Midterm 2 - Unit 5 Lecture 1 Flashcards
How do we produce voluntary movement?
Motor plan – an abstract representation of an intended movement
what are the components of motor plan
specify a goal for the action
create the plan
initiate and execute the movement
compare executed movement with the plan on-line
How does the brain communicate with the motor neurons in the spinal cord?
Axons from the brain descend through the spinal cord along two major group of path-ways:
lateral and ventromedial pathways
Some originate from the cerebral cortex and others from the brain stem
what are the other names for Lower motor Neuron
“Final common pathway”
Alpha motor neuron
where does the Lower motor Neuron originate
Spinal cord and Brainstem
what muscles do Lower motor Neuron innervate
skeletal muscle
Lower motor Neurons are affected by….
descending motor neurons, sensory neurons, and interneurons
where do Upper Motor Neuron originate
the cerebral cortex and travel down to the brain stem or spinal cord
where do the Upper Motor Neuron terminate
Spinal cord and Brainstem
Descending motor pathways are organized into two major groups:
Lateral pathways
Medial pathways
what do the Lateral pathways control
control both proximal and distal muscles and are responsible for most voluntary movements of arms and legs
what do Medial pathways control
control axial muscles and are responsible for posture, balance, and coarse control of axial and proximal muscles.
what is the one lateral motor pathway called
rubrospinal tract
what are the 3 medial motor system
vestibulospinal tract
reticulospinal tract
tectospinal tract
The lateral corticospinal tract contains over _____ of the ________ present in the corticospinal tract and runs the ___________________
90%, fibres, length off the spinal cord
what is the primary responsibility of the lateral corticospinal tract
control the voluntary movement of distal muscles on contralateral limbs.
where does the lateral corticospinal tract originate
the primary motor cortex which lies in the precentral gyrus
what happens when a when a stimulus is engaged in the lateral corticospinal tract
cell body of the lateral corticospinal tract will send an impulse through the tract that will eventually travel to the anterior horn of the spinal cord
from where it will transmit the impulse via lower motor neurons into the muscle fibers
what happens when a motor act is planned to move the leg
an impulse generated from the primary motor cortex will be conducted through the lateral corticospinal tract ipsilaterally
It passes through the posterior limb of the internal capsule
decussates(cross) at the caudal medulla (pyramidal decussation), and then continues to descend contralaterally into the spinal cord
what is the anterior corticospinal tract
is a small bundle of descending fibers that connect the cerebral cortex to the spinal cord.
where does the anterior corticospinal tract originate
primary motor and premotor areas
where do the impulses cross in the anterior corticospinal tract
Remains uncrossed until spinal cord
what is the function of the anterior corticospinal tract
Bilaterally activates interneurons and motor neurons of proximal & axial muscles
what are the two pathways that are considered these direct connections(Cortex directly to spinal cord) with the spinal cord
Lateral Corticospinal Tract
Anterior (Ventral) Corticospinal Tract
where do Brainstem Pathways originate
Originate from Brainstem nuclei to spinal motor neurons