Motor System - Overview & Cortical Influence

Question 1

Motor activity is generated and controlled through complex interactions of

Answer 1

• Brainstem tracts
• Frontal lobe, particularly primary motor cortex
• Cerebellum
• Basal ganglia
• Thalamus

Question 2

complex pattern of muscle activation must be

Answer 2

planned and generated

Question 3

Feedback occurs at all levels, but is primarily processed by

Answer 3

cerebellum

Question 4

Peripheral motor control begins with?

Answer 4

the innervation of muscle by alpha motor neurons

Question 5

alpha motor neuron innervates

Answer 5

one or more muscle fibers

Question 6

size of a motor unit depends on what?

Answer 6

the number of muscle fibers it innervates

Question 7

1 single motor neuron will innervate what?

Answer 7

1 fiber

Question 8

Smaller motor neurons with lower thresholds (and lower contraction force) are what?

Answer 8

recruited first

Question 9

larger motor neurons have what?

Answer 9

higher thresholds & generate more forces

Question 10

Type I / S is what?

Answer 10

slow oxidative (SO)

Question 11

• Small force
• slow twitch
• fatigue resistant
• Oxidative
• innervated by small diameter slow conducting axons

Answer 11

Type I / S = slow oxidative (SO)

Question 12

postural control axons would be innervated by what kind of muscle fiber?

Answer 12

Type I / S = slow oxidative (SO)

Question 12

Metabolic pathways are oxidative and anaerobic glycolytic would be innervated by what kind of muscle fiber?

Answer 12

Type IIa / FR = fast oxidative glycolytic (FOG)

Question 13

gastrocnemius would be innervated by what kind of muscle fiber?

Answer 13

Type IIb / FF = fast glycolytic (FG)

Question 14

• Intermediate force
• relatively fast contractile time
• generates larger tension
• intermediate to slow rate of fatigue
• innervated by large diameter rapidly conducting axons

Answer 14

Type IIa / FR = fast oxidative glycolytic (FOG)

Question 15

Type IIa / FR is what?

Answer 15

fast oxidative glycolytic (FOG)

Question 16

• rapidly contracting fibers
• rapidly fatigue
• white muscle
• contain large stores of glycogen
• high contraction force
• recruited later in the contraction pattern to recruit - - large forces
• large fibers supplied by large diameter axons

Answer 16

Type IIb / FF = fast glycolytic (FG)

Question 17

Type IIb / FF is what?

Answer 17

fast glycolytic (FG)

Question 18

primary peripheral sensory organs within a muscle to detect the speed and extent of muscle stretch

Answer 18

Muscle spindles or intrafusal muscles

Question 19

a muscle contracts in direct response to its stretch

Answer 19

myotatic reflex

Question 20

neuron used to adjust the tension or sensitivity of the muscle spindle as the muscle shortens

Answer 20

Gamma motor neuron

Question 21

what type of muscle is important in the control of muscle tone (tension) in postural muscles mostly at an unconscious level

Answer 21

Gamma motor neuron

Question 22

result in abnormal tone is a result in damage to what?

Answer 22

Gamma motor neuron

Question 23

alpha-gamma coactivation

Answer 23

contraction of extrafusal muscle (on the outside [actually the muscle) which lengthens and contracts) while the intrafusal muscle (inside where the spindles are - length & speed of the stretch during actual contraction) or coactivation of alpha motor neuron and gamma motor neurons for accurate monitoring during motor movement

Question 24

actual force of tension and contraction

Answer 24

Golgi Tendon Organ

Question 25

sensory fiber supplies what

Answer 25

Golgi Tendon Organ

Question 26

inhibit the contraction of the agonist and allowing the contraction of the antagonist

Answer 26

Autogenic inhibition

Question 27

what receptors plays a role in the control of muscle activity both directly (pain influences) and indirectly through central mechanisms

Answer 27

joint and cutaneous receptors

Question 28

what receptors plays a large role in muscle activity under certain circumstances

Answer 28

Joint receptors (in motor control)

Question 29

systems are typically under descending system inhibition and may only be released under certain circumstance

Answer 29

flexor reflex afferents

Question 30

under central inhibition, allowing the plantar flexion response to predominate under normal conditions of innervation

Answer 30

Babinski Reflex

Question 31

create patterns of sequential activity when activated

Answer 31

Central pattern generators

Question 32

two major divisions of motor cortex involved in somatic motor function

Answer 32

1. Primary motor cortex
2. Supplementary motor cortex (and premotor cortex)

Question 33

• controlling the face and tongue are near the lateral fissure and those
• controlling the legs are near or over the midline
• Parallel processing: considerable variation in motor deficits with lesions of cerebral cortex and the tracts from these areas along with potential mechanisms for recovery
• activated during random movement
• tracts exert their strongest influence over extensor musculature in the proximal body

Answer 33

Primary motor cortex

Question 34

• contribute to eye movements (frontal eye fields)
• activated by movements that are planned and rehearsed mentally without actually making a movement

Answer 34

Supplementary motor cortex (and premotor cortex)

Question 35

• control cranial nerve motor functions include eye movements (CN III, IV,& VI)
• control muscles associated with the head (V, VII, IX, X, XI, XII)

Answer 35

Corticonuclear Tract

Question 36

what percent of axons don’t cross the midline or terminate bilaterally

Answer 36

10 to 15%