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Semester 2 FS Exam 2 > Muscle > Flashcards

Muscle Flashcards

(64 cards)

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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
Isometric muscle contraction
Joint angle remains constant | intermediate force when maximally stimulated
26
Eccentric muscle contraction
lengthening contraction | Greatest force developed when maximally stimulated
27
Isotonic
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
Isokinetic
Constant angular velocity Produced during use of isokinetic hynamometer Also not in real world - cant produce this only with the use of machines
29
Agonist
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
Antagonist
Any muscle with opposing action
31
Co-contraction
simultaneous contraction of agonist and antagonist | Happens pretty often - stabilizing translatory forces of both muscles going towards the joint to help give stability
32
Synergist
A muscle which helps the agonist in some way | Working at the same time in a similar way
33
Ways in which a synergist can act
Similar action to agonist Stabilizes neighboring joint Prevents unwanted actions by agonist
34
Doing shoulder adduction with resistance cables
``` Action = shoulder adduction Prime mover = lat Agonist = teres major Stabilizor = rotator cuff Neutralizer (stabi) = rhomboid Antagonist = deltoid ```
35
Tonic muscles
stablizing high proportion of slow twitch (type I) fibers Endure long term exercise Used primarily to maintain posture
36
Phasic muscles
mobility High proportion of fast - twitch (type IIa and IIb) fibers Used primarily for short powerful actions
37
At resting length - CB formation Shorter than resting Longer than resting
At resting can get quite a bit Shorter than resting not as much Longer than resting maybe inc a little but then decays
38
Passive (not contractng) muslce acts like
a spring bx of a tendon Has to be stretched in order to give us force
39
musculotendinous unit ability to produce force
Working range = 70-100% of resting length | We get to 85-120 is able to produce max force
40
Active insufficiency
muscle is too short to produce force | wrist in flexion - finger flexors are to short
41
Passive insufficiency
muscle is too long to produce force | wrist in flexion - finger extensors are too long
42
Single joint muscles
usually operate over their most efficient length
43
Multiple joint muscles
may become too short to produce force (active insuff) | OR may become tightly stretched - too long to produce force (passive)
44
Ex of active insufficiency
Hamstrings with knee flexed and hip extended | Finger flexors with wrist flexed
45
Ex passive insufficiency
hamstrings with knee extended and hip flexed | Finger extensors with wrist flexed
46
Hamstring - lifting foot up behind butt in standing position
active | position of knee and hip - too short
47
Hamstring - Rising from a squat
just right | when rising - shorter at hip and longer at knee so overall is the same - at working range
48
Hamstring - bending down to touch toes
passive
49
Backwards straight leg raise (prone positon)
within working range because not that much rang of motion?
50
For a concentric contraction
slower contractions can produce more force
51
For an eccentric contraction
faster contractions can produce more force
52
For an isometric contraction
somewhere in btw
53
Isometric contravtion - velocity =
zero
54
Concentric - velocity and peak force graph
Vel inc positively | Becoming shorter faster and faster
55
Eccentric - velocity and peak force graph
Vel inc negatively | Becoming longer faster and faster
56
Factors affecting maximal joint torque
1. Muscle CSA 2. Position of joint 3. Direction of contraction 4. Speed of contraction
57
Muscle CSA
Bumber of fibers will impact the force --> impact torque
58
POsition of joint
``` muscle length (length/tension relationship) Bone oreintation (moment arm) Both impact torque ```
59
Direction of contraction
eccentric --> isometric --> concentric
60
Speed of contraction
slow > fast (conc) | fast > slow (ecc)
61
Atrophy
Weakening and shrinking of a muscle | Maybe caused by disuse - immob or loss of neutral stimulation
62
Hypertrophy
Although most muscle hypertrophy resutls from inc in size of muscle fibers (hypertrophy) some also occurs from number of muscle fibers (hyperplasia)
63
Fiber adaptations
Evidence indicated that one fiber type might actually be covnerted to another type as a result of cross innervation or chronic stimulation
64
Atrophy - training stopped
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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