Lec 6 Somatic Sensory

Question 1

Encapsulated receptors: myelinated or unmyelinated? Detects what stimuli?

Answer 1

myelinated

mechanical

Question 2

Free Nerve Endings: myelinated or unmyelinated? Detects what stimuli?

Answer 2

Unmyelinated

pain/temp

Question 3

First step in all sensory processes

Answer 3

Sensory transduction: energy from stimulus converts to electrical signal (AP)

Question 4

Rapidly Adapting (AKA Phasic) Receptors

Answer 4

only respond to on/offset.

info about change/dynamic quality.

Question 5

Slowly Adapting (AKA Tonic) Receptors

Answer 5

continous AP firing as long as stimulus present.

info about persistence/static quality.

Question 6

Which mechanoreceptors are Rapidly-Adapting?

Answer 6

Meissner

Pacinian

Question 7

Which mechanoreceptors are Slowly-Adapting?

Answer 7

Merkel

Ruffini

Question 8

Meissner detects…

Answer 8

low-freq vibration.

tactile discrimination.

Question 9

Pacinian detects…

Answer 9

high-freq vibration.

deep pressure

Question 10

merkel detects

Answer 10

light pressure

Question 11

ruffini detects

Answer 11

cutaneous stretch during digital movement

Question 12

2-pt discrimination

Answer 12

ability to perceive 2 stimuli as distinct points

Question 13

more receptors = ____ (higher/lower) 2-pt discrimination

Answer 13

lower

Question 14

receptive fields

Answer 14

region of skin within which tactile stimulation evokes a response in axon

Question 15

more receptors = ____ (larger/smaller) receptive field

Answer 15

smaller

Question 16

Muscle spindle: intrafusal fibers

Answer 16

inside capsule

Question 17

Muscle spindle: Nuclear Bag Fiber

Answer 17

largest intrafusal

nuclei centered

Question 18

Muscle spindle: Nuclear Chain Fiber

Answer 18

remaining fibers, nuclei lined up single-file

Question 19

Muscle spindle: primary sensory ending

Answer 19

group 1a myelinated axons that invx both types of fibers

Question 20

Muscle spindle: secondary innervation

Answer 20

group 2 axons - invx chain & give off branches to bag

Question 21

Muscle spindle: gamma motor neurons

Answer 21

causes spindle to contract

Question 22

Larger muscles = ____ (higher/lower) density of spindles

Answer 22

lower

Question 23

Trigeminal Nerve sensory branches

Answer 23

V1 - Opthalamic - sensation btwn eyes/forehead.
V2 - Maxillary - sensation btwn eyes/mouth.
V3 - Mandibular - sensation to mandibular region.

Question 24

Trigeminal Complex components

Answer 24

Principle Sensory Nucleus (mechanosensory).
Spinal Nucleus (pain/temp).

Question 25

VPL receives projections from…

Answer 25

body

Question 26

VPM receives projections from…

Answer 26

face

Question 27

Axons from thalamus project to…

Answer 27

Layer 4 of somatosensory

Question 28

Primary sensory cortex: Broadman’s 3a responds to

Answer 28

muscle stretch

Question 29

Primary sensory cortex: Broadman’s 3b responds to

Answer 29

tactile

Question 30

Primary sensory cortex: Broadman’s 1 responds to

Answer 30

texture

Question 31

Primary sensory cortex: Broadman’s 2 responds to

Answer 31

shape/size

Question 32

Broadman’s 3b projects to…

Answer 32

Broadman’s 1 & 2

Question 33

Primary Sensory projects to

Answer 33

Secondary Sensory
Motor Cortex (Area 4)
Other association cortices (Areas 5 & 7)

Question 34

Secondarry Sensory projects to

Answer 34

amygdala & hippocampus

Question 35

Why are descending axons > ascending?

Answer 35

limits incoming sensory info, prevents CNS from being overloaded.