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Musculoskeletal System > Session 2 - Muscle Structure, Morphology and Mechanics > Flashcards

Session 2 - Muscle Structure, Morphology and Mechanics Flashcards

0
Q

List the arrangement of muscles from bone to myofilaments

A

-Bone, tendon, muscle, fascicle, fibre. myofibril, myofilaments

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1
Q

What are the possible arrangements of skeletal muscle?

A
  • Circular
  • Convergent
  • Multipennate
  • bipennate
  • Unipennate
  • Parallel
  • Fusiform
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2
Q

What are the main functions of skeletal muscle?

A
  • Movement
  • Posture
  • Joint stability
  • Heat generation
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3
Q

What is fasciculation?

A

-Muscle twitch

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4
Q

What is the agonist muscle during a movement?

A

-The prime mover which exerts a force or effect (main muscle responsible for movement)

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5
Q

What is the antagonist during a movement?

A

-The muscle which opposes the prime mover, allowing control of a movement

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6
Q

What does a synergist muscle do in a movement?

A

-Assists prime mover by neutralising extra motion, eg sideways motion

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7
Q

What is the function of a fixator during a movement?

A

-A muscle which stabilises the action of the prime mover eg fixes a non-moving joint when prime mover acts over two joints

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8
Q

What is a 1st class lever?

A

-The load is on the opposite side to the muscle, central to the fulcrum eg skull

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9
Q

What is a second class level?

A

-The load is on the same side to the muscle but close to the fulcrum

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10
Q

What is a third class lever?

A

-The load is on the same side of the muscle far away from the fulcrum

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11
Q

What is compartment syndrome?

A
  • Compartments of limbs surrounded by non-expandable fascia
  • Anything which causes a large increase in pressure in the compartment can lead to compression of the blood supply and nerves, possible leading to necrosis of compartment
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12
Q

What is isotonic contraction?

A

-Contraction of the muscle resulting in constant muscle tension and varying muscle length

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13
Q

What is the difference between concentric and eccentric isotonic muscle contraction?

A
  • Concentric muscle shortens in length

- Eccentric muscle extends in length

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14
Q

What is delayed-onset muscle soreness, what is a common cause?

A
  • Muscle soreness wich becomes symtomatic a few days after the causing factor
  • Walking down hill
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15
Q

What is isometric contraction?

A

-Contraction of muscle where muscle stays the same length but there is varying tension eg hand grip

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16
Q

Why can isometric contraction be important in the elderly or those with hypertension?

A

-There is a small muscle mass involved in isometric contraction, however it has a large effect on blood pressure

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17
Q

Describe type I muscle fibres

A

-Aerobic, red with rich capillaries, many mitochondria and fatigue resistant, slow oxidative with endurance

18
Q

Describe type IIa muscle fibres

A

-Aerobic, red/pink with rich capillary supply, many mitochondria and moderately fatigue resistant, fast oxidative,

19
Q

Describe type IIb muscle fibres

A

-Anaerobic, white with poor capillary supply, few mitochondria and fatigue rapidly, short intense movements

20
Q

What is proprioception?

A

-Awareness of self

21
Q

How does proprioception work?

A
  • Feedback control by proprioceptors

- Proprioreceptor muscle spindles send messages about tension and stretch being exerted on the muscle to the brain

22
Q

What is a motor unit?

A

-A motor neurone and the muscle fibres it innervates (ie each axon innervates several muscle fibres

23
Q

How is the number of muscle fibres per axon determined?

A

-Depends on how fine of control needed for the movement

24
Q

What can atrophy of a nerve/muscle cause on its corresponding nerve/muscle? Why?

A

-Atorphy due lack of chemical signals, eg neurotrophins/cytokines

25
Q

What is muscle tone?

A

-The continuous and passive part-contraction of muscles

26
Q

What determines baseline muscle tone?

A

-Baseline motor neurone activity and muscle elasticity

27
Q

What controls tone which occurs above baseline?

A
  • Motor control centres in the brain
  • Afferent muscle fibre signals
  • Negative feedback from muscle spindles
28
Q

What are four possible causes of hypotonia?

A
  • Lesions of sensory afferents
  • Cerebral/spinal shock
  • Primary degeneration of muscles
  • Lesion of lower motor neurones
29
Q

What is a synaptic bouton?

A

-Flattened terminal of axon at NMJ used to increase SA

30
Q

How many molecules of Ach bind to NachR?

A

-2 ach -> 2 a-subunits

31
Q

What is a depolarising blockade anaesthetic?

A

-An anaesthetic which mimics ach, which in excess causes an initial depolarisation followed by a block of the NMJ and ultimately muscle relaxation

32
Q

What is a non-depolarising anaesthetic?

A

-One which blocks the nicotinic receptors

33
Q

What is recruitment?

A

-The more neurones activated, the more muscle fibres are recruited to develop more force

34
Q

What is unfused tetanus?

A

-A series of action potentials causes a series of twitches together

35
Q

What is fused tetanus?

A

-Action potentials become more frequent and muscle doesnt get time to relax so contraction becomes continuous

36
Q

What is tetanus?

A

-Clostridium tetani’s exotoxin causes muscle spasms and rigidity by interfering with feedback control of muscle tension

37
Q

What is an electromyography?

A

-A diagnostic tool where electrodes are placed above or in muscles to measure the electrical activity

NB:recruitment of muscle fibres should match the force of contraction

38
Q

How does relaxation of muscle occur?

A
  • Ca2+ is pumped back into the sarcoplasmic reticulum by SERCA
  • Some calcium binds to calmodulin
39
Q

Why is ATP needed in continual muscle contraction?

A

-In order to detach myosin heads from actin filaments

40
Q

Where do muscles get their ATP from?

A
  • Oxidative phosphorylation
  • Glycolysis
  • Creatine phosphate
  • Anaerobic glycolysis
41
Q

What is a contracture?

A

-State of continuous contraction

42
Q

Why does contracture occur when ATP is depleted?

A

-Myosin heads remain bound to actin filaments so muscle stays contracted

Musculoskeletal System (34 decks)

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