheral processes with branches of CNV, and their central processes terminate in the main sensory nucleus of CNV (sensation) and the motor nucleus of CNV (jaw movement)

61
Q

Lesions in CN V would produce what deficits (based on divisions)?

A

Ophthalmic – reduce sensation over the V1 zone, inhibit corneal blink reflex

Maxillary – reduce or inhibit sensation over the V2 zone

Mandibular – reduce or inhibit sensation over the V3 zone, may cause paralysis to the muscles of mastication (jaw deviation to side of lesion)

62
Q

Trigeminal neuralgia

A

Sharp, intermittent pain on one side of the face that exhibits spontaneous onset; each attack only last a few seconds, and is triggered by touching the face, brushing teeth, moving jaw while chewing; can be caused by DEMYELINATION of CN V (as it enters the pons of the brainstem –> demyelinating disease OR
vascular structures called “loops” may develop and compress CN V, causing demyelination) which can cause ephaptic transmission of nerve impulses between adjacent fibers

63
Q

General peripheral distribution of CN VI

A

Lateral rectus

64
Q

Function of CN VI

A

Skeletal motor (GSE) to LR muscle (abduction of the eye)

65
Q

Nucleus of CN VI and connections

A

Abducens nucleus’ (located in caudal pons) cell bodies give axons that gather to form CNVI; also contains cell bodies of internuclear neurons whose axons cross the midline to join the MLF, which ascends to the oculomotor nucleus (rostral midbrain) and terminate specifically to the LMNs that innervate the medial rectus muscle

66
Q

Pathways of CN VI

A

Passes through cavernous sinus and superior orbital fissure

67
Q

Lesion on LMNs of CN VI

A

Ipsilateral LR is paralyzed, causing medial deviation (esotropia/medial strabismus, horizontal diplopia) – compensate by turning head towards the side of the lesion to cause opposite eye to look laterally

68
Q

Lesion on abducens nucleus of CN VI

A

Same effect as the nerve; also prevents the contralateral eye from adducting (unique – ONLY CN where a lesion to the nerve and the nucleus don’t have the exact same effect)

69
Q

Lesion on MLF of CN VI

A

This connects the abducens nuclei to the contralateral oculomotor nuclei, which damage is only evident during conjugate horizontal movement (INO); vergence occurs normally

If the right MLF is damaged, the result is a disconnect between the left abducens and right oculomotor nuclei, so the left eye will abduct with nystagmus but the right eye will NOT adduct during left lateral drift

70
Q

One and a half syndrome

A

Lesion in the vicinity of the abducens nucleus that involves:

1 = Entire abducens nucleus of one side, which includes LMNs to the LR and interneurons to the contralateral oculomotor nucleus (ipsilateral lateral gaze paralysis when looking to the side of the lesion)

AND

1/2 = the ipsilateral MLF fibers arising from the contralateral abducens nucleus (causes INO when looking away from the side of the lesion)

So, 1½ syndrome is ipsilateral lateral gaze paralysis and INO – the ipsilateral eye has no horizontal movement (medially deviated) AND the opposite eye can only abduct with nystagmus

71
Q

General peripheral distribution of CN VII

A

Face, neck, mouth

72
Q

Functions of CN VII

A

Motor (SVE) to muscles of facial expression, platysma, posterior digastric, stylohyoid, stapedius, auricularis, and occipitalis

Taste (SVA) from anterior 2/3 of tongue

Parasympathetic (GVE) to lacrimal, nasal, palatine, submandibular, and sublingual glands

General sensation (GSA) from skin in posterior ear, pinna, and external auditory meatus

Visceral sensation (GVA) from nasal cavity, soft palate, pharyngeal wall

73
Q

Ganglia of CN VII

A

Geniculate (sensory)
Pterygopalatine (parasympathetic)
Submandibular (parasympathetic)

74
Q

Geniculate ganglion of CN VII

A

Pseudounipolar neurons (GVA, SVA, GSA); no synapses

75
Q

Pterygopalatine ganglion of CN VII

A

Postganglionic parasympathetic neurons (GVE); axons terminate in the lacrimal glands, nasal mucous membrane, and palatine salivary glands; called the “hay fever ganglion”

76
Q

Submandibular ganglion of CN VII

A

Postganglionic parasympathetic neurons (GVE); axons terminate in the submandibular and sublingual glands

77
Q

Nuclei of CN VII

A

Facial – cell bodies of LMNs (upper half – receives bilateral corticonuclear projections or UMNs; lower half – receives ONLY contralateral corticonuclear projections)

Superior salivatory – cell bodies of preganglionic parasympathetic neurons –> connects to the pterygopalatine or submandibular gland

Solitary – also contains fibers from CNIX and CNX; receives central processes of taste sensation (SVA) and GVA neurons

78
Q

Tracts of CN VII

A

Solitary and spinal (from CN V)

79
Q

Solitary tract (CN VII)

A

Carries central processes of SVA and GVA neurons to the solitary nucleus, which processes taste sensation; projects into the hypothalamus, which mediates visceral response to unpleasant sensation

80
Q

Spinal tract (of CN V, acts for CN VII)

A

Nociception from CN VII, CNIX, and CN X all travel along the spinal tract of CN V and carry nociceptive stimuli to the pain nucleus of CN V

81
Q

Corneal blink reflex – afferent limb (CN VII)

A

Sensory, from ophthalmic division of CN V

82
Q

Lesion in afferent limb of CN VII

A

The eye ipsilateral to the lesion will not be able to send sensory information to the CN V nuclei, so neither eye will blink; however, if you stimulate the other eye, both eyes will blink

83
Q

Corneal blink reflex – efferent limb (CN VII)

A

Motor, from CN VII to the orbicularis oculi

84
Q

Lesion in efferent limb of CN VII

A

Orbicularis oculi on the ipsilateral side will be weakened or paralyzed, however the sensory information will not be inhibited on either side, therefore stimulation of either eye will cause ONLY the unaffected eye (contralateral to the lesion) to blink

85
Q

Pupillary light reflex

A

Afferent comes from CN II and efferent from CN III – DIFFERENT than corneal blink reflex

86
Q

Lesions in facial canal (LMN) will cause…

A

Dry eyes (due to greater petrosal nerve, GVE)
Hyperacusis (due to nerve to the stapedius, SVE)
Pain behind ear (due to geniculate ganglion, GSA)
Loss of taste on anterior 2/3 of tongue (due to chorda tympani nerve, SVA)

87
Q

UMN lesion to facial nerve

A

Patient will not experience dry eyes, pain behind the ear, hyperacusis, or taste deficits; there will be weakness or paralysis in the lower half of the contralateral face, due to lack of ipsilateral projections

88
Q

Bell’s palsy

A

LMN lesion (distal to the facial canal) that causes total paralysis on the ipsilateral half of the face

Idiopathic, but two different presentations:

  1. Neuropraxia – demyelination conduction block; nerve cell axons are not lost, so recovery is quick and complete
  2. Axonal damage with Wallerian degeneration – nerve cell axons are lost; recovery is slow and incomplete
89
Q

General peripheral distribution of cochlear part of CN VIII

A

Ears

90
Q

Function of cochlear part of CN VIII

A

Hearing (SSA)

91
Q

Ganglia of cochlear part of CN VIII

A

Spiral, which contains bipolar sensory neurons; no synapses

92
Q

Pathways of cochlear part of CN VIII – first order neurons

A

First order cell bodies in the cochlear ganglion; peripheral processes terminate in receptor hair cells of the organ of Corti; central processes form the root of the nerve, which enters the pons and bifurcates, then synapses in the dorsal and ventral cochlear nuclei

93
Q

Pathways of cochlear part of CN VIII – second order neurons

A

IPSILATERAL EAR

Axons from the ventral cochlear nucleus form the ventral acoustic stria (trapezoid body), which terminates in a nucleus of the trapezoid body and the superior olivary nucleus; other fibers travel to the LL and inferior colliculus:

Axons from the dorsal cochlear nucleus form the dorsal acoustic stria, ascend into the LL, and terminate in the inferior colliculus

94
Q

Pathways of cochlear part of CN VIII – third order neurons

A

BOTH EARS

Housed in the superior olivary nuclei and are involved with the localization of sound

95
Q

Main relay for hearing in midbrain and where it projects

A

Inferior colliculus, projects into medial geniculate nucleus

96
Q

Main relay for hearing in the thalamus and gives rise to what?

A

Medial geniculate nucleus (processes sound intensity and frequency), gives rise to auditory radiation, which projects into primary auditory cortex

97
Q

Sound attenuation reflex (cochlear part of CN VIII)

A

Tensor tympani and stapedius contract to dampen input

98
Q

Conduction vs. sensorineural deafness

A

Conduction – blockage (wax), tympanosclerosis, or ruptured eardrum, etc.

Sensorineural – damage to the hair cells or cochlear nerve, etc.

99
Q

General peripheral distribution of vestibular part of CN VIII

A

Semicircular canals

100
Q

Function of vestibular part CN VIII

A

Equilibrium/balance (SSA)

101
Q

Ganglia of vestibular part of CN VIII

A

Vestibular, which contains bipolar sensory neurons; no synapses

102
Q

Pathways of vestibular part of CN VIII – first order neurons

A

First order neuron cell bodies are in the vestibular ganglion; peripheral processes terminate in the receptor hair cells of the maculae of the utricle, saccule, and the cristae of the semicircular canal ampullae; central processes form the nerve, travel to the pons, bifurcate, and synapse in the vestibular nuclei (some pass into the inferior cerebellar peduncle to end in the ipsilateral flocculonodular lobe of the cerebellum)

103
Q

Pathways of vestibular part of CN VIII – second order neurons

A

Second order neurons give off axons that join the MLF to project to the extraocular muscle nuclei, RF, and cervical spinal cord; other fibers terminate in the cerebellum and thalamus

104
Q

Pathways of vestibular part of CN VIII – third order neurons

A

Third order neurons are found in the VPL and VPI nuclei of the thalamus and project into the primary vestibular cortex

105
Q

General peripheral distribution of CN IX

A

Pharynx and mouth

106
Q

Functions of CN IX

A

Sensory (GVA) from pharyngeal tube, palatine tonsils, fauces, pharynx, and carotid sinus

Sensory (GSA) from the ear, ear canal, and posterior 1/3 of tongue

Taste (SVA) from posterior 1/3 of tongue

Parasympathetic (GVE) to parotid gland and salivary glands in tongue and pharynx

Motor (SVE) to the stylopharyngeus muscle

107
Q

Sensory ganglia of CN IX

A

Superior – pseudounipolar (GSA); central processes descend in the spinal tract of CNV to spinal V nucleus (nociception)

Inferior – pseudounipolar (GVA, SVA); central processes join the solitary tract to terminate in the solitary nucleus

108
Q

Parasympathetic ganglion of CN IX

A

Otic – postganglionic parasympathetic neurons –> parotid gland

109
Q

Nuclei of CN IX and their connections

A

Inferior salivary – contains the cell bodies of preganglionic parasympathetic neurons (GVE), whose axons terminate in the otic ganglion

Nucleus ambiguus – contains cell bodies of motor neurons (SVE)

Solitary nucleus – receives central processes of GVA and SVA neurons

110
Q

Lesion at CN IX would cause…

A

Loss of taste (posterior 1/3 tongue), decrease in salivary secretion, diminished visceral sensation, and loss of gag/carotid sinus reflexes

111
Q

Gag reflex

A

Sensory input from CN IX, motor response from CN X

112
Q

General peripheral distribution of CN X

A

Pharynx/larynx, thorax, abdomen

113
Q

Functions of CN X

A

Parasympathetic (GVE) to the thoracic and abdominal viscera

Skeletal motor (SVE) to most of pharyngeal and laryngeal skeletal muscles

Taste (SVA) from epiglottis, soft palate, and upper pharynx

Sensory (GSA) from outer ear, external auditory meatus, and posterior 1/3 of the dura mater

Sensory (GVA) from the mucous membrane of the soft palate, pharynx, esophagus, larynx, trachea, and carotid body

114
Q

Ganglia of CN X

A

Superior – sensory pseudounipolar (GSA); no synapses; central processes descend in the spinal V tract (nociception)

Inferior – sensory pseudounipolar (GVA and SVA); no synapses; central processes join the solitary tract

Parasympathetic – thoracic/abdominal viscera; innervate cardiac muscle and smooth muscle/glands of the heart, respiratory tract, and GI tract

115
Q

Nuclei of CN X and their connections

A

Dorsal motor – parasympathetic (visceral motor) and preganglionic parasympathetic neurons

Nucleus ambiguus – skeletal motor (larynx and pharynx)

Solitary – receives the central processes of the taste (SVA) and visceral sensory (GVA) neurons; fibers from CN VII, CN IX, and CN X terminate here

116
Q

Lesion in CN X – unilateral

A

Flaccid paralysis of pharynx, larynx, and sfot palate, dyspnea, loss of gag reflex, loss of general sensation, and cardiac arrhythmias

117
Q

Lesion in CN X – bilateral

A

Death

118
Q

General peripheral distribution of CN XI

A

Laryngeal muscles, SCMs, and trapezii

119
Q

Function of CN XI

A

Innervate laryngeal muscles, SCMs, and trapezii (SVE/GSE) and general proprioception from SCMs and trapezii

120
Q

Tracts of CN XI

A

Nerve fibers arise between dorsal and ventral roots at levels C1-C5, maybe C6, run through the foramen magnum and meet with aberrant vagal fibers; the aberrant vagal fibers will separate and join the main root of the vagus nerve, while the spinal fibers will continue as CNXI; travels through the posterior cervical triangle and innervates the SCM and trapezius

121
Q

Deficits following CN XI lesion

A

Winging of the scapula, most prominent during abduction of the arm on the affected side

122
Q

General peripheral distribution of CN XII

A

Tongue

123
Q

Function of CN XII

A

Skeletal motor to intrinsic muscles and most extrinsic muscles of the tongue; mediates tongue movement

124
Q

Ganglion of CN XII

A

Hypoglossal nucleus (medulla), gives rise to fibers that emerge between the pyramids and the olives, then gather together to form CN XII and project to the tongue

125
Q

Deficits following lesion in LMN of CN XII

A

Ipsilateral hemiparalysis, ipsilateral tongue atrophy, fasciculations, furrowing, tongue deviation to the side of the lesion

126
Q

Deficits following bilateral CN XII deficit

A

Difficulty speaking and eating

Neuroanatomy Exam 2 (4 decks)

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