Tuesday, February 07, 2006

My favorite muscle

Each day I receive a "Word a Day" e-mail from the Wordsmith. Last week I was delighted to get a message related to my favorite muscle. Here is an excerpt from the e-mail:
sartorial (sar-TOR-ee-uhl) adjective

Related to a tailor or tailored clothes.

[From Late Latin sartor, tailor.]

Today's word has a cousin, sartorius, a long narrow muscle in the leg, the longest muscle in humans. What would tailored clothes have in common with a muscle of the leg? Sartorius is so named since it is concerned with producing the cross-legged position of tailors at work.
If you have the opportunity to dissect a cadaver, you can't miss the sartorius. The longest muscle in the human body, the slender sartorius wraps like a python across the thigh and knee, attached at one end to a large protuberance on the hip bone (the anterior superior iliac spine, or ASIS for short) and to the tibia just below the knee at the other end.

In spite of its impressive appearance, the sartorius hasn't become a household term like the more familiar "quads," "hamstrings," "biceps," and "lats." Perhaps this is because the muscle normally is buried under a layer of fatty connective tissue, and rarely stands out like the massive quadriceps next to it. Here is an extraordinary exception:

See the long skinny muscle just below the contest number on his left hip? That's the sartorius. While other people are admiring Aaron Maddron's biceps or lats, I'm thinking, "Now that's a nice sartorius!"

To be honest, I had no idea that tailors assumed a characteristic position with their legs until I learned about the sartorius. Tailors don't have a monopoly on this position. Anytime you sit cross-legged with your left outer ankle resting on your right knee (or vice versa), you're doing it too.

From an anatomical perspective, describing the actions required to cross your legs is more complicated than you might guess, so bear with me. Imagine yourself standing, face and palms facing forward, feet together, elbows and knees straight. Anatomists call this the "anatomical position." Now (1) bend your left knee; (2) lift your left knee so that your thigh makes a right angle with your trunk; (3) move that knee outward; then (4) rotate the left thigh so that your foot swings towards your right knee. Each of those actions - knee flexion, hip flexion, hip abduction, and hip external rotation - happens when you activate the sartorius on the left side. Now all you have to do is flex your right knee and hip, find a chair to sit on before you lose your balance, make sure your left leg is resting on the right knee, and you've assumed the tailor's position.

So, could you cross your legs without a sartorius? Yes, because every action assigned to the sartorius is also performed by other muscles. And it's relatively weak. Given its small diameter, the sartorius doesn't generate much force compared to its neighbors in the thigh. Perhaps its most important function is protection. In the anatomy lab, pulling the sartorius to one side reveals two major blood vessels on their way to and from the calf - the femoral artery and femoral vein. Covering those vessels with a muscle presumably offers better protection than mere skin, fat, and connective tissue.

Photo of Aaron Maddron from Thigh Masters: Men with Great Legs


At 2/09/2006 11:21 AM, Blogger Julia said...

your interests never cease to amaze me!!!


At 5/06/2006 10:27 PM, Anonymous Anonymous said...

Great description of sartorius. Found your blog while googling about 'tailor's position', now I understand.
med student, Melbourne, Aus

At 5/19/2006 2:34 PM, Blogger Megan Merchant said...

Ballet dancers emphasize use of the sartorius in much of their technique and training. Possibly another good place to find pictures.

At 2/22/2007 7:41 AM, Anonymous Anonymous said...

Re mjdancer. Nureyev's sart. was nearly as well developed as his vastus medialis (partly genetics, partly trainng). Sart. is also well exercised in backcountry skiing during the recovery stroke (pulling the ski forward through the snow). Also high jumpers and hurdlers often show quite remarkable development.

At 5/22/2007 6:59 PM, Anonymous Anonymous said...

i have been getting cramps in this muscle. they are very painful and don't go away with simple streching. what can i do to keep this muscle from cramping

At 5/22/2007 8:56 PM, Blogger Brad said...

Probably depends on the particular cause of the cramping. Many conditions cause muscle cramps - could be simple sports injury or something more serious. A doctor would ask you for a detailed history of the pain - when did you first notice the pain, how long does it last, does anything trigger it or make it feel better, etc. Then he/she would examine you and possibly order lab tests or imaging studies to nail the diagnosis and/or rule out the unlikely worst-case scenarios. So the bottom line is, if the pain persists, I'd recommend scheduling a visit with your physician.

At 10/23/2007 1:48 PM, Anonymous Anonymous said...

I have just suffered an accident which has lost me the use of this muscle. I believe it to be crucial to leg function and I would welcome a chat/your e mail address to give you details so that you can use it to further thinking on the structure and usefulness of your favourite muscle.

Many thanks Greg@lawlings.freeserve.co.uk

At 9/12/2008 7:19 AM, Blogger eri said...

Hey! Thats my favorite muscle too!
in spanish they say:



At 2/08/2011 8:58 AM, Blogger Unknown said...

I am finding your blogs to be educational and a great read. I am just getting started. Thanks for sharing luv.

At 3/18/2011 1:45 AM, Anonymous dozorr said...

'Perhaps its most important function is protection. In the anatomy lab, pulling the sartorius to one side reveals two major blood vessels on their way to and from the calf '

I don't think you can resonably defend that comment from an evolutionary perspective.

At 3/26/2011 8:45 PM, Blogger Brad said...

Dozorr, I agree. It was pure speculation.

At 3/31/2011 1:38 PM, Anonymous viagra online pharmacy said...

According with the dictionary the proper Latin plural form of the adjective quadriceps would be quadricipites and this is my favorite muscle. 23jj

At 6/05/2011 9:13 AM, Anonymous Anonymous said...

Hi, i've just undergone surgery and instead of cutting the gracillis the surgeon actually cut the satorius, they have admitted their error. i am in real pain from my hip to my knee, would you think this is coming from the sartorious?

At 6/08/2011 10:04 AM, Blogger Brad said...

Anonymous on 6/5, I don't know for sure, but yes, I think your pain could be related to the severed sartorius.

At 6/12/2011 7:21 AM, Anonymous Anonymous said...

I have had a cramp in both satoris muscles frequently. They started over ten years ago, I just associated them with a pinched nerve in my back. They happen at night. Usually if I've stood on my feet a lot that day. I had disc surgery and I still get them. Lately I have developed motorneuron problems. Now I don't know whats more fun, satoris cramps or satoris cramp with calf cramp. Owwww!!!!

At 7/25/2011 8:10 PM, Anonymous Anonymous said...

i'm a physical therapist...and i just realized i've been paying too much attention on the common muscle groups :D. you may wanna talk about the small deep muscles of the buttock next time.i'm learning from your blog..it refreshes my memory on anaphysio and some kines :D.

At 11/02/2011 11:05 PM, Anonymous Anonymous said...

I am 2nd year osteopathic med student and I was in a candid discussion about random anatomy with one or our lab techs.
A speculation we had for the sartorius and gracilis and semitendinosus was for knee proprioception. All three insert at the pes anserinus, but originate at different places which makes for good triangulation. None are particularly powerful and they are innervated by different nerves. Propriocetion of the knee joint must be hugely important for us to walk about on flat ground or not so flat terrain.
Just ideas.

At 12/15/2011 1:32 AM, Anonymous Anonymous said...

Having severe burning cramps ,feels like my mucles (sartorius) inner thigh are going to rip free from bone allways in same aeria sometimes last up to 45 min , potassium supplements work somewhat. Why do they last
So long . E mail beyondballroom@yahoo.com if you have
Any suggestions

At 12/26/2011 8:35 AM, Anonymous Anonymous said...

I suffer from the same excruciating cramps usually at night, after a long period of sound sleep. I move my leg and am instantly in spasm! It can take a quite awhile to get relief, usually by walking it out and using a thumper type massager along the whole muscle line. I have asked drs and PT's about it and I usually get a shrug and a blank look. If only they had experienced it, I'm sure they would have found an answer to preventing it by now. Any suggestions are very welcome!

At 12/28/2011 10:15 AM, Anonymous Anonymous said...

I am a physical therapist and triathlete. I have personally felt the wrath of a cranky spasmed sartorius. I have witnessed other triathletes experience sartorius spasm in the bike to run transition area. Very painful. Feels like blood vessels are being pulled on (from my anatomy classes I see that it is anatomically near major vessels). Here's what happens: ride bike for a few hours and toast all the big muscles in your legs. Smaller, weaker muscles have to kick in. They get really toasted. Now sit down and put the sartorius in a shortened position which just happens to be that of sitting down in the bike to run transition area to put your running shoes on. Wham! If you don't know how to gently elongate the muscle (read stretch here) to relieve the spasm you just seize up in agony for a few minutes. Try to avoid the shortened position of any cranky muscle in a triathlon or just laying in bed with tired legs after a long day. I know we would all rather take a pill for what hurts us but we really need to take time to learn how to stetch out all of our stiff, tired, tensed, and toasted muscles. It has been my observation as a PT for 33 years that half the people don't know how to stetch and the other half just cant' find the time.

At 2/18/2013 8:55 PM, Anonymous Anonymous said...

Hello there -fellow blogger and ballet dancer and would love to write an article and consult you on it. Particularly with this sartorius muscle etc. In case you didn't know, Ballet dancers are like amatuer anatomists... so this is how I found you -- by researching a topic for my work. What is your email? My blog is www.madamebnyc.blogspot.com the best email to use for me is imaniteague@hotmail.com



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