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Anatomy Test 3 > Lect 8 Cranial Nerves > Flashcards

Lect 8 Cranial Nerves Flashcards

1
Q

CN originating in telecephalon

A

I

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2
Q

CN originating in Diencephalon

A

II

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3
Q

CN originating in the midbrain

A

III,IV

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4
Q

CN originating in the pons

A

V,VI,VII,VIII

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5
Q

CN originating in the pons

A

IX,X,XI,XII

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6
Q

What is carried in a cranial nerve

A

several different types of fibers

  • cutaneous sensory fibers from the skin
  • fibers from special senses (taste)
  • motor fibers to skeletal muscles
  • motor fibers to blands

fiber types within cranial nerves are considered the functional components of these nerves and are commonly referred to as neural modalites

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7
Q

Cranial nerve modalities initials

A

1st initial: Special vs General
2nd initial: Visceral vs somatic
3rd initial: Afferent vs Efferent

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8
Q

Special vs General modality CN

A

Special: function found only in a cranial nerve
General: function may be found in a cranial or spinal nerve

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9
Q

CN modality Visceral vs somatic

A

2nd initial
Visceral: target is part of the visceral system (organ, gland, smooth muscle) OR a structure derived from the specialized embryonic precursors called pharyngeal arches

Somatic: the somatic motor system is under voluntary motor control; somatic sensory fibers carry information from body areas such as skin, muscles, joints

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10
Q

CN modality Afferent vs Efferent

A

Afferent: axon is relaying sensory info to CNS
Efferent: the axon is relaying motor info away from the CNS

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11
Q

Afferent Fiber Types/Neural modalities

A

General somatic afferent (GSA)
General visceral Afferent
Special Afferent

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12
Q

GSA

A

general somatic afferent - convey sensations from skin, muscles, joints

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13
Q

GVA

A

general visceral afferent - convey sensations from internal organs

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14
Q

SA

A

special afferent - serve special senses of vision, hearing, balanc, taste, smell

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15
Q

Efferent fiber types

A

GSE
SVE
GVE

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16
Q

GSE

A

general somatic eff.

innervated striated muscle NOT derived from embryonix pharyngeal arches

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17
Q

SVE

A

innervated striated muscle with embryological origin from the pharyngeal arches (facial expression, mastication muscles)

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18
Q

GVE

A

general visceral efferent

autonomic fibers that innervates smooth muscle and glands (parotid gland, submandibular gland)

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19
Q

SA only CNs

A

I,II,VIII

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20
Q

SVE only CNs

A

XI

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21
Q

GSE only CNs

A

IV,VI,XII

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22
Q

GSE,GVE only

A

CN III

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23
Q

GSA, SVE only CNs

A

CN V

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24
Q

SVE, GVE, GSA, GVA, SA Cranial nerves

A

CN VII, IX, X

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25
Q

Trigeminal Nerve

A 
CN V    GSA, SVE
3 divisions emerge from the trigeminal ganglion
V1- opthalmic nerve 
V2 - Maxillary Nerve
V3- Mandibular Nerve

All carry sensory info, V3 also has a motor component

four brainstem nuclei receive (3) sensory info or project (1) axons - form trigeminal nerve

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26
Q

other terms for trigeminal ganglion

A

semilunar ganglion

gasserian ganglion

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27
Q

GSA of CN V

A

3 divisions of sensory nuclei

  1. Spinal trigeminal nucleus
  2. Main sensory nucleus
  3. Mesencephalic nucleus
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28
Q

Spinal trigeminal nucleus

A

GSA

receives pain, temperature and non discriminitive/crude touch sensations from the face

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29
Q

Main sensory nucleus

A

GSA: receives light touch and pressure info from the face, also proprioceptive info

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30
Q

Mesencephalic nucleus

A

GSA

associated with proprioceptive afferents from the face (displaced ganglion)

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31
Q

SVE of CN V

A

motor nucleus

projects axons to the muscles of mastication (temporalis, masseter, medial, pterygoid, lateral pterygoid) and others

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32
Q

Course of trigeminal nerve

A

emerges from the brainstem, courses anteriorly through middle cranial fossa

  • from trigeminal ganglion located on the flood of the middle cranial fossa, emerge V1,2,3
  • these leave the cranial cavity via openings in the middle cranial fossa
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33
Q

V1 travels through…

A

the superior orbital fissure

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34
Q

V2 travels through…

A

the foramen rotundum

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35
Q

V3 travels through

A

the foramen ovale

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36
Q

Sensory distribution of V1

A 
Supraorbital
Supratrochlear
Infratrochlear
External nasal
Lacrimal
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37
Q

Supraorbital distribution to the skin

A

mucosa of frontal sinus
skin and conjuctiva of middle superior eyelid
skin and pericranium of anterolateral forehead and scalp to vertex

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38
Q

Supratrochlear distribution to the skin

A

Skin and conjunctive of medial aspect of superior eyelid

skin and pericranium of anteromedial forehead

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39
Q

Lacrimal distribution to the skin

A 
lacrimal gland (secretomotor fibers)
-small area of skin and conjunctiva of lateral part of superior eyelid
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40
Q

Infratrochlear distribution to the skin

A

Skin lateral to root of nos

-skin and conjunctiva of eyelids adjacent to medial canthus, lacrimal sac and lacrimal caruncle

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41
Q

External nasal distribution to skin

A

skin of nasal ala, vestibule and dorsum of nose, including apex

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42
Q

V2 terminal branches

A

infraorbital
zygomaticofacial
zygomaticotemporal

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43
Q

infraorbital distribution to skin

A

mucosa of maxillary sinus

  • premolar canine and incisor teeth
  • skin and conjunctiva of inferior eyelid, skin of cheek, lateral nose and anterioinferior nasal septum, skin and oral mucosa of superior lip
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44
Q

zygomaticofacial distribution to skin

A

prominence of cheek

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45
Q

zygomaticotemporal distribution to skin

A

hairless skin anterior part of temporal fossa

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46
Q

V3 terminal branches

A

auriculotemporal
buccal
mental

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47
Q

auriculotemporal distribution to skin

A

skin anterior to auricle and posterior two thirds of temporal region

  • skin of tragus and adjacent helix of auricle
  • skin of roof of external acoustic meatus
  • skin of superior tympanic membrane
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48
Q

buccal distribution to skin

A

skin and oral mucosa of cheek
buccal gingivae
adjacent second and third molars

49
Q

mental distribution to skin

A

chin and skin

oral mucosa of inferior lip

50
Q

Spinal trigeminal system pathway

A

Trigeminal nerve and ganglia receive face pain, temp and crude touch from A delta and c fibers

Passes through spinal trigeminal tract to spinal trigeminal nucleus
-both tract and nucleus extend from mid pons into the rostral spinal cord (C3) where they are continuous with the substantia gelatinosa and Lissauer’s tract

2nd order fibers cross to join spinothalamic tract - called trigeminothlamic tract - synapse on VPM/ILN

51
Q

Organization of spinal trigeminal nucleus

A

(rostral to caudal)
Pars oralis - extends from main sensory nucleus to pontomedullary junction
Pars interpolaris - extends from pontomedullary junction to level of obex
Pars caudalis - nucleus extends from obex to spinal cord (C2-C3)

52
Q

obex

A

marks caudal end of fourth ventricle

53
Q

Pars caudalis function and organization

A

Thought to be major synaptic site for pain, temp and crude touch from the face

  • represents onion pattern for facial distribution
  • more rostrally located nerve endings come from intraoral zones
  • further down the caudalis moves more caudal on the head

responsible for organization

54
Q

Spinal trigeminal tract and spinal trigeminal nucles organization

A

have a ventral to dorsal organization
V1 - located ventrally
V2- located in middle
V3- located dorsally

55
Q

Main sensory and mesencephalic nucleus pathway

A

GSA
no synapse in Mesencephalic nucleus, cell body of pseudounpolar neuron
-A-beta fibers synapse from both tracts on the main sensory nucleus
- 2nd order fibers join the medial lemniscus in the mid-pons - called trigeminal lemniscus

56
Q

2nd order neurons that reveive A-beta info from oral cavity

A

remain uncrossed
travel in dorsal trigeminal tract, located in the dorsomedial brainstem tegmentum (not in the medial lemniscus)
travel ipsilaterally

57
Q

3 regions of the main sensory nucleus of CN V

A

Ventral: receives V1 - to contralateral VPM
mid region: receives V2 - Contralateral VPM
Dorsal: receives V3 - to ipsilateral VPN and contralateral VPM (intraoral regions)***

58
Q

Wallenberg’s syndrome

A

aka lateral medullary syndrome
caused by ischemia in the territory of the vertebral artery or PICA

involves spinal trigeminal nucleus and tract, spinothalamic tract, descending sympathetic fibers

59
Q

Clinical features of Wallenberg’s syndrome

A

issues w/ trigeminal nucleus and tract - ipsilateral facial decreased pain and temp sense

issues w/ spinothalamic tract- contralateral body decreased pain and temp sense

60
Q

A lesion in the left lateral medulla will cause..

A

decrease pain and temp sensation of

  • ipsilateral face (left) (2nd order damage of spinal trigeminal nucleus/tract)
  • contralateral (right) UE, LE and trunk 2nd order damage of the spinothalamic tract
61
Q

Horners syndrome

A 
includes the absence of sympathetically stimulated functions on the ipsilateral side of the head
includes:
ptosis: drooping superior eyelid
miosis: constriction of pupil
anhydrosis: absence of sweating
Redness of skin
62
Q

Sensory information from the trigeminal nerve travels…

A

through the posterior limb of internal capsule to reach postcentral gyrus (laterally) this region (perioral region) has highest density of innervation, largest section

63
Q

Mesencephalic pathway projections

A

Central projections include

  1. Main sensory Nucleus V, follows S-1 pathway
  2. Spinal trigeminal nucleus - > cerebellum; used to modulate motor output (mastication)
  3. Reticular formation mediates reflexes
  4. Motor nucleus V - mediates jaw jerk reflex

most proprioceptive infor from the face is carried by primary afferent axons with the soma in the mesencephalic nucleus

64
Q

CN V motor nerves of V3

A

Soma of alpha beta fibers in mesencephalic nucleus, synapses on motor nucleus
this synapses in the mouth

jaw jerk reflex - tap to middle of chin with the mouth slightly open

also receives input from precentral gyrus -motor nucleus receives bilateral input from corticobulbar tract fibers

65
Q

will a unilateral lesion of corticobulbar tract fibers produce dramitic weakness of mastication?

A

no - CN V motor nucleus receives bilateral input from corticobulbar tract fibers

66
Q

Facial nerve

A

CN VII
Emerges from the brainstem at the ventrolateral aspect of the caudal pons, near the pontomedullary junction
at this point, it has a large motor root (SVE) and smaller root called the nervus intermedius

67
Q

nervus intermedius

A

GSA, SA, GVE, GVA

lies between the motor root of CN VII and CN VIII

68
Q

Facial nerve (CN VII) path

A

emerges from brainstem and into the posterior cranial fossa
It leave the posterior cranial fossa via the internal acoustic meatus
-it then courses through the temporal bone for a distance, an exits the cranium via the styolmastoid foramen

69
Q

internal acoustic meatus

A

where the CN VII leaves the posterior cranial fossa

CN VIII also courses through this

70
Q

styolmastoid foramen

A

where the facial nerve leaves the cranium

71
Q

Functional components of Facial nerve

A 
SVE
GVE
GSA
SA
GVA
72
Q

SVE of facial nerve

A

muscles of facial expression

73
Q

GVE of facial nerve

A

Parasympathetic innervation to the following glands: lacrimal, nasal, palantine, upper pharynx, submandibular and sublingual

74
Q

GSA of facial nerve

A

sensory from a portion of the external ear

75
Q

SA of facial nerve

A

taste from the anterior 2/3 of the tongue and palate

76
Q

GVA of the facial nerve

A

Recurrent fiber path that follows the GVE fibers

77
Q

Facial CN VII SVE pathway

A

Draw - corticobulbar fibers from motor cortex descend to facial motor nucleus in the pons, ipsilaterally to rostral pons and contralaterally to mid & caudal pons

78
Q

Right corticobulbar damage to upper motor neurons of CN VII

A

Selective weakness of LEFT lower facial muscles
would not be able to lift left lip but could raise eyebrows symmetrically

lesion to left corticobulbar fiber would be vice versa

79
Q

lesion to right Facial nerve

A

will result in right upper and lower facial muscle weakness

80
Q

orbicularis oculi

A

closes the eye

81
Q

connections involved in the blink reflex

A

CN V (GSA) - comprise afferent component; carry pain info from cornea into CNS (spinal trigeminal nucleus)

CN VII (SVE) - efferent component of reflex and responsible for closing the eyes

bilateral. spinal trigeminal fibers relay through the reticular formation to bilateral facial motor nuclei

82
Q

CN III, IV, VII

A

oculomoter, trochlear, abducens (respectively)

innervate skeletal muscle that controls eye movements

83
Q

CN III, IV, VII process

A

emerge from the cranial cavity via the superior orbial fissure in the following order: III, IV, VI…then CN V1

84
Q

Innervation of the extraocular eye muscles

A

6 extraocular eye muscles responsible for movement of the globe/eyeball

  • CN III innervates 4 extraocular eye muscles
  • CN IV innervates 1
  • CN VI innervates 1
85
Q

Extraocular eye muscles innervated by CN III

A

Superior rectus
inferior rectus
medial rectus
inferior oblique

also innervates muscle that elevates the eyelid - ;levator palpebrae superioris

86
Q

Extraocular eye muscles innervated by CN IV

A

superior oblique

87
Q

Extraocular eye muscles innervated by CN VI

A

Lateral rectus

88
Q

Abduction of eyeball

A

away from midline

89
Q

adduction of eyeball

A

toward the midline

90
Q

internal/medial rotation/intorsion

A

12 oclock position moves toward the nose

91
Q

external/lateral rotation/extorsion

A

12 oclock position moves away from the nose

92
Q

relative orientation of eyeball

A

visual axis is set off from the orbital axis by about 23 degrees

attachment of extraocular muscles and their relationship to the visual axis impacts the motion each muscle has on eye movement

93
Q

Direction of pull of the extraocular eye muscles if they were to contract in isolation…superior oblique

A

abducts, depresses and medially rotates the eye

attaches posterior and superior to horizontal axis, passes medial to vertical axis and attaches to posterior superior aspect

94
Q

Direction of pull of the extraocular eye muscles …

if they were to contract in isolation inferior oblique

A

abducts, elevates and laterally rotates eye

attaches posterior and inferior to the horizontal axis
passes medial to vertical axis and attaches to posterior inferior aspect of globe

95
Q

Direction of pull of the extraocular eye muscles if they were to contract in isolation superior rectus

A

elevates, adducts and rotates eyeball medially

attaches anterior and superior to horizontal axis
passes medial to vertical axis and attaches to the anterior aspect of globe

96
Q

Direction of pull of the extraocular eye muscles if they were to contract in isolation inferior rectus

A

depresses, adducts and rotates eyeball laterally

attaches anterior and inferior to horizontal axis
passes medial to vertical axis and attaches to the anterior aspect of the globe

97
Q

Direction of pull of the extraocular eye muscles if they were to contract in isolation medial rectus

A

adducts eyeball

98
Q

Direction of pull of the extraocular eye muscles if they were to contract in isolation lateral rectus

A

abducts eyeball

99
Q

Intorsion of the globe

A

muscles with a medial pull above the visual axis mediall rotate (intort) – superior oblique and rectus

100
Q

Extorsion of globe

A

muscles with a medial pull below the visiual axis extort/laterally rotate the globe (inferior oblique and rectus)

101
Q

CN III overview of innervation

A

GSE - superior rectus, inferior rectus, medial rectus, inferior oblique

palpebrae superioris muscle (superior eyelid)

contains parasympathetic fibers GVE that pass to the constrictor muscle of the pupil

102
Q

cranial nerve III nucleus location and path

A

lies in the rostral midbrain at the level of superior colliculus (SC)
oculomotor nerve traverses the superior orbital fissure

neurons in the left oculomotor nucleus project axons that cross midline in the midbrain and contribute fibers to the right oculomotor nerve, and innervate the right superior rectus muscle

103
Q

the oculomotor nerve traverses the

A

superior orbital fissure

104
Q

the levator palpebrae superioris muscle is innervated by…

A

both the right and left axons from the oculomotor nuclei

105
Q

Parasympathetic GVE fibers of CN III

A

Preganglionic para fibers originate in the Edinger-Westphal nucleus

  • axons trabel to ciliary ganglion and synapse on
  • postganglionic para fibers that pass to the ciliary muscles and sphincter pupillae

travel in same tract as other fibers

106
Q

Note about cN III GSE and GVE

A

innervated by the sympathetic nervous system, the preGG cell are located in the lateral horn of the spinal cord and the postGG cell bodies are located in the sympathetic chaing (superior cervical ganglion)

107
Q

Trochlear Nerve

A

CN IV
lies in the caudal midbrain at the level of inferior colliculus (IC)
cell bodies that give rise to the trochlear nerve are located in the contralateral trochlear nucleus, fibers decussate and exit the midbrain dorsally
-traverses the superior orbital fissure

108
Q

axons from the left trochlear nucleus cross in…

A

the midbrain and form the right trochlear nerve, innervating the right superior oblique muscle

109
Q

Cranial nerve VI

A

abducens nerve
innervates only one muscle, the lateral rectus

GSE

abducens nucleus is located in the caudal pons

transverses the superior orbital fissure

110
Q

Motor nuclei of CN III, IV, VI

A

do not receive direct input from the motor cortices

111
Q

Rapid eye movements

A

aka saccades
-mediated via projections from cortical eye fields (frontal, supplementary and parietal eye fields) to the reticular formation (midbrain and pons)

-reticular formation projects to the motor nuclei of III, IV, and VI which innervate the extraocular eye muscles

112
Q

What tracks visual stimuli that are moving?

A

smooth pursuit

113
Q

smooth pursuit movements/tracking

A

requires continuous feedback from the visual cortex, cortical eye fields, vestibular system and cerebellum to the motor nuclei of CN-III,IV and VI

these CNS regions are critical for maintaining the moving visual stimulus on the fovea

114
Q

Abducens nerve lesion

A

Ipsilateral eye exhibits medial strabismus (medial deviation/adduction of the eyeball)
medial strabismus occurs in the eye ipsilateral to the lesion because lack of innervation to the lateral rectus
-Medial rectus is unopposed

115
Q

medial strabismus

A

abnormal alignment of the eyes

116
Q

Oculomotor nerve lesion

A

ipsilateral eye is deviated laterally and slightly downward

  • lateral deviation - bc unopposed action of the lateral rectus
  • downward position- bc of unopposed action of the superior oblique
  • impaired vertical movements - bc loss of innervation to superior rectus, inferior rectus and inferior oblique
117
Q

diplopia

A

double vision - due to inability to direct both eyes toward the same object

118
Q

ptosis

A

drooping of eyelid because of deficient innervation to the levator palpebrae superiors muscle

119
Q

dilated/non reactive pupil

A

because of lack of parasympathetic innervation to pupillary constrictor muscle

Anatomy Test 3 (9 decks)

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