Motor Control and Diseases Flashcards
all movements produced by skeletal musculature are initiated by what?
lower motor neurons.
the spinal cord has central pattern generators meaning…
it can generate behaviours without brain input.
the neurons found in the brain that control motor function are…
upper motor neurons.
what did Fritsch and Hitzig demonstrate in the 1870s when they electrically stimulated parts of dogs’ cortex?
electrical stimulation of that part of the cortex caused contractions of collateral body muscles.
what do we now call the region of the brain that Fritsch and Hitzig stimulated?
the motor cortex.
Sherrington and Penfield in the 1900s correlated stimulation sites with muscle contraction and found that the motor cortex is what?
somatotopically mapped.
lower motor neurons in the ventral horn (of spinal cord) innervate striated muscle to control movement
b
axial muscles control what movement?
trunk movements.
proximal muscles control what movement?
shoulder,
elbow,
pelvis,
knee movements.
distal muscles control what movement?
hands,
feet,
digit movements
each muscle fibre receives input from what type of neuron?
a lower, alpha motor neuron - each one innervates 1 muscle
what is a motor unit?
motor neuron and the muscle fibres it innervates.
what is a motor neuron pool?
all the motor neurons that innervate a single muscle
lower motor neurons receive inputs locally from where?
the spinal cord,
and upper motor neurons.
upper motor neurons project axons to where?
via what?
they project to lower motor neurons via descending tracts in the spinal cord.
what tract in the spine controls voluntary movement?
the Corticospinal Tract (CST).
where is the Corticospinal Tract found?
in the lateral pathway in the spinal cord from the motor cortex.
pyramidal cells of the motor cortex project axons on the Corticospinal Tract.
how many layers is the cortex made up of?
6 layers.
where and what are the main inputs in the motor cortex?
they are stellate cells in layer 4.
where are the main out puts in the motor cortex?
in layers 3, 5, and 6.
the axons of the Corticospinal Tract derive from where and what in the motor cortex?
derive from layer 5 pyramidal cells.
Corticospinal Tract outputs to the upper body originate from where?
the lateral motor cortex.
Corticospinal Tract outputs to the lower body originate form where?
the medial motor cortex.
describe where the axons of the Corticospinal Tract go:
they cross the midline in the pyramidal decussation of the medulla,
they project laterally in the spinal cord,
synapse on lateral lower motor neuron circuits that control distal muscles.
also, there are upper motor neurons in the brainstem, they projects to medial motor pools related to postural movement.
explain the rest of this.
axons from the brainstem project to ipsilaterally in tracts such as:
– the vestibulospinal tract
– the reticulospinal tract,
they synapse on to medial lower motor neuron circuits that control axial muscles.
ventromedial tracts control posture:
what does the vestibulospinal tract control?
head balance and tilting - inputs from the vestibular system.
ventromedial tracts control posture:
what does the tectospinal tract control?
orienting response - inputs from the visual system (via the super colliculus).
ventromedial tracts control posture:
what does the reticulospinal tract control?
control antigravity reflexes.