function menu_switch(){
menu_buttons= $(".menu_button");
jQuery.each(menu_buttons,function(){
var name_length=$(this).attr('src').length;
var imgext =$(this).attr('src').substr(name_length-3,3);
if($(this).attr('src').substr(name_length-7,3)=='off'){
$(this).mouseover(function(){
                                                img_on=$(this).attr('src').substr(0,name_length-7)+"on."+imgext;
                                                $(this).attr("src",img_on);
                                               });
 $(this).mouseout(function(){
                                                img_off=$(this).attr('src').substr(0,name_length-7)+"off."+imgext;
                                                $(this).attr("src",img_off);
                                               });
}
});
}