Answer:
The diaphragm muscle contacts and relaxes to force the intake and expulsion of air from the lungs.
Step-by-step explanation:
The diaphragm is a large, dome-shaped skeletal muscle. It is very thin, and is located at the base of the chest just above the abdomen. It plays a very important role during respiration or breathing by forcing the intake and expulsion of air from the lungs.
During inhalation, this muscle contracts, and flattens- in the process, a vacuum is created, effectively pulling air into the space. In exhalation the muscle relaxes, and is no longer flattened, this reduces the volume of the region, forcing air out of the lungs. These contractions occur rhythmically and continuously.