Tissues + Structures - Muscles Flashcards

1
Q

What are the types of muscles?

A
  1. Skeletal.
  2. Cardiac.
  3. Visceral (smooth).
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2
Q

What are the histological classifications of muscle?

A
  1. Striated (skeletal, cardiac).
  2. Non-striated (visceral).
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3
Q

What is the difference between muscle cell and fibre?

A

They are the same thing.

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4
Q

Describe the nuclei situation of the three types of muscle?

A
  1. Smooth - single nucleus.
  2. Cardiac - single nucleus.
  3. Skeletal - multiple nuclei.
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5
Q

What does smooth muscle consist of?

A

Narrow spindle shaped cells that lay parallel.

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6
Q

Describe smooth muscle in tubes that undergo peristalsis?

A

Arranged in longitudinal and circular fashion.

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7
Q

Describe smooth muscle fibres in viscera that undergo contraction without peristalsis (bladder and uterus)?

A

Fibres arranged in whorls and spirals.

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8
Q

What are gap junction?

A

These are nexuses that allow for contractile impulses to be transmitted from one smooth muscle cell to the next adjacent cell.

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9
Q

What innervates smooth muscle?

A

Autonomic nervous system. However, due to gap junctions many smooth fibres do not receive nerve fibres.

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10
Q

What does cardiac muscle consist of?

A

Broader short cells that branch.

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11
Q

How is cardiac muscle cells arranged?

A

Whorls and spirals.

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12
Q

How doe the cells connect with each other?

A

Interdigitations with one another, these help to increase the surface area for impulse conduction.

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13
Q

How does each chamber of the heart empty blood?

A

By mass contraction - no peristalsis involved.

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14
Q

What innervates cardiac muscle?

A

Autonomic nervous system.

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15
Q

What does skeletal muscle consist of?

A

Non-branching fibres bound together by loose aerolar tissue (containing macrophages and fibroblasts).

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16
Q

How is connective tissue made in skeletal muscle?

A

Condensed to create a epimysium.

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17
Q

Why is the epimysium important?

A

Helps to prevent the spread of fluid such as pus.

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18
Q

What are the types of skeletal muscle?

A
  1. Red.
  2. White.
    All humans have a mixture of both muscles.
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19
Q

Describe red skeletal muscle fibres?

A

Slow twitch muscle fibres - aerobic.

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20
Q

What do the red skeletal muscle fibres contain structurally?

A

High content of the following:
1. Mitochondria.
2. Myoglobin.
3. Succinic dehydrogenase.
4. Oxidative enzymes.

Low content of:
1. Myosin ATPase.

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21
Q

Describe white skeletal muscle fibres?

A

Fast twitch muscles - anaerobic.

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22
Q

What do the white muscle fibres contain structurally?

A

Low content of following:
1. Mitochondria.
2. Myoglobin.
3. Succinic dehydrogenase.
4. Oxidative enzymes.

High content of following:
1. Glycogen.
2. Phosphorylase.
3. Myosin ATPase.

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23
Q

Describe the nervous supply of skeletal muscle?

A

Each individual fibre receives a motor nerve fibre.

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24
Q

What is a muscle spindle?

A

Group of individual fibres (up to 10).

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25
Q

Where can you find muscle spindle?

A

Embedded among the ordinary skeletal muscle.

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26
Q

What holds the muscle spindles together?

A

Connective tissue capsule. These fibres lay within a cigar-shaped or fusiform capsule.

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27
Q

What are fibres in muscle spindles called?

A

Intra-fusal.

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28
Q

What are ordinary skeletal muscle fibres called?

A

Extra-fusal.

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29
Q

Describe muscle spindles in muscles that do small movement?

A

These fibres are constantly in position and have high numbers of fibres relative to the seize of their muscle bulk e.g. 368 fibres in latiissimus dorsi and 80 fibres in abductor pollicis brevis.

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30
Q

What are intra-fusal muscle fibres innervated by?

A

Gamma motor neurons of the anterior horn.

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31
Q

What are extra-fusal muscle fibres innervated by?

A

Large A cells.

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32
Q

What is the function of muscle spindles?

A

To act as one type of sensory receptor that transmitts information on the state of the contraction of muscles in which they lie. They transmit this information to the central nervous system.

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33
Q

Where do the afferent fibres of nerves that supply spindles come from?

A

[Afferent fibres - types 1a, 2].
Come from primary (annulospiral) and secondary (flower-spray) endings that wrap themselves around parts of the spindle cells.

34
Q

What are the ways in which skeletal muscle can be arranged?

A
  1. Parallel.
  2. Oblique.
    Arranged in these two ways to the line of pull of the whole muscle.
35
Q

Describe parallel arrangement in skeletal muscle?

A

Maximum range of mobility is assured.

36
Q

Describe oblique arrangement in skeletal muscle?

A

Range of mobility is decreased but there is increased force of pull of the muscle. The muscles lay oblique to the line of pull of the whole muscle.

37
Q

Give an example of muscle with parallel fibres?

A
  1. Sartorius.
  2. Rectus abdominis.
  3. Infrahyoid group.
  4. Extrinsic eye muscles.
  5. Anterior and posterior fibres of deltoid.
  6. Flank muscles of the abdomen.
  7. Intercostals.
38
Q

What are the type of oblique arrangements of muscles?

A
  1. Unipennate.
  2. Bipennate.
  3. Multipennate.
39
Q

Describe unipennate muscles?

A

The tendon goes along one margin of the muscle and the fibres slope into one side of the tenon. It looks like a feather split pattern.

40
Q

What is an example of a unipennate muscle?

A

Flexor pollicis longus.

41
Q

Describe bipennate muscles?

A

The tendon forms at the centre (fibrous septum) and it enlarges distally to form the tendon proper. The msucle fibres will form onto each side of the central tendon - ordinary feather pattern.

42
Q

What is an example of a bipennate muscle?

A

Rectus femorus - the muscle fibres slope upwards towards the central septum.

43
Q

Describe multipennate muscles?

A
  1. Bipennate masses laying side by side e.g. acromial fibres of deltoid.
  2. Cylindrical muscle within each a central tendon forms. Fibres form into each of the tendons e.g. tibialis anterior.
44
Q

What is the main bulk of multipennate muscles?

A

Short fibres that slope between two aponeroses, downwards from the deep to the superficial.

45
Q

What happens when muscles contract in parallel arrangement?

A

There is equal shortening of the whole muscle.

46
Q

What happens when muscles contract in unipennate and multipennate muscles?

A

If there is some shortening of muscle fibres in these muscles there is less shortening of the whole muscle. Because of this there is compensation by a corresponding fain in force of pull.

47
Q

What is the proportion of oblique to longitudinal muscle fibres in oblique muscles?

A

Greater number of oblique fibres, the more oblique fibres there are there is a greater overall gain of power in the muscle as a whole. These are found in muscles that require great power and less range of movement.

48
Q

Describe the surface appearance of muscles?

A
  1. Wholly fleshy.
  2. Largely aponeurotic.
  3. Mixture.
49
Q

What does it mean if the surface of a muscle is largely aponeurotic?

A

It means that the muscle bears heavily on adjacent structures.

50
Q

what does it mean if the surface of a muscle is fleshy?

A

There is no pressure.

51
Q

What is origin of muscle?

A

Where the muscle originates from/starting point. The first attachment/upper attachment.

52
Q

What is the insertion point of muscles?

A

Where the muscle goes to and attaches to/lower attachment.

53
Q

What type of marking will fleshy muscle leave on bone?

A

No mark, or flattened or depressed.

54
Q

What type of marking will tendons or ligaments leave on bones?

A

Smooth mark on the bone.
E.g. spinati, tibialis anterior, patellar ligament, obturator tendons on femur.

55
Q

What type of marking will mixture of flesh and tendon or aponeurosis leave on bones?

A

Rough mark e.g. ulnar tuberosity, linea aspera.

56
Q

Where does flat muscle on flat bones originate from?

A

Set back from the edge of the bone in a curved line.

57
Q

What is the bare area in flat muscle and flat bone?

A

Bare area - this is where the contracting muscle slides.

58
Q

What is the purpose of a bare area?

A

To allow for greater range of movement of the contracting muscle fibres.

59
Q

What is the bare area occupied by?

A

Bursa - clasically large size.

60
Q

What else can bursa do?

A

Some bursa communicate with nearby joint (subscapularis, ilacus) - this can spread infections.

61
Q

What do other bursa do?

A

Remain separate from the joint - supraspinatus, obturator internus.

62
Q

What does the temporalis muscle do?

A

Fibres arise from the whole of the temporal fossa down to the infratemporal crest - no bursa.

63
Q

What is action of a muscle?

A

Bringing origin and insertion sites closer together - shortening of the muscle (isotonic contraction.

64
Q

What is a “prime mover”?

A

Where the main desired movement of isotonic contraction occurs in a muscle e.g. when biceps is required to flex the elbow.

65
Q

What is it when a muscle acts as an antagonist?

A

Stretching of the muscle, classically relaxing but in a controlled manner to assist the prime mover e.g. triceps acts as an antagonist to the prime mover biceps.

66
Q

What is a fixator action in muscles?

A

Stabilise one attachment of a muscle so the other attachment can move e.g. muscles holding scapula steady are fixators when the deltoid moves the humerus.

67
Q

What is a synergists action in muscles?

A

Prevent unwanted movement e.g. long flexors of fingers pass across the wrist joint before getting to the finers, when fingers flex, muscles such as flexor and extensor carpi ulnaris act as synergists to stabilise the wrist so the wrist doesn’t move and only the fingers.

68
Q

What happens when a muscle isometrically contracts?

A

There is an increase in tension but the length of the muscle stays the same.

69
Q

How do blood vessels supply muscles?

A

Arteries and vein with the motor nerve pierce the surface. Vessels from the muscle belly then go to supply the adjoining tendon.

70
Q

What nerves supply skeletal muscle?

A

Somatic nerves - via one or more motor branches (these also contain afferent and autonomic fibres.

71
Q

What are efferent fibres in spinal nerves?

A

Axons of large a anterior horn cells of spinal cord.

72
Q

Where do efferent fibres go?

A

To extrafusal fibres.

73
Q

What do small gamma cells supply/

A

Spindle fibres.

74
Q

Muscles supplied by cranial nerves receive what supply?

A

Motor nuclei of axons of cranial nerves.

75
Q

What nervous system supplies muscles of the body wall?

A

Cutaneous nerves on their way to the skin.

76
Q

What happens with muscles in the limb?

A

When nerve pierces a. muscle it supplies the muscle and the motor branch leaves the nerve proximal to the muscle. However, the nerve actually goes through a plane between distinct morphological masses that have fused together.

77
Q

What are all muscles in the limbs supplied by?

A

Branches of th elimb plexus.

78
Q

Where do flexor muscles in the limbs get their nerve supply from?

A

Anterior divisions.

79
Q

Where do extensor muscles in the limbs get their nerve supply from?

A

Posterior divisions.

80
Q

What is the percentage of afferent fibres to nerves of body wall muscles of limb muscles?

A

40% afferent fibres.

81
Q

What do the afferent fibres do?

A

Innervate muscle spindles and mediate proprioceptive impulses.

82
Q

Describe the nerves supplying the ocular and facial muscles?

A

Cranial nerves 3, 4, 6, 7 - they do not contain sensory fibres. The proprioceptive impulses are conveyed from the muscles by local branches of the trigeminal nerve.