Problem parsing this sentence, particle (postposition) の


> (中尉は）両手で刃｛やいば｝を腹｛はら｝の奥深く押さえつけながら、引き廻して行かねばならぬのを知った。

My trouble lies with

> 刃を腹の奥深く押さえつける

If I consider 奥深く to act as adverbial form of 奥深い, then I don't know what is
modified by 腹の: taking の 助詞 to work in attributive role modifies nouns, and
there is no noun here; taking の to work as an agent case marker doesn't make
sense to me, as there is nothing for 腹 to act upon.

Taking 奥 as a noun doesn't make sense either because it's missing a case
marker, something like

> 刃を腹の奥 **に** 深く押さえつける （with に in allative role)

**In other words, how does の work here?**

A bit more if necessary for context:

中尉は右手でそのまま引き廻そうとしたが、刃先は腹｛はらわた｝にからまり、ともすると刀は柔らかい弾力で押し出されて来て、両手で刃を腹の奥深く押さえつけながら、引き廻して行かねばならぬのを知った。




That 奥深く is not an adverb おくぶかく but two nouns of おく and ふかく.

The の functions as the possessive marker for the 腹, in other words 腹の奥 stands
for deep inside the abdomen. The 深く here is a noun (like 遠く・近く・多く）that means a
deep part and the relation between 腹の奥 is 'equivalent'（同格）.

In this example, those nouns are used like an adverb by their own, but if you
add に, it should be 腹の奥深くに.




That 奥深く is not an adverb おくぶかく but two nouns of おく and ふかく.

The の functions as the possessive marker for the 腹, in other words 腹の奥 stands
for deep inside the abdomen. The 深く here is a noun (like 遠く・近く・多く）that means a
deep part and the relation between 腹の奥 is 'equivalent'（同格）.

In this example, those nouns are used like an adverb by their own, but if you
add に, it should be 腹の奥深くに.

