PHYSIOLOGY - nerve pathways Flashcards
what type of input does the superior colliculus receive
ocular input
what type of input does the inferior colliculus receive
auditory input
what does the dorsal column (DCML) supply
is it ascending (sensory) or descending (motor)
fine touch and proprioception (and 2 point discrimination)
ascending (sensory
what does the spinothalamic tract supply
is it ascending (sensory) or descending (motor)
pain, temperature, deep pressure
ascending (sensory)
what does the spinoreticular tract supply
is it ascending (sensory) or descending (motor)
pain (slower response than spinothalamic tract)
ascending (sensory)
what does the corticospinal tract supply
is it ascending (sensory) or descending (motor)
fine movements of distal limbs
descending (motor)
what does the tectospinal tract supply
is it ascending (sensory) or descending (motor)
head and neck movements in response to visual stimuli
descending (motor)
what does the vestibulospinal tract supply
is it ascending (sensory) or descending (motor)
balance and posture
descending (motor)
what does the reticulospinal tract supply
is it ascending (sensory) or descending (motor)
flexor/extensor movements
descending (motor)
what does the rubrospinal tract supply
is it ascending (sensory) or descending (motor)
excites flexor muscles and inhibits extensor muscles of upper body
descending (motor)
what are the 3 ascending (sensory) tracts
dorsal column - fine touch and proprioception
spinothalamic tract - pain, temperature, deep touch
spinoreticular tract - pain (slower)
what are the 5 descending (motor) tracts
corticospinal tract
tectospinal tract (head and neck movement in response to visual stimuli)
vestibulospinal tract (balance eand posture)
reticulospinal tract
rubrospinal tract
what are the 2 tracts within the dorsal column
medial fasciculus gracilis (gracile tract)
lateral fasciculus cuteatus (cuneate tract)
what does the medial fasciulus gracilis (gracile tract) part of dorsal column supply
lower limbs, T6 and below
THINK: the lateral nerves come off before the medial ones = medial ones supply lower down
what does the lateral fasciculus cuneate (cuneate tract) part of the dorsal column supply
upper limbs, above T6
THINK: lateral nerves comes off before the medial ones = lateral ones supply upper limbs
where do the fibres in the dorsal column dessucate (cross sides)
medulla
in the medulla, which nucleus does the fasciculus gracilis synapse at
gracile nucleus
in the medulla, which nucleus does the fasciculus cuneatus synapse at
cuneate nucleus
after they synapse in the medulla (cuneate/gracile nucleus) where do the second order neurons of the dorsal column travel
(arrive in thalamus)
in the medial lemniscus (band of white matter)
dorsal column
where are the first order neurones
between stimulus and medulla
dorsal column
where are the second order neurons
between medulla and thalamus
dorsal column
where are the third order neurons
between thalamus and primary somatosensory cortex in cerebrum
which gyrus is the primary somatosensory cortex in
post central gyrus (just behind the central sulcus)
which part of the somatosensory cortex is most medial (info from which part of the body)
feet
which part of the somatosensory cortex is most lateral (info from which part of the body)
head
what is the ‘man’ called that represents what the body would look like if each art was in proportion to its sensory input
homunculus
how would you test is the dorsal column was working or not (2)
fine touch
proprioception
what does the spinothalamic tract (STT) do
relays pain, temperature and deep pressure info to brain
where do the fibres dessucate (cross) in the STT
in the spinal cord
NOT medulla like the dorsal column
do dorsal column and STT fibers enter the spinal cord via white or grey matter
entire via grey matter
then travel up spinal cord in white matter
which spinal tract is also known as the pyramidal tract
corticospinal tract
which tract travels along side the corticospinal tract in the pyramids of the medulla to supply motor nerves to the face
corticobulbar tract
where do the fibres in the corticospinal tract originate
primary motor cortex
which gyrus is the primary motor cortex in
precentral gyrus
THINK: motor fibres want to get close to the action = more anterior gyrus
what % of fibres dessucate (cross) at the medulla in the corticospinal tract
what is this subtype of the tract called
85%
lateral corticospinal tract
what % of fibres dessucate (Cross) in the spinal cord in the corticospinal tract
what is this subtype of the tract called
15%
anterior corticospinal tract
where do the lateral corticospinal tract fibres dessucate
medulla
where do the anterior coritcospinal tract dessuctae
spinal cord
which spinal tract has bilateral supply
what is the clinical significance of this
corticobulbar (to the face)
UMN lesion = bilateral problem (though not complete paralysis bc of the other sided supply)
LMN lesion = unilateral problem (paralysis)
where do the fibres for the tectospinal tract originate
superior colliculus cortex
where does the sensory input for the tectospinal tract come from
occular input
tectospinal tract = moves head and neck in response to a visual stimuli
where does the fibres from the tectospinal tract leave the spinal cord
C1-C8
bc they supply the head/neck etc
what are the 2 origins of the 2 reticulospinal tracts
pons
medulla
where does the fibres form the vestibulospinal tract originate
vestibular nuclei (in pons)
where does the sensory input for the vestibulospinal tract come from
vestibular apparatus and cerebellum
bc it controls muscles of balance
is the supply of the vestibulospinal tract bilateral, ipsilateral or controlateral
ipsilateral
THINK: bc the cerebellum has ipsilateral control
where is the primary auditory cortex
superior temporal lobe, just under the lateral fissure
is it wernickes or brocas area that is near the primary auditory cortex in the superior temporal lobe (just under the lateral fissure)
wernickes
THINK: bc brocas = broken language, then wernickes must be unable to understand language = auditory processing problem
why does alcohol make you dizzy
alcohol is lighter than water = crystals more likely to sink = activates hair cells
in right handed people, which hemisphere is dominant for language (hence contains wernickes and brocas areas)
left hemisphere
which ascending tract recognises 2 point discrimination
dorsal column (probs bc it does proprioception)
which descending pathway is pyramidal
by default, what does that make the rest of them…
corticospinal tract
rest = extrapyramidal
