Thoracic Wall

Question 1

External intercostal

Answer 1

Origin: inferior border of ribs
Insertion : superior border of ribs below
Innervation: intercostal nerve
Action : during forced inspiration , elevate ribs

Question 2

Internal intercostal

Answer 2

Origin : inferior border of ribs
Insertion : superior border of ribs below
Innervation : intercostal nerve
Action : during forced respiration , interosseous part depresses ribs; interchondral part elevates ribs

Question 3

Innermost intercostal

Answer 3

Origin: inferior border of ribs
Insertion : superior border of ribs below
Innervation : intercostal nerve
Action : during forced respiration, interosseous part depresses ribs; interchondral part elevates ribs

Question 4

Transverse thoracis

Answer 4

Origin : posterior surface of lower sternum
Insertion : internal surface of costal cartilages 2-6
Innervation : intercostal nerve
Action : weakly depresses ribs