Skull trephine

摘要

In order to bring about non-functioning in a skull trephine after a predetermined number of uses it is proposed that a locking member be provided between two parts of the skull trephine which are moved to and fro once during each use, the locking member engaging with spring-loaded teeth in the locking recesses of the two parts and being displaceable stepwise up to a terminal stop due to the relative movements of the two parts.