- n.1) (in anatomy) a thin musculomembranous dome-shaped muscle that separates the thoracic and abdominal cavities. The diaphragm is attached to the lower ribs at each side and to the breastbone and the backbone at the front and back. It bulges upwards against the heart and the lungs, arching over the stomach, liver, and spleen. There are openings in the diaphragm through which the oesophagus, blood vessels, and nerves pass. The diaphragm plays an important role in breathing. It contracts with each inspiration, becoming flattened downwards and increasing the volume of the thoracic cavity. With each expiration it relaxes and is restored to its dome shape.2) a hemispherical rubber cap fitted inside the vagina over the neck (cervix) of the uterus as a contraceptive. When combined with the use of a chemical spermicide the diaphragm provides reliable contraception with a failure rate as low as 2–10 pregnancies per 100 woman-years.
The new mediacal dictionary. 2014.