Why can a spinal injury high in the neck stop breathing when one lower down does not? · Grey Matter

The rhythm of breathing is generated in the medulla, and its commands travel down the spinal cord to the motor neurons of the phrenic nerve, which leave the cord at the third, fourth and fifth cervical segments and drive the diaphragm.

Why can a spinal injury high in the neck stop breathing when one lower down does not?

The rhythm of breathing is generated in the medulla, and its commands travel down the spinal cord to the motor neurons of the phrenic nerve, which leave the cord at the third, fourth and fifth cervical segments and drive the diaphragm. An injury above that level cuts the medulla off from the diaphragm and breathing stops unless a ventilator takes over. An injury below it leaves the diaphragm working, even when the arms or legs are paralysed.