Safety needle containment

Safety needle containment for a needle structure comprising a hub and a projecting needle, said containment comprising a needle sheath normally covering the needle before and after use, said sheath comprising a tubular element sized to enclose said needle and having a wall adapted to be grasped by fingers at a locus midway along its length for withdrawal and insertion of said needle, and a disc element mounted transversely on said sheath tubular element above said locus, said disc element being resistant to needle penetration and projecting laterally of said sheath tubular element a distance to clock said syringe needle from reaching said fingers gripping said sheath tubular element below said disc, said disc element defining an over-center structure adapted to snap between said parallel and transverse positions relative to said sheath tubular element responsive to flexing of the sheath tubular element wall below said disc element.