The ascending colon is the first portion of the colon, and it is around 5.91 to 7.87 inches (15 - 20 cm) long. It is found on the right side of the abdominal cavity. The ascending colon starts above the ileocecal junction as a continuation of the cecum.

From the cecum, the ascending colon extends in the superior direction toward the right lobe of the liver. Upon reaching the liver, it makes a sharp turn to the left side, creating a flexure known as the right colic (hepatic) flexure. This flexure marks the junction between the ascending colon and the next part of the colon - the transverse colon.

The ascending colon lies retroperitoneally, and the peritoneum covers it from the anterior and lateral aspects. Besides the peritoneum, the ascending colon is related to various other structures. The iliac fascia, quadratus lumborum muscle, iliolumbar ligament, transversus abdominis muscle, and renal fascia lie posterior to it.

In addition, posterior to the right colic flexure lies the inferior aspect of the right kidney. The posterior aspect of the right colic flexure is not covered by the peritoneum. Therefore, it is in direct contact with the renal fascia. The right lobe of the liver is located superiorly, the fundus of the gallbladder lies anteromedially, and the descending part of the duodenum is situated medially to the right colic flexure.

Note: On both sides of the abdominal cavity are two deep vertical recesses called paracolic gutters. The right paracolic gutter is located between the lateral surface of the ascending colon and the lateral abdominal wall. Similarly, on the left side, between the lateral aspect of the descending colon and the lateral abdominal wall, lies the left paracolic gutter. These vertical recesses are basically free interconnected abdominal cavity spaces.

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Ascending colon