Cranial Nerves and Corticospinal Tract Flashcards by Alice Richards

afferent and efferent limbs of pupillary light reflex

afferent: CN II
efferent: CN III

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afferent and efferent limbs of eye accommodation

afferent: CN II
efferent: CN III

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eye accommodation:

afferent limb:

efferent limb:

afferent: CN II → optic
efferent: CN III → oculomotor

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what n controls movement of superior oblique m

CN IV

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what extrinsic eye muscles does CN III innervate (5)

superior rectus

medial rectus

inferior rectus

inferior oblique

levator palpebrae

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motor fxn of CN IV (trochlear)

intort, abduction → reading book and walking downstairs

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CN IV (trochlear) is vulnerable to __ injury

shear

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motor fxn of CN V

biting/chewing/mastication

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V1 is same-same

ophthalmic

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V2 is same-same

maxillary

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V3 is same-same

mandibular

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PSNS motor fxn of V2 (maxillary)

lacrimal gland/nose secretions

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sensory fxn of CN V

sensation to face, mouth, nose, eyes

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afferent and efferent limbs of the corneal (blink) reflex

afferent: Vi (ophthalmic)
efferent: CN VII → orbicularis oculi

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pathway of corneal (blink reflex)

V1 sense stimulus on cornea (afferent) → brainstem → CN VII (efferent) initiates motor response on both sides via orbicularis oculi

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motor fxn of V3

mastication

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afferent and efferent limbs of jaw jerk reflex

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PSNS fxn of V3

submandibular/sublingual gland secretions

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sensation (not taste) to anterior ⅔ of tongue

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motor fxn of CN VI

abduction of eye → outward gaze

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what m does CN VI innervate

lateral rectus

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special sensory fxn of CN VII

taste to anterior ⅔ of tongue

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motor fxn of CN VII

muscles of facial expression

dampening of sound in ear

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PSNS fxn of CN VII

lacrimal gland

submandibular gland

efferent blink reflex

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what m is associated w. taste to anterior ⅔ of tongue

chorda tympani

special sensory fxn of CN VIII (vestibulocochlear)

balance hearing

motor fxn of CN IX

gagging swallowing uvula salivation

special sensory fxn of CN IX

taste sensation to posterior ⅓ of tongue

taste to anterior ⅔ of tongue: taste to posterior ⅓ of tongue:

anterior ⅔: CN VII posterior ⅓: CN IX

special sensory fxn of CN X

taste to epiglottis

somatic motor fxn of CN X

efferent of soft palate swallowing gag reflex tongue retraction/elevation “Ahhh”

PSNS motor fxn of CN X

smooth m and glands in pharynx, larynx, thoracic, abd viscera

sensory fxn of CN X

sensation fo abd viscera

afferent and efferent limbs of cough reflex

CN X

motor fxn of CN XI (spinal accessory)

sternocleidomastoid trapezius

motor fxn of CN XII

intrinsic and extrinsic m of tongue

corneal blink reflex pathway

touch on the cornea → CN V1 (ophthalmic) → spinal nucleus of CN V → CN VII nucleus → CN VII → orbicularis oculi → blink

reflex arc for gag reflex (same-same pharyngeal reflex)

touch to posterior pharyngeal wall → sensed by CN IX (afferent) → brainstem → CN X → elevation of soft palate

loss of gag reflex could mean damage to either

CN IX CN X

how do you determine which n is damaged in the absence of gag reflex

have the pt say “Ahh”

if the pt says “Ahh” and there is no soft palate elevation, which n is damaged

CN X

sensory from carotid body chemoreceptors and baroreceptors

CN IX

sensory from aortic chemo and baroreceptors

CN X

baroreceptor reflex

hypotn → decreased bp → decreased stretch → sensed by CN IX and CN X → decreased afferent baroreceptor firing → increased SNS firing and decreased PSNS firing → vasoconstriction → increased HR and contractility → increased BP

carotid massage effect

carotid massage → increased pressure → increased stretch sensed by CN IX baroreceptors → increased afferent firing → increased AV node refractory period → decreased HR

which CN carry parasympathetic fibers

III VII IX X

constrictor of pupil and ciliary body

CN III

secretion of lacrimal, submandibular gland, and nasal glands

CN VII

secretions of parotid gland

CN IX

PSNS innervation to thoracic and abd viscera

CN X

PSNS innervation to thoracic and abd viscera

CN X

PSNS CN nerves __ (3) go to PSNS ganglia and then join branches of CN __ to their end organs

III, VII, IX V

corticospinal pathways go through the

internal capsule

what are the 3 sensory pathways of the spinal cord

dorsal column medial meniscus spinocerebellar tracts spinothalamic tracts *blue in the picture*

what are the 2 motor pathways of the spinal cord

pyramidal extrapyramidal *red in the picture*

the dorsal medial lemniscus tract controls (3)

tactile discrimination conscious proprioception kinesthetic sensation

tactile discrimination includes (4)

discriminative touch vibration fine pressure two point discrimination

kinesthetic sensation includes (2)

position movement

the spinocerebellar tract controls

unconscious proprioception

the spinothalamic tract controls

pain temp and itch → LSTT light touch → VSTT

the pyramidal tract controls

voluntary motor activity

the extrapyramidal tract controls

involuntary movement involuntary breathing/shivering maintains posture and balance

Parkinson's is a dz of the

extrapyramidal tracts

90% of the pyramidal tract decussates in the

medulla oblongota

10% of the pyramidal tract decussates in the

anterior corticospinal tract

the dorsal columns medial lemniscus decussates in the

medulla

the lateral spinothalamic tract decussates

at or near the level that the sensory nerve enters the spinal cord

the ventral spinothalamic tract decussates

at the level of the nerve entrance to the spinal cord OR up to 10 levels above

all nerves of the ventral (anterior) spinothalamic tract have crossed the midline by \_\_

the time they have reached the thalamus

summary of spinal cord decussations

In Brown Sequard Syndrome, \_\_, \_\_, and __ are lost on the same side below the lesion (ipsilateral)

proprioception vibration fine touch

in Brown Sequard Syndrome, \_\_ and __ are lost on the opposite side of the lesion (contralateral)

pain temperature

in Brown Sequard Syndrome, corticospinal tract lesions cause __ motor paralysis at the level of the lesion and __ motor paralysis below the lesion

level of the lesion: ipsilateral flacid below the lesion: ipsilateral spastic

flaccid paralysis is associated w. __ motor neuron lesion, spastic paralysis is associated w. __ motor neuron lesion

flaccid: lower spastic: upper