A system for minimally invasive medical procedures includes an elongate tubular access cannula comprising an elongate tubular member having a rigid proximal portion and an articulating portion. The tubular member has a first branch and a tubular bifurcation extending from the first branch, allowing simultaneous use of multiple instruments. A dissector suitable for use with the access cannula, or other access devices, for implantation of gastric bands or for other procedures includes a pre-curved distal portion having a dissection element such as a monopolar RF conductor and/or a dissection balloon, as well as a snare. In one method, the dissector is advanced around the posterior side of the stomach to form a tunnel in the connective tissue, and the snare is then extended from the dissector to engage a portion of the band and withdraw it through the tunnel.