Chakravakasana: Releasing Tension from the Neck, Shoulders, Upper Back, Mid Back, Lower Back, HIps and Knees
These movements are often called Cat/Cow. I like the name Desikachar uses for the movement a little better. Chakravakasana refers to a mythical bird that is puffing up its chest. I think this gets at the essence of the back bend better than the image of a rickety cow whose back is swayed so that its belly is falling towards the floor. Instead, if you think of the expansion of the chest and keep the neck and lower back long, using the core strength to stabilize those areas, ultimately you are going to be better off.
When done in a way that is useful to the practitioner, this pose can release tension from the neck, shoulders, upper back, mid back, lower back, hips and knees. Not too shabby for a movement that is so easy and simple.