The liver is the largest organ in the abdominal cavity.
Kidneys are retroperitoneal and so lie between the peritoneum and the abdominal wall, in the retroperitoneal space (a part of the abdominal cavity).
The retroperitoneal cavity is located immediately posterior to the abdominal cavity (behind). It contains the kidneys (and so also the adrenal glands), the pancreas, and the abdominal aorta and vena cava. The walls of the abdominal cavity are covered with a serous membrane, called the peritoneum, as are most internal organs. The fluid in the membrane protects these structures and reduces friction between the organs and the cavity walls as well as between the organs themselves. The retroperitoneal space is separated from the peritoneal space by this layer of membrane covering the anterior organs e.g. liver, stomach, intestines. Both spaces are within the abdominal cavity.
there is no 'empty' space in the abdomen (abdominal cavity) because all the organs fit nice and snug and whatever space is left is filled with fluid.
Matter does.
Volume is the space. period.
The peritoneal cavity is the space between the visceral and parietal peritoneum in the abdominal cavity.
The kidneys lie behind the abdominal cavity in the retroperitoneal space. This anatomical space actually contains no structures.
Abdominal cavity
Kidneys are retroperitoneal and so lie between the peritoneum and the abdominal wall, in the retroperitoneal space (a part of the abdominal cavity).
They are located at the rear of the abdominal cavity in the retroperitoneal space,
The retroperitoneal space contains organs in the abdominal cavity that are behind the peritoneal lining.
The Thoracic cavity (above the diaphragm) & the Abdominal cavity (below).
Tightening of the diaphragm.
abdominal cavity
The abdominal cavity contains most of the digestive organs whereas the peritoneal cavity is the space between the parietal and visceral layers.
The retroperitoneal cavity is located immediately posterior to the abdominal cavity (behind). It contains the kidneys (and so also the adrenal glands), the pancreas, and the abdominal aorta and vena cava. The walls of the abdominal cavity are covered with a serous membrane, called the peritoneum, as are most internal organs. The fluid in the membrane protects these structures and reduces friction between the organs and the cavity walls as well as between the organs themselves. The retroperitoneal space is separated from the peritoneal space by this layer of membrane covering the anterior organs e.g. liver, stomach, intestines. Both spaces are within the abdominal cavity.
The peritoneum ( /ˌpɛrɨtənˈiəm/) is the serous membrane that forms the lining of the abdominal cavity or the coelom-it covers most of the intra-abdominal (or coelomic) organs-inamniotes and some invertebrates (annelids, for instance). It is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum both supports the abdominal organs and serves as a conduit for their blood and lymph vessels and nerves.The abdominal cavity (the space bounded by the vertebrae, abdominal muscles, diaphragm and pelvic floor) should not be confused with the intraperitoneal space (located within the abdominal cavity, but wrapped in peritoneum). The structures within the intraperitoneal space are called "intraperitoneal" (e.g. the stomach), the structures in the abdominal cavity that are located behind the intraperitoneal space are called "retroperitoneal" (e.g. the kidneys), and those structures below the intraperitoneal space are called "subperitoneal" or "infraperitoneal" (e.g. the bladder).