Only One Animal with 4 Knees?

[Jinx]

I heard a trivia question which said that elephants are the only animals with 4 knees. But, what about horses, cows, and dogs - as examples? Or, am I to WAG that they are technically maybe 2 or 4 elbow joints, and not technically 4 knee joints? - Jinx

[MC_Master_of_Ceremonies]

In this case knees means joints that are hinged at the front.

[astro]

Ohhh… animal trivia

A crocodile can’t stick out its tongue.

An elephant can be pregnant for up to two years.

Giraffes have no vocal cords.

Elephants have been found swimming miles from shore in the Indian Ocean. Apparently, even they like to spend time at the beach.
The trunk of an elephant is operated by 40,000 muscles.

A lion’s roar can be heard up to five miles away.

All elephants walk on tip-toe, because the back portion of their foot is made up of all fat and no bone.

The heart of a giraffe weighs 25 pounds, is two feet long, and has walls 3 inches thick.

The African elephant’s ears weigh more than 100 pounds each.

Erect giraffe penises are four feet long.

Elephants have been known to remain standing after they die.

Elephants are the only animal that can’t jump.

The muzzle of a lion is like a fingerprint - no two lions have the same pattern of whiskers.

The elephant is the only animal with four knees.

Elephants, giraffes and man all have seven vertebra in their necks.

[Darwin_s_Finch]

Elephants do not have four knees. No animal does.

The front “knee” of an elephant is actually its wrist. All terrestrial mammals are built upon the same basic body plan. Here is a reasonably good pic of an elephant’s skeleton (with the elephant still around it!).

Note the structure of the forelimb. The big knobby bone halfway down is the elbow, and it bends, not surprisingly, just like ours does. Below is the thick wrist. This is the part that, when bent, may give the impression of being a knee. Which, of course, it isn’t.

Note also the hind limb. You can’t see the hind foot too well in the image, but you can see the true knee: the joint at the end of the vertical bone (the femur).

Horses, etc., are built similarly, but with different bone length proportions and more “bend” to many of the joints (the elephant is built more pillar-like to better support its weight). Here is a good pic of a horse skeleton. Again, note the true knees on the hind limb and the knobby elbow of the forelimb (up near the ribcage - the lower joint is its wrist again, and the lowermost joints are “finger” joints). Also note the big ankle bones (or “calcaneus”) on the hindlimb (you can move your cursor over the various bones and see what they are).

[GuanoLad]

People like to say that animals have “backwards bending” knees when referring to the hind legs, but this is not true. Those are its ankles, and they bend the same ways as ours do. All their joints do. It’s the muscles that are different sizes and placements that reinforce the illusion.

[Darwin_s_Finch]

*Originally posted by GuanoLad *
People like to say that animals have “backwards bending” knees when referring to the hind legs[…]

This is especially true of birds (that is, many people think birds have backward-bending knees). Here is a rather freaky-looking picture of a bird skeleton, but one which illustrates the point fairly well. You can see the real knees up by the ribcage. In life, the bird’s knees are held close to the body and are often obscured by the wings when on the ground, so they aren’t often seen. As GuanoLad points out, the “backwards knees” are actually the ankles.