Ascending and Descending tracts Flashcards

1
Q

What modality are ascending tracts

A

Sensory

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2
Q

What modality are descending tracts

A

Motor

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3
Q

What is the DCML

A

Dorsal Column Medial Lemniscus tract

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4
Q

What sensation does the DCML detect

A

fine touch

conscious proprioception

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5
Q

Where do fibres in the DCML tract cross over to the contralateral side

A

2nd order nerves cross over at the level of the medulla

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6
Q

What is the dorsal column in the spinal cord made up of

A

fasiculus gracilis

fasiculus cuneatus

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7
Q

From where does the nucleus gracilis carry information

A

Legs

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8
Q

From where does the nucleus cuneatus carry information

A

arms

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9
Q

What is the STT

A

Spinothalamic tract

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10
Q

What sensation does the STT detect

A

pain
temperature
crude touch / deep pressure

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11
Q

Where do fibres in the STT cross over to the contralateral side

A

2nd order neurons cross over segmentally at the level they enter the spinal cord

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12
Q

What action does the corticospinal tract help control

A

fine motor movement

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13
Q

What is the corticospinal tract also known as (CST)

A

pyramidal tract

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14
Q

what kinds of corticospinal tracts are there

A

lateral and ventral

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15
Q

_% fibres cross over __ in the lateral CST

A

85% fibres cross over the midline at the decussation of the pyramids in the medulla

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16
Q

where do fibres in the ventral CST cross over

A

segmentally in the spinal cord as they need to leave

17
Q

What is the internal capsule

A

deep subcortical tissue of white matter, all modalities run through this

18
Q

Give examples of extra-pyramidal tracts

A

tectospinal - input to H+N region
reticulospinal - reticular formation at core of brainstem (pons and medulla): consciousness, breathing, cariac
vesticulospinal - input to anti-gravity muscles

19
Q

What is Brown Séquard syndrome

A

hemisection of the spinal cord resulting in:
ipsilateral loss of fine touch, proprioception and fine movement (DCML + CST)
contralateral loss of pain and temperature (STT)

20
Q

Where is the primary somatosensory cortex found

A

post central gyrus

21
Q

Where is the primary somatomotor cortex found

A

pre central gyrus

22
Q

How many neurons are involved in ascending tracts

A

3

1st, 2nd and 3rd order neurons

23
Q

How many neurons are involved in descending tracts

A

2

UMN + LMN

24
Q

Where do 3rd order neurons in ascending tracts synapse

A

thalamus in the brain

25
Q

path of the corticobulbar tract

A

passes through internal capsule to reach the brainstem

26
Q

fibres in the corticobulbar tract innervate CN nuclei bilaterally except __

A

CN VII
UMN of facial nerve has contralateral innervation of muscles of the lower face and bilateral innervation of muscles of the upper face
ie R brain controls left lower facial muscles
CN XII
UMN of hypoglossal has contralateral innervation to the tongue

27
Q

central lesion of CN VII causes forehead sparing/involvement

and give an example of this

A

sparing
because upper facial muscles have bilateral innervation
stroke

28
Q

peripheral lesion of CN VII causes forehead sparing/involvement
and give an example of this

A

involvement

Bell’s palsy

29
Q

what is the rubrospinal tract

A

originates in the red nucleus of the midbrain
excites upper limb flexors
inhibits upper limb extensors

30
Q

the rubrospinal tract innervates both upper and lower limbs, true or false

A

FALSE

only innervates upper limbs

31
Q

what is the reticulospinal tract

A

originates in pons/medulla

excites upper and lower limb extensors

32
Q

in terms of descending tracts, what is the order of dominance over the body

A
  1. corticospinal tract
  2. rubrospinal tract
  3. reticulospinal tract
33
Q

what happens if the CST is lost

A

rubrospinal tract is next dominant

therefore upper limb flexion ie decorticate posturing

34
Q

what happens is the rubrospinal tract is lost

A

reticulospinal tract is next dominant

therefore there is both upper and lower limb extension ie decerebrate posturing

35
Q

fasciculus gracilis is from below/above T6

A

below