How to add extra menu source and access it in a theme The Menu module contains 2 sources to assign menus to my site.

How do I add a 3rd source? 

Reading through the Zen theme code, I see the variables $main_menu, and $secondary_menu.

I would like to access this 3rd menu source through a variable called $global_menu. 

How do I set this variable from a module?

EDIT

I put this at the bottom of the zen_proprocess_page hook in template.php

$global_menu = menu_navigation_links('menu-global-menu');


and was able to access it with this in page.tpl.php so thank you for that advice 

&lt;?php if ($global_menu): ?&gt;
   &lt;div class="global-navigation"&gt;
      &lt;ul class="nav"&gt;
      &lt;?php foreach ($global_menu as $key =&gt; $value): ?&gt;
        &lt;li&gt;
          &lt;a href="&lt;?php print($value["href"]); ?&gt;" class="global-link" &gt;&lt;?php print($value["title"]); ?&gt;&lt;/a&gt;              
        &lt;/li&gt;
      &lt;?php endforeach;  ?&gt;
    &lt;/ul&gt;
    &lt;/div&gt;
 &lt;?php endif; ?&gt;


EDIT

Moved multipart question to new question
To be able to put it in a theme variable I think you're looking at something like the following.  Please note I haven't tested this, but i should put you in the right direction.

In your template.php or a module:

function MYTHEME_preprocess_page($vars){
  $global_menu = menu_navigation_links('menu-global-menu');
  $vars['global_menu'] = theme('links__menu_global_menu', array('links' =&gt; $global_menu));
}


Then clear your theme registry/caches.