Control of Body Movement Flashcards
the control of body movement exists as a motor control __
hierarchy
the lower level of motor control involves the coordination of tension of ___ and ____ muscle groups
synergistic and antagonistic
low level motor control can execute ___
simple motor subprograms
low level motor control can correct muscle action according to ___
proprioceptor input
give some examples of simple movements that low level motor control can control
straighten legs, turn head
sensory receptors can synapse onto what 2 types of neurons to elicit a motor response?
local circuit neurons in brainstem and spinal cord (that then synapse on motor neurons), or directly to motor neurone in the brain / spinal cord
upper level motor control is responsible for coordination of __
sequences of skilled movements
upper level motor control is responsible for the integration of ____ input
polymodal afferent
upper level motor control is responsible for the correction of ___ according to ___ input
complex motor programs; polymodal
upper level motor control is associated with the __ of complex movements
learning
what brain elements are involved in upper level motor control?
cerebral cortex motor areas, basal nucleus, thalamus, cerebellum, motor centres in brain stem
much of the input from muscle/tendons/skin synapses onto ____
local inhibitory interneurons
a select class of proprioceptions (muscle spindles) can synapse directly onto ___ and directly __ neurons
motor neurons ; depolarize
input from brain motor centers comes from ___ pathways that mostly synapse on ___ interneurons
descending; local inhibitory or excitatory
local interneurons must integrate info from____ and ___ and modualte __
central sources and from the periphery; function of motor neurons
what class of neurons makes up 90% of all neurons?
interneurons
what are local interneurons?
interneurons that are close to the motor neurons they synapse onto
interneurons projecting to distant targets cross the __ and control __ movements
midline; complex
input to motor and local interneurons comes via ___ pathways
descending
somatosensory information from the periphery is sensed by what 2 receptor types? where are each found?
- proprioceptors in muscles, tendon, and joint
2. somatosensory receptors, especially nociceptor
input to motor neurons can come from ___ or ___
somatosensory in periphery or other spinal cord interneurons
___ neurons are at the heart of local circuits in the spinal cord
somatic
somatic neurons provide only output to ___ and constitute ___% of all neurons in the spinal cord
muscle fibers; 10
t/f interneurons are very diverse in function/connectivity
true
what are local pattern generators?
interneurons that initiate repetitive movements as required for walking, swimming etc
monosynaptic reflex arc can synapse to ___ or ___
motor neuron of same muscle ; motor neurone pools of synergistic muscles
primary sensory neurons of muscle spindles are directly connected to ____ neurons in the __ that activate __
motor; spinal cord; the same muscles
if muscle spindles get activated, they will excite __ and lead to creation of __
motor neutrons; action potential
what are the 2 types of motor neurons that primary sensory neurons can activate?
alpha and gamma
what is the function of alpha motor neurons when activated by primary sensory neurons?
excite extrafusal muscles, leading to their contraction
what is the function of the gamma motor units when activated by primary sensory neurons?
excite intrafusal muscles, leading to their contraction
what is the function of muscle spindles?
provide positive feedback for motor neurons of muscles, adjusting the muscle force to the changed load
primary sensory neurons synapse onto synergistic muscles to ___ and also onto local inhibitory interneurons of antagonistic muscle to ___
aide in movement of the main muscle group; suppress action of antagonist to improve movement of main muscles group
what is the required connection to the somatosenosyr cortex that makes it possible to detect changes in load?
axon collaterals of muscle spindle receptors ascending in the dorsal column pathway
muscle spindles are what type of receptor?
proprioceptors
structure of muscle spindles
nerve endings of primary sensory neuron surrounded by connective tissue capsule and extrafusal muscle
muscle spindles can be found wrapped round ___
intrafusal fibers
muscle fibers are activated by __
passive stretch of muscle
t/f muscle spindle reflexes are easy to elicit and interpret and are clinically important
true
give an example of a muscle spindle reflex test and what it is clinically used fr
patellar reflex; helps determine damage to local motor circuit or reflex pathway
when Golgi tendon organs are activated, they provide ___ feedback on motor neurons of the same muscle and ___ contraction. This ic called ___
negative; inhibit ; feedback inhibition
Golgi tendon organs provide excitatory input to neurons innervating the ___ muscles in a process called
antagonistic ; reciprocal stimulation
what causes flexor muscles of shake when over-exerted?
alternating of increases and decrease in motor neurone activity
activation of ___ in the skin of limbs activates the withdrawal reflex
nociceptors
there is a __ reflex in the affected limb of a withdrawal reflex
flexor
in the withdrawal reflex there is excitatory input to motor neurons of the ___ flexor muscle
ipsilateral flexor muscle
in the withdrawal reflex, there is inhibitory input to motor neurons of the ___ extensor muscle
ipsilateral
what is the crossed extensor reflex?
the contraction of the contralateral extensor to allow for withdraw reflex on contralateral side
in the crossed extensor reflex, inhibitory input to motor neurons of the ___ muscle
contralateral flexor
in the crossed extensor reflex, there is excitatory input to motor neurons of the ___ muscle
contralateral extensor
during a withdrawal reflex, the nociceptor sends collateral axons up to the brain via the ___ pathway with the purpose __
anterolateral; alerting the brain that there was an incident
list 4 symptoms of damage to local motor circuits
- weakness or loss of movement of affected muscles
- loss of muscle tone (hypotonia)
- loss of reflexes (areflexia)
- muscle atrophy from disuse
what is the name for muscle weakness?
paresis
the primary motor cortex is major control region for ___
execution of voluntary movements
evidence to support the primary motor cortex being the major control region for voluntary movements
electrical stimulation at certain points results in contraction of different muscles on opposite side
the primary motor cortex is organized in what way?
topologically
parts of the body used for fine motor control are ____ represented. why is this?
positively disproportionately; there are more neurons there
the anterior premotor cortex is responsible for the _____ of movements
initiation
the primary motor and primary somatosensory cortexes are functionally very __ by ___
coupled; projection
t/f the neurons of the premotor cortex are often activated long before movement occurs
true
the premotor cortex is responsible for a selection of ___ movements, ___ and storage of ___
coordinated; learning; motor plans
the pyramidal system is a ___ motor pathway that is important to all __ movement
descending; voluntary
the pyramidal system is made of ___ pathways from neurons in motor cortex to motor neurons in the spinal cord and brain stem
direct
what is the most important tract of the pyramidal system?
corticospinal tract
the corticospinal tract carries info from the ___ to ___ in the ___ that control muscles of ___ and __
motor cortex ; local motor circuits; spinal cord; limbs and trunk
most of the fibers of corticospinal tract decussate at the ___
medulla
left motor cortex controls the __ side of the body
right
what is the second part of the pyramidal system? what does it control?
corticobulba controls the muscles of the head and neck
the pyramidal system forms a visible tract at the height of the ___ in the anterior part that is shaped like an inverted pyramid
medulla in the brainstem
the neurons in the motor cortex that project into the SC / brainstem are layer ___ motor neurons, often called ___to distinguish them from ___ in the SC
5; upper motor neurons; lower motor neurons
most of the neurons of the pyramidal system project to interneurons in the ___ and ___ where their info is integrated with __ info and control lower motor neurons
brain motor enters; SC; peripheral
t/f complex moments requires the use of both the pyramidal and extrapyramidal systems
true
the extrapyramidal system is part of the __ motor pathways
descending
the extrapyramidal system is responsible for ___ movements
involuntary
the extrapyramidal system consists of __ pathways form the motor cortex to the spinal cord neurons controlling the trunk and proximal limb muscles via ___
indirect; motor control enters in the brain stem
what 4 brain components are involved in the extrapyramidal system?
- vestibular nuclei
- reticular formation
- superior colliculus
- red nucleus
the vestibular tract controls __ and __
postural reflexes and maintain balanced position
the reticular formation controls __
muscle tone
the superior colliculus controls __
head ad neck movement towards stimulus
the red nucleus controls
movement of upper extremities in parallel to corticospinal tract
example of a trauma that might cause upper motor disorder
stroke in motor cortex or trauma to upper spinal cord
upper motor neuron disorders are caused by __
damage to motor cortex or corticospinal tract
what is lower motor neurone syndrome?
damage to local motor units in the spinal cord
what are 3 symptoms of upper motor neurone syndrome?
- weakness (paresis) of affected muscle
- loss of fine movements
- spasticity (increased resistance to passive movements
what are there examples of spasticity is upper motor neurone syndrome?
- increased muscle tone (hypertonia)
- hyperactive stretch reflexes
- clonus
what is clonus?
oscillatory contractions and relaxations in response to muscle stretch
what is the hallmark of upper motor neurone syndrome?
clonus
Parkinson’s disease is caused by dysfunction of the
basla nuclei
Parkinson’s disease is a ___ disease
sporadic neurodegenerative
what causes Parkinson’s disease?
progressive loss of dopaminergic neurons in the substantial nigra, leading to decreased corpus striatum activity and higher inhibition of motor cortex
list the symptoms of Parkinson’s
hypokineasia (diminished movements), bradykinesia (slowness), resting tremor and rigidity
what is given as treatment for Parkinson’s? How does it work?
L-DOPA (Levdopa); transformed onto L-dopamine in the brain
the basal nuclei is a group of structures in the ___
fore/mid brain
what structures make up the basal nuclei? (4)
striatum, globus pallidus, subthalmic nucleus, substantia nigra
what is the role of the globes pallid us?
tonically inhibits initiation of movements
inhibition of movement causes by the globes pallid us can be received by actiavtion of the __ by the cortex
striatum
activation of the striatum inhibits the __, which de-represses the __
globus pallidus; motor cortex
activation of the striatum id facilitated by ___ input from the ___
dopaminergic; substantiated nigra
the basal nuclei acts as a __ on all voluntary movements
brake
t/f the basal nuclei must be relieved in order for movement to be initieated
true
neurons in the globus pallidus are __, persistently __ and project to motor nuclei in the __ and persistently ___ thalamic neurons which project into the motor cortex
inhibitory; active; thalamus; inhibit
huntintons disease is a __ disease
inherited neurodegenerative
what causes huntigtons disease?
atrophy of basal ganglia; diminished inhibition of motor cortex resulting in involuntary movements
what are the symptoms of huntington?
jerking movements (dyskinesia), mood change and personality, dementia
what is the treatment for huntigtons? How does it work?
dopamine antagonists; work by reducing striatal function, this making inhibition a little stronger
what are the 4 functions of the cerebellum?
- receive input from motor cortex on intended movement
- receives sensory input on actual movement
- detects differences or motor error between intended band actual
- corrects errors in real time
how does the cerebellum fix motor errors in real time?
through brainstem motor centres and sends information to cortical motor areas for future reference (motor learning)
list symptoms of cerebellar disease (4)
- ataxia
- intention tremor
- unstable posture
- difficulty learning new motor skills
what is ataxia?
jerky, imprecise movements, such as awkward gait
