Sensory systems II

Question 1

what modalities are conveyed in the anterolateral system?

Answer 1

nociception and thermal sensation

Question 2

what percentage of nociceptive fibers transmit directly to the thalamus?

Answer 2

15%

Question 3

what percentage of nociceptive fibers transmit indirectly to the thalamus?

Answer 3

85%

Question 4

what type of pain sensation is transmitted by the neospinothalamic tract? does it reach consciousness?

Answer 4

fast, sharp, well-localized pain - yes

Question 5

which pathway is necessary for spatial and temporal discrimination of pain?

Answer 5

neospinothalamic

Question 6

what are the receptors for the neospinothalamic tract?

Answer 6

free nerve endings of Ad fibers

Question 7

where is the first order neuron cell body in the neospinothalamic tract?

Answer 7

DRG

Question 8

where is the second order neuron cell body in the neospinothalamic tract?

Answer 8

dorsal horn

Question 9

where do the axons from second order neospinothalamic tract cell bodies go?

Answer 9

cross in spinal cord and form spinothalamic tract

Question 10

where is the third order neuron cell body in the neospinothalamic tract?

Answer 10

VPL nucleus of thalamus

Question 11

where do the axons from first order neospinothalamic tract cell bodies go?

Answer 11

enter zone of Lissauer and then bifurcate to ascend or descend 1-3 levels to enter gray matter of dorsal horn (substantia gelatinosa)

Question 12

how is the lateral spinothalamic tract organized?

Answer 12

somatotopically - sacral most lateral, cervical most medial

Question 13

where do the axons from third order neospinothalamic tract cell bodies go?

Answer 13

axon traverses posterior limb of internal capsule and corona radiata to ascend to primary somatosensory cortex (Brodman’s area 3, 1, 2)