The nerves or neurons within the spinal cord are not the only cells, which communicate through chemical and electrical methods.  There three types of glial cells within the brain and spinal cord. These are astrocytes, microglia, and oligodendrocytes.

The most prevalent type is the astrocyte.  They tend to outnumber neurons in the brain and the spinal cord by as much as 10 to 1. Astrocytes form the framework and support tissue of the brain and spinal cord.  The glial cells help deliver nutrients to the nerves.  They also modulate nerve signals and respond to spinal injury or ischemia.