peritoneo

The peritoneum, referred to in Italian as peritoneo, is a continuous serous membrane that lines the abdominal cavity and surrounds most abdominal organs. It consists of a layer of mesothelial cells supported by connective tissue. It has two main components: the parietal peritoneum, lining the abdominal wall, and the visceral peritoneum, covering the organs. The peritoneal cavity between these layers contains a small amount of lubricating peritoneal fluid that reduces friction during organ movement.

The peritoneum forms reflections known as mesenteries, omenta, and ligaments, which suspend viscera, transmit blood vessels and nerves, and help stabilize the arrangement of abdominal contents. Organs are classified as intraperitoneal (enclosed by visceral peritoneum and connected by mesenteries) or retroperitoneal (against the posterior abdominal wall with only partial peritoneal covering). Intraperitoneal organs include the stomach, liver (primarily), spleen, jejunum, ileum, transverse colon, and sigmoid colon, among others.

Functions of the peritoneum include lubrication of surfaces, facilitation of organ movement, compartmentalization of the abdominal cavity, fat storage, and participation in immune defense and fluid regulation. Innervation differs by layer: the parietal peritoneum has somatic sensory nerves and is well localized for pain, whereas the visceral peritoneum is supplied by autonomic nerves and conveys poorly localized pain.

Clinically, the peritoneum is involved in conditions such as peritonitis (inflammation), ascites (fluid accumulation in the cavity), and peritoneal dialysis, which uses the peritoneal membrane as a dialysis surface. Embryologically, it arises from the intraembryonic coelom and forms the mesenteries and omental folds that organize the gut’s position.