Apache / AliasMatch / Regular Expressions Help

Not knowing much in the realm of regular expressions, I hope somebody may be able to help me out with something.

I'm trying to set an AliasMatch directive in my apache httpd.conf file. What I want to do is have anything typed after a certain directory automatically pulls from a specified directory - something like this:

http://www.mysite.com/myapp/test
http://www.mysite.com/myapp/demo
http://www.mysite.com/myapp/sample

So everything after "myapp" would automatically resolve to pull from my /www/mysite/myapp directory.

Does that make sense? I tried it with a single Alias command:

Alias /myapp/test "/www/mysite/myapp"

And that worked fine - what I want to do is make it a regular expression so I don't have to add an Alias directive for each directory after "myapp"

Thanks for any help!

Try something along the lines of:
AliasMatch ^/myapp(.*) "/www/mysite/myapp$1