Sensory Tract

Question 1

sensory pathways are similar to motor pathways in that both?

Answer 1

transfer information between the CNA and peripheral organs

• motor: superior to inferior
• sensory: inferior to superior

Question 2

both sensory and motor tracts rely on neurons in?

Answer 2

ganglia/nuclei and the cerebral cortex that send an impulse from one to the next

Question 3

In contrast to the motor pathway, sensory pathways?

Answer 3

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)

Question 4

dorsal column-medial lemniscus tract (DCML) function?

Answer 4

fine touch, proprioception, vibration, and pressure

Question 5

dorsal column-medial lemniscus tract (DCML) has how many neurons? Why do they go?

Answer 5

4+ neurons, 3 to get to cortex

*somatosensory cortex = post central gyrus

Question 6

ventral or posterioral rootlets are motor or sensory? (DCML)

Answer 6

ventral= motor
dorsal/posterior = sensory

Question 7

Order/path of 4 nuerons? (DCML)

Answer 7

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

Question 8

posterior funiculus = _____ column

Answer 8

dorsal column; sensory

Question 9

the axon of the 1st order neuron will synapse on the ?

(DCML)

Answer 9

ipsilateral dorsal column nuclei (nucleus gracilis and nucleus cuneatus)

Question 10

2nd order neuron (cell body in dorsal nuclei) projects their axons to the? (DCML)

Answer 10

contralateral side to ascend as the medial lemniscus

Question 11

medial lemniscus

Answer 11

fancy name for bundle of 2nd order neuron axons that crossed over
*will synapse on 3rd order neurons

Question 12

what is the thalamus?

Answer 12

big cluster of nuclei, which acts as the switchboard of sensory input to direct info to the sensosry cortex

Question 13

3rd order neurons found? (DCML)

Answer 13

in thalamus

Question 14

4th order neurons found in? (DCML)

Answer 14

somatosensory cortex (post-central gyrus)

Question 15

3rd order neuron ascends thru what to get to 4th? (DCML)

Answer 15

internal capsule to get to the cortex (so it’ll synapse on 4th order IN the sensory cortex)

Question 16

spinothalamic tract function?

Answer 16

pain and temperature

Question 17

spinothalamic tract cell body of 1st neuron is in?

Answer 17

the dorsal root ganglion (just like DCML)

Question 18

Unlike DCML, where the 1st neuron axon ascends all the way to the medulla to synapse… the spinothalamic tract 1st order synapses?

Answer 18

on the 2nd order neuron in the DORSAL HORN at the ENTRY LEVEL; enters from POSTERIOR direction

Question 19

in spinothalamic tract, when does the cross over happen?

Answer 19

in the DORSAL HORN at the ENTRY LEVEL where the 1st order synapse

Question 20

2nd order neurons found? (spinothalamic tract) first thing 2nd order does?

Answer 20

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

Question 21

what would a lesion to the 3rd or 4th neruon for either tract present as?

Answer 21

contralateral side b/c already crossed over

Question 22

what would a lesion to the spinothalamic tract present as?

Answer 22

loss of sensory info = contralateral side