Question: when are the abdominal muscles involved in breathing

title: Muscles of respiration
text: 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 . 

Answer: answer: The diaphragm is the major muscle responsible for breathing. During inhalation, the diaphragm contracts, so that its center moves caudally (downward) and its edges move rostrally (upward).
answer: During inhalation , the diaphragm contracts which compresses the abdominal cavity , raises the ribs upward and outward and thus expands the thoracic cavity. When the diaphragm relaxes, the cavity contracts , forcing air out of the lungs.