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Semester 2 FS Exam 2 > Muscle > Flashcards

Muscle Flashcards

1
Q

Function of muscles

A
  1. Almost always cross at least one joint
  2. When a muscle contracts, it produces force btw two sides of joint
  3. Force generally acts at a distance from the joint center
  4. Produces a moment of force about the joint center
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2
Q

Single joint muscles

A

Only produce movement at a single joint

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3
Q

Multiple joint muscles

A

May move two or more joints in the same direction
May move one joint while others are static
May move joints in oppostire directions

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4
Q

Mono-articular muscles are primarily used to

A

generate positive work (concentric)

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5
Q

Bi-articular muscles are used for

A

energy transfer btw joints

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6
Q

Pennation

A

orientation of the muscle fibers with respect to muscle attachments
Pennation angle impacts how much (how many fibers) you can fit into your real estate
Fiber packing - greater in pennate

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7
Q

The more pennation…

A

the lower the velocity

the more fibers though –> force –> strength

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8
Q

The less pennation

A

the lower the ability to produce force

But the more parallel –> length –> velocity

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9
Q

Parallel

A

Change length a lot

Velocity

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10
Q

Higher pennation angle

A

the less the cosine is
higher pennation angle with shortening
Lower pennation angle with relax (lengthening)

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11
Q

Velocity muscles have a pennation angle of

A

0

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12
Q

FL/ML Ratio

A

Fiber length/Muscle length
Low number = force = more pennation
High number = velocity = more parallel

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13
Q

Ratio tells you something, but also need to know

A

CSA
Larger CSA –> shorter length –> strong
Long length –> small CSA –> velocity

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14
Q

Def of msucle mechanics

A

The study of external mechanical variables given the internal contractile state of muscles
The study of length effects, velocity efects, power generation, and force generation in a muscle

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15
Q

Contraction mechanics

A

the action responsible for the contraction of a muscle occurs within a sarcomere

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16
Q

The greater the number of cross bridges attached to the actin filaments –>

A

the larger the contraction force

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17
Q

sliding filaments

A

Actin and myosin

Force is generated by cross bridges

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18
Q

myosin

A

thick

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19
Q

actin

A

thin

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20
Q

A single stimulus from the motor neuron results in

A

a twitch response of the fiber

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21
Q

With inc frequency of stimulus

A

there will be tension in the fiber when the next stimulus arrives
If freq of stimuli is wide enough, a tetanic response of fibers reults

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22
Q

Tetanic response

A

Keep stimulating and then you have them building up and doesnt ever decay back so then you have tetanic response - max force that it can produce

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23
Q

Force we experience at attachment of a muscle

A

a summation of how many motor units are active and how well they stimulate

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24
Q

Concentric muscle contraction

A

shortening contraction
least force developed when maximally stimulated
Produces force while becoming shorter

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25
Q

Isometric muscle contraction

A

Joint angle remains constant

intermediate force when maximally stimulated

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26
Q

Eccentric muscle contraction

A

lengthening contraction

Greatest force developed when maximally stimulated

27
Q

Isotonic

A

Uniform tension in muscle (amount of force/tension remains the same)
Not really found in the real world
EMG electrode is one of only real ways

28
Q

Isokinetic

A

Constant angular velocity
Produced during use of isokinetic hynamometer
Also not in real world - cant produce this only with the use of machines

29
Q

Agonist

A

muscle that produces desired movement - can have many

Have 1 prime mover - the main muscle with largest CSA (geom is better with respect to ma))

30
Q

Antagonist

A

Any muscle with opposing action

31
Q

Co-contraction

A

simultaneous contraction of agonist and antagonist

Happens pretty often - stabilizing translatory forces of both muscles going towards the joint to help give stability

32
Q

Synergist

A

A muscle which helps the agonist in some way

Working at the same time in a similar way

33
Q

Ways in which a synergist can act

A

Similar action to agonist
Stabilizes neighboring joint
Prevents unwanted actions by agonist

34
Q

Doing shoulder adduction with resistance cables

A 
Action = shoulder adduction
Prime mover = lat
Agonist = teres major
Stabilizor = rotator cuff
 Neutralizer (stabi) = rhomboid
Antagonist = deltoid
35
Q

Tonic muscles

A

stablizing
high proportion of slow twitch (type I) fibers
Endure long term exercise
Used primarily to maintain posture

36
Q

Phasic muscles

A

mobility
High proportion of fast - twitch (type IIa and IIb) fibers
Used primarily for short powerful actions

37
Q

At resting length - CB formation
Shorter than resting
Longer than resting

A

At resting can get quite a bit
Shorter than resting not as much
Longer than resting maybe inc a little but then decays

38
Q

Passive (not contractng) muslce acts like

A

a spring
bx of a tendon
Has to be stretched in order to give us force

39
Q

musculotendinous unit ability to produce force

A

Working range = 70-100% of resting length

We get to 85-120 is able to produce max force

40
Q

Active insufficiency

A

muscle is too short to produce force

wrist in flexion - finger flexors are to short

41
Q

Passive insufficiency

A

muscle is too long to produce force

wrist in flexion - finger extensors are too long

42
Q

Single joint muscles

A

usually operate over their most efficient length

43
Q

Multiple joint muscles

A

may become too short to produce force (active insuff)

OR may become tightly stretched - too long to produce force (passive)

44
Q

Ex of active insufficiency

A

Hamstrings with knee flexed and hip extended

Finger flexors with wrist flexed

45
Q

Ex passive insufficiency

A

hamstrings with knee extended and hip flexed

Finger extensors with wrist flexed

46
Q

Hamstring - lifting foot up behind butt in standing position

A

active

position of knee and hip - too short

47
Q

Hamstring - Rising from a squat

A

just right

when rising - shorter at hip and longer at knee so overall is the same - at working range

48
Q

Hamstring - bending down to touch toes

A

passive

49
Q

Backwards straight leg raise (prone positon)

A

within working range because not that much rang of motion?

50
Q

For a concentric contraction

A

slower contractions can produce more force

51
Q

For an eccentric contraction

A

faster contractions can produce more force

52
Q

For an isometric contraction

A

somewhere in btw

53
Q

Isometric contravtion - velocity =

A

zero

54
Q

Concentric - velocity and peak force graph

A

Vel inc positively

Becoming shorter faster and faster

55
Q

Eccentric - velocity and peak force graph

A

Vel inc negatively

Becoming longer faster and faster

56
Q

Factors affecting maximal joint torque

A
  1. Muscle CSA
  2. Position of joint
  3. Direction of contraction
  4. Speed of contraction
57
Q

Muscle CSA

A

Bumber of fibers will impact the force –> impact torque

58
Q

POsition of joint

A 
muscle length (length/tension relationship)
Bone oreintation (moment arm) 
Both impact torque
59
Q

Direction of contraction

A

eccentric –> isometric –> concentric

60
Q

Speed of contraction

A

slow > fast (conc)

fast > slow (ecc)

61
Q

Atrophy

A

Weakening and shrinking of a muscle

Maybe caused by disuse - immob or loss of neutral stimulation

62
Q

Hypertrophy

A

Although most muscle hypertrophy resutls from inc in size of muscle fibers (hypertrophy) some also occurs from number of muscle fibers (hyperplasia)

63
Q

Fiber adaptations

A

Evidence indicated that one fiber type might actually be covnerted to another type as a result of cross innervation or chronic stimulation

64
Q

Atrophy - training stopped

A

Atrophy bvegins quickly is training is stopped but training can be reduced without resulting in atrophy or loss of strength

Semester 2 FS Exam 2 (6 decks)

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