Device used to insert cannula into vein, comprises a tab (11) molded on a moveable component, including a wall penetrated by a hole (12) allowing the needle to pass through. The wall is held in a sliding mounting, allowing the wall to slide transversely to a release position, so when the needle is retracted and set back into the recess, the tab can be raised, allowing the cage unit to be separated from the cannula (1) base (2). Device used to insert cannula into vein, comprises a tab (11) molded on a moveable component (9, 10). This includes a wall (10) penetrated by a hole (12) allowing the needle (3) to pass through, holding the tab in position. The wall is held in a sliding mounting, in the chamber (13) of the cage unit (5). This mounting allows the wall to slide transversely with respect to the needle (when the latter is removed), to an upper, released position. Thus when the needle is retracted and set back into the recess, the tab can be raised, allowing the cage unit to be separated from the cannula (1) base (2).
