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Med School Yr 2 > 2 - Ascending & Descending Pathways > Flashcards

2 - Ascending & Descending Pathways Flashcards

1
Q

how many neurones do ascending pathways have?

A

3
* primary - same side as sensatin
* secondary - decussates
* tertiary - within the brain

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2
Q

what 3 ascending tracts are responsible for conscious sensation/

A

spinothalamic
spinal reticular
dorsal column

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3
Q

what is the role of the spinothalamic tract?

A

anterior - crude touch and pressure
lateral - pain and temperature sensation

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4
Q

describe the route of each neuron in the spinothalamic tract:

A

first order - peripheral receptors to dorsal horn
secondary - decussates to other side of spinal cord and travels to thalamus
thrid order - thalamus to somatosensory cortex through internal capsule

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5
Q

what is the role of the spinalreticular tract?

A

automatic response to pain

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6
Q

what is the role of the dorsal column pathway?

A

fien tough, two touch discrimination, vibration, proprioception

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7
Q

where does the spinothalamic tract decussate?

A

spinal cord

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8
Q

where does the dorsal column pathway synsapse?

A

medulla

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9
Q

describe the routes of the neurones in the dorsal column:

A
  • first order - travel through fasciculus cuneatus or fasciculus gracilis
  • second order - synapses in medulla and travels to thalamus via medial lemniscus
  • third order - to somatosensory cortex
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10
Q

what is the role of the fasciculus cuneatus?

A

carries upper limb info (T6 and above)

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11
Q

what is the role of the fasciculus gracilis?

A

carries infor from the lower limb (below T6)

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12
Q

what ascending pathways are responsible for unconscious perception?

A

dorsal spinocerebellar
anterior spinocerebellar
cuneocerebellar

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13
Q

what is the role of the dorsal spinocerebellar tract?

A

transmits proprioceptive info from lower limbs to cerebellum

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14
Q

what is the role of the ventral spinocerebellar tract?

A

transmits proprioceptive info from lower limbs to cerebellum

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15
Q

what is the role of the cuneocerebellar tract?

A

transmits proprioceptive info from upper limb and neck

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16
Q

describe the route of the neurones in the dorsal spinocerebellar tract

A
  • 1st synapses onto second in dorsal horn
  • second travels to cerebellum
  • completely ipsilateral
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17
Q

describe the route of the neurones in the ventral spinocerebellar tract

A
  • ipsilateral but decussates twice
  • decussates on entry to spinal cord and in white matter of cerebellum
18
Q

lesions in the spinothalmic tract result in what?

A

loss of contralateral:
* crude touch
* pressure
* pain
* temp

19
Q

lesions in the dorsal column pathway result in what?

A

loss of ipsilateral:
* proprioception
* vibration
* fine touch

20
Q

spinocerebellar lesions lead to what?

A

loss of ipsilateral coordination

21
Q

what are the two pyramidal descending pathways?

A
  • corticospinal tract
  • corticobulbar tract
22
Q

what is the corticospinal tract responsible for?

A

muscle control of the body

23
Q

describe the route of neurones in the corticospinal tract:

A
  1. cell bodies in cerebral cortex
  2. pass through internal capsule
  3. pass through crus cerebri
  4. pass through pons
  5. at pyramids of medulla 75% fibres decussate (lateral) and synapse with LMN in ventral horn
  6. 25% do not decussate (anterior) - later decussate at cervical and thoracic levels
24
Q

where does the corticospinal tract decussate?

A

75% - pyramids of medulla
25% - cervical and thoracic levels

25
Q

what is the role of teh corticobulbar tract?

A

voluntary control of face, head and neck

26
Q

what is the route of the neurones in the corticobulbar tract?

A
  • originate in cerebral cortex
  • pass through intenral capsule
  • do not descend into spinal cord but synapse onto cranial nerve nuclei
27
Q

the neurones of the corticobulbar tract innervate how?

A

bilaterally
* provide motor sensation to both sides of face

28
Q

what are the 4 extrapyrimidal descending tracts?

A
  1. rubrospinal tract
  2. reticulospinal tract
  3. vestibulospinal tract
  4. tectospinal tract
29
Q

what is the role of the rubrospinal tract?

A

motor control

30
Q

where does the rubrospinal tract originate?

A

red nucleus

31
Q

what is the role of the reticulospinal tract?

A
  • medial - facilitates contraction and increases tone
  • lateral - inhibits contraction
32
Q

where does the reticulospinal tract originate?

A

medial - pons
lateral - medulla

33
Q

where does the vestibulospinal tract originate?

A

vstibular nuclei

34
Q

what is the role of the vestibulospinal tract?

A

balance and posture

35
Q

where does the tectospinal tract originate?

A

superior colliculus

36
Q

what is the role of the tectospinal tract?

A

head and eye coordination

37
Q

what are signs of extrapyrimidal tract injuries?

A
  • parkinsonisms
  • chorea
  • athetosis
  • dystonia
38
Q

how many cranial nerve nuclei are motor?

A

10

39
Q

how many cranial nerve nuclei are sensory?

A

8

40
Q

Label the cranial nerve nuclei

A

Med School Yr 2 (96 decks)

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