11 Somatosensory System

Question 1

DC-ML: fx

Answer 1

conveys vibration, joint position, well localized touch

Question 2

relay sites: DC-ML

Answer 2

1. caudal medulla, dorsal column nuclei (cuneate and gracile)
2. thalamus, ventral posterolateral nucleus

Question 3

decussation: DC-ML

Answer 3

caudal medulla

Question 4

first neuron: DC-ML

Answer 4

sensory neuron
cell body: DRG (dorsal root ganglion)
Process: dorsal column-> internal arcuate fibers (DECUSSATE)

Question 5

second neuron: DC-ML

Answer 5

medial lemniscus to VPL

Question 6

third neuron: DC-ML

Answer 6

VPL

Question 7

fasciulus cuneatus: Upper Ex.

Answer 7

touch, pressure, vibration, join position

Question 8

Fasiculus Gracilis: Lower ex

Answer 8

touch, pressure, vibration, join position

Question 9

lesion: spinal dorsal columns

Answer 9

ipsilateral
loss of vibration, joint sense, well localized touch
test: 2 point touch

Question 10

lesion: medial lemniscus

Answer 10

contra-lateral side
loss of vibraiton, joint sense, well localized touch
test: 2-point touch

Question 11

lesion: VPL

Answer 11

contralateral loss of
vibraiton, joint sense, well localized touch
test: 2-point touch

Question 12

Fx: spinothalamic tract

Answer 12

pain, temperature, light touch

Question 13

1st: spinothalamic tract

Answer 13

small diameter, sensory fiber

terminate in substantia gelatinosa

Question 14

substantia gelatinosa

Answer 14

dorsal horn site of control of pain from spinothalamic trac

Question 15

2nd: spinothalamic tract

Answer 15

cell bodies: ipsilateral dorsal horn
decussate: white commissure of spinal chord
proceed up he ventrolateral funiculus

Question 16

3rd: spinothalamic tract

Answer 16

cell bodies: VPL

processes to somatosensory cortex

Question 17

collaterals; spinothalamic tract

Answer 17

reticular formation, peraqueductal gray

Question 18

periaqueductal gray

Answer 18

suppresses pain

Question 19

lesion: ventral white commissure

Answer 19

loss of pain, temperature, light touch at level of damage

Question 20

lesion: ventral white commissure, spinothalamic tract

Answer 20

diminishes pain at the level of damage

Question 21

fx: CN V

Answer 21

sensory to face, motor muscles of mastication

Question 22

1st: CN V

Answer 22

sensory neurons, both pacinian corpuscles vibrations and merkel cells for light touch

Question 23

Gasserian Ganglion

Answer 23

a sensory ganglion of the trigeminal nerve tucked in the cavernous sinus

Question 24

CN V: large diameter

Answer 24

well localized touch (pin), pressure, vibration

Question 25

CN V: smal diameter fibers

Answer 25

pain, temperature, and light touch (brush)

Question 26

chief sensory nucleus of CN V

Answer 26

function: all the sensory branches of the trigeminal terminate here
located: adjacted to the middle cerebellar peduncle in the dorsolateral pons

decussate to the ventrolatleral trigeminothalamic tract

Question 27

fx: ventral trigeminothalamic tract

Answer 27

proprioception, fine touch (pin), vibration

pons-> principal trigeminal nucleus-> decussate.> Ventral, Posterior, Medial Nucleus

Question 28

dorsal trigeminal-thalamic tract

Answer 28

pain, temperature, light touch (brush)

pons.> medulla. spinal trigeminal tract.> spinal trigeminal complex-> decussation-> Ventroposteriolateral nucleus

Question 29

what are the two tracts that make face sensation bilateral

Answer 29

ventral trigeminothalamic tract

dorsal trigeminal tract

Question 30

lesion: lateral brain stem

Answer 30

damage to spinal tract and nucleus of trigeminal

causes ipsilateral loss of pain and temperature

tested with corneal reflex

Question 31

Brown-Sequard syndrome

Answer 31

board question