Ascending colon

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Divisions, features, neurovasculature and lymphatic drainage of the large intestine.

The ascending colon is the second part of the large intestine. 

The ascending colon passes superiorly on the right side of the abdominal cavity. It extends from the cecum to the right lobe of the liver, where it turns left at the right colic flexure, also known as the hepatic flexure. This flexure lies beneath the 9th and 10th ribs and is partially covered by the inferior part of the liver.

The ascending colon is comparatively narrower than the cecum and is considered retroperitoneal as it runs along the right side of the posterior abdominal wall. 

The greater omentum creates a division between the anterolateral abdominal wall and the ascending colon. Along the lateral aspect of the ascending colon and the neighboring abdominal wall, a vertical groove lined with parietal peritoneum is formed, known as the right paracolic gutter.

The arterial supply to the ascending colon arises from branches of the superior mesenteric arteries. This includes the ileocolic artery and right colic artery. These arteries anastamose with each other and then with the right branch of the middle colic artery. This forms a series of anastomotic arcades. These arcades, along with the left colic artery and sigmoid artery, create a continuous arterial channel known as the marginal artery. The marginal artery runs parallel to and alongside the colon, facilitating efficient blood supply to these regions.

Venous drainage from the ascending colon flows through the ileocolic vein and right colic vein. These are tributaries of the superior mesenteric vein.

The lymphatic drainage of the ascending colon starts at the epicolic and paracolic lymph nodes then to the ileocolic and intermediate right colic lymph nodes. Finally, the drainage leads to the superior mesenteric lymph nodes.

The ascending colon is innervated by the by the superior mesenteric nerve plexus.