Wk 10 Motor Systems Flashcards
Give one piece of evidence that we have a hierarchy of motor organisation
We can still execute the same task with a different effector eg writing name w pen strapped to elbow
The motor system is divided into 4 levels. These are:
Motor cortex and brain stem centres (Upper motor neurons)
Spinal cord and brain stem circuits (lower motor neurons)
Basal ganglia
Cerebellum
Within the motor cortex in the posterior precentral gyrus of the frontal lobe, there is a hierarchy from posterior to anterior. Name the 3 areas involved and their locations.
Most posterior: Motor cortex
Medial and more anterior: Supplementary motor area
Lateralised and mor anterior: Premotor cortex
Define the role of the premotor cortex, and restate its location
The premotor cortex, located anterior to the primary motor cortex and lateralised around the supplementary motor area, is believed to help regulate posture by dictating an optimal position to the motor cortex for any given movement
Define the role of the supplementary motor area and restate its location
The supplementary motor area, medial and anterior to the primary motor cortex, seems to influence the planning and initiation of movements based on past experience.
Anticipation of movement triggers neural transmissions in the supplementary motor area.
At the highest level of the hierarchy of motor control, upper motor neurons are part of which 2 systems?
Motor cortex (planning, initiating and directing voluntary movements) and brain stem centres (basic movements and postural control)
At the lowest level in the hierarchy, lower motor neurons can receive information from which 2 inputs?
Upper motor neurons, via local circuitry, or sensory inputs
Name the 2 areas where lower motor neurons are found, and where they project to (forming direct connections)
Spine and brain stem. They project to the skeletal/ peripheral muscles
Lower motor neurons are also known as:
Alpha motor neurons
Name the 2 locations where UMNs synapse with LMNs
Brain stem and spinal cord
Where do corticospinal UPNs, descending in the pyramidal tract, decussate?
The medulla
What is the most important function of the basal ganglia?
Stopping and starting movement
Name the nerve which controls facial muscles.
Cranial nerve VII
A lesion to LMNs (under the pons) would cause what kind of damage?
Unilateral weakness or paralysis on same side as nerve damage
A lesion at the UMN level for the face could have what effect? Explain your answer.
A lesion at the UPN level could cause facial weakness at the lower face (under the eye) contralaterally but spare the forehead area, because UMN control for the upper face is bilateral, whereas UPN control for the lwr face is contralateral.
