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A Physiology > 8.8. Supraspinal regulation of muscle functions. Postural reflexes. > Flashcards

8.8. Supraspinal regulation of muscle functions. Postural reflexes. Flashcards

1
Q

I. Supraspinal motor control
1. What are the features of Supraspinal motor control?

A
  • Supraspinal motor control is based in the medulla, midbrain, cerebellum + basal ganglia and the motor cortex
  • The movement can be conscious (lateral pathways) or unconscious (medial pathways).

***Pyramidal + extrapyramidal system terminology is not used here.

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2
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord
1. What are the 2 Major pathways connecting the brainstem and cortex with the spinal cord?

A
  1. Lateral pathways: in the lateral funiculus of the spinal cord. Control conscious manipulation and movement coordination
  2. Medial pathways: in the ventral funiculus of the spinal cord. Deals more with postural reflexes via axial muscles, coordination etc.
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3
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord
2. What are the location and function of lateral pathways?

A
  • in the lateral funiculus of the spinal cord.
  • Control conscious manipulation and movement coordination
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4
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - lateral pathways
3A. What are the 3 main lateral pathways?

A
  1. Lateral corticospinal tract (80%)
  2. Rubrospinal tract
  3. Lateral corticobulbar tract
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5
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - lateral pathways
3B. What are the features of Lateral corticospinal tract (80%)?

A
  • pyramidal decussation.
  • Can have direct or indirect synapse with an α-motor neuron, unique to humans/chimps
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6
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - lateral pathways
3C. What are the features of Rubrospinal tract?

A
  • From red nucleus to the spinal cord.
  • Innervates neck muscles + (some) large arm muscles -> flexor reflexes in upper limb
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7
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - lateral pathways
3D. What are the features of Lateral corticobulbar tract

A

Lateral corticobulbar tract: innervates lower face + tongue

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8
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord
4A. What are the feature and location of medial pathways?

A
  • In the ventral funiculus of the spinal cord.
  • Deals more with postural reflexes via axial muscles, coordination etc.
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9
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - medial pathways
5A. What are the 6 main medial pathways?

A
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10
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - medial pathways
5B. What are the features of anterior corticospinal tract?

A
  • Corticospinal tract (20%)
  • Uncrossed.
  • Innervates medially located muscles (activatebilaterally)
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11
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - medial pathways
5C. What are the features of Vestibulospinal tract?

A
  • Lateral part gets afferentation from semicircular organs
  • medial part gets afferentation from otoliths + SC organs
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12
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - medial pathways
5D. What are the features of Vestibulospinal tract?

A

mostly excitatory

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13
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - medial pathways
5E. What are the features of Medullary-reticulospinal tract?

A

mostly inhibitory

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14
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - medial pathways
5F. What are the features of Tectospinal tract?

A
  • From superior colliculus to spinal cord.
  • Vision + sound stimulus
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15
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - Reticular and vestibular nuclei in the brainstem
6. What are the main features of Reticular and vestibular nuclei in the brainstem?

A
  • There are several nuclei in the brainstem which can affect the movement of our body
  • The brainstem likes to excite motor neurons + interneurons -> get rigidity in the musculature
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16
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - Reticular and vestibular nuclei in the brainstem
7. What are the features of excitatory nuclei?

A
  • Excitatory: vestibular, pontine reticular nuclei
  • Excite neck muscles, axial muscles (which maintain
    posture/balance), anti-gravity muscles, eye movements
17
Q

II. Major pathways connecting the brainstem and cortex with the spinal cord - Reticular and vestibular nuclei in the brainstem
8. What are the features of Inhibitory nuclei?

A
  • Inhibitory: cortex, red nucleus, medial reticular formation
  • These ‘’higher center’’ like to limit the exaggerated rigidity caused by the brainstem
  • If there is no action from the higher centers, the midbrain would like to increase the overall muscle tone
18
Q

III. Postural reflexes
1. What are of Postural reflexes?

A

Postural reflexes (controlled by the brainstem) are automatic movements that control the equilibration we require once upright and moving with the effects of gravity.

19
Q

III. Postural reflexes
2. What is the role of postural reflex?

A
  • They maintain posture, balance and fluidity of movement
20
Q

III. Postural reflexes
3. What is the localization of postural reflex?

A

The localization of these postural reflexes can be visualized with decerebration and decortication which is the separation/cutting of the brainstem from the cortex either at the level of ponto- medullary junction or above the red nucleus (these reflexes also occur with brain injury/lesions)

21
Q

IV. Decerebration
1. What are the features of Decerebration?

A
  • red nucleus is not included
  • The higher centers (cortex, red nucleus, cerebellum) are not able to reduce the overall excitatory effect of the midbrain -> can see the ↑ rigidity in the body:
22
Q

IV. Decerebration
2. Name of the reflex you can observe in Decerebration?

A

Tonic labyrinth reflex

23
Q

IV. Decerebration
3. Describe Tonic labyrinth reflex

A
  • red nucleus is not included
  • The higher centers (cortex, red nucleus, cerebellum) are not able to reduce the overall excitatory effect of the midbrain -> can see the ↑ rigidity in the body:
24
Q

V. Decortication
1. What are the features of Decortication?

A
25
Q

V. Decortication
2. What are the reflexes of Decortication?

A
26
Q

VI. Cerebral cortex
1. What is Motor cortex?

A
  • Motor cortex (precentral gyrus) is the center of voluntary movements, as well as the motivation and planning associated with these movements.
  • This area also regulates muscle tone and movements that need precise sensory-motor coordination.
27
Q

VI. Cerebral cortex
2. What are subdivisions of motor cortex?

A

This functional area is divided into:
- Primary motor cortex – Brodmann 4
- Premotor cortex + supplementary motor area –
Brodmann 6
- Frontal eye movement area – Brodmann area 8

28
Q

VI. Cerebral cortex -Steps in order of motor activity
3A. What are the steps in order of motor activity?

A
  1. Regulates the muscle tone (↓rigidity)
  2. Realization, planning, execution of voluntary movements
  3. Special movements found in cerebral cortex
  4. Cortical postural reflexes
  5. Regulation of movements requiring very precise sensory motor coordination
29
Q

VI. Cerebral cortex -Steps in order of motor activity
3B. What happen in step 1: Regulates the muscle tone (↓rigidity)?

A
  • Cortex would like to suppress the midbrain-originated rigidity (vestibular + pontine
    reticular nuclei)
  • Extensors inhibited + flexors stimulated
30
Q

VI. Cerebral cortex -Steps in order of motor activity
3C1. What happen in step 2: Realization, planning, execution of voluntary movements?

A
31
Q

VI. Cerebral cortex -Steps in order of motor activity - step 2: Realization, planning, execution of voluntary movements
3C2. How does activation of functional areas occur?

A

Association areas (800ms prior to movement)
=> supplementary motor area (500ms prior)
=> premotor area (5ms prior)
=> primary motor cortex activated (0ms)

32
Q

VI. Cerebral cortex -Steps in order of motor activity - step 2: Realization, planning, execution of voluntary movements
3C3. What happen after Activation of premotor cortex?

A

It will activate descending motor pathways via
medial pathways (ant.cs.tract)

33
Q

VI. Cerebral cortex -Steps in order of motor activity - step 2: Realization, planning, execution of voluntary movements
3C4. What happen if we conduct any voluntary movement?

A
  1. body posture stabilized using the medial pathways – anterior corticospinal tract
  2. after few ms, the laterally located muscles which contribute to the movement will be activated by the lateral corticospinal tract => execute movement
34
Q

VI. Cerebral cortex - Steps in order of motor activity - step 3: Special movements found in cerebral cortex
3D. What happen in step 3: Special movements found in cerebral cortex?

A

Some cortical areas are specialized to execute
special movements (eye, hand skills, hand rotation etc.)

35
Q

VI. Cerebral cortex - Steps in order of motor activity - step 4. Cortical postural reflexes
3E1. What are the 3 reflexes found in step 4. Cortical postural reflexes?

A
  • Optical righting reflex
  • Placing reflex
  • Hopping reflex
36
Q

VI. Cerebral cortex - Steps in order of motor activity - step 4. Cortical postural reflexes
3E2. What is the feature of Optical righting reflex?

A

According to many different
visual sensations, we are able to correct our body
position

37
Q

VI. Cerebral cortex - Steps in order of motor activity - step 4. Cortical postural reflexes
3E3. What is the feature of Placing reflex?

A

Placing reflex: causes the ‘’stepping on stair’’-like movement

38
Q

VI. Cerebral cortex - Steps in order of motor activity - step 4. Cortical postural reflexes
3E4. What is the feature of Hopping reflex?

A

if we push someone to the side
=> they will have a jumping-like movement to keep the balance

39
Q

VI. Cerebral cortex -Steps in order of motor activity
3F. What happen in step 5 “Regulation of movements requiring very precise sensory motor coordination”

A
  • We can have colliding information from an object in various situations
    => example: to touch an object behind a prism (prism changes pictures of the object = difficult to touch)
  • conflicting information from visual system and different information from proprioceptors from hand
  • But the cortex should be able to realize how to solve this eventually

A Physiology (88 decks)

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