Sensory Tract Flashcards
sensory pathways are similar to motor pathways in that both?
transfer information between the CNA and peripheral organs
- motor: superior to inferior
- sensory: inferior to superior
both sensory and motor tracts rely on neurons in?
ganglia/nuclei and the cerebral cortex that send an impulse from one to the next
In contrast to the motor pathway, sensory pathways?
1) carry inforamtion from the periphery INTO the CNA
2) terminate on neirons in the POST-central gyrus
3) consist of FOUR neurons in a chain (motor had 2)
4) ASCEND, relay though the thalamus (except olfactory)
dorsal column-medial lemniscus tract (DCML) function?
fine touch, proprioception, vibration, and pressure
dorsal column-medial lemniscus tract (DCML) has how many neurons? Why do they go?
4+ neurons, 3 to get to cortex
*somatosensory cortex = post central gyrus
ventral or posterioral rootlets are motor or sensory? (DCML)
ventral= motor dorsal/posterior = sensory
Order/path of 4 nuerons? (DCML)
1) 1st neuron is peripheral process sensory receptors (cell body and dorsal root ganglia)
- -central process enters into posterior horn
- -shortcut to dorsal columns
- -ascends in the ipsilateral posterior funiculus all the way to brainstem
- -synapses in nuclei
2) 2nd neuron crosses to other side
- -medial lemniscus
- -goes up to thalamus (brainstem)
3) 3rd passes through internal capsule
- -goes to cortex
4) 4th in cortex; end point
posterior funiculus = _____ column
dorsal column; sensory
the axon of the 1st order neuron will synapse on the ?
(DCML)
ipsilateral dorsal column nuclei (nucleus gracilis and nucleus cuneatus)
2nd order neuron (cell body in dorsal nuclei) projects their axons to the? (DCML)
contralateral side to ascend as the medial lemniscus
medial lemniscus
fancy name for bundle of 2nd order neuron axons that crossed over
*will synapse on 3rd order neurons
what is the thalamus?
big cluster of nuclei, which acts as the switchboard of sensory input to direct info to the sensosry cortex
3rd order neurons found? (DCML)
in thalamus
4th order neurons found in? (DCML)
somatosensory cortex (post-central gyrus)
3rd order neuron ascends thru what to get to 4th? (DCML)
internal capsule to get to the cortex (so it’ll synapse on 4th order IN the sensory cortex)
spinothalamic tract function?
pain and temperature
spinothalamic tract cell body of 1st neuron is in?
the dorsal root ganglion (just like DCML)
Unlike DCML, where the 1st neuron axon ascends all the way to the medulla to synapse… the spinothalamic tract 1st order synapses?
on the 2nd order neuron in the DORSAL HORN at the ENTRY LEVEL; enters from POSTERIOR direction
in spinothalamic tract, when does the cross over happen?
in the DORSAL HORN at the ENTRY LEVEL where the 1st order synapse
2nd order neurons found? (spinothalamic tract) first thing 2nd order does?
cell body in dorsal horn
*projects its axon to the contralateral side where it will then ascend all the way to the thalamus (3rd order) as the anterior and lateral spinothalamic tract
what would a lesion to the 3rd or 4th neruon for either tract present as?
contralateral side b/c already crossed over
what would a lesion to the spinothalamic tract present as?
loss of sensory info = contralateral side
