Root of mesentery

The root of the mesentery is the narrow, fixed origin of the mesentery on the posterior abdominal wall

• Shape and Length: The root is short, typically about 15-20 cm long in large animals, but varies by species.

• Location: It is attached to the dorsal abdominal wall, just ventral to the first lumbar vertebra, usually to the left of the midline.

• Direction: It extends obliquely downward and to the right, from the cranial mesenteric artery origin (just caudal to the celiac artery) toward the ileocecal junction in most species.

Structures associated with the root of the mesentery:

Cranial Mesenteric Artery (CMA)

• The principal blood supply to the small intestines and parts of the large intestine.

• Originates from the abdominal aorta just caudal to the celiac artery.

Mesenteric Vein

• Drains blood from the intestines to the portal vein and subsequently the liver.

Lymphatics and Lymph Nodes

• Numerous jejunal and mesenteric lymph nodes are embedded in the mesentery near its root, important for immune surveillance.

Autonomic Nerves

• The mesenteric plexus (part of the autonomic nervous system) surrounds the CMA, carrying both sympathetic and parasympathetic fibers.

Embryological Basis

The root corresponds embryologically to the area where the dorsal mesentery attaches to the primitive gut tube. Rotation and elongation of the midgut during development result in the spiral orientation of the intestines around this central root.