There are often many questions about Yin Yoga and specific spinal conditions. Feel free to ask your question here, or check out other posts or contribute input from your own experience.
According to Paul Grilley the purpose of Yin Yoga is to stress 14 Skeleton groups and 10 Myofascial groups.
I was wondering why the erector spinae isn't one of the targeted Myofascial groups. I think that in all forward bends like Caterpillar we do stress the erector spinae?
Paul Grilley includes the erector spinae in what he categorizes as the 10th myofascial group. "Thoracolumbar Muscles: Folding forward stretches them, standing up or lifting something up contracts and strengthens them."