Topic 1 - Introduction to Movement Flashcards
Passive Movement
Movement resulting from forces that are external to the body
Ex. Gravity, supportive devices, another body
Active Movement
Movements resulting from muscular contractions
- passive movements can lead to active movements (ex. Stretch reflex)
Reflex Action
Involuntary
Stereotyped response to specific stimulus
Amp of response = amp of stimulus
Voluntary Action
Response that is a result of high-order cognitive processing
Result of a flexible & variable neural network
Characteristics of reflex action
Short latency
Stereotyped (you can predict response based on stimulus)
Conscious awareness does not lrocede response
Involuntary
Response determined by stimulus
Innate (born with reflex response)
Generally protective in purpose
Characteristics of voluntary action
Longer latency
Not stereotyped (adaptable/ can be novel)
Conscious awareness before response
Voluntary
Response related, but not determined by stimulus
Learned (not innate)
Can be protective or harmful
3 other types of actions (not relfexice or voluntary)
- Fixed-action pattern
- Preprogrammed responses
- Rhythmic motor patterns
Fixed-Action Pattern
Not in humans, typically in invertebrates
Relatively stereotyped… fixed latency behaviour triggered by a stimulus
Innate
Amp of response not related to amp of stimulus
Response sometimes not related to stimulus
Preprogrammed Responses
Voluntary actions stored in the CNS and then triggered by a stimulus
(Driving car example.. start-react effect)
Shorter latency than voluntary responses but longer than true reflexes
Amp of responses no relayed to amp of stimulus
Actions sometime not related to stimulus
Rhythmis Motor Patterns
Initiated and temrinated with boluntary command
Once initiated, sequence of contractions are relatively stereotyped and continue in an almost automatic (involuntary) manner
- ex gait locomotion when walking
- once you start walking things begin to feel automatic
Cognitive/reduction Approach to Understanding Movement
Whole is equal to the sum of the parts
Function is derived from understanding the characteristics of the elements
Once you understand individual elements, you can understand whole system
Ex. Compare person with lesion to certain brain area to someone without lesions and compare performance
3 parts of sensation to action loops
- Sensory receptor (PNS)
- Integration (CNS)
- Effectir (PNS)
Feedback Loop (9)
- Sensory receptors and nerves (PNS)
- Stimulas ID (CNS)
- Response selection (CNS)
- Response programming (CNS)
- Motor Plan
- SC (CNS)
- Peripheral Nerve (PNS)
- Muscles
- Action/Output
What 2 systems generate a feedback loop?
- Proprioceptive system (from muscle)
2. Visual system (from eyes)
3 parts of executive functioning
- Stimulus ID
- Response selection
- Response programming
4 rules of a Motor Unit
- Each MU has one MN
- One MN innervates many muscle fibres
- Each muscle fibre is innervatee by only one MN
- Only one kind of muscle fibre per MU
3 types of extrafusal fibres innervated by alpha MNs
- Slow twitch (type 1)
- Fast twitch fatigue resistant (type II a)
- Fast twitch fatigable (type II b)
Main contributer to movement / muscle force
Intrafusal and gamma MN fxn
Role in adjusting sensitivtynof muscles spindles, activation of intrafusal fibre does not lead to muscle force generation
- proprioception
- stretch reflex
During voluntary movements, are both alpha and gamma MNs activated?
Yes
Why are slow Twicth fibres (I) recruited first?
- Smaller components
- smaller cell bodies mean less synaptic output needed to reach action potential threshold - Slower transmission
- Small contraction force bc they are smaller muscles fibres
- Slower contraction speed
Why are fast fatigable (IIb) recruited last
- Larger components
- bigger cell bodies need more synaptic inlut to reach threshold - Faster nervous transmission
- larger diameter means faster transmission - Fast contraction speed
- Larger contraction force bc larger muscles
3 burst of Triphasic EMG
- Agonist (prime mover)
- initial burst to start the movement - Antagonist
- burst to slow down movement as gosl location is approached - Agonist
- burst to finish the movement
Concentric contraction
AGONIST muscle length decreases
Eccentric Contraction
AGONIST muscle length increases
Isometric contraction
Agonist muscle length doesn’t change
Triphasic EMG pattern present
Isotonic contraction
Agonist muscle length may or may not change… force contraction kept constant
No triphase EMG
2 principles of Force generation
- Order of receuitment (size principle)
2. Force-force variability relationship
Force-force variability relationship
How well you can produce a target force over and over again
Greater variability when aiming for higher peak force (greater % of max voluntary contraction)
Why do you get a distribution in peak force?
System noise
Leads to error in recruitment
Random electrical signals that leas to recruitment of random MUs
Size principle
Size of the MU recruited (combined eith system noise) leads to variability in peak force generation
