Chapter 4 and 5: Somatic Sensation

Question 1

touch and pain position sense are mediated by the?

Answer 1

dorsal column medial lemniscal pathway

Question 2

after a lesion of the DCML pathway discriminative capabilities are _______

and would have difficulty ______ with eyes closed because ________

give example

Answer 2

reduced

maintaining balance, reduced leg position sense

example:
- may not be able to distinguish rough and smooth ie. like grades of sandpaper

Question 3

what remains after dorsal column lesion

Answer 3

crude touch

Question 4

_______ a specialized kinda of f dorsal root ganglion neuron that provides major sensory input to the DCML system

Answer 4

mechanoreceptors

Question 5

limb position sense are sensitive to ____________

Answer 5

muscle stretch (muscle spindles)
tendon tension (GTO)

Question 6

what are examples of mechanoreceptors

Answer 6

1. ruffini’s corpuscles - Deep, SLOW
   - sensitive to skin stretch
   - discrimination
2. Meissner Corpuscles - Superficial, RAPID
   - ie. reading braille
3. merkels receptors - Superficial, SLOW
   - ie. reading braille
4. Pacinian Corpuscles -Deep, RAPID
   - most sensitive
   - sensitive to skin stretch
   - discrimination

Question 7

The principal receptor for proprioception is ______________ which is located within the _______

Answer 7

the muscle spindle receptor

muscle belly

Question 8

muscle spindle receptors provide information to the brain for

Answer 8

limb proprioception, spacial awareness of limbs

Question 9

GTO can have a role in an individuals sense of

Answer 9

how much effort it takes to produce a motor act

Question 10

how many sensory dermatomes are in the spinal cord?

Answer 10

31 sensory dermatomes

Question 11

-

Answer 11

• for somatic maping
• important for depicting lesions in the spinal cord

Question 12

the areas of the skin innervated by the axons in a single dorsal root is termed

Answer 12

dermatomes

Question 13

the spinal cord has a ______ organization

Answer 13

dorsoventral sensory motor organization

Question 14

the anterolateral system is for?

Answer 14

pain, temp and itch

Question 15

decussation of the DCML is where

Answer 15

medulla then the fibres ascend in the ventral part of the medial lemniscus

Question 16

the primary somatic sensory cortex has a _________ organizarion

Answer 16

columnar organization

Question 17

thalamus usually projects to cortical layer

Answer 17

4th layer

Question 18

neurons whose cell bodies are located in layers ____ and ______ project to other cortical areas

Answer 18

2 and 3

Question 19

callosal neurons are located in what layers

Answer 19

2 and 3

Question 20

corticocortical association neurons are in what later

Answer 20

2 and 3

Question 21

descending projection neurons are located in what layers

Answer 21

5 and 6

Question 22

BA (brodmann area)

3a and 2 :
3b and 1:

Answer 22

3a and 2 (both deep and skin) :
- deep
perception of body movement
(muscle, joint, and pressure sensations)
3b and 1:
- skin
touch

Question 23

there are 3 major projection streams for processing mechanosensation for primary somatic sensory cortex

describe there uses

1.

2.

3.

Answer 23

1. ventral : recognizing manipulated objects
2. dorsal: localization of objects and spatialization
3. rostral: movement control

Question 24

*
what is unique to our protective senses?

Answer 24

that they engage areas of the cerebral cortex that a for emotional sensation

Question 25

*
pain, temperature and itch are mediated by the _________

Answer 25

anterolateral system

Question 26

the anterolateral system, is a collection of ___ pathways that travel in the ______portion if the ______column of the spinal cord

Answer 26

ascending
anterior
lateral

Question 27

surgical destruction of the anterolateral system spares?

also,____

Answer 27

touch
limb position

people become less sensitive to pain

Question 28

the anterolateral systems first relay is ?

Answer 28

in the dorsal horn

Question 29

decussation of anterolateral system?

Answer 29

spinal cord level

Question 30

the spinothalamic projection to the VPL nucleus transmits info to the

Answer 30

primary somatic sensory cortex

Question 31

the ______i also importat for perception of pain quality

Question 32

the spinoreticular tract relay is?

Answer 32

parabrachial nucleus –> targets amygdala

Question 33

together the insular cortex and amygdala helps organize our

Answer 33

behavioural response that accompanies pain

• increase BP
• Rubbing injured site

Question 34

the spinoreticular tract engages a subcortical _.

Answer 34

emotion pathway

Question 35

the spinomescenphalic tract terminates in the _______

Answer 35

midbrain tectum

Question 36

spinomescenphalic tract:

• projection to the tectum integrates somatic sensory information with

Answer 36

vision
hearing
head orientation

Question 37

visceral pain is mediated by what?

Answer 37

dorsal horns whose axons who ascend in the dorsal columns

Question 38

true or false visceral pain takes the same pathway (mechanosensory pathway)

Answer 38

false;
- visceral pain neurons send axons into medial portion of the dorsal columns (gracille)

• visceral pain synapses in seperate portion of the dorsal column nuclei and thalamus than the mechanosensory pathwat

Question 39

itch sensitive receptors respond to ____ and are also called ______

Answer 39

• histamine
• pruriceptors

Question 40

three principle classes of nociceptor

Answer 40

thermal –> temp activated
mechanical –> tissue damaged activated
polymodal –> noxious, thermal, mechanical stimuli

Question 41

small diameter sensory firbes terminate primarily in the _________ of the dorsal horn

Answer 41

superficial laminae

Question 42

pain, itch, and temp enter the spinal cord through and in

Answer 42

lissauer tract (white mater region that caps the dorsal horn)

this stains lightly because the axons are not heavly mylenated

Question 43

laminae 1 and 2 receive info from

Answer 43

small- diameter myelinated and unmyelinated (c) fibres only

indicating a selective roll in pain, temp, and itch processing

Question 44

laminae 3 (III) and 4 (IV) receive info from

Answer 44

large - diameter fibres

processing a broad range of somatic stimulis intsities

Question 45

laminae 6-9 (VI-IX)

Answer 45

tend tor recieve much less afferent fibre information with one exception:

GTO –> terminate: laminae VII - IX (7-9)
primary muscle spindle receptors synapse directly on motor neurons

Question 46

laminae V (5) recieves

Answer 46

both small and large fibre inputs
respond to range of stimuli