How do I get the name of a WP admin submenu?

How do I get the name of a WP admin submenu?

I am working with WP 3.5 and have used the following line to add a sub menu:
add_submenu_page('lingo_menu', 'Manage Units', 'Manage Units',
'manage_options', 'lingo_manage_units_menu', 'lingo_manage_units');
And, of course I have a function called 'lingo_manage_units()'.
I would like to redirect all my sub menu calls through one single function
where a switch statement will determine what to do. However, I am not sure
how to get the name of the submenu page that was called.