鼓环 - Anulus tympanicus
The tympanic ring is an incomplete circle, in the concavity of which is a groove, the tympanic sulcus, for the attachment of the circumference of the tympanic membrane.
This ring is still open in the newborn and expands laterally to form the tympanic part of temporal bone. It ossified in membrane from a single center which appears about the third month.
大体解剖 > 骨, 骨骼系统 > 中轴骨骼 > 颅 > 颞骨 > 鼓部 > 鼓环