W7: Motion Flashcards
define
Motor System
All our muscles and neurons that control them
state
Division of Motor Control (2 Parts)
- Spinal cord (command and control of coordinated muscle contraction
- Brain (command and control and often unpredictable environment)
state
2 Categories of Muscles
- Smooth
- Striated
state
2 Categories of Striated Muscles
- Skeletal
- Cardiac
define
Skeletal Muscle
Constitutes bulk of the muscle mass of the body and functions to…
move bones around joints, move eyes in head, inhale-exhale, control facial expression, produce speech
define
Muscle Fibers
Cells of skeletal muscle
-> Each fiber innervated by a single axon branch from CNS
define
Somatic Motor System
tba
define
Ventral Horn
define
Lower Motor Neurons (LMN)
define
Higher Motor Neuron
define
Final Common Pathway (for Control of Behaviour)
as defined by Sherrington
Y/ N: Are skeletal muscles evenly distributed throughout the body?
No
Y/N: Are lower motor neurons evenly distributed within the spinal cord?
No
state
2 Types of Lower Motor Neurons
(in spinal cord)
- Alpha
- Gamma
state function
Alpha Motor Neurons
Directly trigger the generation of force by muscles
define
Motor Unit
One alpha motor neuron and all the muscle fibers it innervates collectively make up elementary component of motor control
define
Muscle Contraction
Results from the individul and combined actions of motor units.
define
Motor Neuron Pool
Collection of alpha neurons that innervates a single muscle
2 ways
How do alpha motor neurons acheive graded control of muscle contraction?
- Varying firing rate
- Recruiting additional synergistic motor units
define
Size Principle
state
3 Sources of Input to Alpha Motor Neurons
- Sensory input (from dorsal ganglion)
- Upper motor neurons (from upper motor neurons in motor cortex and brain stem)
- Interneurons (in spinal cord)
List Types
Fibers
- Slow (S)
- Fast (F)
Fatigue-Resistant (FR) & Fast-Fatiguable (FF)
define
Excitation-Contraction Coupling
Process by which an AP (excitation) triggers the release of Ca2+ from an organelle inside the muscle fiber which leads to the contraction of the fiber.
state basic principles
Sliding Filament Theory
define
Muscle Spindle
aka Stretch Receptor
Consists of several types of specialised skeletal muscle fibers contained in a fibrous capsule (found deep within most skeletal muscles)
define
Proprioceptors
Group Ia Axons
Group Ib Axons
define
Stretch Reflex
define
Extrafusal Fibers
define
Intrafusal Fibers
list components
Gamma Loop
define
Golgi Tendon ORgans
Another sensor of skeletal muscle, acting like a very sensitive strain gauge monitoring muscle tension (force of contraction)
Located at the junction of the muscle and the tensons are are innervated by group Ib sensory axons
define
Flexor (Withdrawal) Reflex
Factors Influencing Flexor Reflex
Crossed-Extensor Reflex
think: walking / stepping on pin with one leg
Central Pattern Generators
list order, NS areas involves, function
3 Levels of Central Motor System
(hierarchy)
think about the baseball pitcher + batter
- HIGHEST LEVEL - neocortex + basal ganglia - strategy
- MIDDLE LEVEL - motor cortex + cerebellum - tactic
- LOWEST LEVEL - brain stem + spinal cord - execution
How does the brain communicate with the motor neurons of the spinal cord?
Axons from the brain descend through the spinal cord along two major groups of pathways.
list
2 Groups of Pathways (Descending Spinal Tracts)
- Lateral Pathways
- Ventromedial Pathways
