Vertebral anchoring device and its blocking device on a polyaxial screw

The vertebral anchoring device according to the present invention comprises a connector ( 2 ), a connecting rod ( 10 ) and a polyaxial anchoring screw ( 3 ) comprising a spherical head ( 15 ) and a screw-threaded body ( 16 ) whose external diameter d at a summit of the screw threads ( 17 ) is greater than the external diameter a of the spherical head ( 15 ), each connector ( 2 ) being constituted by a connecting element ( 4 ) comprising vertical branches ( 5, 6 ) delimiting an opening ( 7 ) of U shape, and by a locking clip ( 8 ) provided with a pressure screw ( 9 ) for blocking in the bottom of the U the connecting rod ( 10 ), said connecting element ( 4 ) being pierced at its middle with a vertical bore ( 11 ) permitting receiving opposite the opening ( 7 ) a blocking device ( 19 ) formed by a ring ( 20 ) and a screw-threaded socket ( 21 ) for the emplacement and positioning of the connector ( 2 ) on the spherical head ( 15 ) of the anchoring screw ( 3 ).