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PREKSHA MEDITATION, THERAPY AND CURES/197
sleep/wake cycle. Connected to the pituitary gland and thus regulates the endocrine system. (Not all authors regard the hypothalamus as part of limbic system.)
Brain, therefore is the unique and indispensable part of the entire body. A person is declared dead when his brain stops functioning. Our activities - conscious, subconscious, automatic and voluntary, all are solely governed by the brain.
1.3. Spinal Cord
It is second most important part of the central nervous system. It extends from the brain stem all the way down to the lower back passing through the vertebral column. It is around 45cm long. Like brain, it is also made up of white and gray matter. Inside white matter are situated ascending and descending fibres. The whole structure of spinal cord is very delicate and its vulnerability is protected by the bony segments of vertebrae and supporting ligaments.
Spinal cord actually works as the two way highway between the brain and the body parts. One lane carries the stimulus information to the brain while the other lane brings down the action commands to various target muscles. In other words, it is an interface between the CNS and PNS.
2. Peripheral Nervous System (PNS)
Our brain has developed an ingenious way to perform all body activities with the help of receptor and effector neuron mechanism. All the limbs and senses are connected to the brain by the peripheral nervous system. PNS is subdivided into --
e Sensory - Somatic Nervous System ia Autonomic - Motor Nervous System
All our conscious awareness of the external environment and all our motor activities to cope with it, operate through the sensory-somatic division of the PNS. Nerves contained in this system are further divided into two main types -
• Cranial Nerves
• Spinal Nerves
Twelve pairs of cranial nerves run to and from the brain and branch out to the muscles and senses of head, face, neck and chest. They participate in eyeball movement, tongue, swallowing, hearing and balance etc.
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