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Anatomy > Skeletal muscle > Flashcards

Skeletal muscle Flashcards

1
Q

What are the 2 main forms of muscle?

A

Striated

Non Striated

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2
Q

What types of muscle are striated?

A

Skeletal

Cardiac

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3
Q

What types of muscle are non striated?

A

Smooth

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4
Q

What is the mechanical efficacy of skeletal muscle?

A

20%

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5
Q

What are the main functions of skeletal muscle?

A

Movement
Posture
Stability of joints
Heat generation

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6
Q

What are the arrangements of muscle?

A 
Pennete
Convergent
Fusiform
Bipennete
Multipennate
Unipennate
Parallel
Circular
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7
Q

What is the Epimysium?

A

Outer connective tissue layer of muscle, continuous with the tendon

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8
Q

What is the Perimysium?

A

Encloses muscle fasicles

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9
Q

What are muscle fasicles?

A

Bundles of muscle fibres

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10
Q

What is the Endomysium?

A

Surrounds individual muscle fibres

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11
Q

What is fasciculation?

A

Involuntary twitching of fasicles. If common it can suggest neurological problems

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12
Q

What is a first class level system?

A

The load and force are either side of the fulcrum (Pivot) eg skull on the cervical vertebrae

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13
Q

Which is the most efficient type of level system?

A

First class level

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14
Q

What is a second class level system?

A

The load and force are on the same side of the fulcrum with the load closer to the fulcrum than the force. eg Lower leg and ankle

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15
Q

What is a third class level system?

A

The load and force are on the same side of the fulcrum, the load is further away than the force eg elbow

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16
Q

What are the main muscle groups?

A

Agonists, prime movers
Antagonists, oppose prime movers
Synergists, assist prime movers
Fixators, stabilise action of prime movers

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17
Q

What is compartment syndrome?

A

Trauma damages a blood vessel which may cause a bleed into a compartment causing a build up of pressure which presses on a nerve and causes pain.

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18
Q

What are the 2 types of muscle contraction?

A

Isotonic

Isometric

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19
Q

What is isotonic contraction?

A

Constant tension, variable muscle length. The muscle changes length and moves the load.

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20
Q

What are the 2 types of Isotonic contraction?

A

Concentric, muscle shortens eg lifting with the arm

Eccentric, muscle exerts a force while being extended eg walking downhill

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21
Q

What are the muscle fibre types?

A

Type I
Type IIa
Type IIb

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22
Q

What are type I muscle fibres?

A

Slow twitch fibres

Stain heavily - lots of mitochondria

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23
Q

What are type IIa muscle fibres?

A

Fast twitch or intermediate

Found particularly in sprinting

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24
Q

What are type IIb muscle fibres?

A

Fast twitch

Stain pale - little mitochondria

25
Q

What is proprioception?

A

Awareness of self and allows awareness of where limbs are in 3D space

26
Q

How does proprioception work?

A

Feedback control of muscle

Proprioceptors in muscles detect activity and feedsback via spinal cord

27
Q

What are proprioceptors?

A

Specialised muscle fibres encased in a capsule along with nerve endings.

28
Q

What is a motor unit?

A

A motor neuron and muscle fibre that innervates it

29
Q

How do muscles and neurones communicate?

A

With signalling molecules in both direction

30
Q

Why does the communication have to be constant?

A

Because if it wasn’t, the motor nerve and muscle would atrophy

31
Q

What are some examples of the communication molecules?

A

Neurotrophin 3
Cardiotrophin 1 (type of cytokine)
IGF1

32
Q

Why does muscle have a baseline tone at rest?

A

A baseline motor neuron activity

Retains tension in the muscle due to being an elastic tissue.

33
Q

What controls the muscle tone?

A

The motor cortex in the cerebrum in the brain

34
Q

What is Hypotonia?

A

Sudden loss of muscle tone/low level of muscle tone

35
Q

What can cause Hypotonia?

A

Injury to the motor cortex in the cerebrum
Lesions of the cerebellum
Lesions of sensory afferents from muscle spindles
Degeneration of the muscle body
Lesions of lower motornneurones

36
Q

What are the 2 types of summation?

A

Spatial

Temporal

37
Q

What is Spatial summation?

A

Increase force of contraction by increasing the number of motor units involved. (called recruitment)

38
Q

What is Temporal summation?

A

A series of action potentials in rapid succession causes muscle contraction. Doesn’t have enough time to relax so muscle contraction increases (Unfused tetanus)

39
Q

What is a fused tetanus?

A

When succession of action potentials causes constant contraction.

40
Q

What can mediate fused tetanus?

A

Toxin produced by Clostridium tetani

41
Q

What does an EMG do?

A

Measures the electrical activity in a muscle which is a compound effect of all the muscle fibres being acgtivated in a muscle.

42
Q

What can an EMG be used for?

A

Aiding diagnostics of certain types of motor neuron conditions

43
Q

How do EMGs work?

A

They can show an increase in the force of muscle contraction and an increase in recruitment.

44
Q

Calcium is removed to relax muscles, where does it go?

A

Back into the sarcoplasmic reticulum or bind to calmodulin

45
Q

What does muscle contraction require?

A

Calcium and ATP which are needed in constant supply

46
Q

What is the immediate store of ATP for a muscle?

A

Within the muscle, this is quickly depleted

47
Q

What is the second source of ATP for a muscle?

A

In Creatine phosphate. Lasts for about 15 seconds.

48
Q

How is Creatine phosphate a source of ATP?

A

Phosphorylates ADP to ATP

49
Q

What is the third source of ATP for muscle?

A

Anaerobic glycolysis.

50
Q

Why is anaerobic glycolysis not a favourable source of ATP?

A

Forms lactic acid which can cause lactic acidosis and cramps.

51
Q

What is the favourable third source of ATP for muscles?

A

Aerobic respiration.

52
Q

What is peripheral fatigue?

A

Effects peripheral muscle due to depletion of glycogen stores in the muscle.

53
Q

What can cause peripheral fatigue?

A

Interruption of blood flow to the muscles

54
Q

How does peripheral fatigue present itself?

A

Claudication (limping/interruption to walking)

Most common in the elderly

55
Q

What is intermittent claudication?

A

Where there is only pain on exercise, due to ischaemia.

56
Q

When can a state of continuous contraction occur?

A

When there is a depletion of ATP.

57
Q

How does a depletion of ATP cause continuous contraction?

A

The myosin heads are unable to detach from actin filaments as they need ATP

58
Q

What does continuous contraction cause?

A

Muscle stiffness

59
Q

What is Rigor Mortis?

A

Where ATP is depleted and not replenished after death so there is stiffness. Occurs after about 3 hours and can last 72 hours

Anatomy (45 decks)

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