Which literally translates to mean...
Janu = Knee, Sirsa = Head and Asana = Steady Pose.
This posture will release tension in the hamstrings, buttocks and hips.
How to Perform Janu Sirsasana
Sit on the floor with your legs straight in front of you (dandasana). Use a blanket under your buttocks if necessary. Bend your right knee, and position the sole of the right foot against the left inner thigh as close to your body as you comfortably can and relax the right knee towards the ground.
Extend the left leg away, flex your left foot so that your toes are pointing straight up and relax the back of the leg towards the ground.
Rotate your torso to the left a little, so that your navel lines up with the middle of the left thigh. This might provide enough of a release if so stay here and breathe slowly.
When you are ready, on an inhalation lengthen your spine and as you exhale start to walk your hands towards your feet.
Take your time to lengthen and release into a comfortable stretch. If possible the lower belly should touch the thighs first, then work to release deeper taking the head towards the legs last.
Listen to your body and only go as far as you feel comfortable. If it feels comfortable reach forward and hold the left foot with both hands.
Stay in the pose anywhere from 1 to 3 minutes and then repeat on the other side.
Never force the body into the posture work with the breath to slowly and gently release the body into the pose.