Anatomy of the Peritoneum

Overview

• The peritoneum is a serous membrane lining the abdominal cavity and surrounding organs.
• It protects and fixates organs and creates a moist environment for them.

Parts of the Peritoneum

1. Parietal Peritoneum

• Location: Lines the internal surface of the abdominal and pelvic walls.
• Structure: Wraps around front, sides, and back of the abdomen.

2. Visceral Peritoneum

• Location: Covers the walls of the organs in the abdominal cavity.
• Function: Forms a wet, serous coat for the organs.
• Cavity: Contains serous fluid produced by both peritoneum parts, known as the Peritoneal Cavity.

Classification of Abdominal Organs by Peritoneum Covering

1. Intraperitoneal Organs

• Definition: Organs completely surrounded by visceral peritoneum.
• Examples: Stomach, spleen, cecum, appendix, transverse colon, sigmoid colon, jejunum, ileum.

2. Mesoperitoneal Organs

• Definition: Organs covered by visceral peritoneum on three sides.
• Examples: Liver (partially due to the bare area), gallbladder, ascending and descending colon, middle rectum, urinary bladder (when full).

3. Retroperitoneal Organs

• Definition: Organs covered by visceral peritoneum on only one side.
• Examples: Duodenum, pancreas, kidneys, suprarenal glands, ureters, urinary bladder (when empty).

Relation Between Parietal and Visceral Peritoneum

• Connection: The parietal peritoneum continues to the visceral peritoneum via ligaments:
  • Falciform Ligament: Connects the liver to the anterior abdominal wall.
  • Coronary Ligament: Connects the liver to the parietal peritoneum under the diaphragm.
  • Triangular Ligaments: Right and left triangular ligaments from the liver to the diaphragm.

Omentum

Lesser Omentum

• Location: Under the liver, above the lesser curvature of the stomach.
• Components:
  • Hepatogastric Ligament: Connects liver to lesser curvature of the stomach.
  • Hepatoduodenal Ligament: Connects liver to the duodenum.

Greater Omentum

• Location: Below the greater curvature of the stomach.
• Components:
  • Gastrophrenic Ligament: Stomach to diaphragm.
  • Gastrosplenic Ligament: Stomach to spleen.
  • Gastrocolic Ligament: Stomach to transverse colon (curves around intestines).

Mesentery

• Definition: Visceral peritoneum that attaches the intestines to the posterior abdominal wall.
• Types:
  • Transverse Mesocolon: Connects transverse colon to posterior abdominal wall.
  • Mesentery of Small Intestines: Surrounds small intestines and sigmoid colon.
• Root of Mesentery: Starts at the 2nd lumbar vertebra.

Peritoneal Cavity Levels

1. Upper Level

• Components: Subphrenic recess, subhepatic recess, omental bursa (lesser sac).
  • Omental Foramen: Opening connecting greater and lesser sacs.

2. Middle Level

• Recesses:
  • Superior and Inferior Duodenal Recesses: Around duodenum and jejunum.
  • Superior and Inferior Ileocecal Recesses: Around ileum and cecum.
  • Rectocecal Recess: Behind the cecum.
  • Intersigmoid Recess: Behind the sigmoid colon.

3. Lower Level (Pelvis)

• Female:
  • Rectouterine Pouch: Between rectum and uterus.
  • Vesicouterine Pouch: Between urinary bladder and uterus.
• Male:
  • Rectovesical Pouch: Between rectum and urinary bladder.

Conclusion

• Understanding the peritoneum is crucial for grasping abdominal cavity anatomy.
• The peritoneal cavity serves as a dynamic space with various recesses and pouches that are critical for organ function and fluid movement.