The abdominal cavity is the largest body cavity in humans and many animals, and
holds the bulk of the viscera. It is located below the thoracic cavity, and
above the pelvic cavity. Its dome-shaped roof is the thoracic diaphragm, and its
oblique floor is the pelvic inlet. It is a part of the abdominopelvic cavity. It
is well connected with the pleural cavity.
Structure = Organs =
Organs of the abdominal cavity include the stomach, liver, gallbladder, spleen,
pancreas, small intestine, kidneys, large intestine, and adrenal glands.
= Peritoneum = The abdominal cavity is lined with a
protective membrane termed the peritoneum. The inside wall is covered
by the parietal peritoneum. The kidneys are located in the abdominal cavity
behind the peritoneum, in the retroperitoneum. The viscera are also
covered by visceral peritoneum. Between the visceral and parietal
peritoneum is the peritoneal cavity, which is a potential space. It contains
serous fluid that allows motion. This motion is apparent of the
gastrointestinal tract. The peritoneum, by virtue of its connection to the two
portions, gives support to the abdominal organs.
The peritoneum divides the cavity into numerous compartments. One of these the
lesser sac is located behind the stomach and joins into the greater sac via the
foramen of Winslow. Some of the organs are attached to the walls of the abdomen
via folds of peritoneum and ligaments, such as the liver and others use broad
areas of the peritoneum, such as the pancreas. The peritoneal ligaments are
actually dense folds of the peritoneum that are used to connect viscera to
viscera or viscera to the walls of the abdomen. They are named in such a way as
to show what they connect typically. For example the gastrocolic ligament
connects the stomach and colon and the splenocolic ligament connects the spleen
and the colon, or sometimes by their shape as the round ligament or
triangular ligament. = Mesentery =
Mesenteries are folds of peritoneum that are attached to the walls of the abdomen
and enclose viscera completely. They are supplied with plentiful amounts of
blood. The three most important mesenteries are mesentery for the small
intestine, the transverse mesocolon, which attaches the back portion of the
colon to the abdominal wall, and the mesosigmoid which enfolds the sigmoid
portion of the colon. = Omenta =
The omentum are specialized folds of peritoneum that enclose nerves, blood
vessels, lymph channels, fatty tissue, and connective tissue. There are two
omenta. First, is the greater omentum that hangs off of the small intestine
and greater curvature of the stomach. The other is the lesser omentum that
extends between the stomach and the liver.
Clinical significance = Ascites =
When fluid collects in the abdominal cavity it is called ascites. This is
usually not noticeable until enough has collected to distend the abdomen. The
collection of fluid will cause pressure on the viscera, veins, and the thoracic
cavity. Treatment is directed at the cause of the fluid accumulation. One
method is to decrease the portal vein pressure, especially useful in treating
cirrhosis. Chylous ascites heals best if the lymphatic vessel involved is closed.
Heart failure can cause recurring ascites.
= Inflammation = Another disorder is called peritonitis
which usually accompanies inflammatory processes elsewhere. It can be caused by
damage to an organ, or from a contusion to the abdominal wall from the outside
or by surgery. It may be brought in by the bloodstream or the lymphatic system.
The most common origin is the gastrointestinal tract. Peritonitis can
be acute or chronic, generalized, or localized, and may be have one origin or
multiple origins. The omenta can help control the spread of infection; however
without treatment, the infection will spread throughout the cavity. An abscess
may form as a secondary reaction to an infection. Antibiotics have become an
important tool in fighting abscesses; however external drainage is usually
required also. See also
Coelom Human abdomen
Human body cavities References
External links