Anal anatomy may not be the most glamorous topic but it's well worth knowing your way around.
The anus is made of two rings of muscle, and it’s about 1-1.5” (2.5-4cm) long. The external muscle is the first one that you would come to if you were touching somebody, inserting a toy, or a finger. This is skeletal muscle, which is the kind of muscle you can deliberately control. For instance, when you contract your arm muscles, you move your arm bones, which is why it’s called skeletal muscle. Most people can squeeze and relax the external muscle.
The internal anal muscle is “smooth muscle.” This is the kind of muscle in your blood vessels, your organs, and in the iris of your eyes. It’s controlled by the part of your nervous system that manages all the things you don’t really think about much, like your heart rate or how fast you’re breathing. That’s important because it means that while you have some influence over it, you don’t have control.
For example, if someone tells you to take a deep breath, you can probably do that. But most of the time, you don’t pay much attention to it. And if you’re worried, it’s a lot harder to take that deep breath because your nervous system is responding to the stress.
The internal anal muscle does much the same thing. If you’re worried, angry or stressed out, the pelvic floor and the internal anal muscle tighten up. It’s the same reflex that makes a scared cat or dog tuck their tail between their legs. And it’s the reason that someone who’s angry all the time is sometimes called a “tight ass.” It’s literally true.
This week's topic is Anal Anatomy, follow these links to read the rest of the series!
Part 1 - Two Rings of Muscle
Part 2 – The Physical Response to Stress
Part 3 – Taking Care of the Skin
Part 4 – Learning to Relax