Session 1.1g - TeachMeAnatomy - Muscles of the Thoracic Cage

Question 1

How many muscles make up the thoracic cage?

Answer 1

Five

Question 2

What are the muscles that make up the thoracic cage?

Answer 2

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

Question 3

What do the muscles of the thoracic cage do?

Answer 3

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

Question 4

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

Answer 4

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

Question 5

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?

Answer 5

• Pectoralis major
• Pectoralis minor
• Serratus anterior
• Scalene muscles

Question 6

Where do the intercostal muscles lie?

Answer 6

In the intercostal spaces between ribs.

Question 7

Which muscles lie in the intercostal spaces between ribs?

Answer 7

Intercostal muscles

Question 8

How are the intercostal muscles organised?

Answer 8

Into three layers

• external
• internal
• innermost

Question 9

How many external intercostal muscles are there?

Answer 9

11 pairs

Question 10

In what direction do the external intercostals run?

Answer 10

Inferoanteriorly from the rib above to the rib below

Question 11

What are the external intercostals continuous with?

Answer 11

The external oblique of the abdomen.

Question 12

What are the attachments of the external intercostals?

Answer 12

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

Question 13

Where do the external intercostals originate?

Answer 13

Lower border of the rib

Question 14

Where do the external intercostals insert?

Answer 14

Superior border of the rib below

Question 15

What is the action of the external intercostals?

Answer 15

Elevates the ribs, increasing the thoracic volume

Question 16

What is the innervation of the external intercostals?

Answer 16

Intercostal nerves (T1-T11).

Question 17

What type of muscles are internal intercostals?

Answer 17

Flat muscles

Question 18

Where do the internal intercostals lie?

Answer 18

Deep to the external intercostals

Question 19

What direction do the internal intercostals run?

Answer 19

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

Question 20

Compare and contrast the internal intercostals?

Answer 20

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

Question 21

What are the internal intercostals continuous with?

Answer 21

The internal oblique muscle of the abdominal wall

Question 22

What are the attachments of the internal intercostals?

Answer 22

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

Question 23

Where do the internal intercostals originate?

Answer 23

From the lateral edge of the costal groove

Question 24

Where do the internal intercostals insert?

Answer 24

Into the superior surface of the rib below

Question 25

What is the action of the internal intercostals?

Answer 25

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

Question 26

What does the interosseous part of the internal intercostals do?

Answer 26

Reduces the thoracic volume by depressing the ribcage

Question 27

What do the interchondral part of the internal intercostals do?

Answer 27

Elevates the ribs

Question 28

What is the innervation of the internal intercostals?

Answer 28

Intercostal nerves (T1-T11)

Question 29

How do the external intercostals increase thoracic volume?

Answer 29

By elevating the ribs

Question 30

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

Answer 30

Increases thoracic volume

Question 31

How do the internal intercostals reduce thoracic volume?

Answer 31

The interosseous part depresses the ribcage.

Question 32

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

Answer 32

Reduce the thoracic volume

Question 33

What are the deepest intercostal muscles?

Answer 33

The innermost intercostals

Question 34

The innermost intercostals are similar in structure to which muscles?

Answer 34

The internal intercostals

Question 35

How are the internal and innermost intercostals separated?

Answer 35

By the intercostal neurovascular bundle

Question 36

What does the intercostal neurovascular bundle separate?

Answer 36

The internal and innermost intercostals.

Question 37

Where are the innermost intercostals found?

Answer 37

In the most lateral portion of the intercostal spaces.

Question 38

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

Answer 38

The innermost intercostals

Question 39

What are the attachments of the innermost intercostals?

Answer 39

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

Question 40

What is the origin of the innermost intercostals?

Answer 40

The medial edge of the costal groove

Question 41

Where do the innermost intercostals insert?

Answer 41

The superior surface of the rib below

Question 42

What is the action of the innermost intercostals?

Answer 42

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

Question 43

What does the interosseous part of the innermost intercostals do?

Answer 43

Reduce the thoracic volume

Question 44

How do the innermost intercostals reduce the thoracic volume?

Answer 44

The interosseous part depresses the ribcage

Question 45

What does the interchondral part of the innermost intercostals do?

Answer 45

Elevates the ribs

Question 46

Which part of the innermost intercostals elevates the ribs?

Answer 46

The interchondral part

Question 47

What is the innermost intercostals innervated by?

Answer 47

The intercostal nerves (T1-T11).

Question 48

The muscles of the thoracic cage are continuous with ___?

Answer 48

The transversus abdominis inferiorly

Question 49

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

Answer 49

Transversus thoracis

Question 50

What are the attachments of transversus thoracis?

Answer 50

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

Question 51

Where does transversus thoracis originate?

Answer 51

From the posterior surface of the inferior sternum

Question 52

Where does transversus thoracis insert?

Answer 52

The internal surface of costal cartilages 2-6.

Question 53

What is the action of transversus thoracis?

Answer 53

To weakly depress the ribs.

Question 54

What is the innervation of transversus thoracis?

Answer 54

Intercostal nerves (T1-T11).

Question 55

Where are the subcostal muscles found?

Answer 55

In the inferior portion of the thoracic wall

Question 56

What do the subcostals comprise?

Answer 56

Thin slips of muscle

Question 57

Where do the subcostals run from?

Answer 57

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

Question 58

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

Answer 58

Subcostals

Question 59

What direction do the subcostals run in?

Answer 59

The direction of the fibres parallels that of the innermost intercostal

Question 60

What are the attachments of the subcostals?

Answer 60

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.

Question 61

Where do the subcostals originate?

Answer 61

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

Question 62

Where do the subcostals insert?

Answer 62

The superior border of the rib 2 or 3 below.

Question 63

What is the action of the subcostals?

Answer 63

Share the action of the internal intercostals | Reduces the thoracic volume by depressing the ribcage

Question 64

What is the innervation of the subcostals?

Answer 64

Intercostal nerves

Question 65

Fig. 1 Label and caption the image

Answer 65

- Internal intercostals - External intercostals - Pectoralis minor - Serratus anterior The external and internal intercostals of the thoracic wall.

Question 66

Fig. 2 Label and caption the image

Answer 66

- Internal intercostals - Diaphragm - Transversus thoracis View of the internal aspect of the thoracic wall. The internal intercostal and transverse thoracis muscles are visible.

Question 67

How many pairs of external intercostal muscles are there? A. 9 B. 10 C. 11 D. 12

Answer 67

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

Question 68

Which of the intercostal muscles work to elevate the ribs? A. Innermost intercostals B. Internal intercostals C. External intercostals D. Transversus thoracis

Answer 68

C. External intercostals

Question 69

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

Answer 69

B. 2-6