Cranial Nerves: Olfactory, Optic, Oculomotor, Trochlear, Abducent, Vestibulocochlear, Glossopharyngeal, Accessory, and Hypoglossal Flashcards

1
Q

What is the first cranial nerve?

A

the olfactory nerve

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2
Q

The olfactory nerve is made up of what fibers? (non specific)

A

sensory

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3
Q

Where does the olfactory nerve arise from?

A

the olfactory epithelial cells lining the olfactory mucosa that cover the ethmoturbinates and the caudal aspect of the walls of the septum

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4
Q

What nerves take the same route of the olfactory nerve?

A

the terminal nerve and the accessory olfactory nerve

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5
Q

What process does the the accessory olfactory nerve take part in?

A

the phlemen response

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6
Q

What is the accessory olfactory nerve also known as?

A

the vomeronasal nerve

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7
Q

Where does the olfactory nerve terminate at?

A

the olfactory bulb

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8
Q

What does the olfactory nerve pass through to get to its termination point?

A

the cribriform plate

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9
Q

True or False: the olfactory nerve can be seen with the naked eye

A

False: it is microscopic

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10
Q

What is the second cranial nerve?

A

the optic nerve

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11
Q

The optic nerve is made up of what type of fibers (specific and non specific)?

A

sensory - SSA

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12
Q

What is the origin of the optic nerve?

A

the retinal ganglion

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13
Q

What does the optic nerve pass through to get the cranial cavity?

A

the sclera and the optic canal

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14
Q

Where is the optic canal located?

A

within the presphenoid bone

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15
Q

In the dog, what do about 75% of the axons cross over for the optic nerve?

A

they cross over to the opposite side a the optic chiasma and course further as optic tracts on the lateral aspect of the diencephalon part of the brain

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16
Q

What is the third cranial nerve?

A

the oculomotor nerve

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17
Q

The oculomotor nerve is made up of what type of fibers (non specific)?

A

motor

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18
Q

What part of the oculomotor nerve supplies the extrinsic muscles of the eyeball?

A

a ventral motor root (containing GSE fibers)

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19
Q

What does the oculomotor nerve carry to the ocular smooth muscles?

A

parasympathetic general visceral efferent

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20
Q

Where are the neurons of the oculomotor nerve located?

A

in the oculomotor nuclei in the mesencephalon, ventrolateral to the mesencephalon

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21
Q

Through what does the oculomotor nerve exit the cranial cavity?

A

the orbital fissure

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22
Q

What are the two branches of the oculomotor nerve?

A

a small dorsal branch and a large ventral branch

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23
Q

What does the dorsal branch of the oculomotor nerve supply?

A

the dorsal rectus and the levator palpebrae superioris muscles

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24
Q

Where does the ventral branch of the oculomotor nerve course?

A

ventral lateral to the optic nerve

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25
Q

What does the ventral branch of the oculomotor nerve supply?

A

the medial rectus, ventral rectus, and ventral obliques

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26
Q

What does the ventral branch of the oculomotor nerve contain?

A

ciliary ganglion

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27
Q

What do the ciliary ganglion of the oculomotor nerve supply?

A

the ciliary muscle and the sphincter muscle of the iris

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28
Q

What is ptosis?

A

when the levator palpebrae superioris muscle is not able to elevate the upper eyelid and creates a droopy eyelid looking appearance

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29
Q

What is the fourth cranial nerve?

A

the trochlear nerve

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30
Q

The trochlear nerve is made up of what type of fibers (non specific)?

A

motor

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31
Q

What does the trochlear nerve supply?

A

motor innervation to the dorsal oblique muscle of the contralateral side

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32
Q

What do axons on the left side of the brain stem supply?

A

the muscle of the eyeball on the right side

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33
Q

Where is the nucleus of the trochlear nerve located?

A

it surrounds the mesencephalic aqueduct but is caudal to the oculomotor nucleus

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34
Q

Through what does the trochlear nerve go through to exit the cranial cavity?

A

the orbital fissure

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35
Q

What are the special features of the trochlear nerve (3 things)?

A
  • it is the only cranial nerve that arises from the dorsal aspect of the brainstem
  • it is the only nerve that supplies to the muscle of the opposite side
  • it is the smallest cranial nerve and only supplies one muscle
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36
Q

What is the sixth cranial nerve?

A

the abducent nerve

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37
Q

The abducent nerve has what type of fibers (nonspecific)?

A

motor

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38
Q

What does the abducent nerve supply?

A

motor fibers to the lateral rectus and retractor bulbi muscles of the eyeball

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39
Q

Where are the neurons of the abducent nerve located?

A

in the abducent nucleus in the medulla oblongata close to the trapezoid body

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40
Q

What is the course of the abducent nerve before it exits the cranial cavity?

A

they cross the reticular foramen and emerges through the trapezoid, lateral to the pyramid, and courses rostrally adjacent to the stalk of the pituitary gland

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41
Q

The abducent nerve exits the cranial cavity through what?

A

the orbital fissure

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42
Q

When does the abducent nerve innervate its target muscles?

A

after it enters the periorbita

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43
Q

What is the only nerve that does not exit the cranial cavity?

A

the vestibulocochlear nerve

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44
Q

What is the eighth cranial nerve?

A

the vestibulocochlear nerve

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45
Q

What are the roots of the vestibulocochlear nerve?

A

vestibular and cochlear root

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46
Q

Where are the neurons for the vestibular root of the vestibulocochlear nerve located?

A

in the vestibular ganglion within the petrous part of the temporal bone

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47
Q

What do the axons of the vestibular root of the vestibulocochlear nerve innervate?

A

the hair cells in the cristae ampullare and macula utriculi and sacculi of the membranous labyrinth

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48
Q

Where is the cochlear root of the vestibulocochlear nerve located?

A

in the spiral ganglion within the osseous modiolus of the cochlea

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49
Q

What part of the neurons of the chochlear root of the vestibulocochlear nerve synapse with what?

A

the dendritic processes of the neurons synapse with the hair cells of the spiral organ and the cochlear duct

50
Q

What impulses does the cochlear root of the vestibulocochlear nerve transmit?

A

impulses perceived as sound

51
Q

Along with never leaving the skull, what else does the vestibulocochlear nerve not leave?

A

the petrous part of the temporal bone via the internal acoustic meatus

52
Q

Where does the vesstibular root of the vestibulocochlear nerve terminate?

A

in the vestibular nucleus

53
Q

Where does the cochlear root of the vestibulocochlear nerve terminate?

A

in the trochlear nucleus

54
Q

What is the ninth cranial nerve?

A

the glossopharyngeal nerve

55
Q

The glossopharyngeal nerve has what type of nerve fibers (specific)?

A

GVA, SVA, GSE, and GVE fibers

56
Q

What do the GVA fibers of the glossopharyngeal nerve innervate?

A

the caudal 1/3 of the tongue, pharyngeal mucosa, and the carotid sinus

57
Q

What do the SVA fibers of the glossopharyngeal nerve innervate?

A

the taste buds in the foliate and vallate papillae in the caudal 1/3 of the tongue

58
Q

Where do the GSE fibers of the glossopharyngeal nerve originate from?

A

the nucleus ambiguous

59
Q

Where do the GVE fibers of the glossopharyngeal nerve originate from?

A

the neurons located in the parasympathetic nucleus of the glossopharyngeal nerve

60
Q

Where does the glossopharyngeal nerve emerge from?

A

caudal to the vestibulocohlear nerve

61
Q

The glossopharyngeal nerve exits the cranial cavity through what?

A

the jugular foramen in the tympanooccipital fissure

62
Q

What else exits in the same place that the glossopharyngeal nerve exits?

A

the vagus and accessory nerves

63
Q

What does the glossopharyngeal nerve give off once it exits the cranial cavity?

A

the tympanic nerve

64
Q

What type of fibers does the tympanic nerve of the glossopharyngeal nerve have?

A

GVE

65
Q

What type of axons does the tympanic nerve of the glossopharyngeal nerve contain?

A

preganglionic parasympathetic axons

66
Q

The tympanic nerve enters the _____ _____ and forms the _____ _____.

A

tympanic cavity, tympanic plexus

67
Q

What arises from the tympanic plexus?

A

the minor petrosal nerve

68
Q

What does the minor petrosal nerve form?

A

the neurons in the otic ganglion

69
Q

Where is the otic ganglion located?

A

adjacent to the oval foramen

70
Q

What type of axons are in the otic ganglion?

A

postganglionic axons

71
Q

What do the postganglionic axons of the otic ganglion supply?

A

it joins the auriculotemporal nerve and supplies the GSE to the parotid and zygomatic salivary glands

72
Q

Before giving off its terminal branches, where does the glossopharyngeal course?

A

medial to the cranial cervical sympathetic ganglion

73
Q

What are the five terminal branches of the glossopharyngeal nerve?

A

branch to the carotid sinus, sylopharyngeal branch, tonsillar branch, lingual branch, pharyngeal branch

74
Q

What is contained in the branch to the carotid sinus of the glossopharyngeal?

A

it contains baroreceptors in the wall of the carotid bulb and chemoreceptors in the carotid body

75
Q

What type of fibers does the stylopharyngeal branch carry?

A

GSE fibers

76
Q

What does the stylopharyngeal branch of the glossopharyngeal nerve supply?

A

the stylopharyngeus mussle and other pharyngeal muscles along the vagus nerve

77
Q

What does the tonsillar branch of the glossopharyngeal nerve supply?

A

the palatine tonsil

78
Q

What direction does the lingual branch of the glossopharyngeal nerve course?

A

rostroventrally

79
Q

What does the lingual branch of the glossopharyngeal nerve supply?

A

the tongue mucosa, the taste buds in the vallate and foliate papillae, and the gland in the submucosa of the tongue

80
Q

What kind of fibers does the lingual branch of the glossopharyngeal nerve carry to the caudal 1/3 of the tongue mucosa and where are they located?

A

GVA - in the sensory ganglia where it passes between the jugular foramen and tympanooccipital fissure

81
Q

What kind or fibers does the lingual branch of the glossopharyngeal nerve carry to the tastebuds in the vallate and foliate papillae?

A

SVA

82
Q

What type of fibers does the lingual branch of the glossopharyngeal nerve carry to the submucosa of the tongue?

A

GVE fibers

83
Q

What is the course of the pharyngeal nerve of the glossopharyngeal nerve?

A

it joins the pharyngeal branches from the vagus to form the pharyngeal plexus

84
Q

What does the pharyngeal plexus receive branches from aside from the glossopharyngeal nerve?

A

hypoglossal nerve, postganglionic sympathetic axons from the cranial cervical ganglion

85
Q

What do the branches derived from the pharyngeal plexus supply and what type of fibers do they carry?

A

pharyngeal muscles (GSE), pharyngeal mucosa (GSA), and glands in the pharyngeal mucosa

86
Q

What fibers are in charge of the gag reflex?

A

the GSA and GSE fibers (but not all of them)

87
Q

How do the pharyngeal muscles function during the gag reflex?

A

they all contract simultaneously to constrict the laryngopharynx

88
Q

How dooes the hyoglossus, genioglossus, and geniohyoideus function during the gag reflex?

A

they pull the hyoid bone and tongue rostrally

89
Q

What is the eleventh cranial nerve?

A

the accessory nerve

90
Q

The accessory nerve is innervated by what type of fibers (non specific)?

A

motor

91
Q

What are the roots of the accessory nerve?

A

the cranial root and the spinal root

92
Q

Where is the nucleus of the cranial root of the accessory nerve located?

A

in the medulla oblongata

93
Q

Where are the neurons of the spinal root of the accessory nerve located?

A

in the cervical spinal cord segments from C1-C7

94
Q

For the spinal root, where does each spinal root emerge from the spinal cord?

A

laterally from the spinal cord, midway between the dorsal and ventral roots of the cervical spinal nerves

95
Q

How do the spinal roots become part of the accessory nerve?

A

they join together to form the spinal root

96
Q

How does the spinal root of the accessory nerve enter the cranial cavity?

A

the foramen magnum

97
Q

What does the spinal root of the accessory nerve do once it enters the cranial cavity?

A

it joins the cranial root of the accessory nerve

98
Q

What is the accessory nerve attached to and where?

A

the medulla very close to the roots of the glossopharyngeal nerve and the vagus nerves

99
Q

What does the accessory nerve leave the cranial cavity through?

A

the tympanooccipital fissure

100
Q

Once the accessory nerve exits the cranial cavity, what does it do?

A

it divides into the dorsal and ventral branch

101
Q

What is the course of the dorsal branch of the accessory nerve?

A

courses caudally in the neck ventral and then dorsal to the transverse processes of the cervical vertebrae

102
Q

What does the dorsal branch of the acccessory nerve innervate?

A

the trapezius, cleidocervicalis, cleidomastoideus, and omotransversarius

103
Q

What does the ventral branch of the accessory nerve innervate?

A

the cranial part of the sternocephalicus adn the cleidomastoideus in some dogs

104
Q

What is the twelfth cranial nerve?

A

the hypoglossal nerve

105
Q

Thy hypoglossal nerve is innervated by what type of fibers (non specific and specific)?

A

motor - GSE

106
Q

What does the hypoglossal nerve innervate?

A

the intrinsic and extrinsic muscles of the tongue

107
Q

Where are the neurons of the hypoglossal nerve located?

A

in the midline in the floor of the fourth ventricle of the medulla

108
Q

Where do the roots of the hypoglossal nerve emerge?

A

from the medulla oblongata lateral to the pyramid on the ventral surface of the medulla

109
Q

What does the hypoglossal nerve exit through to leave the cranial cavity?

A

the hypoglossal canal

110
Q

How does the hypoglossal nerve course?

A

ventrorostrally lateral to the external carotid artery

111
Q

What happens when the hypoglossal nerve courses ventral to the external carotid artery?

A

it gives off two communicating branches

112
Q

What does the first communicating branches of the hypoglossal nerve go to?

A

to the cervical nerve to form the cervical loop

113
Q

After giving of the communicating branches what is the course of the hypoglossal nerve?

A

it courses ventrally and rostrally, and passes medial to the mandibular salivary gland and cranially it lies close to the lingual artery where it enters the tongue

114
Q

Why does injury to the hypoglossal nerve cause?

A

paralysis to the tongue

115
Q

What is strabismus?

A

injury to the oculomotor, trochlear, and abducent nerves that cause a deviated eye

116
Q

What causes lateral strabismus?

A

injury to the oculomotor nerve

117
Q

What is lateral strabismus?

A

when the muscles cannot pull the eyeball medially and dorsally

118
Q

What causes medial strabismus?

A

injury to the abducent nerve

119
Q

What is medial strabismus?

A

when the muscles of the eye cannot pull the eye latery

120
Q

What does injury to the trochlear nerve cause?

A

the dorsal oblique is not functional do it cannot rotate the eyeball in the other direction

121
Q

What is ptosis?

A

when the levator palpebrae superioris muscle is not able to elevate the upper eyelid

122
Q

What nerve is involved in ptosis?

A

the oculomotor nerve