Anatomy of the Mesentery.

It is clear that despite the importance of multimodal therapy, the most impactful weapon in the arsenal of treatment in a patient with colorectal cancer is high-quality surgery. This has been shown time and time again and surgery remains the bedrock in the management of visceral, and particularly colorectal, cancer. The reason for this is an anatomical one, based upon embryological planes. One cannot truly understand and perform high-quality surgery without an appreciation of the fascial and mesenteric anatomy of the abdomen and pelvis. R. J. ("Bill") Heald greatly advanced the management of rectal cancer with his description of the anatomical foundation of total mesorectal excision. He popularized usage of the term "mesorectum" and was an early pioneer in the commitment to mesenteric-based surgery. This concept has been extended by Werner Hohenberger to mesocolic excision for colon cancer surgery. These all rely on the principle that, in general, cancer tends to remain within its embryological compartment of origin, making it amenable to dissecting out as an oncological surgical envelope or package. There have been some theories put forth as to why, but it remains the fact that, far more often than not, an excision within the mesenteric plane affords better outcomes than the one that breaches it. Thus an understanding of the anatomy of the mesentery is important and is the scientific foundation of the art that is cancer surgery. Herein the author outlines the history of the development of our understanding of mesenteric anatomy and where we are today.