Thoracic Wall Muscles

Question 1

External intercostal

Answer 1

O: inferior boarder of rib
I: superior boarder of rib below
A: elevates rib
I: intercostal nerve

Question 2

Internal intercostal

Answer 2

O: superior boarder of rib below
I: inferior boarder of rib
A: elevates rib; others depresses
I: intercostal nerve

Question 3

Innermost thoracis

Answer 3

O: superior boarder of rib below
I: inferior boarder of rib
A: acts similar to internal intercostal
I: intercostal nerve

Question 4

Transverse thoracis

Answer 4

O: internal surfaces of costal cartilage 2-6
I: posterior surface of lower sternum
A: depresses ribs and costal cartilage
I: intercostal nerve

Question 5

Subcostal

Answer 5

O: internal surfaces of lower ribs near their angles
I: superior boarder of second or third ribs below
A: depresses ribs
I: intercostal nerve

Question 6

Levator costarum

Answer 6

O: transverse processes of C7 and T1-T11
I: subjacent ribs between tubercle and angle
A: elevates rib
I: posterior rami of C8-T11