Ascending Sensory Systems

Question 1

5 ascending pathways

Answer 1

1. posterior column-medial lemniscus pathway
2. spinothalamic tract (anterolateral pathway)
3. posterior spinocerebellar tract
4. cuneocerebellar tract
5. anterior spinocerebellar tract

Question 2

ascending and descending pathways have well defined locations in spinal cord ____

Answer 2

white matter

Question 3

different types of fibers of ascending/descending pathways

Answer 3

1. long, ascending fibers going to thalamus, cerebellum, or various brainstem nuclei
2. long, descending fibers from cerebral cortex or various brainstem nuclei to spinal cord gray matter
3. short, propriospinal fibers interconnecting different spinal cord levels (help coordinate

Question 4

ascending tracts found in:

Answer 4

all three funiculi (anterior, lateral, and posterior)

Question 5

descending tracts primarily located in:

Answer 5

anterior and lateral funiculi

Question 6

propriospinal fibers surround the spinal cord ____

Answer 6

gray matter (propriospinal tract)

Question 7

detect mechanical, chemical, or thermal changes

Answer 7

somatosensory receptors

Question 8

all somatosensory receptors are ____ neurons with cell body in _____ or ____

Answer 8

pseudounipolar; DRG; cranial nerve ganglion

Question 9

pacinian corpuscle receptor for:

Answer 9

vibration

Question 10

meissner corpuscle:

Answer 10

discriminative touch (two point discrimination)

Question 11

ruffini ending:

Answer 11

pressure

Question 12

endings around hairs:

Answer 12

touch

Question 13

merkel endings (Me)

Answer 13

discriminative touch (two point disc, fine touch, texture)

Question 14

free nerve endings

Answer 14

pain, temp, itch, touch

Question 15

in the PC-ML pathway, cross the midline as _____ and form the ____; this occurs in the ____

Answer 15

internal arcuate fibers; medial lemniscus; caudal medulla

Question 16

in the STT/anterolateral pathway, fibers cross the midline in the ____ of the ____

Answer 16

anterior commissure; spinal cord

Question 17

in the STT/anterolateral pathway, collaterals are sent to the:

Answer 17

reticular formation in the caudal medulla; PAG in the rostral midbrain; hypothalamus

Question 18

origin of the posterior spinocerebellar tract (PSCT)

Answer 18

Clarke’s nucleus in T1-L2/3

Question 19

PSCT uses the ___ to enter the cerebellum

Answer 19

inferior cerebellar peduncle

Question 20

origin of anterior spinocerebellar tract (ASCT)

Answer 20

spinal border cells (T12-L5)

Question 21

ASCT fibers cross in the ____ and in the ____

Answer 21

spinal cord; cerebellum

Question 22

cuneocerebellar tract (CCT) origin

Answer 22

lateral cuneate nucleus in the medulla

Question 23

CCT enters the cerebellum through the _____

Answer 23

inferior cerebellar peduncle

Question 24

ASCT enters the cerebellum through the _____

Answer 24

superior cerebellar peduncle