True functional system of the body, the cranio-sacral link, formed through the external membrane of the meninges called the dura mater, creates a relationship between the sacrum and the cranium.  The evaluation and mobilisation of the different structures that constitute this cranio-sacral system (face and cranial bones, vertebrae, pelvis, dura mater) contributes to a balanced nervous system and reduces membrane tensions of the dura mater which can cause fatigue, head aches, vertigo, anxiety, etc.