When you eat, food travels over 15 feet before leaving your body! But before it leaves, it has two final stops; the rectum and the anal canal. Let’s explore these gastrointestinal organs of the pelvis and discuss the process of defecation and the structures involved.

The rectum is the terminal chamber of the large intestine that temporarily stores feces before defecation. The rectum joins with the sigmoid colon at the level of S3, forming the rectosigmoid junction.

Then, the rectum courses below in the pelvic cavity, reaching a point anterior and inferior to the tip of the coccyx. Here, the rectum pierces the levator ani muscle to join with the anal canal, forming the anorectal junction.

Let’s think of the pelvis like a bowl. The levator ani muscle acts as the bottom of the bowl to support the structures within the pelvis, especially the rectum.

Another structure that supports the rectum is the anococcygeal ligament which forms a fibrous ridge from the anal canal to the coccyx, acting as an anchor.

The relations of the rectum to the surrounding structures differs between biologically male and biologically female individuals.

In males, the rectum lies behind the fundus of the urinary bladder, the seminal vesicles, the left and right ductus deferens, and the prostate gland. In females, the rectum lies behind the lower end of the uterus and the vagina.

The rectum is a Latin word that means straight, but this is a bit misleading, because the human rectum actually has many flexures.

These flexures include the sacral, the anorectal, and the superior, inferior, and intermediate lateral flexures. The sacral flexure follows the curve of the sacrum and the coccyx, forming an anteroposterior curve with an anterior concavity.