“Lateral Angle” of the Internal Auditory Canal: Non‐Association with Temporal Bone Pneumatization

Abstract

The "lateral angle," the angle with which the posterior wall of the internal auditory canal meets the posterior fossa plate, is arguably wider in females (>45 degrees) than males (<45 degrees). Not previously addressed, however, are repeatability of angle determination, and whether the extent of temporal bone pneumatization is a confounder. Forty-one adult human cranial specimens (82 clinically normal temporal bones) were studied; no sex information was available for this United States sample. Two casts were created from each ear; each cast was independently categorized twice. No association of lateral angle with mastoid size was found. Repeatability was good. Although bilateral symmetry was suggested (phi = 0.60, p = 0.05), two crania had oppositely categorized right-left angles. We observed a new finding: narrowed but clinically normal canals in 10% of crania. The lateral angle is a good candidate to be a morphological method in determination of sex.