10 - Neural Control of Movement Flashcards
what are the three general divisions of the brain?
- forebrain
- cerebellum
- brainstem
what is in the forebrain?
- cerebrum
- diencephalon
what are the two divisions of the central nervous system?
the brain
the spinal cord
what are two components of the diencephalon?
thalamus and hypothalamus
the brain stem is continuous with what four components?
the spinal cord, medulla, pons, midbrain
what are the two divisions of the peripheral nervous system?
- afferent division
2. efferent division
the peripheral nervous system consists of __ pairs of crainial nerves and __ pairs of spinal nerves
12 cranial nerves
31 spinal nerves
def: conveys information from the sensors in the periphery to the central nervous ststem
afferent division
def: consists of the somatic and autonomic nervous system
efferent division
def: nerve fibers innervate the skeletal muscle
somatic nervous system
def: nerve fibers innervate smooth muscle and cardiac muscle and glands
autonomic nervous system
what are the two divisions of the autonomic nervous system and their functions?
sympathetic division - fight or flight
parasympathetic division - rest and digest
def: comprise about 90% of the cells within the CNS and occupy about half the volume of the brain
neuroglia
def: a nerve cell, specialized to transmit electrical signals
neuron
def: also known as soma, contains the nucleus
cell body
def: a long fiber that conducts impulses away from the cell body,
axon
def: short projections from the cell body that transmit impulses toward the cell body
dendrite
what is the main purpose of the neuron?
to pass messages or impulses from one part of the body to another
def: discontinuous sheath around the axon primarily composed of lipids and proteins
myelin sheath
def: spaces between the segments of myelin sheath
nodes of ranvier
which nerve fibers have faster conduction velocities? myelinated or unmyelinated?
myelinated nerve fibers
def: the connection of an axon of one nerve to the cell body or dendrites of another nerve
synapse
what are the 3 classes of neurons?
- afferent
- efferent
- interneurons
what kind of neurons carry impulses from the sensory receptors into spinal cord or brain?
afferent neurons
what kind of neurons transmit impulses from the CNS out to the effector organs, muscles and glands?
efferent neurons
what kind of neurons lie entirely within the CNS and account for 99% of all nerve cells
interneurons
def: an appropriate stimulus suddenly causes sodium ions to rush to the inside of the nerve which causes a reversal of polarity
action potential
what are the two types of transmitter substances?
excitatory or inhibitory
the impacts of different transmitter substances are _____ and the will _____
additive and sum
what is spatial summation?
when multiple inputs from different regions add together
what is temporal summation?
when the same input occurs over time fast enough to add up to cause an action potential
what is a neuromuscular junction?
nerve to muscle synapse
what chemical transmitter substance is involved in synapses?
acetylcholine
what are the two enlargements in the spinal cord?
- the cervical enlargement
- the lumbosacral enlargement
what segments does the cervical enlargement extend from?
C4 to T1
what segments does the lumbosacral enlargement extend from?
T11 to L1
def: a network of converging and diverginf nerve fibers, or blood vessels
plexus
what lies in the gray matter?
nerve cell bodies
what constitutes the white matter?
interconnecting tracts of nerve fibers(axons)
what’s the breakdown of the 31 spinal nerves?
12 thoracic 8 cervical 5 lumbar 5 sacral 1 coccygeal
each spinal nerve has a _____ root and a ventral ____ connected to the spinal cord
dorsal root and ventral root
what does the dorsal root contain?
afferent(sensory) fibers that carry information from the periphery to the central
what does the ventral root contain?
efferent(motor) fibers to the skeletal muscle
where are the cell bodies of motor axons that make up ventral roots located?
in the ventral gray horns of the spinal cord
where are the cell bodies of the sensory axons that make up the dorsal roots located?
outside of the spinal cord in the spinal ganglia
def: a collection of nerve cell bodies located outside of the CNS
ganglion
def: transection of the spinal cord results in loss of all sensation and voluntary movement inferior to the point of damage
spinal cord injury
if a patient is quadriplegic, where is their spinal cord transected?
superior to C5
if a patient has a transection above C4, what could happen?
they may die of respiratory failure
if a patient is paraplegic, where is their spinal cord transected?
below the cervical segment
def: deficiency of blood supply to the spinal cord caused by fractions, dislocations, atherosclerosis
ischemia
T or F: when the brain or spinal cord is damaged, in most cases the injured axons can recover
false
def: conduct sensory information to the CNS from muscles, tendons, ligaments and joints
proprioceptors
describe structure of muscle spindles
- several modified muscle fibers
- contained in capsule
- sensory nerve spiraling around its center
how do spindle fibers and regular fibers lie?
parallel to each other
what kind of fibers are spindle fibers?
intrafusal
what kind of fibers are regular fibers?
extrafusal
what do muscle spindles do?
send information to the CNS regarding the degree of muscle stretch
with increasing degrees of stretch of the muscle spindle, the frequency of impulse transmission up the afferent neuron to the spinal cord _________.
increases
what are the 3 ways the muscle spindle can activate the alpha motor neurons to cause muscle contraction?
- tonic stretch
- phasic stretch
- gamma system
tonic stretch concerns…?
the final length of the muscle fibers
how does phasic stretch concern the spindles?
spindle responds to the velocity of the rate of length change
what do gamma efferent fibers do?
innervate the contractile ends of the intrafusal fibers
what two motor neurons coactivate eachother?
alpha motor neurons and gamma motor neurons
gamma system provides the mechanism for maintaining what?
the spindle at peak operation at all muscle lengths
what does the density of muscle spindles depend on?
the degree of control required by a given spindle
where are golgi tendon organs located?
- near the junction of the muscle and tendon
how are golgi tendon organs arranged with the muscle fibers?
they are in series
when a muscle contracts, the GTO is ______
stretched
the firing rate of the GTO is very _____ to changes in the tension of the muscle
sensitive
sensory input from GTO about the tension produced by muscles is useful for actions like…
maintaining a steady grip on an object
what happens when GTO’s are stimulated by excessive tension or stretch?
send sensory information to the CNS, causes the contracted muscle to relax which protects the muscle and its connective tissue
what do joint receptors do?
supply information to the CNS concerning joint angle, acceleration of the joint
the _____ cortex and _______ are the main centers employed in learning new motor skills
cerebral cortex and cerebellum
what information does the right cerebral hemisphere receive?
sensations from and controls from the left side of the body
what information does the left cerebral hemisphere receive?
sensations and movements from the right side of the body
def: located at the rear of the frontal lobe of the cerebral cortex
primary motor cortex
where is the motor homunculus located?
in the primary motor cortex
def: long axons which carry impulses from the primary motor cortex where their cell bodies are located directly to lower motor neurons in spinal cord
corticospinal tract
what kind of movement does the corticspinal system mediate?
performance of fine, discrete, voluntary movements of hands and fingers
def: one of the three higher areas that command the primary motor cortex, located on the lateral surface of each cerebral hemisphere in front of the primary motor cortex
premotor cortex
what is the extrapyramidal tract used for?
route to send impulses from premotor area down to the lower motor neurons of the spinal cord
the pathways in the extrapyramidal tract are more concerned with…..
posture and coordination of large muscle groups
def: located behind the brainstem and under the occipital lobes of the cerebral hemispheres
cerebellum
where does the cerebellum receive signals from?
- from the cerebral cortex and sensory information from receptors in muscles, tendons, joints and skin
what is the function of the cerebellum?
major comparing, evaluating and integrating center for postural adjustments, locomotion, maintenance of equilibrium, perceptions of speed of body
what happens when there’s damage to the cerebellum?
impaired motor control
