| C1 | first cervical nerve; first cervical vertebra; first component of complement |
|---|---|
| C2 | second cervical nerve; second cervical vertebra; second component of complement |
| C3 | third cervical nerve; third cervical vertebra; third component of complement |
| C4 | fourth cervical nerve; fourth cervical vertebra; fourth component of complement |
| C5 | fifth cervical nerve; fifth cervical vertebra; fifth component of complement |