不确定这是否足够健壮，但它显示了通过菜单的基本遍历，首先查找当前帖子，然后再查找其菜单父项：

/**
 * @param mixed $menu
 * @param int   $post_id
 *
 * @return WP_Post|bool
 */
function get_menu_parent( $menu, $post_id = null ) {

    $post_id        = $post_id ? : get_the_ID();
    $menu_items     = wp_get_nav_menu_items( $menu );
    $parent_item_id = wp_filter_object_list( $menu_items, array( \'object_id\' => $post_id ), \'and\', \'menu_item_parent\' );

    if ( ! empty( $parent_item_id ) ) {
        $parent_item_id = array_shift( $parent_item_id );
        $parent_post_id = wp_filter_object_list( $menu_items, array( \'ID\' => $parent_item_id ), \'and\', \'object_id\' );

        if ( ! empty( $parent_post_id ) ) {
            $parent_post_id = array_shift( $parent_post_id );

            return get_post( $parent_post_id );
        }
    }

    return false;
}