Lecture 13 - Corticospinal tract and other Flashcards

1
Q

What are the three main long tracts of the nervous system?

A
  1. Lateral cortico-spinal tract —-MOTOR
  2. Posterior Columns —- sensory (vibration, joint position and fine touch)
  3. Anterolateral pathways —- sensory (pain, temperature, crude touch)
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2
Q

Where is primary somatosensory area?

A

Brodmann’s area 3, 1 and 2

post central gyrus

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3
Q

Where is the primary motor area?

A

Brodmann’s area 4

precentral gyrus

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4
Q

How does the presentation of a lesion in a primary motor or sensory cortex differ from a lesion in an association cortex of sensory and motor.

A

Lesion in primary cortex - deficits in basic movement and sensation

Lesion in association cortex - deficits in higher order sensory analysis or motor planning

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5
Q

Describe the lateral corticospinal tract (the pathway)

A

over half of fibres originate in PRIMARY MOTOR CORTEX, others from the premotor and supplementary motor, or parietal.

  • includes GIANT BETZ cells, which are the largest neurons all the way from cortex to brainstem.
  • cerebral cortex > corona radiata > internal capsule, where white matter pathways converge and funnel, condensing down to fewer and fewer fibers, as connections to different subcortical structures are made
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6
Q

What is the corona radiata

A

the upper portions of the cerebral white matter

the corticospinal tract goes through this

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7
Q

What does the internal capsule look like

A

there is a right and left one
theyre little ‘v’ shape arrowheads pointing inwards, towads each other.

thalamus sits between then
and putamen on the other sides of them

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8
Q

What are the different parts of the internal capsule

A

Left and right internal capsules each have an anterior limb, genu, and posterior limb.

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9
Q

What does the anterior limb of the internal capsule seperate

A

It seperates the head of caudate (which sits inwards) from the putamen and globus pallidus

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10
Q

What does the posterior limb of the internal capsule seperate

A

It seperates the putamen and globus palladus (outwards) from the thalamus.

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11
Q

Where does the corticopsinal tract lie in the internal capsule

A

in the posterior limb

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12
Q

Where does the corticospinal tract go on the spinal cord

A

Anterior limb

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13
Q

Describe the feedback systems

A

basal ganglia and cerebellum feedback to the cerebral cortex through the thalamus, which go to brainstem and then the lateral and medial motor systems.

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14
Q

What NT do the lateral corticospinal tracts use

A

Ach

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15
Q

What can some antipsychotics do?

A

Older antipsychotics, such as Chlorpromazine, can give a movement disorder due to excess dopamine, causing hyperactivation of the circuits.

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16
Q

Where does the lateral corticospinal tract cross over

A

pyramidal decussation

85% of the neurons - the remaining become the anterior corticospinal tract

17
Q

From the posterior, genu to anterior limb of the intenral capsule, describe what areas of the body are represented on it.

A

L(i)TAF

leg trunk arm face

18
Q

What are corticobulbar fibers

A

these are fibers that go from cortex to brainstem

eg. motor fibers for the face

because they dont go to the spine, so not corticospinal

19
Q

What does a lesion in the internal capsule usually produce?

A

despite the somatotopic arrangement, lesions usually produce weakness in ENTIRE CONTRALATERAL BODY, because of how compact it is.

however, can sometimes create more selective motor deficits.

20
Q

Where is the somatotopic arrangement in the midbrain

A

the middle one-third of the basis pendunculi, on the cerebral peduncles.

goes LTAF, from outside towards middle.

this is on each side/hemisphere.

21
Q

What are the two lateral motor pathways

A
  • lateral corticospinal tract

- rubrospinal tract

22
Q

What tract is made up of the 15% of fibres that do not cross over at the pyramidal decussation

A

anterior contricospinal tract

  • controls bilateral axial and girdle muscles.