Diaphragm is term used in physiology to describe several large muscle groups which are found only in humans and other mammals. These muscles are structural components that separate two adjacent regions of the body. Diaphragms in the human body include the pelvic diaphragm, the urogenital diaphragm, and the thoraco-abdominal diaphragm. The latter one, which is commonly referred to as "the" diaphragm, is the muscle that separates the chest cavity (which contains the heart and lungs), from the abdomen (which contains the stomach, intestines, and other organs.)

The term comes from the Greek word "diaphragma," meaning "barrier." The thoraco-abdominal diaphragm, which is located in the midriff, consists of muscle and membrane tissue and is attached to the rib cage. It has three openings for the esophagus, aorta, and vena cava. The muscle has a slightly concave structure and it arches over the liver on the right and the stomach...