Receiver for inhibiting spreading apart of tooling receiver attachment portions

A receiver of a bone anchor assembly intended for securing an elongate rod to a head of a shank via a closure top and with tooling, the shank including a threaded anchor portion opposite the head configured for implantation into a bone of a patient, the tooling having a pair of spaced apart receiver attachment portions adjacent a lower end thereof, the receiver comprising:

• a pair of integral upright arms extending upward from a base portion to upper portions of the upright arms having a plurality of upwardly-facing arcuate surfaces centered about a vertical centerline axis of the receiver, the upright arms including opposing internal surfaces extending between a forward-facing surface and an backward-facing surface of each upright arm to define an open channel configured to receive the elongate rod, the upright arms further including upper outwardly-facing arcuate surfaces extending downward from the upwardly-facing arcuate surfaces, and inwardly-facing arcuate surfaces spaced outwardly and apart from the opposing internal surfaces, the upper outwardly-facing arcuate surfaces extending down from at least one of the upwardly-facing arcuate surfaces;
• a discontinuous helically wound guide and advancement structure formed into an upper portion of the opposing internal surfaces of the upright arms and centered about the vertical centerline axis to define at least a portion of a central bore of the receiver, the guide and advancement structure extending below the inwardly-facing arcuate surfaces;
• horizontally elongated arcuate tool engagement grooves formed in the upright arms and spaced outwardly with respect to the opposing internal surfaces and configured to at least partially receive the receiver attachment portions, each of the tool engagement grooves including a upwardly-facing groove surface spaced a fixed distance below the upwardly-facing arcuate surfaces of the upright arms and outwardly-facing groove surfaces opposite the opposing internal surfaces, the upwardly-facing groove surfaces and outwardly-facing groove surfaces extending to the forward-facing surface and the backward-facing surface of the upright arms;
• and
• opposite vertical tool-engagement slots extending at least partially between the plurality of upwardly-facing arcuate surfaces of the upright arms and the horizontally elongated arcuate tool engagement grooves,
• wherein when the receiver attachment portions of the tooling are positioned on the receiver, the upper portions of each upright arm are configured to at least partially engage arcuate extending engagement surfaces at the lower ends of the attachment portions of the tooling so as to inhibit outward spreading of the pair of spaced apart receiver attachment portions.