With certain shapes of or canula, elongated caps are made to cover both canula and threaded portion, and seal the canula at its top. 根据管口和导管的不同形状,可以制造细长的管盖以覆盖导管和螺纹部分,并在顶部封住导管。
A cannula (from Latin "little reed"; plural cannulae or cannulas) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data. In simple terms, a cannula can surround the inner or outer surfaces of a trocar needle thus extending the effective needle length by at least half the length of the original needle.