The nervous system is made up of two types of cells- the neurons or the structural and functional units of the nervous system, and the neuroglia or the supporting cells. Neurons are highly specialized cells which carry out the functions of nervous system by transmitting information in the form of nerve impulses, from one part of the body to another, through complex pathways involving synapses. There are more than 10000 million neurons in the nervous system of man, which are formed during their fetal life.
After birth the neurons do not divide. They can only grow and establish connections. But the wearing out of neurons is common. Since neurons can never be grown after a human has been born, a person suffering from a degenerative neuronal disease usually falls prey to gradual death. With the growth and development of the infant after birth, the neurons increase in length and new synapses are formed. This means that more complex neural connections take place, for development of higher neural functions like learning memory etc. Neuroglia cells support and nourish the neurons. They continue to multiply after birth, and areabout 10times more in number than the neurons. The nervous system is anatomically divided into two main parts- the central nervous system and the peripheral nervous system.
The central nervous system comprises of the brain and the spinal cord which lie in the axial part of the body, and remains protected by the bony covering of cranium or the brain box and the vertebral column respectively. The brain is also known as the encephalon. It is the upper expanded part of the CNSlying within the cranial cavity. The peripheral nervous system however includes all the different nerve pathways of the body outside the brain and the spinal cord. Thesepathways connect the central nervous system with various parts of the body extending up to the periphery. The PNS comprises of 43 pairs of nerves. Among these 12 pairs of peripheral nerves are connected to the brain, and the known as the cranial nerves. The remaining 31 pairs of peripheral nerves are connected to the spinal cord. Since onepair is connected to each segment of the former, hence they are known as the spinal nerves.
Stem cell treatment for spinal cord injury in India has a high success rate. Stem cell treatment is very effective in cases where injuries can lead to total destruction in the equilibrium of the motor and sensory functions of the body. The stem cells which are incorporated into the spinal cord grow into new cells in no time and restore the normal body functioning. Spinal cord acts as a centre for various reflexes. The organs supplied by spinal motor neurons are reflex controlled by spinal cord.
The white matter of spinal cord contains ascending and descending nerve tracts, which connects the brain with the peripheral organs except those in the head region innervated by the spinal nerves. 31 pairs of spinal nerves are grouped as 8 cervical, 12 thoracic, 5 lumbar, 5sacral and 1 coccygeal.