Movement Lecture 1 Flashcards
Non-contractile elements that influence force generation
Cytoskeletal protein
Extracellular connective tissue
Simple description of feedforward & feedback
Feedforward - motor commands
Feedback - Sensory input that determines whether or not the desired state was matched
Forward model anticipate
change in motor system’s state as a result of motor command
Lower motor neurons that innervate axial muscles are? Distal muscles are?
Axial muscles - Medial
Distal Muscles - Lateral
Indices of motor neuron size include?
Cell bodies, axon diameter, amount of force
Two mechanism for regulation of muscle force
Rate coding
Recruitment of motor units
What are the 6 components of motor systems
skeletal muscle
spinal cord
Brainstem
Cerebral cortex
Basal Ganglia
Cerebellum
Motor equivalence
Motor action performed in different ways with the same result
T-Tubules
Sarcolemma that encircle the myofibrils
Errors in Sensorimotor Transformation can also be due to?
Increased difficulty with multi-joint movemenet
What does innervation number indicate?
The fineness of muscle control
What are the 3 principles of motor control
Motor commands arise through sensorimotor transformation
Motor commands are subjective to feedforward and feedback control
Motor commands must adapt to development and experience
Each skeletal muscle fiber is surrounded by?
Endomysium
Properties of Fast Fatigable Motor Nerve
Large diameter
Fastest conduction velocity
Low Excitability - High threshold
Motor Learning involves? and relies on?
involves adapting internal models
relies on different sensory modalities
Skeletal muscle fibers of a single motor unit are usually distributed?
Throughout the muscle
Myasthenia Gravis
- Autoimmune disease characterized by antibodies that bind and degrade ACh receptors
- intermittent weakness increases with activity, decreases, with rest
Processing of information involves what type of connections?
Parallel and Hierarchial
LMNs that support the flexors are? extensors are?
Flexors - dorsal
Extensors - Ventral
Muscles fibers are aligned in parallel bundles that form?
Fascicles
Slow muscle fibers
Slow contraction speed
Low force
Fatigue resistant
exp: maintaining postures
Where is Motor neuron pool located?
ventral horn of spinal cord
Which motor units contract frequently? which motor units contract infrequently?
Slow motor units contract frequently
Fast motor units contract infrequently
Movement inaccuracies arise from?
Variability and Error in Sensorimotor Transformation
Alpha motor neurons (and gamma) are considered as?
Lower Motor neurons, the Final Common Pathway
What are sarcomeres?
Contractile unit of muscle fibers
Sarcolemma
Cell membrane
What is motor neuron pool
a cluster of alpha motor neuron cell bodies that innervate a single muscle
Physical Training can increase?
the rate of motor unit firing action potentials
Spinal Muscular Atrophy
Degeneration of alpha motor neurons due to SMN genetic disease
What happens at increasing length
The decrease in force production by contractile units is offset by passive tension of non-contractile units
Target directed movement tend to follow
a straight pathway with smooth increase or decrease in speed
Reflexive movemenet
Involuntary stereotyped motor response
A single action potential in the alpha motor neuron results in? and what does it elicit?
- results in a single action potential in the skeletal muscle fiber
- elicit twitch contraction
Head region of the Thick filament forms the/
Cross-bridge between myosin and actin
Force varies with
Direction and Rate of Change
CNS forms?
Internal model - the relationship between body and the world
What is changing between contraction and relaxation of skeletal muscle fibers?
Degree of overlap between thick and thin filaments
Extrafusal skeletal muscle fibers are innervated by?
one alpha motor neuron and one neuromuscular junction
Neural noise impacts?
the accuracy of sensory input and motor output
Postsynaptic Membrane is a specialized portion of?
Muscle fiber sarcolemma ( Cell membrane)
Duchenne Muscular Dystrophy (DMD)
Deconstruction of muscle fibers due to lack of the structural protein dystrophin
Extrafusal Skeletal muscle fibers are orientated?
parallel to the long axis of muscle fiber
Voluntary movement is depended on?
context associated sensory inputs
Head region of the thick element has?
ATP, ATPase, and acting binding sites
Guillain-Barre Syndrome
Demyelination of nerves
Usually happens after infection
Reflexive movement is generated by?
Simple neural circuity in spinal cord or brainstem
Definition of Rhythmic movement
Involuntary (voluntary) coordinated repetitive contracting and relaxation of muscles
Which regulation of muscle force is associated with size principle?
Recruitment of motor units
A single action potential is insufficient to?
Release enough calcium
Permit formation of all cross bridges
Reflexive movement is adaptable to?
Change in behavioral goals
Which model is responsible for control?
Which model is responsible for prediction?
Control - Inverse model
Prediction - Forward model
Descending input comes from?
Upper Motor neurons
Inverse Kinematics Transformation
Determine the join trajectories needed to achieve the path to the target
Steps of Excitation-Contraction Coupling
- Action potential in alpha motor neurons
- Ach releases at NMJ
- ACh binds to ACh receptors
- depolarizes sarcolemma
- Action Potential conducted via T-tubules
- Signal SR to release Calcium
- Calcium binds to troponin
- Exposes Actin Binding site
- Sliding filament theory
- Calcium reuptake
Where are the Lower motor neurons that innervate upper limb muscles? Lower limb muscles?
Upper - Cervical enlargement
Lower - Lumbosacral enlargement
Example of rhythmic movement
Locomotion
What are the two types of Internal Models?
- Inverse model
- Forward model
Pathway of alpha motor neurons
- Ventral horn
- Ventral roots
- Spinal Nerves
- Primary Dorsal and Ventral Rami
- Peripheral Nerves
- Terminate at skeletal muscle fibers
Inverse model determines the?
motor command needed to achieve the desired state
What is Rate Coding?
Altering the firing rate of alpha motor neurons
Signs of Neurological conditions
Negative - loss of something
Positive - Appearance of something abnormal
What does Forward model do?
Estimate sensory input based on motor outputs
Use a copy of previous motor command
Signs of Lower Motor Neuron Damage
- Flaccid Paralysis - can lead to muscle atrophy
- Fibrillation - involuntary contractions of motor units
- Hypotonia
- Hyporeflexia
Inverse model and forward model work together to?
Detect and adjust the difference between desired behavior and actual behavior
Fast Fatigue Resistant
Intermediate Contraction Speed, Force, and fatigability
Recruitment of Motor units enables activation in the order of?
Increasing force and fatigability
Inverse Dynamic Transformation
Determine the Joint Torque needed to achieve the Joint Trajectories
Lengthening Contractions (Eccentric)
Force increases and the rate of lengthening increases
What type of movement can be improved with experience?
Voluntary
Myofibrils are composed of?
Series of Sarcomeres
What is the size principle?
Smallest motor units recruited first and Largest motor units recruited last
Neuromuscular junction is a specialized chemical synapse between?
Alpha motor neurons and skeletal muscle fiber
What are the two movement strategies?
- Movement involve activation of many muscles
- Muscle work depends on the pattern of activation
A rapid Series of increased action potentials is able to release?
enough calcium to bind to the troponin sites, maximizing cross bridge formation
Feedforward
- Motor command for initial part of movement
- Based of desired state
- Rapid
Cross Bridge can only be formed when
Thick and Thin Filaments overlap
What are the 3 components of Motor unit
- Alpha Motor Neuron
- Neuromuscular junction
- Extrafusal skeletal muscle fibers
Spinal interneurons receive input from?
Primary sensory neurons, upper motor neurons, collateral from alpha motor neurons
Movement involves muscles that have which 3 functions?
- Produce desired displacement
- Reduce unintended actions
- Establish Rigid Connections
Steps used to generate a particular movement
- Spatial Orientation
- Movement Planning
- Inverse Kinematics Transformation
4, Inverse Dynamic Transformation
Voluntary movement
Intentional, under conscious control of the brain
Skeletal muscles are surrounded by?
Epimysium
Where are thick filaments located? what are they composed of?
- Located in the middle of the sarcomere
- Composed Primarily of myosin molecules
Sarcomeres are consisted of? Extend between?
- Consisted of thick and thin filaments
- Extend between the Z disk
Where are thin filaments located? What are they composed of?
- Located at the end of the sarcomere
- Composed of actin, myosin, and troponin
What does Inverse model do?
Calculates motor output based on sensory input
Fascicles are aligned in parallel forming?
a skeletal muscle
Which 3 factors have an effect on force, velocity, and range of motion?
- Arrangement of the sarcomeres
- Organization of the muscle fibers
- Location of the muscles on the skeleton
Sarcroplasmic Reticulum (SR)
specialized endoplasmic reticulum that surrounds individual myofibrils
Presynaptic Terminal of Alpha Motor Neurons contain?
synaptic vesicles that are filled with ACh
Properties of Slow Motor Nerve
- Small Diameter
- Fast conduction velocity
- High Excitability - Lower threshold
The number and force of each cross bridge is influenced by?
- Calcium concentration in the SR
- Degree of overlap between thick and thin filaments
- Velocity of sliding between thick and thin filaments
Sliding Filament Theory
- Energy released from ATP
- Rowing motion of the myosin cross bridge
- Thin filament sliding relative to the thick filaments
- Shortening of the Sarcomeres
The smaller the innervation number
The finer the motor control
larger number of motor units with smaller number of skeletal muscle fiber
Feedback
- Based on comparison between desired and sense state during the movement
- Error used to adjust output
- slow
Extrafusal skeletal muscle fibers are classified as?
Type I (slow)
Type II (fast)
Postsynaptic membrane has
- Subjectional folds that increase surface area
- ACh receptors
