The accusative is a worm
It slithers its way into every corner of the language. I found a use of it today that I’ve not seen previously, whilst browsing through PMEG.
It sort of indicates position of a part, though usually a body part. Here’s one of the PMEG examples:
li haltis dum momento, la kapon klinita iom flanken.
he stopped for a moment, his head inclined a little to the side.
Notice how the sentence is quite short and sharp in English too. One way of understanding it, is to imagine it a little fuller with e.g. tenante:
li haltis dum momento, tenante la kapon klinita iom flanken.
he stopped for a moment, holding his head inclined a little to the side.
This also shows why the “n” might be suitable here, it’s because you’re implying a tenante, havante or metinte (holding, having, or having put), of which the kapo is the direct object.
A sneaky, slimy worm.