The only purpose of the figure environment is to allow LaTeX to move the figure, and a minipage inside figure has no purpose at all unless you have footnotes, so you just need
%\begin{figure}
% \begin{minipage}{\textwidth}
\includegraphics[width=75.5mm]{myimage}
% \end{minipage}
%\end{figure}
and the image will appear wherever you have \includegraphics in the source.
Note the rules for placing images are the same as the rules for placing X Normally if you enter X it comes where you put it, either part of the current line, or perhaps indented at start of a paragraph. If you do
\begin{figure}
X
\end{figure}
Then the X will float and be positioned by the page breaking routines. \includegraphics works in exactly the same way, or said more correctly, the float placement routines have no information about the content of the figure environment.