The Sanskrit word yoni means ‘womb’ or ‘source’. In this context it means that this asana is the female equivalent of siddhasana. It is to be practised by women instead of siddhasana.
Sit on the floor with your legs extended straight in front of you. Fold your right leg and place the sole of the right foot so that it is in contact with the inside of the left thigh. Adjust your right heel so that it presses firmly against the front of your vagina (labia majora).
Adjust your body position so that you are comfortable, while simultaneously feeling the pressure of the right heel. Then fold your left leg and place the left foot on top of the right calf. Gently slide the left toes into the space between the right calf and thigh. Pull your right toes upwards into the space between your left calf and thigh. Adjust your body so that you feel comfortable. Ensure that your knees are firmly on the ground. Make sure that your spine and head are held erect. Close your eyes and imagine that your body is firmly fixed in the ground as though it is a tree.
One should refer to the sections in siddhasana for more information on the position of the hands and arms, general advice and limitations.
Siddha yoni asana is an excellent pose and the equal of padmasana. It is utilized with many other practices which aim at awakening mooladhara chakra.
This asana is necessary for women because the position of the mooladhara chakra is slightly different to that of men.
It has a direct influence on the nerve plexuses of the female reproductive system. It helps one to gain control over the neuropsychic impulses which are concerned with the mooladhara chakra and the associated physical sexual organs.