In this post I'm discussing the tentorium cerebelli an important membrane that protects our brain and how craniosacral therapy can free up the dura, nerves and connective tissue so that the brain and nervous system can function better. I'll discuss how releasing tension held in the tentorium can benefit the rest of the body. I've noticed this membrane is particularly tight in people who tend to be control freaks! I don't mean that in a bad way, we all like a bit of control, but I'm talking about being so control it's difficult to let go and relax.
The tentorium carries information about how we move our neck and heads and transmits it to our central nervous system through the cervical tract. When people are stressed but particularly, when they are trying to control their environment, their emotions, the people around them, they hold a lot of tension in the tentorium. It's stretched like a rubber band. This impairs rest, digest, sleep etc. It's relatively easy to feel when this membrane is tight and to allow it to release itself, offering significant relief and expansion. I'll talk more about that later. First up, some anatomy!
What is the tentorium?
The tentorium is a double layered membrane at the back of the cranium roughly in line with the top of the ears. The brain stem passes through the tentorium which separates the cerebrum of the brain above from the cerebellum below and covers the top of the cerebellum like a tent.
It is attached to the occipital bone which is the large, flat bone at the base of our skull and also to the petrous portion of our temporal bones. It's also attached to the occiput, parietal, and clinoid processes of the sphenoid as well as the falx cerebri. This matters because it's attached to some major large cranial bones. If a membrane is attached to bones and the membrane is impacted or under persistent tension, this will affect the mobility of the bones, and vice versa.
The tentorium has a close relationship to the sinuses, especially the straight sinus and sigmoid sinus which you can see below
Blood flows to the tentorium from the external carotid, internal carotid, posterior cerebral, and also the vertebral arteries so it's well supplied. The tentorium has close relationships with various cranial nerves, 3,4,5.
What does the tentorium do?
It protects the brain and responds to pressure in the cranium, helping to disperse it so fluids can flow appropriately around the brain. It's a key communicator of mechanical , neurological and emotional information which is transmitted through the cervical tract. Fluid flow and pressure are related, as pressure in the cranium increases the body tries to reduce production of cerebrospinal fluid. Tension held in the cranium therefore has a direct impact on production of CSF, which in turn affects our entire nervous system functioning.
Releasing the tentorium can help: - improve neck mobility
- reduce cranial pressure/tension
- eliminate vascular headaches
- improve sinus function
- support lymphatic flow
There is a plexus, a group of nerves kind of like a control centre that is hosted within the membrane which carries rich information and allows the tentorium to be constantly adapting to incoming stimuli including pressure and movement.
When people are stressed they change the way they move and also the way they breathe. Their posture changes. Sometimes the neck compresses and the shoulders round or one feels higher than the other. The tentorium has a close relationship with the neck because sympathetic innervation comes from nerve fibres from the superior cervical ganglion in the neck. All of this affects the flow of fluid in the nervous system.
So what affects how we move our head and neck? Well, what we perceive is around us, what we feel is in front of us, how we move in space, how we adapt to our environment, the condition of our body etc.
The tentorium quality relates inherently to what we see and hear. The tentorial nerve also called the Nerve of Arnold is a branch of the opthalmic nerve that supplies the tentorium. So if we are for example staring at a screen for many hours a day, or straining our vision in some way, or perhaps trying not to see something, there is a neurological response in the tentorial and tentorium. If we are constantly exposed to violent sounds or loud noise this can also impact the quality of the tentorium.
What does the Tentorium feel like?
You can try to feel this yourself at the back of your skull above the occipital basel. In people who have persistent stress or headaches or even tension in the neck, once they start to receive craniosacral treatment, engaging with the tentorium can often feel as a therapist, like meeting a thick rubber band that has been stretched, rather than a fluidic and adaptable soft tissue. You can sense the load that the membrane has had to bear, and how it has become thick and solid in order to offer its supporting role. However, this has a knock on effect on cranial pressure, mobility particularly in the temporal area and also on the cervical spine.
How does a therapist work with the Tentorium?
Engaging with the tentorium with gentle touch and subtle pressure whilst being aware of how reciprocal tension changes in the temporals and the sternocleidomastoid as well as elsewhere in the thoracic region in particular, can facilitate a relatively swift softening of the membrane, increasing tone and allowing the cranium to start to expand and become more spacious. It actually feels like the tentorium is expanding and stretching out sideways or laterally towards the back of the ears. I often invite my clients to notice this sensation, and usually it's very obvious to them, as is the immediate sense of ahhh, relief and relaxation.
Releasing or allowing the expansion and flexibility to return to the tentorium can facilitate an expansion of the cranium. When this happens the brain, dural membranes,and cranium expand & widen. The spine and dural tube lengthen. This helps the flow of fluid and drainage of CSF which supports the glymphatic system carry fluids away from the brain. People often experience this in their bodies as a feeling of inflating, becoming heavier, expanding into their space, or as a silencing or peace.
Restoring the tentorium to its supple and supporting role, also offers freedom and flexibility the cranial bones and the other membranes, particularly the falx cerebri, which consequently has a beneficial effect on the sinus system.
So the connection between the way we move our head and neck, our nervous system and the efficiency of our lymphatic system is well established in the craniosacral model. You'll also find this in yoga and other holistic body work practices where there is a big focus on the neck mobility.
Everything we feel results in a physical response in the body, and the response is held in our membrane system. It is fortunately, particularly keen to help us out and so through cranial work, it is possible to release persistent shock and tension, or old chronic injuries relatively easily.
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