Etymology of ひざまずく


I can't resist trying to find patterns in words. These three words, for
example, seem to fit a similar pattern:

  * 頷{うなづ}く = [項]{うな} + 突{つ}く (source: [community wiki](https://japanese.stackexchange.com/questions/6581/kanji-for-native-japanese-concepts-kunyomi-spanning-multiple-morphemes/6632))
  * 躓{つまづ}く = [爪]{つま} + 突{つ}く (source: [community wiki](https://japanese.stackexchange.com/questions/6581/kanji-for-native-japanese-concepts-kunyomi-spanning-multiple-morphemes/6632))
  * 額{ぬか}づく = [額]{ぬか} + 突{つ}く (source: [gogen-allguide](http://gogen-allguide.com/nu/nukazuku.html))

However, I can't seem to find the etymology of 跪{ひざまづ}く anywhere. Since it
_appears_ to fit the pattern, I'd like to guess:

  * 跪{ひざまづ}く = [膝]{ひざ} + ま + 突{つ}く

But where does the ま come from? It doesn't seem to fit the pattern neatly like
the others.




It would be nice to have some more authoritative sources on this topic (if
there are any), but I'm not convinced there is. A lot of the pages I could
find said they don't know where it comes from, and I'm not sure anybody really
does...

* * *

But one theory _may_ be, in the [Wikipedia article for
膝{ひざ}](http://ja.wikipedia.org/wiki/%E8%86%9D), it says:

> ...つま先と膝をついて座る座り方は「跪く」と言い...

A rough translation of that might be:

> "...the way of sitting that is falling on your knees and toes and sitting
> down is called '跪く'..."

So I think it may be a combination of 膝{ひざ}, 爪{つま} and 突{つ}く.

* * *

I'm a bit sceptical of the "best answer" at this link (other pages say "つ" in
"つまづく" comes from "爪" rather than "蹴" for example), but this seems to be more-
or-less what one of the non-accepted answers at [this Chiebukuro
question](http://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1345302328)
says, saying that "〜まずく" is "つまづく" and that "つまづく" comes from "爪{つま}" and
"つく".




It would be nice to have some more authoritative sources on this topic (if
there are any), but I'm not convinced there is. A lot of the pages I could
find said they don't know where it comes from, and I'm not sure anybody really
does...

* * *

But one theory _may_ be, in the [Wikipedia article for
膝{ひざ}](http://ja.wikipedia.org/wiki/%E8%86%9D), it says:

> ...つま先と膝をついて座る座り方は「跪く」と言い...

A rough translation of that might be:

> "...the way of sitting that is falling on your knees and toes and sitting
> down is called '跪く'..."

So I think it may be a combination of 膝{ひざ}, 爪{つま} and 突{つ}く.

* * *

I'm a bit sceptical of the "best answer" at this link (other pages say "つ" in
"つまづく" comes from "爪" rather than "蹴" for example), but this seems to be more-
or-less what one of the non-accepted answers at [this Chiebukuro
question](http://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1345302328)
says, saying that "〜まずく" is "つまづく" and that "つまづく" comes from "爪{つま}" and
"つく".

