A surgical apparatus includes an elongated cannula having an external sidewall surface and a lumen extending between a cannula proximal regional and a cannula distal region, the cannula is further configured to receive an endoscope, and has a handle located at the cannula proximal region, a first wire extending from the cannula distal region and adapted to slide longitudinally with respect to the cannula in both a distal and proximal direction via a control at the handle, and a ring connected to the first wire. The ring has a curved surface with concavity hollowed towards a region of the cannula configured to receive the endoscope.