Abstract
The peritoneal cavity (cavum peritonei) is incompletely divided into spaces and recessus (or fossae), which are playing an important role in health and disease. Peritoneal subspaces are determined by the parietal attachments of the abdominal organs, the ligaments and mesenteries. These include the splenorenal, the falciform, the triangular, the gastrosplenic, the phrenicocolic and the gastrocolic ligaments; the greater omentum and the lesser omentum (formed by the gastrohepatic and hepatoduodenal ligaments); the small bowel mesenterium and the mesocolon. These ligaments and mesenteries divide the peritoneal cavity into several distinct anatomic and functional regions. The supramesocolic compartment is divided into a bilateral subphrenic space and a subhepatic space continuing into the lesser sac (bursa omentalis). The inframesolic compartment is divided into a left and right region by the mesentery. The right paracolic gutter communicates with the pelvis and with the right suphrenic space. The left paracolic gutter is separated from the left subphrenic space by the phrenocolic ligament. The peritoneal space is virtual, is completely occupied by the intraabdominal organs and can only be visualized by radiological means in the presence of air (organ perforation), liquid (ascites, pus, bile, gastrointestinal fluids) or tumor invasion. Peritoneal morphology has numerous pathophysiological implications: it impacts on the propagation of intraabdominal infections, determines the spreading of peritoneal metastasis and can cause bowel volvulus. Internal hernias can arise at the junction between intraperitoneal and extraperitoneal bowel segments, in particular into the left paraduodenal recessus. Knowledge of peritoneal morphology is a precondition for developing locoregional therapeutic strategies in peritoneal disease and for effective peritoneal dialysis.