An electrode for establishing electrical contact with nerve tissue. The electrode is chronically implantable. The outer substrate of the electrode is a semi-rigid, body compatible, insulating material such as a chronically implantable polymer. The outer substrate is molded as a single structure having a central spine along the longitudinal axis of the electrode. A plurality of fingers extend orthogonally from the central spine, and are bent circularly about a radius of curvature approximating that of the nerve to be contacted. Each of the plurality of fingers is of sufficient length to extend approximately one-half of the distance around the outer circumference of the nerve tissue. The plurality of fingers extend from the central spine in one of two opposite directions causing the electrode structure to encompass a hollow cylinder having an inside diameter the same as the nerve. Because the plurality of fingers are not attached to each other, but to the central spine only, and the fingers are semi-rigid, the diameter of the hollow cylinder encompassed by the electrode structure can be readily increased by spreading the fingers during the implantation procedure. Also the diameter of the electrode is expandable to accommodate any swelling of the nerve tissue following implant. The inside surface of the encompassed cylinder is rendered conductive by the bonding or attachment of a conductor to the fingers and/or the central spine. An insertion tool spreads the fingers during the implant procedure and permits a minimum of exposure of the nerve tissue.