Motor Control and the Corticospinal Tract

Question 1

what is the direct pyramidal pathway for

Answer 1

making limbs move

Question 2

what is the extrapyramidal pathway for

Answer 2

background work keeping us stable, balanced, fluid movement

Question 3

what is the general pathway of voluntary movement neurons

Answer 3

CNS sends axon down the brainstem to the spinal cord
sometimes uses an interneuron
lower motor neuron leaves the spinal cord and goes into limbs/muscles

Question 4

what makes a neuron in the pyramidal pathway

Answer 4

whether it goes through the medullary pyramids or not

Question 5

what does the alpha motor neuron to alpha motor neuron tract look like

Answer 5

decision - motor cortex - spinal cord - muscles

Question 6

what does the alpha motor neuron to alpha motor neuron tract look like

Answer 6

decision - motor cortex - spinal cord - muscles

Question 7

if you have to think about a movement what does the pathway look like

Answer 7

decision - pons - cerebellum - thalamus - motor cortex - spinal cord - muscles

Question 8

what is the pathway involved in making movement smooth

Answer 8

decision - basal ganglia

Question 9

what type of neurons are upper motor neurons

Answer 9

alpha motor neurons

Question 10

what type of neurons are lower motor neurons

Answer 10

alpha or gamma motor neurons

Question 11

what do gamma motor neurons do

Answer 11

monitor muscle spindle sensitivity and judge the baseline level of muscle tone (not overshooting or undershooting)

Question 12

what are the 2 tracts involved in motor control

Answer 12

lateral and anterior

Question 13

where do axons leave the cortex from

Answer 13

primary motor cortex, supplementary motor cortex, premotor cortex, sensory cortex (sometimes)

Question 14

why would neurons leave the sensory cortex

Answer 14

to amplify and upgrade the proprioception information

Question 15

what is the association cortex for

Answer 15

visually aided movement and to stop/start movement, suppress unwanted movements

Question 16

describe the movement of the neurons in the corticospinal tracts once leaving the cortex

Answer 16

cortex - corona radiata - posterior limb of internal capsule - midbrain - medulla - lateral/anterior corticospinal tract

Question 17

how many neurons are in the lateral corticospinal tract and where do they go

Answer 17

85%
go to lateral funiculus in ventral horn and then limb muscles

Question 18

how many neurons are in the anterior corticospinal tract and where do they go

Answer 18

15%
go to anterior funiculus in ventral horn and split into bilaterally paired neurons to go to midline muscles

Question 19

where is the damage if there is a lesion on upper motor neurons

Answer 19

on the opposite side of the body

Question 20

where is the damage if there is a lesion on lower motor neurons

Answer 20

on the same side of the body

Question 21

which place is the most common place where a stroke will cause quadriplegia

Answer 21

pons

Question 22

what is paresis

Answer 22

weakness but not full paralysis

Question 23

what is spinal shock

Answer 23

a period where nothing works

Question 24

what are the signs when there is upper motor neuron syndrome (stroke)

Answer 24

spastic paralysis, no muscle atrophy, hyperreflexia and clonus, hypertonia, positive babinski syndrome

Question 25

what causes spastic paralysis

Answer 25

increased activity of gamma motor neurons as they are uncontrolled by damaged alpha neurons

Question 26

why is there no muscle atrophy in UMN stroke

Answer 26

lower gamma neurons are fine and they nourish the muscle

Question 27

why does hyperreflexia happen

Answer 27

lower motor neurons randomly firing

Question 28

what causes hypertonia

Answer 28

gammas are trying to maintain readiness to move and it isnt regulated by alphas

Question 29

what is babinski sign

Answer 29

extensor plantar response

Question 30

what are the signs of lower motor neuron syndrome

Answer 30

flaccid paralysis, significant atrophy, visible twitching, spontaneous discharge of motor neurons, hyporeflexia, normal plantar response