The diaphragm is basically a dome shaped skeletal muscle that is found below the lungs and which separates the thoracic cavity, the chest cavity, where the lungs are found, and our abdominal cavity, which is found beneath our diaphragm. So let's describe how inhalation actually takes place. So the diaphragm, as well as these external intercostal muscles found between our ribs, begin to actually use ATP and contract. So the process of inhalation is an active process because it requires using ATP for muscle contraction. Now, as the diaphragm begins to contract, it begins to flatten out. So it moves in the following general direction.