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No. 8
1. Peritoneum
Chapter 6 The
Peritoneum
Ⅰ. Introduction of Peritoneum

The peritoneum is the largest and
most complexly arranged serous
membrane in the body. It consists of
a single layer of flattened mesothelial
cells which covers a layer of loose
connective tissue. Its free surface is
extremely smooth and slippery.

Parietal peritoneum and visceral
peritoneum:
The peritoneum is situated in the
abdominal cavity and partly also in the
pelvic cavity, a part of which lines the wall
and is known as the parietal peritoneum,
while the remainder is reflected over the
contained viscera and is termed the
visceral peritoneum.
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Peritoneal cavity:
The parietal and visceral layers of the
peritoneum are in actual contact; the
potential space between them is the
peritoneal cavity which contains nothing
but a little lubricating fluid.
In the male, the peritoneal cavity is a
closed sac, in the female, it communicates
with the exterior indirectly through the
uterine tubes, uterus, and vagina.
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Functions:
The peritoneum, especially the parietal
peritoneum, has an absorptive capacity. After
abdominal and pelvic operations, it has been
customary to prop up the patient in bed so that
any inflammatory intraperitoneal effusion will
gravitate into the pelvis.
One presumed reason for adopting this position
was that the peritoneum in the subphrenic region
has a greater absorptive capacity than the other
regions; hence inflammatory products, if they
gained access to this region, would more rapidly
pass into the general circulation.
The visceral peritoneum is firmly united to the
viscera which it covers, and cannot be readily
stripped off them.
Ⅱ. The Relationship Between
Viscera and Peritoneum

According to the variable extent of
peritoneal investment, the
abdominopelvic viscera may be
categorized into following three
groups:
Ⅰ) The Intraperitoneal Viscera

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Viscera completely surrounded by
peritoneum that forms an integral
part of serous layer belong to this
group.
Such organs are stomach, jejunum,
ileum, cecum, vermiform appendix,
transverse colon, sigmoid colon,
spleen, ovaries, uterine tubes and
superior part of the duodenum.
Ⅱ) The Interperitoneal Viscera

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Such organs are not completely
wrapped by peritoneum with one
surface attached to the abdominal
walls or other organs.
Liver, gallbladder, urinary bladder,
uterus, upper part of the rectum,
ascending and descending colon are
the organs of this group.
Ⅲ) The Retroperitoneal Viscera

Some of the abdominal and pelvic
visera, such as the kidneys, ureters,
suprarenal glands, pancreas, the
middle part of rectum, the second
and inferior parts of duodenum are
retroperitoneal in position lying on
the posterior abdominal wall and
covered by peritoneum only on their
anterior aspect.
Ⅲ. The Peritoneal Reflections
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Certain terms, often arbitrary, are commonly
used for the peritoneal reflections.
A peritoneal reflection that connects the intestine
and body wall is usually named according to the
part of the gut to which it is attached.
For example, the reflection to jejunum and ileum
is termed the mesentery, that to the transverse
colon is the transverse mesocolon.
Some peritoneal reflections between organs or
between the body wall and organs, are termed
ligaments or folds. Most of such ligaments or
folds contain blood vessels. Broad peritoneal
sheets associated with stomach are termed
omenta.
Ⅰ) The Omentum

There are two omenta, the lesser
and the greater
1. The lesser omentum
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It is the fold of peritoneum which extends to the
liver from the lesser curvature of the stomach
and the commencement of the duodenum.
It is continuous with the two layers which cover
the anterorsuperior and posteroinferior surfaces
of the stomach and about the first 2 cm of the
duodenum.
The hepatogastric ligament and the
hepatoduodenal ligament:
The portion of the lesser omentum extending
between the liver and stomach is named the
hepatogastric ligament, and that between the
liver and duodenum the hepatoduodenal
ligament.
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Three key structures in the hepatoduodenal
ligament:
At the right border of the hepatoduodenal
ligament the two layers are continuous, and form
a free margin which is the anterior wall of the
epiploic foramen. In the free margin the two
layers of the hepatoduodenal ligament enclose
the proper hepatic artery, hepatic portal vein and
common bile duct (These three structures are
called three key structures in the
hepatoduodenal ligament), a few lymph nodes
and lymph vessels, and the hepatic plexus of
nerves.
The common bile duct is situated anteriorly, the
hepatic portal vein posteriorly and the proper
hepatic artery is at the left of the common bile
duct. The inferior vena cava lies behind the
epiploic foramen.
2. The greater omentum
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It is the largest peritoneal fold. It consists
of a double sheet, folded on itself so that
it is made up of four layers.
The two layers which descend from the
stomach and commencement of the
duodenum pass downwards in front of the
small intestine for a variable distance;
they then turn up on the back of itself,
and ascend to the transverse colon, where
the two layers are separated to cover the
anterior and posterior surfaces of
transverse colon. Then they form the
transverse mesocolon.
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The upper part of the greater omentum
which extends between the stomach and
the transverse colon is termed the
gastrocolic ligament.
In adult, the four layers of greater
omentum are frequently adhered together,
and are found wrapped about the organs
in the upper part of the abdomen; only
occasionally are they evenly dependent
anterior to the intestines.
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Functions:
① protective function: The greater omentum
contains numerous fixed macrophages, which
performs an important protective function.
② storehouse for fat: The greater omentum is
usually thin, and presents a cribriform
apperarance, but always contains some adipose
tissue, which in fatty people is present in
considerable quantity.
③ migration and limation: The greater omentum
may limit spread of infection in the peritoneal
cavity. Because it will migrate to the site of any
inflammation in the peritoneal cavity and wrap
itself around such a site, the greater omentum is
commonly referred to as the “policeman” of the
peritoneal cavity.
Ⅱ) The Mesenteries and
Mesocolons
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1. The mesentery (of the small intestine)
It is a broad, fan-shaped fold of
peritoneum connecting the coils of
jejunum and ileum to the posterior
abdominal wall.
The portion attached to the posterior wall
of the abdomen is called the radix (root )
of mesentery; it is about 15 cm long and
is directed obliquely downwards from the
duodenojejunal flexure (at the left side of
the second lumbar vertebra) to the upper
part of the right sacroiliac joint.
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The intestinal border of the mesentery is
about 6 m and is thrown into numerous
pleats and frills.
The mesentery consists of two layers of
the peritoneum between which lie the
jejunal and ileal branches of the superior
mesenteric artery with their accompanying
veins, nerve plexuses and lymph vessels,
the mesenteric lymph nodes, connective
tissue and fat.
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2. The mesoappendix
It is a triangular mesentery of the
vermiform appendix, and is attached to
the back of the lower end of the
mesentery of ileum, close to the ileocecal
junction.
Its layers enclose the blood vessels,
nerves and lymph vessels of the
vermiform appendix, together with a
lymph node.
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3. The transverse mesocolon
It is a broad fold which connects the
transverse colon to the anterior
border of the pancreas. Between the
layers of the transverse mesocolon
are the blood vessels, nerves and
lymphatics of the transverse colon.
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4. The sigmoid mesocolon
It is a fold of peritoneum which
attaches the sigmoid colon to the
pelvic wall.
The sigmoid and superior rectal
vessels run between the layers of the
sigmoid mesocolon, and the left
ureter descends into the pelvis
behind its apex.
Ⅲ) The Ligaments
1.
①
②
③
④
⑤
⑥
⑦
The
The
The
The
The
The
The
The
ligaments of the liver
falciform ligament of liver
ligamentum teres hepatis
coronary ligament
right triangular ligament
left triangular ligament
hepatogastric ligament
hepatoduonedenal ligament
2. The ligaments of the spleen
① The splenorenal ligament: The
splenic vessels pass between its two
layers.
② The gastrosplenic ligament:
The short gastric and left
gastroepiploic branches of the splenic
vessels run between its two layers.
3.
①
②
③
The
The
The
The
ligaments of the stomach
gastrohepatic ligament
gastrocolic ligament
gastrosplenic ligament
4. The suspensory ligament of
duodenum
Sometimes named Treitz ligament.
5. The phrenicocolic ligament
It is a fold of peritoneum which is
continued from the left colic flexure
to the diaphragm opposite the tenth
and eleventh ribs.
Ⅳ. The Peritoneal Recesses
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In certain parts of the abdomen, peritoneal fold
may bound recesses or fossae of the peritoneal
cavity.
These recesses are of surgical importance since
they may become the site of internal herniae,
that is, a piece of intestine may enter a recess
and may be constricted (strangulated) by the
peritoneal fold granding the entrance to the
recess.
From a surgical point of view the omental bursa
can be considered to belong to this category, with
its opening at the epiploic foramen, bounded in
front by the free border of the lesser omentum.
Ⅰ) The Omental Bursa

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It is a part of the peritoneal sac and
almost closed off from the remainder.
Location:
It lies behind the stomach and lesser
omentum and has a small opening,
the epiploic foramen, just above the
first part of the duodenum.
Formation:
(1) The anterior wall of the omental bursa
is formed by:
① the posterior layer of lesser omentum,
② the peritoneum which covers the
posteroinferior aspect of the stomach and
about the first 2 cm of the duodenum,
③ the posterior surface of the anterior
two layers of the greater omentum.
(2) The posterior wall is formed by:
① the anterior one of the posterior
two layers of the greater omentum
② the peritoneum which lines the
transverse colon, the transverse
mesocolon, the pancreas, the left
kidney and the left suprarenal gland.
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The upper recess of the omental burse is
roofed over by the diaphragm.
The inferior recess of the bursa is limited
by the lower border of the greater
omentum, but, as a rule, partial fusion of
the constituent layers of the greater
omentum occurs after birth, so that the
cavity of the omental bursa in the adult
does not usually extend much below the
transverse colon and its mesocolon.
(3) The omental bursa is limited to
the left by the spleen and its
peritoneal reflections, the
splenorenal and the gastrosplenic
ligaments.
(4) On the right side, the omental
bursa communicates with the greater
peritoneal sac through the epiploic
foramen.
Ⅱ) The Omental (Epiploic)
Foramen (foramen of Winslow)

Location:
It lies between the liver and
duodenum, just above the first part
of the duodenum, is a short,
vertically flattened passage, about 3
cm long, which leads out from the
upper part of the right border of the
omental bursa into the greater
peritoneal sac.
Formation:
(1) Its anterior wall is formed by the right
margin of the lesser omentum, which contains
between its two layers in this situation the
common bile duct, the hepatic portal vein and the
proper hepatic artery.
(2) The roof of the epiploic foramen is the
peritoneum covering the inferior of the caudate
lobe of the liver.
(3) Its posterior wall is the peritoneum
descending in front of the inferior vena cava.
(4) The floor of the epiploic foramen is limited by
the upper border of the superior part of the
duodenum.
Ⅲ) The Other Recesses (of much
smaller size)

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They are sometimes found in relation
to the duodenum, cecum and
sigmoid colon.
They are sometimes found in relation
to the duodenum, cecum and
sigmoid colon.
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1. Duodenal Recesses
The superior duodenal recess
The inferior duodenal recess
The paraduodenal recess
The duodenojejunal recess
2. Cecal recesses
The superior ileocecal,
The inferior ileocecal
The retrocecal recesses
The rectocolic recess
3. The intersigmoid recess
Ⅳ) Pouches

In the lesser pelvis, the peritoneum
dips downwards forming a larger
fossa, named pouch.
1. In the male
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The rectovesical pouch lies
between rectum and urinary bladder
(or the seminal vesicles and
ampullae ductus deferentes).
The rectovesical pouch is the lowest
part of the peritoneal cavity in
anatomical position in male.
2. In the female

The uterus and its broad ligaments divide
the rectovesical pouch into two pouches,
the rectouterine pouch (of Douglas)
and the vesicouterine pouch.
(1) The rectouterine pouch is formed
between the anterior surface of the
rectum and the posteriosurface of the
uterus and the upper part of vagina.
(2) The vesicouterine pouch is formed
between the anteroinferior surface of the
uterus and the posterior surface of the
urinary bladder.
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The rectouterine pouch is the lowest part
of the peritoneal cavity in anatomical
position in the female.
With a patient propped in the semi-sitting
posture, the fluid in the peritoneal cavity
may descend either to the relatively
accessible rectovesical pouch or to the
rectouterine pouch which may be
approached surgically through the rectum
or vagina.
Ⅴ. Subdivision of Peritoneal Cavity
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The greater sac is subdivided by the
greater omentum, transverse colon, and
transverse mesocolon into a
superoanterior part, the supramesocolic
compartment, and an inferoposterior
part, the inframesocolic compartment.
These compartments form channels or
recesses that determine how or where
peritoneal fluid gravitates or spreads.
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The inframesocolic compartment is further
divided by mesentery of small intestine
into right and left parts.
The latter drains into the pelvis.
The paracolic grooves are longitudinal
depressions lateral to the ascending and
descending colon.
The supramesocolic compartment is
subdivided by the liver into subphrenic
and subhepatic spaces.