Some science behind the scenes

Craniosacral system

Craniosacral Therapy – Dr John Upledger

The craniosacral system is a recently recognized physiological system. It possesses its own physiological rhythmic activity. It has all the characteristics of a semi-closed hydraulic system.  Functionally, it is intimately related to the central nervous system, the autonomic nervous system, the neuro-musculoskeletal system, and the endocrine system. Its boundaries are formed by the meningeal membranes, most specifically the dura  mater [see spinal cord].

The system's fluid intake is via the choroid plexus, which allows passage of fluid from the vascular system into the ventricular system of the brain.

The choroid plexus is selective in its passage of solutes from blood into the craniosacral system. The fluid which passes through the choroid plexus is known as cerebrospinal fluid. Cerebrospinal fluid is returned into the venous system by the arachnoid villae.  These villae are most  concentrated in the sagittal venous sinus within the cranial vault, but are found in significant numbers throughout the intracranial venous drainage system.

A semi-closed hydraulic system is formed by the dura mater membrane and its contents.  The dural membrane is essentially impermeable to the cerebrospinal fluid which it holds.  Intake and outflow of fluid from the system is by means of specialized tissue structures (choroid plexuses and arachnoid villae) which are under homeostatic control.  These intake and outflow mechanisms qualify the hydraulic system as semi-closed……….

The craniosacral semi-closed system obeys the laws of fluid mechanics.  The cerebrospinal fluid which fills the system is largely incompressible and therefore behaves like water.  It is our belief that although cerebrospinal fluid is moving within the system, the movement is of low velocity and without much force.  Therefore we suggest at this time that the cerebrospinal fluid obeys the laws of fluid mechanics as though it were static.

The craniosacral system and flexing

The craniosacral system is not still.  The fluid in the system ‘pulses’ at about 6 to 12 cycles per minute – so low frequency – and as a consequence also tends to alter the body as well.  In effect the body flexes in tune with the rhythmic pulses of the cerebrospinal fluid in the dura mater.

The fact it flexes has been proved.  Measurements have been taken and the admittedly tiny movements and flexing of the body is detectable physically.  You have to be a good osteopath to detect it, gentle and receptive to tiny movements, as the detection is achieved via palpation. 

Green C, Martin CW, Bassett K, Kazanjian A (1999). "A systematic review of craniosacral therapy: biological plausibility, assessment reliability and clinical effectiveness". Complement Ther Med 7 (4): 201–7.

……….in accord with a basic tenet of craniosacral therapy, there is evidence for a craniosacral rhythm, impulse or 'primary respiration' independent of other measurable body rhythms (heart rate, or respiration)...

However, these and other studies do not provide any valid evidence that such a craniosacral 'rhythm' or 'pulse' can be reliably perceived by an examiner

One of the reasons for rejection by the western medical  fraternity is that there is still a belief that the skull is fused and cannot flex.  This belief, however, is not one which is held in the east – Italian doctors, for example, have long known that the skull is not ‘fused’ and the sutures allow small movement.

The whole body rotates and widens in a period known as ‘flexion’ and then there is a neutral or ‘idling’ zone after which the body rotates internally in a process known as ‘extension’.  These movements are used to diagnose illness and also provide treatment.  The strength of the motion, the symmetry of the body during these motions and identification of what are called ‘resistance barriers’ – points where the normal motion and movement seems to be encountering some sort of physical resistance -  are all used  to find illness, disease and other physical damage.

This ‘whole body’ response to the pulsing is based on the concept of ‘fascial continuity’.  In effect, and put simply, everything in the body is connected, it is one inter-related physical system connected up by tissue that doesn’t have an ‘end’ or a ‘beginning’ but is continuous throughout the body.  So any pulsing motion is going to affect the whole body not just the dura mater.

One of the questions that often gets asked is why does it pulsate?  And this has not been answered.  Some suggest that it is due to the earth’s pulsing magnetic field, for example, which at 8HZ is somewhat similar to the frequency of the craniosacral rhythm, we are pulsing in tune with the earth!  But the answer is, I’m afraid that we don’t know.