If your document uses Heading Styles for the titles, Word can build a Table of Contents for you (e.g. via Insert|Quick Parts|Field>TOC). If you click on an entry in the Table of Contents, Word will take you to that heading. If you add the hyperlink backward & forward buttons to the QAT, they will take you back to the Table of Contents and forward to the previous heading, respectively.

You can also use Word's Outline View for navigating the document.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]