Abdominal cavity and peritoneum:
The abdominal cavity is the largest hollow space of the body. Its upper boundary is the diaphragm, a sheet of muscle and connective tissue that separates it from the chest cavity; its lower boundary is the upper plane of the pelvic cavity. Vertically it is enclosed by the vertebral column and the abdominal and other muscles.
The abdominal cavity contains the greater part of the digestive tract (stomach, the small and large intestines), the liver and pancreas, the spleen, the kidneys, and the adrenal glands located above the kidneys. Below it is continuous with the pevic cavity which contains the urinary bladder, the prostate, uterus and vagina and the rectum( terminal part of the large intestine)
The abdominal cavity is lined by the peritoneum, a membrane that covers not only the inside wall of the cavity (parietal peritoneum) but also every organ or structure contained in it (visceral peritoneum). Its surface is as large as the skin surface, 2 square meters.
The space between the visceral and parietal peritoneum, the peritoneal cavity, normally contains a small amount of serous fluid that permits free movement of the viscera (organs), particularly of the intestines, inside the peritoneal cavity.