Difference Between Peritoneum and Omentum

The key difference between peritoneum and omentum is that peritoneum is a glistening, transparent, serous membrane that lies surrounding the abdomino-pelvic cavity, while omentum is a projection of the peritoneum.

Peritoneum and omentum primarily contribute to the anatomy of the gut. They are important in the mechanical digestion process that takes place in the stomach. Additionally, they also have secretory functions that regulate metabolic processes.

CONTENTS

1. Overview and Key Difference
2. What is Peritoneum 
3. What is Omentum
4. Similarities Between Peritoneum and Omentum
5. Side by Side Comparison – Peritoneum vs Omentum in Tabular Form
6. Summary

What is Peritoneum?

Peritoneum lines the abdomino-pelvic cavity of the internal viscera and supports and covers most of the abdominal organs. Moreover, it acts as the main conduit for the associated lymph vessels, nerves, and abdominal arteries and veins. It is a glistening, transparent, serous membrane. The peritoneum consists of two layers: the parietal peritoneum and the visceral peritoneum. The parietal peritoneum is well vascularized. Furthermore, it receives a good supply of lymph. Somatic nervous supplies nerves to the peritoneum.

The peritoneal walls are sensitive to pressure, heat, pain and cold. In contrast, the visceral peritoneum receives nerve impulses from the visceral nervous supply. It is not sensitive to stimuli such as heat, cold, touch and laceration. However, it responds to stretching and chemical stimuli.

What is Omentum?

Omentum is a double layer extension of the peritoneum. Omenta resemble folds-like structures in the stomach. The omentum extends across the stomach to the proximal part of the duodenum. It divides into two parts structurally. They are the greater omentum and the lesser omentum.

The greater omentum forms the prominent folds in the stomach. They have a greater curvature. Moreover, they are large in size, fat-laden and prevent the visceral peritoneum from adhering to the parietal peritoneum. The greater omentum connects the greater curvature of the stomach to the duodenum. Furthermore, there is considerable motility in the greater omentum. Movement takes place through peristalsis. The greater omentum also has a protective role during appendicitis. It forms a protective covering surrounding the inflated appendix. Thus, it protects the effect of the inflated appendix on other tissues.

In contrast, the lesser omentum has lesser curvature and is small in size. It connects the lesser curvature of the stomach to the proximal part of the duodenum. Omentum has the ability to secrete adipokines such as omentin, which act as a biomarker of obesity and metabolic syndrome.

What are the Similarities Between Peritoneum and Omentum?

• Peritoneum and omentum are present in the abdomino-pelvic cavity.
• Both provide anatomical modifications for the gut structure.
• Also, they participate in the mechanical digestion process.
• Moreover, there is a good supply of blood and lymph in both structures.

What is the Difference Between Peritoneum and Omentum?

The peritoneum and the omentum surround the gut. The peritoneum covers the abdomino pelvic cavity while omentum forms fold in the peritoneum, lining the stomach and the duodenum. So, the key difference between peritoneum and omentum is their location. Furthermore, the peritoneum receives nerve supply from the visceral nerves, whereas the omentum receives nerve supply from the somatic nerves. Therefore, this is another difference between peritoneum and omentum.

The below infographic summarizes more information regarding the difference between peritoneum and omentum.

Summary – Peritoneum vs Omentum

Peritoneum and omentum are important anatomical structures of the gut plan. The peritoneum is a serous membrane that lines the abdomino-pelvic cavity and supports and protects abdominal organs. Omentum, on the other hand, is a fold of the peritoneum. Omenta form connections between the stomach and the duodenum. Peritoneum divides further as the visceral peritoneum and the parietal peritoneum. In contrast, omentum divides as greater omentum and the lesser omentum based on the curvature size. Moreover, both have secretory functions. Thus, this summarizes the difference between peritoneum and omentum.

Reference:

1. “Peritoneum, Mesentery, and Omentum.” Vivo Pathophysiology, Available here.

Image Courtesy:

1. “Lesser omentum EN” By Olek Remesz (wiki-pl: Orem, commons: Orem) – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Gray1035” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body (See “Book” section below)Bartleby.com: Gray’s Anatomy, Plate 1035 (Public Domain) via Commons Wikimedia