Motor Control Flashcards
Primary motor cortex
Highest level
Projects directly to spinal cord or via corticospinal tract
Regulates the motor tracts that originate in the brainstem
Brainstem
Middle level
Lateral descending system controls distal limbs
Is important for goal-directed movements of hand and arm
Spinal Cord
Lowest level
Contains neuronal circuits that mediate reflexes such as walking
What is the simplest refelx?
Monosynaptic-sensory neurone and motor neurone
What are most reflexes?
Polysynaptic with interneurones
What happens if you artificially stimulate the motor cortex?
Get twitches from the motor areas (simple vowel sounds in the speech motor areas)
Why can babies not walk?
Their corticospinal tracts are not yet myelinated
Basal ganglia and cerebellum
Receive information from many different areas of the cortex and project to motor cortex via thalamus
They are aware of situation the person is in and they monitor commands going down to the muscles to make sure they are appropriate
What happens if the commands are not appropriate?
The basal ganglia and cerebellum step in and calculate correction signals to send back up to the motor cortex for approval before the correction signal is sent to the muscles
Basal ganglia loop only feeds back to ______
The motor cortex
Cerebellum mainly feeds back to ______ but it can send signals down the _____, _____ and onto ____
Motor cortex
Brainstem
Spinal cord
Muscles
Which part acts in an emergency?
The cerebellum as it has the ability to bypass the motor cortex for permission and send the signal anyway
What did Wilder Penfield do?
He was a neurosurgeon who woke patients up during procedures and artificially stimulated parts of the brain to see what they did
He mapped out motor map of the brain by correlating anatomical stimulation and clinical observations on effects of lesions
Where is the motor cortex located?
Just before the central sulcus
What is the motor cortex sometimes called?
The precentral gyrus
To highlight its position
Along the motor cortex there is a orderly representation of the ____
Human body
Why is the finger area so widespread in terms of evolution?
So that damage doesn’t have such a big effect, and you can still use your hands for things for survival like eating etc
The motor cortex’s first neurones are called…?
The upper motor neurones
What do UMNs carry?
Motor commands down through the brain, brainstem and to the spinal cord
Where do the UMNs output and via what?
Output to the lower motor neurones via interneurones
What are the UMNs involved in?
The planning, initiation and direction of movements
What are older UMNs in the brainstem involved in?
Regulation of muscle tone
Posture
Maintaining balance
Orientation of the head and body
Upper Motorneurone pathways
Direct pathways
Indirect pathways
Direct motor pathways
Input to LMN from axons extending directly from cerebral cortex
Indirect motor pathways
Input to LMN from motor centres in the brainstem
What do both direct and indirect pathways govern?
Production of action potentials in LMN
Final common pathway that leads to muscle contraction/movement
What does the basal ganglia consist of?
Caudate Putamen Globus pallidus Substantia nigra Subthalamic nuclei
What does the basal ganglia do?
Helps initiate and terminate movements
Suppresses unwanted movements
Establishes normal level of tone
What does the cerebellum do?
Monitors movements for differences in intended and actual movements
Sends an error signal and tries to reduce discrepancy
Slipping over and correcting posture
