Structure
The omentum apron is the free hanging portion of the greater omentum. It consists of adipose (fat) tissue and other loose connective tissue and is the largest mesentery tissue by length and width.
Anatomical Relations
The omentum apron is unique compared to other mesenteries within the peritoneal cavity as it consists of four layers since this double layered sheet of tissue folds under itself. It’s also the mesentery that occupies the most anterior portion of the peritoneal cavity, which is why it's typically the first tissue to be identified in open abdominal surgeries.
The main points of attachment are from the greater curvature of the stomach and the inferior first portion of the duodenum to the posterior abdominal wall slightly superior to the transverse colon.
The course of the omental apron begins at its attachment along the stomach and duodenum, where it's continuous with the visceral peritoneum. From there, the anterior portion of the greater omentum descends inferiorly to variable locations within the peritoneal cavity. Then the anterior sheet turns posteriorly on itself to run superiorly as the posterior sheet, where it will eventually attach to the posterior abdominal wall superior to the transverse colon. This is why the omentum apron is described as consisting of four layers, and not the typical two layers of all other mesenteries.
Function
The greater omentum has two main functions:
- reabsorption of the peritoneal fluid;
- a high concentration of macrophages and other lymphoid tissue within the greater omentum illustrates its importance for destroying pathogens and the ability to quickly launch an immune response in the peritoneal cavity if necessary.
