A cervical rib is an extra rib that is comes from the neck spine rather than the chest (or thoracic spine). It comes from the last (seventh) cervical vertebra.
0.2-0.5% of the population have this ‘extra rib; and it can be partial (a bit of a rib or a band of tight fibrous tissue rather than bone or complete fully formed bony rib).
The Extra rib makes thoracic outlet syndrome more likely, most people with a cervical rib don’t even know they have it and causes them no problem.
Finding an extra rib when you have no other problems needs no action.