Let’s dive into the muscles and bones names and movements )
Here are awesome pictures showing, explaining and pointing exact movements of the bones and muscles in the pose (pictures were taken from www.bandhayoga.com and www.dailybandha.com – I highly recommend to follow those websites. They are full of very useful and interesting information on yoga anatomy).
pic. 1 Movements of bones and muscles in the prasarita padottanasana.