It means that in the lower part pedicular screws must be introduced at a more convergent angle than in the upper part if we do not want to break any cortical of the vertebral body.

• 这意味着，假如我们不想打坏椎体的骨皮质，在椎弓根的下半部打入椎弓根螺钉时的汇聚角必须比上半部大。