One of the best books out there for describing the physiology of the anus, rectum and lower intestines is the book Anal Pleasure and Your Health by Jack Morin, PhD.  Knowing just what is up there and then going in yourself with fingers to see just how everything is placed is essential to playing with the least amount of risk for injury. It has been an invaluable resource for me in the discovery of my own hole and understanding others’.

The Sphincters

What most people don’t realize is that there are actually two outer sphincters composed of separate rings of muscle, one is called the external, the other internal. You can actually feel them both with your finger if you know they are there.

The external one is the one you can loosen or tighten at will, the internal is part of the autonomous nervous system and the reason why your hole stays closed even when you’re not focused on it. The latter requires practice and meditative relaxation to learn to ‘control’.

Contrary to common belief it is not the sphincter that is primarily responsible for helping maintain continence (control over bowel movements). Hence, the urban legend believed by many not into butt play of guys and gals having to eventually wear diapers is not founded in fact. Playing with your hole and stretching it will NOT make you incontinent. Damaging the Pubo-rectalis (next section), can.

The section of colon immediately inside the sphincter is called the rectum and is there to absorb any last bits of moisture. It’s therefore important to think about what kind of toys, chemicals and lubes you put up there, since it will most likely find its way immediately into your bloodstream.

The Pubo-Rectalis … what some call the Second Sphincter

Although you can have feces in your rectum, the bulk of it is usually held back by what Morin refers to as the ‘pubo-rectal sling’, in America known as the Pubo-rectalis. It is a loop of muscle attached to the pubic bone at both ends and embedded within a whole sheet of muscles within the cavity of the pelvis which wraps around the intestine to form what is essentially the boundary between the rectum and the sigmoid colon.

A lot of people commonly refer to this as the ‘Second Sphincter’, some say the ‘Third Sphincter’ depending whether you count the anus as having 1 or 2. Clever and confusing but the pubo-rectalis isn’t a sphincter at all. Calling it a sphincter is pretty natural when you consider that it functions much like our idea of one, and even delivers feelings like the asshole does when it is manipulated in a particular way, this I can personally attest to.

On those lucky occasions when I have been able to take a fist past this point, or when I play with certain toys deep, during the withdrawal it can feel as though the hand or toy comes out of me twice. Once, I wasn’t watching the action ‘down below’ and at one point I had thought that my partner had completely come out of me. When I realized he was still pulling I looked down and saw he was still in about to the mid forearm. It was the second sphincter that had produced those feelings in me. But, caution must always be exercised when going this deep inside, choose your partner wisely and don’t pressure yourself, or let others pressure you to do it.

In the beginning, I believe to go that deep is something that must just happen when all the pieces fall into place. Trying to force this next level of play on yourself is not wise. Once this has happened and the door is open, you can begin to actively explore the depths. When people complain of a pain inside while either being fucked or playing with toys it is most likely the pubo-rectalis that has not relaxed or is in a position to prevent opening. Sometimes I have felt a snapping feeling inside like a rubber band, which I often attributed to this muscle. Though, if snapping is what you are feeling it is most likely not a good thing.

Since they are both on the autonomous nervous system the pubo-rectalis and the internal sphincter, respond to and store up stress. Uptight people have rightly earned the designation ‘anal-retentive’ for this reason. But through focused relaxation one can learn to ‘control’ these muscles somewhat. So needless to say that, in the long run, peace of mind and good relaxation techniques are as essential to a happy hole and productive playtime as anything else.