Low Rectal Cancer
Your Cancerous Rectum
The rectum is at the end of the food path between the mouth and the toilet. It has a special function. The rectum is the area where feces is stored until it is socially acceptable to expel it into a toilet. As the semi solid feces moves into the rectum, it contacts the nerves that surround the anus. You sense that the rectum is full when you feel this sensation and make a decision if you want to go to the toilet. If you cannot get to a toilet you tighten the voluntary muscles around the anus and the feces is retained until you can get to the toilet. If you can get to the toilet, you sit down and intentionally relax the voluntary muscles that surround the anus. The relaxation allows the anus to open and the muscles in the rectum contract and push the feces out of the rectum into the toilet. The rectal muscles totally empty the rectum of feces. You will not feel the urge to go to the toilet until the rectum again fills and the feces contacts the sensitive anal nerves.
The rectum is not just the end of the colon. Because its role is to store stool until it is socially acceptable to empty it into the toilet, it has more volume per length than the rest of the colon and it is also more muscular. The surgical practice of creating a J-Pouch by folding back a section of the colon does not make a new rectum. The J-Pouch may have more volume per length than the colon but it does not have the muscular structure needed for evacuation. In addition, the pouch is more difficult to evacuate because there is more volume of stool stored in the pouch that has a limited ability to empty.
Anorectal Anatomy Medical drawings of the rectum
Anatomy - Anus and Rectum A very detailed medical description of the rectum