The controversy about whether the bones of the skull move relative to each other has absorbed more hours of discussion in the lives of Cranial Therapists than perhaps any other subject. From the perspective of Allopaths (standard American medical doctors) the bones of the skull fuse fully by the age of 25. What this means is that any therapy based on manipulating the bones of the skull would be ineffective. This is somehow extended to the idea that manipulating the skull at any age lacks therapeutic benefit, which is the view of many Allopaths. This post is my attempt to organize and clarify my routine rebuttals to a blanket statement of inefficacy of cranial manipulation due to the absence of cranial bone movement.
Greys Anatomy declares fusion of the cranial bones by the age of twenty five. However Upledger () states that both European and Israeli anatomy texts do not describe this fusion. Upledger states that this discrepancy may be related to the freshness of the cadavers used in the dissections, however it may be more likely related to the 120 year long battle between Allopaths, who think in terms of pharmaceutical and surgical remedies, and Osteopaths, who may prescribe manual techniques for the same symptoms.
There are 8 bones that comprise the cranium which encompasses the brain, and 12 bones which comprise the face. The bones are all individually named. Although the articulations of these bones may become restricted with age, it is still a simple matter to disassemble a mature skull into it’s individual bones by filling it with grain and soaking it in water overnight. The next day the expanded grains will have deconstructed the skull into the individual bones. The bones always break apart along the suture lines between the bones. If the bones had fused together it is unlikely that disassembly would always be so clean.
There is strong evidence that there is living cellular tissue between the cranial bones, as both vascular and nerve supply has been observed there. (Upledger CST 1 training) This cellular tissue is a form of connective tissue, which behaves according to the unique characteristics of this tissue type-stiffening under abrupt load, and becomming increasingly plyable under constant low amplitude loading. This characteristic enables the tissue to resist sudden changes, but adapt over time if there is no negative feedback on the movement. Stretching is a great example, in that when starting a stretch a muscle may feel firmly short, but after applying constant pressure it lengthens. It is the connective tissue, or Fasciae, that is lengthening, rather than the muscle fibers.
Many nerves pass through the skull between the bones of the cranium. Any misalignment of these bones may interfere with the function of these nerves. Cranial manipulations can often very quickly alter symptoms related to cranial nerve compression. If the bones of the skull were fussed together, this outcome would not be possible.
The organization of the joints between the cranial bones, which are called sutures, displays many features related to the function of the cranial bones as they move against each other. The suture running lengthwise along the top of the skull, the Sagital Parietal suture, is shaped like a hinge, allowing the two major cranial bones to accomodate movement on their side of the body. It is hard to imagine any other function for a complex, localized joint configuration such as this. The Parietal / Temporal suture is shaped like a slide. I believe that this relates to dissipating shock loads that travel up the body when running. The high frequency, high amplitude energy passing up through the body from heel strike needs an exit point, and this suture is both perfectly configured and positioned for dissipating shock loads. The shock absorption function requires that the Parietal and Temporal bones pass over each other. It is interesting to note that four legged animals which don’t have the tensional and compressional dynamics of tailless bipeds, don’t have this type of suture between the Temporal and Parietal bones. I additionally believe that this suture is an integral part of our lateral stability mechanism, and work on it needs to be integrated into any therapy directed to lateral stability.
I certainly am not saying that cranial bones always move relative to each other, only that they should move in certain ways under certain circumstances. It is rare for me to find a skull without at least some inhibition of movement, and I often am called to work on skulls that are extremely jammed, to the extent that getting their bones moving is akin to untying a knot. Fixation of cranial bones can occur from any type of head trauma, and is often linked to difficult births. The health issues associated with cranial bone fixations span the breadth of the physical, emotional and cognitive challenges we face, and when tackling any issue it is worthwhile to identify how large a contribution cranial bone fixation is making to the imbalance.