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My Packs: (UWO) (KIN 1080) > Lecture 13 > Flashcards

Lecture 13 Flashcards

1
Q

Explain:

Beating Heart Illusion

A
  • Cortical magnification reduced in V1 for peripheral vision
  • Peripheral vision has low spatial awareness
  • Brain updates the contours of the blurry heart constantly, makes heart appear larger and smaller
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2
Q

Describe:

Ventral-visual pathway

A
  • Projects to the temporal lobe
  • A visual pathway that can be tricked
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3
Q

What is the relationship between auditory cues and reaction times?

A

The louder the tone, the faster the reaction time

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4
Q

What does the reaction of clenching the teeth show?

A

Motor plans can come from subcortical structures

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5
Q

What is unique about subcortical responses?

A

Results from being startled, and below conscious threshold, meaning you cannot control it

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6
Q

What are the two components of the pyramidal tracts?

A
  1. Corticobulbar tract
  2. Corticospinal tract
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7
Q

Describe:

Upper motor neuron

A
  • Cell body must be in cortex, and axon projects to spinal cord
  • Contains over a million in the pyramidal tract
  • Contains over a million axons of which most are myelinated - thus is fast
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8
Q

What does myelin support?

A

Speed of neural conduction

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9
Q

Where do the pyramidal tracts originate and what do they innervate?

A
  • Originate in M1, SMA, PMA, parietal cortex, and some other cortical areas
  • Primarily goes on to innervate alpha motor neurons, controlling muscles
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10
Q

What motor actions does the pyramidal tracts control?

A

Facial, axial (back and stomach, involved in posture), and intrinsic musculature (muscles of the hand and feet associated with fine digit control)

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11
Q

What allows for fast conduction of upper motor neurons? How fast?

A
  • Size of the axons (diameter, length etc.)
  • Myelination
  • 100 m/s
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12
Q

What are the corticospinal tracts split into?

A

Ventral and lateral corticospinal tracts

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13
Q

Describe:

Corticobulbar tract

A

Contains upper motor nuerons that project in a region of the brain stem known as the “bulb”

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14
Q

What do upper motor neurons of the corticobulbar tract innervate?

A

Lower motor neurons that control facial muscles

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15
Q

What are lower motor neurons also known as?

A

Alpha motor neurons

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16
Q

Where does the corticobulbar tract extend from and to?

A
  • Extends from M1
  • Goes to the ‘bulb’
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17
Q

What is the ‘bulb’?

A

Brain stem

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18
Q

What does the corticobulbar tract control?

A

Facial muscles and muscles of mastication (chewing)

19
Q

What are the 2 components of the corticobulbar tract?

A
  1. Rostral components
  2. Caudal components
20
Q

What do the rostral and caudal components of the corticobulbar tract innervate?

A
  • Rostral component innervates upper facial musculature
  • Caudal component innervates lower facial musculature
21
Q

True or False:

Rostral component innervates bilaterally

A

True

22
Q

What does innervating bilaterally mean? What is the opposite of innervating bilaterally?

A

Bilaterally: Goes to both sides of the face
Opposite is contralateral - only goes to one side of the face

23
Q

True or False:

The caudal component innervates bilaterally

A

False, the caudal component innervates contralerally

24
Q

In corticobulbar tract injuries:

Give an example of an lower motor neuron injury and an upper motor neuron

A
  • Lower motor neuron: Bell’s Palsy
  • Upper motor neuron: Stroke
25
Q

Describe:

Bell’s Palsy

A
  • Causes paralysis of the entire side of the brain
  • Issue at level of lower motor neuron
  • Impairs projection to upper and lower facial muscles
26
Q

Describe (in terms of upper motor neuron injury):

Stroke

A
  • The forehead is not paralyzed
  • As only the lower facial muscles is affected, the upper facial muscles are not paralysed
27
Q

Define:

Pyramidal decussation

A

The crossing of the fibers of the corticospinal tracts from one side of the central nervous system to the other near the junction of the medulla and the spinal cord

28
Q

When does the ventral corticospinal tract extend from and to?

A

Extends from M1 (and other motor regions of cortex)
Extends to the spinal cord

29
Q

True or False:

The ventral corticospinal tract descends as crossed fibers

A

False, the ventral corticospinal tract descends as “uncrossed” fibers

30
Q

Where does the ventral corticospinal tract descend?

A

In ventral columns of the spinal cord

31
Q

What do the corticospinal tract innervate?

A

Axial musculature

32
Q

True or False:

The ventral corticospinal tract has few monosynaptic connections

A

True

33
Q

Describe:

How to the ventral corticospinal tract connects to neurons

A
  • Does not directly connect to alpha motor neurons
  • Intermediate neuron is required between the upper and lower (alpha) motor neurons
34
Q

What type of neurons mediate the ventral corticospinal tract?

A

Propriospinal neurons

35
Q

How do propriospinal neurons work?

A

Can bridge across the vertebrae to produce coordinated muscle control

36
Q

True or False:

Propriospinal neurons cannot move single muscle

A

True, it can only allow for moving a group muscles

37
Q

Define:

Polysynaptic connections

A

Multiple connections, not just one connection between upper and lower motor neurons

38
Q

Where do the majority of neurons in the lateral corticospinal tract come from?

A

M1

39
Q

Describe:

How neurons in the lateral corticospinal tract descend?

A

70%-80% of fibers decussate at the pyramids

40
Q

What is the “pyramids”?

A

The “crossing”, where the left brain crosses to right body and the right brain crosses to left body

41
Q

What type of musculature does the lateral corticospinal tract innervate? Give an example

A

Intrinsic musculature (e.x. muscle in your hands/fingers)

42
Q

True or False:

The lateral corticospinal tract has monosynaptic connections

A

True

43
Q

Why does the lateral corticospinal tract has monosynaptic connections?

A

Allows for a neuron in the cortex to have direct control over a muscle
(E.x. power grip, fine grip, precise digit control)

My Packs: (UWO) (KIN 1080) (27 decks)

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