The development and structure of the mesentery

Abstract

The position of abdominal organs, and mechanisms by which these are centrally connected, are currently described in peritoneal terms. As part of the peritoneal model of abdominal anatomy, there are multiple mesenteries. Recent findings point to an alternative model in which digestive organs are connected to a single mesentery. Given that direct evidence of this is currently lacking, we investigated the development and shape of the entire mesentery. Here we confirm that, within the abdomen, there is one mesentery in which all abdominal digestive organs develop and remain connected to. We show that all abdominopelvic organs are organised into two, discrete anatomical domains, the mesenteric and non-mesenteric domain. A similar organisation occurs across a range of animal species. The findings clarify the anatomical foundation of the abdomen; at the foundation level, the abdomen comprises a visceral (i.e. mesenteric) and somatic (i.e. musculoskeletal) frame. The organisation at that level is a fundamental order that explains the positional anatomy of all abdominopelvic organs, vasculature and peritoneum. Collectively, the findings provide a novel start point from which to systemically characterise the abdomen and its contents.

The Mesentery—Past, Present, and Future

“…More recently, we built on the work of Heald and Hohenberger and clarified the shape of the mesentery, the anatomical foundation, and fundamental order of the abdomen. 5 During the journey to those discoveries, we again encountered comments that our findings were not new, and in fact were already well known. The story of the mesentery, and its application to colorectal surgery, is thus one of advancements to some and status quo to others.…”

“…We recently found that the mesentery is the organ in and on which all abdominal digestive organs develop and remain directly connected to. 5 As the abdomen develops, it remains composed of two distinct anatomical compartments. The mesenteric compartment or domain includes all abdominal digestive organs positioned on the mesentery.…”

“…This description is termed the Mesenteric Model of Abdominal Anatomy. 5,23 It explains the positional anatomy of all contents of the abdomen. In keeping with this, it explains the position of the peritoneum.…”

The Development of the Mesenteric Model of Abdominal Anatomy

“…1,2 This erroneous model of mesenteric anatomy gained wide acceptance and was unchallenged for over a century.Recent studies confirm that the mesentery below the duodenojejunal flexure is continuous to the level of the mesorectum. [3][4][5][6][7] Emerging evidence now suggests that continuity of the mesentery also applies above the duodenojejunal flexure and may extend to the level of the oesophagogastric junction. [8][9][10] This differs substantially from conventional descriptions of mesenteric anatomy, which describe the mesentery as discontinuous.Identification of mesenteric continuity has enabled division of the abdomen into two separate compartments.…”

“…Recent studies confirm that the mesentery below the duodenojejunal flexure is continuous to the level of the mesorectum. [3][4][5][6][7] Emerging evidence now suggests that continuity of the mesentery also applies above the duodenojejunal flexure and may extend to the level of the oesophagogastric junction. [8][9][10] This differs substantially from conventional descriptions of mesenteric anatomy, which describe the mesentery as discontinuous.…”