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Peritoneum and Peritoneal Cavity


Peritoneum is the largest serous membrane composed of mesothelial cells (simple squamous epithelium. It is divisible into parietal and visceral layers.

  1. Parietal peritoneum: - It lines the abdominal and pelvic walls and inferior surface of diaphragm. It develops from somatopleuric mesoderm. Its blood and nerve supplies are same as those of overlying body wall. Because of somatic innervation, parietal peritoneum is pain sensitive.
  2. Visceral peritoneum: - It is continuous mesothelial serous membrane which covers outer surface of abdominal and pelvic viscera, forming the outermost serous coat. It develops from splanchnopleuric mesoderm, its blood and nerve supplies are same as those of underlying viscera (i.e. autonomic nerves). Visceral peritoneum is relatively insensitive to pain, however because of autonomic innervation; visceral peritoneum evokes pain when the viscera is stretched, ischemic or distended.

Peritoneal Folds

A number of double layered peritoneal folds suspend some of the abdominal organs to the walls. If the visceral organ is covered with peritoneum from all side, it is called intraperitonealwhich may be completely covered with peritoneum (complete intraperitoneal) or partially covered. Intraperitoneal organs are mobile. Some organs rest on posterior abdominal wall and are covered with peritoneum on one side and therefore known as retroperitoneal organs. Retroperitoneal organs are fixed and immobile. Pelvic organs are below the reflections of peritoneum and are called subperitoneal organs.


Relation to peritoneum



Complete intraperitoneal
Partially covered


Stomach, jejunum, ileum, caecum, appendix

Ascending colon, descending colon, rectum


Duodenum, pancreas, kidney, ureter, suprarenal gland


Urinary bladder, prostate, seminal vesicle, cervix, vagina


Peritoneal folds serve as pathways for neurovascular structures to reach the organs from abdominal wall.


Peritoneal fold


Greater omentum


Lesser omentum

Right free margin

Along lesser curvature




Transverse mesocolon


Sigmoid mesocolon

Right and left gastroepiploic vessels



Hepatic artery, portal vein, bile duct
Right and left gastric vessels


Jejunal and ileal branches of superior mesenteric artery

Middle colic vessels


Sigmoid and superior rectal vessels


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Name of the peritoneal fold may be as follows:-

  1. Peritoneal folds attached to stomach are called omenta:-Lesser omentum and greater omentum.
  2. Peritoneal fold suspending intestine is called mesentery. Mesentery of small intestine (jejunum and ileum) is called mesentery proper (generally referred as mesentery) and mesentery of large intestine (colon) is called mesocolon.
  3. Folds of peritoneum connecting organs to each other or to abdominal wall are called ligaments, e.g. linorenal ligament and gastrosplenic ligament.


  1. Greater omentum: - It is a large 4 layered peritoneal fold hanging down like an apron from greater curvature.
    Anterior two layers descend from greater curvature of stomach to a variable extent, and fold upon themselves to form posterior two layers, i.e. first layer becomes the fourth layer and second layer becomes third layer. The part of the peritoneal cavity called lesser sac between 2nd and 3rd layers gets obliterated, except for about 2.5 cm below the greater curvature of stomach. Greater omentum contains the right and left gastroepiploic vessels which anastomose with each other in the interval between the first two layers. Greater omentum acts as storehouse of fat. Greater omentum is generally referred to as "policeman of abdomen because it adheres to areas of inflammation, wrapping around the inflamed organs, localizing the infections and preventing serious diffuse peritonitis. It develops from caudal part of dorsal mesogastrium.
  2. Lesser omentum: - It extends from liver to stomach (lesser curvature) and duodenum (first 2 cm). The part of lesseromentum from liver to stomach is called hepatogastric ligament, and part from liver to duodenum is called hepatoduodenal ligament. Hepatogastric ligament forms anterior free wall of lesser sac (omental bursa) and contains right and left gastric vessels, branches of gastric nerves and lymph vessels. Hepatoduodenal ligament forms right free margin, contains portal vein, hepatic artery proper, bile duct, lymphatics and hepatic plexus of nerves. Lesser omentum develops from ventral mesogastrium (dorsal part).


  1. Mesentery proper: - Mesentery of small intestine (jejunum and ileum) is fan shaped double layered peritoneal fold which suspends the coils of jejunum and ileum. Mesentery has :-
    1. Attached border (root of mesentery):- It is 15 cm long and extends from duodenojejunal flexure to upper part of right sacroiliac joint. Root of mesentery crosses following structures: -
      1. 3rd part (horizontal part) of duodenum,
      2. abdominal aorta
      3. IVC,
      4. right ureter and
      5. right psoas major.
    2. Free border (intestinal border):- It is 6 meters long and is attached to gut forming its visceral peritoneum (serous coat).
      Contents of mesentery are: -
      1. Jejunal and ileal branches of superior mesenteric vessels;
      2. Autonomic nerve plexuses;
      3. Lymphatics and lymph nodes and
      4. Connective tissue with fat.
  2. Transverse mesocolon: - It connects transverse colon to posterior abdominal wall and contains middle colic vessels.
  3. Mesoappendix: - It connects the appendix to the ileal mesentery and contains appendicular vessels.
  4. Sigmoid mesocolon: - It connects sigmoid colon to posterior pelvic wall and contains sigmoid vessels.

Peritoneal ligaments

  1. Gastrosplenic ligament: - It extends from hilum of spleen to greater curvature of stomach. It contains short gastric and left gastroepiploic vessels. It develops from dorsal mesogastrium.
  2. Linorenal ligament: - It extends from hilum of spleen to anterior surface of left kidney. It contains splenic vessels and tail of pancreas. It develops from dorsal mesogastrium.
  3. Gastrophrenic ligament:-It connects the greater curvature of stomach to diaphragm. It develops from dorsal mesogastrium.
  4. Phrenicocolic ligament: - It connects left colic (splenic) flexure to diaphragm. It supports the anterior border of spleen.
  5. Falciform ligament: - It is a sickle shaped peritoneal fold connecting anterosuperior surface of liver to anterior abdominal wall and diaphragm. It demarcates the right and left lobes of liver. It contains ligamentum teres (remnant of left umbilical vein) and paraumblical vein. It develops of ventral mesogastrium (ventral part).
  6. Coronary ligaments: - It contains superior and inferior layers which connect liver to diaphragm, and encloses the triangular 'bare area of liver'. It develops from ventral mesogastrium.
Triangular ligaments (a right and a left):- These connect right and left lobes of liver to diaphragm. It develops from ventral mesogastrium.

Peritoneal Cavity

Peritoneal cavity is the potential space between parietal and visceral layers and is filled with serous peritoneal fluid.


Peritoneal cavity is broadly subdivided into lesser sac and greater sac.


Lesser Sac (omental bursa)

  1. Lesser sac is also called omental bursa or left sub hepatic space or left posterior intraperitoneal space. It is a deep peritoneal space lying behind the stomach, lesser omentum and liver (caudate lobe). It is a closed space except for its communication on right side with greater sac through epiploic foramen.
  2. Boundaries of lesser sac are :-
    1. Anterior wall: - Caudate lobe of liver, stomach, lesser omentum and 2nd layer of greater omentum.
    2. Posterior wall:- 3rd layer of greater omentum, and structures forming stomach bed (transverse colon), transverse mesocolon, diaphragm, left kidney, left suprarenal gland, pancreas and splenic vessels).
    3. Right border: - Right free margin of greater omentum and floor of epiploic foramen.
    4. Left border: - Left free margin of greater omentum; gastrosplenic, linorenal and gastrophrenic ligaments.
    5. Upper border: - Reflection of peritoneum from esophagus to diaphragm.
    6. Lower border: - Continuation of2nd and 3m layers of greater omentum.
  3. Epiploic foramen (foramen of Winslow or aditus to lesser sac) is a slit-like opening through which lesser saccommunicates with greater sac. It is situated at the level of T12 vertebra. Its boundaries are :-
    1. Anterior: - Right free margin of lesser omentum (contains portal vein, hepatic artery proper and bile duct.
    2. Posterior :-IVC, right suprarenal gland and T 12 vertebra,
    3. Superior: - Caudate lobe of liver.
    4. Inferior: - 1st part of duodenum and horizontal part of hepatic artery.

A posterior gastric ulcer may perforate into lesser sac. The leaking fluid passes out through epiploic foramen to reach hepatorenal pouch.


Greater Sac


Greater sac is divided by line of attachment of transverse mesocolon and pelvic brim into three parts. : - (i) Supracolic (above transverse mesocolon), (ii) Infracolic (below transverse mesocolon upto pelvic brim) and (iii) Pelvic (below pelvic brim).


Supracolic compartment (subphrenic spaces)

  1. These spaces are just below diaphragm in relation to the liver. These space are:
    1. Intraperitoneal spaces are :-
      1. Left anterior space (left subphrenic space).
      2. Left posterior space (left sub hepatic space or lesser sac).
      3. Right anterior space, (right subphrenic space).
      4. Right posterior space (right sub hepatic space or hepatorenal pouch or Morrison’s pouch).
    2. Extraperitoneal spaces are:-
      1. Right and left extraperitoneal spaces.
      2. Midline extraperitoneal space (Bare area of liver).
  2. Hepatorenal pouch(Morrison's pouchis right posterior intraperitoneal spacewhich lies between right lobe of liver and gall bladder anteriorly; and right suprarenal gland, right kidney and 2nd part of duodenum posteriorly. It is the most dependent part of peritoneal cavity in supine position and is the most common site for subphrenic abscess.

Infracolic compartments


These are right and left infracolic compartments (divided by root of mesentery).


Pelvic peritoneal cavity


In males, rectovesical pouch of peritoneum intervenes between rectum and urinary bladder. Obliterated part of rectovesical pouch is called fascia ofDenonvilliers which separates posterior surface of prostate from rectum. In females rectouterine pouch (pouch of Douglas) lies between rectum (posteriorly) and uterus and posterior fornix of vagina (anteriorly). In females vesicouterine pouch lies between urinary bladder (anteriorly) and uterus posteriorly. The rectovesical pouch (in males) and rectouterine pouch (in females) are the most dependent portions of peritoneal cavity in erect posture.

Peritoneal Recesses

These are small pockets of peritoneal cavity enclosed by small, inconstant folds of peritoneum. These recesses are divided into

  1. Lesser sac (has been explained),
  2. duodenal recesses,
  3. caecal recesses and
  4. intersigmoid recess.

Duodenal recesses (or fossae)

  1. Superior duodenal recess: - It is present in 50% of subjects and lies opposite to L2 vertebra, to the left of 4th part of duodenum.
  2. Inferior duodenal recess: - Present in 75% of subjects and lies opposite to L3 vertebra, to the left of 4th part of duodenum.
  3. Retroduodenal recess: - It is present occasionally and is largest duodenal recess. It lies behind the 3rd and 4th parts of duodenum, anterior to abdominal aorta.
  4. Paraduodenal recess: - It is present in 20% of subjects, but is more common in newborns. It lies left and behind 4th part of duodenum. The inferior mesenteric vein lies in the free edge of peritoneal fold.
  5. Duodenojejunal (mesocolic) recess: - It is present in 20% of adults. It lies between duodeno-jejunal junction and root of transverse mesocolon, left to abdominal aorta.

Mesentericoparietal fossa of Waldeyer is present only in 1 % of adults and lies behind the upper part of mesentery. Superior mesenteric vessels lie in the fold of peritoneum covering this fossa


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Caecal recesses (or fossae)

  1. Superior Ileo caecalrecess: - It is commonly present. It is formed by a vascular fold present between ileum and ascending colon.
  2. Inferior lleocaecal recess: - It lies below the terminal ileum and in front of mesoappendix and is guarded by the ileocoecal fold (bloodless fold of Treves).
  3. Retrocaecal recess: - It lies behind the caecum bounded on either side by caecal folds.

Intersigmoid recess


This recess is constantly present in fetus and early infancy, but may disappear with age. It lies behind the apex of sigmoid mesocolon. Left ureter lies behind this recess.

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