This article was written by Srivatsa Ramaswami and is reproduced here with his kind permission:
One of the less known, but significant, teachings of Sri Krishnamacharya was about the maintenance of the health of vital organs of the body, the six kosas. He makes a pointed reference to it in his Yoga Rahasya. Kosa in Sanskrit means a sac or a bag. In the olden days the king’s treasury used to be called the kosa because gold used to be kept in pockets, leather pouches. The human body has six important organs kept in such bags and hence are called kosas.
One is hridaya kosa, the heart kosa, contained as I had explained in some earlier articles in a sac called the pericardium and acts as the driving force in a subsystem called the circulatory system, or rakta sanchara. Likewise is the other vital organ, the lungs known as svasa kosa or breathing bag which is the driving force behind the respiratory system. It is called a kosa because it is contained in a bag-like strong membrane called the pleura. Below the diaphragm is another important bag, the stomach, also known as anna kosa or food bag. It is the driving force behind the digestive system. In the pelvic region there are three more kosas or sacs. One is mala kosa or faeces bag. Then we have mutra kosa or the urine bag or the bladder and finally garbha kosa or the fetus bag or the uterus, the central organ in the reproductive system. In men it is the prostate.
My Guru used to mention that the positional integrity of these kosas must be maintained for the optimal functioning of these kosas and the subsystem they serve. Yogis of yesteryears had defined the positions or sthanas of these organs. They had also discovered unique procedures, yogic procedures, to maintain the position and tone of these kosas. Apart from several asanas and vinyasas, they came out with some extraordinary procedures like mudras, bandhas vipritakaranis like sirsasana and sarvangasana., kriyas and of course pranayama. Several of these procedures, like pranayama, look insipid, and procedures like Kapalabhati, Nauli look grotesque to non-yogis. Yogis who stay in headstand and shoulder stand for long durations appear to some non-yogis as just weird. Many modern yoga practioners who practice these do it as a matter of routine but these are great inventions of yogis to give complete health to all the six kosas containing very vital organs
By giving considerable importance to these less understood but very powerful procedures, Sri Krishnamacharya gave a more complete picture of Yoga and thus taught a well rounded yoga system . The human body is said to be a shat-kausika-sarira or a body made of six kosas or sacs. Yoga takes care of these six important kosas, thereby nurturing important organs. Every aspect of yoga is quite significant.