Session 1.1g - TeachMeAnatomy - Muscles of the Thoracic Cage Flashcards

1
Q

How many muscles make up the thoracic cage?

A

Five

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2
Q

What are the muscles that make up the thoracic cage?

A
  • The intercostals (external, internal and innermost)
  • Subcostals
  • Transversus thoracic
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3
Q

What do the muscles of the thoracic cage do?

A

These muscles act to change the VOLUME of the thoracic cavity during respiration.

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4
Q

What do pectoralis major, minor, serratus anterior and the scalene muscles have in common with regards to the thoracic cage?

A

They do not comprise the thoracic wall, but do ATTACH to it.

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5
Q

As well as the 5 muscles that makes up the thoracic cage, there are some other muscles that do not comprise the thoracic wall, but do attach to it. What are these muscles?

A
  • Pectoralis major
  • Pectoralis minor
  • Serratus anterior
  • Scalene muscles
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6
Q

Where do the intercostal muscles lie?

A

In the intercostal spaces between ribs.

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7
Q

Which muscles lie in the intercostal spaces between ribs?

A

Intercostal muscles

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8
Q

How are the intercostal muscles organised?

A

Into three layers

  • external
  • internal
  • innermost
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9
Q

How many external intercostal muscles are there?

A

11 pairs

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10
Q

In what direction do the external intercostals run?

A

Inferoanteriorly from the rib above to the rib below

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11
Q

What are the external intercostals continuous with?

A

The external oblique of the abdomen.

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12
Q

What are the attachments of the external intercostals?

A

Originate at the lower border of the rib, inserting into the superior border of the rib below.

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13
Q

Where do the external intercostals originate?

A

Lower border of the rib

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14
Q

Where do the external intercostals insert?

A

Superior border of the rib below

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15
Q

What is the action of the external intercostals?

A

Elevates the ribs, increasing the thoracic volume

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16
Q

What is the innervation of the external intercostals?

A

Intercostal nerves (T1-T11).

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17
Q

What type of muscles are internal intercostals?

A

Flat muscles

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18
Q

Where do the internal intercostals lie?

A

Deep to the external intercostals

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19
Q

What direction do the internal intercostals run?

A

Like the external intercostals, they run from the rib above to the one below, but in an opposite direction (inferoposteriorly)

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20
Q

Compare and contrast the internal intercostals?

A

Like the external intercostals they run from the rib above to the one below

However, they run in the opposite direction to external intecostals:

  • external = inferoanteriorly
  • internal = inferoposteriorly
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21
Q

What are the internal intercostals continuous with?

A

The internal oblique muscle of the abdominal wall

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22
Q

What are the attachments of the internal intercostals?

A

Originates from the lateral edge of the costal groove and inserts into the superior surface of the rib below.

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23
Q

Where do the internal intercostals originate?

A

From the lateral edge of the costal groove

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24
Q

Where do the internal intercostals insert?

A

Into the superior surface of the rib below

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25
Q

What is the action of the internal intercostals?

A

The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondal part elevates the ribs.

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26
Q

What does the interosseous part of the internal intercostals do?

A

Reduces the thoracic volume by depressing the ribcage

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27
Q

What do the interchondral part of the internal intercostals do?

A

Elevates the ribs

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28
Q

What is the innervation of the internal intercostals?

A

Intercostal nerves (T1-T11)

29
Q

How do the external intercostals increase thoracic volume?

A

By elevating the ribs

30
Q

The external intercostals elevate the ribs. What does this do?

A

Increases thoracic volume

31
Q

How do the internal intercostals reduce thoracic volume?

A

The interosseous part depresses the ribcage.

32
Q

What does depressing the ribcage (action performed by the interosseous part of the internal intercostals) do?

A

Reduce the thoracic volume

33
Q

What are the deepest intercostal muscles?

A

The innermost intercostals

34
Q

The innermost intercostals are similar in structure to which muscles?

A

The internal intercostals

35
Q

How are the internal and innermost intercostals separated?

A

By the intercostal neurovascular bundle

36
Q

What does the intercostal neurovascular bundle separate?

A

The internal and innermost intercostals.

37
Q

Where are the innermost intercostals found?

A

In the most lateral portion of the intercostal spaces.

38
Q

Which muscle is found in the most lateral portion of the intercostal spaces?

A

The innermost intercostals

39
Q

What are the attachments of the innermost intercostals?

A

Originates from the medial edge of the costal groove and inserts into the superior surface of the rib below.

40
Q

What is the origin of the innermost intercostals?

A

The medial edge of the costal groove

41
Q

Where do the innermost intercostals insert?

A

The superior surface of the rib below

42
Q

What is the action of the innermost intercostals?

A

The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondral part elevates the ribs.

43
Q

What does the interosseous part of the innermost intercostals do?

A

Reduce the thoracic volume

44
Q

How do the innermost intercostals reduce the thoracic volume?

A

The interosseous part depresses the ribcage

45
Q

What does the interchondral part of the innermost intercostals do?

A

Elevates the ribs

46
Q

Which part of the innermost intercostals elevates the ribs?

A

The interchondral part

47
Q

What is the innermost intercostals innervated by?

A

The intercostal nerves (T1-T11).

48
Q

The muscles of the thoracic cage are continuous with ___?

A

The transversus abdominis inferiorly

49
Q

The muscles of the thoracic cage are continuous with transversus abdominis inferiorly. What muscle is this known as?

A

Transversus thoracis

50
Q

What are the attachments of transversus thoracis?

A

From the posterior surface of the inferior sternum to the internal surface of costal cartilages 2-6.

51
Q

Where does transversus thoracis originate?

A

From the posterior surface of the inferior sternum

52
Q

Where does transversus thoracis insert?

A

The internal surface of costal cartilages 2-6.

53
Q

What is the action of transversus thoracis?

A

To weakly depress the ribs.

54
Q

What is the innervation of transversus thoracis?

A

Intercostal nerves (T1-T11).

55
Q

Where are the subcostal muscles found?

A

In the inferior portion of the thoracic wall

56
Q

What do the subcostals comprise?

A

Thin slips of muscle

57
Q

Where do the subcostals run from?

A

The internal surface of one rib, to second and third ribs below.

58
Q

Which muscles run from the internal surface of one rib, to the second and htird ribs below?

A

Subcostals

59
Q

What direction do the subcostals run in?

A

The direction of the fibres parallels that of the innermost intercostal

60
Q

What are the attachments of the subcostals?

A

These originate from the inferior surface of the lower ribs, near the angle of the rib. They then attach to the superior border of the rib 2 or 3 below.

61
Q

Where do the subcostals originate?

A

From the inferior surface of the lower ribs, near the angle of the rib.

62
Q

Where do the subcostals insert?

A

The superior border of the rib 2 or 3 below.

63
Q

What is the action of the subcostals?

A

Share the action of the internal intercostals

Reduces the thoracic volume by depressing the ribcage

64
Q

What is the innervation of the subcostals?

A

Intercostal nerves

65
Q

Fig. 1

Label and caption the image

A
  • Internal intercostals
  • External intercostals
  • Pectoralis minor
  • Serratus anterior

The external and internal intercostals of the thoracic wall.

66
Q

Fig. 2

Label and caption the image

A
  • Internal intercostals
  • Diaphragm
  • Transversus thoracis

View of the internal aspect of the thoracic wall. The internal intercostal and transverse thoracis muscles are visible.

67
Q

How many pairs of external intercostal muscles are there?

A. 9
B. 10
C. 11
D. 12

A

C. 11

There are 12 ribs, leaving 11 gaps in between for pairs of intercostal muscles.

68
Q

Which of the intercostal muscles work to elevate the ribs?

A. Innermost intercostals
B. Internal intercostals
C. External intercostals
D. Transversus thoracis

A

C. External intercostals

69
Q

Transversus thoracis extend from the inferior sternum to the internal costal cartilages of which ribs?

A. 1-11
B. 2-6
C. 3-5
D. 8-10

A

B. 2-6