The Five Phenomena of the Primary Respiratory Mechanism When Dr. Sutherland introduced the cranial concept, he drew on his many years of study and clinical practice, to base it on fundamental physiologic principles. He had observed 5 basic phenomena at work in the human body. He called these the five phenomena of the primary respiratory mechanism. Though primary respiration has 2 phases, inhalation and exhalation, this is a separate concept from and not to be confused with secondary respiration . Secondary respiration refers to the process that goes on with movement of the rib cage involving a change in volume of the lungs with oxygen and carbon dioxide exchange.
Primary respiration is a deeper, more basic process to life.
The exhalation phase of primary respiration is just the opposite of this. This is not large, but it is a significant amount of change. Estimates place the change at hundredths of an inch, but it varies according to where it is measured. There are cavities and spaces in and around the CNS, and as the brain and spinal cord change shape with the inherent rhythmic motion, the volume of these aforementioned spaces and hence the amount of fluid that they hold will change. This type of motion is not limited to man, but is a basic and vital property of any living organism with a nervous system.