Bill’s Bar

Bill’s bar is a bony crest within the internal auditory canal (IAC) that divides the superior aspect of the IAC into an anterior and posterior compartment.¹²
- Anterior to Bill’s bar is the facial nerve proper and nervus intermedius (also known as the Nerve of Wrisberg)
- Posterior to Bill’s bar is the superior vestibular nerve.
- It is named after William House, who is often considered the ”Father of Neurotology”.
Bill’s bar can be contrasted with the falciform crest, which divides the IAC into a superior and inferior compartment.
The combination of Bill’s bar and the falciform crest divide the internal auditory canal into 4 compartments:
- Antero-superior: Facial nerve proper and nervus intermedius
- Antero-inferior: Cochlear nerve
- Postero-superior: Superior vestibular nerve
- Postero-inferior: Inferior vestibular nerve.
A common mnemonic to remember the relative positions of the facial nerve and cochlear nerve within the IAC is “7-up, Coke down”.

Bill's Bar Anatomy of the Internal Auditory Canal

House, William F., Gale Gardner, and Richard L. Hughes. “Middle cranial fossa approach to acoustic tumor surgery: unilateral acoustic tumors confined to internal auditory canal.” Archives of Otolaryngology 88.6 (1968): 631-641. ↩
Bunch, Paul M. “Anatomic eponyms in neuroradiology: head and neck.” Academic radiology 23.10 (2016): 1319-1332. ↩

Last updated October 17, 2022