<Tr> <Th_colspan="2"> Identifiers </Th> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> The muscles of respiration are those muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity . The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing . Additional' accessory muscles of respiration' are typically only used under conditions of high metabolic demand (e.g. exercise) or respiratory dysfunction (e.g. an asthma attack). However, in instances where these accessory muscles become stiff and hard, expansion of the rib cage can be restricted . Maintenance of the elasticity of these muscles is crucial to the health of the respiratory system and to maximize its functional capabilities . </P> <P> The diaphragm is the major muscle responsible for breathing . It is a thin, dome - shaped muscle that separates the abdominal cavity from the thoracic cavity . During inhalation, the diaphragm contracts, so that its center moves caudally (downward) and its edges move rostrally (upward). This compresses the abdominal cavity, raises the ribs upward and outward and thus expands the thoracic cavity . This expansion draws air into the lungs . When the diaphragm relaxes, elastic recoil of the thoracic wall causes the thoracic cavity to contract, forcing air out of the lungs . </P>

The respiratory center regulate the activities of the respiratory muscles by
find me the text answering this question