All the nerve bundles of the body are routed through the backbone and are called the spinal :

a : cord
b : vertebrae

you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.

1. is geographic distribution

2 is increasing complexity

3 is transitional forms