diaphragm

1. The musculomembranous partition between the abdominal and thoracic cavities. SYN: diaphragma (2) [TA], interseptum, midriff, phren (1). 2. A thin disk pierced with an opening, used in a microscope, camera, or other optical instrument in order to shut out the marginal rays of light, thus giving a more direct illumination. 3. A flexible ring covered with a dome-shaped sheet of elastic material used in the vagina to prevent pregnancy. 4. In radiography, a grid (2) or a lead sheet with an aperture. See collimator. [G. diaphragma]

- aperture d. a metal device that limits the area of the beam emerging from an x-ray tube.

- Bucky d. in radiography, a d. with a moving grid that avoids grid shadows. SYN: Potter-Bucky d..

- d. of mouth SYN: mylohyoid (muscle).

- pelvic d. the paired levator ani and coccygeus muscles together with the fascia above and below them. SYN: d. of pelvis, diaphragma pelvis.

- d. of pelvis SYN: pelvic d..

- Potter-Bucky d. SYN: Bucky d..

- d. sellae SYN: diaphragma sellae.

- sellar d. diaphragma sellae.

- d. of sella turcica SYN: diaphragma sellae.

- urogenital d. an obsolete concept of a trilaminar, triangular sheet of muscle and fascia spanning the ischiopubic rami; composed of the sphincter urethrae and the deep transverse perineal muscles (which were said to be flat muscles forming a continuous sheet), plus the perineal membrane below and a superior fascia of the d. above. Evidence of the latter is lacking. The muscle-containing space between the fascial structures was formerly referred to as the deep perineal space. The terms urogenital d. and deep perineal space are not recognized by Terminologia Anatomica due to more accurate understanding of the morphology, especially of the sphincter urethrae. SYN: diaphragma urogenitale.

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di·a·phragm 'dī-ə-.fram n

1) a body partition of muscle and connective tissue specif the partition separating the chest and abdominal cavities in mammals see PELVIC DIAPHRAGM, UROGENITAL DIAPHRAGM

2) a device that limits the aperture of a lens or optical system

3) a molded cap usu. of thin rubber fitted over the uterine cervix to act as a mechanical contraceptive barrier

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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 breast-bone 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.

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di·a·phragm (diґə-fram) 1. diaphragma (def. 1). 2. any separating membrane or structure. 3. a disk with one or more openings in it, or with an adjustable opening, mounted in relation to a lens or source of radiation by which part of the light or radiation may be excluded from the area. 4. a contraceptive device of molded rubber or other soft plastic material, fitted over the cervix uteri prior to intercourse to prevent the entrance of spermatozoa; for added efficacy, a spermicidal agent is usually placed within it. Called also contraceptive d. and vaginal d.