Thoracic Wall Muscles (Quiz 1)

Question 1

What are the 7 muscles of the thoracic wall?

Answer 1

1) serratus posterior superior
2) serratus posterior inferior
3) external intercostal
4) internal intercostal
5) innermost intercostal
6) subcostal
7) transversus thoracis

Question 2

What is the primary muscle of inspiration?

Answer 2

the diaphragm

Question 3

What muscles are mainly isometric muscles maintaining the tone without producing movement?

Answer 3

external and internal intercostal muscles

Question 4

What is the origin/superior attachment for the serratus posterior superior?

Answer 4

-nuchal ligament
-SP of C7-T3 vertebrae

*note: this origin is very close to rhomboid minor origin BUT not the same

Question 5

What is the insertion/inferior attachment for the serratus posterior superior?

Answer 5

superior borders of 2nd-4th ribs

Question 6

What innervates the serratus posterior superior?

Answer 6

2nd-5th intercostal nerves

Question 7

What is the action of the serratus posterior superior?

Answer 7

proprioception (elevate ribs)

*note: this is opposite of serratus posterior inferior, which depresses the ribs

Question 8

What is the origin/inferior attachment of the serratus posterior inferior?

Answer 8

SP of T11-L2 vertebrae

Question 9

What is the insertion/superior attachment of the serratus posterior inferior?

Answer 9

inferior borders of 8th-12th ribs near their angles

Question 10

What innervates the serratus posterior inferior?

Answer 10

anterior rami to T9-T12 thoracic spinal nerves

Question 11

What is the action of the serratus posterior inferior?

Answer 11

proprioception (depress the ribs)

*note: this is opposite of serratus posterior superior, which elevates the ribs

Question 12

What is the origin/superior attachment of the external and internal intercostal muscles AND innermost intercostal muscles?

Answer 12

inferior border of the ribs

*note: this is opposite of the insertion

Question 13

What is the insertion/inferior attachment of the external and internal intercostal muscles AND innermost intercostal muscles?

Answer 13

superior border of the ribs below

*note: this is opposite of the origin

Question 14

What innervates the external and internal intercostal muscles AND innermost intercostal muscles AND subcostal muscle AND transversus thoracis?

Answer 14

intercostal nerves

Question 15

What is the action of the external intercostal?

Answer 15

elevate ribs during forced respiration

Question 16

How many external intercostal muscles are there?

Answer 16

11 pairs- end anteriorly as external intercostal membranes

continue inferiorly as external oblique

Question 17

What are the actions of the internal intercostal muscles AND innermost intercostal muscles?

Answer 17

during active or forced inspiration
-interosseous part depresses the ribs
-interchondral part elevates the ribs

*note: the subcostal muscle probably has this same action but it is not fully known

Question 18

How many internal intercostal muscles are there?

Answer 18

11 pairs- end posteriorly as internal intercostal membranes

continue inferiorly as internal oblique

Question 19

What is the origin/superior attachment of the subcostal?

Answer 19

internal surface of lower ribs near their angles

Question 20

What is the insertion/inferior attachment for the subcostal?

Answer 20

superior borders of 2nd and 3rd ribs below

Question 21

What is the origin/inferior attachment for the transversus thoracis?

Answer 21

posterior surface of lower sternum

Question 22

What is the insertion/superior attachment for the transversus thoracis?

Answer 22

internal surface of costal cartilages 2-6

Question 23

What is the potential action of the transversus thoracis?

Answer 23

weakly depresses ribs and proprioception