what is nervous system

What is central nervous system

                                                  INTRODUCTION

• The nervous system is important for the control of many functions ar the body . It is also the communication system of the body . The nervous system is divided into two parts : .

                     1 . The central nervous system includes the brain and spinal cord .

central-nervous-system,spinal-cord

                     2 . The peripheral nervous system includes 12 pairs of cranial nerves                                   with its branches and 31 pairs of spinal nerves and their branches .

cranial-nerves,brain

The nerves can be divided into : 

                    1 . Afferent
                    2 . Efferent

•  Afferent or sensory nerves are those nerves which carry impulses towards the central nervous system .
•  Efferent or motor nerves are those nerves which carry impulses away from the central nervous system . 
• In the embryo the nervous system develops from the neural rube . There are three expansions of the neural tube which appears at the head | end of the tube due to the unequal rates of growth . 
• Each of these Expansions develop into forebrain , midbrain and hindbrain . 
• The rest of l the neural tube becomes the spinal cord .

brain

                  1 . Forebrain : This develops into -

( 1 ) cerebral hemispheres ;
( 2 ) basal ganglia ;
( 3 ) thalamus ; and
( 4 ) hypothalamus

                 2 . Midbrain : The parts of the midbrain are - 

( 1 ) tectum ;
( 2 ) tegmentum ;
( 3 ) cerebral peduncles

                 3.Hindbrain : This develops into - 

( 1 ) cerebellum
( 2 ) pons
( 3 ) medulla