Dragon pose is a yin yoga pose that is a deep hip and groin opener. It can help in sciatica and helps to open the hip flexors and quads. You can place padding under the back knee or under the back shin. Options include tucking the toes under and lift the back leg or pressing the back toes down.
Variations help to stretch the ankle and achilles tendon by pushing forward with the front knee, or raising the hands up on the front thigh or lowering them down to the forearms. You can also deepen the external roation of the hip by bringing the front foot out.