Motor Systems - Lecture 6

Question 1

fxns

Answer 1

movement

posture and balance

communication

Question 2

what are the motor systems guided by

Answer 2

sensory systems

Question 3

hierarchal motor system architecture

Answer 3

cortex

cerebellum

brainstem

spinal cord

motoneurons

muscles

Question 4

upper motor neurons cell bodies

Answer 4

situated in the motor cortex

Question 5

upper motor neurons project

Answer 5

axons via the corticospinal tracts to the spinal cord

Question 6

where do UMN (upper motor neurons) synapse

Answer 6

anterior horn w/ lower motor neurons

Question 7

lower motor neurons (LMN) project

Answer 7

axons via the peripheral nerves

Question 8

what do the peripheral nerves do (LMN)

Answer 8

contact muscle fibers at the neuromuscular jxn

Question 9

damage to UMN

Answer 9

spasticity

hyperreflexia

damage above decussation

damage below decussation

Question 10

spasticity

Answer 10

excitation of extensors

Question 11

damage above decussation

Answer 11

contralateral effects

Question 12

damage below decussation

Answer 12

ipsilateral effects

Question 13

lower motor neurons

Answer 13

motor neurons connecting the brainstem and SC to muscle fibers

bringing the nerve impulses from the UMNs out to the muscles

Question 14

where does a LMN axon travel through

Answer 14

a foramen and terminates on an effector (muscle)

Question 15

motor unit

Answer 15

nerve-muscle fxnal unit

alpha motor neuron and all the muscle fibers it supplies

Question 16

number of muscle fibers per motor unit

Answer 16

can vary from a few (4-6) to hundreds (1200-1500)

Question 17

muscles that control fine movements

Answer 17

have small motor units

Question 18

large weight bearing muscles

Answer 18

have large motor units

Question 19

alpha motor neuron

Answer 19

final common path for all movement

Question 20

movement can be generated from

Answer 20

sensory signals in the muscles spindle like the stretch reflex

sensory signals from skin as in the pain withdrawal response

involuntary signals from the brainstem for posture, keeping us upright w/o conscious attention

signals from the brain for voluntary movement

Question 21

3 classes of movement

Answer 21

voluntary

reflexes

rhythmic motor patterns

Question 22

voluntary

Answer 22

complex actions –> reading, writing, playing piano

purposeful, goal oriented

learned –> improve w/ practice

Question 23

reflexes

Answer 23

involuntary, rapid, stereotyped
–> eyeblink, coughing, knee jerk

graded control by eliciting stimulus

Question 24

rhythmic motor patterns

Answer 24

combines voluntary and reflex acts
–> chewing, walking, running

initiation and termination voluntary

once initiated, repetitive and reflexive

Question 25

organization of motor control

Answer 25

hierarchal

parallel

Question 26

parallel

Answer 26

pathways active simultaneously

Question 27

hierarchical control of movement –> 3 levels of control

Answer 27

SC

brainstem

cortex

Question 28

hierarchical control of movement –> divisions of responsibility

Answer 28

higher levels

spinal cord

Question 29

higher levels

Answer 29

general commands

Question 30

SC

Answer 30

execution through skeletal muscles

Question 31

what does each level of the control of movement receive

Answer 31

sensory input

Question 32

hierarchical control –> SC

Answer 32

automatic and stereotyped responses

can fxn w/o brain

spinal interneurons

pathways converge on a motor neuron

Question 33

automatic and stereotyped responses –> hierarchical control –> SC

Answer 33

reflexes

rhythmic motor patterns

Question 34

spinal interneurons –> hierarchical control –> SC

Answer 34

same circuits as voluntary movement

Question 35

pathways converge on a motor unit –> hierarchical control –> SC

Answer 35

final common path

Question 36

hierarchical control –> brainstem

Answer 36

modulates neurons in SC to maintain balance and posture by interneurons and motor neurons

2 main parallel pathways

Question 37

2 main parallel pathways –> hierarchical control –> brainstem

Answer 37

medial

lateral

Question 38

medial –> hierarchical control –> brainstem

Answer 38

to ventromedial SC

postural/proximal muscles

Question 39

lateral –> hierarchical control –> brainstem

Answer 39

to dorsolateral SC

manipulative/distal muscles