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Peritoneum and peritoneal cavity
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Peritoneum is a serous membrane lining the abdominopelvic cavity and
invests the viscera
o Two continuous layers – parietal and visceral, both comprising
mesothelium (simple squamous epithelium)
Parietal peritoneum is served by vessels and nerves of the body wall
o Pain is generally well localised, except for the central inferior part of
the diaphragm; innervation here is via phrenic nerve, thus pain often
referred to C3-5 dermatomes over the shoulder
Visceral peritoneum is served by vessels of the organs it overlies
o Insensitive to touch and temperature, but stimulated by stretching and
irritation
o Pain is referred to dermatomes of spinal ganglia providing the sensory
fibres
o Foregut pain experienced in epigastric region, midgut in the umbilical
region, and hindgut in the pubic region
Extraperitoneal organs are almost entirely covered by peritoneum e
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stomach and spleen
Extra peritoneal, retroperitoneal and subperitoneal are partially covered by
peritoneum
o Retroperitoneal are between the peritoneum and posterior abdominal
wall e
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kidneys
o Subperitoneal have peritoneum only on superior surface e
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bladder
Peritoneal cavity is located within the abdominal cavity and continues into
pelvic cavity; contains peritoneal fluid (H2O, electrolytes, other substances
from interstitial fluid, leukocytes, antibodies)
o Lubrication, allowing organs to move over one another
Lymphatic vessels absorb the peritoneal fluid
Peritoneal cavity is closed in males but open in females via the uterine tubes

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Embryology of the peritoneal cavity
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When initially formed, the gut is the same length as the developing body
Undergoes large growth by the 10th week of development; growth is enabled
by development outside of the anterior body wall
Early in development, the embryonic body cavity (intraembryonic coelom) is
lined with mesoderm
At a later stage, the abdominal cavity is lined with parietal peritoneum,
forming a closed sac
As the organs develop, they protrude into the peritoneal sac, acquiring a
covering (visceral peritoneum)
Viscera are connected to the abdominal wall by mesentery of variable
length; composed of two layers of peritoneum with connective tissue inbetween
As organs protrude into the peritoneum, their vessels, nerves and lymphatics
remain connected to their extraperitoneal sources, lying between the
peritoneum layers forming the mesenteries
As the organs grow, they reduce the size of the peritoneal cavity; thus several
parts of the gut come to lie on the posterior abdominal wall
Descending and ascending colon start off intraperitoneal and become
secondary retroperitoneal; layers of peritoneum fuse to form a fusion fascia
o Nerves and vessels lie in the fascia
Many parts of the GI tract and associated organs become secondary
retroperitoneal – most of duodenum, pancreas, ascending and descending
colon

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Peritoneal formations
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Peritoneal cavity has a complex shape; highly convoluted as has a surface
area greater than the skin
Mesentery is a double layer of peritoneum with a core of connective tissue
that occurs as a result of the invagination of the peritoneum by an organ
o Provides means of neurovascular communication between organ and
body wall
Omentum is a prominent, four layered peritoneal fold
Greater omentum hangs down from the greater curvature of the stomach
and proximal duodenum; folds back to attach to the anterior transverse
colon and its mesentery
Lesser omentum connects the lesser curvature of the stomach and proximal
duodenum to the liver
Peritoneal ligament is a double layer of peritoneum connecting an organ
with another organ or to the abdominal wall
The liver connects to
o Anterior abdominal wall (falciform ligament)
o Stomach (hypogastric ligament)
o Duodenum (hepatoduodenal ligament; conducts the portal triad)
Hypogastric and hepatoduodenal ligaments are continuous parts of the
lesser omentum
The stomach connects to
o Inferior surface of the diaphragm (gastrophrenic ligament)
o Spleen (gastrosplenic ligament)
o Transverse colon (gastrocoelic ligament)
Bare areas are the areas of the organ not covered by peritoneum, where
neurovascular structures enter and exit
Peritoneal fold is a reflection of peritoneum from the body wall by underlying
vessels, ducts, and ligaments formed from obliterated foetal vessels e
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umbilical folds; some contain blood vessels
A peritoneal recess/fossa is a pouch of peritoneum formed by a peritoneal
fold

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Subdivisions of the peritoneal cavity
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Peritoneal cavity is divided into the greater and lesser peritoneal sacs
Greater sac is the main and larger part
Omental bursa (lesser sac) lies posterior to the stomach and lesser omentum
Transverse mesocolon (mesentery of the transverse colon) divides the
abdominal cavity into
o Supracolic compartment – contains liver, stomach, spleen
o Infracolic compartment – small intestine, ascending and descending
colon
Infracolic compartment lies posterior to the greater omentum and divided
into the right and left infracolic flexures by mesentery of the small intestine
Paracolic gutters are grooves between the colon and posterolateral
abdominal wall that allow communication between thee supracolic and
infracolic compartments
Omental bursa has a superior recess and inferior recess
Omental bursa allows free movement of the stomach on posterior and inferior
structures
Omental bursa communicates with the greater sac via the omental foramen,
an opening located posterior to the free edge of the lesser omentum
(heptoduodernal ligament)
Boundaries of the omental foramen
o Anterior: hepatoduodenal ligament (containing hepatic portal vein,
hepatic artery, bile duct
o Posterior: IVC, right crus of the diaphragm (muscular band)
o Superior: liver
o Inferior: superior part of duodenum

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Taken from Moore et al, Clinically Oriented Anatomy, Seventh Edition

Medical application
Patency of uterine tubes
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Primary mechanism in preventing peritoneal infection is the mucous
plug that blocks the external os
Patency of uterine tubes can be tested clinically by
hystersalpingography, with air or radiopaque dye is injected into the
uterine cavity

Peritonitis and ascites
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Infection and inflammation of the peritoneum can occur from
bacterial contamination during laparotomy, trauma
Severe pain in overlying skin
Peritonitis can become generalised (spread over wide area)
Tenderness, nausea, vomiting and fever may also occur
Patients often lie with knees flexed to relax anterolateral abdominal
muscles to reduce intense pain; also take shallow breaths to prevent
increasing intra-abdominal pressure and thus pain too much
Excess fluid in the peritoneal cavity is called ascetic fluid (ascites)
May occur due to perforated stomach or duodenal ulcer, or
mechanical injury, portal hypertension, metastasis, starvation
Peritoneal cavity may be distended with several litres of fluid,
preventing visceral movement
Treatment by removal of ascetic fluid and large doses of antibiotic if
infection present
Localised accumulations may need to be aspirated/drained by
paracentesis (surgical puncture of peritoneal cavity and cannula)

Peritoneal adhesions
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Damage or infection of the peritoneum can cause inflammation
As healing occurs, fibrin may be replaced with fibrous tissue, forming
abnormal attachments between visceral peritoneum of adjacent
viscera or the posterior abdominal wall
Adhesions can limit normal visceral movement, causing chronic pain
or complications such as intestinal obstruction (becomes twisted
around the adhesion; volvulus)
Adhesiotomy is the surgical separation of adhesions

Intraperitoneal injections and peritoneal dialysis
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Fluid injected into peritoneal cavity is rapidly absorbed
Anaesthetic agents can be injected by intraperitoneal injection
In renal failure, waste products such as urea can accumulate in
blood and tissues

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Peritoneal dialysis allows removal of soluble substrates and excess fluids
by transfer across the peritoneum, using dilute sterile solution
Temporary measure; renal dialysis required long-term

Functions of greater omentum
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Prevents visceral peritoneum from adhering to the parietal peritoneum
Mobile
Can form adhesions to adjacent organs
Cushions abdominal organs against injury and insulation against loss of
body heat

Abscess formation
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Abscess is a circumscribed collection of purulent exudate (pus)
Cam form in the subphrenic recess by perforation of a duodenal ulcer,
gallbladder ulcer, appendix perforation

Spread of pathological fluid
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Peritoneal recess are clinically important in the spread of pathological
fluids
Recess determines extent and direction of spread of fluids

Flow of ascetic fluid and pus
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Paracolic gutters are clinically important as they provide a pathway for
flow of ascetic fluid and spread of intraperitoneal infections
Purulent material can be transported along the paracolic gutters into
the pelvis, when patient is upright
Purulent material can travel to the subphrenic recess under the
diaphragm when patient is supine

Fluid in omental bursa
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Fluid in the bursa can result in a pancreatic pseudocyst
Caused by perforation of stomach or inflamed pancreas

Intestine in omental bursa
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Loop of small intestine may pass through the omental foramen and be
strangulated
Boundaries of the foramen cannot be excised as they contain blood
vessels, so intestine must be decompressed and returned through

Severance of cystic artery
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During removal of the gallbladder (cholecystectomy), the cystic
artery must be ligated/clamped
Accidental severance of the artery can occur
Can be compressed against the hepatoduodenal ligament



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