The canal of the posterior ampullar nerve: an important anatomic landmark in the posterior fossa transmeatal approach

The canal of the posterior ampullar nerve is located between the inferior p art of the internal acoustic meatus and ampulla of the posterior semicircul ar canal. It permits a more accurate localisation of the underlying labyrin th in inner-ear surgery. An anatomical and radiological study was undertake n to determine the importance the relationship between the canal and the la byrinth. Ten dry and 10 cadaveric temporal bone dissections, together with 20 high resolution CT scans of the same temporal bones were studied in an a ttempt to describe the anatomy of the canal of the posterior ampullar nerve . The length of the canal of the posterior ampullar nerve, the length of in ternal acoustic meatus. and distances from porus acusticus to the singular foramen and the transverse crest, and from the singular foramen to the vest ibule and transverse crest, and from operculum to the sigmoid sinus and to the porus acusticus were measured. During the transmeatal posterior cranial fossa approach using the canal of the posterior ampullar nerve as a landma rk enables more bone to be safely removed from the internal acoustic meatus thus preserving hearing.