The largest serous membrane in the body, with a surface area comparable to that of the skin, lining the abdomen and pelvis
Peritoneum — parietal and visceral layers.
Anatomy · Organs & viscera
Peritoneum
The largest serous membrane in the body
Abdomen and pelvis · serous membrane
The peritoneum is the thin, glistening serous membrane that lines the abdominal and pelvic cavities and drapes over most of the organs within them. Its parietal layer lines the wall and its visceral layer covers the organs, enclosing a potential space, the peritoneal cavity, that holds only a film of lubricating fluid. Folds of peritoneum form the mesenteries, omenta and ligaments that suspend and connect the organs and carry their vessels and nerves.
How to spot them
- ▸A smooth, shiny, transparent membrane with a parietal layer on the wall and a visceral layer on the organs
- ▸Organs are either intraperitoneal (almost wholly covered, on a mesentery) or retroperitoneal (covered only on the front)
- ▸Folds include the greater and lesser omenta, the mesenteries of the small bowel and the transverse and sigmoid mesocolons
- ▸Pouches include the hepatorenal pouch (of Morison), the rectouterine pouch (of Douglas) and the rectovesical pouch
What to know
The apron of double-layered fat-laden folds that hangs down from the stomach in front of the small bowel, sometimes called the 'policeman of the abdomen'
The greater omentum, a fold of peritoneum.
The fan-shaped double fold that suspends the small intestine and carries its vessels, attached along a 15 cm root from the left of L2 to the right sacroiliac joint
The mesentery — a fold of peritoneum.
The space behind the stomach connected to the main cavity by a small opening behind the hepatoduodenal ligament, named after a Danish-French anatomist
The lesser sac (omental bursa), reached by the epiploic foramen of Winslow.
The lowest part of the female abdominal cavity, between the uterus and the rectum, where fluid or pus collects when lying or sitting upright
The pouch of Douglas (rectouterine pouch).
The mnemonic 'SAD PUCKER' lists structures that lie behind it, such as the pancreas, kidneys, ureters and duodenum
The retroperitoneal organs — behind the peritoneum.
Fluid collecting in its cavity in cirrhosis, giving a swollen abdomen, or inflammation of it causing a rigid board-like belly
Ascites in the peritoneal cavity, and peritonitis.
In a woman it is open to the exterior through the fallopian tubes, but in a man it is a closed sac
The peritoneal cavity — continuous with the outside through the uterine tubes in women.
Key ideas
- Because the peritoneum has a rich blood and lymph supply and a large surface, it can absorb fluid and drugs quickly, which is the basis of peritoneal dialysis for kidney failure.
- The parietal peritoneum has somatic nerve supply and gives sharp, well-localised pain; the visceral peritoneum has autonomic supply and gives dull, poorly localised pain.
Quick-fire facts
- •It is a single continuous sheet of mesothelium on connective tissue, forming a closed sac in males and communicating with the exterior via the uterine tubes in females.
- •The peritoneal cavity normally holds only a thin film of fluid, typically less than 100 mL.
- •Its surface area is about 1.8 square metres, similar to that of the skin.
- •Retroperitoneal organs: suprarenal glands, aorta and IVC, duodenum (2nd to 4th parts), pancreas (except the tail), ureters, ascending and descending colon, kidneys, oesophagus and rectum (lower part).
- •The hepatorenal pouch (Morison's pouch) is the most dependent part of the peritoneal cavity in the supine patient, so free fluid collects there.
- •The epiploic foramen (of Winslow) is the only communication between the greater and lesser sacs.
- •In peritonitis, movement causes pain, and the abdominal wall may become 'board-like' with guarding and rebound tenderness.
- •In peritoneal dialysis, dialysate is run into the peritoneal cavity through a catheter, and the membrane acts as the filter.
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Sources
- TeachMeAnatomy — The Peritoneum
- OpenStax — Overview of the Digestive System (Anatomy and Physiology 2e, section 23.1)