Last revised by Dr Daniel J Bell on 13 Dec 2021

The peritoneum (rare plural: peritonea or peritoneums) is a large complex serous membrane that forms a closed sac, the peritoneal cavity, within the abdominal cavity. It is a potential space between the parietal peritoneum lining the abdominal wall and the visceral peritoneum enveloping the abdominal organs. In females, this closed sac is perforated by the lateral ends of the fallopian tubes

Gross anatomy

The peritoneum is made up of a single layer of mesothelial cells supported by connective tissue. The free surface of the peritoneum bears the mesothelial cells and is kept moist and smooth by a thin film of serous fluid. The potential peritoneal spaces, the peritoneal reflections forming peritoneal ligaments, mesenteries and omenta, and the natural flow of peritoneal fluid determine the route of spread of intraperitoneal fluid and disease processes within the abdominal cavity.

It can be divided into two main compartments that are separated by the root of the transverse mesocolon: the supramesocolic space above, and the inframesocolic space below.

The peritoneal cavity can also be divided into a greater sac (which is usually used synonymously with the peritoneal cavity) and a lesser sac, which lies posterior to the stomach. 


  • parietal peritoneum: supplied segmentally by the spinal (intercostal and lumbar) nerves innervating the overlying muscles
  • diaphragmatic (parietal) peritoneum: supplied by the phrenic nerve (C3, C4, C5 roots), hence referred pain from the diaphragm is felt at the tip of the shoulder
  • visceral peritoneum: no afferent supply, pain from diseased viscera is due to muscular spasm, tension on mesenteric folds or involvement of the adjacent parietal peritoneum
  • mesenteric root: possesses numerous Pacinian corpuscles (mechanoreceptors) which serve a protective function, by causing the reflex contraction of abdominal muscles to support the abdominal viscera during jarring movements of the abdomen which may cause undue traction on associated peritoneal attachments

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Cases and figures

  • Figure 1: peritoneal cavity
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  • Figure 2: mesentery (sagittal)
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