Having created a nice opening of the chest in Part 3, Part 4 goes back to inverted asanas.

The first asana I propose is Sayanasana, which can however be substituted by Pincha Mayurasana. Both asanas are a good link between back extensions and upside-down positions as they combine the chest opening with the inverted position. Sayanasana in particular creates a tremendous space at the base of the throat where the thyroid gland is located.

The supported chin in fact allows that specific spot to open up without tension. Pincha Mayurasana has a similar effect even though the chin has not a direct support. As explained, there is an interaction between the neuroendocrine pathway and the immune system via the hypothalamic-pituitary-adrenal (HPA) axis and this is why I address that area too.

Besides, the Sirsasana cycle which follows exerts a direct stimulation on the central nervous system (CNS), brain and spinal cord, which is also involved in the neuronal pathway that regulate the immune system. Exhalation in Sirsasana will allow to maintain a parasympathetic dominance. Eyes, tongue, temples, the whole facial skin and all sensory organs should remain as passive as possible.