There are several backbends in Yin Yoga that can take you progressively deeper. You can start with Saddle or Sphinx as low backbends, then use a higher Supported Bridge pose and finally, Proud Swan or Seal pose for the deepest spinal extension. For the thoracic spine, Heart melting Pose or Anahatasana is good. Remember to pay attention; if you feel compression in the spine, you have reach the limit of how much that region of your spine can extend.
