Defining the Root of the Abdomen
While not a standard anatomical term, the 'root of the abdomen' refers to the root of the mesentery. The mesentery is a double layer of peritoneum that attaches the small intestine (specifically the jejunum and ileum) to the back (posterior) abdominal wall. This attachment point serves as the 'root' from which the mesentery supports the digestive organs.
Historically seen as separate tissues, the mesentery was confirmed as a single, continuous organ in 2016 following research by colorectal surgeon J. Calvin Coffey. This reclassification has increased understanding of its functions beyond structural support.
The Anatomical Path of the Mesenteric Root
Measuring about 15 cm, the mesenteric root is shorter and narrower than the intestinal attachment of the mesentery. It follows a specific, oblique path across the posterior abdominal wall, extending from the duodenojejunal flexure on the left to the ileocecal junction on the right. Along its diagonal route, the root of the mesentery crosses several retroperitoneal structures. These include parts of the duodenum, the abdominal aorta and inferior vena cava, the right ureter, the right psoas major muscle, and the right gonadal artery. This location makes the mesenteric root an important anatomical landmark in medical imaging and surgery.
Functions Beyond Anchorage
The mesentery performs multiple vital functions as an active organ. It provides a pathway for blood vessels, nerves, and lymphatic vessels that serve the intestines. It also plays a role in the immune system by containing lymph nodes important for monitoring the gut environment. Mesenteric fat tissue is metabolically active.
Mesentery vs. Omentum
Both are peritoneal folds with different locations and functions. The mesentery connects the intestines to the posterior abdominal wall, while the omentum hangs from the stomach and transverse colon. Their functions also differ; the mesentery anchors intestines and provides neurovascular pathways, while the omentum protects organs and stores fat.
Clinical Significance and Conditions
Disorders involving the mesentery can be serious due to its connection to intestinal blood supply. An abnormally short mesenteric root can lead to intestinal twisting (volvulus). Blockages in mesenteric vessels can cause mesenteric ischemia. Inflammatory bowel diseases like Crohn's often involve the mesentery, and mesenteric panniculitis is an inflammatory condition affecting mesenteric fat.
The Importance of the Mesentery in Surgery
Modern surgery recognizes the mesentery as a single entity. Procedures for abdominal cancers, such as total mesocolic excision (TME) for colon cancer, involve removing the tumor and its associated mesentery to improve outcomes.
Conclusion
The root of the abdomen is the anchoring point for the mesentery, a vital organ for digestive health. This structure provides a pathway for essential blood vessels, nerves, and lymphatics serving the intestines and is crucial for metabolic, immune, and structural support. The reclassification of the mesentery has led to improved surgical techniques and a deeper understanding of its role in various diseases, highlighting its importance in overall health.
