A line (as of cord) that has at one end a weight (as a plumb bob) and is used especially to determine verticality.


{{ sagitalbalance.png?400|}}
The [[Scoliosis research society]] (SRS) has previously described 
((Scoliosis Research Society. White paper on sagittal plane alignment))
normal [[sagittal balance]] as occurring when a [[plumb line]] drawn from the centre of the body of C7 lies within ±2 cm of the sacral promontory.