Patent attributes
A receiver assembly includes a receiver with upright arms extending upward from a base to define an open channel for receiving a rod, and a central bore communicating with a bottom of the base through a bottom opening and having a discontinuous guide and advancement structure proximate the tops of the upright arms. Each upright arm further includes one or more tool engagement grooves extending horizontally and circumferentially below the top of the upright arm to a front or back outer face the receiver. The assembly also includes a closure with a cylindrical outer surface having a continuous guide and advancement structure that is mateable with the discontinuous guide and advancement structure to secure the rod within the open channel without engaging the tops or side outer faces of the upright arms, with the closure top being selected from a single-piece closure body with a solid closed-off bottom surface and two-piece closure body having an outer ring and an inner set screw with a solid closed-off bottom surface.
