A vertebral fixing system suitable for being mounted on a vertebra of the spine for connecting it to a rod. The system includes: a connecting part suitable for being connected to the rod, a flexible ligature of elongate shape having two free ends suitable for connecting together the connecting part and at least a portion of a vertebra and/or a rib, and an adjustable locking member mounted on the connecting part. The connecting part defines at least one passageway for passing the ligature in such a manner that two distinct strands of the ligature can be engaged in the passageway so that the two strands of the ligature define a first ligature portion forming a loop extending from one side of the connecting part, and second and third ligature portions extending from the other side of the connecting part.
