Digitigrade animals don’t have “backward knees”

Today, I'd like to address one of the most common mistakes that new or young artists make when they start drawing animals: "Backward knee" syndrome. This is one simple tip, but if you haven't discovered it yet, it's going to make a world of difference.

"Digitigrade" is an animal that walks on its digits, or toes. digitigrade animals include canines, felines, elephants, birds, dinosaurs and more.

Humans, on the other hand, are "plantigrade" animals, meaning that we walk on the soles of our feet rather than the toes. And therein lies the confusion. Digitigrade animals don't have backward knees. Rather, their feet are elongated: they are balancing on their toes, and what looks like a knee is actually the ankle. Check it out:

Skeletal diagram of a cat

Now compare that to a human foot:

Muscle and skeletal diagram of a human leg


Junsui (unregistered visitor)

Thank you! This has been bothering me for a very long time. I've just avoided drawing animals.

Kim - 网站管理员

So glad to be helpful! I remember my own "aha!" moment when someone first showed me a canine skeleton.

Brandon (unregistered visitor)

The really funny one is an ostrich, the knee is hiding~!

EduxBR (unregistered visitor)

Thank u sooooo much! =D


Mike Rowe made this same mistake on "Dirtiest Jobs" when he visited the Ostrich Farm.

Kim - 网站管理员

I did not know that! That's pretty funny. Thanks for the trivia! :)

Dex (unregistered visitor)

I've always thought this.

Raffety Sean

OMG! Thank you!

Kim - 网站管理员

It's an eye opener, isn't it? :D I remember my aha moment!

Birds, dogs, and cats bend their ‘knees’ backwards because those are actually their ankles! | Net Sauce (unregistered visitor)

[...] (Source) [...]

factPicture | Digitgrade (unregistered visitor)
Fog (unregistered visitor)

This is a great post. I learned with animals though, so my opinion probably doesn't count.

This is the same with birds, a lot of people don't realize, and it's even harder to show since their hip and upper leg is on the inside of their body and it's nearly impossible to see. At least with mammals you will have vague points that resemble human anatomy.


Another thing I want to point out is that some animals are plantigrade (not including the obvious primates) and a lot of people don't know this and once they learn how to draw dogs and cats may incorrectly draw bears and mustelids (weasels). The more you know.

Kim - 网站管理员

That is an excellent point! Maybe this will make a good followup post. :)


What is the joint between the ankle and called?


Never mind. I was looking at the picture wrong.

aAvian (unregistered visitor)

Also, another tip - ungulates (hooved animals) are like other digitigrade animals, with a catch - they walk on their nails, not even their toes! Horses have one toe with one nail that they walk on, pigs and other ungulates have two-four toes and walk on those toenails. That's all a hoof is - a big ol' toenail!

Kim - 网站管理员

That is an awesome contribution! Thank you! :)

Anderson Marques (unregistered visitor)

And a horse?

Bogdan (unregistered visitor)

But Pluto (Disney) have backward knees :)

Sean Kresge (unregistered visitor)



Ha! Ha, ha, ha, ha, I spent 4 years in an accredited university carrying a double major, one of which was biology. You would think this would have been taught in the physiology classes, or at least covering mamology. This is brand new to me and is amazing. Learning is a life long persuit and this just put me forward on the learning scale. That was magnificent.

Kitsune (unregistered visitor)

Thank you. I have been struggling to understand this one for a long time. And I needed to know this most just now!


Great article! I never really thought of that but just drew what saw. I guess it does pay to learn some anatomy! Now I'm going to stare at my dogs legs!


This was a very helpful article. Digitigrade anatomy is very difficult to draw at first as their limbs don't work the same a humans. Thank you. :)

Shari (unregistered visitor)

Here's a good one. When hopping at speed, a kangaroo hops on its toes, but when it's grazing it'll use all 4 limbs, and its entire foot will at times be resting on the ground as it does the slow hop for food. Their tails never touch the ground as they do the fast hop because they need the tail as a rudder, but the tail will almost always be on the ground for the slow 4-limb hop because they need it for balance. At the fast hop, the tail bobs up and down, but it only appears to touch the ground.