The abdominal cavity, Latin cavitas abdominalis, refers to the cavity in the trunk area where the abdominal organs are located. It protects the organs and allows them to move against each other.
What is the abdominal cavity?
The abdominal cavity is one of the five cavities of the human body that serve to protect the vital organs. It is a part of the abdomen, the area between the rib cage and the pelvis, which includes the abdominal wall and abdominal organs in addition to the abdominal cavity. As the largest cavity in the body, the abdominal cavity encloses the abdominal organs, which include the stomach, large parts of the intestines, liver, gallbladder, pancreas, kidneys and spleen. The abdominal cavity is bounded cranially, i.e. upward, by the diaphragm, downward or caudally by the pelvis and pelvic floor, and anteriorly and laterally by the abdominal wall. The diaphragm closes off the thorax from the abdominal cavity, whereas there is an open connection to the pelvic cavity. In contrast to the aforementioned demarcations, which consist mainly of soft tissues, including muscle, connective tissue, and adipose tissue, the spine, iliac blades, and parts of the thorax serve as bony protection for the abdominal cavity.
Anatomy and structure
The abdominal cavity is divided into the peritoneal cavity or peritoneal cavity, Latin cavitas peritonealis, and the retroperitoneal space behind it, Latin spatium retroperitoneale. The retroperitoneal space in turn merges downward into the subperitoneal space, Latin spatium subperitoneale. The peritoneal cavity and the abdominal organs within it are covered with a serous skin, the peritoneum or peritoneum. The peritoneum is a bilayered connective tissue membrane, with a distinction made between the parietal peritoneum, which covers the peritoneal cavity, and the visceral peritoneum, which covers the abdominal organs. The parietal and visceral peritoneum, also referred to as the parietal and visceral sheets, are interconnected. The peritoneal cavity contains the so-called intraperitoneal abdominal organs. These include the stomach, spleen, liver, gallbladder, small intestine, and a substantial portion of the colon. The retroperitoneal space contains fatty tissue and connective tissue and houses the so-called retroperitoneal abdominal organs with the kidneys, adrenal glands, pancreas, and a small portion of the colon.
Function and tasks
The abdominal cavity serves as protection for the abdominal organs located within it. In addition to resisting internal hydrostatic pressure, the abdominal cavity can also resist external pressure by reflex or by its own volition. An intact abdominal cavity creates uniform pressure conditions in the abdominal region. The abdominal organs are supplied via the peritoneum, which contains numerous blood and lymph vessels and nerve pathways. The peritoneum can absorb fluid from the abdominal cavity and release it to the blood system. The peritoneum provides an airtight seal for the abdominal cavity. A connective tissue layer of the peritoneum, the tunica subserosa, serves as a suspensory ligament to support and secure the intraperitoneal organs in the appropriate position. This suspensory ligament is called the mesentery in the small intestine and the mesocolon in the large intestine. The organs stored in the abdominal cavity have various functions in digestion. The peritoneal cavity contains a clear, viscous fluid called peritoneal fluid or abdominal fluid, which covers the peritoneum. The peritoneal fluid is continually renewed and released and reabsorbed by the peritoneum, so that there are between 50 and 80 milliliters of the fluid in the abdominal cavity of a healthy person. The so-called tunica serosa, the second layer of the peritoneum, is responsible for the release of the peritoneal fluid. This fluid acts as a kind of lubricant, allowing the organs to move against each other. The mobility of the organs is important, for example, during pregnancy, a full stomach after ingestion of food, and during digestion. The peritoneal fluid has an anti-inflammatory effect and thus also serves the immune defense.
Diseases
Abdominal pain can have a wide variety of causes and can also be associated with various diseases of the abdominal cavity. Tumor diseases, for example, can occur in the peritoneum. The so-called peritoneal carcinomatosis usually occurs in the form of metastases caused by other tumor diseases.Peritonitis is an inflammation of the parietal peritoneum that occurs as a consequence of infections or tumors, for example, and is life-threatening if left untreated. It manifests as severe abdominal pain, tension of the abdominal muscles leading to a hard abdominal wall, and may present with a distended abdomen. If the stomach or intestinal wall is perforated, for example, bacteria can enter the abdominal cavity with the stomach or intestinal contents and cause peritonitis. In ascites, fluid accumulates in the abdominal cavity. This is also not a disease in its own right, but a secondary disease. Most often, cirrhosis of the liver leads to ascites, but heart failure, carcinoma and other diseases can also be the cause. Ascites is noticeable by the bulging of the abdomen and the increase in its girth. When there is bleeding into the abdominal cavity, for example, due to an injury or surgery, it is called hemascoid. In addition to abdominal pain, there is [pallor]] and poor general condition due to blood loss. In a chylaskos, lymph accumulates in the abdominal cavity; pneumoperitoneum is spoken of when gas accumulates. Pneumoperitoneum can occur as a result of injuries to the gastrointestinal tract, among other things, but it can also be deliberately induced for examination purposes, such as during a laparoscopy. Very rarely, pregnant women may experience an abdominal pregnancy in which the fertilized egg implants in the abdominal cavity instead of the uterus.