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The abdominal cavity is the largest cavity in the body.
Extends from the diaphragm (above) to the pelvic inlet (below).
It contains most of the digestive organs, spleen, and parts of urogenital organs.
Lined by peritoneum, a serous membrane that encloses and supports viscera.
Boundaries:
Superiorly: Diaphragm.
Inferiorly: Continuous with pelvic cavity.
Anteriorly and laterally: Muscles of anterior and lateral abdominal wall.
Posteriorly: Lumbar vertebrae and posterior abdominal wall muscles.
Used for clinical localization of organs, pain, and incisions.
Transpyloric Plane:
Midway between suprasternal notch and pubic symphysis.
Passes through L1 vertebra, pylorus, neck of pancreas, hila of kidneys, and origin of superior mesenteric artery.
Transtubercular Plane:
Passes through tubercles of iliac crests and L5 vertebra.
Midclavicular lines (right and left).
Right hypochondriac
Epigastric
Left hypochondriac
Right lumbar (flank)
Umbilical
Left lumbar (flank)
Right iliac (inguinal)
Hypogastric (pubic)
Left iliac (inguinal)
Mnemonic:
→ “Hypo–Epi–Hypo / Lum–Umb–Lum / Ili–Hypo–Ili.”
Definition: Thin, transparent serous membrane lining the abdominal and pelvic cavities.
Divided into:
Parietal peritoneum: Lines abdominal wall.
Visceral peritoneum: Covers organs.
Peritoneal cavity:
Potential space between parietal and visceral layers.
Contains a thin film of serous fluid for lubrication.
In males → completely closed; in females → communicates with exterior via uterine tubes.
Mesentery — double fold connecting small intestine to posterior wall.
Omenta — peritoneal folds connecting stomach to other organs.
Ligaments — double layers connecting viscera to viscera or wall.
Fossae and recesses — small pouches formed by folds.
Lubrication:
Secretes serous fluid → reduces friction between moving viscera.
Suspension and Support:
Mesenteries and ligaments support organs and transmit blood vessels, nerves, and lymphatics.
Protection:
Greater omentum acts as a “policeman of the abdomen”, limiting spread of infection by adhering to inflamed areas.
Absorption:
Rich in blood and lymphatic capillaries; absorbs peritoneal fluid, drugs, and toxins.
Fat Storage:
Especially in omentum and mesentery, acts as an energy reserve.
Defence:
Contains macrophages and lymphocytes for local immune response.
Pathway for Spread:
Fluid, infection, or metastasis can spread along peritoneal reflections.
1. Ascites:
Abnormal accumulation of fluid in the peritoneal cavity due to cirrhosis, portal hypertension, or hypoproteinemia.
2. Peritonitis:
Inflammation due to infection (e.g., ruptured appendix, perforated ulcer).
Causes acute abdomen, rigid wall, pain, and fever.
May become generalized or localized (subphrenic abscess).
3. Peritoneal adhesions:
Fibrous bands between visceral and parietal layers following inflammation or surgery → cause intestinal obstruction.
4. Subphrenic abscess:
Localized pus beneath the diaphragm, often after appendicitis or hepatic infection.
5. Intraperitoneal vs Retroperitoneal organs:
Intraperitoneal → completely covered by peritoneum (stomach, liver, jejunum).
Retroperitoneal → partially covered (kidneys, pancreas, duodenum).
6. Peritoneal dialysis:
Exchange of solutes across peritoneum in renal failure; peritoneum acts as a semipermeable membrane.
7. Paracentesis abdominis:
Aspiration of ascitic fluid through the abdominal wall.
Safe site: Midline below umbilicus or lateral to rectus sheath.
8. Peritoneal recesses:
Small pouches where infection or pus may collect — subhepatic, paracolic, and pelvic recesses.
9. Pneumoperitoneum:
Presence of free gas in the peritoneal cavity — usually due to perforated hollow viscus (gas under diaphragm on X-ray).
The peritoneum, when reflected from the body wall to viscera or between viscera, forms folds that suspend organs and transmit vessels, nerves, and lymphatics.
Omenta → connect stomach to other viscera.
Mesenteries → connect intestines to posterior abdominal wall.
Ligaments → connect viscera to viscera or wall (e.g. falciform ligament).
Fossae and recesses → small pouches between folds.
Each fold consists of two layers of peritoneum enclosing connective tissue, fat, blood vessels, lymphatics, and nerves.
Definition: A large, apron-like peritoneal fold hanging from the greater curvature of stomach and first part of duodenum, covering the intestines.
Superiorly: Greater curvature of stomach and 1st part of duodenum.
Inferiorly: Hangs down in front of small intestines, then turns upward to attach to the transverse colon and its mesocolon.
Consists of four layers of peritoneum:
Formed by the double layer descending from the stomach → turns upward in front of the transverse colon → fuses with its mesocolon.
Fat, lymphatics, gastroepiploic vessels, and macrophages.
Acts as “abdominal policeman” – migrates to inflamed organs to wall off infection.
Provides protection and insulation for abdominal viscera.
Acts as fat reservoir.
Limits spread of peritonitis.
Reflect the omentum upwards to expose:
Transverse colon and small intestines.
Note that stomach lies behind the omental curtain.
Observe the four-layered fold and the gastrosplenic ligament at its left border.
A double-layered peritoneal fold connecting lesser curvature of stomach and first part of duodenum to liver.
Superior border: Fissure for ligamentum venosum and porta hepatis of liver.
Inferior border: Lesser curvature of stomach and 1st part of duodenum.
Hepatogastric ligament – between liver and stomach.
Hepatoduodenal ligament – between liver and duodenum; forms anterior wall of epiploic foramen.
Hepatic artery proper (left).
Bile duct (right).
Portal vein (posterior).
Mnemonic: Duct right, artery left, vein behind.
Connects liver with stomach and duodenum.
Transmits portal triad structures.
Separates greater and lesser sacs of peritoneal cavity.
A fan-shaped peritoneal fold connecting coils of jejunum and ileum to the posterior abdominal wall.
Length: About 15 cm.
Direction: Oblique — from duodenojejunal flexure (left of L2) to ileocecal junction (right sacroiliac joint).
Length of free border: 6 meters (supports small intestine).
Branches of superior mesenteric artery and vein.
Lymph nodes and lacteals.
Nerves and fat.
Provides mobility and vascular support to small intestine.
Acts as pathway for vessels and lymphatics.
A triangular peritoneal fold connecting appendix to the mesentery of the terminal ileum.
Contains the appendicular artery and vein (branch of ileocolic artery).
Clinical significance:
Site of inflammation in appendicitis; artery may thrombose during infection causing gangrene of appendix.
Lift coils of small intestine → identify the fan-shaped mesentery attaching to posterior abdominal wall.
Trace the superior mesenteric vessels within the root.
Identify the appendix and its mesoappendix extending from terminal ileum.
Note presence of appendicular artery (lies close to free edge).
Omental adhesions: Occur post-surgery or infection, may cause intestinal obstruction.
Internal hernias: May occur through defects in mesentery or foramen of Winslow.
Epiploic foramen (of Winslow): Communication between greater and lesser sacs — bounded by:
Anteriorly: Hepatoduodenal ligament.
Posteriorly: IVC.
Superiorly: Caudate lobe of liver.
Inferiorly: 1st part of duodenum.
Foramen of Winslow occlusion test (Pringle maneuver): Compression of hepatoduodenal ligament to control hepatic bleeding.
A broad peritoneal fold that connects the transverse colon to the posterior abdominal wall.
It divides the peritoneal cavity into supracolic and infracolic compartments.
Superior border: Attached to anterior surface of pancreas.
Inferior border: Attached to transverse colon.
Root: Extends horizontally across the posterior abdominal wall, passing:
From right kidney → across 2nd part of duodenum → to left kidney.
Middle colic vessels (from superior mesenteric artery and vein).
Lymphatics and autonomic nerves.
Fat and connective tissue.
Provides mobility to the transverse colon and acts as a pathway for vessels.
Divides peritoneal cavity for clinical localization of infections.
Reflect the greater omentum upward to expose the transverse colon.
Lift the colon gently → observe the posterior attachment (root) of the mesocolon to the pancreas.
Identify the middle colic artery and vein between the two layers.
Note continuity of the greater omentum with the transverse mesocolon.
A triangular peritoneal fold connecting the sigmoid colon to the posterior pelvic wall.
Shape: Inverted “V”
Apex: Over the bifurcation of left common iliac artery.
Right limb: Along sacral promontory.
Left limb: Along the medial border of left psoas major and pelvic brim.
Sigmoid branches of inferior mesenteric artery and vein.
Lymphatics and nerves.
Fat and connective tissue.
Suspends the sigmoid colon, allowing mobility for defecation.
Serves as a conduit for vessels.
Retract small intestine to right.
Identify the loop of sigmoid colon in the left iliac fossa.
Lift the sigmoid loop → observe fan-shaped sigmoid mesocolon.
Trace the inferior mesenteric vessels within its layers.
The parietal peritoneum reflects from the abdominal wall to cover viscera, forming ligaments, mesenteries, and omenta.
Reflections create peritoneal pouches and recesses between organs.
From diaphragm to liver → Falciform, coronary, and triangular ligaments.
From stomach to other organs → Greater and lesser omenta, gastrosplenic and gastrophrenic ligaments.
From small and large intestine to posterior wall → Mesentery, transverse mesocolon, sigmoid mesocolon.
From anterior abdominal wall to bladder and uterus (in females) → Vesicouterine and rectouterine pouches.
Sites of peritoneal fluid accumulation in disease (e.g., subphrenic space, rectouterine pouch).
Important in surgical approaches to retroperitoneal organs.
A potential space between the parietal and visceral layers of peritoneum, containing a thin film of lubricating fluid.
Greater Sac
Main and larger part of the cavity.
Divided into:
Supracolic compartment → contains stomach, liver, spleen.
Infracolic compartment → contains small intestine, ascending & descending colon.
These compartments are separated by the transverse mesocolon.
Lesser Sac (Omental Bursa)
Posterior to stomach and lesser omentum.
Communicates with greater sac via epiploic (omental) foramen.
Subphrenic space (beneath diaphragm).
Subhepatic (Morrison’s pouch) – common site for pus or fluid collection.
Paracolic gutters (lateral to ascending and descending colon).
Pelvic pouches – rectovesical (males), rectouterine (females).
Allows free movement of viscera.
Serves as a lubricated environment for digestion and absorption.
Acts as a pathway for infection, metastasis, and fluid spread.
Subphrenic abscess: Accumulation of pus beneath diaphragm.
Morrison’s pouch fluid: Seen in supine patients with peritonitis or liver abscess.
Pelvic abscess: Settles in lowest pouch (rectouterine/rectovesical).
Internal hernia: May occur into recesses near duodenum or cecum.
Ascitic fluid flow: Moves between supracolic and infracolic compartments depending on posture.
Pneumoperitoneum: Air under diaphragm due to perforated hollow organ.
A vertical or sagittal tracing is made in the midline, showing how the peritoneum reflects from the anterior abdominal wall onto viscera and posterior wall.
Begins on the posterior surface of the anterior abdominal wall below the xiphoid process.
Passes backward over the anterior surface of the liver to the superior surface, forming the falciform ligament.
Reflects from the posterior surface of the liver to the diaphragm as the coronary and triangular ligaments.
Descends to enclose the stomach (forming its anterior and posterior peritoneal layers).
From the greater curvature of the stomach, it descends as the greater omentum, then turns upward to the transverse colon and transverse mesocolon.
From the posterior abdominal wall, it passes forward to cover coils of small intestine and then reflects again onto the wall.
In the pelvis, it covers the urinary bladder, forms pouches, and reflects onto the rectum.
A horizontal section at the level of the upper abdomen shows peritoneal relations of stomach, liver, and spleen.
Anteriorly: Parietal peritoneum lines the anterior abdominal wall.
Superiorly: Reflects onto the inferior surface of the diaphragm.
On the right side: Covers the inferior surface of the liver, forming the coronary ligament and the hepatorenal pouch (Morrison’s pouch).
In the midline:
Encloses the stomach — anterior and posterior surfaces covered.
Forms lesser omentum between stomach and liver.
Forms greater omentum from greater curvature.
On the left side: Covers spleen, gastrosplenic, and splenorenal ligaments.
Posteriorly: Covers the pancreas and posterior abdominal wall structures.
Compartments visible:
Supracolic compartment: Above the transverse mesocolon, containing stomach, liver, spleen.
Subphrenic spaces: Right and left, separated by falciform ligament.
This tracing shows the peritoneal disposition around the small and large intestines (infracolic compartment).
The transverse mesocolon divides the cavity; below it lies the infracolic compartment.
Right infracolic compartment: Between mesentery and ascending colon.
Left infracolic compartment: Between mesentery and descending colon.
Both communicate inferiorly with the pelvic peritoneum.
The paracolic gutters (lateral to ascending and descending colon) serve as pathways for fluid spread between pelvis and subphrenic regions.
Peritoneum covers:
Small intestine completely (jejunum and ileum).
Cecum partially, often with a mesocecum.
Ascending and descending colon — only anterior and lateral surfaces (retroperitoneal).
Clinical note:
Infections may move freely through right paracolic gutter (continuous with Morrison’s pouch) and collect in pelvic recesses.
From the anterior abdominal wall, the peritoneum descends onto the superior surface of the urinary bladder.
When the bladder is empty, it reaches the level of the pubic symphysis; when full, it rises above it.
Reflects from the bladder to the anterior surface of the rectum, forming the rectovesical pouch (lowest part of the peritoneal cavity in males).
Covers the upper one-third of the rectum and then reflects backward onto the sacrum.
Rectovesical pouch: Between bladder and rectum → lowest point for pus/fluid in the male peritoneal cavity.
Pararectal fossae: On each side of the rectum.
From the anterior abdominal wall, peritoneum covers the superior surface of the urinary bladder.
Passes backward onto the anterior surface of the uterus, forming the vesicouterine pouch.
Then reflects over the fundus and posterior surface of the uterus onto the upper part of vagina and anterior surface of the rectum, forming the rectouterine pouch (pouch of Douglas).
Covers the broad ligaments of uterus on either side, enclosing uterine tubes and ovaries (partly).
Vesicouterine pouch: Between bladder and uterus.
Rectouterine pouch (Douglas): Between uterus and rectum — lowest point in the female peritoneal cavity.
Douglas pouch tap (culdocentesis): Fluid from pelvic peritonitis or ruptured ectopic pregnancy can be aspirated here.
Infections or blood may collect due to gravity in this pouch.
Right paracolic gutter: Pathway for spread of subhepatic infection to pelvis.
Left paracolic gutter: Limited by phrenicocolic ligament, preventing upward spread.
Morrison’s pouch (hepatorenal recess): Common site for pus or fluid in supine patients.
Pelvic pouches (male or female): Lowest dependent areas for abscess formation.
Rectouterine pouch (Douglas): Clinically accessed through posterior fornix for drainage.
Rectovesical pouch: Fluid collects here in males when supine.
The epiploic foramen is the natural communication between the greater sac and lesser sac (omental bursa) of the peritoneal cavity.
It allows the passage of structures of the portal triad and permits movement of peritoneal fluid between compartments.
Lies posterior to the free right border of the lesser omentum (hepatoduodenal ligament).
Positioned behind the right margin of the stomach and in front of the inferior vena cava.
| Boundary | Structure |
|---|---|
| Anterior | Free border of lesser omentum containing portal triad (bile duct, hepatic artery, portal vein). |
| Posterior | Inferior vena cava, covered by peritoneum. |
| Superior | Caudate process of liver. |
| Inferior | First part of duodenum. |
Mnemonic: “A VIP Doorway” → Anterior: Vein-Portal triad, Inferior: Duodenum, Posterior: IVC, Superior: Process (Caudate).
Pringle’s Maneuver:
During liver surgery, hepatic bleeding can be controlled by compressing the hepatoduodenal ligament across the foramen → occludes hepatic artery and portal vein.
Internal Hernia:
Small intestine loops may enter the lesser sac through this foramen, leading to strangulated hernia.
Spread of Infection:
Pathological fluid or pus can pass between lesser sac and greater sac through this foramen.
The lesser sac is a peritoneal recess situated posterior to the stomach and lesser omentum.
It allows free movement of the stomach and acts as a potential space for infection or fluid accumulation.
Lies behind the stomach, lesser omentum, and left lobe of liver.
Communicates with greater sac via the epiploic foramen on the right side.
| Wall | Structures Forming the Wall |
|---|---|
| Anterior wall | Lesser omentum, posterior surface of stomach, anterior layer of greater omentum. |
| Posterior wall | Peritoneum covering pancreas, left kidney, left suprarenal gland, and transverse mesocolon. |
| Superior wall | Caudate lobe of liver and diaphragm. |
| Inferior wall | Fusion of layers of greater omentum with transverse mesocolon. |
| Left margin | Spleen, gastrosplenic ligament, and splenorenal ligament. |
| Right margin | Opens into greater sac via epiploic foramen. |
Superior recess: Between diaphragm and caudate lobe of liver.
Inferior recess: Extends downward between layers of greater omentum (often obliterated in adults).
Splenic recess: Extends toward spleen between gastrosplenic and splenorenal ligaments.
Abscess formation: Infections posterior to the stomach may form subhepatic or lesser sac abscess.
Perforation of posterior gastric ulcer: Gastric contents may enter the lesser sac, causing peritonitis.
Pancreatic pseudocyst: Pancreatic secretions may collect in the lesser sac through ruptured posterior wall of the pancreas.
Surgical approach: The lesser sac is reached by dividing the gastrocolic ligament (part of the greater omentum).
The peritoneal cavity is subdivided into compartments and recesses that determine fluid movement and abscess localization.
Liver, stomach, spleen, and upper duodenum.
Right subphrenic space: Between right dome of diaphragm and liver.
Left subphrenic space: Between left dome of diaphragm and spleen/stomach.
Subhepatic space: Between inferior surface of liver and transverse colon.
Clinical Note:
Subphrenic abscess or subhepatic abscess can follow peritonitis, appendicitis, or cholecystitis.
A deep recess of subhepatic space between the right kidney and posterior surface of liver.
It is the lowest part of the supracolic compartment in the supine position.
Clinical importance:
Fluid or pus from the peritoneal cavity tends to collect here.
Visible on ultrasound or CT scan in cases of peritonitis or ascites.
Divided into right and left infracolic spaces by the mesentery of small intestine.
Right infracolic space: Lies between mesentery and ascending colon.
Left infracolic space: Between mesentery and descending colon.
Jejunum, ileum, ascending and descending colon.
Communication:
Both infracolic compartments open inferiorly into the pelvic cavity, allowing free flow of ascitic fluid.
Longitudinal channels between lateral borders of colon and posterior abdominal wall.
Right paracolic gutter: Between ascending colon and abdominal wall.
Wide and deep, communicates with Morrison’s pouch and pelvic cavity.
Major route for spread of infection between pelvis and subhepatic region.
Left paracolic gutter: Between descending colon and abdominal wall.
Shallow, limited superiorly by phrenicocolic ligament (supports spleen).
Restricts upward spread of infection.
Fluid movements:
In supine patients, fluid accumulates in Morrison’s pouch.
In erect posture, it collects in pelvic pouches (rectovesical or rectouterine).
Subphrenic abscess: Pus beneath diaphragm — may irritate phrenic nerve, causing shoulder pain.
Internal hernia: May occur into lesser sac through epiploic foramen.
Perforated ulcer: Gastric contents may enter lesser sac.
Pancreatic leakage: Leads to lesser sac pseudocyst.
The lowest part of the peritoneal cavity in females, situated between the uterus and the rectum.
Formed by a downward reflection of peritoneum from the posterior surface of uterus and upper vagina onto the anterior surface of rectum.
Anterior: Posterior wall of uterus and upper part of posterior vaginal fornix.
Posterior: Anterior surface of rectum.
Lateral: Uterosacral ligaments.
Floor: Formed by peritoneum over the posterior vaginal fornix.
Extends about 6–8 cm above the vaginal opening; deepest peritoneal recess in the female pelvis.
Superiorly: Posterior fornix of vagina.
Inferiorly: Rectum.
Laterally: Broad ligaments and uterosacral folds.
Lowest dependent point → Fluid, pus, or blood collects here in erect posture.
Culdocentesis:
Aspiration of fluid through posterior vaginal fornix to confirm pelvic peritonitis, ruptured ectopic pregnancy, or hemoperitoneum.
Pouch of Douglas abscess: May follow pelvic inflammatory disease.
Rectouterine pouch obliteration: Seen in endometriosis or chronic pelvic infections.
Douglas’ pouch hernia (enterocoele):
Herniation of intestinal loop into the pouch, often following childbirth or weakness of pelvic floor.
Small peritoneal pouches formed by folds and reflections — potential sites for internal hernias or localized collections.
Superior duodenal recess: Above the duodenojejunal flexure; bounded by superior duodenal fold.
Inferior duodenal recess: Below the flexure; bounded by inferior duodenal fold.
Paraduodenal recess: Left of duodenojejunal flexure; contains inferior mesenteric vein in its fold — common site for internal hernia.
Retroduodenal recess: Behind the flexure; variable in size.
Superior ileocecal recess: Above the junction of ileum and cecum.
Inferior ileocecal recess: Below the junction; bounded by vascular fold of ileocecal artery.
Retrocecal recess: Behind cecum; appendix commonly lies here.
Paracecal recess: Lateral to cecum; communicates with right paracolic gutter.
Found at root of sigmoid mesocolon; contains left ureter on its floor.
Formed by peritoneal folds in the pelvis, adjacent to bladder and rectum.
Internal hernias may occur through duodenal, paraduodenal, or ileocecal recesses.
Paraduodenal hernia: Dangerous because inferior mesenteric vein lies in the fold — risk of injury during surgery.
Retrocecal appendix: May cause atypical appendicitis pain (flank or back).
Pelvic recess abscesses: Common after pelvic inflammatory disease or perforated bowel.
Derived from endoderm-lined yolk-sac portion incorporated during folding of embryo.
Divided into:
Foregut: From buccopharyngeal membrane to second part of duodenum.
Midgut: From distal half of duodenum to two-thirds of transverse colon.
Hindgut: From distal one-third of transverse colon to cloacal membrane.
As gut tube elongates, it remains suspended by dorsal mesentery throughout and ventral mesentery in foregut region only.
Later differentiation produces:
Omenta → from ventral mesogastrium (lesser omentum) and dorsal mesogastrium (greater omentum).
Ligaments → falciform ligament, gastrosplenic and splenorenal ligaments.
Mesenteries → mesentery of small intestine, transverse and sigmoid mesocolons.
Midgut rotates 270° counter-clockwise around superior mesenteric artery, placing:
Jejunum & ileum centrally,
Cecum in right lower quadrant,
Colon ascending and descending secondarily retroperitoneal.
Fusion of peritoneal layers causes fixation of ascending and descending colon to posterior wall (no mesentery).
Errors in rotation → malrotation, volvulus, or internal hernias.
Persistent dorsal mesentery → mobile cecum or mobile colon.
Persistence of vitelline duct (yolk-stalk) → Meckel’s diverticulum, may ulcerate or bleed.
Abnormal omental fusion → internal hernial pouches.
Pouch of Douglas → lowest peritoneal space in female, accessed by culdocentesis.
Rectovesical pouch → male counterpart.
Fossae → sites for internal hernia.
Midgut rotation (270°) → defines adult intestinal arrangement.
The peritoneum is the largest serous membrane of the body, forming a closed sac in males and an open sac in females (communicating via the uterine tubes).
The peritoneal cavity is a potential space containing lubricating serous fluid, allowing free movement of viscera.
Greater sac and lesser sac (omental bursa) are the two major subdivisions of the peritoneal cavity.
Epiploic foramen (Foramen of Winslow) is the only natural communication between these two sacs.
The portal triad (bile duct, hepatic artery, portal vein) lies in the anterior wall of the epiploic foramen within the hepatoduodenal ligament.
Greater omentum hangs from the greater curvature of the stomach and acts as the policeman of the abdomen by localizing infections.
Lesser omentum connects the stomach and duodenum to the liver; it transmits the portal triad.
Mesentery suspends small intestine and contains branches of the superior mesenteric artery and vein.
Transverse mesocolon divides the peritoneal cavity into supracolic and infracolic compartments.
Paracolic gutters act as channels for fluid movement between pelvis and subphrenic spaces.
Morrison’s pouch (hepatorenal recess) is the lowest part of the supracolic compartment when supine.
In females, the pouch of Douglas (rectouterine pouch) is the lowest part of the peritoneal cavity when erect.
Subphrenic abscess may irritate the phrenic nerve, leading to referred shoulder pain.
Paraduodenal recess is the commonest site of internal hernia, containing the inferior mesenteric vein.
Peritoneal folds and ligaments develop from ventral and dorsal mesenteries of the embryonic gut.
The midgut rotates 270° anticlockwise around the superior mesenteric artery during development.
Fusion fascia fixes the ascending and descending colon to the posterior abdominal wall.
Meckel’s diverticulum represents persistence of the vitelline duct — located on antimesenteric border of ileum.
Peritoneal dialysis uses the semipermeable property of peritoneum for removal of waste products in renal failure.
Ascitic fluid follows gravity-dependent spaces: Morrison’s pouch (supine) and pelvic pouches (erect).
A patient presents with dull, aching pain in right shoulder following liver abscess.
→ Due to irritation of phrenic nerve from subphrenic abscess beneath diaphragm.
In a supine patient with peritonitis, where does pus first collect?
→ In the hepatorenal pouch (Morrison’s pouch) — the lowest point in this position.
In an erect female patient, where does peritoneal fluid accumulate?
→ In the rectouterine pouch (Pouch of Douglas).
A posterior gastric ulcer perforates — where will the gastric contents go?
→ Into the lesser sac (omental bursa).
A loop of intestine herniates behind the stomach. What is the route?
→ Through the epiploic foramen into the lesser sac (internal hernia).
During hepatic surgery, bleeding is controlled by clamping the hepatoduodenal ligament. What is this called?
→ Pringle’s maneuver, which occludes hepatic artery and portal vein.
A newborn presents with intestinal obstruction due to malrotation.
→ Results from failure of normal 270° rotation of midgut loop around superior mesenteric artery.
Internal hernia through paraduodenal fossa causes bowel obstruction. Why is it dangerous?
→ Because inferior mesenteric vein lies in its fold and may be damaged during surgery.
A patient has persistent bleeding from Meckel’s diverticulum.
→ Due to ectopic gastric mucosa secreting acid → ulceration and bleeding.
Post-surgical adhesions between omentum and intestines cause intestinal obstruction.
→ Due to fibrous bands following peritoneal inflammation.
Fluid seen on ultrasound in the hepatorenal space in supine position.
→ Indicates peritonitis, ascites, or ruptured viscera — fluid gravitates to Morrison’s pouch.
Ectopic pregnancy ruptures in fallopian tube — where does blood collect first?
→ In the pouch of Douglas (lowest peritoneal space in female).
Chronic pelvic pain and infertility in a woman.
→ May result from peritoneal adhesions or obliteration of pouch of Douglas in endometriosis.
Fluid detected under diaphragm on erect X-ray.
→ Suggests pneumoperitoneum due to perforated hollow viscus (e.g., gastric or duodenal ulcer).
A patient develops severe right-sided abdominal pain after peritoneal dialysis.
→ May be due to peritoneal irritation or infection (peritonitis).
Rupture of pancreas leads to fluid behind stomach.
→ Accumulation occurs in lesser sac, forming pancreatic pseudocyst.
Chronic constipation with mobile colon.
→ Due to failure of fixation of descending colon to posterior abdominal wall.
Localized peritonitis remains confined around appendix. Why?
→ Greater omentum migrates and walls off infection → “policeman of abdomen”.
During surgery for hernia, surgeon notes intestine trapped beneath mesentery of duodenum.
→ Indicates paraduodenal internal hernia.
An elderly patient with ascites shows fluid shifting from upper abdomen to pelvis upon posture change.
→ Due to communication between supracolic and infracolic compartments via paracolic gutters.
It is a serous membrane lining the abdominal and pelvic cavities and covering the viscera. It consists of:
Parietal peritoneum (lining wall)
Visceral peritoneum (covering organs)
Greater sac — the main and larger part of the cavity.
Lesser sac (Omental bursa) — a smaller space behind the stomach and lesser omentum.
They communicate through the epiploic foramen (Foramen of Winslow).
Omenta (greater and lesser)
Mesenteries (mesentery of small intestine, transverse and sigmoid mesocolon)
Ligaments (falciform, gastrosplenic, splenorenal, etc.)
Lubrication for visceral movement.
Support of organs through ligaments and mesenteries.
Defense (contains macrophages, lymphatics).
Absorption and fat storage.
Infection localization via greater omentum.
A large four-layered peritoneal fold descending from the greater curvature of the stomach and first part of duodenum, then folding back to attach to the transverse colon.
Because it migrates toward inflamed or infected areas (e.g. appendix, perforated ulcer) and walls them off, preventing spread of infection.
A two-layered fold connecting lesser curvature of stomach and first part of duodenum to the liver.
It contains the portal triad:
Bile duct (right)
Hepatic artery (left)
Portal vein (behind)
A natural opening between the greater and lesser sacs.
Boundaries:
Anterior: Portal triad (in hepatoduodenal ligament)
Posterior: IVC
Superior: Caudate process of liver
Inferior: First part of duodenum
A surgical maneuver to control hepatic bleeding by compressing the hepatoduodenal ligament, which temporarily occludes the hepatic artery and portal vein.
Supracolic compartment: Above transverse mesocolon (liver, stomach, spleen)
Infracolic compartment: Below it (small intestine, ascending and descending colon)
Pelvic cavity: Continuation below
Also called the hepatorenal pouch, it lies between the right kidney and the posterior surface of liver.
It is the lowest part of the supracolic compartment when supine.
The rectouterine pouch (Pouch of Douglas) — between uterus and rectum.
The rectovesical pouch, between urinary bladder and rectum.
Pus beneath the diaphragm → irritates phrenic nerve (C3–C5) → referred pain to shoulder tip (same dermatome as supraclavicular nerve).
A peritoneal pocket near the duodenojejunal flexure containing the inferior mesenteric vein.
It is a common site for internal hernia, which can cause intestinal obstruction.
Grooves on either side of the colon that allow flow of peritoneal fluid:
Right gutter: Communicates freely between pelvis and Morrison’s pouch.
Left gutter: Limited by phrenicocolic ligament (near spleen).
A true diverticulum of the ileum, representing a remnant of the vitelline duct.
Located about 2 feet from ileocecal junction, 2 inches long, may cause bleeding or obstruction.
Site of abscess after posterior gastric ulcer or pancreatitis.
May contain pancreatic pseudocyst.
Internal hernia can occur through epiploic foramen into this sac.
A medical procedure where the peritoneum acts as a semipermeable membrane to exchange waste, electrolytes, and fluid — used in renal failure.
Ascites: Accumulation of fluid in peritoneal cavity (e.g. cirrhosis, portal hypertension).
Peritonitis: Inflammation of peritoneum due to infection or perforation; presents with rigid abdomen and severe pain.
Derived from dorsal and ventral mesenteries of the primitive gut.
Ventral mesentery: Forms lesser omentum and falciform ligament.
Dorsal mesentery: Forms greater omentum, mesentery, and other ligaments.
The midgut loop rotates 270° anticlockwise around the superior mesenteric artery, placing:
Jejunum and ileum centrally,
Cecum in right iliac fossa,
Colon ascending and descending secondarily retroperitoneal.
An organ covered by peritoneum only on its anterior surface, e.g. kidneys, pancreas, duodenum (except 1st part), ascending and descending colon.
They serve as sites for internal hernia or localized infection, especially paraduodenal and ileocecal fossae.
Supine position: Morrison’s pouch.
Erect position: Pelvic pouches (rectovesical in males, rectouterine in females).
Mesentery: Double layer of peritoneum connecting intestine to posterior wall.
Omentum: Double layer connecting stomach to another organ.
Lesser omentum — contains hepatic artery, bile duct, portal vein.
Gastrosplenic ligament — transmits short gastric and left gastroepiploic arteries.
Fibrous adhesions following inflammation or surgery can restrict gut movement and cause intestinal obstruction.
Free gas in peritoneal cavity due to perforated hollow organ — seen as air under diaphragm on erect X-ray.
Because it serves as a fat storage organ and insulator, containing variable adipose tissue.
1. The peritoneum is derived from which embryonic layer?
a. Ectoderm
b. Mesoderm
c. Endoderm
d. Mesenchyme
2. The peritoneal cavity in males is:
a. Open to exterior through genital tract
b. A closed cavity
c. Communicates with urinary bladder
d. Absent below diaphragm
3. The peritoneal cavity in females communicates with exterior through:
a. Rectum
b. Uterus only
c. Uterine tubes
d. Urethra
4. The lesser sac (omental bursa) lies:
a. Anterior to stomach
b. Posterior to stomach and lesser omentum
c. Between transverse colon and jejunum
d. Below sigmoid mesocolon
5. The greater omentum connects:
a. Lesser curvature of stomach to liver
b. Greater curvature of stomach to transverse colon
c. Stomach to posterior abdominal wall
d. Duodenum to pancreas
6. The epiploic foramen communicates between:
a. Right and left paracolic gutters
b. Infracolic and supracolic compartments
c. Greater sac and lesser sac
d. Subphrenic and subhepatic spaces
7. The anterior wall of the epiploic foramen is formed by:
a. Inferior vena cava
b. Hepatoduodenal ligament containing the portal triad
c. First part of duodenum
d. Caudate lobe of liver
8. The lowest part of the peritoneal cavity in the erect female is:
a. Subhepatic space
b. Rectovesical pouch
c. Rectouterine pouch (Pouch of Douglas)
d. Right paracolic gutter
9. The lowest part of the peritoneal cavity in the erect male is:
a. Subphrenic space
b. Rectovesical pouch
c. Infracolic compartment
d. Morrison’s pouch
10. The hepatorenal pouch (Morrison’s pouch) lies between:
a. Liver and diaphragm
b. Liver and right kidney
c. Stomach and pancreas
d. Duodenum and transverse colon
11. Which structure divides the peritoneal cavity into supracolic and infracolic compartments?
a. Greater omentum
b. Mesentery
c. Transverse mesocolon
d. Falciform ligament
12. Which of the following spaces is the lowest in the supine position?
a. Rectouterine pouch
b. Rectovesical pouch
c. Hepatorenal pouch (Morrison’s pouch)
d. Subphrenic space
13. The greater omentum contains which vessels?
a. Left gastric artery
b. Right and left gastroepiploic arteries
c. Middle colic artery
d. Splenic artery
14. The Pringle’s maneuver is used to control bleeding from:
a. Stomach
b. Duodenum
c. Liver
d. Pancreas
15. The mesentery of small intestine transmits branches of:
a. Celiac trunk
b. Superior mesenteric artery and vein
c. Inferior mesenteric artery
d. Internal iliac artery
16. The peritoneal fold that attaches liver to anterior abdominal wall is:
a. Falciform ligament
b. Lesser omentum
c. Coronary ligament
d. Hepatoduodenal ligament
17. The left paracolic gutter is limited superiorly by:
a. Hepatorenal ligament
b. Lesser omentum
c. Phrenicocolic ligament
d. Gastrosplenic ligament
18. The pouch of Douglas (rectouterine pouch) is bounded anteriorly by:
a. Rectum
b. Posterior wall of uterus and vagina
c. Bladder
d. Sacrum
19. The most common site of internal hernia in abdomen is:
a. Retroduodenal recess
b. Intersigmoid fossa
c. Paraduodenal recess
d. Inferior ileocecal recess
20. Meckel’s diverticulum develops from persistence of:
a. Allantoic duct
b. Cloacal membrane
c. Vitelline (omphalomesenteric) duct
d. Median umbilical ligament
21. The midgut rotates during development around which vessel?
a. Celiac trunk
b. Superior mesenteric artery
c. Inferior mesenteric artery
d. Portal vein
22. The total degree of midgut rotation during development is:
a. 90° clockwise
b. 180° clockwise
c. 270° anticlockwise
d. 360° clockwise
23. The peritoneal fold enclosing the appendix and its vessels is the:
a. Mesentery
b. Mesoappendix
c. Sigmoid mesocolon
d. Hepatoduodenal ligament
24. The organ which is secondarily retroperitoneal is:
a. Stomach
b. Ascending colon
c. Jejunum
d. Appendix
25. The “policeman of the abdomen” refers to:
a. Liver
b. Mesentery
c. Greater omentum
d. Falciform ligament
✅ Answer Key Summary
| Q | Answer | Q | Answer | Q | Answer | Q | Answer | Q | Answer |
|---|---|---|---|---|---|---|---|---|---|
| 1 | b | 6 | c | 11 | c | 16 | a | 21 | b |
| 2 | b | 7 | b | 12 | c | 17 | c | 22 | c |
| 3 | c | 8 | c | 13 | b | 18 | b | 23 | b |
| 4 | b | 9 | b | 14 | c | 19 | c | 24 | b |
| 5 | b | 10 | b | 15 | b | 20 | c |
It is a serous membrane that lines the abdominal and pelvic cavities and covers most of the viscera, forming parietal and visceral layers.
A potential space between parietal and visceral layers containing serous fluid, which allows free movement of abdominal organs.
In males, it is a closed sac.
In females, it communicates with exterior through uterine tubes, uterus, and vagina.
Greater sac
Lesser sac (Omental bursa)
Through the epiploic foramen (Foramen of Winslow).
Anterior: Hepatoduodenal ligament (portal triad)
Posterior: Inferior vena cava
Superior: Caudate lobe of liver
Inferior: First part of duodenum
It allows access to the portal triad — during Pringle’s maneuver, the hepatoduodenal ligament is clamped to control hepatic bleeding.
Bile duct (right)
Hepatic artery proper (left)
Portal vein (posteriorly)
Because it migrates to inflamed organs and walls off infection, preventing peritonitis from spreading.
The transverse mesocolon.
Stomach, liver, and spleen.
Small intestine, ascending and descending colon.
Also called the hepatorenal recess — a space between right kidney and posterior surface of liver; it is the lowest part of the supracolic compartment in supine posture.
The rectouterine pouch (Pouch of Douglas).
The rectovesical pouch.
They are grooves on the lateral sides of ascending and descending colon.
Right paracolic gutter: Route for infection spread between pelvis and subhepatic space.
Left paracolic gutter: Limited by phrenicocolic ligament, restricting spread.
Small pockets formed by peritoneal folds, e.g. duodenal, paraduodenal, and ileocecal recesses — potential sites for internal hernia.
The paraduodenal recess (left of duodenojejunal flexure).
Commonly in the retrocecal recess behind the cecum.
A fan-shaped peritoneal fold connecting small intestine to posterior wall; contains superior mesenteric vessels, lymphatics, and nerves.
Mesentery: Connects intestine to posterior abdominal wall.
Omentum: Connects stomach to other viscera.
They arise from ventral and dorsal mesenteries of the embryonic gut.
270° anticlockwise around the superior mesenteric artery.
It may lead to malrotation, volvulus, or internal hernia.
A remnant of the vitelline duct, located on antimesenteric border of ileum about 2 feet from ileocecal junction — may ulcerate, bleed, or mimic appendicitis.
Organs that were initially intraperitoneal but became fixed to posterior wall after fusion of mesentery — duodenum (except 1st part), pancreas, ascending and descending colon.
A therapeutic process where peritoneum acts as a semipermeable membrane for exchange of solutes and fluid — used in renal failure.
Abnormal accumulation of fluid in peritoneal cavity, commonly due to portal hypertension, cirrhosis, or hypoproteinemia.
Inflammation of peritoneum caused by bacterial contamination or perforation of hollow viscera.
Because the inflamed parietal peritoneum causes reflex contraction of abdominal muscles.
Because it irritates the phrenic nerve (C3–C5), leading to referred pain to the shoulder tip via the supraclavicular nerve.
Surgical compression of hepatoduodenal ligament across epiploic foramen to temporarily occlude portal vein and hepatic artery during hepatic bleeding.
It provides lubrication, allows smooth visceral movements, and contains immune cells for defense.
The gastric contents enter the lesser sac, causing localized peritonitis or abscess.
It is the lowest part of peritoneal cavity in erect female, where fluid, pus, or blood collects — accessed by culdocentesis through posterior vaginal fornix.
Because it acts as a fat storage organ and provides thermal insulation for abdominal viscera.
It localizes infection via adhesion formation, absorption of toxins, and increased lymphatic drainage.
Intraperitoneal: Completely covered by peritoneum (stomach, jejunum, spleen).
Retroperitoneal: Covered only anteriorly (kidneys, pancreas, duodenum, ascending and descending colon).
Presence of free gas under diaphragm — indicates perforation of a hollow viscus (e.g. gastric ulcer, intestinal perforation).
An abscess below the liver, often within Morrison’s pouch — may follow appendicitis, cholecystitis, or perforated duodenal ulcer.
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