The muscles of the thoracic cage

Question 1

how many muscles make up the thoracic cage?

Answer 1

There are five muscles that make up the thoracic cage

Question 2

what are the muscles that make up the thoracic cage?

Answer 2

intercostals (external, internal and innermost),
subcostals,
transversus thoracis

Question 3

what do the muscles of the thoracic cage act to do?

Answer 3

change the volume of the thoracic cavity during respiration

Question 4

what other muscles are there aside from the ones that make up the thoracic cage?

Answer 4

There are some other muscles that do not comprise the thoracic wall, but do attach to it

Question 5

what are the muscles that attach to the thoracic wall?

Answer 5

pectoralis major, minor
serratus anterior
scalene muscles

Question 6

which muscles lie in the intercostal spaces between ribs?

Answer 6

The intercostal muscles lie in the intercostal spaces between ribs

Question 7

how are the intercostal muscles arranged?

Answer 7

into 3 layers:
External Intercostals
Internal Intercostals
Innermost Intercostals

Question 8

how many pairs of external intercostal muscles are there?

Answer 8

There are 11 pairs of external intercostal muscles

Question 9

where do the external intercostal muscles travel?

Answer 9

They run inferoanteriorly from the rib above to the rib below

Question 10

what are the external intercostal muscles continuous with?

Answer 10

continuous with the external oblique of the abdomen

Question 11

what does the external intercostal muscle originate?

Answer 11

at the lower border of the rib

Question 12

where does the external intercostal muscle insert into?

Answer 12

inserting into the superior border of the rib below

Question 13

what is the action of the external intercostal muscle?

Answer 13

Elevates the ribs, increasing the thoracic volume

Question 14

what is the innervation of the external intercostal muscle?

Answer 14

Intercostal nerves (T1-T11)

Question 15

where do the internal intercostal muscles lie?

Answer 15

These flat muscles lie deep to the external intercostals

Question 16

where do the internal intercostal muscles run?

Answer 16

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

Question 17

what is the internal intercostal muscle continuous with?

Answer 17

They are continuous with the internal oblique muscle of the abdominal wall

Question 18

what is the origin of the internal intercostal muscle?

Answer 18

Originate at the lower border of the rib
Actions: The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondral part elevates the ribs.
Innervation: Intercostal nerves (T1-T11)

Question 19

where does the internal intercostal muscle insert into?

Answer 19

inserting into the superior border of the rib below

Question 20

what are the 2 parts of the internal intercostal muscle?

Answer 20

interosseous and interchondral

Question 21

what is the action of the interosseous part of the internal intercostal muscle?

Answer 21

reduces the thoracic volume by depressing the ribcage

Question 22

what is the action of the interchondral part of the internal intercostal muscle?

Answer 22

elevates the ribs

Question 23

where do the innermost intercostal muscles lie? what are they similar in structure to?

Answer 23

These muscles are the deepest of the intercostal muscles, and are similar in structure to the internal intercostals

Question 24

what are innermost intercostal muscles separated from the internal intercostals by?

Answer 24

They are separated from the internal intercostals by the intercostal neurovascular bundle

Question 25

where are intercostal neurovascular bundle found?

Answer 25

in the most lateral portion of the intercostal spaces

Question 26

where do the innermost intercostal muscles originate from?

Answer 26

Originate at the lower border of the rib

Question 27

where do the innermost intercostal muscles insert into?

Answer 27

superior border of the rib below

Question 28

what are the different sections of the innermost intercostal muscles?

Answer 28

interosseous part and interchondral part

Question 29

what is the action of the interosseous part of the innermost intercostal muscles?

Answer 29

reduces the thoracic volume by depressing the ribcage

Question 30

what is the action of the interosseous part of the innermost intercostal muscles?

Answer 30

elevates the ribs

Question 31

what is the nerve innervation of the innermost intercostal muscles?

Answer 31

Intercostal nerves (T1-T11)

Question 32

what are the muscles of the thoracic cage continuous with? where?

Answer 32

These muscles of the thoracic cage are continuous with transversus abdominis inferiorly

Question 33

where does the transversus abdominis originate from? attach?

Answer 33

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

Question 34

what is the action of the transversus abdominis?

Answer 34

Weakly depress the ribs

Question 35

what is the innervation of the transversus abdominis?

Answer 35

Intercostal nerves (T1-T11)

Question 36

where are the subcostal muscles found?

Answer 36

in the inferior portion of the thoracic wall. The direction of the fibres parallels that of the innermost intercostal

Question 37

what do the subcostal muscles consist of?

Answer 37

They comprise of thin slips of muscle, which run from the internal surface of one rib, to second and third ribs below

Question 38

what do the direction of the fibres of subcostal muscle run?

Answer 38

The direction of the fibres parallels that of the innermost intercostal

Question 39

what is the attachment of the subcostal muscle? origin and insertion

Answer 39

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 40

what is the action of the subcostal muscle?

Answer 40

Share the action of the internal intercostals

Question 41

what innervates the subcostal muscle?

Answer 41

Intercostal nerves