Cranial Rhythmic Impulse

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Another rhythm oriented to within craniosacral therapy is called the cranial rhythmic impulse (CRI). This term was later shortened by some practitioners to the cranial rhythm. It commonly manifests at rates of 8–14 cycles a minute. The CRI is the most common rhythm discussed in many cranial courses. The CRI is a conditional rhythm that expresses historical forms and central nervous system and autonomic nervous system activation. It is not a tide, but is an artifact of the presence of unresolved conditional forces and patterns within the system.

Whereas the Long Tide is totally stable, and the mid-tide is relatively stable, the CRI is highly variable in its expression. The CRI is first and foremost an expression of the conditions of our lives as these conditions must be met and centered in some way. It is a superficial rhythm generated as tidal potencies act to center the unresolved inertial forces of trauma, toxins, pathogens and experience in general. It is generated as potency acts to neutralize, contain and compensate for the unresolved forces of experience. The CRI is a level of perception within which effects and affects, such as tissue resistance, fluid congestion, emotional charge, and psychological form, are more easily perceived than the underlying tidal forces that order them.

One way to think of this is to use the analogy of ocean tides. The Long Tide is like the gravitational field phenomena that generate the ocean tides. In turn, the tide generated within the waters of the ocean is like the mid-tide and is relatively stable, while the CRI is like the variable wave forms on the ocean’s surface generated as the tide meets the resistance of the land and the motion of the conditioned winds above. The CRI is thus like the waveform riding on deeper tidal motions and is not a tidal phenomenon.

Any unresolved force held within the system, such as unresolved trauma or toxins, will affect the expression of the CRI in some way. As the system experiences inertial forces of various kinds, and as it holds the effects of these as autonomic nervous system affect, tissue resistance and fluid congestion, the CRI changes in rhythm, tone, and tempo. It is a composite rhythm, which manifests in relationship to all of these factors.

Whereas tissue motility within the mid-tide is sensed to be a unified and holistic dynamic, in the CRI tissue structures may seem to be separate in their expression of motion. Because of this, the CRI has become associated with what is known as craniosacral motion, the individual and particular motions of tissue structures sensed within its faster rate. It is like looking at things from the outside-in with a narrow field of viewing. These externalized motions are commonly termed flexion/external rotation and extension/internal rotation. At the level of the CRI, inertia within the system may be perceived as tissue resistances within and between the separate structures.