As we have seen, breathing is a combination of many factors. These factors are integrated and controlled by the nervous system.
Respiratory reflexes are controlled by the respiratory center found in the medullary portion of the hindbrainstem. The level of carbon dioxide
(CO2) in the circulating blood is one of the major influences upon the respiratory reflex.
The individual intercostal nerves innervate the intercostal muscles.
The muscles attached to and moving the rib cage are innervated by their appropriate nerves.
The diaphragm is innervated by its own individual pair of phrenic nerves.