peritoneum

(pĕrətənē`əm), multilayered membrane which lines the abdominal cavity, and supports and covers the organs within it. The part of the membrane that lines the abdominal cavity is called the parietal peritoneum. The portion that covers the internal organs, or viscera, is known as the visceral peritoneum and forms the outer layer (serosa) of most of the intestinal tract. The supportive peritoneum forms a double sheet of greatly modified membrane called the mesentery. This tissues hold the organs of the digestive tract in position and convey nerves, blood vessels, and lymphatic ducts to the viscera. The space between the visceral and parietal membranes contains a watery fluid that permits the abdominal organs to slide freely against the abdominal wall. A ruptured appendix can lead to inflammation of the peritoneum, a condition known as peritonitis.

Peritoneum

a thin, semitransparent membrane with a smooth, shiny surface that lines the interior wall of the abdominal cavity and covers the organs inside it in vertebrate animals and humans.

In the normal state, the cavity between the parietal and visceral peritoneums is filled with serous fluid, which facilitates the shifting of organs in relation to each other and the abdominal wall. The total area of the peritoneum in an adult human is approximately 1.6-2.04 sq m (16,000-20,400 sq cm), and its thickness is 0.7-1.1 mm. The outer layer of the peritoneum is formed of mesothelium, and its base is composed of fibrous connective tissue. The peritoneum that covers internal organs (visceral peritoneum) is compactly knitted with them; the peritoneum covering the abdominal wall (parietal peritoneum) is united with underlying parts by an interlayer of loose connective tissue or subperitoneal fatty tissue. The diaphragmatic peritoneum lacks such an interlayer. The peritoneum is abundantly supplied with blood and lymph vessels and nerves.

Covering the wall of the abdominal cavity and the organs inside it, the peritoneum forms a system of slitlike spaces— the peritoneal cavity, which is completely closed in men and which communicates with the external environment through the opening of the Fallopian tube in women. Going from organ to organ and from organ to the wall of the abdominal cavity, the peritoneum forms ligaments, mesenteries, omenta, pouches, pits, and folds. Internal organs may penetrate through depressions in the transperitoneal space, forming hernias. Internal organs may be covered with peritoneum on all sides (intraperitoneally), on three sides (mesoperitoneally), or on only one side (extraperitoneally). Depending on the disposition of blood and lymph vessels, sections of peritoneum that primarily absorb or secrete serous fluid are distinguished; this conditions the circulation of fluid in the peritoneal cavity. In some sections of the peritoneum (on the diaphragm, in the pelvic cavity, and other sections) are located special apparatus, so-called pipes of the peritoneum, which assure especially intensive absorption of fluids. Of diseases of the peritoneum, the most dangerous is its inflammation—peritonitis.

IU. I. DENISOV-NIKOL’SKII

peritoneum

[‚per·ə·tə′nē·əm] (anatomy) The serous membrane enveloping the abdominal viscera and lining the abdominal cavity.

peritoneum

a thin translucent serous sac that lines the walls of the abdominal cavity and covers most of the viscera

peritoneum

[per″ĭ-to-ne´um] the serous membrane lining the walls of the abdominal and pelvic cavities (parietal peritoneum) and investing contained viscera (visceral peritoneum), the two layers enclosing a potential space, the peritoneal cavity.

per·i·to·ne·um

, pl.

pe·ri·to·ne·a

(per'i-tō-nē'ŭm, -ă), [TA] The serous sac, consisting of mesothelium and a thin external layer of irregular connective tissue, that lines the abdominopelvic cavity and covers most of the viscera contained therein; it forms two sacs: the peritoneal (or greater) sac and the omental bursa (lesser sac) connected by the omental foramen. Synonym(s): membrana abdominis [Mod. L. fr. G. peritonaion, fr. periteinō, to stretch over]

peritoneum

also

peritonaeum

(pĕr′ĭ-tn-ē′əm)n. pl. peri·tonea also peri·tonaea (-tn-ē′ə) The serous membrane that lines the walls of the abdominal cavity and folds inward to enclose the viscera.

per′i·to·ne′al adj.per′i·to·ne′al·ly adv.

per·i·to·ne·um

(per'i-tŏ-nē'ŭm, -ă) [TA] The serous membrane, consisting of mesothelium and connective tissue, that lines the abdominal cavity and covers most of the viscera contained therein; it forms two sacs: the peritoneal (or greater) sac and the omental bursa (lesser sac), connected by the epiploic foramen. [Mod. L. fr. G. peritonaion, fr. periteinō, to stretch over]

peritoneum

(pĕr″ĭ-tō-nē′ŭm) [LL., Gr. peritonaion]

PERITONEUM: Seen laparoscopically (mag. ×½)The largest serous membrane of the body, made up of the following five different folds: the greater omentum, lesser omentum, falciform ligament, mesentery, and mesocolon. These folds line the abdominal cavity and are reflected over the viscera. They connect organs within the abdomen together and protect and support the organs.

Examination

Diseases that affect the peritoneum can be assessed with gentle and careful percussion and palpation of the abdomen. Localized or diffuse peritonitis, for example, may be evident when the abdomen is tapped with a percussing finger (the patient will wince, guard the abdomen, and complain that the percussion is very painful); it may also be evident when the abdominal wall is gently depressed and then released (release of the examining hand causes guarding and discomfort). Fluid within the peritoneum (ascites) may be suggested by shifting dullness on percussion of the abdominal wall, or by the detection of a fluid wave when one hand depresses and releases on one side of the abdomen, while the other hand gently holds the opposite side.

See: illustration

parietal peritoneum

Peritoneum lining the abdominal walls and the undersurface of the diaphragm.

visceral peritoneum

Peritoneum that invests the abdominal organs. The peritoneum holds the viscera in place by its folds, which are called the mesentery.

peritoneum

The double-layered, serum-secreting membrane that lines the inner wall of the ABDOMEN and covers, and to some extent supports, the abdominal organs. The fluid secreted by the peritoneum acts as a lubricant to allow free movement of organs such as the intestines. The peritoneum contains blood vessels, lymph vessels and nerves. From the Greek peri , round about, and teinein , to stretch.

peritoneum

the thin membrane of mesodermal origin that lines the body cavity covers the heart, and forms mesenteries.

Peritoneum

The transparent membrane lining the abdominal cavity that holds organs such as the intestines in place.Mentioned in: Adhesions, Dialysis, Kidney, Hernia Repair, Peritonitis

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Words related to peritoneum

noun a transparent membrane that lines the abdominal cavity in mammals and covers most of the viscera

Related Words