Mastery of Asana and Pranayama is impossible without the knowledge and mastery of Bandha (lock, bond) and Mudra (seal). The various Bandhas or internal locks are the basic instruments for the retention and channeling of psychosomatic energy (Prana). These should be practised by every serious Sadhaka (seeker, accomplisher) with great intensity and care, until these contractions of certain muscles can be hold spontaneously for extended periods.
Generally three such locks are distinguished:
1. Mula-Bandha, (root-lock, contraction of the rectum)
2. Uddiyana-Bandha (upward-lock, contraction of the peritoneum)
3. Jalandhara-Bandha (waterpipe-lock, contraction of the throat)
The performance of all three locks together is called Maha-Bandha (great lock) by the adepts of Hatha-Yoga. The Mudras or yogic seals are a number of sophisticated practices consisting of Asana (posture), Bandha (lock) and Kumbhaka (retention of breath). According to the Yoga-Shastra they give both Bhoga (enjoyment) and Mukti (liberation). They are the stairways leading to the realms of higher Yoga and expanded consciousness. Some of the basic Mudras are Ashvini-Mudra (horse seal), Kaki-Mudra (crow seal), Manduki-Mudra (frog seal), Shanmukhi-Mudra (six-face seal ), Yoni-Mudra (vulva seal), Matangi-Mudra (elephant seal), Pashini-Mudra (noose seal) and Maha-Mudra (great seal). Most eminent are Viparita-Karani-Mudra (inverse-action seal), Khecari-Mudra (space-walking seal) and Vajroli-Mudra (thunderbolt or diamond seal). Viparita-Karani is often associated with Urdhva-Sarvangasana (shoulder-stand posture); true adepts however prefer Shirshasana (head-stand posture). Khecari-Mudra consists of cutting the tongue`s frenum and elongating it until it can be turned back and inserted into the nasal cavity. Vajroli-Mudra consists of three sexo-yogic practices called Vajroli, Sahajoli and Amaroli, which give full control over sexuality and corresponding secretions. It is dangerous to perform these ambitious practices without the proper guidance of an experienced teacher or Guru.