Patent ID: 8043319

Claim:
A cannula assembly, comprising: a first tube having a first diameter, a proximal end and a distal end; and a second tube having a second diameter greater than the first diameter, a proximal end and a distal end; the second tube further comprising a plurality of spaced apart flexibly movable members positioned on the distal end of the second tube, the plurality of flexibly movable members being circumferentially disposed about and longitudinally co-extensive with the second tube and secured to the distal end of the second tube; the second tube further comprising an advancement mechanism provided on the proximal end of the second tube, the advancement mechanism comprising an open ramp with a continuous helical outer surface at a most proximal end of the second tube, wherein the open ramp is configured to allow a fluid port of the first tube to move along the continuous helical outer surface and to rotate on the open ramp of the second tube, and securely engage and rest within a detent of the open ramp, to move one of the first and second tubes relative to the other one of the first and second tubes in at least one direction.