Editing main menu code

Hi All,

I’m currently using the theme Simplicity (woothemes). In header.php I’m trying to edit the top navigation code to add a <span> around the text in the <a> tag. It seems I can only add a span to the first menu item as it is written out in header.php but I can’t access the rest of the dynamically generated nav items. Is it possible to edit the rest of the nav items to include extra code?

Thanks for your time!

Mark