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CRLS > Muscles and Tendons > Flashcards

Muscles and Tendons Flashcards

1
Q

Name the 3 kinds of muscle in the body

A
  • smooth (involutory) - visceral muscle
  • striated (voluntary) - skeletal muscle
  • cardiac - a type of striated muscle specific to the heart
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2
Q

Describe the structure of striated (skeletal) muscle

A
  • Muscles consist of many fascicles which are enclosed in epimysium (connective tissue)
  • Fascicles consist of many muscle fibres which are bound together in perimysium (connective tissue)
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3
Q

Describe muscle fibres structure

A
  • Formed by fusion of many myoblast cells - so have many nuclei
  • packed with contractile myofilaments in an interlocking arrangement - so nuclei also pushed to cell edge
  • many mitochondria for energy needs
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4
Q

Myofilaments - Describe what myosin does

A
  • binds to site on thin actin filament
  • myosin heads flex and pull actin
  • myosin heads release and bind to next site along
  • in this way myosin ratchets along actin
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5
Q

What is a sarcomere?

A
  • A sarcomere is the distance between the two z-disks
  • the sarcomere is the functional unit of muscle
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6
Q

What tissues make up the fascia?

A
  • the epimysium
  • the perimysium
  • endomysium
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7
Q

What does the perimysium cover?

A
  • the fascicle
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7
Q

what does the epimysium cover?

A
  • the muscle
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8
Q

What does the endomysium cover?

A
  • the muscle fibre
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8
Q

where do arteries enter muscle?

A
  • one or more may enter the muscle belly
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9
Q

What can the fascia do?

A
  • they can merge at the end of the muscle belly and continue as tendon or aponeurosis which attaches bones or other muscle bellies
  • muscles can also attach directly to bone (the periosteum) where collagen fibres continue as sharply fibres
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10
Q

What do muscle contractions do to veins and capillaries?

A
  • muscle contractions massage capillaries and veins but sustained mass muscle contractions may inhibit circulation
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11
Q

Describe the nerve in the muscle?

A
  • enters with the blood vessels and branches
  • multiple neurone types - motor, vasomotor, sensory
  • motor neurones generally from the ventral horn of spinal cord
  • motor neuron + fibres it innervates - motor unit
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12
Q

What is the H-zone?

A
  • just myosin on its own
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13
Q

What is the A-band?

A
  • full length of myosin including overlapping actin
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14
Q

What is the I-band?

A
  • just the actin filament on its own
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15
Q

What is the general pattern for muscles and tendons?

A
  • muscle is proximal
  • tenons are distal
  • proximal tendons tend to be shorter and fatter, distal tendons are longer
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16
Q

Describe the structure of a tendon?

A
  • composed of collagen fibre bundles in regular arrangement
  • arranged in primary, secondary and tertiary collagen fibre bundles
  • great tensile strength = transmit forces
  • elastic energy store, crimped collagen microanatomy
  • low metabolic needs - poor vascularisation but slow to heal
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17
Q

Roles of skeletal muscle?

A
  • joint movement
  • prevent joint movement - stabilisation
  • postural control
  • generating heat - shivering
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18
Q

Role of Cardiac Muscle?

A
  • Maintaining a cardiac rhythm
19
Q

Roles of smooth muscle?

A
  • continence
  • mastication
  • swallowing
  • digestion
  • birthing
  • vasodilation/ constriction
  • bronchodilation / constriction
  • pupil dilation / constriction
20
Q

Name skeletal muscles that DON’T connect bones to bones!

A
  • sphincters
  • circular muscles (orbicularis around the eye)
  • cutaneous muscles
  • muscles joining other muscles
21
Q

What force can muscle generate?

A
  • can only generate pull (tension) forces
22
Q

Muscle fibre contraction can occur as ..

A
  • muscle shortens (concentric contract)
  • muscle lengthens (eccentric contraction)
  • muscle stays the same length (isometric contraction)
23
Q

What can muscles act as?

A
  • motors
  • breaks
  • springs
  • stabilisers (sometimes called fixators or struts)
24
Q

What is an agonist?

A
  • An agonist or prime mover is responsible for a joint movement
25
Q

What is an antagonist?

A
  • an antagonist is capable of opposing that movement
26
Q

what are synergists?

A
  • other muscles that help or modify the action of an agonist without directly contributing to the action
  • for example, eliminating unwanted side effects
27
Q

what is a muscle origin?

A
  • most proximal or central
28
Q

what is a muscle insertion?

A
  • distal or peripheral
29
Q

Muscle design is closely linked with function what needs to be considered?

A
  • size
  • shape
  • number of bellies
  • tendinous origins or insertions
  • architecture
30
Q

What is force?

A
  • the push or pull on an object with mass, that causes it to change velocity
31
Q

what is work?

A
  • the application of force along a displacement
32
Q

Work equation:

A

force x change in distance

33
Q

What is power?

A
  • the rate of performing work
34
Q

Power equation:

A

change in work / change in time

35
Q

speed

A

change in distance /change in time

36
Q

What is muscle force proportional to?

A
  • muscle fibre cross- sectional area
37
Q

Describe parallel-fibred muscles

A
  • fibres run parallel to muscle line of action
  • little to no external tendon
  • sarcomeres are all in series in the fibres, so muscle can shorten more
  • fewer fibres in cross section so lower force
  • same potential for muscle work
  • can move joints through larger range of motion
  • potential to increase speed of joint movement
38
Q

Describe pennate-fibred muscles

A
  • shorter fibres attach at an angle to the muscles line of action
  • often insert via an external tendon to the skeleton
  • increased fibres in cross section so higher ability to generate force
  • some loss in force transmission along the kind of action
  • less muscle shortening overall (fewer fibres in series)
  • to generate the same force, less energy is needed (better force economy)
39
Q

Describe cardiac muscle

A
  • only found in the heart
  • striated
  • short branching
  • single central nucleus, many mitochondria
  • connected by intercalated discs
  • involuntary
40
Q

describe smooth muscle?

A
  • organ and vessel walls, iris
  • no striations
  • single nucleus
  • long contractions, low energy, low force
  • involuntary
41
Q

Describe tendons

A
  • dense regular connective tissue primarily composed of collagen
  • connect muscle to bone
42
Q

Describe ligaments

A
  • dense regular connective tissue primarily composed of collagen
  • connect bone to bone
43
Q

What are the different types of ligaments?

A
  • white ligaments, rich on collagen fibres, not very elastic, around the knee
  • yellow ligaments, lots of elastic fibres ( spine, pelvis, nuchal ligament
44
Q

What are the roles of tendons?

A
  • transmit force to skeleton (joins muscle to bone)
  • minimising distal limb mass
  • elastic energy storage
  • power amplification
  • energy absorption
45
Q

How can tendons be used in energy recovery?

A
  • can store and release elastic energy (up to 93%)
  • reduced mechanical work and cost of locomotion
46
Q

How can tendons be used in force economy?

A
  • long tendons allow for short muscle fibres
  • less energy cost developing muscle force
47
Q

How can tendons be used in power amplification?

A
  • muscles can contract slowly and forcefully to load tendon
  • stretched tendon can recoil faster that muscle can contract

CRLS (10 decks)

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