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Peritoneum
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The peritoneum is a large semi translucent sheet that encapusluates the
abdominal viscera very similar to the pericardium and pleura.
 The parietal peritoneum lines the abdomino-pelvic cavity.
 The visceral peritoneum lines the organs of the abdomino-pelvic
cavity.
 Some organs begin developmentally as intraperitoneal organs, but
then are pushed to the posterior abdominal wall making them
SECONDARILY retroperitoneal.
 The stalks of peritoneum that neither cover an organ nor line the
wall of the abdomen are called the mesentery and are given special
names. Mesentary is the name given to the stalks of the small
intestine. Examples of others are transverse mesocolon,
mesosigmoid.
 The blood vessels supplying the part of the organ are in the
mesentery.
 There are NO ORGANS in the peritoneal cavity (just like the lungs
are NOT in the pleural cavity)
The greater and lesser omentum are specific types of mesentery.
 The greater omentum is broken in to three separate “ligaments”
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(areas where the peritoneum is reflected upon itself), all of which
have an attachement to the greater curvature of the stomach
o Gastrophrenic
o Gastrosplenic
o Gastrocolic (the gastrocolic houses the most anterior portion
of the lesser sac, which runs superiorly to the posterior of the
liver)
The lesser omentum is subdivided into two ligments, both of which
have an attachment to the lesser curvature of the stomach
o The hepatogastric ligament
o The hepatoduodenal ligament (the hepatoduodenal ligament
houses the common bile duct, the hepatic artery proper and
the hepatic portal vein)
The greater and lesser omentum communicate with each other
through the omental foramen, which is under the hepatoduodenal
ligament.
Peritoneal folds are created by underlying vessels (blood, lymph, remnant)
that are covered with parietal peritoneum. There are a total of five
peritoneal folds
 2-lateral folds that are associated with the inferior epigastric
arteries
 2-Medial folds that are associated with the remnant of the umbilical
artery
 1-Median fold that is associated with the remnant urachus
Fluids in the peritoneal cavity drain into two areas when a person is in the
prone position
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Hepatorenal pouch-right sided posterior to the spleen
Rectovisceral/Rectouterine pouch- in the pelvic cavity against the
sacrum
The peritoneal gutters shunt all fluids down to the rectovisceral/rectouterine
pouch. There are four named gutters: 2 paracolic and 2 infracolic
 Right and Left Paracolic. The right paracolic will drain all of the
fluids above the transverse colon (bilateral). The left will only drain
below the phrenicocolic ligament.
 Right and Left infracolic ligament. The right infracolic ligament will
either direct fluids up around the jejunum or down and over the
jejunum. It usually just stays localized.
Major Vessels
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The abdominal aorta has three major branch points prior to the bifurcation.
 The Celiac Artery
o The celiac artery first gives rise to the left gastric artery. The
left gastric artery anastomoses with the right gastric artery
which is a branch of the hepatic artery proper.
o The splenic artery is the leftward branch point of the celiac
artery. It gives rise to the pancreatic branches, the short
gastric arteries, the left gastro-omental arteries and the
posterior gastric artery.
 The pancreatic branches diverge from the splenic artery
and travel inferiorly
 The short gastric arteries branch and travel medially
toward the stomach from the distal splenic artery
 The left gastro-omental artery travels along the inferior
border of the stomach along the major curvature of the
stomach and anastomoses with the right gastroomental artery, which is a branch of the gastroduodenal
artery.
o The common hepatic vein is the right bifurcation of the celiac
artery. The common hepatic artery will then bifurcate again
to form the hepatic artery proper and the gastroduodenal
artery.
 The hepatic artery proper ascends superiorly and gives
of the right gastric artery, which anastomoses with the
left gastric artery.
 The hepatic artery proper will bifurcate to form the right
and left hepatic arteries.
 Sometimes the left hepatic artery will give off the cystic
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artery.
 The gastroduodenal artery will give off the
supraduodenal artery. The gastroduodenal artery will
then bifurcate giving rise to the superior
pancreaticoduodenal artery and the right gastroomental artery.
The Superior Mesenteric Artery
o Ateries should be identified by their targets.
The ascending colon is supplied by the right colic artery.
The transverse colon is supplied by the middle colic artery
The appendix is supplided by the iliocolic artery
The small intestine is supplied by the intestinal branches of
the superior mesenteric artery.
o The pancreas and duodenum are supplied by the inferior
pancreaticoduodenal artery.
o The inferior pancreaticoduodenal artery is the first to diverge
followed by the middle colic, right colic and iliocolic arteries.
The Inferior Mesenteric Artery
o
o
o
o

o As with the superior mesenteric artery, the branches of the
inferior mesenteric artery should be identified by the target.
o The descending colon is supplied by the left colic artery
o The sigmoid colon is supplied by the sigmoid arteries
o The medial and inferior rectum are supplied by the superior
rectal arteries
The marginal branch of Drummond is an anastomosis of all the colic
arteries that runs long the side of the large intestine and creates a
marginal branch for collateral circulation.
The portal system is the venous return from the gut.
 The Splenic vein, inferior mesenteric vein, and superior mesenteric
vein (clockwise starting in the LUQ) all drain into the portal vein,
which ends in the sinusoids of the liver.
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