The cerebrospinal fluid starts its journey through the CNS in the first and second ventricles, also called lateral ventricles, where it is pumped in by a group of specialized cells (choroid plexus).
From the first and second ventricles, cerebrospinal fluid (CSF) moves through the third and fourth ventricles, and from there into the subarachnoid space, which is the space between the arachnoid mater and pia mater, and surrounds the entire brain, as well as the spinal cord. The CSF then rejoins the venous system via the arachnoid granulations and dural sinuses.
Various brain structures grouped together form hollow spaces called ventricles.
The ventricles are relatively large hollow spaces within, and formed by, the brain tissue. For example, the corpus callosum, a broad band of nerve fibers that connects the two hemispheres, forms the roof and front walls of the lateral ventricles, while the thalamus forms the side walls and the hypothalamus the floor of the third ventricle. The limbic system (the “emotional brain”) has a similar shape as the ventricles and is nestled around the ventricles.
Since cerebrospinal fluid (CSF) flows around the brain and through the ventricles (brain cavities), and is contained within the meninges, any distortion of the meninges, or any displacement of brain tissue (tumors, aneurysms, hematomas, infections, hemorrhages, etc) impedes the normal in and outflow of the cerebrospinal fluid, and may result in increased intracranial pressure or hydrocephalus. A shifting and/or fracture of the cranial bones from head trauma may distort the shape of the cranium and thus the space through which the cerebrospinal fluid flows, also possibly resulting in increased intracranial pressure or hydrocephalus.
Symptoms may arise with changes in CSF pressure.
Cerebrospinal fluid buildup (and pressure on the surrounding brain tissue) anywhere in its path, such as around cranial nerves that are exiting the skull through the meninges, may result in symptoms such as headaches, vision changes, nausea, vomiting, respiratory changes, emotional disturbances, impairment of mental functions, and hormonal changes, among others.
This explains in part why people with head trauma often experience such a myriad of symptoms, some of which seem unrelated to the trauma itself. Some of these symptoms may not show up until days, weeks, or months later. CSF trapped within the ventricles by a mid-line shift of the brain tissue due to head trauma, tumor, hemorrhagic stroke, or abscess may cause hydrocephalus, a potentially life-threatening condition.
The Primary Respiratory Rhythm can be felt anywhere in the body.
Dr. William Garner Sutherland noticed that the cerebrospinal fluid moves in and out of the CNS (brain and spinal cord) in a rhythmic fashion. This rhythm is a little bit faster than the rate of breathing and a little bit slower than the heart beat. Further, he discovered that the cranial bones move at this same rhythm as the cerebrospinal fluid.
Through further observation, he realized that all tissues of the body move at this rate. He called this rhythm the Primary Respiratory Rhythm. This rhythm is transmitted from the craniosacral system (brain, spinal cord, and cerebrospinal fluid within the meninges) to the rest of the body via the connective tissue.
Trauma to the head or body changes the primary respiratory rhythm.
When the body is exposed to trauma anywhere along the spine or the head, this rhythm changes. Thus, a person (osteopath or craniosacral therapist, for instance), who has learned to “listen” to the body’s rhythms, can very quickly find the areas of the body where trauma has occurred, in the distant or recent past.
The patient may experience many different symptoms, at the time of the trauma or even days, months, or years later, but may not be able to pinpoint the source of the distress. This can be explained by looking at the cranial nerve structures potentially affected by the trauma.
Craniosacral therapy helps the primary respiratory rhythm to return to normal.
Craniosacral therapy helps to release the restrictions in the membrane system and thus facilitates a balanced in- and outflow of the cerebrospinal fluid, i.e. it helps to reestablish a healthy primary respiratory rhythm. This reduces undue CSF pressure on all brain structures, including the twelve cranial nerves and the patient once again experiences health and well-being.
In the next post, we examine the 12 cranial nerves and their functions.