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Semester 2 - MSK > Session 2 - Skeletal muscle > Flashcards

Session 2 - Skeletal muscle Flashcards

1
Q

Give four functions of skeletal muscle

A

Movement
Posture
Stability of joints
Heat generation

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2
Q

Why is a mechanical effiency of 20% useful for skeletal muscle?

A

Large amount of energy lost as heat e.g. shivering

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3
Q

Give 7 types of skeletal muscle

A 
Circular
Convergent
Parallel
Unipennate
Multipennate
Fusiform
Bipennate
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4
Q

What is a first class lever muscle?

A

Force —- Fulcrum — Load

Load and force on opposing sides

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5
Q

Give an example of a first class lever muscle

A

The muscles in the posterior region of the neck attached to the skull

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6
Q

What is a second class lever?

A

Force – Load – Fulcrum

Force and load on same side of fulcrum, with load between force and fulcrum

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7
Q

Give an example of a second class lever

A

The muscles in the back of the calf flex the foot by exerting force on the calcaneus

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8
Q

What is a third class lever

A

Fulcrum – Force – Load

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9
Q

Give an example of a third class lever

A

Biceps

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10
Q

What is the most common type of lever? How efficient are they?

A

Third class, the least efficient

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11
Q

What is an agonist?

A

Prime movers (main muscles responsible for a particular movement

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12
Q

What is an antagonist?

A

Oppose prime movers (agonists)

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13
Q

What are synergists?

A

Assist prime movers (neutralise extra motion)

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14
Q

What are fixators?

A

Stabilize action of prime movers e.g. fixes non-moving joint when prime mover acting over two joints

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15
Q

What is a compartment?

A

Limbs are divided into comparments, which are lined and defined by fascia.

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16
Q

What is COMPARTMENT SYNDROME?

A

Trauma in a compartment can cause internal bleeding, which could exert pressure on blood vessels and nerves in the compartment. This can give rise to a variety of symptoms and is called compartment sydrome.

17
Q

What is an isotonic contraction? What are the two types?

A

Constant tension, variable muscle length

Concentric and eccentric

18
Q

What is a concentric isotonic contraction?

A

Muscle shortens e.g. lifting a load with the arm

19
Q

What is an eccentric contraction?

A

The muscle exerts a force while being extended

20
Q

What is isometric contraction?

A

Constant length of muscle, variable tension e.g. hand grip

21
Q

What are three types of muscle fibre?

A

Type 1, Type IIa and Type IIb

22
Q

What is type I?

A

High oxidative capacity and are resistant to fatigue. Maintain contractions over long periods of time and are very important in postural muscles.

23
Q

What is type IIb?

A

Mostly obtain energy via glycolysis and rapidly fatigue

24
Q

What is proprioception?

A

touches nose

Feedback control of movement

25
Q

How is proprioception determined

A

By special nerve endings known as proprioceptors and muscle spindles in muscles, which sense the degree of stretch and tension in the muscle.

26
Q

Why are muscle spindles clinically useful?

A

Give rise to some reflexes in the body which can be tested

27
Q

What is a motor unit?

A

A motor neurone and the muscle fibres that it innervates

28
Q

How many muscle fibres per motor neurone?

A

Anywhere between 2 and 2000 muscle fibres, depending on degree of fine control required

29
Q

What is cross-talk?

A

Signalling molecules communicate between nerve and muscle. If one atrophys, so does the other

30
Q

How do muscles increase force generated?

A

More motor units activated, via process known as recruitment. Termed spacial summation.

31
Q

What aids in recruitment?

A

Motor neurones, feedback from muscle spindles, joint receptors and golgi tendon organs

32
Q

What is temporal summation?

A

Increased frequency of action potentials causes summation and tetanus

33
Q

What occurs in tetanus?

A

Toxin from bacterium clostridium tetani blocks inhibitors motor feedback control which leads to unopposed muscle contraction

34
Q

What is EMG?

A

Method of measuring electrical activity in muscle, via method known as electromyography

35
Q

How do muscle cells relax?

A

Ca 2+ pumped back into the SR via Ca 2+ pumps

Some Ca2+ binds to a protein known as calmodulin

Semester 2 - MSK (36 decks)

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