somesthesis (14)

Question 1

what are the two categories that tactile receptors can be divided into?

Answer 1

• slowly adapting mechanoreceptors

- rapidly adapting mechanoreceptors

Question 2

does this statement describe slowly or rapidly adapting mechanoreceptors?
“ big initial burst then maintaining the stimulus over time”

Answer 2

slowly adapting

Question 3

are meissner’s corpuscles rapidly or slowing adapting?

Answer 3

rapidly

Question 4

where are meissner’s corpuscles located

Answer 4

in the superficial layers of the skin

tend to be in areas of high sensitivity (finger tips, lips)

Question 5

are merkel receptors rapidly or slowing adapting?

Answer 5

slow adapting

Question 6

what are merkel receptors?

Answer 6

a number of diff individual receptors innervated by the same axon

Question 7

where are merkel’s receptors?

Answer 7

tend to areas of high sensitivity (lips, finger tips)

Question 8

where are ruffini’s end organs?

Answer 8

tend to be in deeper tissues

also in deep layers of the skin

Question 9

describe ruffini’s end organs

Answer 9

receptors that are multibranched, encapsulated nerve endings that adapt very little

Question 10

are pacinian corpuscles rapidly or slowing adapting?

Answer 10

rapidly adapting

Question 11

where are pacinian corpuscles found?

Answer 11

found in deep tissue & immediately below the skin

Question 12

what is one function that pacinian corpuscles are important for?

Answer 12

imp for vibration

Question 13

define a receptive field

Answer 13

portion of the skin directly innervated by the receptor terminals and the area of adjacent tissue through which a stimulus can be conducted to the receptor

Question 14

describe the relationship between receptor density and receptor field size

Answer 14

inverse relationship

Question 15

what are the two major parallel systems that carry somatosensory info tot he cerebral cortex?

Answer 15

1. dorsal column lemniscal system

2. anterolateral system

Question 16

what is the dorsal column lemniscal system important for?

Answer 16

carrying high tactile info and spatial discrimination

Question 17

what is the anterolateral system important for?

Answer 17

Carries info chiefly about pain & temp

Question 18

where does the first segregation of sensory information begin?

Answer 18

at the end of the spinal cord

Question 19

describe the path of nerve fibers entering the dorsal column

Answer 19

Nerve fibers entering the dorsal columns pass up these columns on the ipsilateral side to the caudal medulla where they synapse in the dorsal column nuclei (the cuneate & gracile nuclei)

Question 20

where do fibers of the medial lemnicus synapse?

Answer 20

they synapse on the ventral posterior nucleus of the thalamus

Question 21

what two categories can the ventral posterior nucleus be divided into

Answer 21

• medial view

- lateral view

Question 22

medial view of the ventral posterior nucleus of the thalamus:
describe what type of information and where it projects that information to

Answer 22

information from head/neck/face

projects info most laterally in the postcentral gyrus

Question 23

lateral view of the ventral posterior nucleus of the thalamus:
describe what type of information and where it projects that information to

Answer 23

information from trunk & limbs

projects info most medially in the postcenral gyrus

Question 24

what are the 4 areas that S1 can be divided into

Answer 24

brodman’s area 3a, 3b, 1 and 2

Question 25

where do most of the thalamic fibers terminate in?

Answer 25

areas 3a and 3b

Question 26

where do cells in 3a and 3b project to?

Answer 26

areas 1 and 2

Question 27

what does area 3a mainly respond to?

Answer 27

deep tissue input

Question 28

what does area 3b primarily respond to?

Answer 28

to the activation of rapidly or slowing adapting cutaenous receptors

Question 29

what does area 2 primarily respond to?

Answer 29

to deep pressure

Question 30

what does area 1 primarily respond to?

Answer 30

activation of rapidly adapting cutaneous receptors

Question 31

where are most direction sensitive neurons found

Answer 31

found in area 1 and more notably in area 2 (NOT found in 3a or 3b)

Question 32

what does it mean if a neuron is direction sensitive?

Answer 32

the cell will only respond when a stimulus moves across the skin in a particular direction