The Peritoneum and Peritoneal
Cavity
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Inguinal region | Main Anatomy Index | Oesophagus
Last updated 30 March 2006
The Peritoneum and the Peritoneal Cavity
- The peritoneum is a thin, transparent serous membrane
that consists of two layers.
- The peritoneum lining the abdominal wall is called the parietal
peritoneum.
- The peritoneum investing the viscera is called the visceral
peritoneum.
- Both types of peritoneum consist of a single layer of squamous epithelium (mesothelium).
- The parietal and visceral layers of peritoneum are separated from each other by capillary films of peritoneal fluid.
- This serous fluid lubricates the peritoneal surfaces, enabling the viscera to move on
each other without friction.
- When an organ protrudes into the peritoneal sac, it takes its
vessels and nerves with it.
- They are located between to two layers of peritoneum and form the mesentery.
- There is also loose connective tissue between these layers that contains a variable
amount of fat cells.
- Viscera with mesentery are mobile, the degree to which
depends on the length of mesentery.
- As the developing organs enlarge, they obliterate the peritoneal
cavity almost completely.
- As the foetal organs assume their adult positions, the peritoneal
cavity is divided into two peritoneal sacs, the greater
and lesser sacs of the peritoneum.
- A surgical incision through the anterior abdominal wall enters
the greater peritoneal sac.
- The lesser sac, known as the omental bursa, lies posterior to the stomach, lesser
omentum and liver.
- The peritoneal cavity is closed in males.
- In females, there is a communication with the exterior through the uterine tubes, uterus
and vagina.
Descriptive Terms
Mesentery
- This is a double layer of peritoneum that encloses the
organ and connects it to the abdominal wall.
- Mesenteries have a core of loose connective tissue
containing a variable number of fat cells and lymph nodes along with nerves and vessels
passing to and from the viscera.
- The mesentery of the stomach is called the mesogastrium
(G. gaster, stomach).
- The mesentery of the transverse colon is the transverse mesocolon.
- The mesentery of the small intestine is the mesentery.
- Some visceral have no mesentery and are extraperitoneal or retroperitoneal
(e.g., the ascending colon and kidneys).
- These organs lie on the posterior
abdominal wall and are covered by peritoneum anteriorly.
- The liver develops in the ventral mesogastrium.
- The spleen develops in the dorsal mesogastrium.
Omentum
- This is a double-layered sheet or fold of peritoneum.
- The lesser and greater omentum attach the stomach to the body wall or to other abdominal
organs.
The Lesser Omentum
- This fold of peritoneum connects the lesser curvature of the
stomach and the proximal part of the duodenum
to the liver.
- Individually, these connections are referred to as the gastrohepatic
ligament and the hepatoduodenal ligament.
- The lesser omentum lies posterior to the left lobe of the liver
and is attached to the liver in the fissure for the ligamentum
venosum.
- It is also attached to the porta hepatis, the
transverse fissure or gate (L. porta) on the inferior surface of the liver through
which the bile duct, vessels, and nerves enter or leave the liver.
The Greater Omentum
- This is a fat-laden fold of peritoneum that hangs down from the greater
curvature of the stomach and connects the stomach with the diaphragm,
spleen, and transverse colon.
- This double-layered peritoneal fold normally fuses during the foetal period, thereby obliterating the inferior recess of the omental bursa.
- As a result, the apron-like greater omentum is composed of four
layers of peritoneum.
- After passing inferiorly as far as the pelvis, the greater omentum loops
back on itself, overlying and attaching to the transverse
colon.
Peritoneal Ligaments
- A peritoneal ligament is a double layer of peritoneum
that connects an organ with another organ or with the abdominal wall.
- Ligaments may contain blood vessels or remnants of vessels (e.g., the falciform ligament
contains the ligamentum teres, a remnant of the foetal umbilical vein).
- The greater omentum is divided into 3 parts:
- The apron-like part, called the gastrocolic ligament,
is attached to the transverse colon.
- The left part, called the gastrosplenic ligament
(gastrolienal ligament), connects the hilum of the spleen to the greater curvature and
fundus of the stomach.
- The superior part called the gastrophrenic ligament is
attached to the diaphragm and the posterior aspect of the fundus and the oesophagus.
- The falciform ligament extends from the liver to the anterior abdominal wall and the
diaphragm.
- The ligamentum teres is the obliterated remnant of the left umbilical vein, lying in the free edge of the falciform
ligament and extending from the groove for the ligamentum teres to the umbilicus.
- The superior (anterior) and inferior (posterior) layers of the
coronary ligament are reflections of the peritoneum, which surround the bare
area of the liver.
- The left and right triangular ligaments are where the
layers of the coronary ligament meet to the left and right respectively.
- The falciform, coronary and triangular ligaments are derived from
that part of the ventral mesogastrium connecting the liver to the
body wall.
- The gastrohepatic and hepatoduodenal ligaments are derived from
that part of the ventral mesogastrium connecting the stomach and the
liver.
- The gastrosplenic and gastrophrenic, as well as the lienorenal and phrenicolienal
ligaments are derived from the dorsal mesogastrium.
The Peritoneal Folds
- A peritoneal fold (L. plica) is a reflection of peritoneum with more or less
sharp borders.
- Often it is formed by peritoneum that covers blood vessels, ducts, and obliterated
foetal vessels.
- The median umbilical fold contains the urachus, which extends from the urinary bladder to the
umbilicus.
- The medial umbilical folds are raised by the
obliterated umbilical arteries, extending from the internal iliac arteries to the
umbilicus.
- The lateral umbilical folds are raised by the inferior
epigastric arteries, extending from the deep inguinal rings on each side to the arcuate
lines.
Peritoneal Pouches
- The rectouterine pouch (in females) separating the
rectus from the bladder.
- The rectovesical pouch (in males) separating the rectum
from the bladder.
- The vesicounterine pouch (in females) separating the
bladder from the uterus.
Blood Supply of the
Peritoneum
To the parietal peritoneum
- Lumbar vessels
- Branches of the inferior and superior epigastric arteries
- Musculophrenic artery
- Deep circumflex arteries
To the visceral peritoneum
- From the arteries supplying the appropriate viscera
Nerve Supply to the
Peritoneum
To the parietal peritoneum
- From the nerves supplying the adjacent body wall and diaphragm
To the visceral peritoneum
- Sympathetic nerves innervating the appropriate visceral
The receptors are sensitive to:
- Overdistension of the hollow viscera
- Traction on the mesenteries which stretch the nerve plexus in the wall of the organ or
mesentery
- Spasm of smooth muscle
- Ischæmia (inadequate blood supply)
Subdivisions
of the Peritoneal Cavity
- The greater omentum, along with the transverse
colon and the transverse mesocolon, forms a
shelf that subdivides the peritoneal cavity into supracolic
and infracolic compartments.
The Omental Bursa
- The omental bursa (lesser sac of the peritoneum) is the large compartment or recess of
the peritoneal cavity that is located between the stomach
and the posterior abdominal wall.
- The omental bursa is also located posterior to the lesser
omentum and stomach.
- The anterior and posterior walls of the bursa slide freely
during contraction and distension of the stomach, giving it
considerable freedom.
- The inferior extension of the omental bursa is called the inferior
recess.
- It is the duplicated layers of the gastrocolic ligament
of the greater omentum.
- In adults, the inferior recess of the omental bursa is a potential space.
- It is usually shut off from the rest of the bursa owing to
adhesion of the layers of the gastrocolic ligament.
- The omental bursa also has a superior recess.
- This is limited superiorly by the diaphragm
and the posterior layers of the coronary ligament.
- The omental bursa is in communication with the main peritoneal cavity through the omental foramen (epiploic foramen or foramen of Winslow).
- This is located posterior to the free edge of the lesser omentum.
- The omental foramen is usually large enough to admit two digits.
Boundaries of the Omental Foramen
- Anteriorly: the portal vein, hepatic artery, and bile
duct (all in the free edge of the lesser omentum).
- Posteriorly: the inferior vena cava and right crus of
the diaphragm.
- Superiorly: the caudate lobe of the liver.
- Inferiorly: the superior part of the duodenum, portal
vein, hepatic artery and bile duct.