Somatosensation 2 Shai.

Question 1

what are merkels disks

Answer 1

mechanoreceptors (pressure)

Question 2

what are pacinian corpuscles?

Answer 2

mechanoreceptors for pressure and vibration

Question 3

what are ruffini endings?

Answer 3

mechanoreceptors for light touch

Question 4

what are messiners corpuscles?

Answer 4

mechanoreceptors for light touch

Question 5

what are vertical tracts?

Answer 5

bundles of axons with the same origin and a common termination is a tract, column, leminiscus, or fascicle

Question 6

what is the white matter with regards to a vertical tract?

Answer 6

the ascending and descending tracts

Question 7

what is a funiculus?

Answer 7

big bundles of white matter

example of this is the dorsal funiculus

Question 8

what is the dorsal funiculus divided into?

Answer 8

two columns the right and the left

Question 9

what is the ascending tract do?

Answer 9

ascending carrys sensory information (synapse in the cord or goes straight to the brain

Question 10

what does the descending tract carry?

Answer 10

motor informaiton & synapses in the ventral horn or intermediate zone and then out to periphery

Question 11

What type of pathway for discriminitive touch and conscious prorpioception usse?

Answer 11

three neuron relay (poly synaptic)

Question 12

What are the levels of this three neuron relay for discriminitive touch and conscious proprioception?

Answer 12

primary conveys info from receptors to medulla

secondary convey info from medulla to thalamus

tertiary relays information from thalamus to cerebral cortex

Question 13

What do primary neurons include with regards to the dorsal column/medial leminiscus system?

Answer 13

many collateral branches entering the gray matter
-some collaterals that contribute to motor control, some influence activity in neurons in other sensory systems and others that influence autonomic regulation

Question 14

what do secondary neurons in the dorsal colum/medial leminiscus system include?

Answer 14

they are located in the nucleus gracilis or cutanetus.

they have axons that cross the midline as the internal acruate fibers, and then ascend to the thalamus.

Question 15

where is the nucleus gracilis located?

Answer 15

Lower extremities, so lower spinal cord

Question 16

where is the nucleus cuneatus ?

Answer 16

upper extremities and higher spinal cord???

Question 17

what do the tertiary neurons in the dorsal column/medial leminscus system include?

Answer 17

neurons that connect the thalamus to the sensory cortex.

those thaty have axons forming part of the thalamocorticial radiations which are fibers connecting the thalamus to the cerebral cortex

Question 18

What is the primary sensory cortex? and what does it do?

Answer 18

arease of the cortex that respond to somatosensory stim..

in the HUMUNCULUS

Question 19

Where are the somatosensory areas of the cerebral cortex?

Answer 19

primary sensory cortex- discriminiates among the size texture or shape of object.

somatosensory association areas analyse the information from the primary sensory area and the thalamus and provide stereognosis and memory of tactile and spatial environment.

Question 20

what does the thalamus do?

Answer 20

from my notes, it seems it helps with the MEMORY of an object

Question 21

What fibers detect temperature?

Answer 21

specialized free nerve endings of small myelinated and unmyelinated neurons

A-delta fibers->impulses produced by cooling (small myelinated)

C Fibers->information from heat (unmyelinated)

Question 22

what helps to find pain?

Answer 22

sensation and EMOTIONAL RESPONSE TO THE SENSATION

Question 23

what is nociceptive?

Answer 23

receptors or neurons that recieve or transmit information about stimuli that damage or threaten to damage tissue

Question 24

what is fast pain?

Answer 24

spinothalamic pain

initial and immediate sharp sensation that indicates the location of the injury

usually only 3 neuron path

Question 25

what is slow pain?

Answer 25

spinolimbic pain dull throbbing ache following fast pain not well localized (usually longer pain)

Question 26

Fast pain lateral pain system (tract?)

Answer 26

three Neuron system Primary- info into dorsal horn of spinal cord Secondary- axons of secondary cross midline and project from spinal cord to the thalamus Tertiary- project from the thalamus to the cerebral cortex

Question 27

what are other names for the fast pain lateral pain system?

Answer 27

spinothalamic pathway anterolateral system

Question 28

what is the difference between fast and slow pain?

Answer 28

fast pain-- info reaches somatosensory cortex so youre consciously aware of sharp pain if tissue damage occurs then you get slow pain resposnse. onset of slow pain is later than fast pain because impulses travel on smaller unmyelinated axons

Question 29

What is the medial pain system

Answer 29

divergent ascending network of neurons uses several pathways with variable numbers of projection neurons (not a 3 neuron pathway like fast pain)

Question 30

what does activity of the medial pain system cause?

Answer 30

affective, motivational, withdrawl, arousal and autonomic responses info is not somatotopically organized so you it cannot be precicely localized. achey pain, also if you get a scratch and dont see it bleeding, but then you look and then it hurts

Question 31

what are the neruons for the medial pain system?

Answer 31

1st neuron: small unmyelinated C fiber receptors are free nerve endings, sensitivie to noxious heat, chemical, or mechanical stimulation has a high threshold of c fibers ending that become sensiized with repeated stimulation

Question 32

what are ascending projection neurons?

Answer 32

axons of ascending projection neurons reach the midbrain reticular formation and limbic areas via three tracts in the atnerolateral spinal cord

Question 33

what are the three tracts in the anterolateral spinal cord?

Answer 33

spinomesencephalic spinoreticular spinolimbic

Question 34

of the three tracts of the anterolateral spinal cord, which one has informaiton that is perceived as pain?

Answer 34

spinolimbic

Question 35

what does the spinomesencephalic tract do?

Answer 35

carries nociceptive information to the superior colliculus and periaqueductal gray (part of the descending pain control system in the midbrain) is involved in turning eyes and head toward the source of noxious input and in activating descending tracts that control pain

Question 36

what does the spinoreticular tract do?

Answer 36

three ascending neurons synapse in the reticular formation reticular formation: a neural network in the brainstem that includes the reticular nuclei and their connection which modulates arousal, attention, and sleep waking cycles

Question 37

what does the spinolimbic tract do?

Answer 37

transmits slow pain information in the medial and interalaminar nuclei in the thalamus slow pain pathways privde info that produce automatic movements and autonomic and emotional responsess to noxious stimuli activity in the spinoreticular and spinolimbic result in arousal, withdrawl, autonomic and affective responses to pain.

Question 38

Temperature informaton-- how is it transmitted?

Answer 38

reticular formaiton nonspecific nuclei of the thalamus subcortical nuclei hypothalamus

Question 39

what happens to temperature information that does not reach conscious awareness?

Answer 39

contributes to arousal, gross localization and contributes to autonmic regulation

Question 40

what do unconscious relay tracts to the cerebellum do?

Answer 40

transmit information from proprioceptors and information about activity in spinal interneurons they relay information critical for adjusting movements inadequate proprioceptive input can cause ataxia bc loss of sensory feedback disrupts movement control

Question 41

what is the function of the spinocerebellar tracts?

Answer 41

info in the spinocerebrellar tracts come from the proprioceptrs spinal interneurons and descending motor pathways info that does not reach conscious awareness contributes to autonomic movements and postural adjustements

Question 42

if you have proproception vibration and fine touch in the body, what somatosensory pathway would it be?

Answer 42

dosal column- medial leminiscal

Question 43

if you have proproception vibration and fine touch in the face, what somatosensory pathway would thisbe?

Answer 43

trigeminal lemniscus

Question 44

if you have pain temprerature and crude touch, in the body what somatosensory pathway would it be?

Answer 44

``` anterolateral pathways - SPINOTHALAMIC (primary?) spinoreticular spinomesencephalic spinolimbic ```

Question 45

if you have pain temperature and crude touch to the face, what somatosensory pathway would it be?

Answer 45

trigeminothalamic tract

Question 46

what does the dorsal column medial leminiscus system include?

Answer 46

gracile fasciculus and cuneate fasciculus

Question 47

what does the dorsal column medial leminiscus system sensory include?

Answer 47

proprioception vibration and fine touch

Question 48

with the dorsal column medial leminiscus, what do the axons look like

Answer 48

large diameter,myelinated axons

Question 49

with the dorsal column medial leminiscus, what do the first order neurons do?

Answer 49

ascend in ipsilateral posterior columns through the gracile and cuneate fasiculus where they synapse

Question 50

with the dorsal column medial leminiscus, what do the second orderaxons do

Answer 50

second order neurons decussate as internal arcuate fibers in the nedulla then formal medial lemniscus , and then synapse in the thalamus at the VPL (ventral posterolateral nucleus)

Question 51

with the dorsal column medial leminiscus, what do the third orderaxons do?

Answer 51

project to primary somatosensory cortex

Question 52

with the trigeminal lemniscus, what happens

Answer 52

analogous to posterior column medial leminiscal pathway convey touch sensation for face to somatosensory cortex. this tract enters in the medulla and immediately decussates and then synapses in the thalamus at the VPM(ventral posteriormedial nucleus)

Question 53

what does the anterolateral ssytem include? and what type of sensation does it read?

Answer 53

lateral spinothalamic tract anterior spinothalamic tract pain and temperature, crude touch and pressure

Question 54

what does the spinothalamic tract look like?

Answer 54

small diameter unmyelinated axons

Question 55

what do the first order neurons in the spinothalmic tract do?

Answer 55

they synapse directly in the gray matter of the spinal cord (within 1-3 segments of entering the spinal cord)

Question 56

what do the second ordre neurons in the spinothalamic tract do?

Answer 56

cross in spinal cord anterior commissure ascend in the anterolateral whtie matter synapise in the thalamus at the ventral posterolateral neucleus

Question 57

what do the third order neurons in the spinothalmic tract do?

Answer 57

project to primary somatosensory cortex

Question 58

what does the trigeminothalamic tract do?

Answer 58

it follows the spinothalmic tract conveys pain temperature, crude touch sensaton from the face to the somatosensory cortex fibers enter at the medulla and immediately decussate synapse in the thalamus

Question 59

example of what the spinothalamic tract does, what would my response be?

Answer 59

"i detect something on my left foot" mediates discrimininative aspect of pain/temp aka the location and intensity

Question 60

example of what the spinoreticular tract does?

Answer 60

projects to VPL thalamus, then diffuse to cortex, conveys emotional/arousal aspect of pain OUCH!!

Question 61

what does the spinomesencephalic tract do ? an example.

Answer 61

projects to periaqueductal gray in midbrain, and participates in the central modulation of pain "ok thats better"