The ten नाडीस् where the योगी in meditation retains the five प्राणस् form the नाडिचक्र .

At the bottom of the नाभि ( नाभीकन्द ) innumerable नाडीस् or nerves originate or sprout up. 72,000 such नाडीस् exist at the centre of the नाभि (navel). The whole body is filled with these नाडीस् spread out in parallel and horizontal positions, and they exist in the form of circles entwined with one another. Ten नाडीस् are prominent amongst them, that is इडा , पिङ्गला , सुषुम्ना , गान्धारी , हस्तिजिह्वा , पृथा , यशा , अलम्बुषा , कुहा and शङ्खिनी . Any defect or harm caused to any one of these ten नाडीस् may lead even to death.

There are ten वायु s (winds) in the body. The five प्राण s called प्राण , अपान , समान . उदान and व्यान , and the five वायु s called नाग , कूर्म , कृकल , देवदत्त and धनञ्जय together constitute the ten वायु s. प्राण is the most important वायु . This वायु does the emptying as well as the refilling of the other nine वायु s and thus sustains life. The प्राणवायु has its existence ever in the chest of living beings and fills the body with air through breathing in, out, coughing etc. It depends on life and it is called प्राणवायु as it moves or travels with life.

अपान leads वायु downwards. It is अपान which directs man's food downwards. Also it keeps in its fold urine and semen. This वायु is called अपान as its function is अधोनयन (leading downwards) as mentioned above. समानवायु conveys to the different parts in the body in equal manner the things which living beings eat, drink and smell as also blood, bile, phlegm and वात . उदान causes the shivering of lips, flushing of face and eyes and excitement of joints etc. व्यान causes the limbs to be closed and stretched, and it excites diseases. नाग exists in nausea, कूर्म in the bulging of the eyes कृकल in food, देवदत्त in yawning and धनञ्जय in sound. धनञ्जय does not quit the body even after death.

Life, प्राण , travels through the नाडीचक्र depending on ten different courses, that is सङ्क्रान्ति , विषुव , अहर् , रात्रि , the two ayanas ( दक्षिण and उत्तर ), अधिवास ऋण , ऊनरात्र and धन . ऊनरात्र means hiccough, ऋण cough, धन breathing and अधिवास yawning. Of the two ayanas, उत्तर and दक्षिण , the former is the course towards the left and the latter towards the right and विषुव is the centre between the two. सङ्क्रान्ति is the change of position of विषुव . On he left side of the human body is the नाडी called इडा , on the right side पिङ्गला and between the two सुषुम्ना . The प्राण above these three नाडीस् is अहर् that is day and that below is अपान , that is night. Thus every वायु assumes ten different forms.

There are various kinds of प्राणायाम (control of breaths). प्राणायाम practised with the प्राण contained in the centre of the body is called चन्द्रग्रहण ; that which supersedes physical principles is called सूर्यग्रहण . To fill the stomach with as much of वायु as is desired is पूरकप्राणायाम . To remain like a full pot, all breathing stopped, (Pot completely filled) having closed all the openings--'doors'--of the body is कुम्भक . The योगी practising कुम्भक should direct the वायु upwards in one breath, and that practice is called रेचक . He who does it should be conversant with the yoga of inhalation. Erudite people call it जप , because when it is practised शिव resident in one's own body awakes within. शिव , the King of योगिन्स् , chants the mantra ( जप ) 21,6000 times within the course of one day and one night. The soul chants the mantra- गायत्री --of which ब्रह्मा, विष्णु and शिव are the presiding deities, and that is called अजप . He who chants अजप will have no future births. प्राणायाम should be followed by कुण्डलिनीयोग , कुण्डलिनी meaning primordial force. The force is a compound of Sun, fire and Moon and its seat is the heart, where it exists in the form of a sprout. Since creation is dependent upon this force power for creation should be invoked on it. The योगिन् should picture in his mind that nectar flows out of कुण्डलिनी . He should also realise that the soul within the body possesses form while pure soul is formless. He should address this soul as ' हंस हंस '. हंस means शिव . शिव exists and functions inside and outside the body just as oil is in the gingelly seed and fragrance in flower. Soul possessing form is of five kinds. Accordingly ब्रह्मा 's seat is the heart, विष्णु 's the neck, रुद्र 's, the centre of the throat; महेश्वर 's the forehead; and शिव 's, the tip of the प्राण . Soul without form is just contrary to the above. Its place is where the प्राण ends. By प्राणायाम the formless soul may be experienced. (Agni Purāṇa, Chapter 214)