Disclosed is a cannula (100) including a first clamping portion (110), a second clamping portion (120) and a force applying portion (130) configured to apply at least two different clamping forces across the first clamping portion and the second clamping portion when the cannula is in a closed state. The first clamping portion includes a first gear (140), the second clamping portion includes a second gear (150), and the first gear and the second gear are in meshing engagement.
