THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -abdominal cavity, 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.

Detailed explanation-2: -Your peritoneum is a membrane that lines the inside of your abdomen and pelvis (parietal layer). It also covers many of your organs inside (visceral layer). The space in between these layers is called your peritoneal cavity.