Ascending Sensory Systems Flashcards
5 ascending pathways
- posterior column-medial lemniscus pathway
- spinothalamic tract (anterolateral pathway)
- posterior spinocerebellar tract
- cuneocerebellar tract
- anterior spinocerebellar tract
ascending and descending pathways have well defined locations in spinal cord ____
white matter
different types of fibers of ascending/descending pathways
- long, ascending fibers going to thalamus, cerebellum, or various brainstem nuclei
- long, descending fibers from cerebral cortex or various brainstem nuclei to spinal cord gray matter
- short, propriospinal fibers interconnecting different spinal cord levels (help coordinate
ascending tracts found in:
all three funiculi (anterior, lateral, and posterior)
descending tracts primarily located in:
anterior and lateral funiculi
propriospinal fibers surround the spinal cord ____
gray matter (propriospinal tract)
detect mechanical, chemical, or thermal changes
somatosensory receptors
all somatosensory receptors are ____ neurons with cell body in _____ or ____
pseudounipolar; DRG; cranial nerve ganglion
pacinian corpuscle receptor for:
vibration
meissner corpuscle:
discriminative touch (two point discrimination)
ruffini ending:
pressure
endings around hairs:
touch
merkel endings (Me)
discriminative touch (two point disc, fine touch, texture)
free nerve endings
pain, temp, itch, touch
in the PC-ML pathway, cross the midline as _____ and form the ____; this occurs in the ____
internal arcuate fibers; medial lemniscus; caudal medulla
in the STT/anterolateral pathway, fibers cross the midline in the ____ of the ____
anterior commissure; spinal cord
in the STT/anterolateral pathway, collaterals are sent to the:
reticular formation in the caudal medulla; PAG in the rostral midbrain; hypothalamus
origin of the posterior spinocerebellar tract (PSCT)
Clarke’s nucleus in T1-L2/3
PSCT uses the ___ to enter the cerebellum
inferior cerebellar peduncle
origin of anterior spinocerebellar tract (ASCT)
spinal border cells (T12-L5)
ASCT fibers cross in the ____ and in the ____
spinal cord; cerebellum
cuneocerebellar tract (CCT) origin
lateral cuneate nucleus in the medulla
CCT enters the cerebellum through the _____
inferior cerebellar peduncle
ASCT enters the cerebellum through the _____
superior cerebellar peduncle
