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The peritoneum is a thin membrane that separates the intra-abdominal contents, helping to support them and also allow blood and lymph vessels to pass. 

Gross Anatomy

It consists of 2 layers, the parietal and visceral peritoneum. The parietal peritoneum lines the internal surface of the abdominal cavity and the visceral peritoneum lines the intra-abdominal viscera; however it is a continuation of the parietal peritoneum. Some organs are classed as retroperitoneal structures, that is to say that they have only an anterior surface covering of peritoneum. Examples of these include the kidneys and aorta.


The peritoneum forms double layered folds called mesentery. It most commonly relates to the small bowel from which it is the source of its lymph and blood supply but is also found on other organs such as the appendix and sigmoid colon, for example.


The peritoneum forms the omentum, a 4 layer fold of peritoneum. The greater omentum extends for the greater curvature of the stomach and proximal duodenum, then folds back on itself to insert onto the transverse colon.


It also forms the lesser omentum, which extends from the liver to the lesser curvature of the stomach and first part of the duodenum. It has a free border which contains the common bile duct, hepatic artery and portal vein.


Behind the lesser omentum is the lesser sac. On the left it is bounded by the gastrosplenic and lienorenal ligaments. On the right it communicates with the greater sac via the epiploic foramen. Its boundaries are outlined below.


Boundaries of the epiploic foramen


The free border of the lesser omentum


Inferior vena cava




Caudate process of the liver

Clinical Anatomy

Pain in appendicitis


The nerve supply of the parietal and visceral peritoneum also differs slightly. The parietal peritoneum is innervated by somatic fibres that also supply the abdominal wall, however the visceral peritoneum is dependent on its corresponding viscera so is poorly localised. Hence why in appendicitis the pain classically localises later in the disease to the right iliac fossa due to late parietal irritation as compared to early poorly localised visceral peritoneal inflammation.


Pringle’s manoeuvre


During liver surgery if there is damage to the hepatic artery or portal vein it can be controlled via compression at the free border of the lesser omentum. This is known as Pringle’s manoeuvre.

Quick Anatomy

Key Facts

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Retroperitoneal organs:


SADPUCKER- Suprarenal glands, Aorta, Duodenum, Pancreas (not the tail), Ureters, Colon (ascending and descending) Kidneys, Oesophagus, Rectum


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Gosling et al. Human Anatomy.  Fourth Edition. Mosby Publishing 2002

Dean & Pegington. Core Anatomy for Students. Volume 2: The Thorax, Abdomen, Pelvis & Perineum. Saunders. Elsevier Science. 2002

S Jacob. Atlas of Human Anatomy Second Edition. Elsevier 2005