Lab 6 Structures Flashcards
label
medial division fibers
- large fiber afferents
- heavily myelinated
- vibration, joint position sense, discriminative touch
- enters spinal cord through dorsal white matter funiculus
lateral division fibers
- small fiber afferents
- lightly/non-myelinated
- pain/temperature
- enters spinal cord via Lissauer’s tract and then dorsal horn gray matter
what are the 2 ascending sensory tracts that are 3 neuron pathways?
- dorsal column medial lemniscal tract (DCML)
- spinothalamic tract (SPTH) contained within anterolateral system (ALS)
what is the function of the dorsal column medial lemniscal tract?
carries ascending somatosensory info regarding vibration, joint position, discriminative touch from body to cerebral cortex
origin of 1st ordered neuron
DCML
periphery sensory receptors (Merkel disc, Pacinian corpuscle, Meissner corpuscle)
pseudo-unipolar
division of dorsal root for 1st ordered neuron
DCML
medial
where does 1st ordered neuron enter spinal cord?
DCML
dorsal white matter
where does 1st ordered neuron travel?
DCML
- ascends via dorsal columns
- gracile fasciculi (LE is medial)
- cuneate fasciculi (UE is lateral)
where does 1st ordered neuron synapse?
DCML
- synapses in dorsal column nuclei
- gracile/cuneate tubercles in caudal medulla
origin of 2nd ordered neuron
DCML
dorsal column nuclei (gracile/cuneate tubercles)
where does 2nd ordered neuron travel?
DCML
crosses at level of nuclei and ascends as combined bundles of white matter fibers (medial lemniscus) to thalamus
where does 2nd ordered neuron synapse?
DCML
synapses in ventral posterior lateral (VPL) nucleus of thalamus
origin of 3rd ordered neuron
DCML
VPL of thalamus
where does 3rd ordered neuron travel?
DCML
- exits VPL of thalamus
- enters posterior limb of internal capsule
- travels to cerebral white matter
where does 3rd ordered neuron synapse?
DCML
terminates in cerebral cortex (post central gyrus)
what is the function of the spinothalamic tract?
carries ascending sensory info regarding pain/temperature from body to cerebral cortex
origin of 1st ordered neuron
SPTH
peripheral sensory receptors (nociceptors)
division of dorsal root for 1st ordered neuron
SPTH
lateral
where does 1st ordered neuron enter spinal cord?
SPTH
- Lissauer’s tract
- ascends 1-2 levels
- synapses in gray matter of dorsal horn of spinal cord
where does 1st ordered neuron travel?
SPTH
ascends 1-2 levels within Lissauer’s tract before entering spinal cord gray matter to synapse
where does 1st ordered neuron synapse?
SPTH
synapses in gray matter of dorsal horn of spinal cord
origin of 2nd ordered neuron
SPTH
dorsal horn gray matter of spinal cord
where does 2nd ordered neuron travel?
SPTH
crosses spinal cord via ventral white commissure to join contralateral white matter bundle (ALS/SPTH) and then ascends to VPL of thalamus
where does 2nd ordered neuron synapse?
SPTH
synapses in VPL of thalamus
origin of 3rd ordered neuron
SPTH
VPL of thalamus
where does 3rd ordered neuron travel?
SPTH
exits VPL of thalamus and enters posterior limb of internal capsule and ascends to cerebral white matter
where does 3rd ordered neuron synapse?
SPTH
terminates in cerebral cortex (post central gyrus) and widespread cortical areas
what are the 3 ascending sensory tracts that are 2 neuron pathways?
- dorsal spinocerebellar tract (DSCT)
- cuneocerebellar tract (CCT)
- ventral spinocerebellar tract (VSCT)
what is the function of the dorsal spinocerebellar tract?
muscle spindle info about LE
origin of 1st ordered neuron
DSCT
muscle spindles of trunk/LE
division of dorsal root for 1st ordered neuron
DSCT
medial