<?php wp_nav_menu( array( 'menu' => 'Primary Navigation', 'container' => '', 'walker' => new rc_scm_walker) ); ?>
<?php //remove this
class rc_scm_walker extends Walker_Nav_Menu
{
      function start_el(&$output, $item, $depth, $args)
      {
           global $wp_query;
           $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

           $class_names = $value = '';

           $classes = empty( $item->classes ) ? array() : (array) $item->classes;

           $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) );
           $class_names = ' class="'. esc_attr( $class_names ) . '"';

           $output .= $indent . '<li id="menu-item-'. $item->ID . '"' . $value . $class_names .'>';

           $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
           $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
           $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
           $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';

            $thumbnail = '';
            if ( has_post_thumbnail( $item->object_id )) {
                $thumbnail = get_the_post_thumbnail_url( $item->object_id, 'medium' );
            }

           $prepend = '<strong>';
           $append = '</strong>';
           $description  = ! empty( $item->description ) ? '<span>'.esc_attr( $item->description ).'</span>' : '';

           if($depth != 0)
           {
	           $description = $append = $prepend = "";
           }

            if($item->description) {
                $customdescription = '<p>' . $item->description . '</p>';
                $customImage = '<div style="background-image:url(' . $thumbnail . ')"></div>';
                $titleWrap = '<span class="title">';
                $titleWrapClose = '</span>';
            } else {
                $customdescription = '';
                $customImage = '';
                $titleWrap = '';
                $titleWrapClose = '';
            }


            $item_output = $args->before;
            $item_output .= '<a'. $attributes .'>' . $titleWrap;
            $item_output .= $args->link_before .$prepend.apply_filters( 'the_title', $item->title, $item->ID ).$append;
            $item_output .= $description.$args->link_after;
            $item_output .= $titleWrapClose . $customImage . $customdescription . '</a>';
            $item_output .= $args->after;

            $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
            }
}