WordPress at a glance
action is not described

admin_head-(hook_suffix) action-hook . WP 2.1.0

Fires in head section for a specific admin page.

The dynamic portion of the hook, $hook_suffix, refers to the hook suffix for the admin page.

Usage

add_action( 'admin_head-(hook_suffix)', 'action_function_name_9631' );
function action_function_name_9631(){
	// action...
}

Where the hook is called

In file: /wp-admin/admin-header.php
admin_head-(hook_suffix)
wp-admin/admin-header.php 135
do_action( "admin_head-{$hook_suffix}" );
wp-admin/includes/template.php 1811
do_action( "admin_head-$hook_suffix" );

Where the hook is used (in WP core)

wp-includes/widgets/class-wp-widget-custom-html.php 80
add_action( 'admin_head-widgets.php', array( 'WP_Widget_Custom_HTML', 'add_help_text' ) );
wp-admin/includes/admin-filters.php 79
add_action( 'admin_head-nav-menus.php', '_wp_delete_orphaned_draft_menu_items' );
wp-admin/custom-background.php 75
add_action( "admin_head-$page", $this->admin_header_callback, 51 );
wp-admin/custom-header.php 80
add_action( "admin_head-$page", array( $this, 'help' ) );
wp-admin/custom-header.php 81
add_action( "admin_head-$page", array( $this, 'take_action' ), 50 );
wp-admin/custom-header.php 82
add_action( "admin_head-$page", array( $this, 'js' ), 50 );
wp-admin/custom-header.php 84
add_action( "admin_head-$page", $this->admin_header_callback, 51 );