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# Mesocolon

The mesocolon is the fold of tissue that attaches parts of the colon (large bowel) to the back wall of the [abdomen](https://durgical.com/en/anatomy/region/abdomen/) and carries its vessels and lymph nodes.

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## What it is

Folds of [peritoneum](https://durgical.com/en/anatomy/peritoneum/) attaching parts of the colon (transverse and sigmoid) to the back wall.

## What it does

Carry the colic vessels and nodes; in a colectomy the surgeon removes the colon with its mesocolon.

## Key points

- In colon cancer surgery the colon is removed inside its intact mesocolon, with the central vessels and lymph nodes (complete mesocolic excision)
- The bloodless fusion plane (Toldt fascia) between the mesocolon and the retroperitoneum (renal fascia, ureter, gonadal vessels, [duodenum](https://durgical.com/en/anatomy/duodenum/)) is the plane followed in a colectomy
- The intersigmoid recess at the apex of the sigmoid mesocolon lies over the left ureter, a surgical landmark

## Key facts

**Where**
Transverse mesocolon and sigmoid mesocolon; ascending and descending mesocolon are fused to posterior wall (secondarily retroperitoneal)

**Attaches**
Transverse: root along anterior border of pancreas; sigmoid: inverted-V root with apex over left ureter at common iliac bifurcation

**Function**
Carry colic vessels, nodes and nerves; transverse mesocolon divides supracolic from infracolic compartment

## Relations

**Contents**
[Colic arteries](https://durgical.com/en/anatomy/right-colic-artery/) and veins, the marginal artery, the lymph nodes draining the colon and autonomic nerves

**Behind**
Transverse mesocolon: D2 and the head and body of the [pancreas](https://durgical.com/en/anatomy/pancreas/) at its root; sigmoid mesocolon: left [ureter](https://durgical.com/en/anatomy/ureter/), iliac vessels and gonadal vessels

**Above**
Above the transverse mesocolon: the lesser sac and the [stomach](https://durgical.com/en/anatomy/stomach/); it forms part of the floor of the lesser sac

**Below**
Below the transverse mesocolon: the small intestine in the infracolic compartment

## How to find it

At laparotomy the [transverse colon](https://durgical.com/en/anatomy/transverse-colon/) is lifted to show the transverse mesocolon from below with the middle colic vessels; the sigmoid loop is lifted to show its mesocolon and the intersigmoid recess.

## On imaging

On CT the mesocolon is fat crossed by the colic vessels; stranding there follows colitis, diverticulitis or pancreatitis, and a whirl of twisted mesenteric vessels (whirl sign) suggests volvulus.

## Common problems

- Peritonitis: infection or inflammation, usually from a burst organ ([appendix](https://durgical.com/en/anatomy/vermiform-appendix/), ulcer); severe pain and a rigid abdomen. An emergency.

## How it is diagnosed

Examination, blood tests, CT.

## Treatment

- Treat the source (often surgery) and antibiotics.

## Clinical notes

- Pancreatitis and pancreatic cancer can spread into the transverse mesocolon and involve the middle colic vessels
- Sigmoid volvulus twists on a long sigmoid mesocolon with a narrow root
- In some gastric and biliary operations a jejunal loop is brought up through a window in the transverse mesocolon (retrocolic route)

## Development

The colon starts with a continuous dorsal mesentery; after the gut rotates, the ascending and descending mesocolons fuse with the posterior wall, leaving the fusion fascia that surgeons separate.

## Related conditions

- [Sigmoid volvulus](https://durgical.com/en/conditions/sigmoid-volvulus/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which parts of the colon have a free mesocolon?

The transverse and sigmoid colon; the ascending and descending mesocolon are fused to the posterior wall (secondarily retroperitoneal).

## What important structure lies under the apex of the sigmoid mesocolon?

The left ureter, at the common iliac bifurcation, under the intersigmoid recess: a surgical landmark.

## What is complete mesocolic excision in colon cancer surgery?

Removing the colon inside its intact mesocolon, with the central vessels and lymph nodes, along the bloodless fusion plane (Toldt fascia).

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
mesocolon TA2 3744

**Official Spanish (DeCS)**
Mesocolon DeCS D008646

**English (TA2)**
Mesocolon

Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=8822); [Anatomy, Abdomen and Pelvis: Large Intestine](https://www.ncbi.nlm.nih.gov/books/NBK470577/).

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Source: https://durgical.com/en/anatomy/mesocolon/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/mesocolon/