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 rhombencephalon
Prosencephalon or forebrain
developed into telencephalon and diencephalon
telencephalon gives rise to
cerebral hemispheres
basal ganglia
hippocampus
amygdaloid nucleus
diencephalon gives rise to
thalamus
hypo thalamus
metathalamic
subthalamus.
Midbrain or mesencephalon
Gives rise to
tectum tegmentum
cerebral aqueduct
cerebral peduncles
Hind brain or rhombencephalon
developed into metencephalon and myelencephalon
metencephalon gives rise to
pons
cerebellum
the upper part of the fourth ventricle
myelencephalon gives rise to
the lower part of the fourth ventricle
medulla oblongata
Spinal cord
the spinal cord is an extension of the medulla oblongata
it runs in the bony vertebral column
it has outer white matter and inner grey matter
white matter contains all the nerve fibers
grey matter contains cell body of nerve cells
cell bodies and fibers 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 efferent.
spinal nerves from s2 to s4 carries parasympathetic fibers
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 fibers 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 fibers are long
postganglionic neurotransmitters are acetylcholine
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