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Name characteristics of cranial nerves
- all are PNS, except the optic is a mixture of PNS & CNS
- associated with the brainstem and forebrain
- innervates structures of the head/neck region
- motor/sensory/mixed
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What are the different types of motor contributions?
- GSE/SVE: somatic, motor to skeletal, alpha fibers
- GVE: autonomic, motor to smooth, B fibers
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What are the different types of sensory contributions?
- GSA: general afferent, sensory from body
- GVA: sensory from viscera
- SSA/SVA: special, hearing/balance/vision (SSA), taste/smell (SVA)
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Which way do motor neurons travel?
- efferent- travel away
- higher centers --> brainstem nucleus --> brainstem
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Which way to sensory neurons travel?
- afferent- toward
- cranial nerve ganglion --> brainstem nuclei --> thalamus
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What splits the alar and basal plate?
sulcus limitans
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What is the difference between the alar and basal plates?
- alar: sensory, lies medial
- basal: motor, lies lateral
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From medial to sulcus limitans list the components of the basal plate:
GSE --> SVE --> GVE
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From lateral to sulcus limitans list the components of the alar plate:
GVA --> SVA --> GSA --> SSA
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List the function, nuclues, peripheral ganglia and target of the olfactory nerve:
- Function: SVA- smell
- nucleus: anterior olfactory nucleus
- peripheral ganglia: olfactory bulb
- peripheral target: nasal cavity
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List the function, nuclues, peripheral ganglia and target of the optic nerve:
- function: SSA- vision
- nucleus: lateral geniculate body
- peripheral ganglia: retina
- peripheral target: retina
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What is the different between the optic tract and optic nerve?
- optic tract: proximal from optic chiasm to LGB, mixed sensory signals from BOTH eyes
- optic nerve: distral from optic chiasm to LGB, info from ONE eye
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Where does the optic nerve relay information from?
from retina to optic chiasm
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Describe how the eye reacts to light:
- the rods and cones hyperpolarize when light hits them and shut off
- shutting off releases inhibitory cells that allow ganglion cells to fire that then depolarizes nerves traveling back to diencephalon
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What are the two different responses in the pupillary light reflex?
- direct response: eye you shine light in constricts
- consensual response: opposite eye you shine light in constricts
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Where do interneurons of the optic nerve cross over?
posterior white commissure
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If you shine a light in the RIGHT eye and there is no consensual or direct response, where is most likely the deficit?
RIGHT optic nerve- in afferent limb back to the tectum
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If you shine a light in the RIGHT eye and there is no consensual or but a direct response, where is most likely the deficit?
LEFT oculomotor nerve
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If you shine a light in the RIGHT eye and there is a consensual or but no direct response, where is most likely the deficit?
RIGHT oculomotor nerve
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What does it mean if you are checking for the pupillary reflix and the pupils are fixed?
damage to the midbrain region
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What two nerves need to be functioning for the pupillary reflex?
oculomotor for PSNS and optic nerve
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How does coordinated ocular movement occur?
bilateral connections among vestibular, oculomotor, and spinal accessory nerve nuclei in the brainstem send signals to the MLF
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What does coordinated ocular movements involve?
MLF and frontal eye fields
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What is the difference between convergence and divergence?
- convergence: ability of eye to adjust looking at something from a distance to far away
- divergence: movements that are going away
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What happens when your eyes converge?
- lens thicken and pupils constrict from PSNS of oculomotor nerve
- eyes converge from GVE of oculomotor nerve
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What's the difference between the pupillary light reflex and the accomodation-convergence reflex?
the accomodation convergence reflex requires cortical input unlike the pupillary reflex
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What are the five functions of the oculomotor nerve in eye movement?
- levator palpebrae superioris: lifts eyelid
- superior rectus: pupil up
- medial rectus: pupil medial
- inferior rectus: pupil down
- inferior oblique: eye adducted- pupil up, eye abducted- pupil rotates
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What is the main function of the trochlear nerve in eye movement?
superior oblique: eye adducted- pupil down, eye abducted- pupil rotates
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What is the main function of the abducens nerve in eye movement?
lateral rectus: pupil lateral
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What are the two functional components of the oculomotor nerve?
- GSE: extraocular eye muscle
- GVE: PSNS to eye
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List the function, nuclues, peripheral ganglia and target of the extraocular eye muscles of the oculomotor nerve:
- function: GSE- motor
- nucleus: oculomotor
- peripheral ganglia: none
- peripheral target: extraocular mm
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List the function, nuclues, peripheral ganglia and target of the PSNS to the eye:
- function: GVE- PSNS
- nucleus: Edinger-Westphal
- peripheral ganglia: ciliary
- peripheral target: contrict pupil and ciliary
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List the function, nuclues, peripheral ganglia and target of the trochlear nerve:
- function: GSE- superior oblique muscles bring eye in and down
- nucleus: trochlear
- peripheral ganglia: none
- peripheral target: superior oblique
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Which nerve is the only peripheral nerve to cross the midline?
trochlear- so if damage to the L trochlear nerve, will have deficits to the R superior oblique
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What are the two functional components of the trigeminal nerve?
- GSE: masticatory muscles
- GSA: general sensation to head and face
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List the function, nuclues, peripheral ganglia and target of the motor component of the Trigeminal nerve:
- function: GSE- masticatory muscles
- nucleus: motor nucleus of V
- peripheral ganglia: none
- peripheral target: muscles of mastication
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List the function, nuclues, peripheral ganglia and target of the sensory component of the trigeminal nerve:
- function: GSA- general sensation to head and face
- nucleus: SpV, PrV, mesV
- peripheral ganglia: trigeminal
- peripheral target: sensory of face
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What is the trigeminal complex?
continous column of cells from the dorsal horn of th ebrainstem thru the spinal trigeminal nucleus of the pons to the mesencephalic nucleus of the midbrain
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What nerve is the jaw-jerk monosynaptic reflex associated with?
trigeminal nerve
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List the function, nuclues, peripheral ganglia and target of the abducens nerve:
- function: GSE- lateral rectus (moves eye laterally or abducts pupil)
- nucleus: abducens
- peripheral ganglia: none
- peripheral target: lateral rectus mm
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What are the four functional components of the facial nerve?
- GSE: facial expression mm
- GVA: submandibular/sublingual gland
- SVA: taste
- GSA: general sensation of ear
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List the function, nuclues, peripheral ganglia and target of the motor component of the facial nerve:
- function: GSE- facial expression
- nucleus: facial
- peripheral ganglia: none
- peripheral target: mm of facial expression
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List the function, nuclues, peripheral ganglia and target of the GVA component of the facial nerve:
- function: GVA- submandibular/sublingual gland
- nucleus: superior salivatory
- peripheral ganglia: submandibular and sphenopalatine
- peripheral target: lacrimal gland and submandibular/lingual gland
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List the function, nuclues, peripheral ganglia and target of the taste component of the facial nerve:
- function: SVA- taste
- nucleus: rostral solitary
- peripheral ganglia: geniculate
- peripheral target: tongue
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List the function, nuclues, peripheral ganglia and target of the general sensory component of the facial nerve:
- function: GSA- sensation of ear
- nucleus: trigeminal
- peripheral ganglia: geniculate
- peripheral target: external ear
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What are the two functional components of the vestibulocochlear nerve?
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List the function, nuclues, peripheral ganglia and target of the hearing component of the vestibulocochlear nerve:
- function: SSA- hearing
- nucleus: cochlear (dorsal and ventral)
- peripheral ganglia: spiral
- peripheral target: cochlea
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List the function, nuclues, peripheral ganglia and target of the balance component of the vestibulocochlear nerve:
- function: SSA- balance
- nucleus: vestibular
- peripheral ganglia: vestibular
- peripheral target: vestibular app
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What are the functional components of the glossopharyngeal nerve?
- GSE: stylopharyngeus muscle
- GVE: PSNS to parotid gland
- SVA: taste (posterior 1/3 of tongue)
- GVA: carotid body sensation
- GSA: sensation from ear and tongue
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List the function, nuclues, peripheral ganglia and target of the motor component of the glossopharyngeal nerve:
- function: GSE- stylopharyngeus muscle
- nucleus: nucleus ambiguus
- peripheral ganglia: none
- peripheral target: mm of larynx
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List the function, nuclues, peripheral ganglia and target of the PSNS component of the glossopharyngeal nerve:
- function: GVE- PSNS to parotid gland
- nucleus: inferior salivatory
- peripheral ganglia: otic
- peripheral target: parotid gland
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List the function, nuclues, peripheral ganglia and target of the taste component of the glossopharyngeal nerve:
- function: SVA- taste
- nucleus: rostral solitary
- peripheral ganglia: inferior of IX
- peripheral target: tongue
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List the function, nuclues, peripheral ganglia and target of the carotid body sensation of the glossopharyngeal nerve:
- function: GVA- carotid body sensation
- nucleus: caudal solitary
- peripheral ganglia: inferior of IX
- peripheral target: soft palate & pharynx
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List the function, nuclues, peripheral ganglia and target of the general sensory portion o fthe glossopharyngeal nerve:
- function: GSA- general sensation from ear and tongue
- nucleus: trigeminal
- peripheral ganglia: superior or inferior of IX
- peripheral target: external ear
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What are the functional components of the vagus nerve?
- GSE: mm of larynx and pharynx
- GVE: PSNS to thorax and upper abdomen
- GVA: sensory from viscera (gut, lungs, heart)
- GSA: general sensation from inner ear
- SVA: taste
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List the function, nucleus, peripheral ganglia and target of the motor portion of the vagus nerve:
- function: GSE- mm of larynx and pharynx (help with swallowing, phonation and speaking)
- nucleus: nucleus ambiguus
- peripheral ganglia: none
- peripheral target: mm of larynx/pharynx
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List the function, nucleus, peripheral ganglia and target of the PSNS portion of the vagus nerve:
- function: GVE- PSNS to thorax and upper abdomen
- nucleus: dorsal motor
- peripheral ganglia: multiple
- peripheral target: viscera
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List the function, nucleus, peripheral ganglia and target of the taste portion of the vagus nerve:
- function: SVA- taste
- nucleus: rostral solitary
- peripheral ganglia: inferior of X
- peripheral target: epiglottis
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List the function, nucleus, peripheral ganglia and target of the sensory from viscera of the vagus nerve:
- function: GVA- sensory from viscera (gut, lungs, heart)
- nucleus: caudal solitary
- peripheral ganglia: inferior of X
- peripheral target: viscera sensory
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List the function, nucleus, peripheral ganglia and target of the general sensation of the vagus nerve:
- function: GSA- gereral sensation to the ear
- nucleus: trigeminal
- peripheral ganglia: superior of X
- peripheral target: external ear
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List the function, nucleus, peripheral ganglia and target of the accessory nerve:
- function: GSE- innervates trapezius and SCM
- nucleus: accessory muscle
- peripheral ganglia: none
- peripheral target: trapezius and SCM
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List the function, nucleus, peripheral ganglia and target of the hypoglossal nerve:
- function: GSE- tongue muscle
- nucleus: hypoglossal nucleus
- peripheral ganglia: none
- peripheral target: tongue mm
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What are the motor (GSE) nucleus of the cranial nerves?
- III (oculomotor)
- IV (trochlear)
- V (trigeminal)
- VI (abducens)
- VII (facial)
- XI (accessory)
- XII (hypoglossal)
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What are the parasympathetic (GVE) nuclei of the cranial nerves?
- Edinger Westphal nuclei (III-oculomotor)
- salivatory nuclei (VII-facial, IX- glossopharyngeal)
- dorsal motor nuclei of X (vagus)
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What are the taste (SVA) nuclei of the cranial nerves?
rostral solitary (VII-facial, IX-glossopharyngeal, X-vagus)
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What are the sensory from viscera (GVA) nuclei of the cranial nerves?
caudal solitary nuclei (IX-glossopharyngeal, X-vagus)
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What are the general sensory from the body (GSA) nuclei of the cranial nerves?
trigeminal (V- trigeminal)
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What are the hearing, balance, and vision (SSA) nuclei of the cranial nerves?
cochlear and vestibular (VIII- vestibulocochlear)
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What does a complete lesion to the olfactory nerve cause?
inability to smell
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What does a complete lesion to the optic nerve cause?
- ipsilateral blindness
- loss of pupillary light reflex
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What does a complete lesion to the oculomotor nerve cause?
- ptosis (eyelid drooping)
- ipsilateral eye looks outward and down
- diplopia (double vision)
- deficits in moving ipsilateral eye medially, downward and upward
- loss of pupillary light reflex and consensusual response
- loss of constriction of pupil
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Whats the difference between oculomotor nerve damage, UMN lesions or MLF lesions?
- reflexes producing pupillary constriction will be spared in UMN or MLF lesions
- both UMN and MLF lesions will have more extensive brainstem or cerebral signs and symptoms
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What does a complete lesion to the trochlear nerve cause?
- prevents activation of superior oblique muscle- ipsilateral eye can't look downward and inward
- double vision, difficulty reading, and visual problems going down stairs
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What does a complete lesion to the trigeminal nerve cause?
- anesthesia of area supplied by opthalamic, maxillary, or mandibular branch
- opthalamic- afferent limb of blink reflex affected so can't blink when cornea is touched
- mandibular- jaw deviates toward involved side when mouth is open and masseter reflex lost
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What does a complete lesion to the abducens nerve cause?
- eye will look inward because of paralysis of lateral rectus muscles
- can't volunatry abduct eye and will have double vision
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What does a complete lesion to the facial nerve cause?
- paralysis or paresis of ipsilateral muscles of facial expression
- one side of face droops and prevents person from being able to completely close ipsilateral eye
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What does a complete lesion to the vestibulocochlear nerve cause?
deafness/balance probelms
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What does a complete lesion to the glossopharyngeal nerve cause?
interrupts afferent limb of both the gag and swallowing reflex (vagus produces efferent limb to both)
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What does a complete lesion to the vagus nerve cause?
- difficulty speaking and swallowing
- poor digestion
- asymmetric elevation of palate
- hoarseness
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What does a complete lesion to the accessory nerve cause?
paralyzes ipsilateral SCM and trap
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What does a complete lesion to the hypoglossal nerve cause?
atrophy of ipsilateral tongue, causing difficulty speaking and swallowing
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