basics of Nervous system exam notes

Introduction

Nervous system controls all the activities of the body. It is quicker than other control system in the body, namely endocrine system.

group of nerves travelling in CNS are called pathway or tracks

a group of cell bodies of neuron in PNS
are called ganglia

Primarily, nervous system is divided into two parts:  

1. Central nervous system 

                 -consist of brain and spinal cord

2. Peripheral nervous system.

           - 12 pair of cranial nerves

           - 31 pair of spinal nerves

3.Autonomic nervous system

              -sympathetic and parasympathetic divisions

Central nervous system

Central nervous system (CNS) includes brain and spinal cord. 

Anatomy of brain:

it is divided into 3 main divisions:

1. forebrain or prosencephalon 

2. midbrain or mesencephalon

3.hindbrain or rhombencephlon

Prosencephlon or forebrain 

developed into telencephalon and diencephalon

telencephalon gives rise to  

1. cerebral hemispheres
2. basal ganglia
3. hippocampus 
4. amygdaloid nucleus

diencephalon gives rise to 

1. thalamus
2. hypo thalamus
3. metathalamus 
4. subthalamus.

Midbrain or mesencephalon

Gives rise to 

1. tectum tegmentum
2. cerebral aqueduct 
3. cerebral peduncles

Hind brin or rhombencephalon 

developed into metencephalon and myelencephalon 

metencephalon gives rise to 

1. pons 
2. cerebellum 
3. the upper part of the fourth ventricle

myelencephalon gives rise to 

1. the lower part of the fourth ventricle 
2. medulla oblongata

Spinal cord

the spinal cord is an extension of the medulla oblongata 

it runs in the bony vertebral collum

it has outer white matter and inner grey matter 

white matter contains all the nerve fibres 

grey matter contains cell body of nerve cells

cell bodies and fibres collectively form the nerve track 

inputs reach the brain through sensory tracks of the spinal cord

spinal cord gives out segmental nerves 

there are 31 spinal segments with 31 pairs of nerves

• cervical        8 
• thoracic        12 
• lumbar          5
• sacral            5 
• coccygeal      1

A typical spinal nerve is a mixed nerve with a sensory division located in the dorsal root ganglion.

the ventral division is motor and carries somatic efferent to muscles

Anterior root of the spinal cord from T 1 to L2 carries sympathetic efferents

spinal nerves from s2 to s4 carries parasympathetic fibres

Peripheral nervous system

The peripheral nervous system (PNS) is formed by neurons and their processes present in all regions of the body. 

It consists of cranial nerves, arising from brain and spinal nerves, arising from the spinal cord. 

It is again divided into two subdivisions:

 1. Somatic nervous system 

 2. Autonomic nervous system.

1. Somatic Nervous System 

 It includes the nerves supplying the skeletal muscles. 

The somatic nervous system is responsible for muscular activities and movements of the body. 

postganglionic fibres are short 

postganglionic neurotransmitters are noradrenaline

2. Autonomic Nervous System

 The autonomic nervous system is concerned with the regulation of visceral or vegetative functions.

 Autonomic nervous system consists of two divisions, sympathetic division and parasympathetic division. 

 

postganglionic fibres are long

postganglionic neurotransmitters are acetylcholine