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Physio studies > Week 2 - muscle actions etc > Flashcards

Week 2 - muscle actions etc Flashcards

1
Q

7 functions of muscles

A
  • Produce movement
  • maintain postures + positions
  • stabilise joints
  • support + protect viscera (organs)
  • alter/control pressures in internal spaces eg. chest cavity
  • maintenance of temp
  • control entrances + exits to the body eg. swallowing
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2
Q

How do muscles do their job

A

By developing tension (pulling force at either or both ends of a linear object)

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3
Q

Describe a concentric contraction

A

When muscle tension force is greater than external load +/- gravity
- muscle shortens + joint movement is produced

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4
Q

Describe an eccentric contraction

A

When muscle tension force is less than external load but greater than gravity
- muscle lengthens + joint movement produced

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5
Q

Describe an isometric contraction

A

When muscle tension force is equal to external load +/- gravity
- Muscle length remains constant + no joint movement occurs

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6
Q

Describe an isokinetic contraction

A

When velocity of movement is constant as muscle shortens or lengthens

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7
Q

Differentiate b/t origin + insertion

A

Origin is the proximal muscle attachment whereas insertion is the distal muscle attachment

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8
Q

Describe an open kinetic chain in terms of origin + insertion

A

Origin is fixed + insertion moves towards origin

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9
Q

Describe a closed kinetic chain in terms of origin + insertion

A

Insertion is fixed + origin moves towards insertion

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10
Q

Describe the role of an agonist

A

Prime mover -
- can produce an isotonic or isometric contraction

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11
Q

Describe the role of an antagonist

A

Opposes action of agonist -
- must relax to allow movement to occur
- may act as a ‘brake’ at the end of rapid movement

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12
Q

Describe the role of an assistant agonist

A

Assists the agonist with the movement

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13
Q

Describe the role of the neutraliser

A

Limit unwanted movement by the agonist
eg. when walking upstairs rec fem wants to extend knee so hamstrings act as neutraliser to prevent this
- can also work in pairs as mutual neutralisers eg. flexor carpi ulnaris + flexor carpi radialis cancel out wrist deviation

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14
Q

Describe the role of stabilisers

A

Muscles that act in 1 segment so that a specific movement can occur at an adjacent joint
eg. rotator cuff ‘sucks’ ball of humerus into socket of scapula so its stabilised when shoulder abduction occurs

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15
Q

Describe the role of supporters

A

Similar to stabiliser but acts at a distance from moving joints to prevent movement by gravity
eg. abdominals during pushup

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16
Q

What is a force than can be used clinically to overcome gravity

A

Buoyancy

17
Q

What is mass

A

Quantity of the physical property of the matter

18
Q

What is weight

A

Object mass x acceleration due to gravity -> N

19
Q

Describe centre of mass

A

The right angle intersection b/t all 3 cardinal planes
- Mass is equal superiorly + inferiorly, anteriorly + posteriorly + left + right
- Same as COG when weight distributed evenly

20
Q

Describe centre of gravity

A

The point about which the body can balance perfectly against gravity
- can change or shift depending on orientation of body
- can lie inside or outside body

21
Q

Other factors influencing COG are

A

Age - COG becomes lower as move to adulthood
Sex - females have lower COG due to mass distribution

22
Q

Describe the line of gravity

A

Hypothetical line drawn through COG
- oriented downwards/ perpendicular to ground
- location coupled w/ COG

23
Q

Describe base of support

A

The total area beneath an object or surface
- includes all points of contact (and area b/t them) between object/person + surface

24
Q

Describe how to maintain stability

A

Line of gravity must remain inside base of support to remain upright

25
Q

Describe how to increase stability

A
  • Increase base of support
  • Increase points of contact w/ surface
  • Decrease COG
  • Aim to position LOG within BOS
26
Q

Define equilibrium

A

The state at which the sum of all forces acting upon a body or object are equal to zero -> body ‘at rest’
- LOG is within BOS

27
Q

Define stability

A

Resistance to being unbalanced (ie. LOG moving outside BOS)

28
Q

Define stable equilibrium (1st type)

A

An object or body whose COG will readily return to original position if acted upon by force

29
Q

Define unstable equilibrium (2nd type)

A

An object or body whose COG will readily accelerate away from original position when force is applied

30
Q

Define neutral equilibrium (3rd type)

A

An object or body whose COG is neither raised nor lowered when force is applied

31
Q

Explain the mobility-stability trade off

A
  • Stable state of eq. = LOG inside BOS
  • Metastable state of eq. = LOG moves towards boundaries/briefly beyond BOS -> necessary for walking/running
  • Unstable state of eq. = LOG outside BOS
32
Q

Define postural control + explain 2 functions of it

A

One of the body’s mechanisms for maintaining eq.
- magnitude varies w/ demands of the task
- vital for controlling body’s position in space + ensuring eye gaze is level

33
Q

State 3 roles of the motor system in postural control

A
  • Optimising skeletal alignments
  • Controlling postural tone (muscles produce minimal force over long time)
  • Muscle synergies (muscles working together to produce movement)
34
Q

Describe the 4 balance strategies (muscle synergies) for dealing with force

A

Ankle strategy - small force posteriorly
-> ankle moves into dorsi flexion/opposes w/ plantar flexion to move body back

Hip strategy - increase force
-> flexion of hips via trunk movement

Stepping - increased force w/ speed
-> changes BOS

Reaching - high force
-> need external assistance

35
Q

Describe the purpose + how to measure postural sway

A

Even when perceive selves as standing still -> moving
- antero-posterior sway + medial-lateral sway

Measures via centre of pressure on forcedecks

36
Q

List the factors affecting postural sway

A
  • Reduced sensory input eg. closing eyes
  • age
  • drugs
  • fatigue
  • neurological conditions

Physio studies (7 decks)

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