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Research Day: Butt Muscles, Tractor Beams, And STUFF IN ALL-CAPS

Is your ass one muscle or two? A female coworker of mine recently signed up for a course in bellydancing. Here's the conversation we had after her first class:

Me: Is it fun?

Her: No, I hate it. It's way too hard. You have to, like, move the left side off your butt up and the right side down at the same time. I don't even think that's possible, since your butt is just one muscle.

M: Is it? I always kind of though it was two.

H: It's called the "gluteus maximus," so I think it's just one.

M: Well, even so, it can't be impossible to do that. I mean, your tongue is a single muscle, and you can move different parts of it in different direction.

H: No you can't.

M: Sure you can. If you stick out your tongue you can move the tip of it up and down without moving the back of it.

H: Oh, I see what you're saying. Like, the front of your tongue is the right side of my butt and the back part of your tongue is the left side of my butt?


M: I'm sorry, but as a married man I can no longer participate in this conversation.

I spent a ridiculous amount of time searching the Internet for an answer to this question. My operating assumption was that the human body only contains one gluteus maximus muscle, but I kept coming across illustrations such as the one found here which make it look like there is one gluteus maximus per leg.

Finally I dusted off my old MeFi account and Asked Metafilter. A few minutes after I posted ther query, ikkyu2 weighed in with this: "Two. Definitely, incontrovertibly two, innervated each by the inferior gluteal nerve (right and left)" and cited this page as evidence. Based on the fact that his Mefi profile page lists his occupation as "neurologist," and that he knows how to use words like "innervated," I'm going to believe him.

Update: Although I didn't mention bellydancing in my Ask Metafilter post, that must be the vocation where butt muscle inventory most frequently occurs because equipoise chimed in with this: "I'm guessing [that a previous responder who said that you can't move each side of your butt independently] is not a bellydancer. In Middle Eastern dance,, you can shake your hips by squeezing the right glute, then the left, then the right, etc. ... From experience, you definitely have a separate muscle in each buttock."

What's the origin of the phrase "tractor beam"? "We're caught in a tractor beam! It's pulling us in!" So says Han Solo in Star Wars: A New Hope. This may not be the first time I heard the phrase "tractor beam," but it's certainly the first I remember. But how one earth did a piece of farm equipment come to be associated with staple of science-fiction?

Surprisingly, there's a website devoted to questions just like this one. Science Fiction Citations describes its mission as "hunting for the earliest citations of sf words," and "tractor beam" is one of its many entries. It traces the phrase back to the 1931 story by E. E. Smith entitled "Spacehounds of IPC," which includes the line "Brandon swung mighty tractor beams upon the severed halves of the Jovian vessel, then extended a couple of smaller rays to meet the two little figures ..."

I found a few other pages that corroborated this, but all just attributed it the phrase to Smith without speculating as to why he chose the word "tractor." But in this discussion thread (Google cache), someone posits a fairly plausible hypothesis: that "tractor" is just short for "attractor." And someone else points out that there is no need to look beyond the dictionary for an explanation: the word "tractor" has, as one of its definitions, "something that pulls or draws."

Bonus fact: accorording to this essay, E. E. Smith also gave us the words "forcefield," "mothership," and "hyperspace."

Why, in legal contracts, are some line written in all capitals? I recently had to sign a lengthy indemnity waiver for an event I will soon be participating in, and while most of it was written using the standard rules of capitalization, there were many passages which were written in all-caps. That got me to wondering if the passages in all capitals shared some property, and were capitalized out of legal necessity or tradition.

I asked local blogger and legal mind Snarky, and here's what he wrote:

Items in contracts that are in BOLD AND ALL CAPITALS are usually those areas in which (1) they are asking for an explicit waiver of an important right (and thus can claim that a reasonable person would not have overlooked the item); (2) are contractual terms that vary greatly from what a common law presumption of the terms would be, were that item not present; or (3) for mere decoration (such as "BUYER" and "SELLER" in a buy/sell contract).
Doing a little legwork on my own, I found what probably explains the presence of all-cap statements in contracts. The General Definitions section, and one thing you can do to automatically render a portion of text "conspicuous" is to put it "in capitals equal to or greater in size than the surrounding text."

Posted on July 21, 2005 to Research Day


This is not quite the same, but it always irritates me that, in memos or other company documents, our corporate lawyers insist on capitalising the initial letter of words that are really just common nouns; eg

"...and so the Company will be embarking on this Project in order to maximise the return for Investors before our Financial Results later in the Year."

Posted by: JohnW on July 25, 2005 1:48 AM

The tongue is not formed by a single muscle. This, I realize, was not the main point of your post, but I feel that it is my professional responsibility to bore the crap out of anyone who even mentions oral anatomy.

Posted by: looking_down on July 25, 2005 4:56 AM

The Gluteals are actually made up of three muscles. The gluetus maximus is the large, superficial muscle that is the most posterior of the group. The gluteus medius is located on the outside of the hip and is mostly superficial, except for the posterior portion which is deep to the maximus. The gluteus minimus is deep to the gluteus medius and is inaccessible, though the dense fibers can be felt beneath the medius. The gluteus minimus performs the opposite movements as the other gluteals. The minimus flexes and medially rotates the hip, while the other gluteals extends and laterally rotates the hip.

As a Licensed Massage Therapist, I find this area to be one of the main areas I work on when a client has lower back pain.

Posted by: Joshua on July 25, 2005 7:28 AM

Unfortunately I can't point you to a source, but I know I've read a study that claimed material written in all capitals is more difficult for humans to comprehend than mixed-case.

So the way I see it, it serves a dual purpose for the legal folk: 1) they can claim a reasonable person will not overlook it, 2) they can rest assured that the casual reader will ignore it as soon as they do notice, as it is more difficult to read than the surrounding text. Win-win!

Posted by: Drew on July 25, 2005 8:52 AM

The whole "conspicuous language" thing is the legal justification for all-caps parts of contracts, but I am a lawyer, and I can tell you that the real reason (and I may be hunted down by legal community ninjas for revealing this) is that lawyers like to SHOUT ALL THE TIME.

Posted by: Dan Someone on July 25, 2005 11:33 AM

I love the way you think up crazy questions and then go to all this trouble to find out the answer...I tend to either take things as they are or wonder about them for the rest of my life...

Posted by: miel on July 25, 2005 1:36 PM

Don't they often redefine or narrowly define words in contracts? For example, "the USER, herby any party that visit our website or links to us or even thinks about our website, will agree to give us one dollar whenever we ask". I was under the impression that oddly cased words were those that had meanings specifically and narrowly defined either in law or in the language of the contract.

Posted by: Chris on July 25, 2005 5:24 PM

Seeing as one can clench each cheek independently, it's gotta be two muscles. Try it.

Posted by: KellyO on July 25, 2005 8:01 PM

I used the term "tractor beam" on my blog about a week ago. It had looked so weird that I had to type it into google, myself, to make sure that it wasn't a phrase that I had some how bungled in my own brain. Glad to hear that I wasn't the only person with that particular obsession last week.

Posted by: maybeknott on July 25, 2005 8:56 PM

To Chris: Yes, capitalised terms (either the first letter or the whole word) are often used in contracts to ensure that a certain definition of a term used throughout the contract is applied in the interpretation of the contract. These terms are linked to a definition section, often found at the front or back of a legal document, or at the very least to a definition found elsewhere in the document. If the terms are capitalised but not linked to a definition, your lawyers are probably trying to screw you by making you think that they have done more work than they have to bring your document up to scratch, which can then be used to justify an excessive bill.

To JohnW: If you look at legal documents often enough to be irritated by the practice, then the (really quite valid) reason for it should be patently obvious.

As for all bold and all caps: There are certain contractual terms which are legally required to be printed in such a way so that the reader's attention is drawn to that term. The most familiar example of this is limitation or exclusion of liability clauses. This only seems to be a legal requirement in the US. In NZ we just presume you have the common sense to read the whole contract, and if you don't too bad, although where people don't normally deal with contracts there is a common law rule that you must draw their attention to particularly onerous contractual provisions or you will be unable to rely on those provisions.

Yawn. Sucks to be a boring lawyer.

Posted by: H.A. on July 25, 2005 9:03 PM

Not apropos of anything, but for some reason i always mix you up with mathowie - I have to conciously remember that you're not the guy who made metafilter.
I have no idea why.

Posted by: muddylemon on July 25, 2005 9:32 PM

As a used to be Trekkie, the term "tractor beam" is far fropm foreign to me.. and it does pose a certain amount of sense.

On a farm, you have a tractor. That tractor does an incredible amount of pulling- be it pulling a drag to smooth the road, pulling a disc to turn soil, or pulling the drunken idiots' car out of the ditch where they got it stuck the night before. The tractor beam of science fiction fame does the same- it grabs hold, digs its heels in, and pulls.

The bellydancing/gluteous bit- sorry, that's just funny. I loved the dialogue as well.

Posted by: Debra on July 25, 2005 10:57 PM

I guess now that your estate has been planned, you're free to waive your rights more often?

Posted by: Ernie on July 26, 2005 4:18 AM

Greetings from Guelph! I must chime in the Veterinarian perspective of the muscle discussion.

1. About Ass: Joshua is correct, the Glutes are 3 muscle groups (on each cheek). In humans, the Gluteus Maximus is the largest, but in dogs and cats (and all quadrupeds I know of), The Gluteus Medius is the largest, the Gluteus Maximus is smallest (and absent in ruminants) and the Gluetus Minimus is intermediate in size.

2. About Tongue: The tongue is comprised of many muscles, which can be divided into two groups: The intrinsic muscles run in all three directions (front to back, side to side and up and down) and are the main muscles used in flicking, rolling, and all the other wonderful things our tongue does. The extrinsic muscles are the ones way at the back of the tongue which anchor the tongue to the skeleton (yup, the tongue bone attaches to the chest bone).

Sorry to bore all of you with the science of ass and tongue. I blame it on my distance from Seattle and more specifically, The Elysian Brewery.

Posted by: Matthew on July 26, 2005 3:15 PM

Yes looking down! The tongue has many muscles!

Actually just learned this several months ago and was totally unsettled by the pictures of all the muscles coursing up from the floor of the mouth into the tongue and disappearing under the creepy bumpy tongue-cover...

Apologies for the digression, but surely this is a matter of interest to many!

Posted by: lily on July 26, 2005 3:30 PM

Matt hinted at the explanation already, but since it came up in the comments again, I feel compelled to the origins of the tractor word in a little more detail.

The Latin word trahere which means 'to pull' (traho = I pull, traxi = I pulled, tractum = [I have] pulled) is the original source of that word. Words in modern languages that are taken from Latin are usually derived from the third form I put in the brackets there. I don't know the english name of that form, probably something like 'past participle'.

Attractor is not just a long form of tractor, it's the word tractor with the preposition ad in front of it, where the d changed to a t. Ad means 'to' or 'towards'. While a tractor does just general pulling, an attractor pulls something towards a certain position.

For example, an attractive person pulls us towards themselves.

A contract (con = together) pulls two parties together (* I'm going a bit on a limb here, because contrahere is probably a well-established verb in its own right, yet this is supposedly the origin.).

A distraction (dis = apart) pulls groups of people apart (see * as well).

I didn't even like Latin...

Posted by: Thomas on July 29, 2005 2:37 AM

Of course there are two, you've heard of a thing called the butt crack which cracks the muscles in half, right? It still makes a good story though, so, forgiven.

Posted by: James on August 1, 2005 12:49 AM