LizAN,
well, I've been searching through my resources in the hopes that I can give you the best answer. As I understand it, the facial nerve only sends sensory to to tongue. "The trigeminal sensory complex is the sensory nucleus for all sensations from the face. All general somatic afferent (GSA) fibers from cranial nerves 5,7,9,10 terminate in some part of the trigeminal sensory nucleus, which includes three nuclei."
That's what my text says. So basically, it means that fibers from the facial n. end on the trigem sensory nucleus, which is a part of the brain that is essential to sensation of the entire face. The sensory nucleus spans almost the entire length of the brain stem, it's huge compared to all the other nuclei. General somatic afferent (GSA) fibers convey pain, temperature, and pressure but they are primarily conveyed by the trigem n. So if the facial nerve gets affected by the tumor, then those fibers from the facial n. that are carrying pain, temp, and pressure (not all of them) to the trigeminal sensory nucleus are affected too causing the numbness.
I really hope this helps, I'm not trying to confuse anyone more.