Sarvangasana the name sarvang means all the parts of the body means it is beneficial for entire body. It is an inversion asana. In Sarvangasana your body has reverse blood circulation which is really good for people having knee pain as blood flows back up it opens and prevents any blockage from legs. Body position is upside down in Sarvangasana so all the weight of the body should come on shoulders and back of the neck. With this our shoulders and neck strengthen and get energized. We can maintain this posture for 15-90 seconds and can be repeated for 2-3 times. Kids can also practice this asana as it is very good for them to increase concentration.
After Sarvangasana one should follow Mathsyasana or Fish pose as it is the counter pose nad helps to extend the throat as it is contracted in sarvangasana. Helps people with their thyroid.