mesocolic

Mesocolic refers to anything relating to the mesocolon, a peritoneal fold that attaches portions of the large intestine to the posterior abdominal wall. The mesocolon forms a mesentery for the colon and is described for the ascending, transverse, descending, and sigmoid segments. It carries vessels, nerves, and lymphatics that supply and drain the colon and helps anchor the bowel while allowing limited mobility.

Anatomy and content: Each mesocolon contains arterial branches (such as those from the superior or inferior mesenteric arteries, including the middle, left, and right colic arteries), their accompanying veins, autonomic nerves, and lymphatics. The mesocolon thus provides a conduit for essential blood supply and drainage and for neural and lymphatic pathways to regional lymph nodes.

Development and variants: The mesocolon arises from peritoneal reflections during embryonic gut rotation and fixation. Variations in fixation and mesenteric length influence colonic mobility and can lead to clinical conditions such as mesocolic hernias or, rarely, mesocolic volvulus, in which a segment of colon twists around its mesocolon.

Clinical relevance: In colorectal surgery, the concept of complete mesocolic excision emphasizes removing the colon with an intact mesocolic envelope along embryological planes, along with associated lymph nodes. Adherence to these planes aims to improve oncologic outcomes by ensuring a thorough, en bloc resection of the tumor and its mesocolic tissues. Mesocolic involvement on imaging or pathology can have prognostic significance in colon cancer.

See also: Mesentery, Peritoneum, Colon, Colic arteries.