Helpful and unhelpful parts of the superior petrosal triangle

The root of zygoma–head of malleus line may guide to the internal auditory canal, but few anatomic studies address its accuracy. The precision of measurements is excellent, the “superior petrosal triangle” components (foramen spinosum, root of zygoma, and head of malleus) have a consistent relationship and accurately guide to Bill’s bar, and distances correlate with pneumatization. Forty-one bequeathed adult human cranial base specimens (82 temporal bones) were dissected in a surgical manner. Measurements had excellent repeatability. The root of zygoma–head of malleus reference line always projected onto or posterior to Bill’s bar, but distances measured had wide ranges. No measurement correlated with pneumatization. The root of zygoma–head of malleus line extends onto or posterior to Bill’s bar. Measurement guides to the head of the malleus are not predictable.