There are about 300 skeletal muscles in the human body. Sort of. It depends on how you count them.
It’s surprisingly hard to tell. You wouldn’t think the total number would be ambiguous, but it’s difficult to know what to include and exclude, and anatomists don’t always agree. Some muscle tissue really can’t be separated into countable muscles. And, believe it or not, the science of anatomy is still advancing: variations in muscle anatomy are discovered almost routinely.
There are only about 200 muscles that anyone, even a massage therapist, might actually be interested in knowing about. When most people ask how many muscles are in the human body, they mean honest-to-goodness bone-movers — muscles that do real work, muscles like pecs, delts, lats, traps, glutes, biceps and triceps, hams and quads, and let’s not forget the cloits and dloits!1Pecs, delts, lats, traps, glutes, biceps and triceps, hams and quads, and let’s not forget the cloits and dloits!
There are maybe another hundred muscles if you include the fiddly little muscles of the hands and feet, and the major face muscles. In school, I had to learn the latin for all them!
All right, all right — if you really must know, there are just shy of 700 named skeletal muscles.2
But that’s including about 400 muscles that, mostly, no one cares about except specialists. I am aware of a few that have clinical importance in my own work, but I’m mostly just barely aware of their existence — like the smaller facial muscles, like the mess of little muscles around and under the tongue and in the voice box, like the muscles around the eyeball, or the web of muscles on the pelvic floor.
But believe it or not, although that’s all of the muscles you can count, that’s still not all of the muscle, not even close.
Muscles comes in three types: skeletal (which moves us), cardiac (obvious), and smooth (not obvious).
If you include smooth muscle — the muscle of the organs — it becomes impossible to count. Smooth muscle blends with other smooth muscle, and exists at every scale from microscopic to large. You have single cells of smooth muscle wrapped around capillaries, and you have organs like your stomach that are wrapped completely in three thick layers of smooth muscle. It’s impossible to say where one smooth muscle stops and the next begins. Perhaps that’s why they call it smooth!3
The little muscles that move our hairs, the arrector pilli, are a sub-type of smooth muscle. They aren’t exactly like all the other smooth muscle, and yet they aren’t exactly like your traps and pecs either. There’s several million of those, but, fortunately, they all have the same name.
And then of course there’s the cardiac muscle: a category of one. Unless you’re a Klingon, you have only one cardiac muscle, but hopefully it’s a big one.
Well, this is how I calculate it. We have …
So I’m going to go with a grand total of approximately 50,100,000,701 muscles, accurate to within 99%.