Unit 4: Cranial Nerves pg 121 - 137 Flashcards
(99 cards)
1
Q
Neuron cell bodies located in the trochlear nucleus are at the level of the
A
Inferior colliculus in midbrain
2
Q
Lesions of the trochlear nerve (CN IV) are
A
Unusual and difficult to detect
3
Q
Action of the superior oblique muscle:
A
- Depress
- Abduct
- some Intorsion (medial rotation)
…Of the eye.
4
Q
The superior oblique muscle is innervated by
A
Trochlear nerve (CN IV)
5
Q
Abducens nerve (CN VI) originates from abducens nucleus in the ______ within the _______
A
- Lower pons
- facial colliculus in the floor of the IV ventricle
6
Q
What innervates the lateral rectus muscle?
A
Abducens nerve (CN VI)
7
Q
Unilateral lesion of VI nerve or nucleus results in
A
- flaccid paralysis of ipsilateral lateral rectus muscle
- inability to abduct the ipsilateral eye
8
Q
Medial strabismus = esotropia
A
Eye is strongly adducted
9
Q
Diplopia
A
Double-vision
Occurs in medial strabismus (esotropia) because both eyes cannot look at the same target
10
Q
Oculomotor nerve (CN III) originates from
A
Oculomotor nuclear complex in the midbrain at the level of superior colliculus
11
Q
Oculomotor nuclear complex contains what nucleus?
A
Edinger-Westphal (E-W) nucleus
12
Q
Edinger-Westphal (E-W) nucleus is what kind of neurons
A
Preganglionic parasympathetic neurons (autonomic nucleus)
13
Q
Superior rectus and inferior rectus, medial rectus, inferior oblique and elevator palpebrae superioris are innervated by
A
CN III
14
Q
Action of superior rectus and inferior rectus, medial rectus, inferior oblique and elevator palpebrae superioris
A
- Adduction
- Vertical movement
15
Q
Preganglionic parasympathetic neurons (E-W neurons) innervate
A
Postganglionic parasympathetic neurons of the ciliary ganglion
16
Q
Postganglionic parasympathetic neurons of the ciliary ganglion innervate
A
- Constrictor pupillae
- Ciliary muscles
17
Q
Pupillary light reflex
A
Reflexive constriction of both pupils in response to increase in light intensity on the retina
18
Q
What do you expect to see in pupillary light reflex?
A
Contraction of the pupil of the stimulated eye AND contraction of the non-stimulated eye
19
Q
Afferent limb of pupillary light reflex is (and trace the pathway)
A
CN II
Requires visual p/way: optic nerve —> optic tract —> superior brachium —> synapse on pretectal nucleus —> send axons to both left and right E-W nuclei via posterior commisure
20
Q
Efferent limb of the pupillary light reflex is (and trace the pathway)
A
CN III formed by the right and left Edinger-Westphal nuclei
Send axons to ciliary ganglia —> innervate sphincter pupillae muscles of both eyes
21
Q
When you shine light in right eye and you expect to see a response in the right eye, its called what kind of response?
A
Direct pupillary light response (pupillary constriction of the eye)
22
Q
When you shine light in right eye and expect to see a response in the left eye, it’s called what?
A
Consensual (indirect) pupillary light response: pupillary constriction of non-stimulated eye
23
Q
Oculomotor nerve is at the level of the
A
Superior colliculi (upper midbrain)
24
Q
Reflexive actions that occur when one’s gaze is shifted from distance target to a nearer target
A
Accommodation or accommodation-convergence reflex
25
Convergence eyes is by the contraction of
Both medial recti muscles
26
Pupillary constriction of both eyes makes contraction of
Both sphincter pupillae muscles
27
Accommodation of both lenses uses the contraction of
Both ciliary muscles
This will increase convexity of the lenses and allow for focus on a near target
28
The neural pathway for the accommodation or accommodation-convergence reflex involves
CN II —> Optic tract —> LGB
29
Afferent limb of the accommodation or accommodation-convergence reflex
CN II
30
Efferent limb of accommodation or accommodation-convergence reflex
CN III
31
Unilateral lesion of CN III results in
1. Flaccid Paralysis (because damage to LMN fibers) of all ipsilateral mm innervated by CN III
- Superior and inferior rectus
- Medial rectus
- Inferior oblique
- Levator palpebrae superioris
—> Inability to adduct the eye and move eye vertically
—> lateral (external)strabismus would occur = eye strongly abducted
2. Ptosis = drooping of superior palpebrum (upper eyelid)
3. Loss of innervation to ciliary ganglion
—> no pupillary light reflex (direct nor consensual) response in ipsilateral eye (because motor efferent limb is interrupted)
—> dilation of pupil in ipsilateral eye
—> loss of accommodation of lens of ipsilateral eye
32
Weber’s Syndrome can be cause from
Vascular lesion of the anterior midbrain (basal part of cerebral peduncle)
Note: interrupting fibers of pyramidal system probably as well because cerebral crus is located here as well. The descending pyramidal fibers will be affected
33
Weber’s syndrome interrupts
Ipsilateral CN III and descending motor control fibers of cerebral crus (pyramidal system)
34
Weber’s syndrome results in
Ss/SXs of a CN III lesion of ipsilateral eye
UMN lesion:
- contralateral spastic hemiplegia
- contralateral spastic paralysis of muscles of facial expression of the contralateral lower 1/2 of the face and muscles of the contralateral tongue 👅
35
Trigeminal motor nucleus is located in
Upper pons
36
LMNs of V nerve receive what kind of innervation
Bilateral CB/CN innervation (review from exam 4)
37
CN V fibers exit the pons to innervate
- Muscles of mastication
- Tensor tympani m
- Tensor veil palatini m
- Mylohyoid m
- Anterior belly digastric m
38
Interruption of the motor fibers of the V nerve results in
Flaccid paralysis and eventual atrophy = deviation of the mandible
Note: Peripheral nerve lesion or CN nerve lesion are LMN lesions which result in flaccid paralysis. (UMN lesion result in spastic paralysis)
39
Lesion of the LEFT V nerve, the mandible will deviate towards what side?
LEFT side, the lesioned (paralyzed) side
40
CN VII (Facial) sensory fibers exit brainstem with CN VII preganglionic parasympathetic neurons as the
Nervus intermedius
41
Peripheral processes of the geniculate ganglion (primary neuron cell bodies of CN VII) for general S-S neurons innervate:
- Skin of external ear
- Wall of external auditory canal
- External surface of tympanic membrane
42
Trochlear and Abducens nerve fibers are entirely composed of ________.
LMNs
43
Axons of abducens nerve exit ______ surface of the brainstem at the ________.
- ventral surface
| - pontomedullary junction
44
Where in the pontomedullary junction is abducens nerve located?
Most medially
From medial to lateral, the cranial nerves in the pontomedullary junction are 6,7,8
45
Cranial nerve III/ oculomotor nerve contains what kind of fibers?
contains LMNs & autonomic preganglionic parasympathetic neurons
46
Axons of oculomotor nerve exit the brain stem at ________.
Interpeduncular fossa
47
Peripheral processes of the geniculate ganglion (primary neuron cell bodies of CN VII) for gustatory neurons innervate
- chorda tympani
| - greater petrosal nerve to the palate — taste receptors
48
Central processes of General SS Neurons of CN VII enter brainstem, join spinal trigeminal tract and synapse in the
2˚ Spinal trigeminal nucleus
49
General SS Neurons of CN VII terminate in where in the cortex
1˚ somatosensory cortex
50
Central processes of gustatory neurons of CN VII enter brainstem and terminate in the
Rostral part of the solitary nucleus
51
Two types of motor neurons/fibers of the facial nerve:
- Somatomotor neurons (LMNs)
| - preganglionic parasympathetic neurons
52
Afferents to the CN VII motor nucleus include
- Corticobulbar/C-N fibers (UMN)
- superior olivary nucleus for reflexive contraction of stapedius in response to loud noise
- SS input from sensory nuclei of trigeminal nerve CN V for stimulation of corneal reflex (“blink” reflex)
53
Preganglionic parasympathetic neurons of CN VII comprise 2 nuclear groups in the lower pons
1. Superior salivatory nucleus
| 2. Lacrimal nucleus
54
Fibers of the Superior salivatory nucleus are distributed in
Chorda tympani
55
Fibers of Superior salivatory nucleus (preganglionic parasympathetic neurons) terminate in ______ ganglion on what kind of neurons
Submandibular ganglion; postganglionic parasympathetic neurons
56
What do you expect in a full compression of all unilateral (CN VII) fibers
- paralysis of all upper and lower ipsilateral facial muscles
- paralysis of ipsilateral stapedius m —> hyperacusis
- diminished taste sensation of anterior 2/3 tongue
- decreased salivation —> dry mouth
- loss of direct & consensual corneal reflex of ipsilateral eye
- decreased /loss of lacrimation: no lacrimation, loss or decreased ability to blink ipsilaterally = increased contralateral blinking
57
IX nerve sensory components (3)
1. S-S neurons
2. Gustatory neurons
3. General visceral afferent neurons (GVAs)
58
Postganglionic parasympathetic neurons that terminated in submandibular ganglion provide secretomotor innervation to:
- submandibular gland
- sublingual gland
- lingual gland
- labial gland
59
The fibers of the lacrimal nucleus are distributed in
Greater petrosal nerve
60
Fibers of lacrimal nucleus terminate in _____ ganglion on what kind of neurons
Pterygopalatine ganglion (sphenopalatine ganglion) on postganglionic parasympathetic neurons
61
Postganglionic fibers that terminated on pterygopalatine ganglion provide secretomotor innervation to
- nasal glands
- palatine glands
- lacrimal glands
62
Common disturbance of CN VII is a condition called
Bell palsy
63
Bell Palsy could be caused by
increased pressure on VII nerve
- as it traverses facial canal in petrous temporal bone or
- as the motor root travels through the parotid gland
64
Glossopharyngeal nerve (CN IX) 3 sensory neurons
1. S-S neurons
2. Gustatory neurons
3. General visceral afferent neurons (GVAs)
65
S-S afferents of the IX nerve serve as the afferent limb of the
Gag reflex
66
Efferent limb of the gag reflex include which nerves
```
CN X (palate and pharynx mm)
CN XII (tongue mm)
CN V (mastication mm)
CN VII (facial expression mm)
```
67
Peripheral processes of CN IX distribute to the following areas
- posterior 1/3 tongue 👅
- upper pharynx
- tympanic cavity
- Eustachian tube
67
Peripheral process of CN IX gustatory neurons distribute through
Lingual branches of IX nerve to taste receptors on posterior 1/3 tongue 👅
69
Peripheral processes of GVAs (general visceral afferent neurons) of IX nerve distribute to specialized receptors in the:
```
Carotid sinus (baro)
Carotid body (chemo)
```
70
What do GVAs (general visceral afferent) do?
Reflex regulation of cardiovascular, respiratory, alimentary function
70
Carotid sinus is what kind of receptor
Baroreceptor
71
Carotid body is what kind of receptor
Chemoreceptor
72
CN IX 2 types of motor components:
LMNs and Autonomic neurons
73
Somatomotor neuron fibers distributed through pharyngeal branches of CN IX to supply:
Ipsilateral stylopharyngeus m
74
Somatomotor neurons of CN IX receive bilateral
CB/CN innervation
75
Preganglionic parasympathetic neurons of CN IX have cell bodies that comprise what nucleus?
Inferior salivatory nucleus (medulla)
76
Unilateral lesion of CN IX would lead to:
* loss of gag reflex (when ipsilateral posterior 1/3 tongue/upper pharynx stimulated)
* Decreased taste sensation
* Decreased salivation
* Paralysis of ipsilateral stylopharyngeus muscle
77
Vagus nerve (CN X) has 3 types of sensory fibers:
1. S-s neurons
2. Gustatory neurons
3. General visceral afferent neurons
78
Motor component for CN X includes 2 types:
LMNs and preganglionic parasympathetic neurons
79
Peripheral processes of the S-S neurons of Vagus Nerve innervate:
- Some external ear
- Portion of external auditory canal (these 2 bullet points along with C2, CN VII, V3 of CN V)
- Lower pharynx
- Larynx
- Upper esophagus
80
Peripheral processes of gustatory neurons of CN X (Vagus) innervate
Epiglottis
81
General visceral afferent neurons (GVAs) of CN X innervate:
- Baroreceptors in the aortic arch
- Chemoreceptors in the aortic arch
- Receptors in hollow organs through thoracic and abdominal cavities: GI tract through transverse colon
82
Somatomotor neuron cell bodies of CN X are located in nucleus ambiguus and emerge from brainstem as either/or:
- Part of vagus nerve or
| - as cranial root of spinal accessory nerve
83
Somatomotor neuron fibers of the X nerve supply:
- all muscles of palate (EXCEPT tensor veil palatini)
- m of pharynx (EXCEPT stylopharyngeus)
- m of larynx
- upper esophagus
84
Postganglionic fibers of CN X are distributed to visceral effector cells:
- cardiac m
- smooth m
- gland cells
85
Unilateral lesion of vagus nerve would result in:
- ipsilateral paralysis of all muscles of palate (except
tensor veli palatine), all muscles of pharynx (except stylopharyngeus), muscles of the larynx, & upper esophagus
- during phonation, uvula will deviate AWAY from lesioned side
Vocal fold dysfunction:
- some difficulty swallowing (dysphagia)
- some difficulty breathing (dyspnea)
- hoarseness of voice
86
bilateral lesion of vagus nerve:
Rare
- paralysis of laryngeal and pharyngeal muscles
Could be fatal
87
Spinal accessory nerve CN XI supplies what?
- sternocleidomastoid m
| - trapezius m
88
Accessory nerve (CN XI) has two roots
Spinal root
| Cranial root
89
Cell bodies of CN XI spinal root are located in ____ nucleus in the:
Spinal accessory nucleus; ventral horn spinal cord segments C1-C5
90
Cell bodies of CN XI cranial root located in
Nucleus ambiguus
91
At what foramen does the cranial roof CN XI join the vagus nerve and explain what it does
Enters Jugular foramen and provides X nerve innervation to muscles of palate and larynx
92
Inferior to jugular foramen, Spinal root of XI provides motor innervation to
- SCM
| - Trapezius
93
In regards to CN XI, unilateral Corticospinal/UMN lesions result in
Paralysis of contralateral trap and SCM muscles
| Because contralateral corticospinal innervation to LMNs of spinal root of CN XI
94
In regards to CN XI, unilateral peripheral XI nerve lesions result in
Ipsilateral trap and SCM paralysis
95
Hypoglossal nerve XII has LMNs fibers distributed to innervate:
All ipsilateral tongue muscles EXCEPT palatoglossus
96
Unilateral lesion of XII nerve results in
Paralysis of all ipsilateral tongue muscles
👅 will deviate towards the lesioned/paralyzed side
97
CN XI is associated with what foramen?
Jugular foramen
98
Unilateral Corticospinal/UMN lesions will result in what kind of deficit in regards to XII
Paralysis of contralateral tongue muscles (like CN XI)
Tongue will deviate toward the lesioned side (paralyzed side).
