See these upstream bugs:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/606238
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/678103
The N5040 model is mentioned as not working with Ubuntu 11.10 (the base for
Trisquel 5.5) in the second link.
It looks like you are using an Alps touchpad, which the Linux kernel doesn't
have very good support for. You could try updating your kernel to see if that
fixes anything.
You can use a backported kernel from one of these sources:
http://jxself.org/linux-libre/
https://launchpad.net/~linux-libre/+archive/ppa
If that doesn't work then maybe the best you can do is get a USB mouse for
your laptop. It might not ideal, but at least it will be usable.
