: a device that limits the aperture of a lens or optical system
: a molded cap usually of thin rubber fitted over the uterine cervix to act as a mechanical contraceptive barrier
Illustration of DIAPHRAGM
Dome-shaped muscular and membranous structure between the thoracic and abdominal cavities. The principal muscle used in respiration, it is also important in coughing, vomiting, excretion, and other expulsive functions. Spasms of the diaphragm produce hiccups. The aorta passes behind the diaphragm; the inferior vena cava and esophagus pass through it. Protrusion of part of the stomach above the diaphragm is called a hiatal hernia.