Patent ID: 8439881

Claim:
A surgical access device, comprising: a) a cannula adapted for insertion through the wall of an anatomic structure, the cannula comprising a distal tube having a wall with a thickness defined by medial and lateral surfaces; at least one opening in the distal tube medial surface; a proximal tube located adjacent the distal tube; b) an obturator adapted to be inserted into the distal and proximal tubes, the obturator having a lock adapted to engage the opening; c) an anchor disposed about the distal tube; d) a button assembly in the obturator in communication with the anchor wherein distal movement of the button collapses the anchor about the distal tube; and e) a raised helical surface on the proximal tube adapted to engage a helical impression on the distal tube medial surface wherein rotation of the obturator relative to the proximal tube drives the distal tube over the proximal tube.