Neural control of movement Flashcards
What are the 4 component parts of movement?
Lower motor neurons
Upper motor neurons
Cerebellum
Basal ganglia
Where are lower motor neuron cell bodies located?
Ventral horn/ brainstem
What do lower motor neurons innervate?
Striated muscles via NMJ
Where are upper motor neuron cell bodies located?
Cortex/ brainstem
Where do UMN synapse?
Interneurons or LMNs
What 2 tracts do UMNs split into?
Pyramidal and non-pyramidal
Where do pyramidal tracts arise from?
Motor cortex
Function of pyramidal tracts
Planning, initiating and directing voluntary movements
Where do extrapyramidal tracts arise from?
Brainstem
Function of extrapyramidal tracts?
Postural control, navigation and antigravity
Name 3 extrapyramial tracts
Rubrospinal, vestibulospinal and reticulospinal tracts
2 general functions of the cerebellum and basal ganglia
Regulate activity of UMNs
Receive information from motor cortex and feed back to it
Is cerebellum or basal ganglia inhibitory?
Basal ganglia
Specific function of the cerebellum?
Coordinates complicated movements, acting as comparator or predictors of movements
Receives input from muscles and compared with intended signal for movement
Function of vestibulo-cerebellum
Balance and posture
Function of spino-cerebellum
Locomotion
Function of cerebro-cerebellum
Skilled motor tasks
What is the function of basal ganglia?
Initiate and maintain motor tasks
Name the 5 basal ganglia
Caudate Putamen Globus Pallidus Subthalmic nucleus Substantia nigra
What 3 main structure makes up the motor cortex
M1- primary motor cortex
PMA- premotor area
SMA- supplementary motor area
Where does motor cortex feed into?
Pyramidal tract
What makes up the association motor cortex?
PMA+SMA
Result of damage to association motor cortex?
Apraxia- loss of ability to carry out familiar learned movements
Function of primary motor cortex?
Voluntary control of movements via LMNs
Function of premotor area?
Planning movements that involve external sensory cues and learned motor activies
Function of supplementory motor area?
Planning movements that involved internal commands or cues
Define tone
Resting level of contraction
Symptoms of hypertonia
Spasticity and rigidity
What causes spasticity
Loss of inhibition of gamma motor neurons.
What tract is involved in causing spasticity
Pyramidal
What causes rigidity
Loss of inhibition of alpha motor neurons
What tract is involved in causing rigidity
Extrapyramidal
What is hypotonia and what causes it
Flaccidity, damage to LMNs
Function of rubrospinal tract?
Gross movements
Facilitates flexor movement
Function of vestibulospinal and reticulospinal tracts?
Posture and balance
5 functions of UMNs
1- excitation 2- inhibition 3- reflex modulation 4- efference copu 5- activation of other brainstem UMNs
What is meant by efference copy?
Internal copy of an outflowing movement producing signal generated by motor system, enabling comparison of actual movement with desired movement
Role of posterior parietal cortex in movement?
Decision to move and functional consequence of action
Role of association motor cortex?
Plans to moves are stored until required
Role of the primary motor cortex?
Instruction to move- activates descending pathways
What happens if there is a signal mismatch detected by cerebellum
Uncoordinated movements
How does brake theory describe role of basal ganglia?
To keep still- brakes on all movements except the reflexes that maintain upright posture
To move- apply a brake to some postural reflexes and release brake on voluntary
How do antigravity muscles differ from other muscles?
More developed with greater tone
What is a neuromuscular disorder?
Condition affecting one or more of the following: muscles, nerves, NMJs, motor or sensory cell body
Describe organisation of the main upprt motor neuron pathways
Corticobulbar: originate from cerebral cortex motor area and goes to brainstem
Corticospinal: originate from cerebral cortex motor areas and goes to spinal cord
Vestibulospinal and reticulospinal: originates from brainstem and goes to spinal cord
Rubrospinal: same as above
What makes up the ready, steady and go of motor cortex?
Ready: posterior parietal cortex (decision to move)
Steady: association motor cortex (sotres plan to move)
Go: primary motor cortex (activates descending pathways)
What is the function of basal gangli?
Initiation and maintenance of motor action- decision making
Scale the strength and response, organise correct sequences of activity
Sign of cerebellum damage?
Ataxis and hypotonia
Sign of basal ganglia damage?
Hyper/hyopkinesia (slow or unwanted movements)
Sign of association motor cortex
Apraxi
