Cranial Nerves and Corticospinal Tract Flashcards
afferent and efferent limbs of pupillary light reflex
afferent: CN II
efferent: CN III
afferent and efferent limbs of eye accommodation
afferent: CN II
efferent: CN III
eye accommodation:
afferent limb:
efferent limb:
afferent: CN II → optic
efferent: CN III → oculomotor
what n controls movement of superior oblique m
CN IV
what extrinsic eye muscles does CN III innervate (5)
superior rectus
medial rectus
inferior rectus
inferior oblique
levator palpebrae
motor fxn of CN IV (trochlear)
intort, abduction → reading book and walking downstairs
CN IV (trochlear) is vulnerable to __ injury
shear
motor fxn of CN V
biting/chewing/mastication
V1 is same-same
ophthalmic
V2 is same-same
maxillary
V3 is same-same
mandibular
PSNS motor fxn of V2 (maxillary)
lacrimal gland/nose secretions
sensory fxn of CN V
sensation to face, mouth, nose, eyes
afferent and efferent limbs of the corneal (blink) reflex
afferent: Vi (ophthalmic)
efferent: CN VII → orbicularis oculi
pathway of corneal (blink reflex)
V1 sense stimulus on cornea (afferent) → brainstem → CN VII (efferent) initiates motor response on both sides via orbicularis oculi
motor fxn of V3
mastication
afferent and efferent limbs of jaw jerk reflex
V3
PSNS fxn of V3
submandibular/sublingual gland secretions
sensation (not taste) to anterior ⅔ of tongue
V3
motor fxn of CN VI
abduction of eye → outward gaze
what m does CN VI innervate
lateral rectus
special sensory fxn of CN VII
taste to anterior ⅔ of tongue
motor fxn of CN VII
muscles of facial expression
dampening of sound in ear
PSNS fxn of CN VII
lacrimal gland
submandibular gland
efferent blink reflex
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
