Transverse colon

The transverse colon is the longest and most mobile part of the large intestine. It measures up to 45 cm in length. 

Gross anatomy

The transverse colon is the continuation of the ascending colon from the right colic flexure. It passes from the right to left hypochondrium in a downward convex path crossing both the epigastric and umbilical zones. In the left hypochondrium, it curves sharply on itself beneath the lower end of the spleen, forming the left colic flexure where it continues as the descending colon.

It is almost completely invested by peritoneum, and is connected to the inferior border of the pancreas by a large and wide duplicature of that membrane, the transverse mesocolon. The gastrocolic ligament also attaches the transverse colon to the stomach. The phrenicocolic ligament attaches to the left colic flexure and connects it to the diaphragm, with variable connection to the inferior aspect of the spleen.

Relations

• superiorly (right to left): liver, gallbladder, greater curvature of the stomach, spleen

• inferiorly: small bowel 

• anteriorly: greater omentum and anterior abdominal wall

• posteriorly (right to left):  2nd part duodenum, head and body of pancreas, small bowel

Arterial supply

• middle colic artery (branch of superior mesenteric artery) supplies proximal 2/3two-thirds

• ascending branch of left colic artery (branch of inferior mesenteric artery) supplies distal 1/3one-third

Venous drainage

• via similarly named veins to splenic vein to the portal venous system

Innervation

• sympathetic: superior mesenteric plexus and inferior mesenteric plexus

• parasympathetic: derived from pelvic splanchnic nerves (S2-S4)

Lymphatic drainage

Lymphatics accompany vessels and drain to paracolic nodes, and to the superior mesenteric group (proximal two-thirds) and inferior mesenteric group (distal two-thirds).

Radiographic features

Fluoroscopy

Double contrast barium enemas provided good anatomical detail from the rectum to the caecum. The patient may need to be rolled into various positions to get the barium sulfate contrast medium to coat the lumen of the colon. 

see also

• ascending colon

• descending colon

• sigmoid colon