Motor Control Unit 1

joint

point at which a segment moves

sarcomere

major contractile unit of a muscle

myosin

thick filament of sarcomere

actin

thin filament of sarcomere

concentric contraction

causes joint action (shortening)

eccentric contraction

opposes observed joint action (lengthening)

isometric contraction

holds joint position (static)

ions

atoms with a charge; electrically charged molecule

potential difference

difference in electrical energy on either side of the membrane

voltage gated channels

protein in cell membrane that opens when electrical charge changes

dendrites

signal receivers of neuron

soma

body of neuron

axon

transmits action potential for output

synapse

junction where signals are transmitted to another excitable cell

sarcoplasmic reticulum

part of muscle fiber that contains calcium which releases when membrane is excited

troponin

regulatory protein on thin filament that blocks actins binding sites

tropomyosin

regulatory protein that troponin is on which is moved by calcium

muscle twitch

involuntary muscle fiber/muscle contraction that occurs when an action potential reaches the SR

motor unit

functional unit of nervous system and muscle

discharge rate

rate of action potentials descending motor neurons (high when frequency of AP is high)

afferent

input to CNS from sensory receptors

efferent

output from CNS to effector organs (muscles)

motoneural pool

all motor neurons innervating a single muscle

renshaw cells

inhibitory interneurons

recurrent inhibition

negative feedback loop in spinal cord where an active motor neuron suppresses its own activity through intermediary nerve cell

reciprocal inhibition

neurological process where CNS makes one muscle contract while telling opposing muscle to relax

monosynaptic reflexes

only one intraspinal excitatory connection (stretch reflex)

oligosynaptic reflex

involves a small number of intraspinal connections (golgi tendon organ reflex)

polysynaptic reflex

involves many intraspinal connections

muscle spindles

embedded throughout muscle and sense muscle length and rate of muscle stretch

golgi tendon organ

embedded within tendon interlaced between collagen fibers and senses muscle force/tension

climbing fiber

creates hundreds of synapses on purkinje cells; transmits an obligatory signal to purkinje cells

mossy fiber

receives sensory information, Transmits sensory information to parallel fibers through granule cells, excites cerebellar nuclei

purkinje cell

innervated by climbing fibers; the fibers transmit inhibition signals to cerebellar nuclei

parallel fiber

provides convergence sensory signaling to purkinje cells

cerebellar nuceli

Receives both excitatory and inhibitory signals to smooth movement timing and control

premotor cortex

integrates sensory information into motor commands (assists with motor planning)

supplementary motor area

Plans sequencing and initiation of motor commands (executive control)

primary motor cortex

brain area that sends efferent signals to motoneuronal pools within the spinal cord

parietal cortex

integrates and processes sensory information

corticospinal tract

the collection of efferent axons that descend the spinal cord from the brain; sends voluntary motor signals to spinal cord

basal ganglia

located withing center of brain; plays a major role in initiating and inhibiting movement; involved in motor learning through dopamine modulation and long term potentiation

cerbellum

inferior portion of brain responsible for coordination and smoothing of movement; integrates sensory information to correct errors and ensure smooth coordination movement