19.7 NS: Peripheral sensory mechanisms

Question 1

What type of skin are the palmar surface of hands and the soles of feet covered by?

Answer 1

Glabrous skin

Question 2

What types of mechanoreceptors are found in glabrous skin (surface vs. deep)?

Which ones are more dense?

Answer 2

Surface: Meissner corpuscles, Merkel compleses (surface, high density)

Deeper: Ruffini organs, Pacinian corpuscles (deep, low density)

Question 3

What kinds of axons are the mechanorecptors in glabrous skin innervated by? Where are the cell bodies?

Answer 3

Large myelinated axons, bodies in the dorsal root ganglia

Question 4

What is the difference in the information that slowly adapting vs. rapidly adapting mechanoreceptors provide?

Answer 4

Slowly: steady, reflect duration of stimulus

Rapidly: concerned with change

Question 5

What mechanoreceptors have the smallest and largest receptive fields?

Answer 5

Smallest: Meissner
Largest: Pacinian

Question 6

Where are Merkel and Ruffini MR’s found? What do they respond to?

Answer 6

Merkel: found at tips of epidermal ridges (respond to indentation)

Ruffini: in upper dermis, sustained response to skin movement

Question 7

Where are Meissner and Pacinian MR’s found and what is do they respond to?

Answer 7

Meissner: near skin surface, transient response to skin movement

Pacinian: deep, transient response to vibration

Question 8

How do tactile vs. nociceptive primary sensory afferents respond to a stimuli?

Answer 8

Tactile: firing at steady rate while stimulus is applied

Nociceptive: firing rate increases with temperature

Question 9

So in a manipulation tasks, what do:
Meissner
Merkel 
Pacinian
Ruffini

mechanoreceptors encode for?

Answer 9

Meissner: rate of force
Merkel: grip force
Pacinian: vibrations
Ruffini: hand posture

Question 10

Does hairy or glabrous skin have better spatial resolution?

Answer 10

Lower spatial resolution on hairy skin