Somatosensory Pathways Ii

Front 1

What type of axons bring sensations of crude touch, temperature, and pain into the spinal cord?

Back 1

small diameter fibers that are lightly myelinated that are A-delta and C-fibers

Front 2

Nociception is ___________

Back 2

neural processes of encoding and processing noxious stimuli

Front 3

The primary neurona cell body of the ALS system is found in the ________.

Back 3

Dorsal root ganglia

Front 4

Which fibers of the ALS carry sharp first pain?

Back 4

A-delta

Front 5

The ____ fibers carry dull and aching second pain.

Back 5

C

Front 6

The axons of the ALS enter, forming the dorsal roots, the ______ region of ________

Back 6

lateral region of the DREZ

Front 7

As the axons of the ALS enter the spinal cord what occurs?

Back 7

The axons will either descend or ascend 1 to 2 spinal segments and may bifurcate in Lissauer's tract before entering the gray matter of the dorsal horn

Front 8

After the axons of the ALS enter the dorsal horn where will they synapse onto second order neurons?

Back 8

The axons will synapse on second order neurons in the marginal zone, substantia gelatinosa, and nucleus proprius

Front 9

Lamina ___ : marginal zone

Back 9

I

Front 10

Lamina ___: substantia gelatinosa

Back 10

II

Front 11

Lamina ____ : Nucleus proprius

Back 11

III-IV

Front 12

Where do the second order neurons send axons to decussate in the ALS?

Back 12

second order neurons send axons to decussate at the level in the anterior white commisure

Front 13

When will the second order neurons ascend in the ALS? where do they travel to?

Back 13

after decussation in the anterior white commisure the axons will ascend in the lateral funiculus/colmn as the ALS

Front 14

What are the 3 parts of the anterolateral system?

Back 14

1. spinothalamic
2. spinoreticular
3. spinomesencepanphalic

Front 15

Which part of the ALS synapses in the VPL of the thalamus and conveys discriminative aspects of pain and temperature such as location and intensity

Back 15

spinothalamic

Front 16

_________ synapse sin the reticular formation of the medulla and pons and is important in the arousal aspect of pain.

Back 16

reticulospinal

Front 17

This part of the ALS system synapses in the midbrain and is important for orienting to salient stimuli and descending pain modulation.

Back 17

Spinomesencephalic tract

Front 18

What two porjection does the spinoreticular tract synapse on in the medualla and pons?

Back 18

1. intralaminar thalamic nuclei
2. mediodorsal nuclei of the thalamus

Front 19

As the spinoreticular tract synapses on nuclei in the thalamus what is its function?

Back 19

These nuclei have widespread projections to the cortex and are involved in mediating the emotional and arousal aspects of pain

Front 20

What part of the midbrain does the spinomesencephalic tract synapse in?

Back 20

superior colliculus

Front 21

The superior colliculus is important in what function with respect to the spinomesencephalic tract?

Back 21

this is the brain region important in orienting to relevant stimuli

Front 22

What part of the midbrain is synapsed on by the spinomesencephalic tract that is responsible for modulation of descending pain?

Back 22

Periaqueductal gray (PAG) is important in descending pain modulation

Front 23

What nuclei does the PAG project to in the medulla?

Back 23

PAG projects to the serotonergic raphe nuclei in the medulla which project to the dorsal horn of the spinal cord to suppress pain transmission

Front 24

How is pain transmission suppresed by the PAG?

Back 24

1. Directly by inhibiting dorsal horn projection neurons that transmit pain to the cortex
2. Exciting inhibitory interneurons in dorsal horn that inhibit ascending neurons that transmit pain to the cortex

Front 25

What part of the ALS system might be a survival mechanism that allows individuals to continue function despite sudden pain?

Back 25

Spinomesencephalic tract
--PAG

Front 26

Where are the third order neurons located in the spinothalamic tract part of the ALS?

Back 26

The spinothalamic tract synapses on third order neurons in the VPL of the thalamus

Front 27

What vascular zone is the ALS in as it enters the brainstem?

Back 27

lateral vascular zone as it ascends through the brainstem

Front 28

What other nucleus does the ALS second order axons synapse on in the thalamus?

Back 28

Synapses on the mediodorsal nucleus of thalamus
-- this projects the the anterior cingulate gyrus of the limbic system

Front 29

The third order neurons project the the primary somatosensory cortex through the _______ as somatosensory radiations.

Back 29

medial portion of PLIC

Front 30

VPL also projects to the anterior cingulate gyrus and the insular cortex. What system are these part of?

Back 30

Limbic System which is involved in coding emotional/affective responses to pain

Front 31

What contais the 4th order neurons of the ALS system?

Back 31

primary somatosensory cortex
BA 3,1,2

Front 32

In what part of the primary somatosensory cortex do the afferent axons terminate?

Back 32

BA 3b, 1

Front 33

What areas of the cortex does the ALS 4th order neurons project to?

Back 33

1. posterior parietal cortex (BA 5,7)
2. Secondary somatosensory cortex of the parietal operculum
3. interconnections with the primary motor cortex (BA4)

Front 34

What is contained within the posterior parietal cortex?

Back 34

unimodal association cortex for higher order pain processing

Front 35

What is contained within the secondary somatosensory cortex of the parietal operculum?

Back 35

hetermodal association cortex for higher order sensory processing

Front 36

Describe the Gait Control Theory of Pain

Back 36

sensory input from A-beta fibers (Large diameter PCML) reduce pain transmission in dorsal horn
-- neural circuitry explaining why rubbing your shin after you've hit it makes it feel better

Front 37

What theory of pain modulation is described as input from the spinomesencephalic tract, input hypothalamus, amygdala, and cortex, projects to serotinergic raphe nuclei in the rostral ventral medulla which projects to dorsal horn: this gives direct inhibition of secondary neurons of spinothalamic tract in dorsal horn and indirect inhibition by exciting the inhibitory dorsal horn interneurons that then inhibit the secondary neurons of the spinothalamic tract

Back 37

PAG (periaqueductal gray)

Front 38

How do opiates help to modulate pain?

Back 38

Opiate receptors and endogenous opiods are concentrated in PAG, RVM, and dorsal horn of the SC

Front 39

What artery supplies the ALS in the spinal cord?

Back 39

anterior spinal artery
-arises from vertebral artery

Front 40

If there were a lesion of the anterior spinal artery what somatosensory tracts would it affect?

Back 40

ALS
-bilateral loss of pain & temperature sensation in the dermatomes below the level of the lesion

Front 41

If there were an infarct to the posterior spinal artery would it affect the ALS system?

Back 41

Yes
Posterior spinal artery supplies Lissauer's tract
--ipsilateral loss of pain & temperature in a small region innervated by the primary afferents affected by the lesion

Front 42

What vascular zone does the ALS travel in through the medulla?

Back 42

lateral vascular zone which is supplied by PICA and the vertebral artery

Front 43

_______ and _________ are the blood supply to the part of the medulla that the ALS runs through.

Back 43

vertebral artery and PICA

Front 44

If there were a lesion of the vertebral artery and PICA in the medulla they would affect the _______ somatosensory system

Back 44

ALS
-contralateral loss of pain and temperature sensation to 1/2 of the body

Front 45

What vascular zone would you find the ALS traveling through in the pons?

Back 45

lateral vascular zone
Circumferential branches of basilar artery

Front 46

What arteries supply the ALS in the pons?

Back 46

circumferential branches of the basilar artery in the lateral vascular zone

Front 47

If there were a lesion of the circumferential arteries of the basilar artery what symptoms would be shown with respect to the ALS system?

Back 47

contralateral loss of pain and temperature in 1/2 of the body

Front 48

What artery supplies the midbrain in the lateral vascular zone?

Back 48

PCA

Front 49

Where is the ALS system found in the midbrain? What artery supplies this?

Back 49

lateral vascular zone
PCA

Front 50

In what part of the brainstem do the ALS and PCML system enter the same vascular zone? What are the arteries responsible for this zone?

Back 50

From the midbrain on the ALS and PCML are in the same vascular zone.
The PCA is responsible for supplying this part of the midbrain with blood

Front 51

If there is a lesion of the PCA in the midbrain how is it going to affect the ALS system?

Back 51

contralateral loss of pain & temperature sensation 1/2 of the body

Front 52

________ & __________ arteries supply the VPL of the thalamus, which contains neurons for the ALS system.

Back 52

Thalamogeniculate and thalamoperforator arteries which are small branches of PCA

Front 53

A lesion occurs in the thalamogeniculate/thalamoperforateor arteries, how does it affect the thalamus with respect to the ALS?

Back 53

A lesion of these vessels would produce contralateral loss of pain & temperature in 1/2 of the body

Front 54

What vessels are susceptible to lacunar infarcts? What will the result be if this happens?

Back 54

Thalamogeniculate & Thalamoperforator arteries that supply the VPL of the thalamus
-an infarct would produce a pure sensory stroke

Front 55

________ _________ artery is a small branch of the internal carotid artery that supplies PLIC

Back 55

anterior choridal artery

Front 56

Where does the ALS system travel through the internal capsule?

Back 56

posterior limb of the internal capsule

Front 57

If the anterior choridal artery suffers an infarct what would be the resulting sensory loss with respect to the ALS?

Back 57

contralateral loss of pain and temperature sensation to 1/2 of the body

Front 58

If there is an infarct of the ACA, what would be the resulting sensory loss with respect to the ALS?

Back 58

loss of pain and temperature sensation from contralateral leg

Front 59

What type of lesion in the cortex would produce loss of pain and temperature sensation from the contralateral arm?

Back 59

MCA infarct

Front 60

define stereogenosis.

Back 60

ability to perceive the form of an object by using the sense of touch

Front 61

define graphesthesia

Back 61

tactile ability to recognize writing on the skin

Front 62

define aphasia

Back 62

impairment of language modality

Front 63

_______ is weakness on one side of the body

Back 63

hemiparesis

Front 64

_______ is defective vision/blindness in half of the vision field of one or both eyes

Back 64

hemianopia

Front 65

What type of lesion would produce:
-bilateral loss of all sensation in dermatomes below the level of the lesion
-all motor loss below the level of the lesion

Back 65

Transverse cord lesion
-this could be caused by trauma, tumors, MS

Front 66

A hemicord lesion would produce what type of signs?

Back 66

-Ipsilateral loss of fine touch & proprioception in dermatomes below lesion (PCML before decussation)
-Contralateral loss of pain & temperature in dermatomes below the lesion (ALS after decussation)
-Small ipsilateral loss of pain & temperature above site of lesion due to disruption of descending primary afferents in Lissauer's tract
-Ipsilateral motor loss (corticospinal after decussation/LMN signs)

Front 67

What could cause a hemicord lesion of the spinal cord?

Back 67

trauma, compression by tumors, MS

Front 68

Syringomyelia, intrinsic spinal cord tumors and spinal cord contusion could all be causes of what type of lesion?

Back 68

Central cord syndrome (small lesion)

Front 69

Bilateral loss of pain & temperature sensation in dermatomes associated with injured spinal level; due to disruption of secondary afferents in the anterior white commisure is due to what type of lesion.

Back 69

Central cord syndrome (small lesion)
a cervical cord lesion can produce a cape distribution of sensory loss

Front 70

What types of symptoms would point towards a diagnosis of posterior cord syndrome?

Back 70

-Bilateral loss of fine touch & proprioception in dermatomes below the level of the lesion (PCML)
-no motor loss
-no loss of pain & temperature

Front 71

What are some possible causes of posterior cord syndrome?

Back 71

trauma, compression by tumors, MS, pernicous anemia, tabes dorsalis

Front 72

Bilateral loss of pain & temperature in dermatomes below the level of a lesion and bilateral loss of motor control with LMN signs are characteristics of what type of lesion of the spinal cord?

Back 72

Anterior cord syndrome
this could be caused by trauma, MS, or an anterior spinal artery infarct

Front 73

Where is the decussation of the PCML system located?

Back 73

internal arcuate fibers of the pyramids of the medial lemniscus in the medulla

Front 74

Where is the decussation of the ALS system located?

Back 74

ALS decussation is in the anterior white commisure of the spinal cord

Front 75

Where is the decussation of the corticospinal tract located?

Back 75

Corticospinal decussation is located in the pyramidal decussation of the medulla at the cervicomedullary junction.