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Body & Behaviour > Problem 5 > Flashcards

Problem 5 Flashcards

1
Q

Motor Unit

A

comprises:

 - -> motor neuron
 - -> all of the individual skeletal muscle fibers it innervates
  • differ in number of muscle fibers
    • -> units with fewer fibers have a higher degree of selective motor control (ex. fingers, face)
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2
Q

Muscle contraction

Process

A
  1. Motor neuron fires
  2. ACh is released at neuromuscular junctions
  3. ACh activates motor-end-plate on each muscle fiber
  4. Contraction of the fibers
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3
Q

Fast muscle fiber

A

contracts + relaxes quickly

--> fatigue quickly because poorly vascularized (few blood vessels - pale)
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4
Q

Slow muscle fiber

A

slower + weaker

 --> contraction is more sustained because richly vascularized
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5
Q

Flexor

A

acts to bend or flex a joint

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6
Q

Extensor

A

act to straighten or extend a joint

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7
Q

Synergistic Muscles

A

two muscles whose contraction produces the same movement

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8
Q

Antagonistic Muscles

A

two muscles whose contraction produces opposite movements

ex.: biceps, triceps

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9
Q

Isometric Contraction

A

Contraction of a muscle without movement

–> no change in the length of the muscle

ex.: plank, wall sit (no movement)

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10
Q

Dynamic Contraction

A

Contraction of a muscle resulting in movement

–> change in the length of the muscle

ex.: squats, tricep dips (movement)

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11
Q

Principles of the sensorimotor system

A
  1. hierarchally organized
    • -> the higher the levels of the hierarchy the more complex functions they perform
  2. functionally segregated
    • -> each level is composed of different units each of which perform different functions
  3. Information flows down ( Somatosensory S - up )
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12
Q

Structure of the Sensorimotor System

A
  1. Association Cortex
    • Posterior parietal association cortex
    • Dorsolateral prefrontal association cortex
  2. Secondary motor cortex
  3. Primary motor cortex
  4. Brain stem motor nuclei
  5. Spinal motor circuits
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13
Q

Information transmission in Sensorimotor System

A
  1. Posterior parietal AC supplies Dorsolateral prefrontal AC + Secondary MC with information
  2. Dorsolateral prefrontal AC + Secondary MC issue commands based on that information
  3. Commands are forwarded to the primary motor cortex
  4. Commands are now distributed over four main channels to the spinal sensorimotor circuits
  5. Spinal sensorimotor circuits direct the activities of the muscles
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14
Q

Role of the Posterior parietal association cortex

A

integrating the information of

 1. the original positions of the parts of the body that are to be moved 
 2. the positions of any external objects the body is going/might interact with
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15
Q

Where does the Posterior parietal AC receive its information from ?

A
  • visual cortex
  • auditory cortex
  • somatosensory
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16
Q

Where does the Posterior parietal AC send its information to ?

A

Dorsolateral prefrontal cortex and secondary motor cortex

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17
Q

Appraxia

A

disorder of voluntary movement

–> damage to Posterior parietal AC

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18
Q

Contralateral Neglect

A

Disturbance of a patients ability to respond to stimuli on the side opposite to the side of a brain lesion

–> damage to Posterior parietal AC

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19
Q

Role of the Dorsolateral prefrontal association cortex

A

Decision to initiate voluntary movement

20
Q

Role of the Secondary motor cortex

A

involved in the programming of specific patterns of movement after taking general instructions from the dorsolateral prefrontal AC

 --> its neurons become active prior to the initiation of the movement and continue the activity throughout the movement
21
Q

Mirror Neurons

A
  • fire when and individual performs a particular goal directed movement
  • or when an individual observes the same goal directed movement performed by others
22
Q

Role of the primary motor cortex

A
  1. Initiating body movements
  2. moving body parts independently (ex.: fingers, toes)

Major point of

 - -> convergence of cortical sensorimotor signals 
 - -> departure of sensorimotor signals from cerebral cortex
23
Q

Somatotopic organization

A

organization according to the map of the body

ex.: stimulation of the face elicits face movements

24
Q

Astereognosia

A

Inability to identify objects by touch

--> damage to primary motor cortex
25
Q

Role of the cerebellum

A
  1. motor learning and learning sequences of movements (timing)
  2. correcting ongoing movements that deviate from their intended course
26
Q

Role of the Basal Ganglia

A

habit learning

–> acquired gradually

27
Q

Descending motor pathways

A

The primary motor cortex sends neural signals via 4 different pathways to the motor neurons of the spinal cord

 - -> 2 pathways descend into the dorsolateral region of the spinal cord 
 - -> 2 pathways descend into the ventromedial region of the spinal cord
28
Q

Dorsolateral corticospinal tract

Procedure

A

Axons descend directly into the spinal cord

  1. Groups of axons descend through medullary pyramids
  2. Axons decussate (kreuzen) and continue to descend into the contralateral dorsolateral spinal white matter

=> descend contralateral into distal (far) muscles (e.g.: fingers, toes)

29
Q

Dorsolateral corticorubrospinal tract

Procedure

A

Axons synapse in the brain stem on neurons that in turn descend into the spinal cord

  1. Group of axons synapse in the red nucleus of the midbrain
  2. Axons decussate and descend trough medulla
  3. Some of them terminate in the nuclei of the cranial nerves that control muscles of the face
  4. The rest continues to descend into the dorsolateral portion of the spinal cord

=> descend contralateral into distal (far) muscles (e.g.: fingers, toes)

30
Q

Ventromedial Corticospinal tract

Procedure

A

Axons descend directly into the ventromedial areas of the spinal white matter

=> descend ipsilaterally into proximal (near/close) muscles of trunk and limbs

31
Q

Ventromedial cortico brainstem spinal tract

Procedure

A
  1. Axons feed into a complex network of brain stem structures
  2. Axons then descend into ventromedial portion of the spinal cord

=> descend ipsilaterally into proximal (near/close) muscles of trunk and limbs

32
Q

Tectum

A

receives auditory and visual information about spatial location

 --> brainstem structure that interacts with the VMCBS
33
Q

Vestibular nucleus

A

receives information about balance

 --> brainstem structure that interacts with the VMCBS
34
Q

Reticular formation

A

contains motor programs that regulate complex movements (e.g.: swimming, walking, jumping)

 --> brainstem structure that interacts with the VMCBS
35
Q

Motor nuclei of the cranial nerves

A

control the muscles of the face

 --> brainstem structure that interacts with the VMCBS
36
Q

Golgi tendon organs

A
  1. Provides CNS with information about muscle tension
  2. Excite inhibitory interneurons to relax the muscle
    • -> when contraction is so extreme that theres a risk of damage
  • embedded in tendons
37
Q

Tendon

A

attach/bind muscle fibers to a bone

38
Q

Muscle spindle

A
  • respond to changes in muscle length

embedded in muscle tissue itself

39
Q

Patellar tendon reflex

Procedure

A
  1. Strike to the tendon of a knee
  2. Extensor muscle of the thigh is stretched
  3. Thigh stretch –> stretches the muscle spindle stretch receptors
  4. Receptors initiate a volley of APs which are carried from the stretch receptors via the dorsal root into the spinal cord
  5. APs excite the motor neurons in the ventral horn of the spinal cord
  6. the motor neurons respond by sending APs back to the muscle who originally excited them
  7. The arrival of impulses back at the starting point results in a contraction of the compensatory muscle + sudden leg extension
40
Q

Withdrawal reflex

A

protection mechanism

41
Q

What is Reciprocal innervation ?

A

“When one muscle contracts, the other relaxes”

–> flexors and extensors can’t act at the same time

42
Q

Reciprocal innervation

example with withdrawal reflex

A

Touching something hot:

  1. Pain from heat arrives at the hand
  2. Signals excite excitatory + inhibitory interneurons
  3. Excitatory interneurons excite motor neurons of the elbow flexor
  4. Inhibitory interneurons inhibit neurons of the elbow extensor
43
Q

Motor equivalence

A

same basic movements can be carried out in different ways involving different muscles

44
Q

Shifiting control to lower levels

A

frees up the higher levels of the system to deal with more esoteric aspects of performance

45
Q

Response chunking hypothesis

A
  • practice combine the central sensorimotor programs that control individual responses into programs that control sequences (chunks) of behavior
    ex: novice typist –> each response necessary to type a word is triggered + controlled

skilled typist –> sequences of letters are activated as a unit

Body & Behaviour (9 decks)

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