Introduction to the nervous system

Nervous system 

The human nervous system, by far the most complex system in the human body, is formed by a 

network of more than 100 million nerve cells (neurons), assisted by many more glial cells. 

* The body’s primary communication and control system.

 Can be divided according to :

1\ Structural categories

2\ Functional categories 

¤ Structural divisions of the nervous system :

1- Central nervous system (CNS) Brain and spinal cord.2-Peripheral nervous system (PNS) Cranial nerves (nerves that extend from the brain) Spinal nerves (nerves that extend from the spinal cord) Ganglia (clusters of neuron cell bodies located outside the CNS).