Ascending Systems 2 Flashcards
sensory first order neuron location
peripheral process and DRG in PNS
central process enters cord
sensory first order synapse location
cord or brainstem
sensory second order neuron synapse
ventral posterolateral thalamus
sensory third order neuron synapse
cortex
location of sensory decussation
at the gracilis or cuneate nuclei
DCML does
discriminatory touch
position
vibration
location of second order synapse above T6
cuneate fasiculus
location of second order synapse below T6
gracilis fasiculus
in what do the fibers decusate
internal arcuate fibers
what forms medial lemniscus
internal arcuate fibers from the gracilis/cuneate nuclei
in what do fibers travel from the VPL to the cortex
posterior limb of the internal capsule
what is the post synaptic dorsal column system
alternate route of DCML information- fibers synapse immediately upon entering cord
for pain sensation
medial division of the dorsal root entry zone
large heavily myelinated fibers
synapse at laminae III-V
lateral division of the dorsal root entry zone
small axons with little to no myelination
join Lissauer’s tract
somatotrophic arrangement of medial lemniscus
legs are most anterior
trunk
arms more posterior
DCML blood supply
posterior spinal arteries
defect of peripheral nerve damage
loss of all modalities in the nerve field distribution
defect of dorsal root damage
loss of all modalities in the dermatome distribution
defect in the CNS
depends on the lesion location as to what side affected and severity
modality
type of sensation
topography
where
level of sensation
quality
DCML defect results in
full loss of vibratory sensation
partial loss of everything else (covered by other systems)
romberg sign
difficult standing with eyes close
common cause of ataxia
loss of proprioception in feet
Frederich’s ataxia
autosomal reessive mutation affecting the DCML
tabes dorsalis
associated with late stage neurosyphallis
ataxia
lack of muscle movement coordination
