literature

Anatomy for TF Writers

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Literature Text

AKA "Why knees should never 'reverse direction' in TFs. Ever."

Introduction

So. How many times have you read this exact sentence, or some variation of it, in a TF: "Bobby winced in pain, sickened by the loud 'crunch' of his bones as his knees turned backwards, and he fell to all fours, no longer able to stand"?

I'm guessing the answer is, as it is for me, 'too many to count'. Oftentimes, you find it in inexperienced works, but it's not the sole province of the amateur. You can also find it even in commercial transformation stories - KA Applegate, author of the Animorphs series, which got me and likely a lot of other people into TF, tries to work it in at least once a book, and it bugs me every time.

The main problem, and the reason it's so prolific, is that it makes sense. If you take a dog, or a cat, or a horse, or a bird, and you look at their hind legs, the first thing you'll probably notice is that they bend in the opposite direction of a human's. When a dog or bird lifts its leg, it lifts forward, rather than backwards like when we humans do so, and the natural assumption, and description, of the animal, is that it has knees that go the wrong direction.

"So, then, Miri - why is this wrong?" you ask.

Well, it's wrong because humans and animals have different types of legs.

There's another term you'll hear floating around fairly often. That term being "digitigrade."

Digitigrade vs. Plantigrade (and what that actually means)

Again, this is something I find in a lot of poorly-written, or at least amateur TFs - "Bobby fell over as his legs went digitigrade." To me, it seems to be thrown around very casually a lot - "see, I did my research, I know dogs don't actually have backwards knees, here's a vocab word to prove I'm a good writer!" - and very few people demonstrate that they know what the term actually means. (General writing tip here - using fancy words is just that, using fancy words. This goes for all forms of that. If you drop three or four five-syllable words, it counts for absolutely zero if they're used incorrectly or don't stand up. If they're clearly out-of-place with the rest of the story's vocabulary, they can actually sound less smart than valley girl lingo)

Anyway, I digress.

In order to understand the term 'digitigrade', you have to understand the simple fact that all animals, humans included, with four limbs have essentially the same limb anatomy.

This means that a human's arms and a dog's forelegs are essentially the same as a bird's wings and each other, and the same goes for human legs and dogs' hind legs. This sounds like it contradicts my earlier statement that we have different kinds of legs, but please bear with me a moment.

If you look at your leg, what you will notice are three joints (hips, knees, and ankles)which, on you, are arrayed essentially in a straight line and connected by two bones, your calf and your femur, and ending in your feet. For the sake of this analysis, we're going to add a fourth joint - the joint between your foot and your toes - and ignore your toe joints. Like so:


(please ignore the derpiness of these - my scanner is not hooked up ATM so I had to draw these in paint. With the mouse.)

All four-limbed creatures have these same four joints and four pieces - upper leg, lower leg, foot, and toes, connected to the rest of the body and each other by the hip, knee, ankle, and toe joints.

Now, go look at a picture of a dog's leg. See how round it's 'hip' is, and how it's separate from the rest of it's body? That's because what you're looking at (the 'haunch', in technical terms) is actually the dog's knee; the 'hip' is kind of hidden up at the top of the haunch where the dog's leg attaches to the body. Thus, what you see as the dog's 'knee', the backwards-facing joint, is.....

.....the dog's ankle.

What we see as the dog's 'foot' is actually its toes only, or, as they are known scientifically, it's 'digits'. Thus the term 'digitigrade' - the dog literally walks on its toes. The same is true for all creatures with the backwards knee - cats, squirrels, dinosaurs, etc., all are digitigrade. The only exceptions are hooved animals, but I'll get there eventually.

This does, by the way, include birds, who are essentially the same, but who have a weird toe pointing off the back of their foot to create the talon. I found a picture on the internet a while back showing what a human foot would look like if it were in the same shape as a bird's foot, but let's just say it scarred me for life and you should by no means ever look that up.

Anyway, for the curious, here's a diagram of an avian leg.



Note how, in terms of anatomy and the positioning of the lines (aside from my derpy Paint art) it's essentially the same as the dog's. That's because birds are also digitigrade animals.

The opposite of digitigrade is called 'plantigrade' - that's what we are. That means we walk with our whole foot on the ground. Note that like birds, our feet actually stick a little bit out past our ankle - that's because we need to balance on two legs (we're 'bipeds', to add more vocab words) and the way our feet are designed help absorb the shock of walking that way. Other plantigrade animals include hedgehogs, our close relatives the primates, and rats. (Fun fact - rabbits are plantigrade when at rest, but when they run, they run on their toes.

But back to the point. Now that the anatomy lesson is done, we can move on to....

How This Relates to TF

Yes, Miri is finally getting to the point. (Warning: more derpy paint diagrams)

So, then, I'm hoping you're beginning to see why reversing someone's knee during a TF would be a bad idea(tm). Simply put, it gets rid of one of the essential joints in an animal's leg. It has no reason to happen and actually mucks things up in ridiculous ways.

For example, look at the human foot from earlier:



Now, let's see what happens when we bend the knee backwards...



First of all, my apologies for the potential scarring of your mind. Second of all, this is a backwards knee. (Awkwardly, this is very similar to the anatomy of an arm, but again, digression - that's for next tut) Anyway, let's compare this side-by-side to the dog foot, shall we?



Okay, so, what we now have are four joints (plus some extra toe joints not shown) in both pictures, but look at the configuration - couldn't be more different. In order for this leg to turn into a dog leg, it would need to add a second 'knee' joint, and absorb the toe joint into the ankle joint. As it is, the human can now not only not stand, but also never walk again until the aforementioned problems are corrected. Joints evolved in this particular way for a reason; it is the most efficient way to absorb weight and still achieve a range of motion to allow walking.

However, as I mentioned, this configuration (on the left) lookse very similar to a front limb or an arm - if you put the two drawings side-by-side and added a body, it would still look wierd as fuck, but it would look kind of like a finished creature.

But again, arms are for next tut.

Now, you may be wondering - "I noticed you didn't mention horses. Aren't horses also digitigrade, Miri? Their knees are backwards."

Bonus Section: Unguligrades

And the answer is.... NO! Which is also why it is incorrect to say that a person's legs went 'digitigrade' in a horse TF just as much as it is incorrect to say their knee reversed direction.

Horses are unguligrades, which means that they walk on tiptoe all the time. Essentially, a hoofed animal's hooves are fingernails; this is more noticeable in animals like deer or antelope, with cloven hooves, or semi-unguligrade animals like pigs, capybaras, and elephants, who are not fully elevated onto their toes and are semi-digitigrade. Here's a diagram, for the curious:


Ignoring the fact that I can't draw horse legs when I'm well-rested and using a pencil, let alone at 6AM with no sleep when using the mouse, this is a horse's foot. You'll notice that there's a fifth joint shown - this is, in fact, the same joint as the first joint in your toes or fingers, just strengthened into what is, for horses, essentially a second ankle. It's part of what makes them such strong runners.

So remember these anatomy tips the next time you draw or write a TF! And I don't want to see you ever saying someone's knees reversed again. Got it? :D
Alright, guys. Time for a quick TF anatomy lesson, because it's 5AM and this is clearly a good idea, and also because it has been bothering me.
© 2014 - 2024 faer-windstormfan
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Hey, that's a really great explanation. It helps me extremely with my understanding of anatomy. Unfortunately the pictures are gone. Do you happen to still have them and could you post them separately?