An intervertebral implant includes an implant body having superior and inferior sides, medial and lateral sides, and anterior and posterior ends. The superior and inferior sides each include a central section and convex side sections extending from opposite sides of the central section to the medial and lateral sides. The convex side sections are composed of a plurality of convex surface segments of different radii of curvature. The medial and lateral sides each have a concave inward portion and superior and inferior outward portions defining a cavity. An implant inserter includes a pair of holding members for being removably received in the cavities of the implant with an intermediate convex section of each holding member extending between the superior and inferior sides of the implant. The intermediate convex section of each holding member is composed of a plurality of convex surface segments of different radii of curvature.