texts claim that there are 72, 000 nadis in the astral body. A layout of these nadis is shown in (Fig-89). Of these innumerable nadis, three of them need to be known. These three nadis control the flow of mind and prana in all the other nadis. These three nadis are Ida, Pingala and Sushumna (Fig-90).

Sushumna Nadi
This is the astral spine, the spine of the energy-body called Pranamaya kosha. It is a hollow tube running from Mooladhara chakra to Sahasrara chakra. Inside the physical spinal cord a hollow canal runs all along the length called canalis centralis. Sushumna nadi is situated inside this hollow canal. It originates at the mooladhara moves inside the spinal cord through the canal centralis and pierces the talu (upper palate) and divides itself into two branchesanterior and posterior. The anterior branch goes to the Agnya chakra the eye-brow center and from there to the Brahmarandhra. The posterior branch passes from behind the head and joins the Brahmarandhra. A yogi aspirant generally has to work with the posterior branch of the Sushumna. The Sushumna nadi encloses within itself another nadi called Vajra nadi. Within this Vajra nadi is Chitra nadi. Vajra Nadi and Chitra nadi correspond to the two bodies called Manomaya kosha and Vijnanmaya kosha. Within Chitra nadi is the subtlest of all the nadis the Brahma nadi. This is the spine of the causal body or Anandamaya kosha. This causal body is made of Consciousness or thought vibrations in the form of ideas. This nadi has seven centers of consciousness the chakras of the causal body. All the chakras are located within this Brahma nadi. For all practical purposes we will take the chakras located within Sushumna because Brahma nadi is itse1f within the Sushumna.

Brahmadwara
The lower opening of the Sushumna nadi is called ‘Brahmadwara' or the door to Brahman. The kundalini energy has to pass through this opening in its ascent upward. The kundalini resides just below this opening and blocking this opening.

Brahmarandhra
The word means, ‘The cave of Brahman'. This refers to the hollow space between the two hemispheres of the brain and is situated at the top of the brain. In medical science this place is known as the anterior fontanel. This hollow space is also known as ‘Bhramara Gufa' ( cave of the bumble bee ) and ‘Andha Kupa' ( the blind well or the tenth gate ). Externally this is the ‘soft spot' that is open when the child is born. In a new born pulsation can be felt at this spot in the first few weeks, after six months it hardens. Thereafter, it is opened only through the practices of Yoga. At the time of death if the soul leaves the body from this point then it is liberated and do not come back for a rebirth
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Ida and Pingala Nadis
These are two major nadis and are located on the left and the right side of the Sushumna. They correspond to the Parasympathetic and Sympathetic nervous system of the physical body. In the physical body Parasympathetic system retards or inhibits all autonomic functions and Sympathetic system stimulates or accelerates. Similarly in the astral body Ida group of nerves has an inhibiting or cooling effect and Pingala group of nerves has a stimulating or heating effect.