In the internal acoustic meatus (IAM), Bill's bar is a vertical bony crest that separates which two structures at the fundus?

• A Cochlear nerve from inferior vestibular nerve
• B Facial nerve from cochlear nerve
• C Inferior vestibular nerve from cochlear nerve
• D Superior vestibular nerve from facial nerve ✓

Explanation

At the fundus of the IAM, the horizontal crest (crista transversa / falciform crest) divides the canal into superior and inferior compartments. In the superior compartment, Bill's bar (vertical crest) separates the facial nerve anteriorly from the superior vestibular nerve posteriorly. The inferior compartment contains the cochlear nerve anteriorly and the inferior vestibular nerve (saccular nerve) posteriorly. Accurate knowledge of this arrangement guides surgery for vestibular schwannoma and cochlear implantation.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.