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Transverse mesocolon

The transverse mesocolon is a broad, double-layered peritoneal fold that suspends the transverse colon from the posterior abdominal wall. It extends horizontally across the abdomen, attaching the transverse colon to the posterior parietal peritoneum along the anterior border of the pancreas.

Within its two layers run the middle colic vessels (artery and vein), lymphatics, autonomic nerves, and fat. It is continuous superiorly with the posterior layer of the greater omentum and inferiorly blends with the mesentery of the small intestine. The transverse mesocolon plays a key role in organizing the peritoneal cavity into supracolic and infracolic compartments, influencing the spread of infections and fluids.

Clinically, the transverse mesocolon is important in colon resections, mesenteric ischemia, inflammatory disease, and tumor spread. It is also an important surgical landmark in procedures involving the pancreas and transverse colon.

Synonyms

  • Mesocolon transversum

  • Mesentery of the transverse colon

Function

  • Suspends the transverse colon and maintains its anatomical position

  • Conveys the middle colic vessels, lymphatics, and autonomic nerves

  • Separates peritoneal cavity into supracolic and infracolic compartments

  • Provides a pathway for the spread of disease and surgical access

Nerve Supply

  • Derived from autonomic fibers accompanying middle colic vessels via the superior mesenteric plexus

Arterial Supply

  • Middle colic artery (branch of the superior mesenteric artery) supplies the transverse colon through the transverse mesocolon

  • Anastomoses with right colic and left colic arteries via the marginal artery of Drummond

Venous Drainage

  • Middle colic vein drains into the superior mesenteric vein, contributing to the portal venous system

MRI Appearance

T1-weighted images:

  • Appears as a fatty peritoneal fold of high signal intensity containing intermediate-signal vascular structures

  • Colon wall is intermediate signal, making vessels within mesocolon distinguishable

T2-weighted images:

  • Appears as a fatty peritoneal fold of high signal intensity containing intermediate-signal vascular structures

  • Colon wall is intermediate signal, making vessels within mesocolon distinguishable

  • Mesenteric fat: Hyperintense (bright) on conventional T2 FSE/HASTE without fat suppression.

  • Vessels: Appear as flow voids coursing within the fatty mesocolon.

  • Edema/inflammation (“stranding”): Hyperintense linear/patchy signal superimposed on bright fat; becomes even more conspicuous on fat-suppressed T2.

  • Fluid collections/abscess: Very high T2 signal fluid; abscess may show a T2-hypointense rim.

  • Colon wall: Mural edema hyperintense; may show layered/“target” appearance in colitis or ischemia.

  • Lymph nodes/solid implants: Intermediate T2 signal relative to fat (stand out against bright background).

STIR:

  • Suppresses fat, making vascular structures and inflammatory changes more conspicuous

  • Useful in identifying fluid tracking, abscesses, or edema in mesocolon

T1 Fat-Saturated (Pre-contrast):

  • Mesocolic fat suppressed; vessels appear as intermediate signal lumens

  • Helps separate vascular structures from fat planes

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Middle colic vessels enhance brightly

  • Highlights mesenteric inflammation, tumor infiltration, or vascular abnormalities

MRI Non-Contrast 3D Imaging:

  • Provides 3D mapping of the vascular arcades within the transverse mesocolon

  • Useful for preoperative planning, vascular mapping, and tumor staging

CT Appearance

CT Pre-Contrast:

  • Mesocolon appears as a fat-density fold connecting transverse colon to posterior abdominal wall

  • Vessels and lymph nodes visible as soft-tissue densities

CT Post-Contrast:

  • Middle colic vessels and tributaries enhance brightly

  • Detects lymphadenopathy, vascular invasion, ischemia, or inflammatory changes

  • Important for staging colon cancer, pancreatitis spread, or mesenteric ischemia

MRI images

Transverse mesocolon MRI coronal image anatomy image -img-00000-00000

MRI images

Transverse mesocolon MRI sagittal image anatomy image -img-00000-00000

CT images

Transverse mesocolon axial ct image

CT images

Transverse mesocolon CT coronal image