Ward: Respiratory System at a Glance

a contain an intercostal nerve, intercostal vein and intercostal artery lying just above the top of the rib

b contain the main expiratory muscles

c are stiffened during inspiration and expiration by the contraction of the intercostal muscles

d contain muscles which are too weak to maintain adequate resting ventilation if the diaphragm is paralyzed.

The Respiratory System