One of the components of the cranial concept for Practitioners practicing Cranial Osteopathy is that the bones of the skull move around the sutures. The movement can be described as an expansion and compression that occurs quite similarly to how the rib cage moves during breathing. This concept has been highly controversial since it was first introduced to the world more than 60 years ago. To date, there is a lot of skepticism about it and the theory is believed to have some basis in 'pseudoscience'. Many believe there is not enough evidence or research to support it. This is all incorrect. There is rather a lot but not enough evidence in this regard. Much of this research can be found on the Cranial Academy website.
Surely there are 5 good reasons to support the concept that the bones of the skull move.
- Embryological: Why are there sutures in the skull? If you look at a skull, there are sutures that make each of its bones distinguishable. They may seem insignificant on the surface but during development, there are many bones that initially separate, then fuse to form a single bone. Even in the body, for example the pelvic bone develops from three separate parts: ischium, ilium and pubis. These three bones fuse without sutures between them. There are many examples like this throughout development and this phenomenon also occurs at the skull level. The occiput, for example, is formed by the fusion of 4 separate components. This fusion is complete and no suture remains between the components. However, there are sutures between the occiput and the bones that articulate with it. The human body would undoubtedly be capable of fusion welding if it wanted to do so. This merger, however, did not materialize. Additionally, skulls can be disarticulated using expansion properties to separate bones and sutures. So since the body can complete fusion why doesn't it?
- Adaptation: Although there are movements in the skull, these movements are not enormous. The proper movement allows the skull to be flexible to better absorb traumatic shocks or variations in intracranial pressure. Part of the skull's function is to contain and protect the brain. If you receive a direct trauma to the skull, the flexibility allowed by the movement of its bones allows them to absorb a good part of the impact, thus allowing the brain to be subjected to minor trauma. If the skull were cast then it would be very rigid, like the outer shell of a helmet. Direct trauma would break it more easily, and the forces of the impact would be transferred to the brain in a much more traumatic way. By not fusing, the skull can better adapt to changes in intracranial pressure. If we think about when a change in this pressure occurs (like when you take a plane or have a cold), then you can understand how it can help if the skull is flexible and its bones can expand to vary the pressure while minimizing the effects on the brain.
- Orthodontic appliances: Let's start from the evidence that the bones of the skull can move. If these were fused and immobile, there would be no reason to even apply orthodontic appliances. Their concept is based precisely on the theory that the head is flexible and can be 'reshaped' to allow the alignment of the teeth.
- Mobility: Much of the controversy over whether or not the bones of the skull are mobile arises from the fact that Osteopaths place their hands on a skull and palpate the subtle movement that occurs underneath. Other figures cannot palpate this movement and therefore theorize that it does not exist. When this subtle movement is perceived, restrictions between the sutures can be appreciated by grasping the accessible bones and mobilizing them within their range of mobility. Then one side is compared with the other. Usually one side moves better than the other. Under normal circumstances each bone has a small range of mobility. By understanding where there are restrictions in the sutures you can work on freeing them until the two sides are symmetrical in their movement. This is what is done every day in the studio on the skull.
- Representation of the sutures: The last evidence can be found in the sutures themselves. This involves a return to anatomy. If you study how movement occurs in the skull in relation to the anatomy of the sutures, then you will find the truth of this concept. There are different types of sutures that are articulated in different ways depending on the area. For example, the frontal overlies the parietal medially, but if you palpate along the coronal suture, there is a transition point where the parietal overlies the frontal. The sagittal suture, for example, acts like a hinge and the suture is assembled in a way that allows this type of function. These are just a few examples of how the skull articulates. The skull can simply be seen as a 3D puzzle that assembles to perform its functions. Furthermore, the dural membranes in the skull have emergence from the sutures. Evidence for this is that epidural bleeding in the skull does not cross the suture lines because the dura runs outside the suture. The dural membranes inside the skull act as a barrier, preventing the bones of the skull from completely fusing.
But can skull bones fuse? Absolutely yes. The same way the process happens in a joint that has no mobility for a long period of time. However, some pathological cases exist. The human body develops a certain way for specific reasons. Nothing happens by chance.