Lecture 6

Question 1

study slide 4

Answer 1

ye

Question 2

study slide 6

Answer 2

ye

Question 3

what is CN I?

Answer 3

olfactory nerve

Question 4

what is CN II?

Answer 4

optic nerve

Question 5

what is CN III and its functions?

Answer 5

oculomotor nerve

• motor: levator palpebrae sup, all extraocular muscles (except SO and LR),
• parasymp. motor: pupi constriction and lens movement/ciliary muscles

Question 6

what is CN VI?

Answer 6

trochlear nerve; purpose is for SO

Question 7

what is CN V?

Answer 7

trigeminal nerve

• -sensation (touch, pain, temp, vibrations, proprioception) for the face (territories of V1, V2, and V3), mouth, ant 2/3s of the tongue, nasal sinuses, and meninges
• -pain is also supratenorial dura mater (above cerebellum)

-inns MOMs and tensor tympani muscle

Question 8

what is CN VI?

Answer 8

abducens nerve– inns LR

Question 9

what is CN VII?

Answer 9

facial nerve

• motor: muscles of facial expression, stapedius muscle, and part of digastric muscles
• parasymp: all glands but parotid
• special sensory: ant 2/3s of tongue taste
• sensation from small region near external auditory meatus

Question 10

what is CN VIII?

Answer 10

vestibulocochlear nerve

Question 11

what is CN IX?

Answer 11

glossopharyngeal nerve

–branchial motor: stylopharyngeus muscle

• parasymp: parotid gland
• general somatic sensory: -sensation from middle ear, region near EAM, pharynx, and post 1/3 of tongue

visceral sensory (special) = taste from post 1/3 of tongue

visceral sensory = chemo- and baroreceptors of carotid body

Question 12

what is CN X?

Answer 12

vagus nerve

– branchial motor: pharyngeal muscles (swallowing) and laryngeal = voice

–parasymp = heart, lungs, and G tract down to splenic flexure

–general somatic sensory: sensation from pharynx, meninges, and a small region near EAM

visceral sensory (special): taste from epiglottis and pharynx

–visceral sensory (general): chemo and baroreceptors of the aortic arch

Question 13

what is CN XI?

Answer 13

Accessory nerve

Question 14

what is CN XII?

Answer 14

hypoglossal nerve, for intrinsic muscles of the tongue

Question 15

describe the locations of the cranial nerves nuclei

Answer 15

CN I and II –> outside of the brainstain

CN III, IV,–> in the midbrain

CN V, VI, VII, VIII –> in the pons

CN IX, X, XI, XII –> in the midbrain

Question 16

describe conjugate eye movements on the cortical level

Answer 16

the visual cortex connects to the parieto-occipito-temporal area (ipsilateral pursuit and contralateral eye movements)

it also connects to the frontal eye fields–> contralateral saccades/scanning

the posterior eye field controls smooth pursuit

Question 17

why is conjugate eye movement important?

Answer 17

keeps vision in focus

Question 18

describe trigeminal neuralgia

Answer 18

• most often in the V2 or V3 region of face
• recurrent episodes of brief but severe pain
• easily triggered by light stimulus

Question 19

what are the CNs derived from ectoderm?

Answer 19

CN I, II, VIII

-purely sensory

Question 20

what are the CNs derived from neural crest?

Answer 20

V, VII, IX, X, XI

–from branchial arches, mixed (sensory and motor)

–special motor

Question 21

what are the CNs derived from mesoderm?

Answer 21

CN III, IV, VI, and XII

–somatic motor

Question 22

what do we mean by branchiomeric?

Answer 22

neural crest derived CNs (V, VII, IX, X, XI)

Question 23

describe the defecits seen in CN III lesions

Answer 23

-motor: ptosis (droopy eyelid); diplopia (double vision); impaired eye movements

• visceral motor deficits/parasym:
• -pupil dilation (mydriasis), (impaired pupillary light reflex). impaired accomodation

Question 24

describe the deficits seen in CN IV lesion

Answer 24

• diplopia

- impaired eye movements

Question 25

describe trigeminal nerve dysfunctin

Answer 25

-impaired chewing somatosensory deficits (head)

Question 26

describe facial nerve dysfunction

Answer 26

som. motor: -- impaired facial expression vis motor: - impaired salivation, earing somat. sensory deficits (ext ear) special sensory-->impaired aste

Question 27

CN VIII dysfunctions?

Answer 27

-nausea -dizziness -nystagmus impaired hearing

Question 28

what are vagus nerve dysfunctions?

Answer 28

somatic motor dysfunction - hoarseness - difficulty swallowing (may see pocketing) - impaired articulation - impaired gag reflex visceral motor dysfunction - impaired peristalsis - hypertension (impaired baroreflex) - resp defecits -somatosensory deficits (external ear) impaired taste

Question 29

what are glossopharyngeal nerve dysfunctions?

Answer 29

somatic sensory/motor: impaired gag reflex visceral motor dysf.: impaired salivation (xerostomia) and hypertension (impaired baroreflex) somatosensory dysf.: somatsens. deficits in external ear and impaired sensation in throat special sense dysf: impaired taste (post 1/3 of tongue)

Question 30

describe accessory nerve dysfunction

Answer 30

-drooping shoulder and impaired head turning

Question 31

describe hypoglossal nerve dysfunction

Answer 31

-impaired tongue movements - -if there is a UMN lesion, the tongue will deviate AWAY from the affected side (side of lesion)--contralateral - if it is an LMN lesion, the tongue will deviate ipsilateral (to the side of the lesion) -impaired articulation

Question 32

frontal eye fields control saccades-->high speed, voluntary movements; contralateral

Answer 32

ye

Question 33

posterior eye field (in parietal lobe) is for smooth pursuit; low speed smooth movement heavily influenced by visual input; IPSILATERAL

Answer 33

ye

Question 34

what is the MLF?

Answer 34

medial longitudinal fasciculus; is ensures that eye muscles work together to keep the visual image centred on the FOVEA --coordinates activity of CN III, IV, and VI --e.g. both eyes move to right, so the lateral rectus of the right eye is activated, but not the lat rec of left for CONJUGATE EYE MOVEMENT

Question 35

study slide 44

Answer 35

ye

Question 36

describe right oculomotor nerve palsy

Answer 36

-ptosis--droopy eyelid --unopposed SO and LR--> eye looking down and out

Question 37

describe right trochlear nerve palsy

Answer 37

right eye is looking up and out (lose intorsion and depression of eye) people will turn their head to focus on you

Question 38

describe CN VI nerve palsy (right)

Answer 38

right eye -->try to look right, but right LR cannot pull eye outwards (cannot abduct) --diplopia

Question 39

trigeminal nerve fibres enter the CNS at the level of the brainstem (midbrain, pons, medulla)

Answer 39

ye

Question 40

describe where all the sensory nuclei of CN V are found in the brainstem

Answer 40

--the MESENCEPHALIC (midbrain-located) nuclei--mostly convey proprioceptive info, and sensory cell-bodies located in the nucleus --in the pons, the main sensory nuclei (the primary neuron of the trigeminal nuclei) are the GSA fibres conveying discriminative touch into the nucleus --in the medulla, the DESCENDNG spinal nuclei are found--mayb convey temp and pain info to sensory bodies in the trigeminal nucleus; they also receive fibres from VII, IX, and X for visceral afferents of larynx and pharynx

Question 41

what is infratenorial pain conveyed by?

Answer 41

-CN X, XI, and first three cervical nerves

Question 42

what are corticobulbar pathways?

Answer 42

motor pathways of cranial nerves which parallel the corticospinal tract --most commonly they refer to motor pathways from CN V, VII, IX, some of X, and XII, and they derive from the cortex (UMNs) and synapse on LMNs

Question 43

study slide 58

Answer 43

ye

Question 44

UMN lesions cause weakness (paresis) on the CONTRALATERAL bottom 2/3s of the face as the LMNs only receive unilateral inn, while LMN lesions causes IPSILATERAL weakness on one side of the face (forehead not spared)- STUDY SLIDE 59

Answer 44

ye

Question 45

cranial nerve 12--inn the intrinsic muscles of the tongue, and if the right UMN is damaged, there is hemiparesis on the CONTRALATERAL (left) side, and if the LMN is damaged, it is ipsilateral

Answer 45

ye

Question 46

describe the pupillary light reflex

Answer 46

CN II receives light input unilaterally--synapse on the edinger-westphal nucleus (in the midbrain) which send BILATERAL autonomic output via CN III to BOTH eyes does not require cortical input or extraocular muscles

Question 47

describe the corneal reflex

Answer 47

irritation on one cornea-->unilateral input via CN V; synapse to CN VII which has BILATERAL output--> and causes both eyes to blink

Question 48

study slide 66

Answer 48

ye

Question 49

describe the gag reflex

Answer 49

sensory via glossopharyngeal if the soft palate or post pharynx is touched (back of tongue?) to the medulla --> to vagus--> vagus causes palate elevation and contraction of pharyngeal muscles

Question 50

what is the cerebellopontine angle?

Answer 50

the region where, if a lesion occurs there, the person will xperience dizziness and nausea (lateral, vestibulocochlear nerve located)