Kanda
This is situated between the anus and the root of the reproductory organ. It is like the shape of an egg and is covered with membranes. This is just above the Muladhara Chakra. All the Nadis of the body spring from this Kanda. It is in the junction where Sushumna is connected with Muladhara Chakra. The four petals of the Muladhara Chakra are on the sides of this Kanda and the junction is called Granthi-Sthana, where the influence of Maya is very strong. In some Upanishads you will find that Kanda is 9 digits above the genitals.
Kanda is a centre of the astral body from where Yoga Nadis, subtle channels, spring and carry the Sukshma Prana (vital energy) to the different parts of the body. Corresponding to this centre, you have ‘Cauda equina’ in the gross physical body. The spinal cord extending from the brain to the end of the vertebral column tapers off into a fine silken thread. Before its termination it gives off innumerable fibres, crowded into a bunch of nerves. This bunch of nerves is ‘Cauda equina’ in the gross body. The astral centre of ‘Cauda equina’ is Kanda.
Spinal Cord
The central nervous system consists of the brain and the spinal cord, the cerebro-spinal centre or axis. The continuation of the Medulla oblongata or the Bulb is a connecting medium between the brain and the spinal cord. The centre in the Medulla oblongata is closely connected with the involuntary functions of breathing and swallowing. The spinal cord extends from the top of the spinal canal to the second vertebra of the coccygeal region where it tapers off into a fine silken thread, called Filum terminale.
The spinal cord is a column of very soft grey and white brain-matter. The white matter is arranged on the sides of the grey matter. The white matter is of medullated nerves while the grey is of nerve-cells and fibres. This is not tightly fitted with the spinal canal, but suspended or dropped, as it were, into the spinal canal just like the brain in the cranial cavity. This is nourished by the membranes. Spinal cord and brain float in the cerebro-spinal fluid. The fluid prevents, therefore, any injury done to them. Further the spinal cord is protected by a covering of fatty tissue. It is divided into two symmetrical halves by an anterior and posterior fissure. In the centre there is a minute canal, called canalis centralis. Brahmanadi runs along this canal from the Muladhara to Sahasrara Chakra. It is through this Nadi, Kundalini, when awakened, passes to Brahmarandhra.
The spinal cord is not divided or separated from the brain. It is continuous with the brain. All the cranial and spinal nerves are connected with this cord. Every nerve of the body is connected with this. The organs of reproduction, micturition, digestion, blood-circulation, respiration are all controlled by this spinal cord. Spinal cord opens out into the fourth ventricle of the brain in the medulla oblongata. From the fourth ventricle it runs along the third, then the fifth ventricle of the brain and finally it reaches the crown of the head, Sahasrara Chakra.
Sushumna Nadi
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 there is a Nadi by name Vajra which is lustrous as Surya (sun) with Rajasic qualities. Again within this Vajra Nadi, there is another Nadi, called Chitra. It is of Sattvic nature and of pale colour. The qualities of Agni, Surya and Chandra (fire, sun and moon) are the three aspects of Sabda Brahman. Here within this Chitra, there is a very fine minute canal (which is known as Canalis Centralis). This canal is known as Brahmanadi through which Kundalini, when awakened, passes from Muladhara to Sahasrara Chakra. In this centre exist all the six Chakras (lotuses, viz., Muladhara, Svadhishthana, Manipura, Anahata, Vishuddha and Ajna).
The lower extremity of the Chitra Nadi is called Brahmadvara, the door of Brahman, as Kundalini has to pass through this door to Brahmarandhra. This corresponds to Haridwar which is the gate of Hari of Badrinarayan in the macrocosm (physical plane). The Chitra terminates in the Cerebellum.
In a general sense the Sushumna Nadi itself (gross Spinal Cord) is called Brahma Nadi because, Brahma Nadi is within the Sushumna. Again the canal within the Chitra is also called Sushumna, because the canal is within the Sushumna. Ida and Pingala Nadis are on the left and right sides of the spine.
Chitra is the highest and most beloved of the Yogins. It is like a thin thread of lotus. Brilliant with five colours, it is in the centre of Sushumna. It is the most vital part of the body. This is called the Heavenly way. It is the giver of Immortality. By contemplating on the Chakras that exist in this Nadi, the Yogi destroys all sins and attains the Highest Bliss. It is the giver of Moksha.
When the breath flows through Sushumna, the mind becomes steady. This steadiness of the mind is termed “Unmani Avastha”, the highest state of Yoga. If you sit for meditation when Sushumna is operating, you will have wonderful meditation. When the Nadis are full of impurities, the breath cannot pass into the middle Nadi. So one should practise Pranayama for the purification of Nadis.
Para-Sympathetic And Sympathetic System
On either side of the spinal cord run the sympathetic and para-sympathetic cords, a double chain of ganglia. Ganglia means a collection of nerve-cells. These constitute the Autonomic System which supplies nerves to the involuntary organs, such as heart, lungs, intestines, kidneys, liver, etc., and controls them. Vagus nerve which plays a vital part in human economy comes out of this sympathetic system. Sympathetic system stimulates or accelerates. Para-sympathetic system retards or inhibits. There are nerves to dilate or expand the arteries which carry pure oxygenated blood to nourish the tissues, organs and cells of different parts of the body. These are called Vaso-dilators. The left and the right sympathetic chains are connected by filaments. These cross from the right to the left side and vice versa, but the exact places where these crosses are not known, though several have attempted to find. M’Kendrick and Snodgrass in their Physiology of the Senses write: “Where the sensory fibres cross from one side to the other is not known ….. In some parts of the spinal cord the sensory fibres do cross from the right to left side and vice versa.”
