Reproducing an article for your reference:
Nadis: Sushumna Nadi
By Sri Swami Sivananda


When we study the construction, location and function of the Spinal Cord and the Sushumna Nadi, we can readily say that the Spinal Cord was called Sushumna Nadi by the Yogins of yore. The Western Anatomy deals with the gross form and functions of the Spinal Cord, while the Yogins of ancient times dealt with all about the subtle (Sukshma) nature. Now in Kundalini Yoga, you should have a thorough knowledge of this Nadi.



Sushumna extends from the Muladhara Chakra (second vertebra of coccygeal region) to Brahmarandhra. The Western Anatomy admits that there is a central canal in the Spinal Cord, called Canalis Centralis and that the cord is made up of grey and white brain-matter. Spinal Cord is dropped or suspended in the hollow of the spinal column. In the same way, Sushumna is dropped within the spinal canal and has subtle sections. It is of red colour like Agni (fire).



Within this Sushumna th ...more

Base of main chakra which arouse at seat ofmeditation to lighten the body and some will becomeso weight lkess they get lavented andthey are called paramahansa this istaughtin rajayoga

In the spinal canal there are 3 nadis: Ida, Pingala and Sushumna. Normally the sushumna is closed, locked. Only by intense meditation practise or by grace of shaktipath initiation given by a guru it will open a bit. Sushumna is the energy canal for spiritual experience.