Touch & Proprioception

Question 1

system concerned with light touch and pressure (2 point discrimination, vibration) and proprioception/position sense

Answer 1

posterior column/medial lemniscus

Question 2

examples of touch and pressure receptors

Answer 2

meissner’s corpuscle (touch), pacinian corpuscle (pressure), Merkel’s disc and Ruffini’s ending

Question 3

proprioception receptors that allow us to perceive body position and movement, picking up information about where a joint is

Answer 3

muscles spindles and Golgi tendon organs (GTOs)

Question 4

touch and pressure ascend to the cortex through what pathway?

Answer 4

posterior column medial lemniscus

Question 5

what fibers are responsible for touch and pressure?

Answer 5

A-beta

Question 6

which fibers are responsible for proprioception?

Answer 6

A-alpha

Question 7

what does the dorsal column refer to?

Answer 7

spinal cord

Question 8

what does the medial lemniscus refer to?

Answer 8

the brainstem

Question 9

At T6 & above, which fascicules is present?

Answer 9

fascicules gracilis (medial) & fascicules cuneatus (lateral)

Question 10

At T7 & below which fascicules is present?

Answer 10

fascicules gracilis only

Question 11

At L2/C5, where do the primary afferent fibers ascend through?

Answer 11

L2: ascends through fasciculis gracilis to nucleus gracilis
C5: ascends to the fasciculis cuneatus to the nucleus cuneatus

Question 12

where in the SC do the primary afferent fibers ascend in the PCMLP?

Answer 12

dorsal/posterior part of the SC

Question 13

which fibers in the PCMLP are responsible for touch and pressure?

Answer 13

A beta fibers

Question 14

which fibers are responsible for proprioception in the PCMLP?

Answer 14

A alpha fibers

Question 15

where do the primary afferent fibers synapse once passing through the fascicules gracilis/cuneatus?

Answer 15

in the nucleus gracilis/cuneatus

Question 16

what makes up the posterior/dorsal column to the spinal cord?

Answer 16

fasciculis gracilis + fasciculis cuneatus

Question 17

before the SON cross midline at the AWC, what are they called once they get to the nucleus G/C?

Answer 17

internal arcuate fibers

Question 18

after the SON cross midline at the AWC, what do the SON axons form ascending to the thalamus (VPL)?

Answer 18

medial lemniscus

Question 19

where is the soma of the TON in the PCMLP located

Answer 19

VPL

Question 20

axons of TON of the PCMLP project axons from (?) to (?)

Answer 20

thalamus (VPL) to primary somatosensory cortex

Question 21

because of the homunculus, fibers representing LEs course (?) while fibers representing UE course (?)

Answer 21

1. LE - medially

2. UE - laterally

Question 22

which medulla are the nucleus gracilis/cuneatus located?

Answer 22

caudal medulla

Question 23

putting pressure (or vibrations) on an area that’s been injured - nociceptive pathways (holding it A-beta fibers), utilizing sensations to block pain is known as what?

Answer 23

gate control theory

Question 24

excites a population of enkephalin containing interneurons in lamina II (because interneurons can be found in the SG)

Answer 24

A-beta fibers

Question 25

what happens when enkephalin is released onto the C and A delta fiber terminals?

Answer 25

it inhibits the primary afferent nociceptive fibers from releasing their neurotransmitters

Question 26

what happens when the neurotransmitters of the A-delta and C fibers are inhibited?

Answer 26

interference of nociceptive info passed from FON to SON = less nociceptive info passed to the cortex, trying to “close the gate on pain”

Question 27

where does proprioceptive information reach?

Answer 27

cerebellum

Question 28

why is proprioceptive information important?

Answer 28

control of motor movements

Question 29

what happens without proprioception?

Answer 29

inability to manage body (planned and coordinated movements)