diaphragm (redirected from lightbeam diaphragm)

diaphragm /di·a·phragm/ (di´ah-fram)

1. the musculomembranous partition separating the abdominal and thoracic cavities and serving as a major muscle aiding inhalation.

2. any separating membrane or structure.

3. a disk with one or more openings 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 device of molded rubber or other soft plastic material, fitted over the uterine cervix before intercourse to prevent entrance of spermatozoa.diaphragmat´ic

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contraceptive diaphragm  diaphragm (4).

pelvic diaphragm  the portion of the floor of the pelvis formed by the coccygeal and levator ani muscles and their fasciae.

polyarcuate diaphragm  one showing abnormal scalloping of the margins on radiographic visualization.

Potter-Bucky diaphragm  see under grid.

respiratory diaphragm  diaphragm (1).

urogenital diaphragm  traditional but no longer valid concept that fascial layers enclose the sphincter urethrae and deep transverse perineal muscles and together form a musculomembranous sheet that extends between the ischiopubic rami.

vaginal diaphragm  diaphragm (4).

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di·a·phragm (d-frm) n. 1. A musculomembranous partition separating the abdominal and thoracic cavities and functioning in respiration. Also called midriff. 2. A membranous part that divides or separates. 3. A contraceptive device consisting of a thin flexible disk, usually made of rubber, that is designed to cover the uterine cervix to prevent the entry of sperm during sexual intercourse. 4. A disk having a fixed or variable opening used to restrict the amount of light traversing a lens or optical system. dia·phrag·matic (-frg-mtk) adj.

diaphragm Top: during inhalation the diaphragm contracts downward, forcing air into the lungs Bottom: during exhalation the diaphragm relaxes upward, forcing air out of the lungs

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Diaphragm

The thin layer of muscle that separates the chest cavity containing the lungs and heart from the abdominal cavity containing the intestines and digestive organs.

Mentioned in: Chest X Ray, Esophageal Disorders, Heimlich Maneuver, Sexually Transmitted Diseases, Ventricular Assist Device

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diaphragm

[dī′əfram]

Etymology: Gk, diaphragma, partition

1 (in anatomy) a dome-shaped musculofibrous partition that separates the thoracic and abdominal cavities. The convex cranial surface of the diaphragm forms the floor of the thoracic cavity; the concave surface forms the roof of the abdominal cavity. This partition is pierced by various openings through which pass the esophagus and inferior vena cava. The diaphragm aids respiration by moving up and down. During inspiration it moves down and increases the volume of the thoracic cavity. During expiration it moves up, decreasing the volume. During deep inspiration and expiration the range of diaphragmatic movement in the adult is about 30 mm on the right side and about 28 mm on the left side. The height of this structure also varies with the degree of distension of the stomach and the intestines and with the size of the liver. It is innervated by the phrenic nerve from the cervical plexus.

2 See contraceptive diaphragm.

3 (in optics) an opening that controls the amount of light passing through an optical network.

4 a thin, membranous partition, as that used in dialysis.

5 (in radiography) a metal plate with a small opening that limits the diameter of the radiographic beam. diaphragmatic, adj.

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diaphragm (dī´fram),

n 1. a musculotendinous partition that separates the thorax and abdomen.
n 2. a metal barrier plate, often of lead, pierced with a central aperture so arranged as to limit the emerging, or useful, beam of roentgen rays to the smallest practical diameter for making radiographic exposures. See also collimation; collimator; distance, cone.

diaphragm, lead,

n a collimating device with a small opening, designed to limit the size of the outgoing x-ray beam. It is usually made of lead one-eighth of an inch thick and located between the position-indicating device and the radiographic tube itself.

See grid, Potter-Bucky.

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diaphragm

1. the musculomembranous partition separating the thoracic and abdominal cavities. On its sides, it is attached to the caudal ribs; ventrally to the sternum; at the back, to the spine. The esophagus, the aorta and vena cava, and nerves pass through the diaphragm. When relaxed, the diaphragm is convex but it flattens and moves caudally as it contracts during inhalation, thereby enlarging the chest cavity and allowing for expansion of the lungs. See also respiration.

2. any separating membrane or structure.

3. a disk with one or more openings or with an adjustable opening, mounted in relation to a lens, by which part of the light may be excluded from the area.

See also diaphragmatic.

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Potter-Bucky diaphragm

see Potter-Bucky grid.

lightbeam diaphragm

an adjustable diaphragm which is used to cone down a light beam that indicates the dimensions of an x-ray beam and marks the position of the central ray.

pelvic diaphragm

the portion of the caudal wall of the pelvis formed by the coccygeus muscles, the levator ani muscles and fascia.

slit diaphragm

see filtration membrane.

urogenital diaphragm

the musculomembranous layer superficial to the pelvic diaphragm, extending between the ischiopubic rami and surrounding the urogenital ducts.

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diaphragm

1. In optics, an aperture generally round and of variable diameter placed in a screen and used to limit the field of view of a lens or optical system (field stop). It also limits stray light (light stop). Syn. stop; aperture-stop. 2. In anatomy, a dividing membrane.

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diaphragm

Gynecology A barrier contraceptive consisting of a thin flexible rubber disk that covers the uterine cervix to prevent the entry of sperm during sexual intercourse