12. The spinal fixation system of claim 11 , wherein the connecting assembly includes a distal surface that bears against a proximal terminal end surface of each of the opposed arms of the rod receiving portion of the bone anchor.
12. The spinal fixation system of claim 11 , wherein the connecting assembly includes a distal surface that bears against a proximal terminal end surface of each of the opposed arms of the rod receiving portion of the bone anchor. 14. The spinal fixation system of claim 12 , further comprising a subassembly threadably mated to the bone anchor, wherein the subassembly is configured to engage the connecting assembly to mate the spinal rod to the subassembly.