The third line here is a bit long. I muddled over keeping it as trapped, changing it to inscribed, or to keep both. I decided to keep both:
Inscribed helps to lead into the last verse, and give us more of a hint than the "ink" as the final word. It also develops the last line into an actual poetry verse and not just a few words in a line.
Trapped helped me indicate to the readers that the writer was indeed trapped in a cave, however they still retained the freedom of writing their thoughts. That is true freedom. Without this, the readers would only have the first word to indicate that the character was in a cave; hardly enough (as readers normally only trully enjoy the poem starting from the second verse, and to catch that they would need to reread it; you don't enjoy the magic of it nearly as much the second time around) to express that.
So I needed both of these. I also originally had "dried" replaced with "buried" in the last verse, and the writing would be buried, as would the writer. However, the poem only indicated that the person was trapped and not caved in. Among other things, this could lead to quite a bit of confusion without explanation.
