The excellence of latter is that its incision can be adjusted optional . 4 . 17 . 5 % of specimens have angled variation of the back wall of petrous bone 约有17 . 5颞骨岩部后骨板有成角变异( 7侧) ，且以后外缘为多。
2.
Ct and mr imaging showed a densely calcified nodule with fatty bone marrow component protruding from the inner surface of petrous bone but not involving the internal auditory canal 电脑断层与磁振造影检查显示一致密钙化结节，内含脂髓，由岩骨内缘凸出，但未侵犯内耳听道。
3.
Ct and mr imaging showed a densely calcified nodule with fatty bone marrow component protruding from the inner surface of petrous bone but not involving the internal auditory canal 计算机断层与磁振造影检查显示一致密钙化结节，内含脂髓，由岩骨内缘凸出，但未侵犯内耳听道。
