Head and Shoulders Above The Rest
Compiled from the writings of Srivatsa Ramaswami
If the position of the sun (stomach) is above and the moon (the head) below, it is called an Inversion (viparita karani). You have turned your body upside down. Headstand and Shoulder Stand are also considered mudras, the viparita karani mudras.
Headstand (Sirasasana), and its better half, Shoulder Stand (Sarvangasana), are called the King and Queen of yoga poses. These two head-fixed inver