sensory and motor neuroscience (intro to motor control) Flashcards
explain the definition of functional segregation
the motor system is divided into a number of different areas that control different aspects of movement
explain the definition of hierarchical organisation
the motor system is organised in a hierarchical fashion
sensory ___ enter the spinal cord via the dorsal root
sensory afferents enter the spinal cord via the dorsal root
sensory afferents enter the spinal cord via what
the dorsal root
sensory afferents enter _____ via the dorsal root
spinal cord
motor neurons leave the spinal cord via what
ventral root
what neurons leave the spinal cord via the ventral root
motor neurons
alpha motor neurons (or lower motor neurons) innervate what
skeletal muscles
what neurotransmitter do alpha motor neurons release
acetylcholine
at what synapse do alpha motor neurons release acetylcholine
neuromuscular junction
what neurons innervate skeletal muscle
alpha motor neurons
what neurons are clustered into spinal motor nuclei
alpha motor neurons
alpha motor neurons are clustered into what
spinal cord nuceli
all of the motor neurons in a nucleus innervate what
a single muscle
_____ in a nucleus innervate a single muscle
all of the motor neurons in a nucleus
each individual muscle fibre is innervated by how many motor neurons
each individual muscle fibre is innervated by only one motor neuron
each motor neuron can innervate how many fibres
many
a motor neuron and all of the fibres it innervates is known as what
a motor unit
define a muscle twitch
when a motor neuron fires an action potential, the muscle fibres of the motor unit contract, then relax
what does this statement explain
when a motor neuron fires an action potential, the muscle fibres of the motor unit contract, then relax
a muscle twitch
what is a tetanus
if the firing rate is high enough, an individual muscle twitches fuse together forming a tetanus
a continuous contraction
the higher the firing rate of a tetanus the
(finish the sentence)
the higher the force of contraction
one way of increase the force of contraction is increasing the firing rate, what is another way
recruiting more motor units
in what order are motor neurons recruited
small fine units - requires activation of S units
as more force is required, increasing number of F units
what is the difference between S and F units
F units contain larger numbers of muscle fibres
what kind of athlete would require larger number of S units
marathon runner
why would a marathon runner require more S units
(S)low contraction speed, highly fatigue resistant
contains I slow-twitch muscle fibres
motor neurons have small cell bodies and dendritic trees
what does a motor neuron look like
small cell bodies and dendritic trees
how is FR known as
fast fatigue resistant
what kind of athletes would need FR
800/1500 metre runners
why would a 800/1500m runner need FR
fast contraction speed
intermediate force
fatigue resistant
contains type IIa (fast twitch, high fatigue resistant
motor neurons have larger cell bodies
what is FF motor unit
Fast fatiguable
what athletes would require FF motor units
60/100m runners
why would 60/100m athletes require FF motor units
fast contraction speed, low fatigue resistant
contain type IIb/x
fast twitch low fatigue resistant
muscle fibres have large cell bodies
list the types of motor units and arrange them regarding the size of their cell bodies (smallest to largest)
S - small cell body and dendritic trees
FR - larger cell bodies
FF - large cell bodies
explain the size principle
orderly activation of motor units according to their size of cell bodies of their alpha motor units
-> smaller motor neurons are activated first
in the size principle, why are smaller motor neurons activated first
small surface area
-> increased membrane resistance which means more rapid depolarisation due to
V=IR
what is the speed of reflexes
rapid -> automatic
how are reflexes generated
by the circuitry of the spinal cord