Pelvic Floor Function #2: Sphincter

When I as a freshman in high school, someone had gotten their hands on a dictionary of “dirty words.” Yes, this was an actual hardbound dictionary since we didn’t have Urbandictionary.com back then. The only word I remember learning was “sphincter.” Who knew that in my professional life this would be a word I talk about all the time? And: it’s not a dirty word at all. It’s just anatomy.

Sphincters are important. You probably appreciate yours right now if you think about it: are you peeing as you read this? Are you passing stool or gas? (Disregard if you’re reading this on the toilet). If you aren’t passing any body waste, are you thinking about doing a kegel? Probably not. Pretty cool, huh? Thank your sphincters.

A sphincter is simply a round muscle. You have one around each eye, your mouth, all through your digestive system, and most importantly for this post, around your urethra and your anus.

Both the urethral and anal sphincters have 2 layers. An inner layer is made of smooth muscle—which is the kind of muscle your guts and your heart are made of. You don’t have to remember to beat your heart all day, right? (thank goodness!) And digestion goes on in the background. These are smooth muscles and are run by your autonomic nervous system. And that’s the reason we don’t typically have to think about not peeing our pants all day long. SO GREAT.

Now when you DO feel an urge come on, or you feel some gas coming while you’re in an elevator, or you’re about to sneeze—you can squeeze to hold it back. That’s the second (outer) sphincter working, and you get to control that one. When you do a pelvic floor contraction, you are squeezing the outer sphincters of both the urethra and the anus (unless you’ve been practicing and are really coordinated at squeezing one but not the other, which quite frankly I can’t think of a real good functional reason to practice).

I call this the “Sphincter function” to stick with the S-theme, but really the function of these are continence, or keeping control of your bowel and bladder. If there is weakness in these muscles, it could lead to urinary, gas, or bowel incontinence. If these muscles are too tight, it can lead to difficulty emptying the bladder or bowels. We need a balanced pelvic floor for all of it to work smoothly.

See, sphincter is not a dirty word at all. If I could go back and be my 15-year old self, I’d tell those other kids about how freaking cool sphincters are, and that they should all be grateful for them. I’m pretty sure that’d give me cool points, right? Right...

Do you think they’re cool? Have questions? Hit up the comments below!

Stay tuned for the rest of this series on the Functions of the Pelvic Floor: Sexual, Support, and Stability.