Introduction to Motor Systems

Question 1

feedback control

Answer 1

use of sensory information during movement to make corrections to the ongoing movement

Question 2

feedforword control

Answer 2

anticipate the effect of a particular movement

Question 3

gamma motorneuron

Answer 3

provide motor supply of intrafusal muscle fibers

Question 4

skeletal-fusimotor neurons

Answer 4

innervate both extrafusal and intrafusal fibers (sometimes called beta innervation)

Question 5

what are the functional componetns of a motor units

Answer 5

cell body of a motor neurons
axon
neuromuscular junction
muscle fibers

Question 6

where do you find small motor units

Answer 6

where we need fine control of a muscle

Question 7

where would you find large motor units

Answer 7

large strong muscles

Question 8

what does poliomyelitis affect

Answer 8

very large motor unitsin affected muscles since surviving motor neurons adopt orphaned muscle fibers

Question 9

what is post-polio syndrome caued by

Answer 9

stress on surviving motor neurons after others have died

Question 10

henneman’s size principle

Answer 10

recruit smaller neurons before larger ones

Question 11

what does denervation of a muscle cause

Answer 11

prodound muscle atrophy

Question 12

characteristics of LMN disease

Answer 12

muscle atrophy
decreased tone
weak/absent stretch reflexes
fasiculuation/fibrations

Question 13

are benign fasciculations a sign of LMN disorder?

Answer 13

nope

Question 14

flaccid paralysis

Answer 14

loss of voluntary and reflexes

Question 15

what happens if you completely transect the spinal cord

Answer 15

permanent total paralysis
permentat anethesia
spinal shock

Question 16

spinal shock

Answer 16

temporary loss of spinal cord reflex acitivty that occurs below a total spinal cord injury

Question 17

lower motor neurons

Answer 17

directly inenrvate skeletal muscles

Question 18

are upper motor neurons technially motor neurons

Answer 18

no

Question 19

upper motor neurons

Answer 19

neuron in a higher motor area that synpases on a LMN or an interneuron that synpases on a LMN

Question 20

spasticity

Answer 20

motor disorder characterized by a velocity dependent increase in tonic stretch refelxes with exaggerated tendon jerks, get hyperexcitability of stretch reflex

Question 21

voluntary movement

Answer 21

purposeful, learned, improve with practice

Question 22

reflex responses

Answer 22

involuntary

automatic response to external stimuli

Question 23

rhythmic motor patterns

Answer 23

require no higher level thinking, like walking or chewing

Question 24

what do alpha motor neurons innervate

Answer 24

extrafusal skeletal muscles

Question 25

how does graded muscle contraction increase muscle force

Answer 25

recruitment or multiunit summation

increase firing rate of activated motor units

Question 26

would you get UMN syndrome if just the corticospinal tract was damaged

Answer 26

no

Question 27

which are faster, alpha or gamma motor neurons

Answer 27

alpha

Question 28

motorneuron pools

Answer 28

all the neurons that control 1 muscle

Question 29

where are alpha motor neurons located

Answer 29

anterior horn

Question 30

what are the permanent effects of transection of spinal cord

Answer 30

loss of voluntary movement

loss of true sensation