Let $M^n$ be a compact manifold, and $F\colon M \to \mathbb{R}^n$ a smooth map. The inverse function theorem implies that every regular value of $F$ lies in the interior of $F(M)$, hence every point on the boundary $\partial F(M)$ is a critical value. Of course it is also possible that a critical value is contained in the interior.
Is there any way of distinguishing critical points that are mapped to the boundary of the image from critical points that are mapped to the interior?