lecture 20

Question 1

describe the difference btwn muscle spindle and muscle tendon location

Answer 1

muscle spindles located within muscles, muscle tendons located within skeletal muscle tendons

Question 2

describe the difference btwn muscle spindle and muscle tendon detection

Answer 2

spindles detect change in length of muscles, while tendon detects changes in tension of the muscle

Question 3

review - where is the substantia gelatinosa?

Answer 3

posterior dorsal horn of sc

Question 4

review - where is the nucleus proprius?

Answer 4

posterior dorsal horn of sc, anterior to sub gel

Question 5

review - where is the dorsal nucleus (Clarke’s Column)?

Answer 5

almost in bridge btwn two sides of sc gray matter but just lateral

Question 6

list the relevant ascending pathways of the sc

Answer 6

• dorsal column system (cuneate fasciculus, gracile fasciculus)
• dorsal lateral fasciculus (Lissaurer’s tract)
• dorsal posterior spinocerebellar tract
• ventral spinocerebellar tract

Question 7

list the relevant descending pathways of the sc

Answer 7

• lateral motor systems (lateral corticospinal tract, rubrospinal tract)
• medial motor systems (reticulospinal tract, vestibulospinal tract and tectospinal tract)
• anterior corticospinal tract

Question 8

where do the mechanosensory pathways terminate in the sc?

Answer 8

posterior (dorsal) columns

Question 9

where do the mechanosensory pathways cross over?

Answer 9

level of caudal medulla (after nucleus cuneatus)

Question 10

there are 4 mechanosensory pathways, where do they go?

Answer 10

3 to cerebrum

1 to cerebellum

Question 11

what is the convoluted mechanosensory pathway from the body to the cerebellum for?
why does this make sense?

Answer 11

• unconcious proprioception

- makes sense bc cerebellum is involved in coordinating precise movements and muscle tone

Question 12

describe the pathway for mechanosensation from the head to the cortex

Answer 12

• pain, temp, touch, pressure (teeth), etc
• trigeminal nuclei –> trigeminal spinal nucleus –> trigeminal nucleus (mesencephalic and main sensory) –> trigeminal lemnciscus –> ventral posterior medial nucleus of thalamus –> primary somatic sensory cortex

Question 13

trigeminal main sensory nucleus connected to?

Answer 13

trigeminal motor nucleus (important for descending pathways)

Question 14

how is the primary somatosensory cortex organized?

Answer 14

somatotopicly

Question 15

where does the somatosensory association cortex (posterior parietal) receive its input from?

Answer 15

primary and secondary somatic sensory cortices

Question 16

from the posterior parietal cortex, where is information passed?

Answer 16

to the inferior parietal cortex

Question 17

what would be the result of damage to the right side of the inferior parietal gyrus?

Answer 17

left spacial neglect

Question 18

what would be the result of damage to the right side of the temporal-parietal junction?

Answer 18

left spacial neglact

Question 19

why doesn’t damage to the inferior parietal gyrus or the temporal-parietal junction cause visual deficits?

Answer 19

patients ignore the left side of their body as well as the space it occupies

Question 20

what would be the result of stimulating the right side of the angular gyrus? explain.

Answer 20

out-of-body experience
(right angular gyrus integrates visual information - sight of your body and the information that creates the minds representation of the body, thus, representation in our brain can be dissociated from our real body)

Question 21

describe left side neglect

Answer 21

• the left parietal cortex only oversees attention to the right side of the bosy and the space it occupies
• the right parietal cortex mediates attention to both sides
• lesion to the right parietal cortex gives rise to contralateral neglect because the left side has lost its only surveillance

Question 22

what would be the result of stimulating the left side of the angular gyrus?

Answer 22

sensation of a shadowy person lurking right behind them

Question 23

where do the pain/temperature pathways terminate in the sc?

Answer 23

dorsal horn –> spinothalamic tract (anterolateral system)

Question 24

what are the main tracts in the anterolateral pathway?

Answer 24

• spinothalamic
• spinoreticular
• spinomesencephalic

Question 25

what is the associated function of the spinothalamic tract?

Answer 25

discriminative - how and where - aspects of pain and temp

Question 26

what is the associated function of the spinoreticular tract?

Answer 26

emotional and arousal aspects of pain

Question 27

what is the associated function of the spinomesencephalic tract?

Answer 27

modulation of pain

Question 28

there are 2 pain/temperatire sensation pathways, where do they cross over?

Answer 28

L4, C8