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7303 Neuroanatomy > EXAM 2: Motor System 1 > Flashcards

EXAM 2: Motor System 1 Flashcards

1
Q

feedforward

A

the anticipatory use of sensory information to prepare for movement

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2
Q

feedback

A

the use of sensory information during or after movement to make corrections either to ongoing movement or to future movements

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3
Q

Automatic movements require continuous integration of:

A
  • visual
  • somatosensory
  • vestibular info
  • motor processing
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4
Q

In the absence of vision, reaching depends on this to locate objects

A
  • somatosensation

- proprioception

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5
Q

What disrupts positioning of limbs in individuals with complete deafferentation?

A

Loss of somatosensation

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6
Q

What does neural activity begin with?

A

with a decision made in the anterior part of the frontal lobe

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7
Q

follow the path of neural activity

A
  • frontal lobe
  • motor planning areas activated
  • control circuits activated (in UMN tracts)
  • UMN tracts deliver signals to interneurons and LMNs
  • LMNs transmit signals to skeletal muscles
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8
Q

What are control circuits?

A

consist of cerebellum and basal ganglia

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9
Q

What do control circuits do?

A
  • regulate activity in UMN tracts

- activation results in excitation or inhibition of motor neurons

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10
Q

UMN tracts deliver signals to

A
  • interneurons

- LMNs

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11
Q

classification of UMN tracts

A
  • postural/gross movement tracts
  • fine movement tracts
  • nonspecific UMNs
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12
Q

postural/gross movement tracts control:

A

automatic skeletal muscle activity

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13
Q

fine movement tracts control:

A

fractionated movements of limbs and face

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14
Q

nonspecific UMNs control:

A

all motor neurons

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15
Q

What do LMNs do?

A
  • transmit signals directly to skeletal muscles

- elicit contraction of muscle fibers that move the upper limbs and fingers

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16
Q

How is voluntary movement controlled?

A

top down

  • brain
  • spinal cord
  • muscle
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17
Q

properties of skeletal muscle

A
  • excitable
  • contractile
  • extensile
  • elastic
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18
Q

t-tubules

A
  • transverse tubules

- projections of muscle cell membranes that extend into the muscle

19
Q

sarcoplasmic reticulum

A

series of storage sacs for Ca2+ ions

20
Q

myofibrils

A

individual muscle fibers

21
Q

sarcomeres

A

arrangement of proteins in a myofibril

22
Q

two protein types in sarcomeres

A
  • structural

- contractile

23
Q

structural proteins of sarcomeres

A
  • Z line
  • M line
  • titin
24
Q

M line

A

anchors fibers in center of sarcomere

25
Q

titin

A
  • connects Z line with m line
  • maintains position of myosin relative to actin
  • prevents sarcomere from being pulled apart
26
Q

contractile proteins of sarcomeres

A
  • myosin
  • actin
  • tropomyosin
  • troponin
27
Q

contraction

A
  • Produced when active slides relative to myosin

- Repeated attachment, swiveling, and detachment of myosin heads produce contraction of the muscle

28
Q

What do muscles behave like?

A

springs

29
Q

______ springs generate more resistance to stretch than the same spring when it is _______

A
  • stretched

- shortened

30
Q

What determines total resistance to muscle stretch?

A
  • active contraction
  • titin
  • weak actin-myosin bonds
31
Q

muscle tone

A

resistance to stretch in a resting muscle

32
Q

How is muscle tone assessed?

A

assessed clinically using PROM

33
Q

When tone is normal, resistance to passive stretch is

A

minimal

34
Q

Normal resting muscle tone provided by

A
  • titin

- weak actin-myosin bonds

35
Q

weak actin-myosin bonds

A
  • attached, but myosin heads don’t swivel

- no muscle contraction, but there is resistance

36
Q

What happens to actin-myosin bonds if muscle is immobile for a prolonged period?

A
  • bonds continually form

- broken by stretching the muscle

37
Q

stretch velocity and actin-myosin bonds

A

The faster the stretch, the greater the resistance

38
Q

What happens when healthy innervated muscle is continuously immobilized in a shortened position for a prolonged period?

A

sarcomeres disappear from the ends of myofibrils

39
Q

Why do sarcomeres get lost when immobilized in a shortened position?

A

Loss of sarcomeres is a structural adaptation to the shortened position so the muscle generates optimal force at the new resting length

40
Q

What happens when a structurally shortened muscle is stretched?

A

it quickly reaches the limits of its elasticity and is resistant to stretching

41
Q

What happens if a muscle is immobilized in a lengthened position?

A

the muscle adds new sarcomeres

42
Q

cocontraction

A

simultaneous contraction of antagonist muscles

43
Q

What does cocontraction do?

A
  • stabilizes joints
  • UE: enables precise movements
  • LE: allows individual to stand on an unstable surface

7303 Neuroanatomy (69 decks)

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