The diaphragm is a large muscle in the abdomen that sits below the lungs and above the stomach and other abdominal organs. The contraction of this muscle, together with the muscles of the chest, opens up the air space surrounding the lungs, lowering the air pressure around the lungs, allowing them to expand into the space, drawing in air. Most ascending forms of paralysis, such as Guillain-Barre syndrome and polio often kill the patient by paralyzing the diaphragm, thus putting the patient into respiratory arrest.