Objectives: The cerebellopontine angle (CPA) poses a surgical challenge due to the complexity
and variation of its associated structures. This study examined the relationship between
the glossopharyngeal nerve (CN IX) and the acousticofacial complex (AFC).
Design: Retrosigmoid suboccipital dissections were preformed on 10 cadaveric specimens. A
triangle formed by the AFC, CN IX, and the skull base was consistently observed. The
cisternal portions of the AFC and CN IX formed two sides of the triangle. The base
was formed by a line traversing the respective dural portals of these nerves at the
skull base. Triangular proportions were used to predict distances from five points
along the course of CN IX to a corresponding point along the course of the AFC.
Results: Predicted distances were not statistically different when compared with cadaveric
measurements in all 10 specimens (P > .05). A table of predicted distances between CN IX and the AFC at all five points
along CN IX was developed, revealing a quantitative model to predict the native location
of the AFC in the lateral pontine cistern.
Conclusion: The triangle and predicted location of the AFC can serve as points of reference for
the identification and preservation of these structures in CPA surgery.
