What muscular organ is responsible for drawing air in and out of the lungs?

The diaphragm is the primary muscular organ responsible for the process of breathing. It is a dome-shaped muscle located beneath the lungs and separates the thoracic cavity from the abdominal cavity. During inhalation, the diaphragm contracts and flattens, increasing the volume of the thoracic cavity and creating a negative pressure that draws air into the lungs. During exhalation, the diaphragm relaxes and returns to its dome shape, which decreases the volume of the thoracic cavity and pushes air out of the lungs.

Other muscle groups, such as the intercostal muscles, assist in the breathing process but are not the main drivers. The intercostal muscles help expand and contract the rib cage during breathing, while abdominal muscles can support exhalation, particularly during forceful breathing. However, it is the diaphragm that is primarily responsible for the fundamental process of inhalation and exhalation, making it the correct answer in this context.