Figure 3: Anatomical variants and anomalies of the facial nerve (overview, taken from [82]). a.) normal course, b.) subtotal obstruction of the oval window by an overhanging facial nerve, c.) lack of bony cover in the tympanic segment, d.) dehiscent nerve crossing the oval window, e.) herniation of the dehiscent nerve into the middle ear and obstruction of the oval window, f.) elongation of the second genu resulting in a sharp angle between tympanic and mastoidal segment of the nerve, g.) duplication of the tympanic portion, h.) lateralization of the mastoid portion, i.) anterior displacement of the mastoid portion.