| 摘要 |
A cannula including an inner structure, an outer structure, and a flexible portion. The outer structure is disposed about the inner structure and movable with respect to the inner structure. The flexible portion is attached to the inner structure at an end thereof and attached to the outer structure at an end thereof. The flexible portion is adapted to be stretched from a first smaller diameter when the outer structure is in a first position to a larger diameter when the outer structure is in a second position.
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