The problem of positioning one or more nerve ends inside a sheathing implant is solved by the use of a pulley and cinching systems that pull a nerve end into an implant and that can adjust the diameter of an implant to conform the implant to the diameter of the nerve, respectively. The pulley system utilizes a suture that traverses the wall of an implant leaving one end outside the implant wall and another end that can be attached to a nerve. Pulling the suture end outside the wall pulls the nerve attached to the other end of the suture into the bore of the implant. A cinching system utilizes specially arranged sutures within the wall of an implant to tighten or cinch up the wall after a nerve is placed therein, so as to conform at least part of the implant to the diameter of the nerve. Methods are also disclosed by which such pulley systems can be formed during an intraoperative procedure.