Section 5a: Motor System and Action Flashcards
what is the top half of brain and brainstem called?
dorsal
what is bottom half of brain and brainstem called?
ventral
what is the top of head called?
superior
what is front of head called (face)
anterior
what is the back of the head called?
posterior
what is bottom of head called?
inferior
what is front of brain called?
rostral
what is back of brain called?
caudal
what are the 5 major divisions of the CNS?
- spinal cord
- cerebrum (aka telencephalon)
- dice-halon
- brainstem
- cerebellum
structure of the cerebrum
wrinkled grey matter 3-5 mm thick
Gyrus - is the ridge of wrinkle
Sulcus - the groove of 2 gyri
components of the cerebrum
- hippocampus: memory and navigation
- amygdala: memory and emotions
- parts of the basal ganglia
what is contained in the diencephalon?
- thalamus- all senses (except smell) go through this
- subthalmaus
- hypothalamus
what is contained in the brainstem
- hindbrain (pons and medulla)
- midbrain (tectum and tegmentum)
- reticular foramen
explain the parts of the hindbrain
pons: main connection to the cerebrum
medulla: keeps you alive
explain the parts of tectum in the midbrain
superior colliculi: relates to movement of the eyes
inferior colliculi: relates to auditory system
what are the parts of the spinal cord?
coccygeal (1)
sacral (5)
lumbar( 5)
thoracic (12)
cervical (8)
what does each section of the spinal cord control?
cerivical - arms (upper limb muscles)
thoracic - trunk, chest and abdominal muscles
lumbar - legs and lower back
sacral - bowels and bladder
what does the white matter and gray matter contain?
gray matter: made of cell bodies
white matter: axons forming the ascending and descending tracts
what comes through the Doral roots in the grey matter?
sensory neurons (afferent)
what comes through in the ventral roots of the grey matter?
motor neurons (efferents)
how are spinal motor neurons organized in spinal cord?
aka alpha motoneurons
- the cell bodies like in longitudinal column called motor nuclei
- motor neurons for proximal muscles are medial
- motor neurons for distal muscles are lateral
what informations does the ascending and descending tracts carry?
ascending tract: mostly sensory
descending tract: motor
define what a motor unit represents and how they are organized?
it is the motor neuron and the muscle fibre its connected to
all the muscle fibres connected to one neuron are the same fibre type (fast or slow twitch)
which type of motor unit is activate first and why?
slow twitch is activate first as they fatigue later, this saves energy of the muscle
how does the connection of motor neuron to muscle fibre work?
each muscle fibre is connected to one neuron but one neuron can be connected to many muscle fibres
what is a synaptic bouton?
it multiple bundles that come off the axon at the end plate
what’re the 3 ways different ways the nervous system can increase muscle force
- recruiting different size motor units
- activating more motor units
- increasing frequency of action potentials in the muscle fibre
How does activating more motor units increase muscle force?
(what is the relationship between contractile force and motor unit size)
large motor units have more muscle fibres
so large muscles have many motor units
MU Y: 7 fibers
MU X: (5 fibers)
tension is increased by recruiting more motor units
How can recruiting different size motor units increase muscle force?
low frequency of stimulation from CNS activates smaller motor units as they have a smaller threshold of activation
As the stimulation increases, it activates the large motor units as they have a higher threshold. Large motor units increase muscle force
how does increasing frequency of action potentials in the muscle fibre increase muscle force
as the frequency increases the it eventually reaches maximum force generation, The slower the movement, the more stimulation which means higher frequency and larger motor units are recruited.
Why do neurons form simple and complex neural pathways?
they have the ability to change other neurons ability to transmit information
explain a why a monosynaptic stretch reflex happens and how?
it is used to maintain muscle length or position
- when muscle is stretched 1a afferent neuron directly signals the alpha motoneuron (monosynaptic) to contracts the muscle
- at the same time the 1a afferent neuron signals the 1a inhibitory interneuron to inhibit the alpha motorneuron for the antagonist muscle from firing (a disynaptic pathway)
explain a why withdrawal (flexion) reflex happen and how?
used to remove limb from painful stimulus
- the painful stimulus is detected by the free nerve ending and sent through a sensor neuron
- pain and postural stimulus is sent to the brain through an ascending pathway
- at the same time, withdrawal stimulus is sent through a polysynaptic pathway to the muscles
explain a crossed extension reflex and why happen
used to increase support when withdrawal flexion throws body of balance
- when a postural stimulus is received to the brain, motor neurons are on opposite limb are sent a stimulus to maintain balance
explain sensory feedback control
descending commands can override the reflexes when needed to maintain task
explain supraspinal modulation
supraspinal modulation can desensitize/sensitize an area to a stimulus to decrease/increase frequency needed for action to occur
explain the components postal reflex
when balance perturbed
- SLR (short latency reflex): monosynaptic reflex
- MLR (medium latency reflex): integration of information from brainst;em
- LLR (long latency response) cortex information integrated as well (not really a reflex)
explain how reflexes are adaptable
task dependant reflexes will stop movement of a muscle that is needed to maintain task
what is a CPG?
central pattern generator, it is a neural network that has the ability to perform a rhythmic pattern of motor activity (usually continuous task) after being triggered sensory input (doesn’t need sensory to maintain it)
how does a CPG work and where are they found?
found in the cerivla and lumbar sections or the spinal cord, the flexor and extensor circuits will mutually inhibit each other alternation the activation of each
example walking: so that a swing and stance phase occur
