Several landmarks are utilized here in the search for the main trunk of the facial nerve. The sternocleidomastoid muscle is retracted posteriorly and the parotid gland anteriorly. The posterior belly of the digastric can be visualized as it pushes up into its groove (Figure 4), and the nerve lies anterior to this. The membranous portion of the canal is the superior landmark, and the nerve lies approximately 5 mm from the tip of this cartilage. By using these landmarks as well as a Faradic stimulator or gentle mechanical stimulation with forceps, the surgeon safely can locate the main trunk of the nerve (Figure 5). If mechanical stimulation is used, the instruments must not be clamped firmly on the tissue as a form of testing, but rather the tissue should be pinched gently as the muscles of the face are observed for motion. If an electrical nerve stimulator is used, it must be tested regularly to be certain that it is functioning in each test situation. A final landmark is a branch of the postauricular artery just lateral to the main trunk of the facial nerve. If the position or bulk of the tumor makes exposure of the main trunk of the facial nerve difficult, it may be identified distally. As indicated previously, the marginal mandibular branch lies superficial to the posterior facial vein in most circumstances. The buccal branch lies immediately superior to Stensen's duct, and identification of this duct will lead the operator to the buccal branch of the nerve. Dissection from distal to proximal must be carried out carefully, because the junction of other branches of the nerve may not be seen as easily as divisions of the nerve when the dissection is carried out in the opposite direction.