中央前、后回在矢状断面上的定位

目的：在矢状面上利用髓突对成人端脑的中央前、后回进行准确定位。方法：取30例成人头部标本，MR扫描获得层厚6mm的颅脑矢状面MRI图象，然后切制成相应的连续脑切片，二者结合并以钟表盘为参照对髓突进行观察、测量与统计。结果：在旁正中矢状面上，“兔尾征”是中央后回定位的特征性标志。各层面以钟表盘为参照，12点左右是集中辨认中央前回的位置，12点半左右是集中辨认中央后回的位置，且随着层面外移，髓突方向呈现一定的规律：中央前回髓突基本对应12点位，至脑岛外侧份层面时，12点位正好是中央沟，其前后髓突支分别是中央前、后回。再向外切时，中央沟基本保持该方向不变。结论：在矢状面上利用髓突可准确定位中央前、后回。

Localization of pre-and postcentral gyri on sagittal sections

Objective: Localizing pre- and postcentral gyri on sagittal sections by medullary processes. Methods: 30 normal cadaver heads were chosen and then MRI slices thicking 6 mm were obtained in the sagittal plane. After scanning, the brains of cadaver heads were cut into brain slices in correspondence with MR scanning. Medullary processes was observed, measured and described by two kinds of slices according to the reference of the dial plate. Results: On the paramedian section, "rabbit-tail" sign was the key landmark of postcentral gyrus. Referring to the dial plate on every section, the medullary processes of precentral gyrus appeared on the direction of about 12 o'clock and postcentral gyrus on the half past 12 o'clock. In addition, as the sections departing from the medial, the direction of medullary processes's changed regularly. Medullary processes of precentral gyrus almost appeared on the direction of 12 o'clock. On the section cutting through insula, central sulcus located exactly 12 o'clock direction. However, the central sulcus was fixed on the slices passing the insula laterally, the Anterior and posterior medullary processes represented pre- and postcentral gyri respectively. Conclusion: It is accurate to localize the pre- and postcentral gyri according to the pattern of medullary processes.