Parietalperitoneum

Parietal peritoneum, commonly referred to as the parietal peritoneum, is the serous membrane lining the internal surface of the abdominal and pelvic walls and the inferior surface of the diaphragm. It forms the outer layer of the peritoneal cavity and is separated from the underlying organs by a thin film of peritoneal fluid. The visceral peritoneum covers most intraperitoneal organs, and the two layers are continuous at the reflection points that form mesenteries, ligaments, and omenta.

Structure and relations: The parietal peritoneum is a simple squamous epithelium (mesothelium) supported by connective tissue. It is firmly attached to the transversalis fascia and the inner aspects of the abdominal and pelvic walls. It lines the diaphragmatic and pelvic portions of the cavity and extends to lines the lower surface of the diaphragm, the lateral abdominal walls, and the superior aspects of the pelvic cavity.

Innervation and sensation: The parietal peritoneum has somatic sensory innervation, typically via the nerves supplying the corresponding body wall (such as the lower intercostal, subcostal, iliohypogastric, and ilioinguinal nerves). The central diaphragmatic portion may receive fibers from the phrenic nerve. Pain from the parietal peritoneum is usually sharp and well localized.

Vascular supply and drainage: Blood supply mirrors that of the adjacent body wall, from intercostal, lumbar, and phrenic arteries, with venous drainage into the corresponding systemic veins. Lymphatic drainage follows regional abdominal wall and diaphragmatic pathways to regional lymph nodes.

Function: The parietal peritoneum provides a protective lining, participates in the production of peritoneal fluid that enables organ movement, and forms anatomical planes essential for surgical access and the organization of peritoneal reflections.