Bill bar

Last revised by Daniel J Bell on 10 Jan 2022

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.

A recent study comparing the ability of a clinical 7 T magnet to distinguish the finer inner ear anatomy, in comparison with a 3 T magnet, found that Bill bar was occasionally visible at both field strengths 4. It has generally not been possible to see on HRCT of the temporal bone.

History and etymology

Bill bar was named after William Fouts House (1923-2012), an American otologist, who was known informally as "Dr Bill".

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