In any asana/pose we learn to ground, to feel our connection to the earth and to the universe. On a physical level, we are able to use the rebound energy from rooting down to reach up, to extend, and more specifically, to extend the spine. Extension of the spine against gravity is the work of each asana, and it is also the fruit of the labor. We are creating space to allow freedom of movement in the spine and to allow freedom for the nerves to give feedback to the brain. The body functions better in general when there is extension of the spine.
A seasoned student recognizes the next step is to create both length and breadth in the body, especially in the ribcage, and especially using breath as a tool. Freedom of movement helps us to feel more open, capable, stronger, resilient, and thus we begin to become more accepting, flexible, patient, and forgiving. Creating space in the body allows us to get past where we are stuck in our chakras, the energy centers of the body. Creating space invites healing both physically and emotionally and opens the way for us to then focus on our spiritual journey. Enjoy your practice. Namaste!