"Bill bar (TA: crista verticalis) also known as the vertical crest, is a bony anatomical landmark that divides the superior compartment of the internal acoustic meatus into an anterior and posterior compartment. Anterior to Bill bar, in the anterior superior quadrant, are the facial nerve (CN VII) and nervus intermedius, and posterior to it, in the posterior superior quadrant is the superior division of the vestibular nerve (see figure 1). The upper quadrants are separated from the lower quadrants by the falciform crest."