There are three granthis (psychic knots) in the physical body which are obstacles on the path of the awakened kundalini. The granthis are called brahma, vishnu and rudra, and they represent levels of awareness where the power of maya, ignorance and attachment to material things is especially strong. Each aspirant must transcend these barriers to make a clear passageway for the ascending kundalini.
Brahma granthi functions in the region of mooladhara chakra. It implies attachment to physical pleasures, material objects and excessive selfishness. It also implies the ensnaring power of tamas - negativity, lethargy and ignorance.
Vishnu granthi operates in the region of anahata chakra. It is associated with the bondage of emotional attachment and attachment to people and inner psychic visions. It is connected with rajas - the tendency towards passion, ambition and assertiveness.
Rudra granthi functions in the region of ajna chakra. It is associated with attachment to siddhis, psychic phenomena and the concept of ourselves as individuals. One must surrender the sense of individual ego and transcend duality to make further spiritual progress.
