sensory and motor pathways in the CNS Flashcards
how are sensory pathways organised
somatically
what is the trigeminal sensory pathway made up of
primary sensory neruone
second order
third order
where is the primary sensory neurone found in the trigenmial
receptor to sensory or spinal nucleus
where is the second order neurone found in the trigenmial
trigeminal nucleus to VPM nucleus of thalamus
where is the third order neurone found in the trigenmial
VPM nucleus in thalamus to cortex (post central gyrus)
where is the spinal trigeminal nucleus found
medulla
what are motor pathways split into
upper motor neurone
lower motor neurone
where does the lower motor neurone go from and to
brainstem or SC to muscle
what defines upper motor neurones
any neurones carrying info within the CNS making up motor pathways
what s the distinction of lower motor nruoens
neurones conveying motor infro from brainstem or SC to muscle
where is the cell body of lower motor neurones found
ventral horn of SC
where can lower motor neurones received info from
direct/indirect corticospinal pathways
tectospinal pathways
vestibular pathways
where of upper motor neurones cross to
contralateral side
what makes up the basal ganglis
large nuclei of grey matter in the cerebral hemispheres (and substantial nigra)
what do basal ganglia do
connect sensory ares to motor areas via loop systems
suppress unwanted movement/amplify intended movement
what does damage of basal ganglia do
abnormal movement (dyskinesia)
Parkinsons
chorea
effect of lower motor injurt
no signal to muscle - flaccid paralysis
if no regeneration: atrophy or contracture
effect of upper motor injury
still source of info to muscle
input not modified by the brain
leads to: spastic paralysis or hyperreflexia
describe sensory pathways
3 neurone chain, primary neurone second and third order
what are the two different sensory pathways
spinothalamic (pain/temp) medial leminsical (proprioception)
describe the spinothalamic pathway
afferent fibre in
synapse in the dorsal horn of SC
crosses and accends in the spinothalamic tract to thalamus
thalamus to cerbral cortex
describe the medial leminiscal pathway
afferent fibre in
ascends in the SC to the cuneatus and gracile nuclei in medulla (brainstem)
synapse and cross
travel in medial lemunicus tract to thalamus
thalamus to cerebral cortex (post central gyrus)
what is the difference in the medial leminscus pathways
nuclei where it synapses dependant on where input tp body enters
where is the spinal nucleus
medulla
where is the main sensory nucleus
middle of spinal nucleus
where are the cell bodies of the trigeminal pathway found
trigeminal ganglion
where are cell bodies of fibres from PDL or jaw
CNS
what types of input will go to the main sensory nucleus in the trigeminal pathway
low threshold afferents i.e. touch
what types of input will go to the spinal nucleus in the trigeminla pathway
high threshold afferent i.e. pain
explain the trigeminal sensory pathway
primary sensory neurone
afferent fibres to either spinal nucleus (pain) or main sensory nucleus (touch) (trigeminal nucleus) synapse and
decussate and go up to thalamus (VPM nucleus)
third order - from VPM to post central gyrus via internal capsule
similarities between sensory and trigeminal pathway
3 neurone pathway
both reach thalamus and cortex
what do injures to upper motor neurones affect
contralateral side
trigeminal nerves go where depending on pain and touch
pain: spinla nucleus
touch: main sensory nucleus
