physio exam 2 review ppt Flashcards
(134 cards)
what layer in the motor cortex are the pyramidal cells located
5th layer
what layers have the input signals in the motor cortex
2-4
what type of neurons are the anterior motor neurons in the spinal cord
alpha motor neurons
what are interneurons responsible for
most of spinal cord integrative function (capable of spontaneous activity)
where are renshaw cells located
anterior horns of spinal cord
where do renshaw cells receive collateral branches from
alpha motor neurons
what type of inhibition occurs when renshaw cells transmit inhibitory signals to surrounding motor neurons
lateral inhibition. enhances fluidity of limb movement
what type of inhibition occurs when renshaw cells transmit inhibitory signals to the same motor neuron
recurrent inhibition
what are muscle spindles innervated by
small gamma motor neurons (group 2 afferents)
what type of change do nuclear bags detect
rate of change in muscle length (dynamic change)
what type of change do nuclear chain fibers detect
static change
what are nuclear bag fibers innervated by
1a afferents and dynamic gamma efferents
what are nuclear chain fibers innervated by
group 2 afferents and static gamma efferents
describe dynamic stretch reflex
signals transmitted from primary nerve endings and elicited by rapid stretch or unstretch (opposes sudden changes in muscle length)
describe static reflex
transmitted by both primary and secondary endings and causes degree of muscle contraction to remain relatively constant
what does the muscle spindle over do for its function
prevents jerkiness of body movements (damping)
what does muscle stretch do to firing rate of type 1a afferent fibers
increases firing rate
describe flexor/withdrawal
flexion on ipsilateral side; extension on contralateral side
what motor areas generate a plan for movement
premotor and supplementary motor cortices
what creates the “motor image” of the total muscle movement that is to be performed
anterior part of premotor cortex
what part of the cortex programs complex motor sequences and is responsible for mental rehearsal for a movement
supplementary motor cortex
describe the signal from the posterior motor cortex
to primary motor cortex, the basal nuclei and thalamus, then back to primary motor cortex
define pyramidal system
tracks that pass through medullary pyramids
where do upper motor neurons originate for the pyramidal system
motor cortices