Abdominal cavity

The abdominal cavity is a large space within the body. It houses many vital organs in humans and other animals. This space is part of a larger area called the abdominopelvic cavity. It is located directly below the thoracic cavity, which is your chest area. It sits above the pelvic cavity. The roof of this cavity is the thoracic diaphragm. This is a thin sheet of muscle found under the lungs. The floor of the cavity is the pelvic inlet. This opening leads into the pelvis.

A protective membrane called the peritoneum lines the entire abdominal cavity. This membrane has two distinct parts that work together. The parietal peritoneum covers the inside wall of the cavity. The visceral peritoneum covers the organs, known as the viscera. A small space exists between these two layers. This is called the peritoneal cavity. It is considered a potential space. It contains a serous fluid called peritoneal fluid. This fluid allows for smooth motion. This motion is especially important for the gastrointestinal tract. The peritoneum also provides structural support to the abdominal organs.

The peritoneum creates many different compartments and connections. Some organs are attached to the abdominal walls via ligaments. These are dense folds of the peritoneum. They connect viscera to other viscera or to the walls. Their names often describe what they connect. For example, the gastrocolic ligament connects the stomach and the colon. The splenocolic ligament connects the spleen and the colon. Some ligaments are named for their shapes, like the round or triangular ligaments. Other organs use broad areas of the peritoneum for attachment. The pancreas is a good example of this.

Other specialized folds are called mesenteries. These folds attach to the abdominal walls and enclose the viscera completely. They are supplied with plentiful amounts of blood. There are three very important mesenteries to know. One is the mesentery for the small intestine. Another is the transverse mesocolon, which attaches the back of the colon to the wall. The third is the sigmoid mesocolon, which enfolds the sigmoid colon. There are also two types of omenta. The greater omentum hangs from the transverse colon and the stomach. The lesser omentum extends between the stomach and the liver. These omenta enclose nerves, blood vessels, and fatty tissue.

Inside this cavity, many specific organs reside. These include the stomach and the liver. The gallbladder and the spleen are also located here. You will find the pancreas and the small intestine. The large intestine is another major part of the cavity. The kidneys and the adrenal glands are also included. However, the kidneys are positioned in a special way. They are located behind the peritoneum. This specific area is called the retroperitoneum. This means the kidneys sit outside the main abdominal cavity.

Sometimes, medical issues can arise within this space. One condition is called ascites. This happens when fluid collects in the abdominal cavity. It may not be noticeable until the abdomen distends. This fluid can cause pressure on the viscera, veins, and thoracic cavity. Doctors treat ascites by addressing the cause of the fluid. For example, they may try to decrease portal vein pressure. This is useful when treating cirrhosis. In cases of chylous ascites, healing is best if the lymphatic vessel is closed. Heart failure can also cause recurring ascites.

Another serious condition is peritonitis. This is an inflammation of the peritoneum. It often accompanies inflammatory processes elsewhere in the body. It can be caused by organ damage or a contusion to the wall. Surgery can also lead to peritonitis. The infection can arrive through the bloodstream or lymphatic system. The gastrointestinal tract is the most common origin. Peritonitis can be acute or chronic. It can also be localized or generalized. The omenta can help control the spread of infection. However, without treatment, the infection can spread throughout the cavity. An abscess, or a pocket of infection, may form as a secondary reaction. Doctors use antibiotics and sometimes external drainage to fight abscesses.