horizontal segment

The tensor tympani muscle, middle meningeal artery and mandibular nerve are good landmarks to predict and identify the horizontal segment of the internal carotid artery.

鼓膜张肌、脑膜中动脉、下颌神经是预测和辨认颈内动脉水平的良好标志。

The tensor tympani muscle was 2.2 mm in average to the horizontal segment of the petrosal portion of internal carotid. The average distance between the horizontal segment and middle meningeal artery was 6.8 mm, and 6.9 mm to mandibular nerve.

颈内动脉水平段距鼓膜张肌平均为2.2mm，距脑膜中动脉和下颌神经分别平均为6.8mm和6.9mm。

Landmarks for horizontal segment of the facial nerve: the facial nerve tracks forward inferior to short process of incus and anterior to horizontal semicircular canal carina in 30 angel.

面神经水平段标志位于砧骨短突之下；在水平半规管隆突前缘向前上呈30°行走；

Conclusions: Petrous ridge is parallel with horizontal segment of facial nerve.

结论：面神经水平段大致平行于颞骨岩部上嵴，气化的乳突其颞骨岩部后骨板与外耳道后壁之间距离较大；