11. In a bone anchor, the improvement comprising: a) a shank having a body for fixation to a bone and an integral upper substantially spherical head having a first radius; b) a receiver having a base, a first pair of upright arms and an outer surface, the receiver upright arms defining an open channel, the base defining a chamber and a lower opening, the chamber communicating with both the channel and the lower opening, each arm having a through aperture formed therein; c) at least one insert disposed within the receiver chamber, the insert having a surface sized and shaped for frictional mating cooperation with the shank head, the insert further having a second pair of upright arms, each arm having an outwardly extending wing, each wing extending through one of the apertures of the receiver, the wings being engageable by tooling placed adjacent to the receiver outer surface for movement of the insert both toward and away from the shank head; and d) a resilient open retainer having a base, the retainer captured within the chamber and expandable about at least a portion of the shank head and wherein expansion-only locking engagement occurs between the shank upper portion and the retainer base and between the retainer base and the receiver, the retainer having a concave second substantially spherical surface with a radius smaller than the radius of the shank head, the second surface terminating at upper and lower edges, the edges temporarily frictionally mating with the shank head, providing a friction fit between the retainer and the shank head during non-locking angular manipulation of the shank with respect to the receiver.
13. The improvement of claim 11 wherein the insert has an outer surface releasably frictionally locked against the receiver.