Its dome-shaped roof is the thoracic diaphragm, a thin sheet of muscle under the lungs, and its floor is the pelvic inlet, opening into the pelvis.

[1] The abdominal cavity is lined with a protective membrane termed the peritoneum.

The peritoneum, by virtue of its connection to the two (parietal and visceral) portions, gives support to the abdominal organs.

[1] Mesenteries are folds of peritoneum that are attached to the walls of the abdomen and enclose viscera completely.

The three most important mesenteries are mesentery for the small intestine, the transverse mesocolon, which attaches the back portion of the colon to the abdominal wall, and the sigmoid mesocolon which enfolds the sigmoid colon.

[1] When fluid collects in the abdominal cavity, this condition is called ascites.

The collection of fluid will cause pressure on the viscera, veins, and thoracic cavity.

Antibiotics have become an important tool in fighting abscesses; however, external drainage is usually required also.