Neurophysiology 3: Motor System (Lecture 77) Flashcards
What does the two motor system consist of?
Upper Motor Neuron (UMN)
Lower Motor Neuron (LMN)
What does the upper motor neuron control?
Controls LMN, initiates voluntary motor
Where is the Upper Motor Neuron located in?
Within the CNS- “Central”
-Cerebral Cortex
-Brainstem
What does the Lower Motor Neuron innervate, and control?
Innervates skeletal muscles
Spinal reflexes
Where are lower motor neurons located?
Cell body in ventral grey horn of the spinal cord or brainstem—“peripheral”
Compromise peripheral motor neurons
What does conscious motor activity require?
A conductor
What can LMN work independently to produce?
“Automatic” movement
“Stereotyped” movement
What is the “conductor” of the motor system?
Cerebrum
What is the function of the frontal cortex of the cerebrum?
Plans, strategizes, and provides impulse control
Where does the frontal cortex of the cerebrum send its plan?
Basal nuclei
What does the primary motor area initiate?
Voluntary motor movements
What does the primary motor area output to?
Brainstem UMN
Spinal Cord LMN
What are the parts of the basal nuclei (ganglia)
Deep Cerebral grey matter
Striatum—caudate, putamen, accumbens
Globus pallidus
What are not considered basal nuclei, but work in the system?
Substantial nigra
Subthalamic nuclei
What part of the cerebrum is responsible for planning?
Cerebral Cortex
What sends inhibiting signals to thalamus?
Globus pallidus
When the thalamus is in a ________ state, meaning it is _____ sending impulses back to the cerebral cortex.
Static state
NOT sending impulses
What is the striatum a part of?
Basal Nuclei
What/Where does the striatum send signals to?
Inhibitory signals to the Globus pallidus
If you INHIBIT the Globus pallidus, what is the effect?
“Inhibit the inhibitor”
Green light to thalamus to send excitatory signals to cerebral cortex
What are the three pathways of the Descending Motor tracts, that the cerebral motor controls ?
Corticonuclear
Corticopontine
Corticospinal
Where does the Corticonuclear go?
Motor cortex of cerebrum -> brainstem nuclei
**runs ipsilateral
Where does the corticopontine go?
Motor cortex of cerebrum -> pontine nuclei
**pontocerebellar fibers to contralateral cerebellum
Cerebral cortex involved with ________ side of the body
Contralateral side of the body
The cerebellum is involved with the _______ side of the body
Ipsilateral
Where does the corticospinal go to?
Cerebral cortex -> decussate to contralateral corticospinal tract
-“pyramidal tract”
What pathway is responsible for DIRECT communication between cerebral cortex UMN and LMN.
The pyramidal tract
*responsible for fine motor control
What type of activity does the pyramidal tract create?
Voluntary motor activity
What are the three upper motor neurons from the brain stem?
Red nucleus
Pontine and Medullary Reticular nuclei
Vestibular nuclei
Pyramidal tracts have a ____ to _____ connection.
One to One
One upper motor neuron synapses with One lower motor neuron
Extrapyramidal tracts has _____ synapses than actually involved.
More
What is the tract for the red nucleus called? What is a key tract for? What does it Facilitate?
Rubrospinal tract
Key tract for voluntary movement in animals
Facilitate UMN of flexor muscles
What is the key tract for voluntary movements in animals?
Rubrospinal tract
What does the pontine reticulospinal tract facilitate? Inhibit?
Facilitate: LMN of extensor muscles
Inhibit: LMN of flexor muscles
What does the Medullary reticulospinal tract inhibit? Facilitate?
Inhibit: LMN of extensors
Facilitate: LMN of flexors
What two extrapyramidal tracts balance each other out?
Pontine reticulospinal tract
Medullary reticulospinal tract
What does the vetibulospinal tract facilitate?
Facilitate: LMN of extensors
Inhibit: flexors
Where are the lateral corticospinal tract, medullary reticulospinal tract, and Rubrospinal tract in the lateral section of the brain?
Lateral funiculus
Where are the pontine reticulospinal tract and ventral corticospinal tract in the lateral section of the brain?
Ventral funiculus
Which has the largest diameter fibers?
Proproceptive fibers
Which has the smallest diameter fibers?
The nociceptive fibers
Are nocicpetive or proprioceptive fibers faster?
Proprioceptive
Which fibers are least resistent to compressive injury? Which are most resistent?
Proprioceptive
Nociceptive
Which fibers recover first?
Nociceptive THEN motor THEN proprioception
Where are somatic motor neuron cell bodies found?
Ventral horn
Where are visceral motor neuron cell bodies found?
Intermediolateral substance (lateral horn)
The somatic lower neuron ______ the lower motor neuron.
It is a _____ neuron pathway
IS
One
The autonomic motor neuron has an ________ ______.
Autonomic ganglion
Preganglionic neuron
Postganglionic neuron
What is a motor unit?
Somatic motor neuron and the muscle fibers it innervates
What do alpha motor neurons innervate?
Extrafusal muscle fibers
What is the role of alpha motor neurons? (Somatic lower motor neuron)
Contraction of extrafusal muscle fibers
What do gamma motor neurons innervate?
Contractile poles of intramural muscle fibers of the muscle spindle
What is the role of gamma motor neurons? (Somatic lower motor neuron)
Contraction of poles of intramural fibers stretches the muscle spindles
What are two types of somatic lower motor neurons?
Alpha motor neurons (outside the muscle spindle)
Gamma motor neurons (inside muscle spindle)
