Meaning : The value of Yogasana is greatly enhanced when a sadhaka , while practicing Yogasana , concentrated his mind on spiritual nerve-centres , called Chakras. It is because the mind withdraws itself from all objects of the world & starts concentrating on inner consciousness or what is called Prana Shakti. This practice will prevent the mind from flying into worldly thoughts & objects & stabilize itself on one point of concentration.
There are vital centres in the astral body(Linga Sharir). These have corresponding centres in the spinal cord & the nerve-plexuses in the gross-body. Each Chakra has control & function over a particular centre in the gross-body , that part is inspirited with Prana Shakti while concentrating the mind on these Chakras. As a result , that organ receives a full flow of blood & increased functional capability.
In the union with other organs & communicative nadis , it becomes far more active & far more useful in its effectiveness in that particular part of the body where it is located. By concentrating the mind on these Chakras , both the gross & the subtle bodies are stabilized , which is the chief end & objective of Asanas.
Mooladhar Chakra(Root Chakra) : It is located at the base of spinal column. It helps in excretion of waste matter from the bowel. It is symbol of earth-element.
Swadhishthan Chakra(Sex chakra) : It is located in Sushumna Nadi , behind the root of the genital. It aids the proper management of Nadis. It symbolizes the element of water.
Manipur Chakra(Solar plexus Chakra) : It is located within the Sushumna Nadi , behind the root of the naval. It stimulates the digestive system. It is symbol of the element of fire.
Anahat Chakra(Heart Chakra) : It is located in the spinal column behind the heart. It alleviates the disorders of respiration & skin. It symbolizes the element of air(Vayu).
Vishudhi Chakra(Throat Chakara) : It is situated in the spine behind at the base of the throat. It promotes the melody of the sound. It is centre of ether element(Akash Tattw).
Agya Chakra(Third Eye) : It is situated behind the centre of two eye-brows the place of the sacred mark(Tilak). It helps in the management of brain & glandular system. It controls all energy centres.
Sahasrar Chakra(Crown chakra- Door to God) : It is situated at the crown of the head. It is symbol of the Supreme Bliss or Param Anand.