My lover and I would like to experience pleasurable anal intercourse. The only previous experience I had was a painful 5 seconds, 10 years ago, when my ex-girlfriend and I hadn’t the least notion of what we were doing. Since then I’ve read several reputable sources on the subject including your book and the work of Dr. Jack Morin, and I seem to recall some advice regarding facilitation of penetration. I remember reading a recommendation somewhere that the person receiving the penis or dildo, lie on a certain side of their body in order to more easily allow for the natural curve in the sigmoid colon, where it’s attached to the rectum. Was this simply my imagination playing tricks on me? Am I getting this confused with stuff I read right before I had my first digital rectal exam and a colonoscopy? Or is there in fact a “correct” side to be lying on?
On the instructions that come with a store bought enema, one recommendation for a comfortable position (sometimes called the “Simms Position”) to give yourself an enema is to lie on your left side and bend your right leg toward your chest. This position allows easy access to the anus, keeps the weight off your abdomen, and allows the enema solution to flow easily into the colon. Likewise, often when you are given an enema from a health care professional, they may put you in that position. But I’ve never heard of a sex educator recommend that someone lie on a certain side for anal penetration.
When it comes to anal penetration with a penis or dildo, your concern is about the rectum, not the colon. The rectum is slightly curved — which is why careful penetration is important so you don’t bump into the rectal wall — but its curves are not like the more drastic curve between the rectum and the sigmoid colon. You can receive and enjoy anal penetration is many different positions, including missionary, on top, spooning, doggie style, standing, bent over something… you get the picture.
I looked in Jack Morin’s book, Anal Pleasure and Health, and the only thing he says that relates to your question is: “Any position which places your legs at right angles to the upper body . . . will straighten the rectum a bit.” Again, this comment is in reference to a discussion about the curves of the rectum, not the sigmoid colon.