Advertisement

The Central Nervous System (CNS)

        The central nervous system is a delicate structure composed of the brain and the spinal cord. The brain is protected by a bony structure called the cranium or  skull and the spinal cord by the vertebral column or the back bone. Protective membranes called the meanings are present in the space between the soft CNS and the bone. There are cavities present on the different parts of the brain known as ventricles while the long cavity of the spinal cord is called the central canal. The ventricles, central canal and the space between the meanings are filled with cerebrospinal fluid (CSF). CSF keeps the CNS well nourished and also protects it by absorbing mechanical shocks.

Many of our actions are voluntary in nature i.e. we think before doing it, like walking, clapping hands, bending down to pick up something, etc. In all these actions there is involvement of our muscles. The brain sends message to the muscles and the muscles act accordingly. This is the second instance where the nervous system is communicating with the muscles. Such a communication between  the central nervous system and the other parts of the body is brought about by the Peripheral Nervous System (PNS) which is composed of cranial nerves arising from the brain and the spinal nerves arising from the spinal cord. The brain makes us think and we act based on our thinking. We infer that the brain must be a complex structure with different centres responsible for integrating various inputs and outputs. The brain is a complex organ divided in three regions forebrain, midbrain and the hind brain.

        The forebrain or the cerebrum is the main thinking part of the brain. It has regions which receive the sensory impulses from various receptors.