didn't think that this is a complex problem but I didn't get it solved.
I'ld love to point www.mydomain.com/phpMyAdmin/ to /var/www/phpMyAdmin/htdocs/
I did this:
server {
    listen 80;
    server_name     localhost;
    location /phpMyAdmin {
            root    /var/www/phpMyAdmin/htdocs/;
            index   index.php;
            #access_log      /var/www/phpMyAdmin/logs/access.log;
            #error_log       /var/www/phpMyAdmin/logs/error.log;
    }
    location ~ \.php$ {
            include fastcgi_params;
            try_files $uri =404;
            fastcgi_pass unix:/var/www/sockets/www.socket;
    }
}
But the result when calling www.mydomain.com/phpMyAdmin ist that it tries to call
/var/www/phpMyAdmin/htdocs/phpMyAdmin/index.php
Anyone could help me?
 
    