Motor Action and Control Part 1 Flashcards
What are the two basic aspects of movement control?
Sensory and Motor
What does the Final Common Pathway involve?
Lower motor neurons
What is the function of sensory processing?
To create an internal representation of then outside world or state of the body
What is proprioception?
The conscious aware of body position and movement
What are Pain and Thermal Sensations?
Tissue Damaging and the Slowest Impulses
What does motor processing begin with?
Internal Representation - having a particular idea of the desired movement
What is psychophysics?
The relationship between the physical characteristics of a stimulus and the attributes of its perception.
What are the four basic stimuli?
- Electromagnetic Waves (light)
- Mechanical Air Vibrations (sound)
- Internal and External Chemicals
- Mechanical Deformations
What does electromagnetic waves influence?
Reflexes, reactions and conscious decisions
What does mechanical air vibrations influence?
Head Position and Equilibrium.. sense of balance (ears)
What do external and internal chemicals influence?
External - Olfaction (sense of smell)
Internal - Metabolic End products (lactic acid)
Muscle Fatigue - Force Decrease, Pain/Swelling
What does mechanical deformations influence?
External - Skin Stretch or Compression
Internal - Muscle Force and Stretch Speed
What are the four elementary attributes of sensory psychophysics?
1.) Modality
2.) Intensity
3.) Location
4.) Duration
What is Motor Psychophysics?
Motor Response to Sensation and Perception
What is Modality (quality)?
Touch (stretch, force), vision, etc.
What is Intensity?
Proportional to the Type and Number of Neurons Discharged
What is Location?
Body part location, depth perception (vision)
What is Duration?
Sensory Accommodation; i.e, fast adapting vs slow adapting
What are the three types of motor actions?
1.) Reflex Responses
2.) Rhythmic Motor Patterns
3.) Voluntary Movements
What are reflex responses?
- Least affected by voluntary control
- Rapid, Stereotyped Movements
- Controlled by the eliciting stimulus
What are the rhythmic motor patterns?
- Walking, Running, Chewing
- Combines features of Reflexive and Voluntary Actions.
What is Voluntary Action?
Initiates action
What is reflexive actions?
Maintains the initiated actions
CPGs.. central path generators.
What is Voluntary Movements (Motor Acts)?
Purposeful.. goal oriented (not rhythmic)
Learned.. skill improves with practice and its practice comes less conscious direction
What are Motor Acts continuously updated with?
Sensory Information, proprioception, visual and auditory
What are 3 tasks of the motor system?
1.) Must convey accurately timed commands to MANY motor neurons
2.) Must consider body mass distribution, plan postural adjustments
3.) Must consider the state of the motors
What works to convey accurately timed commands to MANY motor neurons?
Agonists and Antagonists
How does body mass distribution, plan postural adjustments?
Walking..opposite bi-lateral muscle activation.
How must we consider the state of the motors?
Joint position… extreme range of motion vs. mid-range
Where are the muscles the strongest?
Mid-range of motion, and mid-length
What is the metabolic state?
Dependent on the state of fatigue
What is the motor side of the nervous system?
Adjustments to mechanically failing muscle (muscle fatigue)
What does an increase in neural drive do?
Increase motor activation in attempt to maintain an ABSOLUTE force output
What are the 3 levels of movement control from highest hierarchy to lowest?
1.) Cerebral Cortex
2.) Descending systems of the Brain Stem
3.) Spinal Cord
What are 2-sub cortical, independent systems?
The cerebellum and basal ganglia
What is the Cerebellum?
Improves accuracy of movement (lots of neural information)
Descending Signal Modification - input from sensory signals from original action
What is the Basal Ganglia?
Receives input from ALL cortical areas
Projects neurons TO frontal cortex (involves in motor planning).. movement initiation impaired
What is the Spinal Cord?
- The lowest level in the hierarchy
- Involves simultaneous activation and inhibition of different muscle groups.
What is the spinal cord coordinated by?
Local spinal circuits, and higher level..descending signals
What are motor neurons?
The final common pathway (all pathways converge into motor neurons)
Where do inputs come from?
- Same muscle, antagonist muscle, opposite limb muscle
- Upper levels
- Excitatory (activation)
- Inhibitory
What does the Brain Stem consist of?
2 parallel neuronal systems…medial and lateral
What does the Medial Pathway control?
- Posture
What does the Medial Pathway integrate?
Visual and vestibular input (inner ear) with somatosensory information
What does the Medial Pathway control?
Upright body position
What is the Medial pathway primarily?
Axial Muscles
What does the Lateral Pathway control?
Distal muscle of limbs and discrete movements
What does the Cerebral Cortex consist of?
Primary Motor Area
Pre-motor cortex
Supplementary Motor Area
What do all aspects of the Cerebral Cortex project to?
To the spinal cord via the corticospinal tract and indirectly through brain stem motor neurons
Where do the Pre-motor Cortex and Supplementary Motor Area plan and coordinate?
Complex movement sequences and receives information from posterior parietal area and projects to the primary motor area.
What is the Primary Motor Cortex (Area 4)?
Receives input..speed and position of movement
- Proprioceptive input (motor neuron activation)
Lesions would cause muscle weakness
What is Area 6 - Premotor and Supplementary Motor Areas?
Neurons project to the primary motor cortex
Subcortical structures and spinal cord
Lesions would cause inability for movement strategy
What is the Muscle Spindle?
Type Ia and Type II receptors
Has dual innervation (sensory and motor)
What are the Golgi Tendon organs?
Type Ib receptors
What are Joint Structures?
Golgi-like and skin-like receptors (give rise to reflexes)
What is the Sensory Cortex?
S1 - activation of neurons, external state
Feedback from Sensory Input
What is the Thalamus?
Relay Nuclei
Projects to sensory cortex and cerebellum
What are skin receptors?
Fast Adapting
Slow-Adapting
What is the Dorsal Root of the Spinal Cord?
Afferent (Sensory)
What is the Ventral Root of the Spinal Cord?
Efferent (motor)
What are the two types of neurons whose cell bodies reside in grey matter of spinal cord?
Interneurons, and lower motor neurons
Where does Decussation for Pain Occur at?
The Spinal Level
What is the Motor Neuron Pool?
Refers to Clusters of Motor Nuclei residing in the ventral horn (extends 1 - 4 vertebral columns (longitudinal)
What is an example of a motor neuron pool?
Knee extension
Muscle (Quadriceps femoris)
What is the first rule of spinal cord organization?
Proximal Distal Rule
What does Proximal-Distal rule state?
Proximal Muscles… Axial-Medial Motor Neuron Activation
Distal Muscles… extremities..lateral motor neuron
What is the second rule of spinal cord organization?
Flexor-Extensor Rule
What does Flexor-Extensor Rule State?
Extensor Muscles… more ventral location
Flexor Muscles… more dorsal location
What are the Extensor and Flexor muslces all contain within?
Ventral Horn
