Is the inside of the vulva exclusively the exit for menses and feces, and would washing the areas beneath the labia minora with one's fingers invalidate the fast?

What is visible of a woman's private parts when relieving herself is considered external, whereas the area where menstruation flows and what lies beneath it is considered internal. If a woman's finger reaches this internal area, her fast is invalidated. The inside of the anus is also considered internal, and scholars have differed on whether inserting a finger into it invalidates the fast.