How Many Muscles?
A (slightly tongue-in-cheek) tally of the body’s many muscles
Articles in the Biological Literacy series are fun explorations of how the human body works. See below for a complete listing of articles in the series.
There are about 300 skeletal muscles in the human body. Sort of. It depends on how you count them.
How many really?
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!1
Pecs, 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!
No, really, how many are there?
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.
The grand total
Well, this is how I calculate it. We have …
- 200 muscles that might get discussed in a gym
- 100 more muscles that are pretty obscure, but any self-respecting massage therapist still knows about them
- 400 more muscles that are really danged obscure, but various specialists know about them, and a handful of them are of special interest
- several million hair-raising muscles
- several billion smooth muscles cells blended together
- exactly 1 heart muscle
So I’m going to go with a grand total of approximately 50,100,000,701 muscles, accurate to within 99%.
The Biological Literacy Series
- 7 Reasons Older Adults Don’t Stay in Exercise Classes — And 7 Reasons Why they Should
- An Introduction to Biological Literacy — Why you need to know more about your body
- An Open and Closed Case — An explanation for a strange duality of muscle sensation observed in massage therapy
- Dance of the Sarcomeres — A mental picture of muscle knot physiology explains four familiar features of muscle pain
- Eccentric Contraction — A peculiar bit of muscle physiology
- From Atoms to Elvis — A wide-angle look at the foundations of biology
- Getting On Your Nerves — Can you damage your nerves when self-massaging?
- How Many Muscles? — A (slightly tongue-in-cheek) tally of the body’s many muscles
- It’s the homeostasis, stupid — Vindication for an unconventional view of knee pain, and probably a lot of other common aches and pains
- Natural Imperfection — Evolution doesn’t care if you have back pain … just as long as you can breed
- Oh, a flow-induced system of mechanotransduction! Of course! — A century-old mystery of bone biology was solved just a little while ago
- The Respiration Connection — How dysfunctional breathing might be a root cause of a variety of common upper body pain problems and injuries
- Singing, Breath and Scalenes — Connections between singing, breathing and a strange group of muscles
- The Sixth Sense — Proprioception, the vital but mysterious sensation of position and movement
- Spinal Nerve Roots Do Not Hook Up to Organs! — One of the key “selling points” for chiropractic care is the anatomically impossible premise that your spinal nerve roots are important to your general health
- Stiffness, tightness and limited range of motion are not always the same thing — An interesting little thing to understand about your body
- Ten Trillion Cells Walked Into a Bar — A humourous and unusual perspective on how, exactly, a person is even able to stand up, let alone walk into a bar
- Ugly Bags of Mostly Water — The chemical composition of human biology
- We Are Full of Critters — The human body is a colony of ten trillion co-operating cells
- When To Worry About Shortness of Breath … and When Not To — Some common, minor & treatable causes of a scary symptom explained
- Why Do We Get Sick? — The connections between poor health and the lives we lead
- Why Does Pain Hurt So Much? — How an evolutionary wrong turn led to a biological glitch that condemned the animal kingdom — you included — to much louder, longer pain
- Why Massage Makes You Tingle — The physiology of sensation in muscle tissue
- You Might Just Be Weird — The clinical significance of normal — and not so normal — anatomical variation
- The ‘Use It Or Lose It’ Principle — The importance of stimulation and movement in healing
- SY Ten Trillion Cells Walked Into a Bar — A humourous and unusual perspective on how, exactly, a person is even able to stand up, let alone walk into a bar
- SY Why Massage Makes You Tingle — The physiology of sensation in muscle tissue
- The most interesting anatomy text I know of is Anatomy of Movement, by Blandine Calais-Germaine. This book is simply the best resource there is for understanding functional musculoskeletal anatomy.