Cranial Nerves Flashcards
1
Q
what side of the brain are the cranial nerves
A
ventral side
2
Q
name of cranial nerve 1
A
CNI
olfactory nerve
2
Q
how many cranial nerves
A
12 pairs
3
Q
name of cranial nerve 2
A
CNII
optic nerve
4
Q
name of cranial nerve 3
A
CNIII
oculomotor
5
Q
name of cranial nerve 4
A
CNIV
trochlear nerve
6
Q
name of cranial nerve 5
A
CNV
trigeminal nerve
7
Q
name of cranial nerve 6
A
CNVI
abducens nerve
8
Q
name of cranial nerve 7
A
CNVII
facial nerve
9
Q
name of cranial nerve 8
A
CNVIII
vestibulocochlear nerve
10
Q
name of cranial nerve 9
A
CNIX
glossopharyngeal nerve
11
Q
name of cranial nerve 10
A
CNX
vagus nerve
12
Q
name of cranial nerve 11
A
CNXI
(spinal) accessory nerve
13
Q
name of cranial nerve 12
A
CNXII
hypoglossal nerve
14
Q
what nerves are eye related
A
2
3
4
6
15
Q
cranial nerves 2 3 4 and 6 are related to what?
A
eye
16
Q
number of olfactory nerve
A
1
17
Q
number of optic nerve
A
2
18
Q
number of oculomotor nerve
A
3
19
Q
number of trochelar nerve
A
4
20
Q
number of trigeminal nerve
A
5
21
Q
number of abducens nerve
A
6
22
Q
number of facial nerve
A
7
23
Q
number of vestibular cochlear nerve
A
8
24
number of glossopharyngeal nerve
9
25
number of vagus nerve
10
26
number of spinal accessory nerve
11
27
number of hypoglossal nerve
12
28
are the cranial nerves in the CNS or PNS?
PNS
29
role of cranial nerve 1- olfactory
special sense of smell
30
where is CNI?
olfactory nerve fibres project into the mucosa of the nasal cavity through the cribriform plate of the ethmoid bone
olfactory bulb is superior to the cribriform plate
olfactory tract connects bulb with forebrain e.g. amygdala (memory and associative learning)
31
which nerve is the only one directly connecting to the cerebrum?
CNI - olfactory
32
route of olfaction
When you take a big breath in through the nose, small particles and chemicals land on the moist nasal mucosa consisting of olfactory epithelium and contains chemoreceptors.
- Nasal lining is stimulated and therefore stimulate the olfactory sensory neurons which transmit signals to the brain via the olfactory nerve (cranial nerve 1) and the brain interprets the information (the smell)
33
what type of nerve is CNI?
sensory
34
damage to the olfactory nerve
hyposomnia
anosmia
cacosmia
35
hyposmia
reduced sense of smell
36
anosmia
complete loss of olfaction
37
cacosmia
persistent offensive smell with no obviously offensive external stimulus
38
role of CNII - optic nerve
vision
39
where is CNII?
single optic nerve leave posterior eye and joins with contralateral nerve from the other side
forms an x-shape called optic chiasm (located superior to the pituitary gland and sella turcica of the sphenoid bone).
40
lateral route of vision
single optic nerve leave posterior eye and joins with contralateral nerve from the other side to form the optic chiasm (located superior to the pituitary gland and sella turcica of the sphenoid bone).
at the chiasm, some visual info crosses over and some remains on the same side.
a left and right optic tract forms in which nerves project to the left and right lateral geniculate ganglion/nucleus (LGN) of the thalamus.
from the thalamus, optic radiations travel to occipital lobe (primary visual cortex)
41
what is the lateral route of vision involved in?
conscious vision or sight
42
medial route of vision
bypasses the LGN of the thalamus, instead projecting neurons to midbrain (pretectal nucleus and superior colliculus)
destination of 10% of neurons
43
what is the medial route of vision for?
non-conscious functions of the eye e.g. light reflex (afferents)
44
medial route of vision connects to which cranial nerves?
3 4 6 so plays a role with smooth pursuit and gaze
45
what type of nerve is CNII?
sensory
46
foramina for CNI
cribiform plate
47
foramina for CNII
optic canal
48
clinical relevance for CNI
anosmia
49
clinical relevance for CNII
bitemporal hemianopia
50
role of CNIII - oculomotor nerve
eye movements, pupillary constriction and accommodation (motor innervation of the superior, inferior, and medial recti muscles and inferior oblique muscle) (parasympathetic fires to ciliary muscles, constrictor pupillae)
innervates the muscle of the upper eyelid (parasympathetic fibres to elevator palpebrae superioris)
51
route of CNIII
leaves ventral side of the midbrain
passes through cavernous sinus via superior orbital fissure at the posterior orbit (formed by sphenoid bone of the skull)
52
3rd nerve palsy
pupil down and out at rest (depressed and abducted)
ptosis of eyelid and dilated pupil (parasympathetic switched off and therefore sympathetic causes dilation)
53
light relfex involves which cranial nerves
2 and 3
54
afferent part of light reflex
via optic nerve - info passes into midbrain via medial route of optic pathway
55
efferent part of light reflex
via oculomotor nerve and specifically the parasympathetic fibres passing along its route (provides motor supply to constrictor pupillae muscles of iris).
56
difference between limbs of the light reflex
the two nuclei that facilitate it are different
pretectal nucleus and Edinger-Westphal nucleus
57
what is the accommodation reflex?
provides dynamic changes to the lens of the eye allowing us to focus on near or far objects
constriction of iris and ciliary muscles
partly conscious - somatic nucleus from brainstem realys info to occipital lobe to cause convergence via extraocular muscles to converge the eyes
58
role of nerves in the accommodation reflex
optic and oculomotor nerves act as the afferent and efferent fibres for the reflexive function
Edinger-Westphal and pretectal nuclei vital for relaying and coordinating a bilateral and simultaneous response.
59
what type of nerve is CNIII
motor
60
foramina for CNIII
superior orbital fissure
61
clinical relevance of CNIII
ptosis of the eyelid
deviation of the pupil to down and out position
62
role of CNIV - trochlear nerve
innervates superior oblique extraocular muscle of eye to pull eye down and out (intorsion and downwards gaze)
63
route of CNIV
leaves the dorsal midbrain transverse the cavernous sinus and leaves the cranial cavity via the superior orbital fissure
63
4th nerve palsy
weakens the ability of eyes to look down and out, causing vertical diplopia
63
only cranial nerve to leave the dorsal midbrain
CNIV
64
clinical relevance of trochlear nerve
vertical diplopia
64
vertical diplopia
duplicated images on top of one another (eye drifts up at rest) - due to 4th nerve palsy
64
foramina of trochlear nerve
superior orbital fissure
64
what type of nerve is CNIV?
motor
65
role of CNV - trigeminal
carry somatic sensory afferent neurons that provide sensations to the face, teeth, mouth (anteriorly), cornea, nasal cavity and dura mater of cranial activity.
smaller motor component, innervating muscles of mastication and four other muscles of the head and neck
66
how many trigeminal branches are there?
3
66
3 trigeminal branches
ophthalmic (CNV1)
Maxillary (CNV2)
mandibular (CNV3)
67
trigeminal branch 1 name
ophthalmic
68
trigeminal branch 2 name
maxillary
69
trigeminal branch 3 name
mandibular
70
role of trigeminal branch 1
sensation to cornea, nose, forehead
71
role of trigeminal branch 2
sensation to lower nasal passages, cheeks, upper lip
72
role of trigeminal branch 3
sensation to chin, lower lip, anterior jaw, muscles of mastication and touch to anterior 2/3 of tongue
73
foramina of CNV1
superior orbital fissure
74
foramina of CNV2
foramen rotundum and then inferior orbital fissure
75
foramina of CNV3
foramen ovale
76
damage to trigeminal nerve
sensory loss - paraesthesia
(depending on which branch is irritated)
neuropathic pain in one or more branches - trigeminal neuralgia
77
what type of nerve is CNV?
mixed
78
clincial relevance of CNV
facial neuralgia
79
role of CNVI
motor innervation of the lateral rectus (extraocular muscle of the eye) (abducts the eye)
lateral gaze
80
what muscle abducts the eye?
lateral rectus
81
motor innervation of the lateral rectus
CNVI
82
Where does the abducens nerve emerge and travel?
emerges from the ventral pons and passes through the cavernous sinus, leaving the skull through the superior orbital fissure
83
palsy of CNVI
eye drifts medially at rest (towards nose)
experienced as horizontal diplopia (double vision)
84
horizontal diplopia
double vision with duplicated images side by side
85
what type of nerve is CNVI?
motor
86
foramina of CNVI
superior orbital fissue
87
clinical relevance of CNVI
unable to gaze laterally
horizontal diplopia
88
what are cranial nerve nuclei
collections of neuronal cell bodies of the corresponding nerves
89
where are the cranial nerve nuclei
brainstem
90
where are the nuclei for CNI?
above the midbrain - doesn't have a nucleus but has multiple nerves projecting to the olfactory bulb and synapse in forebrain
91
where are the nuclei for CNII?
above the midbrain - lateral geniculate nucleus (LGN) of the thalamus
92
where are the nuclei for CNIII?
midbrain
93
where are the nuclei for CNIV?
midbrain
94
where are the nuclei for CNV?
pons - 4 trigeminal nuclei (2 in pons which are the principle sensory and motor and then the mesencephalic sensory is in the midbrain and the spinal sensory is in the medulla).
95
where are the nuclei for CNVI?
pons
96
where are the nuclei for CNVII?
motor nucleus in the pontine segment - pons
97
where are the nuclei for CNVIII?
two parts - vestibular nucleus in pons and medulla and cochlear nucleus in pontine-medullary junction
98
where are the nuclei for CNIX?
solitary nucleus (inferior pons but mostly medulla) for special sense of taste
99
where are the nuclei for CNX?
four nuclei all in medulla including the vagus nucleus, nucleus ambiguous nd solitary nucleus
100
where are the nuclei for CNXI?
medulla - nucleus ambiguous for cranial component and nuclei in cervical spinal cord for spinal part.
101
where are the nuclei for CNXII
medulla
102
solitary nucleus role
sensory nucleus serving CNVII, CNIX, CNX
special sense of taste
chemoreceptors and mechanoreceptors from the carotid body, carotid sinus, aortic bodies, and SA node of the heart.
103
nucleus ambiguus role
motor nucleus serving CNIX and CNX
motor to ipsilateral muscles of the soft palate, pharynx and larynx involving in speech and swallowing
cranial part of the accessory nerve
104
blood supply to the pons
basilar artery runs over pons
pontine arteries run off of basilar artery and into pons
105
damage to pons consequences
impairment to eyes, movements, etc
106
locked in syndrome
blocking of basilar artery
cannot consciously or voluntary speak or make facial expression, make body movements below eyes, chew or swallow
can move eyes vertically but not laterally, blink, hear, think, and reason, have sleep and wake cycles, etc
107
role of the medullary olive
inferior olivary nucleus either side of pyramids
movement regulation, sound location, etc
spiral shape
108
test for CNI
sniffing sticks
109
test for CNII
Snellen chart, pen torch
○ Accommodation reflex (convergence, constriction, contraction)
110
test for CNIII
pen torch
111
test for CNV
brush face with cotton wool, clench teeth and check muscles of mastication, brush cotton wool on the cornea and check for blinking
112
corpora quadrigemina
- 2 superior colliculi: allow you to track something across your vision, reflexive action of looking at a flash etc. (abducens nerve), hand-eye coordination and saccades
- 2 inferior colliculi: sound localisation and integration
113
cranial palsy of abducens nerve
- Paralysed lateral rectus
- Other muscles unopposed
- Eye turned in when trying to look straight
- Horizontal double vision
114
cranial nerve palsy of trochlear nerve
- Vertical diplopia
- Pupil drifts upwards
115
cranial nerve palsy of oculomotor nerve
- Unopposed action of other muscles
- The eye looks down and out
- Dilated pupil unopposed sympathetic supply (consensual reflex in opposite eye is intact
- Unable to turn eye up, in or further out
- Ptosis of eyelid is most obvious sign
116
role of CNVII
innervating muscles of facial expression
parasympathetic supply to the glands of the face - lacrimal and salivary
taste from anterior 2/3 of tongue
117
where does CNVII leave the brainstem and where does it pass?
leaves the pons (pontomedullary junction) passing into temporal bone via the internal acoustic meatus.
meanders through inner and middle ear in facial canal giving off branches.
leaves temporal bone via the stylomastoid foramen running through the parotid to give of final motor branches to facial muscles
118
intratemporal branches of facial nerve
greater petrosal nerve
chorda tympani
nerve to stapedius
119
greater petrosal nerve
intratemporal branch of facial nerve
parasympathetic innervation of lacrimal glands and glands of nasal mucosa
120
chorda tympani
carries special sensory afferents of taste from anterior 2/3 of tongue
parasympathetic fibres to sublingual and submandibular salivary glands
121
nerve to stapedius
motor innervation to stapedius muscle which dampens vibrations transmitted through ossicles during a loud sound (protective to noise damage od the cochlea)
122
motor branches of the facial nerve
temporal
zygomatic
buccal
marginal mandibular
cervical
123
where do the 5 branches of the facial nerve split?
parotid plexus - as the facial nerve passes through the parotid gland
124
common facial nerve palsy
bells palsy
125
Bell's palsy
most common type of facial palsy caused by viral infection
LMN palsy resulting in loss of lacrimation, hyperacusis and facial weakness involving all motor branches
126
where are LMN found?
below the facial nerve nucleus (inside the cranial nerve)
below the pons
127
where are UMN found?
above the pons (facial nerve nucleus), projecting from the primary motor cortex (precentral gyrus) to the facial nerve nucleus.
128
where are UMN lesions found?
brain or brainstem above the facial nerve nucleus
129
example of UMN lesion condition
stroke
130
is stroke UMN or LMN lesion?
UMN
131
which motor branch of facial nerve is the focus for identifying an UMN or LMN injury and why?
temporal - only motor branch of the facial nerve to receive bicortical representation (both primary motor cortices provide neurones)
132
only partial facial weakness represents what?
lesion above the facial nerve nucleus - UMN injury
133
why is there only partial facial weakenss in one-sided UMN injury?
temporal branch of effected facial nerve will still receive motor innervation from unaffected cerebral hemisphere
134
where is damage in LMN palsy?
after the facial nerve nucleus
135
result of LMN palsy
whole face is weak as hemispheres have already crossed over
136
paralysis of facial muscles effect on eyes
dry eyes are damage to the supply of lachrymal glands, but watery eyes are more common as a patient are unable to close their eyes so the windscreen wiper motion of blinking doesn't happen
137
explain what happens if a patient has a stroke on the left side of the brain
If a patient has a stroke on the left side of the brain the right side of the face will be weak
- As left-sided strokes damage the UMN in the left side of the brain stopping signals reaching the LMN innervating the right side of the face
- Right sided UMN are still able to innervate the right side of the face so despite facial weakness on the right side, they can still raise their eyebrows on the weak side
- UMN facial palsy
138
what type of lesion if they can raise their eyebrows
UMN - e.g. stroke
139
what type of lesion if they can't raise their eyebrows
LMN palsy
140
explain the effect of right-sided UMN lesion
- Right side of the face is mostly innervated by the left side of the brain
- Going to effect the cortex, taking out the fibres as they cross over
- But the temporal branch of the facial nerve on the right side of the brain will still innervate the right side of the face and therefore not the whole side will be effected
○ The forehead/eyebrow (temporal) region will remain unaffected.
141
explain the effect of right-sided LMN lesion
- Whole face effected including the eyebrows and forehead
- Injury after the brainstem (in the LMN) so all innervations will be effected so the whole side of the face will be effected.
142
what type of nerve is CNVII
mixed
143
foramina for CNVII
internal acoustic meatus (IAM)
144
clinical relevance of CNVII
bell's palsy
145
role of CNVIII
special sensory info about balance, acceleration, gravity and hearing
146
hearing is which branch of CNVIII?
cochlear
147
balance is which branch of CNVIII?
vestibular
148
CNVIII nerves pass through and travel to where?
internal acoustic meatus along with facial nerve and travel to petrous part of temporal bone where inner and middle ear are
reappears inside the cranial cavity and travels to auditory centres within brain
149
damage to CNVIII can cause what?
vertigo
sensorineural hearing loss
150
vestibular nerve of CNVIII
sensory info about movement
Scarpa's (vestibular) ganglion in IAM
bipolar neurons here
151
cochlear nerve of CNVIII
bipolar neurons
spiral ganglion
central processes form the cochlear nerve
bigger than vestibular nerve
152
tests for CNVIII
tuning forks (Weber's and Rinne's tests)
balance tests
153
what type of nerve is CNVIII?
sensory
154
foramina of CNVIII
internal acoustic meatus (IAM)
155
clinical relevance of CNVIII
hearing loss
vertigo
156
role of CNIX
sensation and taste from posterior 1/3 of tongue and pharynx
innervates the parotid gland - parasympathetic
Sensory innervation: eustachian tube, middle ear, tonsils, soft palate, posterior tongue (last 3 are GAG reflex).
Carotid sinus/body: visceral sensory receptors monitor BP.
Motor to stylopharyngeus muscle as runs past styloid process
157
where does CNIX emerge and travel?
emerges from medulla and passes through jugular foramen
158
tests for CNIX
- Test back of tongue by getting patient to say ahhhh and looking at the soft palate
○ Soft palate should raise symmetrically
§ Failure for soft palate to rise suggests a pathology on that side
- Test cough and swallow
159
nuclei of CNIX
solitary nucleus
spinal trigeminal nucleus
nucleus amibuus
inferior salivary nucleus
160
neuralgia of CNIX
§ Pain will be localised in the posterior tongue and walls of the pharynx
§ Can be triggered by swallowing or speaking
§ Treat by severing the spinal trigeminal tract
161
what type of nerve is CNIX?
mixed
162
foramen of CNIX
jugular foramen
163
clinical relevance of CNIX
dysphagia - difficulty swallowing
164
longest cranial nerve and its route
CNX - vagus
runs from medulla to GI tract
165
role of CNX
general sensation - larynx, EAM, baroreceptors and chemoreceptors around aortic arch
motor - muscles of soft palate, larynx and pharynx for swallowing, phonation (speech)
parasympathetic - thoracic and abdominal viscera (heart, lungs, GI tract)
special sense of taste - epiglottis
166
where does CNX leave and travel?
leaves medulla and transverses the jugular foramen following the route of the internal jugular vein and internal carotid vessels inferiorly.
deep in the neck in a connective tissue tube of fascia called a carotid sheath
167
what type of nerve is CNX?
mixed
168
foramina of CNX
jugular foramen
169
clinical relevance of CNX
dysphonia - speech impaired
170
tests for CNX
test back of tongue by getting patient to say ahhhh and looking at the soft palate
○ Soft palate should raise symmetrically
§ Failure for soft palate to rise suggests a pathology on that side
- Test cough and swallow
Can also test the vagus nerve by:
- Testing speech:
171
role of CNXI
carries somatic motor innervation to the sternocleidomastoid and trapezius muscles
172
where does CNXI receive rootlets from and where do they go?
5 superior cervical segments of spinal cord
they ascend into the cranial cavity through foramen magnum and join neurons exiting the medulla which exits skull via jugular foramen
173
damage to CNXI
unilateral damage causes weakness of muscles (winged scapula)
unable to shrug shoulders
174
tests for CNXI
shrug shoulders
175
where on medulla is CNXI?
posterior to olive
176
what type of nerve is CNXI?
motor
177
foramen for CNXI
in through foramen magnum and out through jugular foramen
178
clinical relevance of CNXI
winged scapula
inability to shrug shoulders
179
role of CNXII
motor innervation to all intrinsic and extrinsic tongue muscles
180
where does CNXII leave and go?
leaves ventral medulla and passes through Hypoglossal canal of occipital bone
181
result of damage to CNXII
tongue muscle paralysis
182
evidence of LMN palsy in CNXII
fasciculations and muscle atrophy
Deviates towards the injury (LMN) (UMN injury indicated by the tongue doing the opposite)
183
tests for CNXII
- Test for nerve weakness by asking patient to protrude their tongue (stick tongue out)
184
why is spicy food spicy?
Hot and spicy foods taste hot because of capsaicin (active component of chilli peppers)
- Triggers temperature receptors in tongue (actually a general sensation of heat/temperature - temperature receptors are normally triggered at 42 degrees)
○ Carried by trigeminal nerve as general
185
what type of nerve is CNXII?
motor
186
foramina for CNXII
hypoglossal canal
187
clinical relevance of CNXII
hemiparalysis of the tongue
tongue deviates towards the damaged side
188
which cranial nerves are sensory
1
2
8
189
which cranial nerves are motor
3
4
6
11
12
190
which nerves are mixed
5
7
9
10
191
cribiform plate is foramina for which nerve
CNI
192
optic canal is foramina for which nerve
CNII
193
superior orbital fissure is foramina for which nerves
3
4
5
6
194
superior orbital fissue, foramen rotundum and foramen ovale are the foramina for which nerve
CNV
195
foramen rotundum is foramen for which nerve
CNV
196
foramen ovale is foramina for which nerve
CNV
197
IAM is foramina for which nerves
7
8
198
jugular foramen is foramina for which nerves
9
10
11
199
hypoglossal canal is foramen for which nerve
CNXII
200
foramen magnum is for which nerve
CNXI
