No, It's Not Actually Called The Knee-Pit

You know what I'm talking about when I say the word 'knee-pit', right?  The knee equivalent to your shoulder's armpit.  The back of the knee.  You know, the knee-pit.

One of the many 'facts' that show up on the internet is that the back of the knee doesn't have a proper name.  We're supposed to believe that the people who came up with a name for the artery that runs along the inside of your thumb wouldn't come up with a name for your knee-pit (the artery is the called the princeps pollicis artery, FYI)?  Well, like so many facts on the internet, it's not true.  There is, in fact, a proper name for the knee-pit.

The proper name is the popliteal fossa.  A fossa is a pit, cavity or depression (usually used in reference to bones), while popliteal is a reference to the popliteus muscle, which is in the back of the knee.  The popliteal fossa is the entire knee-pit area.

Other proper -pit names are:
The axilla (or oxter is you're from the UK) is the proper name for the armpit.
The cubital fossa is the proper name for your elbow-pit.
The proper name for the anatomical snuff box is the radial fossa.

What's the anatomical snuff box you ask?  It's the depression that's bordered by the... ummm... that tendon that's on your hand that goes to your thumb... here, I'll just show you a picture.  The label for the anatomical snuff box is legible on my monitor, but if it's not for you, click to enlarge the image.  It's named after the habit of snuff (powdered tobacco) users placing their snuff in that depression and then snorting it from there.

Click to embiggen, clicky-poppy.

And now you know how to refer to your knee-pit properly (I know it comes up in conversation a great deal): The popliteal fossa.  Now you just need to figure out how to pronounce it properly.

---

Sources:
Anatomical snuff box image taken from ChestOfBooks.com's Applied Anatomy: The Construction Of The Human Body
Dictionary.com's entries for popliteal, fossa, popliteus, axilla and oxter.
TheFreeDictionary.com's medical dictionary entry on fossa
Wikipedia.org articles on the popliteal fossa, the axilla, the cubital fossa, the anatomical snuff box and the princeps pollicis artery