The breathing process is primarily controlled by:
- the diaphragm.
- rib muscles.
The diaphragm is a major muscle involved in respiration, and the rib muscles (intercostal muscles) assist with expanding and contracting the rib cage during breathing. The pharynx is part of the respiratory and digestive systems but does not control the breathing process. Blood vessels play a role in gas exchange and transporting oxygen and carbon dioxide but are not directly involved in controlling the breathing process.