Physiology 4: Somatosensory System

Question 1

the top of the postcentral gyrus provides sensory information to…

Answer 1

the toes

Question 2

how many layers does the somatosensory cortex have?

Answer 2

6

Question 3

S1 refers to..

Answer 3

the central sulcus

Question 4

S2 refers to…

Answer 4

posterior parietal cortex

Question 5

there is only 1 somatotopic map of the body in the sensory cortex T or F

Answer 5

F there are multiple

Question 6

what happens to an area of the sensory cortex eg for finger if it’s counterpart isnt used anymore eg by amputation?

Answer 6

utilised by other sensory inputs

Question 7

what does the posterior parietal cortex do?

Answer 7

receives and integrates info from S1 and other cortexes eg visual as well aas the thalamus

Question 8

decussation (crossing) of the DCML pathway occurs where?

Answer 8

brainstem

Question 9

decussation (crossing) of the spinothalamic tract occurs where?

Answer 9

at the respective level of the spinal cord to the other side

Question 10

which pathway is in charge of sensation of discriminatory touch, pressure, vibration, conscious proprioception

Answer 10

DCML

Question 11

which pathway is in charge of sensations of pain, temp, crude touch, itch and tickling?

Answer 11

spinothalamic

Question 12

name the 2 tracts of the dorsal column of the spinal cord from medial to lateral

Answer 12

fasciculus gracilis

fasciculus cuneatus

Question 13

sensory input to T6 and below travels in what tract of the dorsal column?

Answer 13

fasciculus gracilis

Question 14

sensory input above T6 level travels in what tract of the dorsal column?

Answer 14

fasciculus cuneatus

Question 15

axons travelling via the DCML pathway from T6 and below will synapse where first?

Answer 15

dorsal column gracile nucleus

Question 16

axons travelling via the DCML pathway from T5 and up will synapse where first?

Answer 16

dorsal column cuneate nucleus

Question 17

3rd order neurones from the thalamus in the DCML pathway travel via what to get to the postcentral gyrus?

Answer 17

posterior internal capsule

Question 18

define lateral inhibition

Answer 18

when one neurone is active it inhibits the activity of its neighbours using inhibitory interneurons

Question 19

why does lateral inhibition exist?

Answer 19

sharpens stimulus perception

Question 20

name the 2 main sensory tracts

Answer 20

spinothalamic

DCML