Muscles of the Thoracic Wall

Question 1

external intercostals

Answer 1

SA:
+ inferior border of ribs

IA:
+ superior border of ribs below

N:
+ intercostal nerves

A:
+ during forced inspiration: elevates ribs

Question 2

internal intercostals

Answer 2

SA:
+ inferior border of ribs

IA:
+ superior border of ribs below

N:
+ intercostal nerves

A:
+ during forced inspiration:
+ interosseous part: depresses ribs
+ interchondral part: elevates ribs

Question 3

innermost intercostals

Answer 3

SA:
+ inferior border of ribs

IA:
+ superior border of ribs below

N:
+ intercostal nerves

A:
+ during forced inspiration:
+ interosseous part: depresses ribs
+ interchondral part: elevates ribs

Question 4

transversus thoracis

Answer 4

SA:
+ posterior surface of lower sternum

IA:
+ internal surface of costal cartilages 2-6

N:
+ intercostal nerves

A:
+ weakly depresses ribs