In my neuro-anatomy course notes I found that the facial nerve "uses" the trigeminal nerve to reach its targets. However, I have yet to find any diagram or reference that indicates how this is done. How is the trigeminal nerve "used" by the facial nerve?
Certain parts of the facial nerve cooperatively share structure of trigeminal nerve. For example, to reach the sublingual gland, the chorda tympani of the facial nerve joins the mandibular branch of the lingual nerve. Additionally, to reach the lacrimal gland of the eye, the greater petrosal nerve branch of the facial nerve joins the structure of the maximallary branch of the trigeminal nerve.
For a pictorial demonstration of this, please refer to page 1069 of Clinically Oriented Anatomy 7th edition by Moore.