Phase 4 – Mobility of the cranial bone.
“The bones of the skull are moving?” YES! There are 26 bones in the head and they are all in slight rhythmic motion along with the CNS, CSF, membranes, and sacrum. These bones all fit together like the gears of a watch and influence each other. There is” palpable” motion at each cranial suture…meaning that the motion can be detected with your hands. Like the fingers of a baseball glove, the bones are held together with stitch like fibers. That’s why they call them sutures!
So why do these bones eventually form sutures rather than fuse into one large, continuous structure? It is due to the fact that the sutures are formed to accommodate motion that is already present due to the motion of the CNS and dura.
To fit this all together so far, as the brain and spinal cord/CNS fluctuates, this causes movement of the cerebrospinal fluid, which puts pressure on the dura, which therefore moves the cranial bones in a rhythmic pattern palpable by the hands.
Here is a great animated video demonstrating the attachments of the dura (falx and tentorium sections) to the cranial bones, and how they move during PRM.
One last phase to go
Craniosacral Therapist, Osteopathy Student.