One of the components of the cranial concept for practitioners who practice cranial manipulative therapy is that the bones of the head move along the sutures. The movement can be described as an expansion and compression that take place much how the rib cage moves during respiration. This idea has been highly controversial since it was first presented to the world over 60 years ago. To this day, there’s plenty of criticism that this concept is based on ‘pseudoscience.’ Many state that there is ‘no research’ supporting this idea. This statement is incorrect. There may not be sufficient evidence at this time supporting this idea. However, there is much more research showing that there the bones of the head can move, than there is research showing that the bones of the head do not move.
I'd like to to discuss 5 reasons I have found that support the bones of the head do move.
Reason 1: Embryological
Why are there sutures in the head? If you look at a skull, there are sutures throughout the head making each bone identifiable. This may seem insignificant as evidence but during development, there are many bones that form in separate parts and do actually fuse to form one bone. For example, each pelvic bone develops as three separate parts (ischium, ilium, and pubis) that fuse into one bone with no sutures between them. There are many examples of this during development. This even takes place in the head. The occiput forms by the fusion of 4 separate components. This fusion is complete and does not have any sutures between them. There are sutures between the occiput and the bones it articulates with. Clearly the human body would be capable of completely fusing the bones of the head if it intended it to do so. This fusion, however, does not take place or one would be unable to distinguish each separate bone of the skull once fusion had taken place. In addition, skulls can be disarticulated using the expansive properties of rice to separate the bones at the sutures. So if the body is capable of completely fusing the bones of the head, then why does it not do this?
Reason 2: Adaptation
Although there are not large amounts of movement in the head, there is some. Proper motion allows the head to be pliable to better absorb the shock of a trauma or changes in intracranial pressure. Part of the purpose of the skull is to encase and protect the brain. If one receives a blunt trauma to the head, the pliability allowed by movement of the bones of the head allows the bones to absorb much of the impact. This would allow the brain to be less affected by the trauma. If the skull fused, then the skull would be very hard like the outer casing of a helmet. A blunt trauma would break the skull easier like an egg shell and the force would be transferred to the brain more strongly. By not fusing, the head can then change and adapt better to changes in intracranial pressure. If a scenario occurs where the pressure in the head changes (such as flying or having a cold), then it would be helpful for the bones to be pliable and expand. That way, when the pressure in the head changes, the effect on the brain is minimized. Therefore, in terms of being able to handle traumas and changes in pressure, it would make sense of the head to be able to expand.
Reason 3: Braces
We have evidence that the bones of the head can move all around us. If the bones of the head fuse and could not move, there would be no reason for braces. Braces are based on the idea that the head is pliable and can be reshaped to align teeth.
Reason 4: Motion Testing
Part of the reason that there is so much controversy about whether or not the bones of the head move or not is because most practitioners put their hands on a persons head and palpate the subtle movement taking place under their hands. Others who come along who cannot palpate this motion, then argue that this cannot be felt. Although I can feel this subtle motion, I feel restrictions in the cranial bones by getting a hold of the accessible bones of the head and move them through their range of motion. I compare how one side moves compared to the other. Usually one side moves better than the other. Under normal circumstances each bone has a small range of motion. There is significantly more motion than taking a plastic skull and trying to move it. By understanding where there are restrictions in the sutures, then I can work on freeing them up until both sides feel more symmetrical in their movement. I prove this idea to myself every day that I am at work.
Reason 5: Layout of Sutures
Finally the last piece of evidence I have found is in the sutures themselves. This goes back to anatomy. If one studies the way the motion described in the skull and the anatomy of the sutures, then one could see this idea as being plausible. There are different types of sutures and they articulate differently depending on the area. For example, the frontal bone overlaps the parietal bone medially, but as one moves out further along the coronal suture, there is a transition spot followed by the parietal bone overlapping the frontal bone. The sagittal suture for example, acts more like a hinge and the suture is put together in a way that allows for this type of a function. These are just a few examples although this takes place with the way all the bones articulate with each other. Simply put, the bones of the head act like a 3D puzzle that allows the head to go through its motion. In addition, dural membranes in the head come out externally through the sutures. Evidence for this is that epidural bleeds in the head do not cross suture lines because the dura travels externally at the sutures. The dural membranes inside the head act as a barrier preventing the bones of the head from fusing completely.
We also know now that there are structures inside the skull that we are affecting with cranial manipulative techniques. The tentorium, cranial arterials, CSF, also transmit pain information to our brain. This can be attenuated with cranial technique.
I will post a video of the skull bones moving in real time!