WP Codex answer incomplete? Put WP in subdirectory. .htaccess change required

Question

I have installed Wordpress in a subdirectory '/medical' and want the address to show up as www.mysite.com/page not www.mysite.com/medical/page

The Wordpress Codex here : https://codex.wordpress.org/Giving_WordPress_Its_Own_Directory says to replace

require('./wp-blog-header.php'); 

with

require('./wordpress/wp-blog-header.php');

but that line does not appear in the generated .htaccess file.

I've tried just inserting the line before the /ifmodule tag but it breaks the site...

Thanks!

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /medical/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /medical/index.php [L]
</IfModule>
# END WordPress

Answer 1

use ths constants for set the install and main domain of WP

define('WP_SITEURL', 'http://www.example.com');
define('WP_HOME', 'http://www.example.com/blog');

i think the htaccess is fine:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /wordpress/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /wordpress/index.php [L]
</IfModule>

the index.php in the root has only an require to the file of the install: require('./wordpress/wp-blog-header.php');