Understanding your colon or rectal surgery

The colon (large intestine) is a long, muscular tube about four to five feet long. The colon removes water and nutrients from partially digested food. Then it turns the rest into stool (waste). The stool goes through the rectum and then leaves the body through the anus.

Parts of the colon

Cecum: This is the beginning of the colon. It is located in the lower right side of the abdomen.

Ascending colon (right colon): This is the first part of the colon.

Transverse colon: This is the middle part of the colon.

Descending colon (left colon): This is the third part of the colon.

Sigmoid colon: This is the last part of the colon.

Rectum: The stool goes through the rectum. The rectum ends at the anus.

Anus: This is the opening at the end of the colon. Stool leaves the body through this opening.

The rectum and anus have muscles and nerves that control bowel movements.

Blood supply to the colon

There are three main arteries that supply (give) blood to the colon.

  • The ileocolic artery supplies blood to the first part of the colon.
  • The middle colic artery supplies blood to second part of the colon.
  • The inferior mesenteric artery supplies blood to the third part of the colon.

There are also veins that go with each of these arteries.

Lymph nodes

Lymph nodes act like filters that remove dead cells, bacteria (germs) and even cancer cells from the body and keep them out of the bloodstream. They are found near the arteries and veins of the colon.

You may need to have lymph nodes removed. If cancer is found in the colon, the lymph nodes can be tested for cancer cells. This will help decide the stage of cancer and if more treatment is needed.

Source: Allina Health's Patient Education Department, Understanding Your Colon or Rectal Surgery, second edition, can-ah-95399
Reviewed By: Johan Nordenstam, MD, MS, PhD
First Published: 01/24/2013
Last Reviewed: 07/15/2015

diagram showing colon parts